Bone-anchored prostheses (BAP) provide an alternative to traditional socket-suspended prostheses (SSP) for individuals with transfemoral amputation (TFA) by addressing socket-related complications. While most previous studies, primarily single-arm trials, report positive outcomes with BAP, these findings may be overestimated due to lower preoperative baseline function among individuals using SSP prior to BAP implantation. This review aims to offer a more balanced comparison of functional and clinical outcomes between BAP and SSP by focusing exclusively on two-arm comparative studies. A systematic review and meta-analysis was conducted from December 2024 to May 2025, following PRISMA guidelines. Databases including PUBMED, EMBASE, Scopus, Cochrane, and Web of Science were searched. All studies meeting the inclusion criteria were cross-sectional in design. Primary outcomes included mobility (Timed Up and Go [TUG]; Activities-specific Balance Confidence [ABC]) and quality of life (Q-TFA domains). Secondary outcomes: gait parameters, hip range of motion (ROM), osseoperception, and costs. Risk of bias was assessed using ROBINS-I adapted for observational designs. Random-effects meta-analyses pooled mean differences (MD) or standardized mean differences (SMD) with 95% CIs. Twelve studies (BAP n = 200; SSP n = 244) met criteria. Pooled analyses showed no significant differences for TUG (MD 0.16 s, 95% CI −2.09 to 2.41; I² = 0%), ABC (MD 0.05, 95% CI −22.19 to 22.29; I² = 76.3), Q-TFA Global (MD 1.14, 95% CI −22.02 to 24.30), Q-TFA Prosthetic Mobility (MD 0.37, 95% CI −9.93 to 10.68), Q-TFA Problems (MD –6.29, 95% CI –18.77 to 6.19), Q-TFA Prosthesis Use (MD 1.18, 95% CI −2.36 to 4.71), and gait speed (MD −0.03 m/s, 95% CI −0.31 to 0.25). Hip ROM tended to be higher with BAP in two studies; osseoperception favored BAP in two studies; one study reported on lower long-term cost with BAP. No comparative studies of infection were identified. While BAP is a promising alternative for individuals experiencing complications with SSP, its benefits for functional SSP users remain uncertain. The lack of comparative studies evaluating infection rates highlights an important area for future research.

Background: Spondylolisthesis is a frequently encountered condition in orthopedics, requiring dynamic stability maintained primarily by the paraspinal muscles. This systematic review evaluates the cross-sectional area (CSA) and fat infiltration (FI) of paraspinal muscles—specifically the multifidus, erector spinae, and psoas major—in lumbar spondylolisthesis (LS) to understand their roles in spinal stability and progression in degenerative and isthmic forms.

Methods: Following PRISMA guidelines, PubMed, Cochrane, and Scopus were searched as of September 2024. Fourteen retrospective studies using MRI/CT imaging met inclusion criteria, focusing on CSA and FI in LS. Data were extracted from studies that assessed spinal instability through vertebral slippage measurements or comparisons with asymptomatic controls.

Results: The findings indicate that reduced CSA and increased FI in paraspinal muscles, especially the multifidus, are associated with spinal instability and progressive vertebral slippage. Several studies reported reductions in CSA and increases in FI in patients with spondylolisthesis, although methods and anatomical levels varied across studies. Compensatory hypertrophy of the erector spinae and psoas major was observed, particularly in isthmic cases.

Conclusions: These findings support the potential role of muscle health in maintaining spinal stability and suggest that targeted rehabilitation strategies addressing paraspinal muscle alterations may improve clinical outcomes in patients with LS.

Background: Deep vein thrombosis (DVT) following total knee arthroplasty (TKA) remains a major postoperative complication. Conventional risk assessment tools such as the Caprini score show limited predictive performance (AUC 0.65–0.72). We developed a multimodal deep learning framework that integrates early postoperative radiographs with clinical data to improve DVT risk stratification.

Methods: This single-center retrospective cohort study analyzed 1200 patients undergoing primary unilateral TKA (DVT incidence: 18.0%) from January 2018 to June 2023. A dual-branch architecture was implemented: ViT-B/16 or ResNet50 processed standardized radiographs (metal artifact suppression; 512 × 512 resolution), while Clinical-BERT encoded structured electronic medical record (EMR) representations. A dynamic attention fusion module generated sample-specific modality weights (α) for feature fusion (α·v_img + (1 − α)·v_txt). Performance was evaluated on a stratified test set (n = 180) against the Caprini score, unimodal models, and a nonattention concatenation fusion baseline. AUCs were compared using the DeLong test, and sensitivity/specificity differences were assessed using the McNemar test.

Results: The multimodal model achieved an AUC of 0.89 (95% CI: 0.85–0.92; DeLong p < 0.001 vs. all comparators), sensitivity 83% (76%–89%), specificity 88% (82%–93%), and F1-score 0.79. It identified 91.7% (11/12) of DVT cases labeled low-risk by Caprini. The learned attention coefficient α suggested modality reliance patterns associated with specific findings (e.g., higher α in cases with prosthesis–bone lucency > 2 mm; higher text contribution in cases with D-dimer > 1.0 mg/L), but these associations do not establish causality. Anatomical heatmaps consistently localized high-risk regions, particularly the popliteal vein projection area and tibial interface.

