TOTAL KNEE ARTHROPLASTY DISLOCATION: INCIDENCE, ETIOLOGY, AND MANAGEMENT

Abstract

Introduction: Dislocation following total knee arthroplasty (TKA) is an unusual but dramatic post-operative complication. Previously reports involve only a few isolated cases. This study retrospectively analyzed the incidence, associated factors and treatment of dislocation following TKA.

Method: All cases of TKA dislocation since 1970, when the first TKA was done at our institution, were identified from our institutional total joint registry (31.000 TKA). The medical history and X-ray were reviewed on all cases with this diagnosis. The 58 cases identified were reviewed with particular attention to associated factors that might contribute to this problem.

Results: The overall incidence of TKA dislocation was 1.87 per 1.000 arthroplasties, with a rate of 0.93 and 6.61 for primary and revision TKA respectively. The dislocations occurred at the mean of 29.5 months (range 0 to 193). Original prosthesis designs used were posterior-stabilized (53%), cruciate retaining (31%) and rotating hinge (16%). Dislocation was associated with a history of ligament laxity in 45.6% of patients, extensor mechanism deficiency in 35.5% and TKA infection in 25.9%. The mean follow-up post dislocation was 4.8 years (range 0.1 to 20.1). Non operative treatment was used for 29 knees and resulted in 25 knees experiencing further symptomatic instability. The remaining knees were treated by surgery. Of those treated by revision TKA (N=27) only 3 complained of symptomatic instability (P< 0.001).

Conclusions: TKA dislocation is a major complication. Conservative treatment is ineffective. Revision TKA reliably yields a stable knee in 89% of cases so treated. These results emphasize the importance of proper surgical technique, careful soft tissue balancing, and adequate constraint in the prevention and treatment of this problem.