Survivorship and Functional Outcomes of Condylar-Stabilized Total Knee Arthroplasty Designs: An Analysis of the American Joint Replacement Registry.

Abstract

The popularity of condylar-stabilized (CS) designs in primary total knee arthroplasty (TKA) is increasing. However, CS designs lack consistent classification and registry data examining survivorship. This study assessed revision risk and patient-reported outcome measures (PROMs) among CS designs and compared them to cruciate-retaining (CR) and posterior-stabilized (PS) designs using the American Joint Replacement Registry (AJRR). The AJRR was queried for all patients 65 years of age and older undergoing elective primary TKA with CR (n = 111,622), PS (n = 282,487), or CS (n = 162,648) designs between January 2012 and December 2021, with a minimum two-year follow-up. The CS designs were classified as anterior-stabilized (n = 96,897), ultracongruent (n = 29,427), medial-stabilized (n = 21,555), medial-pivot (n = 11,171), and lateral-stabilized (n = 3,598). Outcomes analyzed included all-cause revision, revision for infection, aseptic revision, and patient-reported outcome measures (PROMs). Compared to the CR designs, medial-stabilized designs demonstrated lower all-cause adjusted hazard ratio (aHR) = 0.77, confidence interval (CI): 0.66 to 0.90, P < 0.001) and aseptic revision risk (aHR = 0.75, CI: 0.62 to 0.90, P = 0.002), lateral-stabilized designs had higher all-cause (aHR = 1.62, CI: 1.29 to 2.03, P < 0.001) and aseptic revision risk (aHR = 1.53, CI: 1.22 to 1.91, P < 0.001), and medial-pivot designs had higher all-cause (aHR = 1.23, CI: 1.02 to 1.48, P = 0.028) revision risk. There were no other differences when comparing the CR designs to the CS design subgroups. The PS designs had a higher risk of aseptic failure (aHR = 1.09, CI: 1.01 to 1.17, P < 0.001) compared to the CS designs, but there was no difference between the CR and the CS designs. There was no significant difference in the likelihood of achieving the minimal clinically important difference (MCID) in PROMs between groups at one-year postoperatively. The CS designs demonstrate improved survivorship compared to the PS designs and have comparable revision risk to the CR designs. Among the CS designs, medial-stabilized designs demonstrate decreased revision risk, while lateral-stabilized and medial-pivot designs have a higher risk of revision. There was no difference in achieving MCID in PROMs among designs.