Background and Objectives: The optimal pharmacological strategy to mitigate progressive vertebral collapse during the acute phase of osteoporotic vertebral compression fractures (OVCFs) remains a subject of debate. This initial 3-month window is the most critical period for evaluating the structural stability of the fracture, as the majority of progressive height loss occurs before solid bone union is achieved, directly influencing the decision to continue conservative management or transition to surgical intervention. Materials and Methods: In this retrospective study, 123 patients were allocated to control (n = 26), denosumab (n = 35), teriparatide (n = 30), or romosozumab (n = 32) groups. Treatment choice was non-randomized, driven by clinical pragmatism and patient preference. Serial changes in vertebral compression rate (VCR) and pain (VAS) were analyzed over 3 months using linear mixed models (LMMs) specifically adjusted for baseline imbalances in initial VCR. Results: In the unadjusted analysis, DMAB appeared to show a slower progression of compression compared to the control group. However, after adjusting for the initial VCR, no significant structural benefit was observed in any medication group (p > 0.05), with all groups showing small effect sizes (Cohen’s d < 0.4). In contrast, unstable fracture morphology was identified as the most potent driver of vertebral collapse (β = 2.758, 95% CI: 1.51–4.01, p < 0.001). Clinically, the RM group showed significantly lower overall pain levels throughout the follow-up period compared to the control group (p = 0.014). Conclusions: Short-term osteoporosis medication does not significantly mitigate vertebral collapse during the acute phase of OVCFs. Practically, these findings suggest that unstable fracture morphology and the baseline VCR—reflecting a potential ‘floor effect’ where less initially collapsed vertebrae may undergo more significant progression—are more informative predictors of acute collapse than medication choice. Consequently, early imaging-based risk stratification is crucial to identify patients at high risk for progressive deformity, regardless of their pharmacological regimen.

Background and Clinical Significance: With increasing demand for total knee arthroplasty (TKA), the incidence of post-operative instability has also risen. Although fracture of the polyethylene tibial post in posterior-stabilized (PS) prostheses is relatively uncommon, it should not be overlooked because delayed recognition may lead to severe late sequelae. Case Presentation: Between April 2008 and January 2020, 132 revision TKAs were performed at our institution due to suspected instability with or without component loosening. Among these, three patients were identified as having instability associated with fracture of the polyethylene tibial post in PS implants. All three patients presented late, with a mean interval of 49.66 months (range 34–74) after the index TKA. At presentation, all demonstrated multiplanar global instability, and two showed recurvatum deformity. Pre-operatively, revision surgery was indicated due to progressive global instability. Although tibial post fracture was suspected as a possible underlying cause, the diagnosis could not be definitively established until intraoperative inspection, which confirmed polyethylene tibial post fracture in all cases. Each patient underwent revision TKA using a semi-constrained prosthesis with an increased polyethylene insert height. At final follow-up (12–18 months), all patients achieved complete resolution of clinical instability and demonstrated meaningful improvement in the Hospital for Special Surgery (HSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. Conclusions: Although rare, polyethylene tibial post fracture should be considered in the differential diagnosis of post-operative knee instability following PS TKA. Early recognition may allow management with isolated polyethylene exchange, whereas delayed diagnosis can result in progressive ligamentous insufficiency and global multiplanar instability, ultimately necessitating revision using a semi-constrained implant.