Cartilage degeneration stands as the main pathological hallmark of joint diseases such as osteoarthritis(OA),characterized by the degradation of cartilage matrix,abnormal cell function,and disruption of structural integrity.This series of changes poses a severe threat to patients' quality of life.The significant impact of mechanical stimuli on cartilage health and function has long been widely acknowledged,and research on its underlying mechanisms has become relatively systematic and in-depth.However,the specific pathways in which mechanical stimuli affect cartilage,as well as the hidden laws and intrinsic mechanisms behind them,are still in the process of continuous exploration,gradual revelation,and ongoing refinement.This article reviews the research progress in the field of mechanical stimuli and articular cartilage in 2024,indicating that it demonstrated characteristics of greater diversity in research subjects,broader perspectives,and more innovative techniques,further expanding our understanding of the role of mechanical factors in cartilage degeneration.The mechanical regulation-based therapeutic strategies are also explored,such as exercise therapy,biomechanical correction,chemical drug therapy,acupotomy therapy,and tissue engineering,providing theoretical foundations and practical directions for the prevention and treatment of degenerative joint diseases.Future research should concentrate on the integration of multi-scale and multi-perspective mechanisms as well as clinical translation to promote the application of precision medicine in the field of cartilage degeneration.

Objectives:To compare the biomechanical characteristics of 3D-printed titanium alloy artificial vertebral bodies(AVB)with standard,self-stabilizing,and truss structures in spinal reconstruction after total en bloc spondylectomy(TES).Methods:A finite element model of the normal spine was constructed based on the CT data of the T10-L2 segments of a healthy adult male and was subsequently validated.The defect after vertebral column resection was simulated by removing the T12 vertebra,and three types of 3D-printed titanium alloy AVBs were implanted:standard(cylindrical),self-stabilizing(with two pairs of screws at the upper and lower ends),and truss(with bilateral ring holes for screw-rod connection).A 200N axial load and a 7.5N·m torque were applied using Abaqus software to simulate flexion,extension,lateral bending,and rotation movements.The overall stiffness of the"vertebra-prosthesis-vertebra"composite structure,the stress distributions on the posterior column connecting rod,the endplate,and the fusion device were analyzed.Results:The range of motion of the T10-L2 normal spinal finite element model established in this study was consistent with previous literature reports,therefore validating the model.Stiffness analysis showed that the displacement difference among the standard,truss,and self-stabilizing AVBs under the same load was 0.1mm,with the self-stabilizing structure AVB exhibiting the smallest displacement;The truss structure had smaller displacement in left-right bending.Stress analysis results indicated that the posterior column connecting rods of the three kinds of morphological AVBs bore the maximum Von Mises stress(174.90-175.00MPa)during rotation.Compared with the standard structure,the truss structure reduced the mid-segment stress of the posterior column connecting rod by 18.5％-24.3％during flexion-extension and lateral bending.Endplate stress analysis revealed that the maximum Von Mises stress on the endplate occurred during flexion,with values of 32.54MPa,30.76MPa,and 24.37MPa for the standard,truss,and self-stabilizing structures,respectively.The self-stabilizing structure reduced endplate stress by 14％-30％compared with the other two structures.Analysis of the internal fixation system showed that the cage stress of the self-stabilizing AVB was significantly lower than that of the standard and truss structures:reduced by 57％and 61％in flexion;52％-62％and 59％-64％in lateral bending;and 61％-62％and 46％-61％in rotation,respectively.Conclusions:Compared to the standard structure,the truss structure AVB reduces the stress concentration of the posterior column connecting rod through a multi-segment stress dispersion mechanism.The self-stabilizing structure AVB enhances the stability of the prosthesis-vertebral body interface through screw fixation.

