Objective: To evaluate the changes of heart structure and function in elite Chinese weightlifters by spot tracking technique. Methods: Chinese elite male weightlifters (weightlifter group, n=16) and age-matched healthy men (control group, n=16) were included as subjects. Transthoracic echocardiography and speckle-tracking automatic functional imaging were used for two-dimensional myocardial strain measurements. Results: The thickness of septum and left ventricular (LV) posterior wall and the myocardial mass index of LV were all higher than those of the control group [(9.3±1.3) mm vs. (8.0±0.4) mm, (9.2±0.8) mm vs. (8.0±0.8) mm, (77.8±12.8) g/m² vs. (67.8±11.2) g/m², all P<0.05]. Although the LV ejection fraction (LVEF) and global long axis strain value (LVGLS) were not significantly different from those in the control group, the LV mean Sm and Em reflecting the systolic and diastolic functions of the LV were lower than those in the control group (P<0.05). Further myocardial strain analysis showed that the absolute value of the long axial strain of the basal anteroseptal and mid-inferoseptal segments of the weightlifters were significantly lower than those of the control group [ \left|(-15.1\pm 4.2)\mathrm{\%}\right| vs. \left|(-18.7\pm 3.0)\mathrm{\%}\right|, \left|(-18.8\pm 2.6)\mathrm{\%}\right| vs. \left|(-21.3\pm 2.8)\mathrm{\%}\right|, all P<0.05]. There was no significant difference in other segments. The athletes were divided into two groups according to their best performance in the National Youth Games. The athletes were divided into two sub-groups according to their performance in the National Youth Games. The thickness of the septum in the sub-group with better performance (who ranked the 1^st to 8^th) was larger [(10.2±1.1) mm vs. (8.5±1.0) mm, P<0.05], and the absolute value of the long-axis strain in the mid-inferoseptal segment was lower [ \left|(-17.1\pm 2.1)\mathrm{\%}\right| vs. \left|(-20.4\pm 2.1)\mathrm{\%}\right|, P<0.05]. Conclusion: The thickening of septum is more obvious in the excellent weightlifters, accompanied by the decrease of myocardial systolic function. The speckle-tracking technique of echocardiography can identify the changes of the heart structure and function of elite athletes at an early stage, which may provide a basis for sports medicine supervision and the selection of excellent talents.

Objective: To compare and analyze the difference between the injuries of recreational skiers in public ski resorts and those of skiing athletes in official competitions, and to explore the suggestions of medical insurance for these two types of skiers. Methods: The injury data of recreational skiers in Chongli District, Zhangjiakou City, Hebei Province during 2018-2019 and 2019-2020 snow seasons, and the injury data of skiers in two official international skiing competitions during 2019-2020 snow season and domestic test events in Chongli District of 2021 Winter Olympic Games were analyzed retrospectively, and the similarities and differences were compared. Results: A total of 1 187 injuries occurred to recreational skiers in the two public ski resorts during the 2018-2019 snow season, with an injury rate of 0.3%.There were 1 277 injury sites in total, and the most frequent injury sites were head and neck (230 cases, 18.0%), followed by knee joint (204 cases, 16.0%) and lower extremity (131 cases, 10.3%). Thirty-one skiers were injured in the two official international skiing competitions in the 2019-2020 and 2020-2021 snow season, and in the domestic test competitions in the 2021 Winter Olympic Games, and the injury rates were 11.5%, 17.2% and 12.0%, respectively. There were 37 injury sites in total, among which 11 (29.7%) were in the head and neck, followed by 6 (16.2%) in the knee joint and 5 (13.6%) in the chest, rib and abdomen. Conclusion: In order to better guarantee the safety of skiers and timely provide corresponding medical help, safety facilities and technical guidance should be added to the snow resort for leisure skiing, and medical stations should be set up in the snow resort. As the formal ski racing for skiing athletes during the game has 30 to 80 times higher injury ratesthan recreational skiers, and compared with the recreational skiing, head and neck injury rate is higher, and the damage is much heavier, more complete first aid facilities and experienced medical workers are, needed so the field should be equipped with the circuit inside the quantities, track fixed outside the clinic, surrounding referral hospitals set up trauma centers to provide athletes with more timely medical care.

Objective: To investigate the correlation between the quadriceps cross-sectional area (CSA) and quadriceps muscle volume (QMV) at different horizontal levels from the upper edge of the patella, and to determine the best observation position. Methods: Thigh magnetic resonance imaging (MRI) images of 22 Chinese young men [age: (29±6) years] with anterior cruciate ligament (ACL) rupture were examined. The CSA was measured at 18, 15, and 12 cm above the upper edge of the pate-lla (denoted by CSA-18, CSA-15 and CSA-12 respectively), and the QMV and CSA were determined by semiautomatic segmentation. A curve model was established to estimate QMV. Bland-Altman analysis was performed to determine the confidence limits of the volumes. Results: On the unaffected side, the mean QMV was (1 944.45±323.77) cm³. The quadriceps CSA at the upper edge of the patella at 18, 15, and 12 cm was (80.80±12.16) cm², (77.53±12.03) cm², and (72.68±10.51) cm², respectively. The coefficients of determination (R²), ascertained using curve estimation models, for the 3 positions were 0.819, 0.755, and 0.684 (P<0.001), and the standard deviations of the volume estimated value (SEE) were 7.4%, 8.7%, and 9.8%. The fitting equations of the three horizontal positions were all good, but the fitting degree of CSA-18 was the highest. The Bland-Altman scatter plot showed that the arithmetic means of the QMV at 18, 15 and 12 cm from the upper edge of the patella 0.8 cm³, -1.1 cm³, and 0.9 cm³ and 95% limits of agreement (LoA) were (-268.8, 270.5), (-315.2, 313.1), and (-355.7, 357.5), respectively. The estimated QMV was in good agreement with the measured value. The difference between the estimated CSA-18 and measured values was the smallest. The results on the affected side were consistent. Conclusion: The correlation between QMV and CSA in the young men with the upper edge of patella as baseline was reliable and consistent. Among them, CSA-18 had the highest correlation with the QMV. However, different observation sites could be selected for different injuries of the quadriceps.

Objective: To summarize the experience in the diagnosis and management of septic arthritis after anterior cruciate ligament reconstruction. Methods: A retrospective review was conducted of all the arthroscopic anterior cruciate ligament reconstructions performed at Department of Sports Medicine, Peking University Third Hospital between January 2001 and December 2020. In the study, 65 of 27 867 patients experienced postoperative septic arthritis. The incidence, presentation, laboratory results, treatment, and outcome of all the infected patients were analyzed. The experiences of diagnosis and management of septic arthritis after anterior cruciate ligament reconstruction were summarized. Results: A total of 27 867 anterior cruciate ligament reconstructions were performed at our department between January 2001 and December 2020. In the study, 65 (0.23%) patients were identified with postoperative septic arthritis. The most common symptoms of the infected patients were fever (38.7±0.5) ℃, knee swelling, pain, and restricted motion. The mean peripheral white blood cell count (WBC) was (9.2±2.6)×10⁹/L (range 4.2×10⁹/L-19.4×10⁹/L), with (72.5±6.3) % (range 54.9%-85.1%) polymorphonuclear neutrophils (N). The mean erythrocyte sedimentation rate (ESR) was (59.9±24.1) mm/h (range 9-108 mm/h), C-reactive protein (CRP) was (10.9±5.7) mg/dL (range 1.2-30.8 mg/dL), and fibrinogen (FIB) level was (7.0±1.6) g/L (range 3.7-10.8 g/L). All of the laboratory results were statistically higher in the infection group compared with the normal postoperative group (P<0.001). The synovial white blood cell count (SWBC) of aspirated knee joint fluid was (45.0±29.8)×10⁹/L (range 7.1×10⁹-76.5×10⁹/L). Polymorphonuclear cell percentage (PMNC) was (90.27±7.86) % (range 60%-97%). In the study, 45 patients (69.2%) had positive aspirate cultures. Microbiology showed coagulase-negative Staphylococcus (CNS) and Staphylococcus aureus (SA) were the most common bacterium (34 cases and 7 cases, individually). There were 26 methicillin-resistant Staphylococcus. Both conservative (16 patients) and operative (49 patients) treatments were effective, but conservative group had a longer recovery time (5.6 d vs. 1.6 d, P=0.042). Conclusion: Septic arthritis after arthroscopic anterior cruciate ligament reconstruction is a rare but potentially devastating complication. The correct diagnosis relies on synovial fluid analysis and bacterial culture. Our proposed treatment protocol is arthroscopic debridement and antibiotic therapy as quickly as possible.