Conclusion: This attention-based multimodal model integrates biomechanical (radiographic) and biochemical/clinical (EMR-derived) signals to improve early postoperative DVT risk prediction while providing interpretable anatomical cues.

Objective: This study aimed to investigate the clinical and biomechanical effect of medial fixed-bearing unicompartmental knee arthroplasty (UKA) on the patellofemoral joint (PFJ). However, whether patellofemoral joint (PFJ) degeneration should be considered a contraindication for UKA remains controversial. In addition, the biomechanical effects of UKA on PFJ stress distribution have not been fully elucidated.

Method: Thirty-two patients (35 knees) who underwent medial fixed-bearing UKA were included with a mean of 4.5 years follow-up. The clinical parameters including the Oxford Knee Score (OKS), Western Ontario and McMaster Universities Osteoarthritis Index score (WOMAC), and Visual Analogue Scale (VAS), and radiographic parameters including lateral patellofemoral angle (LPFA), congruence angle (CA), lateral patellar tilt angle (LPTA), posterior tibial slope (PTS), and hip-knee-ankle (HKA) angle were compared. Finite element analysis (FEA) was performed for further investigating PFJ stress change after medial fixed-bearing UKA.

Results: At the final follow-up, the clinical and radiographic parameters were significant improvement compared to the preoperative measurements (p < 0.05); there were not significantly different in the clinical parameters between patients with and without PFJ arthropathy (p > 0.05). As the knee varus angle was gradually corrected using UKA, the excessive stress in the medial PFJ was partially transferred to the lateral PFJ, and the stress in the medial and lateral PFJ tended to be balanced.

Conclusion: Medial fixed-bearing UKA can improve clinical outcomes and optimize the PFJ alignment and stress distribution. The presence of PFJ arthropathy did not compromise the clinical outcomes. However, the presence of preoperative lateral PFJ arthropathy has a risk of inferior clinical outcomes due to increasing stress on the lateral PFJ after medial fixed-bearing UKA.

Objective: High-grade isthmic spondylolisthesis remains surgically controversial, and evidence on minimally invasive, single-level reduction and fusion with mid-term follow-up remains limited. This study aimed to investigate the efficacy and safety of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and percutaneous pedicle screw fixation for high-grade (Meyerding Grade III) spondylolisthesis.

Methods: This prospective observational case series included 14 consecutive patients with Meyerding Grade III isthmic spondylolisthesis treated at a single institution between 2014 and 2019. All patients underwent monosegmental MIS-TLIF with percutaneous pedicle screw fixation. Outcome measures included VAS (back and leg pain), ODI, slip percentage, Dubousset lumbosacral angle, and other spinopelvic parameters. Pre- and postoperative comparisons were performed using paired t-tests (p < 0.05).

Results: Fourteen patients had a mean age of 54.9 years with a diagnosis of isthmic spondylolisthesis, Meyerding Grade III. The average estimated blood loss was 273.93 mL (range, 197–380 mL). The average operating time was 142.14 min (range, 125–165 min). The average follow-up duration was 43.5 months, with a range of 38–60 months. In most cases, radicular pain was significantly relieved postoperatively. The mean ODI scores decreased from preoperative 65.56% to postoperative 7.93%. All cases achieved near-anatomic reduction, and lumbosacral lordosis was significantly corrected. The average slip percentage improved from 64.36% (preop) to 5.88% (postop), and the average Dubousset-LSA increased from 81.96° (preop) to 105.93° (postop). The overall sagittal profile improved dramatically.

Conclusions: MIS-TLIF and percutaneous pedicle screw fixation may offer a safe and effective treatment option for high-grade spondylolisthesis, with satisfactory clinical and radiological outcomes.

Objective: Preoperative identification of infectious nonunion remains challenging, particularly in patients without overt clinical signs of infection. Conventional inflammatory markers alone often provide insufficient diagnostic accuracy, creating uncertainty in surgical planning. This study aimed to develop and internally evaluate a predictive model combining novel and conventional biomarkers for preoperative diagnosis of infectious nonunion in long bone fractures. We hypothesized that integrating procalcitonin (PCT) with classical inflammatory markers would enhance diagnostic accuracy.

Methods: We retrospectively analyzed 276 patients treated for femoral or tibial nonunion after internal fixation (2018–2023). Patients were randomly divided into a model-development cohort (n = 221) and a hold-out test cohort (n = 55). A multivariable logistic regression model was built using serum levels of PCT, interleukin-6 (IL-6), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). Model performance was assessed by AUC, calibration plots, and decision curve analysis.

