To develop total knee arthroplasty models with different femoral prosthesis flexion angles， and to investigate the effects of femoral prosthesis placement at abnormal sagittal angles on the biomechanical characteristics of the artificial knee joint by means of finite element analysis.
Methods
The finite element analysis method was used to establish the artificial knee joint models of femoral prosthesis extension，neutral，mild flexion，and hyperflexion，respectively.Subsequently，the working conditions under upright and flexed knee positions were simulated，and the peak von-Mises stress was used as an observation index to statically analyze the trend of contact pressure changes in the tibiofemoral and patellofemoral joints of the artificial knee under different femoral prosthesis flexion angles.
Results
（1）The peak von-Mises stress of the femoral prosthesis in the upright position gradually increased with the increase of the femoral prosthesis flexion angle， from 4.523 MPa to 7.148 MPa， and the stress was concentrated in the circular-like region of contact between the femoral prosthesis and polyethyleneliner，which shifted forward with the deepening of the prosthesis flexion；the peak von-Mises stress on the upper surface of the polyethylene liner also increased with the degree of prosthesis flexion，reaching a maximum of 13.622 MPa when the prosthesis was hyperflexed， which was located at the anterior end of the liner column， and the trend of the stressconcentration area was consistent with that of the femoral prosthesis. （2） When the knee was flexed at 30°， the stress was mainly concentrated on the medial patellofemoral joint surface； as the knee flexion angle increases to 60°，the stress concentration area shifted upward，and the stress on the medial and lateral patellofemoral joint surface were then increased.Under the same knee flexion angle，the peak von-Mises stress of the patellar cartilage in the prosthesis flexion group was higher than that of the prosthesis neutral group，and it was gradually increasing with the increase of the femoral prosthesis flexion angle， but both of them were smaller than that in the prosthesis extension group.
Conclusions
The sagittal placement angle of femoral prosthesis is an important factor affecting the biomechanics of the artificial knee joint.In the posterior-stabilizedtotal knee arthroplasty model，both prosthesis hyperflexion and extension resulted in elevated patellofemoral joint contact pressures，whereas the peak stress on the upper surface of the liner was more affected by prosthesis hyperflexion. In clinical practice， when a mismatch between the prosthesis model and the patient's joint dimensions is encountered， placement of the femoral prosthesis in a mildly flexed position may be considered， but hyperflexion and extension of the prosthesis should be avoided.
To explore the role of lower extremity biomechanical evaluation in foot and ankle disease.
Methods
360 patients suspected of foot and ankle disease in Hengshui Second People's Hospital were analyzed retrospectively.All patients were classified according to suspected disease types： Group A（ankle fracture patients）， group B （Lisfranc injury patients）， group C （flat foot patients）， group D （bunion valva patients）；Each group was randomly divided into control group and observation groups according to the random number table method. The patients in control group were diagnosed and treated according to traditional imaging evaluation； In the observation group， lower extremity biomechanical assessment was added along with imaging evaluation to make diagnosis and treatment plan，and the differences of diagnosis results between the two groups were recorded. Follow-up visits at 3 months and 12 months after the end of treatment were conducted to evaluate the improvement using the AOFAS（American Orthopaedic Foot and Ankle Society） median foot score and VAS （Visual Analogue Scales） scores. The therapeutic effects of the control group and the observation group were statistically analyzed.
Results
Among 81 patients suspected of ankle fracture in each group of GroupA，the diagnostic accuracy of the observation group was 92.59%，higher than that of the control group（77.78%）.The rates of misdiagnosis and missed diagnosis were 28.57%and 5.41%，lower than those of the control group （46.15% and 17.65%）， the difference was statistically significant （P＜0.05）.Among 35 patients with suspected Lisfranc injury in each group of Group B，the diagnostic accuracy of the observation group was 94.29%，higher than that of the control group（62.86%）.The rates of misdiagnosis and missed diagnosis were 12.50% and 3.70%， lower than those of the control group （70.00% and 24.00%），the difference was statistically significant（P＜0.05）.Among 42 patients suspected of flatfoot in each group of GroupC，the diagnostic accuracy of the observation group was 95.24%，higher than that of the control group（71.43%）.The rates of misdiagnosis and missed diagnosis were 10.00% and 3.13%， lower than those of the control group （50.00% and 20.00%）， the difference was statistically significant （P＜0.05）. Similarly，Among 22 suspected bunion valgus patients in each group of GroupD， the diagnostic accuracy of observation group was 90.91%，higher than that of control group（59.09%）.The rates of misdiagnosis and missed diagnosis were 0.00%and 11.11%，lower than those of the control group（80.00%and 29.41%），the difference was statistically significant （P＜0.05）. Correlation analysis showed that AOFAS and VAS scores were the most correlated with the peak pressure of medial foot （r=0.787，-0.740， P=0.012， 0.033） among ankle fracture patients. The correlation between AOFAS score and average walking speed was the strongest （r=0.711， P=0.015）， and the correlation between VAS score and peak pressure of medial foot was the strongest（r=-0.707，P=0.013）in Lisfranc injury patients.The correlation between AOFAS score and self-selected step speed was the strongest（r=0.597，P=0.035），the correlation between VAS score and the peak pressure of the first metatarsal bone was the strongest（r=-0.550，P=0.041）in patients with flat feet.In bunion valgus patients，the correlation between AOFAS score and the peak pressure of the first metatarsal bone was the strongest（r=0.641，P=0.027），and the correlation between VAS score and the peak pressure of the medial foot was the strongest （r=-0.623， P=0.042）.