Objective: To assess the mid-to-long term clinical outcomes after anterior cruciate ligament (ACL) revision surgery and to analyze their predictors. Methods: The medical records of 235 patients undergoing ACL revision surgery between Jan. 2001 and Dec. 2015 at Department of Sports Medicine, Peking University Third Hospital were reviewed. Data were collected including demographic information, information related to revision surgery (time and cause of graft failure, date of revision surgery, surgical technique, combined injuries and management, etc.), as well as information related to primary ACL reconstruction (time, cause and mechanism of first-time ACL rupture, date of primary ACL reconstruction, surgical technique, combined injuries and management, etc.). Patients were followed up at least 2 years after revision surgery for clinical outcomes [Tegner score, Lysholm score, and International Knee Documentation Committee (IKDC) subjective knee score]. Post-revision surgeries on the involved knee and the contralateral knee joint were also documented. Multivariate regression model was used to analyze the predictors of clinical outcomes after ACL revision surgery. Results: A total of 166 (70.63%) patients were followed up at a mean of (4.44±2.40) years (2.03-14.63 years). Clinical outcomes improved significantly at the last follow-up from pre-operative level, with the Lysholm, Tegner, and IKDC scores improving from 70.51±21.25, 3.39±1.77, 63.78±15.04 to 88.64±14.36, 4.67±1.739, 80.23±13.31 (P<0.05), respectively. Three (1.81%) patients experienced infection while 39 (23.49%) patients underwent surgery after revision surgery during the follow-up. Compared with that those occurred during sports, graft failure that occurred during daily activities or due to surgical technical errors that led to poorer clinical outcomes, with the Lysholm, Tegner, and IKDC scores of 9.90 (95%CI: 1.49-18.31), 1.41 (95%CI: 0.10-2.72), 10.35 (95%CI: 0.17-20.54), and 8.53 (95%CI: 1.31-15.75), 1.28 (95%CI: 0.14-2.43), 9.39 (95%CI: 1.03-17.74) lower, respectively. Compared with antero-medial portal, transtibial technique for placement of the femoral bone tunnel showed poorer Lysholm scores of 11.18 (95%CI: 4.73-17.63, P=0.001). Concurrent repair of medial meniscus yielded higher IKDC scores of 11.06 (95%CI: 1.21-20.92, P=0.029) than those with intact medical meniscus. Other factors showed no significant effect. Conclusion: ACL revision surgery is able to restore knee stability and improve knee function. Graft failure caused by sports, concurrent repair of medical meniscus and antero-medial portal technique predicts better outcomes after revision surgery.

Objective: To explore the stress distribution characteristics of the graft after anterior cruciate ligament (ACL) reconstruction, so as to provide theoretical reference for the surgical plan of ACL reconstruction. Methods: Based on 3D MRI and CT images, finite element models of the uninjured knee joint and knee joint after ACL reconstruction were established in this study. The uninjured knee model included femur, tibia, fibula, medial collateral ligament, lateral collateral ligament, ACL and posterior cruciate ligament. The ACL reconstruction knee model included femur, tibia, fibula, medial collateral ligament, lateral collateral ligament, ACL graft and posterior cruciate ligament. Linear elastic material properties were used for both the uninjured and ACL reconstruction models. The elastic modulus of bone tissue was set as 17 GPa and Poisson’s ratio was 0.36. The material properties of ligament tissue and graft were set as elastic modulus 390 MPa and Poisson’s ratio 0.4. The femur was fixed as the boundary condition, and the tibia anterior tension of 134 N was applied as the loading condition. The stress states of the ACL of the intact joint and the ACL graft after reconstruction were solved and analyzed, including tension, pressure, shear force and von Mises stress. Results: The maximum compressive stress (6.34 MPa), von Mises stress (5.9 MPa) and shear stress (1.83 MPa) of the reconstructed ACL graft were all at the anterior femoral end. It was consistent with the position of maximum compressive stress (8.77 MPa), von Mises stress (8.88 MPa) and shear stress (3.44 MPa) in the ACL of the intact knee joint. The maximum tensile stress of the graft also appeared at the femoral end, but at the posterior side, which was consistent with the position of the maximum tensile stress of ACL of the uninjured knee joint. More-over, the maximum tensile stress of the graft was only 0.88 MPa, which was less than 2.56 MPa of ACL of the uninjured knee joint. Conclusion: The maximum compressive stress, von Mises stress and shear stress of the ACL graft are located in the anterior femoral end, and the maximum tensile stress is located in the posterior femoral end, which is consistent with the position of the maximum tensile stress of the ACL of the uninjured knee joint. The anterior part of ACL and the graft bore higher stresses than the posterior part, which is consistent with the biomechanical characteristics of ACL.

Objective: To measure the electroencephalography (EEG) of the patients with anterior cruciate ligament (ACL) rupture when performing joint position perception movement task, to compare the differences between the ACL rupture side and the unaffected side, to identify the EEG change in the power spectrum caused by the ACL rupture, and to provide evidence for the diagnosis, treatment and rehabi-litation for ACL injury as well as knee instability. Methods: Sixteen male patients, selected from the Department of Sports Medicine, Peking University Third Hospital from November 2014 to April 2015, with only ACL rupture on one side used isokinetic muscle strength testing equipment were enrolled in the study to perform unilateral active knee joint positional movement and passive knee joint positional movement tasks. EEG was recorded to compare between the affected and unaffected limb of ACL rupture patients when doing single leg movement tasks, including passive knee joint position test and active knee joint position sensation test. The target position of the active knee joint position movement task and the passive knee joint position movement task was 30 degrees of knee flexion. Results: During the passive knee joint position test, there was no significant difference in EEG power spectrum of Delta[ F (1, 15)=0.003, P=0.957, {\eta }_P^2 =0.001], Theta[F (1, 15)=0.002, P=0.962, {\eta }_P^2<0.001], Alpha[ F (1, 15)=0.002, P=0.966, {\eta }_P^2 =0.001], Beta[F (1, 15)=0.008, P=0.929, {\eta }_P^2 =0.001] at Fz, Cz, and Pz between the affected and unaffected limbs in the ACL patients. During the active knee joint position movement task, the EEG power spectrum of Delta, Theta, Alpha, Beta at Fz and Cz location, on the affected side was significant higher than on the unaffected side. Conclusion: This study compared the differences between the ACL rupture side and the unaffected side during active knee position movement task and passive knee position movement task, and identifyied the EEG changes in the power spectrum caused by the ACL rupture,It was found that the central changes caused by unilateral ACL rupture still existed during contralateral (unaffected) side movement. The EEG power spectrum of the affected side during active exercise was significantly higher than that of the unaffected side This study provides new electrophysiological evidence for the study of ACL injury.

