[Pathological findings and therapy for anterior knee pain following total knee arthroplasty].

INTRODUCTION: An incidence of 10 % for anterior knee pain following total knee arthroplasty has been published. Often several factors can be found leading to functional deficits following total knee arthroplasty. The aim of our study on a consecutive series of revised total knee arthroplasties due to anterior knee pain is to show the pathological findings and their therapy.

PATIENTS AND METHOD: Between January 1, 2006 and March 31, 2007 13 revisions including 2 men and 11 women due to anterior knee pain following total knee arthroplasty were performed. Mean duration between index operation and revision was 13.2 months.

RESULTS: In all cases lateralisation of the patella often accompanied by hypertrophy of the lateral facet could be detected. In one case severe medial and lateral instability of the collateral ligaments was found. A meniscoid could be described in 2 cases. In one additional case malpositioning of the tibial component could be found. After resection of the hypertrophic lateral patellar facet and lateral release and therapy for additional pathologies all patients were free of complaints after a mean follow-up of 9 months.

CONCLUSION: For avoiding anterior knee pain following total knee arthroplasty an exact positioning of both the femoral and the tibial component is essential. Additionally stable collateral ligaments and exact gliding of the patella by means of the "no thumb sign" should be achieved, too. During the operation hyperextension of 5 degrees is essential. If, intraoperatively, a hypertrophic lateral patellar facet is detected we recommend its resection.