抄録
Habitual patellar dislocation is treated by surgical procedures such as proximal-realignment and distal realignment; however, it is difficult to cure this condition using either of these methods alone. Here we describe mobile-bearing total knee arthroplasty (TKA) for a case of severe knee osteoarthritis complicated by habitual patellar dislocation since childhood, for which good results were obtained without the need for any additional procedures.
The patient was an 82-year-old woman with severe pain in the left knee. During the initial examination, the range of motion of the left knee joint was －10° of extension to 140° of flexion, and the Japanese Orthopaedic Association (JOA) score for knee osteoarthritis was 40 points. Preoperative radiographs demonstrated a varus deformity in the left lower extremity with a femorotibial angle (FTA) of 188°, the axial view showed luxation of the patella.
We performed TKA using a mobile-bearing implant. Intraoperative findings revealed that the central articular surface of the distal femur had disappeared, and that the patellar articular surface was concave and dome-shaped. The lateral patellofemoral ligament was released; this procedure was identical to that performed in conventional TKA.
Postoperative radiographs showed good alignment, with a FTA of 172°. In the axial view, the patella was located in a reduced position at any angle of knee joint flexion.
The postoperative range of motion of the left knee joint was 0° of extension to 130° of flexion. The patient was able to walk without the support of a T-shaped cane.
There are many surgical treatments for habitual patellar dislocation. The appropriate treatment is selected according to the type and seriousness of the dislocation and the age of the patient.
From the findings of the present case, we believe that in a case of knee osteoarthritis complicated by habitual patellar dislocation, surgery performed using a mobile-bearing implant would eliminate the necessity of performing additional proximal realignment and distal realignment.