Objectives:To investigate the risk factors and treatment methods for distal junctional isthmic spondylolisthesis(DJIS)following posterior lumbar decompression and fixation surgery.Methods:The 10 patients who were treated at our hospital for DJIS following posterior decompression and fixation between January 2015 and January 2022 were retrospectively analyzed.The patients were included in the DJIS group,including 7 males and 3 females,aged 63.4±10.3(45-75)years old.And according to age,gender,preoperative diagnosis,operative stage,and operative method,the patients were matched in a ratio of 1∶2 with some other patients who didn't develop DJIS after underwent posterior decompression and fixation at our hospital due to lumbar degenerative diseases during the same period as control(20 cases).The general data[body mass index(BMI),L1 CT value,proportion of patients with osteoporosis)],laminectomy range of the lower vertebra(transverse decompression percentage of lamina,spinous process resection percentage),pelvic incidence(PI),and postoperative lumbar lordosis(LL),pelvic tilt(PT),sacral slope(SS),etc.of the two groups were compared to explore the risk factors for DJIS after posterior lumbar decompression and fixation.The treatment methods for DJIS were also summarized.Results:The BMI of patients in the DJIS group was significantly higher than that of the control group(27.4±4.1kg/m2 vs.23.7±3.4kg/m2,P＜0.001).The L1 vertebral CT value of the DJIS group was significantly lower than that of the control group(105.2±43.9HU vs.133.5±23.5HU,P=0.028),and the proportion of patients with osteoporosis of the DJIS group was higher(70％vs.10％,P=0.003).The DJIS group was greater in PI(52.5°±8.8° vs.45.8°±7.4°,P＜0.05)and postoperative LL(47.4°±14.3° vs.36.5°±10.6°,P＜0.05)significantly than the control group,PT and SS were not significantly different between the two groups(P＞0.05).Additionally,the transverse decompression percentage of lamina of the lower vertebra[(89.3±9.0)％vs.(78.0±3.2)％,P＜0.05]and the spinous process resection percentage of the distal vertebra[(51.1±16.1)％vs.(39.3±9.1)％,P＜0.05]in the DJIS group were also significantly higher than those in the control group.Eight DJIS patients underwent distal decompression,reduction,fixation,and fusion surgery,and their quality of life scores significantly improved after revision surgery.Two DJIS cases with mild clinical manifestations were treated conservatively,no symptom exacerbation was reported during follow-up.Conclusions:High BMI,osteoporosis,high PI,and excessive distal vertebral lamina resection during surgery are potential risk factors for DJIS after posterior lumbar decompression and fixation.

Osteoarthritis is a common joint disease characterized by progressive degeneration of articular cartilage, leading to pain and dysfunction. Mesenchymal stem cells (MSCs) have emerged as a promising tool for the treatment of osteoarthritis due to their ability to attenuate inflammatory responses, promoting cartilage repair, and immunomodulation. Recent studies have further clarified the mechanism of MSCs in treating osteoarthritis, including direct differentiation into chondrocytes, secretion of anti-inflammatory factors, and regulation of immune response, etc. Meanwhile, researchers are conducting phase I or phase II clinical trials of MSCs in treating osteoarthritis, and positive results have been achieved. Bone marrow-derived MSCs have strong potential for multidirectional differentiation and can effectively alleviate inflammation and promote cartilage repair, but their proliferative and immunomodulatory capacities are relatively low; adipose-derived MSCs show strong anti-inflammatory effects but are slightly less efficient in cartilage regeneration; umbilical cord-derived MSCs show great potential for cartilage repair and immunomodulation and synovial-derived MSCs have excellent chondrogenesis and immunomodulation. MSCs from synovial membrane have excellent chondrogenic capacity but are difficult to obtain. Despite the current promising research results on MSCs for osteoarthritis, clinical issues such as the choice of MSC source, mode of administration, and long-term safety and efficacy still need to be further explored.