Objective: To evaluate the relationship between postoperative knee function and the sagittal position of tibial component in unicompartmental knee arthroplasty (UKA). Methods: We retrospectively enrolled the patients who underwent UKA from January 2016 to May 2020. They were assigned into 2 groups according to postoperative posterior tibial slope (PTS): the normal PTS group (PTS≥3° and PTS<8°) and the abnormal PTS group (PTS<3° or ≥8°). The patients were followed up for at least 12 months. The postoperative Knee Society Clinical Score (KSS-C), Knee Society Functional Score (KSS-F) and knee range of motion (ROM) were compared between the two groups. Results: A total of 72 patients (82 knees) were included with 51 patients (58 knees) in PTS normal group and 21 patients (24 knees) in PTS abnormal group. All the patients were followed up with median of 23.6 months. There was no significant difference in the general data [gender, age, body mass index (BMI)], pre-operative knee range of motion, preoperative KSS-C score and KSS-F score (P > 0.01). The KSS-C score, KSS-F score, and knee range of motion significantly improved after surgery (P<0.01) for all the patients. The postoperative KSS-C score in normal PTS group (88.76±2.79) was significantly higher than the KSS-C score in abnormal PTS group (84.42±3.35, P<0.01), but no significant difference between the 2 groups was observed in postoperative KSS-F score and knee range of motion (P > 0.01). In addition, there was no correlation between the change of PTS and postoperative KSS-C score (r=-0.034, 95%CI: -0.247 to 0.186, P = 0.759), KSS-F score (r = -0.014, 95%CI: -0.238 to 0.198, P = 0.901) and knee range of motion (r= 0.045, 95%CI: -0.214 to 0.302, P = 0.686). Conclusion: The posterior tibial slope between 3° and <8° can be recommended to improve knee joint function in mobile UKA, and excessive or insufficient PTS should be avoided.

Objective: To evaluate the effects of two different femoral cortical suspension devices (fixation loop and adjustable loop) on tunnel widening and knee function in patients following anterior cruciate ligament reconstruction for 12 months. Methods: A total of 60 patients who had undergone anterior cruciate ligament reconstruction were included in this study. According to the length of the loop(n)[n= total length of loop-(total length of femoral tunnel-total length of coarse tunnel)] in the rough bone tunnel, the patients were divided into A (adjustable loop was 0 mm in the coarse bone tunnel), B (fixation loop was greater than 0 mm and less than or equal to 10 mm in the coarse bone tunnel) and C (fixation loop was greater than 10 mm in the coarse bone tunnel) groups, of which 11 cases were in group A, 27 cases in group B and 22 cases in group C. In the three-dimensional reconstruction of the knee joint with multi-slice spiral CT, the widening of the bone tunnel in the three groups was compared. At the same time, IKDC, Lysholm and Tegner scores of the patients in the three groups were compared. Results: There were differences in the widening degree of the femoral canal among groups A, B and C, and the median difference of the widening degree of the femoral tunnel 12 months and immediately after the surgery was A<B<C. The difference of femoral canal widening in group A was significantly different from that in groups B and C (P<0.05).According to the linear regression the relationship between the difference of the width of the femoral canal and the change of the length (n) of the loop in the coarse canal, it was found that there was a linear relationship between the value of n and the difference of the width of the bone canal. With the increase of the value of n, the difference of the width of the bone canal gradually became larger. The median difference of the width of the middle and superior tunnel was negative, while the median difference of the width of the middle and inferior tunnel was positive. During the follow-up, we found that there were no statistical differences in IKDC, Lysholm and Tegner scores among the three groups one year after surgery (P>0.05). Conclusion: Twelve months after surgery, compared with group B (fixed loop group) and group C (fixed loop group), group A (adjustable loop group) had less bone tunnel widening.In groups A, B and C, as the length of the loop in coarse bone tunnel gradually increased, the width of bone tunnel became more significant. At the end of 12 months follow-up after anterior cruciate ligament reconstruction, the medial and inferior femoral tunnel was significantly wider than immediately after surgery, and the medial and superior femoral tunnel had gradually begun to undergo tendon-bone healing. There was no significant difference in knee function scores among groups A, B, and C in the follow-up 12 months after surgery.

Objective: To bring forward an arthroscopic classification of the popliteal hiatus of the lateral meniscus (PHLM) tears and to assess the effects of arthroscopic all-inside repair with suture hook in management of such injuries. Methods: This study involved 146 patients who underwent arthroscopic operation because of PHLM tears from April 2014 to October 2017, eliminating the patients who had discoid lateral meniscus. There were 81 males and 65 females, with 54 left knees and 92 right knees. The average ages were (34.7±3.7) years. Among the selected participants, there were 107 patients with anterior cruciate ligament (ACL) injuries, 39 patients with medial collateral ligament (MCL) injuries, and 48 patients with medial meniscus tears. The average preoperative Lysholm and International Knee Documentation Committee (IKDC) scores were 57.7±9.2 and 54.1±8.9, respectively. The arthroscopic classification was based on the extent and degree of PHLM tears and using the arthroscopic all-inside repair with suture hook for such injuries. For the patients associated with ACL injuries, the ipsilateral autograft hamstring tendons use as the reconstruction graft for single bundle ACL reconstructions. The suture anchors were used for treatment of MCL Ⅲ injuries, and the arthroscopic all-inside repair for medial meniscus tears. Results: A total of 146 PHLM tears in 146 patients were divided into type Ⅰ (tears not involved in popliteus tendon incisura; n=86, 58.9%), type Ⅱ (tears involved in popliteomeniscal fascicles; n=36, 24.7%), and type Ⅲ (tears involved in popliteus tendon incisura; n=24, 16.4%). For type Ⅰ, there were three subtypes, including type Ⅰa: longitudinal tear (n=53, 61.6%), type Ⅰb: horizontal tear (n=27, 31.4%), and type Ⅰc: radial tear (n=6, 7.0%). For type Ⅱ, there were also three subtypes, including type Ⅱa: anterosuperior popliteomeniscal fascicle tear (n=5, 13.9%), type Ⅱb: posterosuperior popliteomeniscal fascicle tear (n=20, 55.6%), and type Ⅱc: both tears (n=11, 30.6%). For type Ⅲ, there were two subtypes, including type Ⅲa: horizontal tear (n=9, 37.5%), type Ⅲb: radial tear (n=15, 62.5%). In the follow-up for an average of 15.3±2.6 months, all the patients had done well with significantly improved Lysholm (84.6±14.3) and IKDC (83.2±12.8) scores at the end of the last follow-up relative to preoperative scores (P>0.01). Conclusion: We propose that it is possible to classify lateral meniscus tears at the popliteal hiatus region for three types, which can summarize the injury characteristics of this area. The arthroscopic all-inside repair with suture hook for the PHLM tears can avoid stitching to popliteal tendon or narrowing popliteal hiatus and have satisfactory clinical results.

Objective: To introduce an arthroscopic “inlay” Bristow procedure based on the Mortise-Tenon joint structure concept using suture button fixation, and to evaluate its clinical and radiology results postoperatively with a minimal 3-year follow-up. Methods: A total of 56 patients who received arthroscopic “inlay” Bristow procedure with suture button fixation between June 2015 to June 2016 were eventually enrolled in this study. Radiological assessment on the 3D CT scan was performed preoperatively, immediately after operation, and postoperatively at the end of 3 months, 6 months and the final follow-up. Complications postoperatively were also recorded. Results: A total of 56 patients were finally included in this study. The mean follow-up time was (36.1±3.7) months. Coracoid grafts (middle point) were positioned at about 4 o’clock (123.8°±12.3°) in the En-face view. In the axial view, 95% (53/56) of the grafts positioning were measured as flush, 5% (3/56) as medial. Bone union rate was 96.4% at the final follow-up. At the end of 3 months, 6 months, and the final follow-up, the length of the coracoid graft was 96.9%±4.9%, 91.9%±6.2%, and 91.6%±6.6% of the immediate postoperative length, respectively. Compared with the immediate postoperative length, the length measured at the end of 3 months shortened not significantly (t=2.12, P>0.05). The coracoid graft shortened more pronouncedly 6 months postoperatively (t=4.98, P<0.05) and then remained almost constant over time (t=-0.75, P>0.05), with all grafted coracoid graft retaining more than 90% of their initial length by the 3-year follow-up. And new bone formation at the junction between the coracoid graft and glenoid neck in the axial view were obviously noted in 25 cases. The quantitative evaluation showed that the glenoid area in En-face view was significantly increased at the final follow-up than that immediately after surgery [(9.72±1.22) cm² vs. (9.42±1.11) cm²]. No degenerative changes were noted on CT images in all the patients at the final follow-up. Conclusion: This study reported a series of “inlay” Bristow procedure with suture button fixation for recurrent shoulder dislocation, providing satisfactory union rate and excellent graft positioning. And using suture button fixation instead of screw can reduce osteolysis and complications related to hardware implantation. Moreover, the bone remodeling between the coracoid process and glenoid could be beneficial to restoring the anterior stability of shoulder joint in a long term follow-up.

