Mid-term survivorship and clinical results of cementless total hip arthroplasty for steroid-induced avascular necrosis.

Objective: The purpose of the present study was to evaluate the mid-term implant survivorship, modes of failure, radiographic results, and clinical outcomes of current cementless total hip arthroplasty (THA) treatment designs for steroid-induced avascular necrosis (AVN).

Methods: A time span of 5 years between January 2012 and November 2017 was scanned to accommodate 5 years of follow-up and a total of 15 patients (18 hips), who had undergone implantation of ultra-high molecular weight polyethylene (UHMWPE) and newly designed other head and liner components, were included in the study. Only patients operated for steroid-induced AVN were included in the study. Patients with alcohol-induced, idiopathic, and traumatic AVN were excluded from the study. The primary outcomes were the assessments of Harris Hip Score (HHS) and the presence of loosening, osteolysis, polyethylene wear or a reoperation (with or without revision of components). The fixation of cementless femoral components was assessed according to Engh criteria.

Results: The study group consisted of 18 hips from 15 patients. The mean age was 47.6±8.1 (29-55) years. A cementless femoral stem and acetabular cup were used for all patients. Septic loosening was detected in all components of one patient (5.6%). The mean HHS score was 83.3±7.2 (60-92) for all patients. Of the 18 hips, 83% (15 hips), 5.6% (1 hip), 5.6% (1 hip), and 5.6% (1 hip) had good, poor, fair, and excellent HHS scores. Ceramic or polyethylene liner wear was not detected in any of the patients. The Engh Grading Scale revealed a "bone ingrowth" in 16 (89%) hips, "suspected in-growth" in 1 (5.6%) hip and "suboptimum but stable" femoral fixation in a patient with septic loosening (5.6%) just before revision surgery. There was no significant correlation between femoral stem design and Engh score (p=0.842).

Conclusion: Modern total hip arthroplasty systems, including ceramic on ceramic or ceramic on polyethylene headliner options with cementless femoral stem, offer promising mid-term survivorship and positive clinical outcomes for steroid-induced AVN treatment. However, studies including long-term follow-ups with larger sample size are needed to obtain more precise data.