JBJS

Risk Factors for Nonunion Following Lateral Locked Plating of Distal Femoral Fractures: A Bayesian Analysis of 560 Patients

J Bone Joint Surg Am. 2026 Feb 4;108(3):235-243. doi: 10.2106/JBJS.25.00498. Epub 2025 Nov 18.

ABSTRACT

BACKGROUND: Lateral locked plating remains an important treatment strategy for distal femoral fractures but has been associated with nonunion rates ranging from 6% to 20%. The objective of this study was to identify factors associated with nonunion following lateral locked plating of distal femoral fractures with use of a Bayesian analysis.

METHODS: All consecutive patients ≥18 years of age who were treated with lateral locked plating for a distal femoral fracture at 2 Level-I trauma centers between 2006 and 2024 and who had ≥3 months of follow-up were included. Multivariable Bayesian logistic regression analysis was performed to identify factors associated with nonunion, which was defined as a reoperation to promote healing, and the results are reported as odds ratios (ORs) with 95% credible intervals (CrIs). Probabilities of >95% were considered very strong evidence of an association with nonunion, and probabilities of 90% to 95% were considered strong evidence.

RESULTS: A total of 560 patients (median age, 68 years; 29% male; 90% White; 97% non-Hispanic; 41% with distal periprosthetic fractures) were included. Fifty-four patients (9.6%) underwent reoperation to promote healing. There was very strong evidence that multifragmentary comminution of the metaphysis (versus simple fracture: OR, 2.60; 95% CrI, 0.91 to 8.06), medial cortical comminution of >0 to 25 mm (versus 0 mm: OR, 3.11; 95% CrI, 1.35 to 7.48), and varus (lateral distal femoral angle [LDFA] of ≥84°: OR, 3.04; 95% CrI, 1.46 to 6.51) or valgus (LDFA of ≤78°: OR, 2.42; 95% CrI, 0.96 to 5.99) malalignment increased the odds of nonunion. A screw density of ≤0.60 proximal to the working length reduced the odds of nonunion (versus ≥0.81: OR, 0.40; 95% CrI, 0.16 to 0.95), although the size and certainty of this effect varied in the sensitivity analysis that utilized alternative thresholds. There was strong evidence that obesity increased the odds of nonunion (OR, 1.64; 95% CrI, 0.86 to 3.13) and that intact wedge fractures reduced the odds of nonunion (versus simple fracture: OR, 0.35; 95% CrI, 0.05 to 1.74).

CONCLUSIONS: One in 10 patients developed nonunion and underwent reoperation to promote healing. Surgeons should restore coronal plane alignment and may consider augmenting fixation in the presence of multifragmentary comminution. Constructs in which all screw holes proximal to the working length are filled should be avoided, although the optimal configuration remains unclear and depends on other construct characteristics influencing biomechanics. Overall, the small to moderate effect sizes highlight the multifactorial etiology of nonunion following lateral locked plating of distal femoral fractures.

LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

PMID:41636737 | PMC:PMC12834285 | DOI:10.2106/JBJS.25.00498

The Ultrasound-Assisted Patellar Glide Test: A Novel Examination Method for Quantifying Patellar Instability

J Bone Joint Surg Am. 2026 Feb 4;108(3):227-234. doi: 10.2106/JBJS.25.00707. Epub 2025 Nov 24.

ABSTRACT

BACKGROUND: Patellofemoral instability is a difficult problem to assess because of its dynamic nature, which is not easily quantified using physical examination techniques. This study aimed to describe and evaluate a novel examination method using stress ultrasonography to quantify patellar instability. The secondary aim was to assess the relationship of stress ultrasonography measurements with clinical and morphologic risk factors for patellar instability.

METHODS: Knees with symptomatic patellar instability underwent the ultrasound-assisted patellar glide test. In this test, the patella was translated laterally from its resting position during ultrasound visualization until an endpoint was reached. The medial patellofemoral distance (MPFD) was used to quantify the gap between the medial boundary of the patella and the trochlea, and the difference in MPFD between the resting (unloaded) and loaded conditions was defined as the delta MPFD. Measurements were compared with those in asymptomatic contralateral knees of patients with unilateral instability, asymptomatic knees after patellar stabilization surgery, and control knees. Regression analyses assessed for relationships of MPFD with morphological and clinical risk factors. Receiver operating characteristic (ROC) curve analysis assessed the ability of stress ultrasonography measurements to discriminate between knees with and without symptomatic patellar instability.