Objective: To analyze the preoperative pulmonary function in rotator cuff injury patients and the possible influencing factors. Methods: All the rotator cuff surgery patients who underwent pre-operative pulmonary function examination in Peking University Third Hospital from Jan. 2020 to Jun. 2020 were retrospectively reviewed. Their perioperative medical records and main parameters of pulmonary function were collected from database management system, and their gender, age, body mass index (BMI), smoking history, time from injury, visual analogue scale (VAS) and other factors impacting on preoperative pulmonary function were studied. Results: Twenty-nine patients with rotator cuff injury were included, among whom 1 patient was reported to have restrictive ventilation dysfunction and 2 patients to have obstructive ventilation dysfunction. All the three patients denied the history of respiratory diseases, and had no respiratory symptoms. In all enrolled patients, the mean forced expiratory volume in one second (FEV1)/ forced vital capacity (FVC) was 79.2%±5.9%, and the mean VAS pain score was 3.66±1.26. In addition, the dynamic pulmonary functions (FVC, FEV1) were reduced in more than half of the elderly, and the total lung capacity (TLC) was lower than the estimated value in 2/3 of the elderly. There were significant differences in three main indexes of pulmonary functions between genders, and the percentage of the estimated TLC between normal BMI group (18 kg/m²<BMI<24 kg/m²) and overweight/obesity group (BMI≥24 kg/m²) was significantly different. Based on the injury time longer than 1 year or not, the results indicated that FVC and TLC were significantly different between the two groups. Conclusion: In addition to gender and age, time from injury and severity of pain, as well as overweight/obesity, may influence pulmonary function outcomes in the elderly rotator cuff patients. Targeted intervention can be carried out on these factors before surgery. Preoperative lung function test can be used as one of the basic evaluation indexes for respiratory training and rehabilitation of patients.

Objective: To analyze the effects of visual restoration after cataract surgery on plantar pressure and biomechanics of foot in elder individuals. Methods: Thirty-two patients [male/female 5/27, (70.1±5.2) years old] with age-related cataract were recruited between October 2016 and December 2019. The footscan system was employed to record the data of plantar pressure during level walking before and 1-month after the cataract surgery. Parameters of peak pressure (PP), impulse (I), pressure-time integral (PTI) and time to peak pressure (TPP) from the regions of the 1st toe (T1), 2nd to 5th toes (T2-5), 1st to 5th metatarsal heads (M1-M5), midfoot (MF), medial hindfoot (HM) and lateral hindfoot (HL) were analyzed respectively. Results: Post-operatively, the visual function was effectively reconstructed with improved visual acuity in both eyes (Z=-4.878, -4.801; P<0.001). The PP (t=2.266, P=0.031) and I (t=2.152, P=0.039) values in M2 region on the dominant side (right foot) increased statistically at post-operative phase, while the changes of pressure and temporal para-meters in other regions remained stable. There was laterality in plantar pressure at pre-operative phase, manifested as greater PP values in M1, M2, MF, and HM regions on the dominant sides (t=-2.414, -2.478, -2.144, -5.269; P<0.05), greater PP values in T1, M3, M5 and HL regions on the non-dominant sides (t=4.830, 3.155, 2.686, 3.683; P<0.05), greater I values in M1, MF, and HM regions on the dominant sides (t=-2.380, -2.185, -5.320; P<0.05) and greater I values in T1, M3, M5 and HL regions on the non-dominant sides (t=4.489, 2.247, 2.838, 3.992; P<0.05). post-operatively, the pressure tended to be compatible between the two sides in regions of M3 and MF, while the magnitude of laterality in regions of M1 (Z_PP△= -2.721, P=0.007; Z_I△=-2.581, P=0.010), M2 (Z_PP△=-2.674, P=0.007; Z_I△=-2.375, P=0.018) and M5 (Z_PP△=1.991, P=0.046; Z_I△=2.150, P=0.032) was further increased. Conclusion: Changes in plantar pressure after cataract surgery were characterized as increased pressure in the 2nd metatarsal head area on the dominant side. Visual restoration might intensify the laterality in the medial of forefoot on the dominant side and the lateral of forefoot on the non-dominant side.

Objective: To investigate the clinical features and prognosis of acute myeloid leukemia (AML) patients with the mixed lineage leukemia (MLL) gene rearrangements AF6 (MLL-AF6) positive. Methods: In the study, 11 patients who were newly diagnosed with MLL-AF6 positive AML were analyzed retrospectively, related literature was reviewed to clarify the clinical features and prognosis of MLL-AF6 positive patients. Results: Among the 11 patients, there were 6 males and 5 females, with a median age of 36 years. Six patients were diagnosed with AML M5 and five with M4 according to FAB classification (French-American-British classification systems). Gingival swelling and pain occurred in 6 cases and fever occurred in 5 cases. At first diagnosis, the median white blood cells were 55.5×10⁹/L. Immunotype showed the expression of myeloid/monocyte and early stem cell series antigens. The expression level of MLL-AF6 fusion gene (real-time quantitative PCR) was 14.2%-214.5%, and 6/11 cases (54.5%) were associated with high EVI1 gene expression. Mutations of KRAS, TET2, ASXL1, TP53, DNMT3A, and FLT3-ITD were detected by next generation sequencing (NGS) in 4 patients. Chromosome G banding examination showed that 2 cases were t(6;11)(q27,q23) with complex karyotype abnormality, 4 cases with +8 abnormality and 2 cases with normal karyotype. Hematological complete remission (CR) was achieved in 8/11 patients (72.7%) after conventional induction chemotherapy, and primary drug resistance was observed in 3 patients. Two of the eight patients with CR were negative for minimal residual disease (MRD), with a median CR duration of 4.5 months. Two patients with positive MRD and three patients with refractory recurrence underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), but all died due to leukemia progression. At the end of follow-up on December 1, 2019, 2 patients were alive and 9 died, with median survival time of 9 months. Conclusion: The AML patients with MLL-AF6 positive were mostly young, the majority of FAB types were M4 and M5, and most of the patients often had fever as the first symptom, with increased white blood cells, accompanied by organ infiltration, and high EVI1 gene expression. The hematological remission rate of routine chemotherapy is not low, but it is difficult to achieve molecular remission, most of which have early recurrence. Early allo-HSCT in a molecular negative state may prolong the CR duration.

Objective: To investigate the relationship between marked hyperferritinemia (MHF) and hemophagocytic lymphohistiocytosis(HLH). Methods: The clinical data of 123 patients with MHF admitted to Peking University People’s Hospital from January 2017 to September 2018 were collected, including demographics, baseline characteristics, signs and symptoms, blood routine, blood biochemistry, coagulation function parameters, such as prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fib), d-dimer (D-D), fibrin degradation product (FDP), blood ferritin, natural killer (NK) cell activity, soluble interleukin (IL)-2 receptor and bone marrow examination. According to the diagnosis of HLH, the patients were divided into HLH group and non HLH group. The patients were divided into death group and survival group according to the 3-month follow-up results. The groups were compared and statistically analyzed. Results: In the 123 patients with MHF, the average age was (44.2±17.4) years with a male/female ratio of 1.3 ∶1. The most common causes were hematolo-gic malignancies, rheumatologic and inflammatory disorders, iron overload, and HLH. HLH was enriched as the ferritin increased, and the HLH ratios were 28.8%, 40.0%, 54.5%, 50.0%, 50.0% in ferritin value of 10 000-19 999, 20 000-29 999, 30 000-39 999, 40 000-49 999 μg/L,more than 50 000 μg/L respectively. There were 46 cases of HLH, among which 15 cases were secondary to malignancies,14 cases secondary to rheumatologic disorders, 2 cases secondary to infection, and 15 cases with no clear precipitating cause. There were significant differences between the HLH group and non-HLH group in hepatomegaly, splenomegaly, lymphadenectasis, albumin (ALB), fibrinogen(Fib), P<0.05, and no significant differences in age, gender, fever, disturbance of consciousness, ferritin level on presentation, maximum ferritin level, cytopenia in 2 or more cell lines, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), direct bilirubin (DBIL), triglyceride (TG), coagulation parameters (PT, APTT, D-D, FDP, exception of Fib), and mortality rate (P>0.05). There were significant differences between the death group and survival group in disturbance of consciousness, platelet count, PT, TBIL, and DBIL (P<0.05), but no significant differences in age, gender, fever, hepatomegaly, splenomegaly, lymphadenectasis, ferritin level on presentation, maximum ferritin level, neutrophils, hemoglobin, ALT, AST, ALB, TG, coagulation parameters (Fib, APTT, D-D, FDP, exception of PT) and the HLH ratio (P>0.05). Conclusion: HLH was enriched as the ferritin increased, but marked hyperferritinemia was not specific for HLH in adults.

