Journal of Bone and Joint Surgery, American Volume最新文献

Background: Rotator cuff (RC) tears are common shoulder injuries that cause pain, dysfunction, and abnormal humeral head translation. Balanced force couples in the transverse and coronal planes help to maintain normal glenohumeral mechanics. Although clinical and biomechanical studies have suggested that compensatory activation of residual RC muscles preserves function, the contribution of individual RC subregions to glenohumeral contact mechanics and humeral head translations across progressively increasing tear sizes remains unclear.

Methods: Eight fresh-frozen male cadaveric shoulders (mean age, 56 years; 6 Caucasian; 2 Black) were dissected to isolate RC muscle subregions, and 4 progressive RC tear models were created: Tear I (supraspinatus [SSP] + superior region of the infraspinatus [ISP]), Tear II (SSP + complete ISP), Tear III (SSP + ISP + superior one-third of the subscapularis [SSC]), and Tear IV (SSP + ISP + superior one-third of the SSC + coracohumeral ligament). Each model underwent 3 loading conditions: loaded (as in the intact state), unloaded (i.e., unloading of the torn regions), and compensatory (i.e., increased loading of the remaining subregions). Humeral head translations and glenohumeral contact force, area, and pressure were measured at 10° of abduction with neutral rotation.

Results: Unloaded conditions significantly increased superior and posterior humeral head translations and reduced contact force and area in most models, particularly in Tears III and IV. Compensatory loading by residual RC subregions reduced superior translation by 34% to 44% and posterior translation by 60% to 68%, restoring the humeral head center to within 0.1 to 1.7 mm of its position in the intact condition. Contact forces and areas partially recovered under compensatory loading; however, contact pressure remained elevated in the largest tear model.

Conclusions: Residual RC subregions can partially restore humeral head centering and glenohumeral contact mechanics in progressive RC tears. However, compensation is limited in advanced tear states, highlighting the potential need for surgical intervention to restore force-couple integrity in the transverse plane.

Clinical relevance: These findings support targeted strengthening of the posterior cuff in patients with partial or early-stage massive RC tears to help maintain joint congruency, minimize abnormal glenohumeral contact mechanics and humeral head translation, and potentially delay the progression to cuff tear arthropathy. Surgical repair, particularly of the SSC, may be required in advanced tears to fully restore force coupling and load distribution.

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.

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.

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.