In the past orthopaedic surgeons have kept their hands off from spontaneous or artificial fused hips, because those hips were painless, and the result of any further surgical procedure would be doubtful. In our days the need for conversion hip arthroplasty became a demand of patients having a better quality of life. In this paper we report on our results and the perioperative complications following conversion surgery.

Between 1993 and 2002 thirty-one hips of twentyfive patients (18 males, 7 females) were converted from totally stiff hip to total hip arthroplasty in the two most frequented orthopaedic hospitals in Budapest, Hungary (Semmelweis University, Medical School, Dept. of Orthopaedics & Hospital of Hospitaller Brothers of St.John of God, Dept. of Orthopaedics). The mean age of the patients was 47.2 years (ranging from 14 to 75 years) at the time of surgery. The average follow up was 50.7 months (2–176). At our 25 patients the hips became stiff 15.7 years ago as an average (3–61). Spontaneous fusion occured in 14 cases due to Bechterews disease (spondylitis ankylopoetica). In 4 cases fused hips were converted following arthrodesis procedures. There was no significant difference between each groups, spontaneous ankylosis and surgical fusion were similar, they were evaluated as stiff hips on the same way.

The indication for surgery was in most cases a painful lumbar spine or osteoarthritic knee joint on the ipsilateral side. The surrounding joints are obviously overloaded and overused because of the stiff hip joint, even though if the hip is painless.

27 cemented and 4 uncemented hip prostheses were implanted. The mean duration of conversion arthroplasties was 110 minutes, the perioperative blood loss was 1019 ml. Additional surgical procedures may be used, like intertrochanteric wedge resection, osteotomy of greater trochanter, muscle release from the iliac bone, tenotomy of the hip adductors or knee flexors.

The Harris Hip Score increased significantly from 34.2 to 81.3 (p< 0.01). The leg length discrepancy decreased from 4.0 cm to 1.2 cm, the difference of thigh circumference changed from 4.3 cm to 2.7 cm, all results as an average. Trendelenburgs gait was detected at 25 hips pre-op, and at 5 hips at the time of follow up. Five cases were reoperated due to haematoma formation, there was one prosthesis disclocation and one early septic complication.

Based upon the good clinical results at the follow up, we recommend to change the orthopaedic surgeons’ mind considering conversion arthroplasties. The surgical procedure can be performed securely, but it is technically challenging for each surgeon. The intraoperative use of fluoroscopy and preoperative planning are mandatory in conversion arthroplasty. Conversion arthroplasty is performed prior to severe degenerative changes in the surrounding joints.