Results: In the model-development cohort, 110 patients had infectious nonunion and 111 had aseptic nonunion. Infected cases had significantly higher biomarker levels (p < 0.001). Among single markers, ESR had the best performance (AUC ~0.79), followed by PCT (~0.71), IL-6 (~0.62), and CRP (~0.61). The best multivariable model included PCT, CRP, and ESR, achieving an AUC of ~0.85 (95% CI ~0.80–0.90). Bootstrapping confirmed minimal overfitting (corrected AUC ~0.84). In the hold-out test cohort, this model maintained strong performance (AUC ~0.85, 95% CI ~0.72–0.96), with ~75% sensitivity and 85% specificity—superior to any single biomarker. Calibration plots showed good agreement, and decision analysis demonstrated higher clinical benefit than using individual markers or treating all patients.

Conclusion: The PCT + CRP + ESR model reliably distinguishes infectious from aseptic nonunion, outperforming traditional markers alone. It offers a practical, accurate preoperative tool for infection screening, supporting more informed surgical decision-making. In clinical use, interpretation should be based on the predicted probability generated by the combined model rather than isolated elevation of individual biomarkers. Further prospective and external validation is warranted.

Objective: Unilateral laminotomy with bilateral decompression (ULBD) is a standard procedure for relieving neural compression. Recently, minimally invasive techniques such as Arthroscopic-assisted uniportal spinal surgery (AUSS) and unilateral biportal endoscopy (UBE) have gained attention as alternatives to traditional methods. However, limited data are available on the comparative clinical and radiological outcomes of AUSS and UBE for ULBD in patients with lumbar spinal stenosis (LSS). This study aimed to compare these outcomes in patients with LSS who underwent ULBD using either AUSS or UBE, with a follow-up period of 2 years.

Methods: This retrospective study evaluated 87 patients with LSS who underwent ULBD using either the AUSS or UBE technique between March 2021 and November 2022. Patients were followed up for at least 2 years. Perioperative outcomes, pain relief assessed using the VAS and ODI, and radiological parameters, including the Cross-Sectional Dural Area (CSA), Disc Height Index (DHI), Translation Motion, Preservation Rate of Facet Joint, and Radiological Progression, were compared between the two groups. Statistical analysis was performed using IBM SPSS version 29. Continuous variables were analyzed using the independent-samples t-test or Mann–Whitney U test, and categorical variables were analyzed using the chi-squared test or Fisher's exact test.

Results: Both AUSS and UBE techniques showed significant reductions in VAS and ODI scores postoperatively, with no significant differences between the groups at any follow-up. The AUSS group had shorter operative times, less blood loss, and smaller incisions compared to the UBE group. Postoperative CSA of the dural sac increased similarly in both groups. Radiological progression was observed in one patient in the AUSS group and one in the UBE group, but no major complications occurred. More than 90% of patients in both groups reported favorable outcomes based on the Modified Macnab criteria at the final follow-up.

Conclusions: AUSS and UBE are both effective minimally invasive techniques for treating LSS through ULBD, achieving similar clinical and radiological outcomes at the two-year follow-up. Although AUSS demonstrated perioperative advantages, including shorter operative time and lower estimated blood loss, patient-centered clinical outcomes were comparable between the two groups.

Objective: Morphological studies of Weber Type A lateral malleolar fractures (LMFs) are scarce, and no classification criteria exist specifically for this fracture type. Therefore, our objective is to describe the distribution of Weber Type A LMF and propose a classification based on three-dimensional computed tomography (CT) and fracture mapping techniques.

Methods: We retrospectively reviewed 586 patients presenting with lateral malleolar fractures at our hospital between June 2016 and May 2024. CT data were reconstructed and reduced using software, and fracture lines were delineated. Fracture lines from all patients were superimposed to generate fracture maps and heatmaps. Fracture section area (FSA) was also measured for each case. Using the Kolmogorov–Smirnov test to assess the normality of the data distribution and the Kruskal–Wallis test to compare the FSA values among different fracture subtypes.

Results: A total of 81 Weber type A LMFs were included. Based on the fracture morphology and its relationship with the fibular obscure tubercle (FOT) and inferior tip of the fibula (ITF), Weber type A LMFs were classified into three types: Type I: Anteroinferior (25 cases, 30.9%); Type II: Posteroinferior (32 cases, 39.5%); Type III: Metaphyseal (24 cases, 29.6%).

Conclusions: This study revealed the morphological characteristics of Weber type A LMF, enhanced understanding of the underlying injury mechanisms, and provided guidance for making diagnostic and therapeutic decisions.

Objective: Early diagnosis of spinal tuberculosis remains challenging, and inappropriate percutaneous vertebral augmentation can aggravate lesions and worsen clinical symptoms. Relevant clinical evidence on subsequent standardized management remains limited. This study aimed to investigate the clinical efficacy and prognostic outcomes of different treatment strategies in patients with spinal tuberculosis following inappropriate percutaneous vertebral augmentation, and to analyze the clinical characteristics of the patients and provide clinical data for the differential diagnosis of spinal tuberculosis.