Objective: To investigate the clinical characteristics, diagnosis and treatment of renal cell carcinoma with urinary tract tumor thrombus. Methods: From January 1, 2015 to December 31, 2019, patients with renal cell carcinoma complicated with urinary tract tumor thrombus who were hospitalized in the Peking University Third Hospital and Beijing Friendship Hospital, Capital Medical University were retrospectively analyzed. Meanwhile, we reviewed the literature, and the reported patients of renal cell carcinoma with urinary tract tumor thrombus were also included in our study. The basic information, clinical manifestations, treatment, pathological characteristics and follow-ups of all the patients were analyzed. Results: In our study, 6 patients from the two hospitals and 16 patients from previous literature reports were included. There were 13 males and 9 females with an average age of 54.7 years (22-79 years). Fifteen patients had renal cell carcinoma on the left side, 6 on the right side, and 1 on the unknown side. Gross hematuria was the most common chief complaint, including 18 patients. One patient complained of weight loss, 1 patient complained of microscopic hematuria, and 1 patient was found by ultrasound examination. Tumor thrombus was classified as grade Ⅰ in 9 cases (the tumor embolus protruded into the renal pelvis, but did not reach the ureteropelvic junction), grade Ⅱ in 10 cases (the tumor embolus protruded into the ureter, but not into the bladder), and grade Ⅲ in 3 cases (the tumor embolus passed through the ureter and protruded into the bladder). Only 11 patients were diagnosed with renal cell carcinoma before operation. Radical nephrectomy was performed in 9 cases and nephroureterectomy in 12 cases. In pathological diagnosis, there were 15 cases of clear cell renal cell carcinoma, 1 case of papillary renal cell carcinoma, 1 case of chromophobe cell carcinoma, 1 case of mixed cell renal cell carcinoma, 4 cases of renal cell carcinoma with undetermined classification. Eleven patients were followed up for 3-31 months, and 3 patients had lung metastasis within 6 months. Conclusion: Renal cell carcinoma with urinary tract tumor thrombus is rare in clinic. It needs to be differentiated from renal pelvis carcinoma in diagnosis. The treatment principle can refer to general renal carcinoma. For locally advanced cases, complete resection is the best treatment, and its oncological prognosis needs more long-term and large-scale follow-up observation.

Objective: To investigate the clinical and serological features of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) overlap syndrome (Rhupus syndrome). Methods: We retrospectively reviewed the medical records of 21 patients with Rhupus syndrome who were hospitalized at Department of Rheumatology and Immunology, People’s Hospital of Xinjiang Uygur Autonomous Region between January 2010 and January 2018. We compared the joint involvement, autoantibodies and clinical manifestations of Rhupus syndrome with 81 cases of RA-alone and 51 cases of SLE-alone. Results: In 21 patients with Rhupus syndrome, there are 3 males and 18 females. Compared with the SLE-alone group, the patients with Rhupus syndrome were older [(49.43±11.66) vs. (40.59±12.73), P=0.008]. The median age of the patients with Rhupus syndrome at RA onset was significantly younger than that of the RA-alone patients [(32.58±11.14) vs. (43.11±11.83), P=0.010]. Of the 21 patients with Rhupus syndrome, the initial diagnosis was RA in 57% (12/21), except 2 male patients, the other 10 patients with SLE manifestations were menopause, the mean age of amenorrhea or menopause was (44.30±5.33) (36-50) years. The mean interval between the onset of SLE and RA was 10.83 years. Two patients started with SLE manifestations. Moreover, both diseases simultaneously developed in 33.3% of the patients. Except one male patient, 3 patients were in menopause stage when RA and SLE appeared. The positive rate of specific antibody Rhupus syndrome was similar to that of RA. Renal damage was relatively rare in SLE related manifestations, but the incidence of interstitial lung disease was higher. There were no significant differences in the prevalence of complements C3 and C4, antinuclear antibody (ANA), anti-double-stranded DNA (anti-dsDNA), anti-SSA or anti-SSB antibody between the Rhupus syndrome and SLE-alone group. Conclusion: Rhupus syndrome is an overlapping syndrome in which RA and SLE coexist. Most of the diseases occur in RA and the related manifestations of RA are more serious than those of SLE. The incidence of Rhupus syndrome may be related to the change of sex hormone levels.

Objective: To investigate the application value of serum 25-hydroxy vitamin D [25(OH)D] in systemic lupus erythematosus (SLE). Methods: Data of 158 patients with SLE in Department of Rheumatology and Immunology in the People’s Hospital of Xinjiang Uygur Autonomous Region from July 2016 to July 2019. All the SLE patients were divided into two groups by SLE scores of the disease activity index (SLEADI): 59 cases of active group (SLEADI>4), 99 cases of non-active group (SLEDAI ≤4). Fifty healthy people were selected as healthy control group. The patients’ general information and their laboratory data including serum 25(OH)D levels were collected. Statistical methods used were t-test, Spearman’s correalation analysis and Logistic regression analysis. Results: (1) A total of 208 cases were included in this study. The level of 25(OH)D in SLE group [10.4(5.6,15.8) μg/L] was significantly lower than that in healthy control group [25.5(22.8,32.3) μg/L, P<0.01]. 25(OH)D level in active SLE patients [6.2(3.7,13.8) μg/L] was significantly lower than that in remission SLE patients [12.3(7.2,16.7) μg/L, P<0.01]. The serum 25(OH)D level in lupus nephritis [6.7 (4.4, 12.9) μg/L] was significantly lower than that in SLE without renal involvement [13.3 (7.4, 18.7) μg/L, P<0.01]. (2) A significant negative correlation was demonstrated between the serum level of 25(OH)D and SLEDAI (r=-0.35,P<0.01), and the 24h urinary protein excretion (r=-0.39, P<0.01).Positive correlation was demonstrated between the serum level of 25(OH)D and C3 that decreased (r=0.249, P<0.05). (3) Univariate analysis showed anti- dsDNA antibodies(ds-DNA), anti-Sm antibodies(Sm), IgG, C3, C4, erythrocyte sedimentation rate (ESR), 24h urinary protein quantification(24h-pro) and 25(OH)D were associated with disease activity in the SLE patients; Multivariate Logistic regression analysis showed that 25(OH)D was associated with the disease activity of the lupus patients. Conclusion: The decrease of vitamin D level is related to the disease activity of SLE patients, and may be related to lupus nephritis, which plays an important role in the occurrence and development of SLE.

