Abstract
We report a case of coxitis knee in which revision total knee arthroplasty (TKA) was performed using a constraint-type implant because severe valgus instability had resulted from the primary TKA. A 77-year-old woman with congenital dislocation of the hip had left gonalgia and gait disorder. She had undergone initial TKA in another hospital at age 66. Severe valgus instability of the left knee and relative lower left limb shortening were observed. Both hip joints had an abduction limit of 10°. X-ray investigation showed that the wear on the TKA was severe, and the femorotibial angle was 130°. Both hip joints had advanced dislocations of Crowe type IV. We diagnosed her condition as coxitis knee presenting with high valgus instability caused by the abduction limit of the ipsilateral hip joint. The ipsilateral THA and the separation of the adductor muscles were reinforced. Revision TKA was reinforced four months later. Because the medial loosening was severe, a restrictive-type TKA (Biomet OSS) was used. The gonalgia disappeared after surgery, and improvement in gait was obtained. Both ipsilateral knee dysfunction originating from adduction contracture of the hip joint and contralateral knee dysfunction caused by length differences in the lower limbs have been reported; the latter condition is known as long leg arthropathy. This case was considered to be knee dysfunction caused by the abduction limit of the hip joint. Excessive valgus stress might have resulted from medial collateral ligament dysfunction and the severe wear of the insert. Two or more factors may contribute to coxitis knee, and examining the condition based on the overall balance of both lower limbs is necessary.