Objective:To investigate the effects of thoracolumbar vertebral fracture with incomplete spinal cord injury on male sexual function and postoperative prognosis.Methods:A retrospective review was conducted on data from 144 male patients with thoracolumbar vertebral fractures and incomplete spinal cord injuries treated between May 2009 and May 2021 in the Department of Traumatology and Orthopedics at Peking University Third Hospital. Patients ranged in age from 19 to 55 years (mean: 38.6±10.6 years) and underwent posterior incision and reduction internal fixation. The International Index of Erectile Function-5 (IIEF-5), the Premature Ejaculation Diagnostic Tool (PEDT), and the International Spinal Cord Injury Male Sexual Function Basic Data Set were used for sexual function evaluation. Based on the American Spinal Injury Association (ASIA) Spinal Cord Injury classification, changes in neurological and sexual function were assessed at the pre-injury stage, 3 months post-injury, 2 years postoperatively, and at the final follow-up. Factors influencing sexual dysfunction and recovery were analyzed. Spearman correlation analysis was used to identify factors affecting sexual function injury and recovery.Results:A total of 117 patients were included in the final analysis. Follow-up duration ranged from 26.2 to 161.7 months (mean: 74.6±40.5 months). After injury, ASIA grades were distributed as follows: 43 patients with grade B, 41 with grade C, and 33 with grade D. At the 2-year follow-up, 30 patients were grade E, 63 grade D, 19 grade C, and 5 grade B. Improvement in ASIA classification was observed in 90.6% (106/117) of patients: 79 improved by one grade, 27 by two grades, 8 remained unchanged, 1 worsened by one grade, and 2 worsened by two grades. Mean IIEF-5 scores were 19.5±6.4 pre-injury, 8.7±8.0 at 3 months post-injury, and 17.5±7.1 at 2 years postoperatively, with statistically significant differences ( F=123.247, P<0.001). Differences between 3 months post-injury vs. pre-injury and 2 years postoperatively vs. 3 months post-injury were statistically significant ( P<0.05). Mean PEDT scores were 5.3±3.1 pre-injury, 6.9±5.2 at 3 months post-injury, and 6.4±5.1 at 2 years postoperatively, with statistically significant differences ( F=17.014, P<0.001). The difference between 3 months post-injury and pre-injury was statistically significant ( P<0.05), but not between 2 years postoperatively and 3 months post-injury ( P>0.05). At the 2-year follow-up, 96 patients had their IIEF-5 classification restored to pre-injury levels, 85 restored PEDT classifications, and 83 restored both. Post-injury ASIA classification was positively correlated with a decrease in IIEF-5 score and an increase in PEDT score at 3 months post-injury ( P<0.05). Injury segment was positively correlated with the decrease in IIEF-5 score ( P<0.05). Time from injury to surgery showed a positive correlation with increased PEDT score at 3 months ( P<0.05). Post-injury ASIA grade, injury segment, time to surgery, age, intraoperative decompression, and spinal cord function recovery all showed significant correlations with changes in IIEF-5 and (or) PEDT scores at 2 years postoperatively ( P<0.05). According to the International Spinal Cord Injury Male Sexual Function Basic Data Set, the proportion of patients willing to discuss sexual issues increased from 29.9% at 3 months post-injury to 47.9% at 2 years postoperatively ( P<0.05). The proportion of patients with absent or diminished psychogenic erections remained stable (48.7% vs. 48.9%, P>0.05), while those with normal reflexive erections increased from 34.2% to 65.0% ( P<0.05). Conclusion:Thoracolumbar fractures with incomplete spinal cord injury result in reduced erectile function and increased incidence of premature ejaculation. The degree of spinal cord injury and the level of the injured segment are strongly correlated with the extent of sexual dysfunction. At the 2-year postoperative follow-up, 70.9% of patients had recovered sexual function to pre-injury levels.

