Background Although the hip is generally considered a stable joint, certain morphological configurations—such as acetabular dysplasia or abnormal femoral torsion—can predispose it to instability. Gluteus minimus indentation, a lateral femoral head morphologic finding, has been described in patients with cerebral palsy and severe dysplasia; however, whether it occurs in other instability-related hip morphologies and whether it has clinical relevance remains unclear. Questions/purposes (1) Did a higher percentage of patients with hip dysplasia (defined as a lateral center-edge angle [LCEA] < 22°) have gluteus minimus indentation than patients without dysplasia? (2) Was there an association between gluteus minimus indentation and acetabular or femoral radiological parameters? (3) Were there differences in three-dimensional (3D) cartilage and labral parameters between hips with and without gluteus minimus indentation? Methods Between November 2019 and December 2024, 761 hips (703 patients) underwent MR arthrography for nontraumatic hip pain at our institution and were included in this retrospective, single-center study. MR arthrography was ordered for patients whose hip pain had not improved after at least 3 months of conservative treatment and who were being considered for hip preservation surgery. We excluded 47% (357 of 761) of hips for previous hip surgery, trauma, avascular necrosis, advanced osteoarthritis, tumors, childhood conditions, or inadequate imaging, and a further 2% (12 of 761) to retain one hip per patient, leaving 392 hips for analysis. The included patients had a mean ± SD age of 32 ± 10 years, and 58% (229 of 392) of patients were females. In all, 18% (69 of 392) had dysplasia (LCEA < 22°) and 59% (231 of 392) had increased femoral torsion (> 25°). No patients had cerebral palsy. Gluteus minimus indentation and its topographic distribution, reported using a clockface system, were assessed on radial MR sequences. Radiographic parameters were measured on AP pelvis radiographs. Three-dimensional models of the acetabular cartilage and labrum were generated from an MRI sequence (magnetization-prepared 2 rapid gradient-echo) that produces high-contrast images in which cartilage and the labrum can be clearly distinguished. The models were created using a previously validated deep-learning algorithm trained to outline these structures. In the validation study, agreement with manual segmentation was excellent. Results Gluteus minimus indentation was present in 7% (29 of 392) of hips. A higher percentage of patients with hip dysplasia had gluteus minimus indentation than patients without dysplasia (22% [15 of 69] versus 4% [14 of 323]; p < 0.01). After controlling for acetabular version, retroversion index, caput-collum-diaphyseal angle, age, and sex, each 5° decrease in LCEA was associated with a 1.5 times higher odds of gluteus minimus indentation (95% confidence interval (CI) 1.2 to 1.9; p < 0.01), and each 5° increase in femoral torsion was associated with a 1.3 times higher odds (95% CI 1.1 to 1.6; p < 0.01) of gluteus minimus indentation. In dysplastic hips, defined as a LCEA < 22°, and hips with increased femoral torsion (> 25°), those with gluteus minimus indentation had a smaller relative cartilage surface area, a greater labral volume, and a greater labral contribution to the joint surface. These differences persisted after accounting for LCEA and for femoral torsion, respectively. Conclusion Gluteus minimus indentation was most common in dysplastic hips, although it also occurred in hips with increased femoral torsion and normal coverage. Its association with a smaller cartilage surface area and greater labral contribution suggests that it may be a marker of instability that warrants closer evaluation. The frequency and clinical significance of gluteus minimus indentation in asymptomatic hips are unknown, and the presence of gluteus minimus indentation should not influence treatment until its relevance to prognosis, natural history, or treatment response is established. Level of Evidence Level IV, prognostic study.
