Outcomes of primary and revision total knee arthroplasty with constrained condylar knee prosthesis: A retrospective review

Abstract

Background: The constrained condylar knee (CCK) implants are becoming more frequently used but the long-term outcomes are inadequately reported. A retrospective review of complex primary and revision total knee arthroplasty (TKA) with use of Legacy Constrained Condylar Knee prosthesis (LCCK; Zimmer) was performed to evaluate the functional and radiological outcomes, identify complications, and ascertain prosthesis survival. Methods: A cohort of 54 primary TKA and 37 revision TKA cases were performed between December 2002 and March 2021 using the second-generation CCK prosthesis. The cases without using the constrained insert were excluded. Functional outcome comparison includes flexion and extension range of movement (ROM), Knee Society knee score (KSKS), function score (KSFS) and complications. Radiological outcome comparison includes tibiofemoral angle, hip-knee-ankle (HKA) angle and prosthesis components alignment. Survival analysis was performed using revision surgery for any reason as censoring criteria. Results: The mean follow-up duration was 4.8 years (1.0–9.9 years) in primary TKA group and 6.2 years (1.0–18.6 years) in revision TKA group. The mean KSKS improved from 40.5 to 86.6 in primary TKA group and from 58.8 to 79.6 in revision TKA group. The mean KSFS improved from 41.8 to 58.9 in primary TKA group and from 34.1 to 58.2 in revision TKA group. The overall complication rate was 7.5% in primary TKA group and 35.1% in revision TKA group. Aseptic loosening was found in 6 cases and periprosthetic joint infection was found in 5 cases. Kaplan-Meier survivorship analysis estimated the overall mean survival was 17.9 years and 10-year survival rate was 93%. Conclusions: Complex primary and revision TKA with use of LCCK prosthesis yielded significant reproducible improvement of clinical outcomes. The failure rate was low in primary TKA but relatively higher in revision cases.