Determining femoral rotational alignment in total knee arthroplasty - Reliability of techniques

Several anatomic axes routinely are used for determining femoral rotational alignment in total knee arthroplasty. The purpose of this study was to det ermine the reliability of these techniques. The transepicondylar axis, ante roposterior axis, and balanced flexion gap tension line were identified rel ative to the posterior condylar axis in 8 fresh frozen cadaver knees by 3 i ndependent observers. The flexion-extension axis was defined in each knee f or comparison. The anteroposterior and balanced tension axes defined most r eliably the flexion-extension axis and best balanced the flexion gap with n o significant interobserver differences. The transepicondylar axis was less predictable and significantly more externally rotated than the anteroposte rior axis (P < .005) and the balanced tension line (P < .00001). Flexion ga p tensioning may offer superior reliability because of its independence of obscured or distorted bone landmarks.