Objective:To investigate the effect of robot-assisted total knee arthroplasty (TKA) on the incidence of postoperative deep vein thrombosis (DVT) in the lower limbs.Methods:A total of 405 patients who underwent primary unilateral TKA in the Department of Orthopaedics, Peking University Third Hospital from June 2022 to June 2024 were retrospectively analyzed, consisting of 89 males and 316 females, with a mean age of 67.84±5.60 years. Patients were divided into the conventional group ( n=215) and the robot-assisted group ( n=190) according to the surgical approach. Postoperative DVT incidence, operative time, postoperative hemoglobin and hematocrit levels, perioperative blood loss, and transfusion rate were compared between the two groups to evaluate the impact of robot-assisted TKA on thrombotic events and related clinical indicators. Results:There were no significant differences in age, sex, height, weight, body mass index, or preoperative laboratory results including hemoglobin and hematocrit levels between the two groups ( P>0.05). The postoperative DVT incidence was 26.8% (51/190) in the robot-assisted group and 34.9% (75/215) in the conventional group, with no significant difference ( P>0.05). Univariate logistic regression analysis showed that sex ( P=0.013) and age ( P=0.024) were significantly associated with DVT occurrence. Multivariate logistic regression further revealed that female patients had a significantly higher incidence of DVT than males ( OR=0.438, P=0.005), and older patients had a significantly increased risk of DVT ( OR=1.046, P=0.025); body mass index remained not significantly associated with DVT ( P=0.092). The operative time in the robot-assisted group was 88.62±18.58 min, which was significantly longer than that in the conventional group 79.23±17.68 min ( t=-5.207, P<0.001). Perioperative total blood loss was 1 079.85±344.18 ml in the robot-assisted group and 1 141.47±363.70 ml in the conventional group, with no significant difference ( t=1.745, P=0.082). The transfusion rate was 5.3% in the robot-assisted group and 5.1% in the conventional group, respectively, with no significant differences (χ 2=0.004, P=0.947). Conclusion:Compared with conventional TKA, robot-assisted TKA results in longer operative time but does not increase perioperative blood loss or the risk of postoperative DVT.

Objective:To compare the anterior long-segment fixation, posterior long-segment fixation, and combined anterior-posterior fixation in the treatment of ankylosing spondylitis with cervical fracture (ASCF).Methods:A retrospective study was conducted to analyze the 153 patients with ASCF who had been treated at Department of Orthopaedics, Peking University Third Hospital and Department of Orthopedics, Luoche Central Hospital between January 2014 and December 2023. The cohort included 86 males and 67 females, with an age of (41.6±11.5) years, a disease duration of (10.0±3.9) years, and an interval from injury to surgery of (3.3±1.4) d. By Frankel's classification for preoperative nerve injury, 57 cases were grade B, 51 grade C, and 45 grade D. Based on the surgical approaches, the patients were divided into 3 groups: an anterior group ( n=63) undergoing the anterior cervical long-segment fixation, a posterior group ( n=51) undergoing the posterior cervical long-segment fixation, and a combination group ( n=39) undergoing combined anterior-posterior cervical fixation. Surgical time, intraoperative blood loss, fracture healing, complications, and changes in Frankel grading for spinal cord injury were compared among the 3 groups. Results:There was no statistically significant difference in the preoperative general data among the 3 groups, indicating comparability ( P > 0.05). All patients were followed up for (33.5±12.0) months after surgery. In the anterior group, the surgical time [(103.0±16.8) min] was significantly shorter than that in the posterior group [(148.4±17.7) min] and that in the combination group [(228.5±23.9) min], the intraoperative blood loss [(92.8±27.8) mL] was significantly less than that in the posterior group [(477.5±109.5) mL] and that in the combination group [(769.5±136.9) mL], and the incidence of complications [9.5% (6/63)] was significantly lower than that in the posterior group [41.2% (21/51)] and that in the combination group [53.8% (21/39)] (all P<0.05). There was no statistically significant difference in the fracture healing time among the 3 groups ( P=0.111). At the last follow-up, X-ray and CT scans showed no loosening or breakage of internal fixation in all the 3 groups. The Frankel grading at the last follow-up: 12 cases of grade C, 15 cases of grade D, and 36 cases of grade E in the anterior group; 3 cases of grade B, 12 cases of grade C, 12 cases of grade D, and 24 cases of grade E in the posterior group; 6 cases of grade C, 12 cases of grade D, and 21 cases of grade E in the combination group. At the last follow-up, all patients showed a significant improvement compared to their Frankel grades before surgery ( P<0.001), but there was no statistically significant difference between the 3 groups ( H=2.238, P=0.327). Conclusions:In the treatment of ASCF, anterior long-segment fixation is advantageous over posterior long-segment fixation and combined anteri-or-posterior fixation due to its shorter surgical time, reduced intraoperative blood loss, and a lower complication incidence. All the 3 surgical approaches demonstrate comparable outcomes in terms of fracture healing time, radiographic stability, and final neurological recovery.