Conclusions
The addition of biomechanical evaluation on the basis of traditional X-ray diagnosis could significantly improve the accuracy of some diagnosis of foot and ankle diseases.A part of the mechanical evaluation indexes had strong correlation with the clinical scores of patients，and might have guiding significance for the treatment of foot and ankle diseases，as well as postoperative rehabilitation.
To explore the outcomes of surgery and prognostic factors on survival in patients with spinal metastases secondary to renal carcinoma.
Methods
A retrospective analysis was performed on 16 patients with renal carcinoma spinal metastases who were undergone surgeries at Tianjin Hospital from December 2019 to March 2023. Clinical data， KPS score， NRS score， Frankel grade， postoperative treatment measures， local recurrence rate and survival status of the patients were collected. The median survival time and postoperative survival rates were estimated by Kaplan-Meier method.A systematic review was conducted by searching the PubMed， Embase， and Cochrane Library databases. The related clinical studies on surgical treatment of spinal metastases from renal carcinoma were collected from 1964 to October 12，2023.After evaluating the quality of the literatures，a descriptive analysis was performed.
Results
A total of 16 patients were included in the retrospective analysis，all of whom were male，with an average age of 62.0±9.5 years.Among all the patients， 5 underwent en bloc spondylectomy （TES） （31.25%）， 9 underwent piecemeal resection（56.25%），and 2 underwent percutaneous vertebroplasty（PVP）（12.5%）.Preoperative embolization was performed in 3 among the 14 patients who underwent open surgery（21.43%），and the mean intraoperative blood loss was 1 707.19±1 512.14 ml. The preoperative KPS score was 51.87±20.40 and significantly increased to 64.38±27.80 postoperatively（P=0.052）.The preoperative NRS score was 6.2±1.4 and decreased to 2.5±2.0 postoperatively （P＜0.001）.There were 2 patients of Frankel Grade A， 1 patient of Grade C， 7 patients of Grade D and 6 patients of Grade E before surgery. Postoperatively， there were 3 patients of Grade A，1 patient of Grade B，3 patients of Grade D and 9 patients of Grade E，but without statistically significant difference （P=0.792）. The median follow-up time was 23 months， with 8 deaths by the last followup. The median survival time was 26.0 months （95% CI： 3.0， 20.1）， The overall survival rates at 1y， 2y and 3y were 88%、63 and 31% respectively.After screening， 15 studies were included in this systematic review involving a total of 1007 patients.Six studies found that surgery effectively relieved pain in patients with renal carcinoma spinal metastases， while seven studies demonstrated that surgery improved neurological function in patients with metastatic epidural spinal cord compression （MESCC）. However， the conclusions on whether different surgical types could bring survival benefit and whether preoperative embolization could reduce intraoperative blood loss were conflicted. The postoperative median overall survival ranged from 6 to 34.7 months.Multiple studies confirmed that visceral and multiple bone metastases were negative prognostic factors affecting the survival of patients with renal carcinoma spinal metastases.
Conclusions
Surgery can effectively alleviate pain and facilitate the recovery of spinal cord function for the patients with renal carcinoma spinal metastases.The main negative prognostic factors affecting the overall survival are the presence of visceral metastasis and multiple bone metastases.
To explore the endoscopic revision and surgical techniques for middle-aged or elderly people with L5/S1 recurrent lumbar disc herniation（rLDH）after percutaneous endoscopic interlaminar discectomy （PEID）.
Methods
From May 2018 to October 2022， 52 middle-aged or elderly patients who underwent percutaneous endoscopic lumbar discectomy for L5/S1 rLDH after PEID were enrolled in the present study，including 28 males and 24 females with a mean age of 58.154±10.634 years.Based on strategy of the endoscopic revision， patients were divided into PETD group （n=22） and PEID group （n=30），and their demographic data and surgery-related indicators were compared. The visual analogue scale （VAS） for back and leg pain， oswestry disability index （ODI） and Japanese Orthopaedic Association Score （JOA） were recorded to evaluate the clinical outcomes.
Results
No significant differences were found in the demographic data， operative time， and intraoperative blood loss between the two groups （P＞0.05）， but the time of intraoperative X-ray fluoroscopy exposures in the PEID group were significantly shorter than that in the PETD group（P＜0.05）.The follow-up data of the two groups were analyzed by repeated-measures ANOVA，which showed no statistically significant differences between the groups（P＞0.05），statistically significant differences between the different time points （P＜0.05）， and no interaction between the groups and the time points （P＞0.05）. No serious complication observed during the follow-up.