RESULTS: Four hundred and seventy-seven knees in 277 patients were included in this study; 173 of the knees had patellar instability (patient age, 24 ± 8 years; 72% female). Delta MPFD was 3 times greater in knees with patellar instability (median, 3.3 mm [95% confidence interval, 3.1 to 3.4 mm]) than in the contralateral asymptomatic (1.1 mm [0.9 to 1.3 mm]), postoperative (1.0 mm [0.8 to 1.2 mm]), and control knees (1.4 mm [1.1 to 1.6 mm]). ROC analysis demonstrated an optimal threshold value for delta MPFD of 2.0 mm, which had an area under the curve (AUC) of 0.97 (0.94 to 0.99), demonstrating excellent discrimination in identifying knees with patellar instability. No relationships of clinical or morphologic risk factors with delta MPFD were found.

CONCLUSIONS: A delta MPFD of ≥2 mm on the ultrasound-assisted patellar glide test had an AUC of 0.97 for identifying knees with symptomatic patellar instability, indicating excellent discriminatory ability. Additional studies utilizing this method are recommended to standardize and quantify assessments of patellar instability.

LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

PMID:41636736 | DOI:10.2106/JBJS.25.00707

Intimate Partner Violence in a Patient Population with Orthopaedic Trauma: Gender Disparities, Delayed Disclosures, and Poor Clinical Outcomes

J Bone Joint Surg Am. 2026 Feb 4;108(3):212-218. doi: 10.2106/JBJS.25.00407. Epub 2025 Nov 26.

ABSTRACT

BACKGROUND: This prospective cohort study determined the prevalence of intimate partner violence (IPV) across gender groups, investigated timing of disclosures during the standard-of-care follow-up period, and examined if there was an association between IPV and clinical outcomes.

METHODS: This study included 314 patients ≥18 years of age presenting with orthopaedic injuries to the fracture clinics at 2 academic hospitals. Participants were asked about experiences with IPV, return to function, and overall health at each routine clinical follow-up. Cox proportional-hazards regression models were used to explore associations between IPV status and return to work, leisure activities, home responsibilities, and overall functioning.

RESULTS: Of the 528 patients approached, 314 provided consent and completed at least the initial visit. Of these, 184 (58.6%) self-identified as women, 126 (40.1%) identified as men, and 3 (1.0%) self-identified as non-binary. Forty-six percent of women reported lifetime experience of IPV, compared with 35% of men and 100% of gender-diverse participants. A smaller proportion of men who disclosed IPV did so at their first visit compared with women, especially with respect to sexual IPV: 6 men (50.0%) compared with 42 women (79.2%). During follow-up, 16 participants (6.7% of 238 who returned to the clinic at least once), including 8 men, 7 women, and 1 gender-diverse participant, disclosed experiencing IPV during their recovery period. Disclosing IPV at any visit was associated with a 45% lower likelihood of returning to a pre-injury level of function with respect to work (hazard ratio [HR], 0.55 [95% confidence interval (CI), 0.33 to 0.91]; p = 0.021) and a 36% lower likelihood of returning to a pre-injury overall level of functioning (HR, 0.64 [95% CI, 0.46 to 0.90]; p = 0.01).

CONCLUSIONS: Results showed an unacceptably high prevalence of IPV in all genders. Gender differences in timing of disclosure emphasize the need for tailored approaches in clinical settings and repeated opportunities for IPV disclosure. This study emphasizes the hidden nature of IPV among patients with orthopaedic trauma and its effects on their health and recovery.

LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

PMID:41636735 | PMC:PMC12834265 | DOI:10.2106/JBJS.25.00407

Femoral Head Perfusion Varies Widely Following Surgical Reduction for Infantile Developmental Dysplasia of the Hip: Preliminary Findings from a Prospective Study of Contrast-Enhanced Ultrasound

J Bone Joint Surg Am. 2026 Feb 2. doi: 10.2106/JBJS.25.00863. Online ahead of print.

ABSTRACT

BACKGROUND: Surgical hip reduction is an accepted treatment option for infantile developmental dysplasia of the hip (DDH) but may be complicated by the development of osteonecrosis, recently re-termed proximal femoral growth disturbance (PFGD). Since the etiology of PFGD is likely related to compromised vascular supply to the femoral head, the need exists for an intraoperative method of assessing changes in femoral head perfusion prior to irreversible injury. This study sought to utilize contrast-enhanced ultrasound (CEUS) to assess intraoperative changes in perfusion following surgical reduction for infantile DDH, with the ultimate goal of predicting and eventually preventing PFGD.

METHODS: In this prospective study, CEUS was performed before and immediately after surgical reduction and spica casting in infants undergoing surgery for DDH between 4 and 18 months of age. Delta projections were used to quantitatively analyze changes in perfusion, and a statistical analysis was performed to assess the relationships between patient factors, including casting position, and changes in epiphyseal perfusion.

