Retained cement after unicondylar knee arthroplasty. A report of four cases.

The recent increase in the popularity of minimally invasive surgery has dramatically altered the technique that most surgeons use to perform unicondylar knee arthroplasty. This change in technique brings new difficulties to both the surgeon and the patient, such as the potential for new complications related to the limited surgical exposure and the need for surgeons to learn the new operative procedures. In this report, we describe the cases of four patients who required arthroscopic removal of a loose cement fragment after a minimally invasive unicondylar knee arthroplasty. We believe that this complication was related to the decreased visualization in the posterior compartment of the knee associated with the use of small incisions and cementing of the all-polyethylene tibial component. Our patients were informed that data concerning the cases would be submitted for publication. Case 1. A seventy-year-old man with a history of a left unicondylar knee replacement presented with increasing pain in the right knee. The findings on physical examination and radiographs were consistent with severe osteoarthritis of the medial compartment of the knee. In April 2003, the patient underwent a right unicondylar knee replacement through a minimally invasive incision. Both the femoral and the tibial components (Preservation; DePuy, Warsaw, Indiana) were cemented (Fig. 1). The thickness of the all-polyethylene tibial component was 9.5 mm. Fig. 1 Postoperative lateral radiograph showing the posterior cement mantle (arrowhead) fixed to the prosthesis. In June 2003, the patient presented with acute pain after feeling a “popping” in the right knee. Physical examination revealed a mild effusion and some ecchymosis about the posterior aspect of the knee. Radiographs revealed a fragment of cement that appeared to be lying free within the joint space (Fig. 2). Previous radiographs from the six-week postoperative examination showed that the cement fragment had been fixed to the posterior aspect …