BACKGROUND:Studies of new surgical techniques usually report the result without separating outcomes by factors such as surgeon volume, experience, or practice setting. But those same factors shape the result, so a technique that benefits patients in the hands of the surgeons who reported it might actually harm patients in the hands of surgeons who meaningfully differ. Published outcomes describe the surgeons and conditions that produced them, but there is little to guide surgeons considering a new approach beyond a nonspecific sense of risk versus reward. QUESTIONS/PURPOSES:(1) Does the decision to adopt a surgical technique reverse depending on surgeon-level variables, even when the underlying evidence is the same? (2) Can a formal model identify the conditions under which adoption produces net harm to a surgeon's patients? METHODS:A volume-stratified decision-analytic model was developed that calculates a surgeon-specific break-even horizon, the point at which cumulative benefit first exceeds cumulative learning-curve harm. The model was applied to direct anterior approach versus posterior approach hemiarthroplasty, with parameter values drawn from the published direct anterior approach and posterior approach evidence and stratified by annual case volume. The model integrates three parameters: the number needed to treat (NNT) for a single claimed benefit of the new technique; a learning-curve decay constant (λ) derived from cumulative sum (CUSUM) analyses, where a higher value means faster learning (λ = 0.07 implies proficiency in roughly 40 cases, λ = 0.03 in roughly 100); and a complication severity weight of harm (Wh) anchored to the risk of reoperation. The benefit is granted favorably and weighed against learning-curve harm assigned to the new approach alone, ignoring the established approach's advantages and the cost of switching; every simplification therefore favors adoption. An interactive tool lets readers enter their own values. RESULTS:The decision to adopt a new surgical technique depended heavily on surgeon-specific factors, chiefly annual case volume. The same published evidence pointed toward adoption for a higher-volume surgeon and against it for a lower-volume one. Three parameter scenarios were tested across three volume tiers (8, 20, and 50 patients per year). Under innovation-favorable parameters (NNT = 50, λ = 0.07, Wh = 1), all three tiers reached breakeven within 4 years, and 20-year cumulative utility was positive throughout (2.5 to 19.3). Under default parameters (NNT = 100, λ = 0.05, Wh = 3), breakeven ranged from 5 years 10 months at 50 patients per year to beyond 20 years at the lowest tier (20-year utility 7.1 to -1.3), and the 8-patient-per-year surgeon never reached breakeven. Under innovation-unfavorable parameters (NNT = 140, λ = 0.04, Wh = 4), only the 50-patient surgeon reached breakeven, at 13 years 9 months (2.2); the lower tiers ended in net harm (-2.0 and -3.7). In every scenario, the higher-volume surgeon did better. What shifted with the parameters was only whether adoption was favorable at all: uniformly so under optimistic assumptions, volume-dependent at default values, and favorable only at the highest volume under unfavorable ones. CONCLUSION:Whether a newly reported technique helps or harms depends heavily on how often the operating surgeon performs the procedure and how much relevant experience they bring, factors that the published studies rarely report. This holds for any innovation that offers a modest benefit and carries a learning curve, not only the approach examined here. CLINICAL RELEVANCE:Published innovation studies report outcomes from one set of surgeons, at particular volumes and levels of experience, but are often read as if they applied to everyone. In deciding whether to adopt a new technique, surgeons should weigh their own case volume and relevant experience alongside the published result, recognizing that a beneficial-sounding result may not reach breakeven at lower volume within a clinically meaningful period. Future studies could extend this work by reporting outcomes stratified by surgeon volume and experience so that readers can locate themselves rather than assume that a published result transfers. An interactive version of the model, which lets readers enter their own volume and experience, is available at https://rcpmodel.netlify.app.
BACKGROUND:Despite advances in imaging, nonoperative management, immunotherapy, and surgery over the last 15 years, sizable improvements in survival for patients with spinal metastases have not been observed. Older studies may no longer be accurate in light of rapid technological improvements. The performance of scoring utilities, such as the Skeletal Oncology Research Group (SORG) nomogram and the New England Spinal Metastasis Score (NESMS), has also not been investigated beyond the first year of treatment. QUESTIONS/PURPOSES:(1) What was the 5-year survival of patients who presented with spinal metastases and were treated with or without surgery according to contemporary indications, stratified by tumor type? (2) How effective were the SORG and NESMS at prognosticating survival up to 5 years after presentation? METHODS:We used our healthcare system's registry to identify patients treated operatively and nonoperatively for spinal metastatic disease (full surveillance inclusive of follow-up from January 1, 2017 to December 31, 2025). Data included in this study were drawn from two large, tertiary academic hospitals in a single major city, as well as from two local affiliate community hospitals. This study environment allowed for capturing a broad sample of tumor and treatment types, which is representative of the complex care associated with spinal metastatic disease. Query of the registry identified 997 patients; 71 patients were excluded because their initial presentation was < 5 years from the final data date; they were therefore ineligible for 5-year evaluation. Those whose initial presentation was < 5 years from study initiation, but had died, were maintained. One percent of patients (13 of 926) were eligible for 5-year follow-up but had an unknown vital status. Missing data were uncommon, with no variable having > 1% missingness. Sixty percent (551) of patients were treated with