ObjectiveTo explore the effectiveness of total hip arthroplasty (THA) for non-functional bony ankylosed hip in young and middle-aged patients. MethodsBetween January 2010 and March 2013, 14 cases (19 hips) of non-functional bony ankylosed hip were treated by THA. There were 9 males and 5 females, aged 37.5 years on average (range, 23-58 years). The left hip was involved in 6 cases, the right hip in 3 cases, and bilateral hips in 5 cases. The causes were tuberculosis in 2 patients, ankylosing spondylitis in 5 patients, traumatic arthritis in 5 patients, osteoarthritis in 1 patient, and suppurative infection in 1 patient. The disease duration was 7-18 years with an average of 8.9 years. Flexion stiffness was observed in 10 hips, flexion abduction stiffness in 6 hips, and flexion adduction shortening stiffness in 3 hips. Only 5 patients could walk with a crutch before operation. Harris hip score was 24.368±7.625. ResultsThe average operation time was 63.4 minutes (range, 50-90 minutes). The average intraoperative blood loss was 196.8 mL (range, 100-400 mL). Patients obtained primary healing of incision; no complication of neurovascular injury, fracture, joint dislocation, or infection occurred. All patients were followed up 2.2 years on average (range, 1 year to 4 years and 3 months). The Harris score was 86.837±7.742 at last follow-up, showing significant difference when compared with preoperative score (t=-41.956, P=0.000). The results were excellent in 5 hips, good in 11 hips, fair in 2 hips, and poor in 1 hip, with an excellent and good rate of 84.2%. All patients could basically take care of themselves; 2 patients could walk with crutch, and the other patients could walk without crutch. X-ray films showed that prosthesis was in good position; no shifting, loosening, or sinking was found. Heterotopic ossification occurred in 2 hips. ConclusionTHA is an effective surgical approach to treat non-functional bony ankylosed hip in young and middle-aged patients.