Objective: With the rapid development of sleep medicine, there are various methods for detecting sleep diseases. This study compared the correlation between the lightweight watch-type sleep monitor (Actiwatch) and the “gold standard” polysomnography (PSG) in the Chinese population, in order to provide a basis for clinical application. Methods: From August 2018 to December 2019, 121 subjects who simultaneously performed sleep breathing monitoring (PSG) and wearing a watch-type sleep monitor (Actiwatch) in the Sleep Center of Peking University People’s Hospital were enrolled. All subjects received PSG and Actiwatch at the same time, and filled out the sleep diary next morning. Monitoring indicators were collected for linear correlation analysis and paired t test to compare the differences. Results: Under low sensitivity conditions, the correlation coefficient of total sleep time (TST) between PSG and Actiwatch was 0.53 (P<0.05). Paired t test analysis showed that there was no significant difference between the TSTs of Actiwatch and PSG (t=-0.890, P=0.36). According to age stratification, the smaller the age, the stronger the correlation between the TSTs of Actiwatch and PSG, and the coefficient could be up to 0.92 (P<0.05). Paired t test showed that there was no significant difference between them (t=-1.057, P=0.35). According to the stratification by diagnosis, the correlation coefficient between the TSTs of Actiwatch and PSG in normal PSG group could be as high as 0.79 (P<0.05), the results of paired t test showed that there was no significant difference between the TSTs of Actiwatch and PSG in normal PSG group (t=-0.784, P=0.44). Conclusion: As a wearable home recorder, when the analysis parameters of Actiwatch were set as low sensitivity, PSG and Actiwatch had the highest TST correlation. The younger the age, the stronger correlation between the TSTs of Actiwatch and PSG. The PSG and Actiwatch subjects with normal PSG presentation had a higher TST correlation.

Objective: To compare well-known preload dynamic parameters intraoperatively including stroke volume variation (SVV), pulse pressure variation (PPV), and plethysmographic variability index (PVI) in children who underwent craniotomy for epileptogenic lesion excision. Methods: A total of 30 children aged 0 to 14 years undergoing craniotomy for intracranial epileptogenic lesion excision were enrolled. During surgery, we measured PPV, SVV (measured by the Flotrac/Vigileo device), and PVI (measured by the Masimo Radical-7 monitor) simultaneously and continuously. Preload dynamic parameter measurements were collected at predefined steps: after induction of anesthesia, during opening the skull, intraoperative electroencephalogram monitoring, excision of epileptogenic lesion, skull closure, at the end of the operation. After exclusion of outliers, agreement among SVV, PPV, and PVI was assessed using repeated measures of Bland-Altman approach. The 4-quadrant and polar plot techniques were used to assess the trending ability among the changes in the three parameters. Results: The mean SVV, PPV, and PVI were 8%±2%, 10%±3%, and 15%±7%, respectively during surgery. We analyzed a total of 834 paired measurements (3 to 8 data sets for each phase per patient). Repeated measures Bland-Altman analysis identified a bias of -2.3 and 95% confidence intervals between -1.9 and -2.7 (95% limits of agreement between -6.0 and 1.5) between PPV and SVV, showing significant correlation at all periods. The bias between PPV and PVI was -5.0 with 95% limits of agreement between -20.5 and 10.5, and that between SVV and PVI was -7.5 with 95% limits of agreement between -22.7 and 7.8, both not showing significant correlation. Reflected by 4-quadrant plots, the con-cordance rates showing the trending ability between the changes in PPV and SVV, PPV and PVI, SVV and PVI were 88.6%, 50.4%, and 50.1%, respectively. The concordance rate between PPV and SVV was higher (92.7%) in children aged less than 3 years compared with those aged 3 and more than 3 years. The mean angular bias, radial limits of agreement, and angular concordance rate in the polar analysis were not clinically acceptable in the changes between arterial pressure waveform-based parameters and volume-based PVI (PPV vs. PVI: angular mean bias 8.4°, angular concordance rate 29.9%; SVV vs. PVI: angular mean bias 2.4°, angular concordance rate 29.1%). There was a high concordance between the two arterial pressure waveform-based parameters reflected by the polar plot (angular mean bias -0.22°, angular concordance rate 86.6%). Conclusion: PPV can be viewed as a surrogate for SVV, especially in children aged less than 3 years. The agreement between arterial pressure waveform-based preload parameters (PPV and SVV) and PVI is poor and these two should not be considered interchangeable. Attempt to combine PVI and PPV for improving the anesthesiologist’s ability to monitor cardiac preload in major pediatric surgery is warranted.

Objective: To analyze the changes and characteristics of pediatric outpatient visits in a general hospital before and after the coronavirus disease (COVID-19) epidemic. Methods: Based on the registration data of pediatric outpatient visits in the information system (HIS)of Beijing Tsinghua Changgung Hospital, from January 1 2018 to December 31 2020, aged 0 to 16 years,we analyzed the changes of outpatient visits before and after the epidemic, focusing on respiratory infection including influenza. The relationship between the outpatient visits and age and quarterly distribution were also studied. Results: (1)Respiratory infection accounted for the majority of outpatient visits in 2018 and 2019 (60.6% and 60.5%, respectively). Non-respiratory infection accounted for the main proportion of outpatient visits in 2020, while respiratory infection accounted for only 47.4%. Annual respiratory infection visits, respiratory infectious diseases visits especially influenza visits all decreased significantly in 2020 compared with that in 2018 and 2019 (P<0.05). (2)Respiratory infection visits were highest in the infant group, lowest in the school age group (P<0.05) and highest in the fourth quarter each year. It decreased significantly in the second quarter of 2020 with statistical significance when compared with the other quarters of 2020(P<0.05). (3)Influenza accounted for the highest proportion of respiratory infectious diseases visits in each year. It was highest in first quarter, which was significantly different from the other quarters of the year (P<0.05). There were different distributions of influenza visits throughout 2018 and 2019, while it was only distributed in the first quarter and 99% in January in 2020. Conclusion: The respiratory infection and influenza visits have decreased significantly in our pediatric outpatient department after the COVID-19 epidemic,which is considered closely related to the lifestyle and personal protection after the epidemic. It is recommended that health education on respiratory infection and influenza prevention should be strengthened, especially in winter and spring, to promote the development of good respiratory and hand hygiene habits.

Objective: Distal hereditary motor neuropathy (dHMN) comprises a heterogeneous group of inherited disorders associated with neurodegeneration of motor nerves and neurons, mainly charac-terized by progressive atrophy and weakness of distal muscle without clinical or electrophysiological sensory abnormalities. To improve the recognition and diagnosis of the disease, we summarized the clinical manifestations, electrophysiological, pathological, and genetic characteristics in eight patients with dHMN. Methods: Eight probands from different families diagnosed with dHMN were recruited in this study between June 2018 and April 2019 at Peking University People’s Hospital. Eight patients underwent complete neurological examination and standard electrophysiological examinations. The clinical criteria were consistent with the patients presenting with a pure motor neuropathy with no sensory changes on electrophysiology. The detailed clinical symptoms, neurophysiological examinations, pathological features and gene mutations were analyzed retrospectively. Genetic testing was performed on the eight patients using targeted next-generation sequencing panel for inherited neuromuscular disorder and was combined with segregation analysis. Results: The age of onset ranged between 11 and 64 years (median 39.5 years) in our dHMN patients. All the cases showed a slowly progressive disease course, mainly characterized by distal limb muscle weakness and atrophy. The motor nerve conduction revealed decreased compound muscle action potential amplitude and velocity, while the sensory nerve conduction velocities and action potentials were not affected. Needle electromyography indicated neurogenic chronic denervation in all patients. Muscle biopsy performed in two patients demonstrated neurogenic skeletal muscle damage. Sural nerve biopsy was performed in one patient, Semithin sections shows relatively normal density and structure of large myelinated fibers, except very few fibers with thin myelin sheaths, which suggested very mild sensory nerve involvement. Eight different genes known to be associated with dHMN were identified in the patients by next-generation sequencing, pathogenic dHMN mutations were identified in three genes, and the detection rate of confirmed genetic diagnosis of dHMN was 37.5% (3/8). Whereas five variants of uncertain significance (VUS) were identified, among which two novel variants co-segregated the phenotype. Conclusion: dHMN is a group of inherited peripheral neuropathies with great clinical and genetic heterogeneity. Next-generation sequencing is widely used to discover pathogenic genes in patients with dHMN, but more than half of the patients still remain genetically unknown.

