Purpose: The purposes of the present study were to assess the levels of prosthetic constraint chosen during revision total knee arthroplasty (TKA) and to identify factors influencing the choice of a constrained prosthesis.
Methods: We retrospectively reviewed data on 274 revision TKAs. The mean follow-up period after revision TKA was 7.2 years. The femorotibial angle (FTA), joint line height (JLH), and Insall-Salvati ratio (ISR) were radiographically evaluated. Factors affecting the extent of constraint chosen were evaluated in terms of age, gender, body mass index, primary diagnosis, the cause of revision TKA, the Anderson Orthopedic Research Institute (AORI) classification, and changes in the JLH and ISR.
Results: Totals of 247 (90.1%), 11 (4.0%), and 9 (3.4%) knees received posteriorly stabilized prostheses, constrained condylar knees, and rotating hinge prostheses, respectively. On multivariate analysis, the cause of revision TKA including loosening and instability and the changes in the JLH and ISR affected independently the choice of a constrained prosthesis.
Conclusions: The frequency of implantation of constrained prostheses was 7.4% in the present study. Consideration of various factors including the cause of revision TKA and changes in the JLH and ISR will aid the TKA surgeon in selecting prostheses with appropriate constraints when performing revision TKAs.
Keywords: Arthroplasty; Constraint; Knee; Revision.