Posterior dislocation of a cruciate-retaining total knee arthroplasty following an acute bacterial infection

Background: We report a rare complication of posterior dislocation of a cruciate-retaining total knee arthroplasty following an acute bacterial infection. The mechanism of dislocation proved to be septic loosening of the femoral component and a tear of the posterior cruciate ligament near to the femoral insertion site. The tear arose during the treatment of acute septic arthritis following total knee arthroplasty when the patient attempted full weight-bearing with the affected limb in a semiflexion position and twisted the knee. Methods and results: Successful treatment was provided with subsequent surgical debridement, removal of the loosened prosthesis, the application of systemic antibiotics, and a revision total knee arthroplasty utilizing a posteriorly stabilized prosthesis after adequate control of the infection. Conclusion: Soft-tissue protection from full weight-bearing of the knee during the treatment of an acute infection following total knee arthroplasty and timely removal of the loosened total knee prosthesis are recommended in order to prevent such a complication.