Radiological pattern of hip osteoarthritis is associated with one-year patient-reported outcomes but not long-term mortality or revision after total hip arthroplasty : a retrospective case series.

Aims: This study aimed to determine the effect of the radiological patterns of hip osteoarthritis (OA) on patient-reported outcome measures (PROMs) at one year following total hip arthroplasty (THA) and their impact on long-term mortality and survivorship. Methods: This retrospective study assessed the outcomes of 445 patients with primary hip OA undergoing THA. Plain radiographs were assessed to determine the Kellgren-Lawrence grading, the radiological pattern of arthritis (hypertrophic, atrophic, or mixed) and the predominant location of wear. PROMs assessed included the EQ-5D-3L and Oxford Hip Score (OHS) preoperatively and at 12 months postoperatively. The minimum follow-up for surviving patients was 14.7 years. Across the cohort, including patients who died during follow-up, the mean follow-up was 12.3 years (1.0 to 15.6), with patients censored at death. Multivariable linear regression models were used to evaluate independent predictors of postoperative PROM scores, mortality, and revision. Results: In all, 284 females (63.5%) and 161 males (36.5%) were included. Females were more likely to have atrophic OA (n = 120; (42.3%) vs n = 47; (29.2%); p < 0.001). Males were more likely to have hypertrophic OA (n = 52; (32.3%) vs n = 47; (16.5%); p < 0.001). One-year PROM improvement differed by OA pattern: hypertrophic OA had the greatest mean improvement in OHS (+22.6 (SD 7.4)) and EQ-5D-3L (+0.45 (SD 0.32)), compared with mixed (+18.6 (SD 9.5), +0.35 (SD 0.32)) and atrophic OA (+17.3 (SD 11.3), +0.33 (SD 0.32)) OHS (p < 0.001) and EQ-5D-3L (p = 0.005). After adjustment for covariates, atrophic OA remained independently associated with lower postoperative OHS and EQ-5D-3L scores compared with hypertrophic OA. Mortality and revision rates did not differ between OA pattern groups. Conclusion: Radiological pattern of hip OA was associated with differences in one-year PROMs following THA. Patients with atrophic OA had smaller improvements following surgery compared with counterparts with hypertrophic OA. No differences were observed in long-term mortality or revision. Radiological pattern may represent a clinically relevant marker of postoperative functional improvement.