Methods: The clinical data of 53 patients with spinal tuberculosis who underwent vertebral augmentation between January 2012 and January 2024 were retrospectively analyzed. There were 26 males and 27 females, with a mean age of 70.33 ± 5.88 years (range 53–86 years). Thirty-one patients had thoracic tuberculosis, and 22 had lumbar tuberculosis. According to the ASIA Impairment Scale, 7 patients were grade B, 15 were grade C, 24 were grade D, and 7 were grade E. At admission, 52 patients had elevated erythrocyte sedimentation rates (ESRs) and C-reactive protein (CRP) levels, 36 had positive T-SPOT results, and 1 patient had a normal ESR and CRP level and negative T-SPOT result. Twenty-seven patients had single-vertebral involvement, and 26 had multiple-vertebral involvement. Patients were divided into two groups, and a retrospective cohort comparative analysis was conducted: Surgical group (35 patients) received posterior spinal canal decompression, bone graft fusion, and internal fixation; conservative group (18 patients) received non-surgical treatment. Outcomes included ESR, CRP level, VAS score, ASIA grade, and MBI score. Enumeration data were analyzed with the χ² test for intergroup differences in proportions. Normally distributed continuous data were compared using the independent samples t-test. Non-normally distributed continuous data were analyzed using the Mann–Whitney U test. Paired comparisons were performed using the Wilcoxon signed-rank test. Repeated measures data were analyzed using the rank-sum test.

Results: The follow-up period ranged from 18 to 36 months. Early postoperative increases in the ESR and CRP level were significantly greater in the surgical group than in the conservative group, but inflammatory marker levels normalized within 3–6 months in both groups. Before treatment, there were no significant differences in the ESR, CRP level, VAS score, MBI, or ASIA grade between the groups (all p > 0.05). At 3 months and at the final follow-up, the ESR, CRP level, and VAS score decreased significantly and the MBI and ASIA grades improved significantly in both groups (all p < 0.05). The MBI was significantly better in the surgical group at 3 months (p < 0.05). At the final follow-up, no significant differences were found between the groups in any index (all p > 0.05).

Conclusion: This retrospective cohort study shows that compared with conservative treatment, surgical treatment results in faster symptomatic and functional recovery in patients with neurological compression after mismanaged vertebral augmentation for spinal tuberculosis. For patients without significant neurological compression or those who are unfit for surgery, conservative treatment achieves satisfactory long-term efficacy, although the recovery time is longer. Long-term outcomes are comparable between the two strategies.

Objective: Given the paucity of prospective randomized evidence on chewing gum for postoperative bowel recovery in elderly spinal fusion patients, this study aimed to assess the efficacy of chewing gum in improving bowel function recovery in the elderly after posterior lumbar fusion surgery.

Methods: This study enrolled 119 elderly patients following posterior spinal fusion surgery between September 2023 and May 2025, and they were randomly assigned to either group 1 (chewing gum) or group 2 (control). The time for the first fluid intake, first oral intake, first sitting up, first bowel sounds, first flatus, and first defecation was recorded as outcome measures. Besides, the anesthesia usage controlled by patients after surgery, abdominal pain, distension, surgical wound pain, nausea, and abdominal girth were assessed and recorded at 24, 48, 72 h after surgery. Statistical analyses were performed using independent t-test, Mann–Whitney U test, Chi-square test, or Fisher's exact test, as appropriate.

Result: There are no significant differences observed between the chewing gum and control groups in patient-controlled anesthesia usage, abdominal pain scores, distension scores, surgical wound pain scores, nausea scores, or abdominal girth (p > 0.05). Similarly, postoperative recovery parameters, including time to first fluid intake, oral intake, sitting up, first bowel sounds, first flatus, and first defecation, showed no statistically significant differences (p > 0.05).

Conclusion: In this single-center randomized controlled trial, chewing gum did not show a statistically significant effect on early postoperative bowel function recovery in elderly patients undergoing posterior lumbar fusion surgery.

Objective: Percutaneous endoscopic lumbar discectomy (PELD) is a preferred minimally invasive surgery for lumbar disc herniation (LDH); however, postoperative recurrence, nerve root damage, and hyperesthesia continue to present key clinical challenges. Chitosan represents a novel preventive approach against postoperative complications. This study aimed to assess the clinical efficacy of ultrasound-guided percutaneous endoscopic interlaminar discectomy (PEID) plus medical chitosan in treating lumbar 4–5 disc herniation (L4-5 LDH).

Methods: Totally, 200 L4-5 LDH patients were prospectively recruited and randomly divided into the control group (ultrasound-guided PEID) and observation group (ultrasound-guided PEID plus medical chitosan). Low back and leg pain and lumbar dysfunction were assessed preoperatively and postoperatively using Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Japanese Orthopaedic Association (JOA). Efficacy and postoperative complications were evaluated according to the modified MacNab criteria. Logistic regression analyses identified the risk factors. Mann–Whitney U test was used for inter-group comparisons, and the Kruskal–Wallis test for timepoint comparisons.