RESULTS: The study population of 32 patients included 34 hips, comprising 30 hips of female patients (88.2%) and 4 hips of male patients (11.8%), with a mean age and standard deviation of 9.3 ± 3.3 months. A lower perfusion index following surgical reduction (p = 0.003) was seen in the majority (79.4%) of hips. In the remaining hips, a higher perfusion index was observed following reduction (p = 0.03). The greatest significant decreases in perfusion index were observed in the central region of the femoral head epiphysis (p = 0.002), followed by the peripheral region of the femoral head epiphysis (p = 0.03). Axial abduction was correlated with a post-reduction decrease in perfusion index (r = 0.35; p = 0.04). There was a moderately positive correlation between body mass index (BMI) and a post-reduction change in perfusion index (r = 0.45; p = 0.01).

CONCLUSIONS: There was wide variation in post-reduction changes in femoral head perfusion after surgical hip reduction and spica casting for infantile DDH, with a gradient of change across the regions of the femoral head. In addition, BMI and in-cast hip position seemed to influence perfusion changes. With continued analysis of these relationships and longer follow-up from our ongoing prospective investigation, we aim to identify the risk factors for PFGD development.

LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

PMID:41628265 | DOI:10.2106/JBJS.25.00863

Substantial Clinical Benefit After Total Knee Arthroplasty Has Been Set Too High: An Analysis of the American Joint Replacement Registry

J Bone Joint Surg Am. 2026 Jan 29. doi: 10.2106/JBJS.25.00952. Online ahead of print.

ABSTRACT

BACKGROUND: The U.S. Centers for Medicare & Medicaid Services (CMS) has set the substantial clinical benefit (SCB) for the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) after primary total knee arthroplasty (TKA) at 20 points. We aimed to determine the percentages of patients who achieved the minimal clinically important difference (MCID) and the SCB for KOOS-JR at 1 year following TKA and to evaluate factors associated with benchmark achievement.

METHODS: We queried the American Joint Replacement Registry (AJRR) and screened 1,284,404 primary TKA cases performed from 2018 to 2023. We determined attainment of the KOOS-JR distribution-based MCID (7.5), anchor-based MCID (14), and SCB (20) at 12 months by each patient. Associations of covariates with the achievement of the MCIDs and the SCB were evaluated using a generalized linear model for binary outcomes that accounted for clustering within institutions. Unadjusted and adjusted odds ratios (ORs) for the outcomes of interest with 95% confidence intervals (CIs) were reported. Covariates included the preoperative KOOS-JR, sex, race or ethnicity, body mass index (BMI), Charlson Comorbidity Index (CCI), fixation type, use of technology, year of the procedure, region, institution type, teaching status, and number of beds.

RESULTS: Linked scores were recorded by 64,773 patients. The mean patient age was 68.35 ± 8.60 years, 61.29% of patients were female, and 83.52% of patients were non-Hispanic White. The KOOS-JR threshold achievement rate was 86.8% for the calculated distribution-based MCID, 76.5% for the anchor-based MCID, and 65.7% for the SCB. Patients with higher preoperative scores (adjusted OR, 0.93 [95% CI, 0.93 to 0.93]; p < 0.001), Asian patients (adjusted OR, 0.59 [95% CI, 0.46 to 0.74]; p < 0.001), Black patients (adjusted OR, 0.55 [95% CI, 0.49 to 0.62]; p < 0.001), Hispanic patients (adjusted OR, 0.71 [95% CI, 0.51 to 0.99]; p = 0.042), non-Hispanic patients of other races (adjusted OR, 0.84 [95% CI, 0.74 to 0.95]; p = 0.007), male patients (adjusted OR, 0.89 [95% CI, 0.85 to 0.94]; p < 0.001), and patients with higher BMI (adjusted OR, 0.93 [95% CI, 0.87 to 0.99]; p = 0.025) showed lower odds of achieving the SCB. A CCI of ≥5 was additionally found to be associated with lower odds of achieving the distribution-based MCID (adjusted OR, 0.89 [95% CI, 0.79 to 0.99]; p = 0.032) and anchor-based MCID (adjusted OR, 0.89 [95% CI, 0.81 to 0.97]; p = 0.012).

CONCLUSIONS: The CMS relatively arbitrarily defined the SCB at a value that is too high for an operation that routinely yields >80% patient satisfaction.

LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

PMID:41610198 | DOI:10.2106/JBJS.25.00952

Cefazolin and the R1 Side Chain: Why Patients with a Cephalosporin Allergy Can Be Safely Given Cefazolin While Undergoing Joint Arthroplasty

J Bone Joint Surg Am. 2026 Jan 27. doi: 10.2106/JBJS.25.01349. Online ahead of print.

ABSTRACT

BACKGROUND: Cefazolin, a first-generation cephalosporin, is the standard antibiotic for perioperative prophylaxis in patients undergoing hip or knee arthroplasty. Research has demonstrated significantly higher periprosthetic joint infection (PJI) rates when non-cefazolin antibiotics are used for prophylaxis. Notably, cefazolin contains an R1 side chain that has not shown cross-reactivity with other cephalosporins. However, in patients with a reported cephalosporin allergy, there is often uncertainty about the optimal antibiotic choice. This study aimed to determine the safety of perioperative cefazolin in patients with a documented cephalosporin allergy undergoing joint arthroplasty.

METHODS: We reviewed the records of 1,268 patients who had a documented cephalosporin allergy and underwent total hip or knee arthroplasty at a high-volume academic center from 2016 to 2024. We compared patients who received cefazolin despite a cephalosporin allergy (n = 482) and patients who received an alternative antibiotic prophylaxis (n = 786). The primary outcome was the incidence of immunoglobulin E (IgE)-mediated allergic reactions or "severe" Type-IV delayed hypersensitivity reactions with end organ dysfunction within 72 hours postoperatively. The secondary outcomes included 90-day rates of complications including PJI, Clostridioides difficile infections, adverse events related to the antibiotic, and readmission.

RESULTS: The incidence of an allergic reaction in patients with an allergy to cephalosporin who received cefazolin was 0.0% (0 of 482) compared with 0.51% (4 of 786) in patients who received an alternative antibiotic prophylaxis (p = 0.30). There were no significant differences in the rates of PJI after primary arthroplasty (0.21% compared with 0.26%; p = 0.83), C. difficile infection (0.0% compared with 0.0%), or readmission within 90 days (3.95% compared with 4.33%; p = 0.75). One patient who received cefazolin experienced mild, self-limited urethral irritation. Five patients receiving alternative antibiotics experienced antibiotic-related adverse events, including skin reactions, gastrointestinal distress, pancreatitis, and headache.

CONCLUSIONS: In this cohort of patients undergoing joint arthroplasty, cefazolin administration in patients with a cephalosporin allergy was associated with a 0.0% incidence of IgE-mediated or severe Type-IV allergic reactions.

LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

PMID:41592154 | DOI:10.2106/JBJS.25.01349

Sex-Based Differences in Cell Types and Gene Expression within the Anterior Cruciate Ligament

J Bone Joint Surg Am. 2026 Jan 26. doi: 10.2106/JBJS.25.00860. Online ahead of print.

ABSTRACT

BACKGROUND: Sex-based disparities remain a major challenge in musculoskeletal medicine. Women and men experience different anterior cruciate ligament (ACL) injury rates and severity, but the causes remain unclear. We hypothesized that cellular differences in human progenitor cells contribute to the higher ACL tear risk observed in females.

METHODS: ACL samples were collected from 4 male and 5 female patients undergoing ACL reconstruction surgery. Live cells were collected through flow cytometry and sent for single-cell RNA sequencing. Significantly greater expression in either sex relative to the other was defined as a >25% increase in expression level (log2 fold change > 0.32) and p < 0.05). Subpopulation characterization was performed with immunofluorescence on tissue sections.

RESULTS: We discovered sex-based differences in all of the native cell types within the ACL. In particular, fibroblast progenitor-like (TPPP3+) cells from female patients expressed genes associated with dysregulation and degradation of collagen more highly than progenitor cells from male patients.

CONCLUSIONS: These results highlight a ligament progenitor population with a sex-dependent gene expression profile. This work suggests that sex-based differences in stem cell populations may drive differential injury rates and outcomes between male and female patients with musculoskeletal injuries.

CLINICAL RELEVANCE: The differential gene expression among TPPP3+ progenitor-like cells provides a possible target population for studying ligamentous injury and regeneration. Differential expression of collagen and extracellular matrix-related genes provides evidence of specific genes that could be therapeutically targeted to strengthen the ACL and reduce the risk of rupture, particularly in female athletes.

PMID:41587266 | DOI:10.2106/JBJS.25.00860

The Cost-Effectiveness of Enoxaparin Compared with Aspirin for Thromboprophylaxis in Patients with Orthopaedic Trauma

J Bone Joint Surg Am. 2026 Jan 26. doi: 10.2106/JBJS.25.00681. Online ahead of print.

