CT EVALUATION OF FEMORAL COMPONENT ROTATIONAL ALIGNMENT ICLINICALLY PROBLEMATIC TKA

Abstract

Malpositioning of prosthetic components in TKA may cause clinical relevant complications. This study focuses on a variety of TKA problems that were related to femoral component internal malrotation.

Inclusion criteria in this study were all TKA seen at one-year follow-up with a moderate or poor clinical outcome using the Knee Society Score. Reduced mobility, pain, and patella problems were most frequent in this group. Infection, trauma, or wound problems were exclusion criteria. Two different mobile bearing knee systems were utilised in one large centre; LCS (DePuy Int, Leeds, UK) and MBK (Zimmer, Warsaw, USA). From more than 200 LCS and 70 MBK prostheses 27 cases entered the study, all of which underwent spiral CT investigation for evaluation of femoral component rotational alignment.

There was an increased incidence of femoral component internal rotation in this group with poor outcome. Mean internal rotation was 4.2 degrees (0 to 8) in relation to the transepicondylar axis.

Evaluation of femoral component rotational alignment in TKA has recently gained increased attention. Particularly internal malrotation does often lead to flexion instability, poor biomechanics, and patellofemoral tracking problems with lateral subluxation. It is also associated with painful and stiff knees as recently reported (AAOS 2002, Dallas, USA). In this study early postoperative complications in TKA were also associated with femoral component internal malrotation. We, therefore, recommend CT evaluation of component alignment in clinically doubtful knees. Cases that present with internal malrotation should be considered for revision surgery with the view to revise the femoral and/or tibial component.