Results: The two groups showed significant differences in pre-treatment Pfirrmann classification and operation time. As time progressed, patients exhibited reduced VAS and ODI scores and increased JOA scores postoperatively. Significant differences were observed in VAS, JOA, and ODI scores in the observation group at 2 weeks postoperatively. The observation group demonstrated superior treatment efficacy and a lower complication incidence than the control group. Age, disease course, and postoperative bleeding were independent risk factors affecting clinical efficacy of ultrasound-guided PEID plus chitosan.

Conclusion: Ultrasound-guided PEID plus medical chitosan reduces postoperative pain and perioperative complications, demonstrating superior clinical efficacy.

Introduction: Although pelvic landmarks have traditionally been used to estimate the femoral head center (FC), their reliability may be limited in patients with developmental dysplasia of the hip (DDH). In contrast, femoral-based reference methods have been insufficiently investigated. This study aimed to evaluate the feasibility and clinical utility of estimating the FC location in DDH using a three-dimensional model derived from trochanteric landmarks.

Methods: We retrospectively analyzed 128 femurs from 84 female patients with DDH (mean age, 36.9 years) who underwent curved periacetabular osteotomy (CPO) from April 1, 2010, to September 30, 2020, and had no symptoms involving the spine or knee. The FC was estimated using multiple regression models based on the three-dimensional coordinates (x, y, and z) of the greater and lesser trochanter tips. Differences between the estimated and actual FC positions were assessed along all three axes.

Results: Correlation coefficients between the estimated and actual FC ranged from 0.725 to 0.875 across the three directions. The mean absolute error was 2–3 mm, with greater errors observed in the anteroposterior direction than in the craniocaudal direction. An estimation error within 3 mm may be considered relatively small in the context of clinically acceptable ranges reported in previous studies for restoring femoral offset and leg length during total hip arthroplasty (THA), supporting the practical applicability of this method in preoperative planning.

Conclusion: The accuracy of the present approach was comparable to that reported in healthy populations and exceeded that of previous pelvic landmark-based regression techniques. This trochanter-based three-dimensional method enables clinically acceptable estimation of the FC in patients with DDH and may serve as a useful adjunct for planning of the femoral component when the native FC is difficult to identify.

Background: Parosteal osteosarcoma (PAOS) is a rare and low-grade primary bone malignant tumor that typically occurs in the distal femur. Traditional reconstruction options for distal femur PAOS include distal femoral replacement (DFR), autografts, and allografts, but issues such as functional sacrifice, insufficient mechanical strength, and low bone union rate limit their further clinical application. 3D-printed prosthesis, due to the matching shape of various bone defects, could be a novel strategy to reconstruct the hemicortical defect after distal femur PAOS tumor resection. In this study, we designed a 3D-printed strut-type prosthesis (3DPSP) to repair the hemicortical defect and evaluated the mid-term effect in distal femur PAOS.

Methods: A retrospective analysis was conducted on patients diagnosed with PAOS at the distal femur between April 2018 and January 2021. Six patients received DFR and six patients received customized 3DPSP reconstruction. Clinical outcomes including oncology status, defect lengths, and ranges of motion of the knee, Musculoskeletal Tumor Society (MSTS) scores, and complications were recorded. X-ray was performed to evaluate the position and stability of the prosthesis and T-SMART was applied to assess the interface osteointegration between prosthesis and bone.

Results: A total of 12 patients were enrolled in this study with an average follow-up of 42.1 ± 11.8 months, ranging from 22 to 59 months. In the 3DPSP group, the average operation time was 2.3 ± 0.4 h; the intraoperative blood loss was 175.0 ± 82.2 mL. The average range of motion of the knee was 0°–123° and the mean MSTS score was 28.3 ± 1.6. Compared to the DFR group, the 3DPSP group exhibited significantly less intraoperative blood loss and superior functional recovery.

Conclusions: In this study, we designed a novel 3DPSP to reconstruct the hemicortical defect after distal femur PAOS resection. The mid-term follow-up result demonstrated that this prosthesis could be an effective reconstruction option for distal femur PAOS patients because of the restored limb function and favorable bone-prosthesis integration. Further observation of this novel prosthesis is needed.

Objective: The biomechanical interaction between coronal alignment and short extension stem use in total knee arthroplasty (TKA) remains insufficiently understood, particularly regarding the balance between tibial component stability and stress shielding. This study aims to investigate the effects of varying bone cut angles on the tibial side and the use of a short extension stem on tibial component displacement and stress distribution. Additionally, it will examine the stresses experienced by both cortical and cancellous bone during primary TKA, employing three-dimensional finite element analysis and elucidating the biomechanical effects of combining kinematic alignment (KA) with a short extension stem in TKA.

