Hemoglobinopathy is Associated With Total Hip Arthroplasty Indication Even Beyond Sickle Cell Anemia

Background: The extent to which hemoglobinopathies other than sickle anemia (HbSS) are associated with hip osteonecrosis is unknown. Sickle cell trait (HbS), hemoglobin SC (HbSC), and sickle/β-thalassemia (HbSβTh) may also predispose to osteonecrosis of the femoral head (ONFH). We sought to compare the distributions of indications for a total hip arthroplasty (THA) in patients with and without specific hemoglobinopathies. Methods: PearlDiver, an administrative claims database, was used to identify 384,401 patients aged 18 years or older undergoing a THA not for fracture from 2010 to 2020, with patients grouped by diagnosis code (HbSS N = 210, HbSC N = 196, HbSβTh N = 129, HbS N = 356). β-Thalassemia minor (N = 142) acted as a negative control, and patients without hemoglobinopathy as a comparison group (N = 383,368). The proportion of patients with ONFH was compared to patients without it by hemoglobinopathy groups using chi-squared tests before and after matching on age, sex, Elixhauser Comorbidity Index, and tobacco use. Results: The proportion of patients with ONFH as the indication for THA was higher among those with HbSS (59%, P <.001), HbSC (80%, P <.001), HbSβTh (77%, P <.001), and HbS (19%, P <.001) but not with β-thalassemia minor (9%, P =.6) than the proportion of patients without hemoglobinopathy (8%). After matching, the proportion of patients with ONFH remained higher among those with HbSS (59% vs 21%, P <.001), HbSC (80% vs 34%, P <.001), HbSβTh (77% vs 26%, P <.001), and HbS (19% vs 12%, P <.001). Conclusions: Hemoglobinopathies beyond sickle cell anemia were strongly associated with having osteonecrosis as the indication for THA. Further research is needed to confirm whether this modifies THA outcomes.