A Case of Recurrent Dislocation of the Posterior-Stabilized Total Knee Prosthesis

ABSTRACT

Dislocation of fixed bearing posterior stabilized total knee arthroplasty is very rare. There are several causes of postoperative dislocation such as malposition of the prosthesis, preoperative valgus deformity, a defect of the extensor mechanism and overwidening of the flexion gap. All of the three posterior dislocations of total knee arthroplasty occurred for the same design, which was the fixed bearing posterior stabilized type (TC-PLUS(R), Plus Orthopedics, Rotkreuz, Switzerland). The dislocations happened during full flexion with muscle relaxation and they could be manually reduced with the patient being given muscle relaxant. Each case showed two episodes of dislocation and there was no more dislocation in each case after quadriceps strengthening and walking exercise. In conclusion, this model requires modification of the design, including remodeling of the polyethylene spacer by heightening of the post.