Liner dissociation leading to catastrophic failure of an Oxinium femoral head

Oxinium is an alternative bearing surface designed to emulate the superior wear and scratch properties of ceramic femoral heads in total hip arthroplasty while minimizing the risk for brittle fracturing. However, recent studies have indicated that hip dislocation following total hip arthroplasty may be a risk factor for catastrophic failure of the femoral head. Here, we report on a novel case of a catastrophic Oxinium head and polyethylene liner failure in the absence of previous hip dislocation or trauma and review the probable failure mechanism. This report underscores the need to be vigilant about proper acetabular cup and liner seating, particularly in the setting of Oxinium femoral head use. In the event of Oxinium head failure, metallosis may compromise stabilizing soft tissues including the abductors. Dual-mobility articulation, which was successful in this case, is one option to consider when the risk for chronic redislocation is elevated. Keywords: Liner dissociation, Dual-mobility system, Oxinium, Oxidized zirconium, Total hip arthroplasty, Total hip replacemen

Payer type does not impact patient-reported outcomes after primary total knee arthroplasty

Background: There is a paucity of literature assessing whether payer type has an impact on postoperative patient-reported outcomes (PROs) after total knee arthroplasty (TKA). The aim of this study was to comparatively evaluate TKA PROs among patients with commercial and Medicare insurance. Methods: We conducted a single-center, retrospective review of patients operated between January 2017 and March 2018. Knee Disability and Osteoarthritis Outcome Score Junior (KOOS-Jr) and Veterans RAND 12 Health Survey (VR-12) Physical Component (VR-12 PCS) and Mental Component (VR-12 MCS) PRO scores were collected prospectively at baseline and 12 weeks postoperatively via an electronic patient rehabilitation application. Univariable and multivariable linear regressions were utilized to assess the effects of patient insurance type on PRO. Results: In total, 193 TKA candidates had commercial (n = 91) or Medicare (n = 102) as their primary payer type. Demographic variables including age, gender, body mass index, and race varied significantly between the cohorts (P .05). Furthermore, ΔPRO scores from baseline to 12 weeks were also similar (P > .05). Conclusions: After adjusting for patient-specific variables, PROs are similar at baseline and 12 weeks postoperatively between commercial and Medicare cohorts. For TKA candidates with similar baseline demographics, surgeons can expect similar perioperative PROs regardless of insurance type. Keywords: Insurance, Patient-reported outcomes, Total knee arthroplasty, Medicar