surgery. Overall, the surgical and nonoperative cohorts were comparable regarding demographic and clinical characteristics. Patients treated with surgery were slightly older than those treated nonoperatively (62 years versus 59 years; p < 0.01). The nonoperative cohort had a female predominance, whereas the surgical cohort did not (56% versus 43%; p < 0.001). Both cohorts had a median CCI score of 8 (p = 0.7). There were no differences in the use of immunotherapy between those treated with surgery (29%) and those treated with nonoperative care (27%; p = 0.6). We evaluated survival over the course of 5 years after presentation. In this registry, death is captured through a combination of medical record documentation as well as linkage to external state and federal sources. We performed multivariable Cox proportional hazards regression analysis for 5-year survival using each spinal metastasis prognostic score. The SORG is a prognostic score from 0 to 100 that represents the calculated probability of survival. NESMS ranges from 0 to 3, with higher scores representing a more favorable clinical state. Separate models were generated using SORG and NESMS as the primary explanatory variable, respectively. Both models adjusted for age, sex, race, comorbidity burden, immunotherapy, and surgical treatment. RESULTS:At the 5-year time point, the Kaplan-Meier survival estimate was 8.9% (95% confidence interval [CI] 7.2% to 10.9%). Patients with lung cancer demonstrated the lowest survival rate among the discrete tumor types at every time point. When accounting for age, sex, race, comorbidities, immunotherapy, and treatment type, the SORG score was associated with survival (HR 0.98 [95% CI 0.98 to 0.99]; p < 0.001), meaning that each single-point increase in SORG score was associated with a 2% decreased likelihood of mortality. When controlling for the same variables, the NESMS was also associated with 5-year survival (HR 0.61 [95% CI 0.56 to 0.66]; p < 0.001), meaning that each 1-point increase in SORG score was associated with 40% reduction in mortality. CONCLUSION:We present long-term survival for patients with spinal metastases in the modern period of spine oncology care, stratified by primary cancer type. Although mortality rates over time remain high, our study is the first to show that approximately 10% of patients will survive 5 years or longer. These data can aid in patient counseling as well as surgical decision-making. Understanding the 5-year survival forecast for patients with spinal metastases will help physicians tailor treatment decisions and can help surgeons prioritize minimizing surgical morbidity with shorter, simpler operations, when possible. Both the SORG and NESMS can be used to support long-term estimations regarding survival. LEVEL OF EVIDENCE:Level III, therapeutic study.
Background Pediatric acute hematogenous osteomyelitis (PAHO) is a bone infection usually caused by Staphylococcus aureus , where bacteria spread through the bloodstream and colonize bone tissue. In many countries, including New Zealand, most cases of PAHO are attributed to methicillin-susceptible S. aureus (MSSA). Although standard antibiotic therapy is effective in many cases (uncomplicated infections), some are difficult to resolve, leading to a poor clinical outcome (complicated infections). These patients often require intensive care admission, extended antibiotic treatment, and sometimes develop chronic infection. While antibiotic resistance and host factors are well-known contributors, bacterial genetic determinants remain relatively underexplored and likely play a critical role in disease severity and therapeutic response. Questions/purposes (1) Are the MSSA isolates found in children who had complicated infections genetically distinct from those from uncomplicated infections? (2) Is a complicated clinical outcome in PAHO associated with MSSA displaying reduced phenotypic susceptibility to antibiotics or the carriage of known genetic determinants of antimicrobial resistance? (3) Which genes and, in particular, which virulence factors are associated with complicated infections? Methods The study cohort comprised 85 MSSA isolates from 85 patients with PAHO collected at New Zealand’s largest children’s hospital. These isolates were split into two groups: complicated (n = 38, from patients with infections that required intensive care admission or were difficult to resolve with standard antibiotic treatment) and uncomplicated (n = 47, from patients with readily cleared infections). Phenotypic antimicrobial susceptibility testing was performed for all isolates. Whole-genome sequencing was performed for molecular typing, identification of antimicrobial resistance genes, and virulence factor genes. Isolate relatedness was identified using phylogenetic analysis. A genome-wide association study was conducted to identify genetic determinants associated with a complicated outcome. Results MSSA infections in PAHO are caused by a genetically diverse group of isolates, with no clustering of strains between complicated and uncomplicated infections. No differences in the levels of phenotypic susceptibility and presence of beta-lactam resistance genes between complicated and uncomplicated isolates was observed. However, genome-wide association analysis identified several virulence factors associated with complicated outcomes, including Panton-Valentine leukocidin (PVL) genes lukS-PV and lukF-PV (OR 23; q < 0.001), von Willebrand factor-binding protein (vWbp) (OR 13; q = 0.015), and capsular polysaccharide type 8 genes cap8HIJK (OR 11; q = 0.038). The fosfomycin resistance–associated mutation glpT_L27F was also associated with complicated outcomes. Conclusion Our findings suggest that complicated outcomes in MSSA infections in PAHO are associated with specific virulence gene carriage rather than classical antimicrobial resistance mechanisms. In a clinical setting, these findings have the potential to contribute to improved outcomes by molecular detection of high-risk virulence profiles, enabling targeted management in high-risk cases. Future studies could investigate whether biofilm formation and differential virulence factor gene expression contribute to variable clinical outcomes. Level of Evidence Level II, therapeutic study.
