JBJS

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

Pages