Clinical outcomes of total hip arthroplasty in patients with ankylosed hip.

Background: Hip ankylosis includes the limitation of hip motion and hip arthroplasty is the recommended treatment. This study aimed to evaluate the clinical and radiographic outcomes in the treatment of ankylosis of the hip joint by the Harris Hip Score (HHS). Methods: This interventional study was performed on patients with ankylosis in one or both hip joints, who were referred to Sina Hospital, Tehran, Iran from 2011-13. Electromyogram and nerve conduction studies were taken from the hip abductor muscles before surgery and HHS was calculated. Type of surgery and prosthesis, osteotomy required for the neck and trochanteric region of the femur, periprosthetic fracture and the need to restore the acetabulum were studied in the patients. Postoperative complications such as infection and dislocation at 3, 6 and 12 months after surgery were examined and then the HHS was calculated. Results: Seventy-seven patients (42 m/35 f) with a mean age of 36.71±11.78 years underwent total hip arthroplasty. Most causes of hip joint ankylosis in the patients were elderly osteoarthritis (20 cases) and avascular necrosis (13 cases). Electromyogram and nerve conduction studies showed high and low velocity conduction in 12 and 65 patients, respectively. We used the posterior approach in 55 patients (71.4%) and lateral approach in 22 patients (28.6%). Periprosthetic fracture occurred in two patients and 12 patients needed acetabular reconstruction. Standard prosthesis was used in 83.1% of patients. Six patients were excluded after six month and two patients were excluded after 12 month due to surgery complications. The mean HHS of patients before surgery was 48.53±6.28 and it progressed to 88.22±3.78 after 12 month (P<0.001). Conclusions: Total hip arthroplasty for patients with ankylosed hip can improve the range of joint motion, especially in the long-term follow-up. However, good results should be considered in the absence of pre- and post-operative complications.