Abstract
Background
The short stem prosthesis showed good results in patients with primary osteoarthritis. However, there were a few studies about the short stem THA in patients with osteonecrosis of the femoral 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 from November 2010 to 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 months postoperative 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 months 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 1 case (0.8%) of 5 mm subsidence and the radiolucent line was observed in zone 1. There were 6 cases (5%) of intraoperative femoral fractures and were treated with cerclage wires, no further subsidence was observed. There was 1 case (0.8%) of distal stem perforation which 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.
