The Short Stem THA Provides Promising Results in Patients with Osteonecrosis of the Femoral Head.

BACKGROUND The short stem prosthesis showed good results in patients with primary osteoarthritis. However there were afew studies about the short stem total hip arthroplasty (THA) in patients with osteonecrosis of thefemoral head (ONFH). OBJECTIVE To evaluate the clinical and radiographic results of the short stem THA in patients with ONFH. The authors hypothesized that the short stem THA would be a promising procedure for patients with ONFH. MATERIAL AND METHOD The authors reviewed 120 osteonecrotic hips in 93 patients who underwent THA with Metha® short stem between November 2010 and February 2013. The appearance of bone trabeculae development and radiolucent line was reviewed using Gruen's classification. The Harris hip score (HHS) was recorded at 6, 12, 24, and 36 monthspostoperative for evaluating the clinical results. RESULTS The mean age of patients was 44.4 years (18-68) with the mean BMI of 22.7 (15.1-32.5, SD 3.5). The average follow-up period was 29.2 months (20-47). The mean HHS was significantly improved from 43.9 (22.7-74, SD 7.7) preoperatively to 97.7 (85.9-100, SD 2.7) at 6-month postoperatively (p < 0.01). The radiographic change around the stems showed bone trabeculae development at zone 1 (77 cases, 64.2%), 2 (27 cases, 22.5%), 3 (106 cases, 88.3%), 6 (120 cases, 100%), and 7 (115 cases, 95.8%). There was one case (0.8%) of 5 mm subsidence and the radiolucent line was observed in zone 1. There were six cases (5%) of intraoperativefemoralfractures and were treated with cerclage wires with nofurther subsidence observed There was one case (0.8%) of distal stem perforation that had stable bone ingrowth. No revision was required. CONCLUSION The clinical and radiographic results of the short stem THA in patients with ONFH are generally satisfactory. Its design enables preservation of the bone stock and the bone trabeculae appear to confirm the assumption of proximal force transmission. The authors believe that the short stem THA is a promising procedure for patients with ONFH.