Conclusions
For recurrent LDH after PEID of L5/S1 segments， percutaneous endoscopic revision can achieve satisfactory results. And since the time of intraoperative X-ray fluoroscopy exposures in the PEID group are shorter， the PEID technique is considered as the preferred revision technique when both procedures can remove the compressive material well.And for several specific types of recurrence，mastering the application of the two procedures can effectively minimize the difficulty of the surgery.
To evaluate the value of low-dose CT volume scanning combined with 3 D reconstruction in the classification of intertrochanteric fractures.
Methods
Selected 107 patients with intertrochanteric fractures from March 2023 to March 2024， all patients underwent low-dose CT volume scan combined with three-dimensional reconstruction and X-ray plain ray examination， to compare the difference between low-dose CT volume scan， X-ray plain ray exploration and the number of fracture blocks.
Results
The overall accuracy of 87.85%was 84.38%，88.46%，88%，88.24%，10.38%，100.00%，and the Kappa value was 0.867 （P＜0.05）.The overall accuracy of intertrochanteric fracture classification by X-ray diagnosis was 78.50%， for type Ⅰand each stage to type Ⅱ， the accuracy was 75.00%， 76.92%， 80.00%， 82.35% and 85.71%， respectively. The Kappa value was 0.753， significant （P＜0.05）. Although the number of fracture blocks identified by low-dose CT volume scanning combined with 3 D reconstruction was less than that found by surgical exploration，the difference was not statistically significant（P＞0.05）；the number of fracture blocks detected by X-ray plain film was significantly lower than the number of surgical exploration （P＜0.05）.
Conclusion
Low-dose CT volume scanning combined with three-dimensional reconstruction in intertrochanteric fracture classification showed high accuracy and reliability， can be used as a valid diagnostic tool for fracture classification，although in the number of fracture block detection and surgical exploration differences，but the difference is not significant，and does not affect its value in clinical application.
To evaluate the therapeutic value of modified Henry approach for the treatment of distal radius fractures and to analyze the long-term prognosis of patients.
Methods
A total of 100 patients with distal radius fracture admitted to our hospital from February 2021 to February 2023 were retrospectively selected and divided into control group and improved group with 50 cases in each group according to different surgical methods.The control group underwent conventional Henry approach internal fixation， and the improved group underwent modified Henry approach to preserve anterior rotation intramural fixation.The clinical effect，operation time，blood loss and fracture exposure time of the two groups were compared.Serum malondialdehyde（MDA），superoxide dismutase（SOD）and C-reactive protein（CRP）levels were detected before surgery and 3 months after surgery.Visual analogue pain scale（VAS）and Cooney wrist joint score were performed before surgery and 3 and 6 months after surgery.Wrist flexion，dorsal extension and forearm rotation were compared between the two groups before surgery and 6 and 12 months after surgery.Radius height was recorded 1d and 12 months after surgery，radius loss height was calculated，and complications were analyzed.
Results
100 patients were successfully followed up for 12 months. The excellent and good rate of the improved group（96.00%）was higher than that of the control group（82.00%）（P＜0.05）.The blood loss in the improved group was lower than that in the control group，and the operation time and fracture exposure time were shorter than that in the control group（P＜0.05）.The levels of MDA and CRP were lower and the levels of SOD were higher in the two groups 3 months after operation，and MDA and CRP were lower and SOD were higher in the improved group than in the control group （P＜0.05）. VAS score of 3 and 6 months after surgery was lower in 2 groups than before surgery，Cooney score was higher than before surgery，and VAS score of 3 and 6 months after surgery in the improved group was lower than that in the control group，Cooney score was higher than that in the control group（P＜0.05）.Wrist flexion，dorsal extension and forearm rotation were higher in 2 groups 6 and 12 months after surgery than before surgery，and the improved group was higher than the control group（P＜0.05）.The height of radius loss in the improved group was lower than that in the control group（P＜0.05）.There was no difference in complication rate between 2 groups.
Conclusion
The modified Henry approach can improve the short-term efficacy of patients with distal radius fractures，shorten the operation and fracture exposure time，reduce the amount of blood loss，reduce postoperative inflammation and stress response，further improve the long-term wrist range of motion，reduce the height of radius loss，and have high safety.
Rotator cuff injuries are the most common cause of shoulder pain and dysfunction.At present，arthroscopic rotator cuff repair is a popular and well-established technique with satisfactory clinical outcomes，but many variables in postoperative patient rehabilitation programs are not well studied and it is difficult to support rehabilitation therapists to make decisions quickly and reliably. With the gradual attention to rehabilitation and the deepening of research， new breakthroughs have been made in the rehabilitation of arthroscopic rotator cuff repair.This article reviews the influencing factors and rehabilitation techniques of postoperative rehabilitation of arthroscopic rotator cuff injury repair in recent years， in order to provide a basis for clinical decision-making on rotator cuff injury repair and determine the most effective rehabilitation program.