Craniocervical junction zone malformations often have an insidious onset, a variety of clinical phenotypes, and are often combined with multiple malformations, making their systematic classification and staging more difficult.At present, craniocervical junction area malformations are often classified into congenital and acquired, and can also be classified into skull base malformations, atlantoaxial malformations, and cardinal malformations according to their locations. For patients with obvious occipitocervical or atlantoaxial instability, combined with symptoms of high cervical spinal cord damage, internal fixation and fusion surgery should be performed aggressively to avoid irreversible nerve damage.There is a lack of detailed categorisation and summary of the treatment of diseases associated with craniocervical junction malformations in the literature, and the treatment strategies for some of these malformations are still controversial, with different perceptions and treatment concepts in the national and international literature.

Objective:To explore the application effects of a four-in-one blended teaching model integrating artificial intelligence, virtual reality, 3D printing, and case-based learning (CBL) in the clinical teaching of spinal tumors.Methods:We divided 89 students on training in the Department of Orthopedics of Peking University Third Hospital from September 2022 to August 2024 into control group ( n=47) and experimental group ( n=42). The control group adopted traditional teaching, and the experimental group adopted the four-in-one teaching model. At the end of clinical teaching, an artificial intelligence test and a questionnaire survey were administered to the students to evaluate the teaching effects. The two groups were compared using the independent samples t-test with the use of SPSS 27.0. Results:The experimental group was superior to the control group with significant improvements in the answer accuracy rate (66.67%, χ2=9.44, P=0.002), learning interest [(4.50±0.63), t=2.75, P=0.007], theoretical knowledge mastery [(4.64±0.69), t=7.74, P<0.001], clinical thinking [(4.48±0.71), t=9.08, P<0.001], practical skills [(4.13±0.89), t=2.69, P=0.009], scientific research innovation [(4.71±0.59), t=9.28, P<0.001], teacher-student interaction [(4.74±0.54), t=12.76, P<0.001], and classroom attention [(4.69±0.52), t=12.64, P<0.001]. At the same time, the students in the experimental group put forward numerous constructive feedback. Conclusions:The four-in-one blended teaching model combining artificial intelligence, virtual reality, 3D printing, and CBL can help undergraduate medical students better recognize and diagnose spinal tumors with a correct clinical thinking path, achieving good teaching effects.

Osteoarthritis is a common joint disease characterized by progressive degeneration of articular cartilage, leading to pain and dysfunction. Mesenchymal stem cells (MSCs) have emerged as a promising tool for the treatment of osteoarthritis due to their ability to attenuate inflammatory responses, promoting cartilage repair, and immunomodulation. Recent studies have further clarified the mechanism of MSCs in treating osteoarthritis, including direct differentiation into chondrocytes, secretion of anti-inflammatory factors, and regulation of immune response, etc. Meanwhile, researchers are conducting phase I or phase II clinical trials of MSCs in treating osteoarthritis, and positive results have been achieved. Bone marrow-derived MSCs have strong potential for multidirectional differentiation and can effectively alleviate inflammation and promote cartilage repair, but their proliferative and immunomodulatory capacities are relatively low; adipose-derived MSCs show strong anti-inflammatory effects but are slightly less efficient in cartilage regeneration; umbilical cord-derived MSCs show great potential for cartilage repair and immunomodulation and synovial-derived MSCs have excellent chondrogenesis and immunomodulation. MSCs from synovial membrane have excellent chondrogenic capacity but are difficult to obtain. Despite the current promising research results on MSCs for osteoarthritis, clinical issues such as the choice of MSC source, mode of administration, and long-term safety and efficacy still need to be further explored.