Objective: To observe the efficacy and safety of Nocardia rubra cell wall skeleton (Nr-CWS) for the treatment of erosive oral lichen planus (EOLP). Methods: Sixty patients with clinically and pathologically diagnosed EOLP were randomly divided into the experimental group and control group according to the random number. Patients in the experimental group were treated with lyophilized powder containing Nr-CWS combined with normal saline. Patients in the control group received topical placebo without Nr-CWS combined with normal saline. Changes in the EOLP lesion area and the patient’s pain level were recorded at the timepoints of weeks 1, 2, and 4 after the two different treatments, respectively. The changes of the patient’s REU scoring system (reticulation, erythema, ulceration), the visual analogue scale and the oral health impact score (OHIP-14) were compared between the experimental group and control group after treatment, and the safety indicators of the two groups at the initial diagnosis and after 4 weeks’ treatment were also observed, respectively. Results: Totally, 62 patients with clinically and pathologically diagnosed EOLP were enrolled, 2 of whom were lost to the follow-up, with 31 in the experimental group, and 29 in the control group. The mean age of the experimental group and control group were (52.9±12.4) years and (54.07±12.40) years, respectively. There was no significant difference in the oral periodontal index between the experimental group and control group. In the experimental group, the erosive area of oral lichen planus was significantly reduced 1, 2, and 4 weeks after the Nr-CWS’s treatment (P<0.05), the reduction rate was 81.75%, the patient’s pain index was also decreased (P<0.05), and in addition, the OHIP-14 was reduced (P<0.05). The changes of the REU scoring system, the visual analogue scale and the OHIP-14 were significantly different between the experimental group and control group after treatment. There was no significant difference in the safety index between the two groups. Conclusion: The priliminary data show that the Nr-CWS is effective and safe to treat EOLP.

Objective: To analyze the clinical curative effect after 5-year follow-up of single tooth implant-supported restorations in the posterior region. Methods: In the study, patients with single tooth implant-supported restorations in the posterior region after loading 5-year in the Second Clinical Division of Peking University School and Hospital of Stomatology from October 2005 to May 2010 was enrolled. The implant survival rate, prosthetic conditions (including the structural integrity or loosening of the prosthesis, the retention of the materials used to fill access holes of screw-retained implant crowns, loosening or fractures of the implant abutment or screw) and marginal bone lever level around implants were determined by clinical and radiographic examination. Results: The study was composed of 215 patients, the mean age was 48.6 years (range: 27 to 71), and 321 soft tissue implants were inserted. There were 9 implants loose and lost during the visit, the cumulative success rate was 97.2%. In the 312 remaining implants, 120 implants were placed in the upper jaws (38.5%) and 192 in the lower jaws (61.5%). Three different diameters as 3.3 mm (5 implants), 4.1 mm (115 implants) and 4.8 mm (192 implants) and three different lengths as 8 mm (21 implants), 10 mm (206 implants) and 12 mm (85 implants) were used, respectively. 277 (88.8%) cement-retained and 35 (11.2%) screw-retained implant-supported single crowns were made. The marginal bone loss (MBL) around dental implants after loading 5 years in the mesial and distal sides were (0.73±0.25) mm and (0.78±0.26) mm, respectively. There was no significant difference among MBL and bone quality, implant type, angle of abutment, prosthodontic type, crown-to-implant ratio, gender, and age of the patients (P>0.05). The major mechanical complications after restoration involved loosening (8.6%) and fracture (2.9%) of the crown retainer screw, loss of resin covering the screw (11.4%), and the most frequent mechanical complications were loss of crown retention (14.1%) and fracture of porcelain (13.8%). The incidence of loss of crown retention was correlated with insufficient clinical crown height or using angle abutment (P<0.05). Conclusion: After loading 5 years, the bone level around the soft-tissue-implant placed in posterior region was stable. To minimize the frequency of mechanical complications after restoration, protocols must be established from diagnosis to the completion of treatment and follow up of implant-supported prostheses, especially in terms of adequate technical steps and careful radiographic evaluation of the components.

Objective: To evaluate the morphology accuracy of direct occlusal veneer using two types of modified stamp-technique, comparing the results of two types of stamp and different composite resin. Methods: Model scanner was used to get the original data from the standard resin teeth in plastic model. Two types of stamps were made: solid silicon stamp and transparent silicon stamp. In the study, 54 resin tooth were randomly divided into 9 groups: Groups 1-8 were restored by direct composite resin, using general and bulk-filled composite resin in occlusal veneer (1 mm or 2 mm) with two types of stamp-technique (the solid silicon, and the transparent silicon), and the control group was restored by indirect way using CAD/CAM composite resin restoration by biocopy technique to mimic the original shape of the teeth. After the resin teeth were prepared for occlusal veneer, the direct and indirect composite resins were restored. After the restoration was finished, the data were obtained again by the same model scanner in the plastic model. 3D comparisons were made using the original and restoration data, the average difference and the root mean square of difference (RMS) were recoded from the software. The RMS of all the groups were analyzed using one way ANOVA (α=0.05). Results: The RMS of occlusal surface in solid silicon stamp group was (0.136±0.031) mm, in transparent silicon group was (0.130±0.024) mm, and in control group was (0.130±0.009) mm. There were no significant difference. While the RMS of buccal/lingual surface in solid silicon stamp group was the smallest [(0.135±0.020) mm, P<0.05], and in transparent silicon group it was (0.147±0.021) mm, and control group (0.153±0.014) mm. The general composite resin using the two types of stamp had the largest occlusal RMS in 2 mm occlusal veneer, which were significantly larger than control group (P<0.05). Conclusion: The direct occlusal veneer using two types of modified “stamp-technique” had relatively good morphology accuracy. Direct occlusal veneer using bulk-filled composite resin made with two types of stamp technique had even more accurate morphology than using general composite resin. The solid silicon stamp had a better morphology accuracy in buccal/lingual surface than the transparent silicon stamp.

Objective: To analyze the biomechanical mechanism of mandibular symphyseal fracture combined with bilateral intracapsular condylar fractures using finite element analysis (FEA). Methods: Maxillofacial CT scans and temporomandibular joint (TMJ) MRI were performed on a young male with normal mandible, no wisdom teeth and no history of TMJ diseases. The three-dimensional finite element model of mandible was established by Mimics and ANSYS based on the CT and MRI data. The stress distributions of mandible with different angles of traumatic loads applied on the symphyseal region were analyzed. Besides, two models with or without disc, two working conditions in occlusal or non-occlusal status were established, respectively, and the differences of stress distribution between them were compared. Results: A three-dimensional finite element model of mandible including TMJ was established successfully with the geometry and mechanical properties to reproduce a normal mandibular structure. Following a blow to the mandibular symphysis with different angles, stress concentration areas were mainly located at condyle, anterior border of ramus and symphyseal region under all conditions. The maximum equivalent stress always appeared on condylar articular surface. As the angle between the external force and the horizontal plane gradually increased from 0° to 60°, the stress on the mandible gradually concentrated to symphysis and bilateral condyle. However, when the angle between the external force and the horizontal plane exceeded 60°, the stress tended to disperse to other parts of the mandible. Compared with the condition without simulating the disc, the stress distribution of articular surface and condylar neck decreased significantly when the disc was present. Compared with non-occlusal status, the stress on the mandible in occlusal status mainly distributed on the occlusal surface, and no stress concentration was found in other parts of the mandible. Conclusion: When the direction of external force is 60° from the horizontal plane, the stress distribution mainly concentrates on symphyseal region and bilateral condylar surface, which explains the occurrence of symphyseal fracture and intracapsular condylar fracture. The stress distribution of condyle (including articular surface and condylar neck) decreases significantly in the presence of arti-cular disc and in stable occlusal status when mandibular symphysis is under traumatic force.

