[Revision prosthetic of the knee joint. The influence of a navigation system on the alignment and reconstruction of the joint line].

Recognizing the rising number of primary total knee arthroplasties (TKA) over the last decade, one may assume an increasing number for revisions after a certain time delay. Studies showing a rate of only 78% satisfied patients provide a hint that there is still room for improvement. Therefore, it seemed worthwhile to evaluate the benefits of the computer assisted technique in revision TKA and compare the alignment results with the conventional technique. In a prospective study, 120 patients were operated for revision TKA using either the Vector-Vision navigation system (n=60) or the conventional technique (n=60). The axial limb alignment was evaluated on standardized pre- and postoperative full length weight-bearing radiographs and the variation of the joint line was determined by the method of Figgie from 1986.A precise reconstruction of the mechanical limb axis was achieved in 57/60 Patients (95%) in the computer assisted group and in 48/60 (80%) in the conventional group. A reconstruction of the joint line with a variation of less then 4 mm was achieved in 47/60 (78%) in the computer assisted and in 33/60 (55%) in the conventional group. Revision TKA remains a challenging procedure for the surgeon. Modern navigation systems offer additional information intraoperatively and might therefore simplify the procedure. In particular, the adjustment of the extension and flexion gap and the reconstruction of the joint line the results were superior. Furthermore, the use of a CT-free navigation system provides a significant improvement of prosthesis and leg alignment in revision TKA.