Effect of bone type on clinical and radiographic outcomes of a proximally‐coated cementless stem in primary total hip arthroplasties

We determined the effect of pre‐operative bone structure upon the temporal effects of remodeling after total hip arthroplasty (THA) in a series of uncemented implants. We evaluated 345 patients (375 hips), who had either Dorr Type‐A (238 hips) or Type‐B (137 hips) bone, and who received a proximally‐coated cementless THA and were followed for a mean of 6 years. Outcomes evaluated included aseptic survivorship, Harris hip scores, and radiographic evaluation for patterns of remodeling. The aseptic survivorship (97.5% vs. 98%) and the mean final Harris hip scores (92 vs. 94 points) were similar between Types‐A and ‐B bone, respectively. Bone remodeling was seen significantly earlier and over a longer duration for patients who had Type‐B bone. At 5‐years, periprosthetic condensation (78% vs. 54%) and cortical hypertrophy (53% vs. 37%) were significantly higher and radiolucencies at any zone were lower (53% vs. 37%) in Type‐B compared to Type‐A bone. There was increased condensation in men and higher cortical hypertrophy in women. Various radiographic remodeling differences may not negatively impact clinical outcome at mid‐term follow‐up. Morphologic bone type appears to be predictive of physiologic response to loading.