Objective: To measure the three-dimensional morphology of the labial supraosseous gingiva (SOG) and the thickness of related labial bone in maxillary anterior teeth of periodontally healthy Han nationality youth using soft tissue indirect imaging cone-beam computed tomography (CBCT). Methods: Twenty-five periodontally healthy subjects (11 males and 14 females) with 150 maxillary anterior teeth were involved in this study. A special impression with radiopaque material including the maxillary teeth was made, then a CBCT scan with the elastomeric matrix in position was taken for each subject. The imaging data were generated and transferred to a volumetric imaging software in which three-dimensional reconstruction was conducted and the image analyses were carried out. Measurements were made at the site of labial center of the maxillary anterior teeth. The height of the SOG, the distance between cemento-enamel junction (CEJ) and bone crest, the gingival thickness at the CEJ, and the thickness of bone 2 mm below the labial bone crest were measured and the correlation analysis between the parameters was made. All the data analyses were performed using SPSS 22.0. The data were analyzed with ANVOA and Pearson correlation tests with the significance level at α=0.05. Results: The mean SOG values were (3.49±0.70) mm, (3.48±0.81) mm, and (3.54±0.67) mm for central incisors, lateral incisors and canines, respectively. There were no statistically significant differences among the different sites (P>0.05). The mean gingival thickness values were (1.45±0.23) mm, (1.13±0.24) mm, (1.14±0.22) mm for central incisors, lateral incisors and canines, respectively. The gingival thickness of the central incisors was the largest among the maxillary anterior teeth with statistically significant difference (P<0.05). No correlation was found between the SOG and gingival thickness among the maxillary anterior teeth (P>0.05). Conclusion: The gingival thickness of central incisors was the largest and the supraosseous gingival height had no correlation with gingival thickness among the periodontally healthy maxillary anterior teeth.

Objective: To compare the effects of different imaging methods on radio-opacity. Digital imaging and traditional film imaging were used to determine the radio-opacity of dental composite resin materials. Methods: Fourteen dental composite resins commonly used in clinic were prepared for disc samples with thickness of 1 mm and diameter of 15 mm respectively. The aluminum step wedge was used as the reference and the disc samples were irradiated with X-rays by the traditional film imaging, phosphor imaging plate and charge-coupled device(CCD) intra-oral X-ray sensor respectively. Exposure was set at 65 kV and 7 mA, with 300 mm focus to film distance and the exposure time was 0.25 s. After developing and fixing the film, the optical density of the image of the sample and that of each step of the aluminum step wedge were measured using the densitometer. The digital image file was exported to grey scale analysis software of Adobe Photoshop^® to measure the average grey value in the sample image and aluminum step wedge image. The curves were drawn corresponding to the optical density/gray value of each step of the aluminum step wedge and its thickness, and the equivalent thickness of the aluminum plate was calculated according to the optical density/gray value of the actual measured thickness of the sample, so as to evaluate the radio-opacity of dental composite resin material. Results: For the same sample, the aluminum equivalent measured by traditional film imaging and two other digital imagings had significant differences among the 14 composite resins (P<0.05), and the aluminum equivalent measured by the two digital imagings were greater than that of the traditional film. Moreover the aluminum equivalent measured by the two digital imagings was also different, and the aluminum equivalent measured by the CCD intra-oral X-ray sensor in most composite resins was larger than that measured by phosphor imaging plate. The same sample was photographed with the same imaging method, and the aluminum equivalent was different after three exposures. The standard deviation of aluminum equivalent measured by phosphor imaging plate was the largest, while that measured by CCD intra-oral X-ray sensor was the smallest. Among the 14 dental composite resin materials, the aluminum equivalent of Tetric N-Ceram and Te-Econom Plus measured by traditional film imaging and phosphor imaging plate was significantly higher than other composite resins. Conclusion: Based on clinical significance, three kinds of sensors designed to measure the radio-opacity of dental composite resin, the value of aluminum equivalent will change according to different types of sensors. The aluminum equivalent measured by CCD intra-oral X-ray sensor was higher than that measured by phosphor imaging plate, and the aluminum equivalent measured by phosphor imaging plate was higher than that measured by traditional film imaging. Moreover, even though the same sensor was used, the aluminum equivalent measured by multiple exposures was different. The standard deviation of the aluminum equivalent measured by phosphor imaging plate was greater than that measured by traditional film imaging and CCD intra-oral X-ray sensor. The three sensors in this study could be used for evaluating the radio-opacity of dental composite resin materials. But no matter what kind of sensor was used to measure the radio-opacity of dental composite resin, it complied to ISO 4049: 2019 standard, the materials were suitable for clinical use.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a kind of inherited cardio-myopathy, which is characterized by fibro-fatty replacement of right ventricular myocardium, leading to ventricular arrhythmia. However, rapid atrial arrhythmias are also common, including atrial fibrillation, atrial flutter and atrial tachycardia. Long term rapid atrial arrhythmia can lead to further deterioration of cardiac function. This case is a 51-year-old male. He was admitted to Department of Cardiology, Peking University Third Hospital with palpitation and fatigue after exercise. Electrocardiogram showed incessant atrial tachycardia. Echocardiography revealed dilation of all his four chambers, especially the right ventricle, with the left ventricular ejection fraction of 40% and the right ventricular hypokinesis. Cardiac magnetic resonance imaging found that the right ventricle was significantly enlarged, and the right ventricular aneurysm had formed; the right ventricular ejection fraction was as low as 8%, and the left ventricular ejection fraction was 35%. The patients met the diagnostic criteria of ARVC, and both left and right ventricles were involved. His physical activities were restricted, and metoprolol, digoxin, spironolactone and ramipril were given. Rivaroxaban was also given because atrial tachycardia could cause left atrial thrombosis and embolism. His atrial tachycardia converted spontaneously to normal sinus rhythm after these treatments. Since the patient had severe right ventricular dysfunction, frequent premature ventricular beats and non-sustained ventricular tachycardia on Holter monitoring, indicating a high risk of sudden death, implantable cardioverter defibrillator (ICD) was implanted. After discharge from hospital, physical activity restriction and the above medicines were continued. As rapid atrial arrhythmia could lead to inappropriate ICD shocks, amiodarone was added to prevent the recurrence of atrial tachycardia, and also control ventricular arrhythmia. After 6 months, echocardiography was repeated and showed that the left ventricle diameter was reduced significantly, and the left ventricular ejection fraction increased to 60%, while the size of right ventricle and right atrium decreased slightly. According to the clinical manifestations and outcomes, he was diagnosed with ARVC associated with arrhythmia induced cardiomyopathy. According to the results of his cardiac magnetic resonance imaging, the patient had left ventricular involvement caused by ARVC, and the persistent atrial tachycardia led to left ventricular systolic dysfunction.

To investigate the surgical effect of hip arthroscopic labrum reconstruction. A retrospective study was performed on the clinical data of 12 patients who underwent hip arthroscopic labrum reconstruction in our department from September 2017 to February 2021 and were followed up for 5-46 months, with an average of 21.5 months. All the patients had a hip joint space of more than 2 mm, and Tonnis grade less than level Ⅱ. These 12 patients underwent arthroscopic debridement of hyperplastic synovium, femoral head and neck and/or acetabular osteoplasty, and labrum reconstruction using autograft iliotibial band or gracilis tendon. After the surgery, we conducted follow-up and data collection, recorded the satisfaction of the patients and occurrence of complications, as well as the cartilage lesion of hip joint observed under the arthroscopy. We compared the alpha angle of Dunn X-ray film, center-edge angle (CE angle) of AP X-ray film, modified Harris hip score (mHHS score), hip outcome score (HOS), international hip outcome tool 12 score (iHOT12 Score), and visual analogue scale (VAS scale) before and after the arthroscopic operation, to assess clinical symptom relief and joint function recovery. The 12 patients were followed up for 5-46 (21.5±12.8) months. The VAS scale were (5.3±2.5) and (2.5±1.4) before and after the surgery, showing significant decrease (P=0.018). The mHHS score were (60.6±22.2) and (83.1±5.8) before and after the surgery, showing significant increase (P=0.003). The patient satisfaction was high (7.8±2.0) (range: 0-10). None of the 12 patients had serious complications, revision surgery, or total hip replacement at the end of the last follow-up. Autologous tendon transplantation for reconstruction of acetabular labrum under arthroscopy can improve the clinical symptoms and joint function of patients with femoroacetabular impingement (FAI), which is a safe and effective treatment.