Methods: A healthy adult female volunteer was selected to create a tibial model of the left knee joint utilizing three-dimensional reconstruction and finite element analysis software. Six finite element models were developed based on a standard tibial plateau prosthesis and a tibial prosthesis with a 30 mm short extension stem. These models were categorized according to mechanical alignment (MA), KA, and a 3° valgus alignment. The simulations were designed to replicate the loads and constraints experienced during weight-bearing activities of the lower limb. Subsequently, we analyzed the displacement and stress distribution of the tibial prosthesis and examined the stress distribution within both the tibial cortical bone and cancellous bone.

Result: In the KA model, there was a notable increase in displacement, an elevation in mean cortical bone Von Mises stress, and a reduction in mean component Von Mises stress when compared to both the MA and the 3° valgus alignment model. The design of the short extension stem effectively decreased the displacement of the prosthesis but led to increased stress on the prosthesis itself. Additionally, this design led to a reduction in stress on the cortical bone, suggesting a more pronounced stress-shielding effect.

Conclusion: The application of KA in TKA will increase prosthetic displacement and reduce the stress-shielding effect, while the application of short extension stem will reduce prosthetic displacement and increase the stress-shielding effect. The combination of the KA and short extension stem may play a complementary role, but this needs further research to confirm.

Objectives: Prosthetic impingement and dislocation remain prevalent complications following total hip arthroplasty (THA). The “safe zone” concept guiding acetabular component placement is predicated on static body positions, while neglecting the kinematic changes in pelvic angles throughout the stand-to-sit (STS) transition cycle. This static-centric approach constitutes a primary contributing factor to THA-related complications. Consequently, investigating the kinematic regularity of pelvic motion across the entire STS cycle is of particular significance for optimizing surgical strategies and improving postoperative outcomes.

Methods: Dynamic pelvic angles are analyzed in 10 healthy individuals performing STS using optical motion capture combined with biodynamics simulations. The skeletal model is scaled to each subject, and inverse kinematics is used to compute motion trajectories, from which the time-varying characteristics of sacral slope (SS), pelvic incidence (PI), and pelvic tilt (PT) angles are extracted.

Results: The skeletal model of the STS movement cycle is simulated, revealing the nonlinear variations in pelvic characteristic angles. Notably, the variation curves of SS and PT angles both exhibit distinct stationary points during the critical phase of the movement cycle, with the two parameters showing opposite changing trends. Specifically, PT angle decreases sharply to a trough within the 44.48%–53.19% interval of the movement cycle and then gradually rebounds from this stationary point. In contrast, SS angle increases first and then decreases, with its stationary point highly coinciding with that of PT. At the trough stationary point of PT or SS, body center of gravity (COG) trajectory exhibits a strong correlation with PT or SS kinematics and synchronous transitions in displacement velocity and direction, highlighting the crucial role of pelvic posture adjustment in body COG regulation.

Conclusions: A biomechanical framework for investigating the kinematic characteristics of pelvic angles during the STS task is proposed. In healthy individuals, the kinematic patterns of pelvic motion during STS demonstrate prominent nonlinear characteristics, accompanied by distinct stationary points in the pelvic characteristic angles around the mid-STS phase. The current acetabular safe zone is insufficient to account for dynamic variations in pelvic orientation, and the identified critical stationary points of pelvic angles during the mid-STS phase may provide theoretical support for preoperative planning and postoperative rehabilitation in patients undergoing THA.

Objectives: Patellar resurfacing in total knee arthroplasty (TKA) remains a debated topic. Medial stabilized (MS) implants have gained popularity in the United States in recent years as they more closely mimic native femoral-tibial and patella-femoral knee kinematics. However, little is known about the effects of patellar resurfacing with a specific round-on-round, one-to-one congruent, medial stabilized implant. The purpose of this study was to evaluate whether patellar resurfacing influences pain, function, patient-reported outcomes, and perioperative outcomes in patients undergoing primary MS TKA with this implant.

Methods: A retrospective cohort study was conducted on 107 patients undergoing primary MS TKA with the Sphere implant (Medacta International, Castel San Pietro, SZ). Patients were divided into resurfacing (R, n = 51) and non-resurfacing (NR, n = 56) groups. Outcomes included pain scores, range of motion (ROM), patient-reported outcome measures (PROMs), and perioperative variables. PROs collected included PROMIS Physical Function and Pain Interference CATs, Knee Society Score (KSS), Visual Analog Scale (VAS) pain score (0–100), Knee injury and Osteoarthritis Outcomes Score (KOOS), Forgotten Joint Score (FJS), patellofemoral pain questionnaire, and the Samsung Medical Center (SMC) patellofemoral scoring system. Comparative statistical analyses were performed using chi-square tests, t-tests, and Mann–Whitney U tests.

Results: No significant differences were found in postoperative pain scores (VAS), opioid consumption, or overall PROMs between groups. However, the non-resurfacing group demonstrated greater ROM at 12 months (121.5° vs. 116.4°, p = 0.03) and higher KOOS ADL and symptom subscales. Resurfacing was associated with increased operative time (p < 0.001) and tourniquet time (p = 0.03); hospital LOS was shorter in the resurfacing group by six hours (p < 0.05).

