Purpose: Stiffness following TKA is devastating and poorly understood. This study was conducted to determine if rotational positioning of tibial and/or femoral components was related to the development of stiffness following TKA. In addition, post-revision rotational alignment was studied to determine if it contributed to improvement.

Method: Patients who presented with stiffness and either a fixed flexion contracture > 15 and/or flexion < 105 degrees were included in the study. 34 revisions were investigated preoperatively by computerized tomography (CT) for rotational evaluation of the components. Clinical and radiographic data were also recorded.

Results: All 34 revisions had some degree of combined internal rotation on the preoperative CT-scan. The net combined angle averaged fourteen point eight degrees of pathologic internal rotation (in excess of the normal eighteen degrees)[1]. The most significant source of internal rotation was the tibial component, with 33 of the 34 patients having internal rotation with a mean pathological (in excess of the normal eighteen degrees) angle of 13.3 degrees (one to 35 degrees). Postoperatively, the combined rotation angle was restored to an average of five point one degrees of external rotation for the eighteen patients with available CT-scans (p < 0.0001). The 34 revised knees were clinically followed for an average of 22 months. The mean preoperative Knee Society knee and function scores were respectively 41.6 and 47.9. The mean preoperative range of motion was 61.4 degrees. Postoperatively, the knee and function scores increased respectively to 77.3 and to 65.7 (p < 0.0045). The mean postoperative range of motion averaged 98.1 degrees (p < 0.0001).

Conclusion: Rotational positioning of the components should be investigated with CT-scan in stiff knees following TKA. Revision surgery of all the components with restoration of an adequate rotational alignment has been shown to improve range of motion, function and pain.