ABSTRACT

BACKGROUND: Although clinical guidelines endorse enoxaparin for the prevention of venous thromboembolism in patients with orthopaedic trauma, recent evidence from a large clinical trial has demonstrated that aspirin provides comparable protection against death and pulmonary embolism. This study evaluated the cost-effectiveness of thromboprophylaxis with enoxaparin compared with that with aspirin in patients with orthopaedic trauma from the perspective of the U.S. health-care system.

METHODS: The study modeled a hypothetical cohort of adult patients with an operatively treated extremity, pelvic, or acetabular fracture based on data from a recent clinical trial and national databases. We used a decision analysis model to compare 30 mg of enoxaparin with 81 mg of aspirin, administered twice daily in-hospital and prescribed for 21 days after discharge. Health-care costs and quality-adjusted life-years (QALYs) within 1 year after the injury derived from published research and publicly available cost data were based on potential disease states, including death or a combination of pulmonary embolism, proximal deep vein thrombosis, distal deep vein thrombosis, or a bleeding complication. We assessed cost-effectiveness compared with a willingness-to-pay threshold of $150,000 per QALY.

RESULTS: Our model estimated that the 1-year health-care costs among patients prescribed enoxaparin were $35,301, producing 0.6705 QALYs. Aspirin was associated with $35,067 in 1-year health-care costs and 0.6701 QALYs. The overall health-care costs were $234 higher with enoxaparin but yielded only a 0.0004 improvement in QALYs, for an incremental cost-effectiveness ratio for enoxaparin of $635,340 per QALY, indicating that enoxaparin is not cost-effective compared with aspirin. In a sensitivity analysis, the probability of enoxaparin thromboprophylaxis being cost-effective compared with aspirin was 9.8% in 10,000 iterations.

CONCLUSIONS: The findings suggest that enoxaparin is not cost-effective relative to aspirin for thromboprophylaxis in patients with orthopaedic trauma. The results support consideration of aspirin as a preferred agent in future guidelines, especially given the consistent patient preference for its oral administration.

LEVEL OF EVIDENCE: Economic and Decision Analysis Level I. See Instructions for Authors for a complete description of levels of evidence.

PMID:41587264 | DOI:10.2106/JBJS.25.00681

Autoclaving Effectively Sterilizes Contaminated Retained Cement in Orthopaedic Surgical Trays

J Bone Joint Surg Am. 2026 Jan 23. doi: 10.2106/JBJS.25.00655. Online ahead of print.

ABSTRACT

BACKGROUND: Retained polymethylmethacrylate (PMMA) in surgical instrument trays and on instruments is becoming more common and is a disquieting situation for the arthroplasty operating room team. Although retained debris may be sterile after autoclaving, previous studies have not specifically investigated bacterial viability on retained PMMA. This study determined whether heavily contaminated PMMA surfaces and instruments covered in PMMA could be effectively sterilized by clinically utilized autoclaving protocols.

METHODS: Mature methicillin-susceptible Staphylococcus aureus (MSSA) and Escherichia coli biofilms were grown on PMMA coupons with a smooth surface (n = 5 per condition) or with deep crevices (n = 5 per condition) and on threaded screws, which were inserted into polymerizing PMMA (n = 5 per condition). PMMA coupons and PMMA-covered screws were subjected to 3 autoclave sterilization protocols. Colony-forming unit (CFU) counts and adenosine triphosphate (ATP) levels were measured to detect viable bacteria. Scanning electron microscope (SEM) images were obtained to determine whether biofilm was present.

RESULTS: Non-autoclaved PMMA surfaces were heavily contaminated, with values of 4.1 ± 2.3 × 106 CFUs/mL for S. aureus and 2.4 ± 1.2 × 106 CFUs/mL for E. coli. ATP levels of 3,230 ± 1,297 relative light units (RLU) for S. aureus and 1,006 ± 602 RLU for E. coli were observed. Crevices and screws were also heavily contaminated. Following autoclaving, CFUs/mL counts of <10 and RLU levels of <5 (beneath the hygienic threshold for cleanliness) were recorded on all PMMA surfaces, crevices, and screws. SEM confirmed that the biofilm structures remained intact, but they did not contain viable bacteria.

CONCLUSIONS: PMMA and PMMA-covered instruments contaminated with gram-positive or gram-negative biofilms are effectively sterilized using clinical autoclaving protocols.

CLINICAL RELEVANCE: Retained PMMA and PMMA-covered surgical instruments that undergo a clinical autoclaving protocol do not carry viable bacteria.

PMID:41576107 | DOI:10.2106/JBJS.25.00655

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