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

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). 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. 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). 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.