Maintaining posterior stability in total knee arthroplasty (TKA) may be achieved by using a posterior stabilized TKA, retaining and balancing the posterior cruciate ligament (PCL) using a traditional cruciate-retaining design (CR), or by increasing the sagittal plane conformity of the tibial insert. In the latter case, stability is achieved by the addition of an anterior buildup on the tibial polyethylene creating the so-called “anterior stabilized” (AS) design. We hypothesized that using an AS tibial insert would provide similar function and survivorship as compared to using a more traditional CR bearing when the PCL is either recessed or balanced. Between 2004 and 2016, 1,731 modular CR TKAs were implanted in 1,509 patients using the same CR TKA design. The diagnosis was osteoarthritis in 98%. 58% of patients were female. Average age of 64.9 years. Within this group, 868 TKAs (50.1%) had a standard CR tibial bearing (3-degree posterior slope and no posterior lip) implanted (CR-S). 480 TKAs (27.8%) had a lipped CR modular tibial bearing (2.5 mm elevated posterior lip) implanted (CR-L). Starting in 2013, 383 TKAs (22.1%) were implanted with an AS modular tibial bearing (9–11 mm anterior lip and a 5 mm posterior lip). If the PCL was considered non-functional or absent, an AS bearing was placed. If the PCL was considered functional, a standard bearing or lipped bearing was used. Clinical and radiographic analysis was performed according to the Knee Society (KS) grading system. The most recent clinical and radiographic evaluation was used for post-operative analysis. The average follow-up in the entire cohort of TKAs was 5.5 years (range 2 to 14.3 years). Kaplan-Meier analysis was used to determine prosthesis survivorship with failure defined as aseptic loosening of the prosthesis (with or without revision) or tibial insert exchange.Introduction
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Dual-mobility (DM) articulations may be useful for patients at increased risk for instability in primary and revision THA. While DM articulations are becoming increasingly popular, its routine use in primary THA is more uncertain. Even less is known about femoral head penetration in DM designs manufactured with highly cross-linked polyethylene infused with Vitamin E (E-HXLPE). The purpose of this study was to evaluate the early clinical results and femoral head penetration rates of primary THA implanted with DM E-HXLPE. Between 2012 and 2017, 105 primary DM THAs were performed using a one-piece acetabular shell, 28mm ceramic head, coupled with an E-HXLPE outer bearing via a standard posterior approach. Three patients refused follow-up after six months. 102 hips (92 patients) were available for review. The diagnosis was 99% OA. Average age was 65.7 years (33–90 years). 56% of patients were female. The most common femoral head size was 50mm (range, 44–60mm). The average thickness of the E-HXLPE outer bearing was 22.7mm (range, 16–32mm). Patients were followed at two months (baseline radiograph), six months, one, three, five, and seven years. Harris hip scores (HHS), UCLA activity score, and femoral head penetration (Martell method) were obtained at each visit beyond two months. Follow-up averaged 3 years (range, 1–7 years).Introduction
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