Conclusion: In MS TKA, patellar resurfacing did not confer significant advantages in pain relief or functional outcomes at one year. These findings support an individualized approach to patellar resurfacing in MS TKA as each technique is deemed non-inferior.

Objective: 3D joint space width (JSW) mapping quantifies structural narrowing in knee osteoarthritis (OA), but the effect of surface mesh resolution on measurement reliability and precision remains unclear. This study assessed how mesh resolution influences 3D JSW measurements, whether effects differ by metric and OA severity, and which resolutions best preserve OA group-level discrimination and subject-level agreement.

Methods: Knees with medial knee OA (KL grades 0–4) were analyzed. For each knee, 3D JSW maps were generated on a 0.1 mm reference mesh and seven coarser meshes (0.3, 0.5, 0.7, 1.0, 2.0, 3.0, and 4.0 mm). Minimum and median JSW (minJSW, medJSW) were calculated within a standardized medial region and compared to the reference. Systematic error, agreement (Bland–Altman), and subject-level interchangeability were evaluated across resolutions for the overall cohort and early versus advanced OA subgroups. Absolute-error thresholds were set at 0.2 mm (sensitivity) and 0.5 mm (clinical significance). Mesh-by-severity interactions were analyzed using mixed-effects models, and group-level discrimination was assessed at each resolution.

Results: Seventy-two knees from 54 patients (mean age 65 ± 10.4 years; 48.6% advanced OA) were included. The 0.1 mm reference mesh had excellent geometric fidelity (RMS deviation 0.0011 ± 0.0010 mm) and high vertex density (median 118,300 vertices), which dropped to 14,848 at 0.3 mm, 5033 at 0.5 mm, and 72 at 4.0 mm. From 0.1 to 4.0 mm, medJSW increased from 4.07 ± 0.77 mm to 5.14 ± 0.96 mm and minJSW from 1.98 ± 0.81 to 2.34 ± 0.81 mm, converging at 0.3 mm. Subject-level agreement for medJSW declined beyond 0.3 mm: at 0.5 mm and coarser meshes, ≥ 44.4% of knees exceeded the 0.2 mm error threshold; at 0.7 mm and coarser meshes, ≥ 12.5% exceeded the 0.5 mm threshold. In contrast, minJSW remained within the 0.5 mm clinical threshold through 1.0 mm. Early OA showed a larger absolute medJSW inflation (p = 0.023), whereas advanced OA had greater relative minJSW error (p < 0.05). Group-level OA discrimination remained preserved at all resolutions (p < 0.001), while subject-level agreement deteriorated at coarser meshes.

Conclusions: Mesh resolution significantly influences 3D JSW measurements, with effects modulated by selected metric, disease stage, and level of analysis. Using a rigorous 0.1-mm reference mesh, specific thresholds were established: a 0.3-mm mesh provided the most consistent performance across all conditions; a 0.5-mm mesh may be acceptable for medJSW under a less stringent error tolerance; and up to 1.0 mm sufficed only for identifying the narrowest point (minJSW). At coarser resolutions, baseline JSW overestimation can be large enough to alter perceived structural severity of medial compartment narrowing, carrying risks for clinical misinterpretation and treatment decisions.

Background: Pauwels type III femoral neck fractures (P3FNFs) are one of the common types of femoral neck fractures (FNF) caused by high-energy violent factors. This study aims to evaluate the efficacy of inverted cannulated cancellous screw (ICCS) assisted transversal cannulated screw (TCS) perpendicular to the fracture line in young adults with Pauwels type III femoral neck fractures.

Methods: Construct an internal fixation-fracture model through finite element analysis (FEA) and biomechanical test (BT) to simulate the stress environment of the human hip joint, and utilize the femoral neck system (FNS) model as a control to predict the biomechanical properties of ICCS + TCS. From January 2023 to December 2024, 21 patients with P3FNFs treated with ICCS + TCS were collected, and their recent radiographic and clinical outcomes were evaluated. The experimental data underwent statistical analysis using one-way ANOVA and independent samples t-test.

Result: ICCS + TCS exhibits biomechanical trends in FEA and BT that are essentially consistent with those of FNS. ICCS + TCS has stronger torsional stiffness and lower overall deformation, But the resistance to vertical shear force is weaker than FNS. All patients in this study successfully completed the surgery without complications such as vascular or nerve injuries. The follow-up period ranged from 8 to 25 months. The hip joint flexion-extension ROM, internal–external rotation ROM, and Harris score all significantly increased (p < 0.05). The shortening length of the femoral neck was 3.87 ± 0.44 mm.

Conclusion: ICCS + TCS exhibits biomechanical trends compared to FNS; meanwhile, it has stronger torsional resistance and load-bearing deformations. Simultaneously, ICCS + TCS has demonstrated favorable outcomes in clinical treatments. This study offers a novel approach for the treatment of P3FNFs.

