Case Report Recurrent Total Knee Arthroplasty Dislocation After Dorsal Meningioma Diagnosed Yaiza Lopiz, MD, PhD, Carlos García-Fernández, MD, Fernando Marco, MD, PhD, and Luis López-Durán, MD, PhD Abstract: We report on a 68-year-old woman with gonarthrosis who underwent total knee arthroplasty. Having initially achieved a satisfactory result, she developed at 5 months postoperation an irreducible flexion contracture necessitating revision surgery; but no pathological findings were discovered. In the immediate postoperative period, the patient developed a severe spasm of the hamstring muscles and a paralysis of the external popliteal sciatic nerve with a posterior dislocation of the knee. After reduction, an electromyography study showed an alteration in medullary sensitive conduction; and the magnetic resonance image showed a lesion compatible with meningioma. This complication has not been previously described as a consequence of spinal tumor. Technical considerations are described for this rare complication, which remains a serious challenge for the orthopedic surgeon. Keywords: meningioma, total knee arthroplasty, dislocation. © 2011 Elsevier Inc. All rights reserved. Case Report A 68-year-old woman was diagnosed with primary osteoarthritis of the right knee, and a cemented posterior stabilized total knee prosthesis with mobile-bearing (DePuy PFC Sigma,Warsaw, Ind) was implanted. No intraoperative complications occurred, and the patient was discharged home on the sixth postoperative day with a range movement of 90° of flexion and complete extension (Fig. 1A). On the fifth month after total knee arthroplasty, the patient presented a fixed flexion contracture (85°) and pain. She did not suffer any traumatic incident, and she did not present other signs or symptoms that sug- gested infection or aseptic loosening of the prosthesis. The laboratory data and the results of radiographic study were normal. In view of the presence of a nonreducible flexion contracture of the knee and the suspicion of a possible dislocation or breakage of the polyethylene insert, operative revision was undergone. The results of histological studies (presence of polymorphonuclear neutrophils) and cultures of specimens of periprosthetic tissue that had been obtained during the surgery were negative. At the time of macroscopic examination, no signs of dislocation or breakage of the polyethylene insert were found; and the prosthesis was implanted correctly without macroscopic signs of infection and with good stability on varus-valgus testing. In this situation, we decided to extract the femoral component and make an overresection of the distal femur with a progressive posterior capsular release to increase flexion gap. After this, the knee had good stability and presented complete extension. Hence, the knee was immobilized in 10° flexion with a cylinder cast. In the immediate postoperative period, the patient developed a severe spasm of her hamstring muscles, breaking the cast because of flexion contracture; and a new RX showed a posterior prosthesis dislocation (Fig. 1B). Reduction was done under image intensifier guidance on the same day. Because of the trend toward flexion contracture, the appearance of numbness in the lower extremities, and the development of a progressive external popliteal sciatic nerve paralysis, electromyog- raphy study was ordered. This study showed a severe alteration in medullary sensitive conduction and more affectation of the right side. Magnetic resonance imaging From the Department of Orthopaedic Surgery, Hospital Clínico San Carlos, Madrid, Spain. Submitted May 13, 2009; accepted November 11, 2010. The Conflict of Interest statement associated with this article can be found at doi:10.1016/j.arth.2010.11.018. Reprint requests: Yaiza Lópiz-Morales, MD, PhD, Calle Azafrán n°1, 3°D, CP:28222. Majadahonda, Madrid, Spain. © 2011 Elsevier Inc. All rights reserved. 0883-5403/2608-0073$36.00/0 doi:10.1016/j.arth.2010.11.018 1570.e9 The Journal of Arthroplasty Vol. 26 No. 8 2011