Objective: Lumbar fusion combined with topping-off dynamic stabilization has been used to reduce adjacent-segment stress in lumbar degenerative diseases. However, traditional pedicle screw-based topping-off surgery may require relatively extensive posterior exposure, which can increase soft-tissue injury and delay postoperative recovery. This study aimed to evaluate the feasibility and effectiveness of low-profile lumbar fusion using cortical bone trajectory screws (CBTs) and pedicle screw (PS) internal fixation combined with Coflex dynamic stabilization, compared to traditional PS-based topping-off.

Methods: A retrospective cohort study was conducted using data from patients with lumbar degenerative diseases treated between December 2021 and January 2023. Patients who underwent either the low-profile topping-off procedure or traditional topping-off surgery were enrolled. Demographic data, perioperative parameters, radiographic outcomes, complications, and clinical outcomes were collected and compared between the two groups. Statistical analyses included Student's t-test, chi-square test, two-way analysis of variance, multivariable linear regression, and binary logistic regression.

Results: A total of 229 patients undergoing single-level L4/L5 fusion (104 in the low-profile group and 125 in the traditional group) were followed for 35.69 ± 4.76 months (range, 24–40 months). Baseline characteristics, including age, sex, bone mineral density (BMD), diagnosis distribution, and follow-up duration, were comparable between groups (p > 0.05). Compared with the traditional group, the low-profile group demonstrated improved perioperative outcomes, with less intraoperative blood loss, shorter incision length, lower drainage volume, and shorter postoperative hospital stay, while operative time was similar. Radiographically, the low-profile group showed a higher fusion success rate at final follow-up (Bridwell Grade I + II: 91.3% vs. 80.8%). Adjacent-segment analyses indicated better preservation of cranial adjacent-segment radiographic parameters (L3/4) at 24 months in the low-profile group, whereas the overall adjacent segment degeneration (ASD) incidence did not differ significantly between groups. Both groups achieved significant improvements in Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Japanese Orthopedic Association Score (JOA); although postoperative back pain VAS and ODI were statistically lower in the low-profile group, leg pain VAS, JOA, and overall complication rates were comparable. Multivariable regression adjusting for age, sex, BMD, diagnosis type, and baseline ODI showed that surgical approach remained independently associated with final ODI, while no significant association with overall complications was observed.

Conclusion: Low-profile topping-off surgery is as effective as traditional topping-off for lumbar degenerative diseases, which has the strength of being less invasive and enabling more rapid recovery.

Background: Atlantoaxial instability or dislocation requires reliable posterior stabilization and fusion to prevent neurological deterioration. Although conventional Goel–Harms posterior fixation provides effective biomechanical stability, it usually requires extensive posterior cervical muscle dissection and may be associated with substantial blood loss, postoperative axial pain, and soft-tissue morbidity. Despite the advantages of minimally invasive endoscopic techniques in spinal surgery, clinical evidence regarding their application in the management of AAI/D remains limited. In this study, we report a clinical series of endoscopic-assisted atlantoaxial lateral mass fusion, provide a detailed description of the key surgical steps, and evaluate its technical feasibility, safety, and early clinical outcomes.

Methods: Sixteen patients diagnosed with AAI/D underwent endoscopic-assisted posterior atlantoaxial fusion. The procedure utilized a uniportal endoscopic system through a 2.5–3.0 cm incision, enabling direct visualization of the C1–C2 lateral mass joint, precise screw placement, and intra-articular bone grafting under continuous irrigation. Radiographic parameters, neurological function (JOA), pain (VAS), and neck disability (NDI) scores were assessed pre- and postoperatively.

Results: All surgeries were successfully completed without intraoperative neurovascular injury or hardware malposition. The mean operative time was 103.06 ± 9.55 min, and the mean blood loss was 40.06 ± 9.28 mL. The atlantodental interval (ADI) decreased from 5.14 ± 1.51 mm preoperatively to 3.37 ± 0.52 mm postoperatively (p < 0.001), and C1–C2 joint height increased from 2.98 ± 0.27 mm to 4.37 ± 0.49 mm (p < 0.001). At 3 months, bone fusion was achieved in 93.8% of patients. Clinical outcomes improved compared with preoperative values, including JOA score (8.44 ± 0.89 to 13.31 ± 1.20), VAS score (8.00 ± 0.73 to 2.25 ± 0.45), and NDI score (31.88 ± 1.93 to 12.88 ± 1.26).

Conclusion: This study introduces a novel minimally invasive technique for managing atlantoaxial instability using uniportal endoscopic-assisted posterior fusion. The combination of direct endoscopic visualization, accurate screw–rod fixation, and controlled intra-articular bone grafting offers reliable joint stabilization with reduced tissue disruption. Clinical outcomes suggest this approach may facilitate rapid recovery and improved perioperative safety, offering a valuable addition to current surgical strategies for AAI/D.