Incidence and risk factors for unplanned readmission after total hip arthroplasty for osteonecrosis of the femoral head.

Objective: To investigate the incidence, primary causes, and risk factors for unplanned readmissions within one year after the first primary total hip arthroplasty (THA) for osteonecrosis of the femoral head (ONFH). Methods: Data were retrospectively collected from patients who had undergone the first primary THA for ONFH at two tertiary hospitals between January 2021 and December 2022, with complete 1-year follow-up assessments. Patients who experienced an unplanned readmission within 1 year were classified as the readmission group, while the others as the non-readmission group. The incidence rate and primary causes of unplanned readmission were determined, and the risk factors were identified through univariate and multivariate analyses. Results: A total of 594 eligible patients were included, with 363 being men (61.1%) and an average age of 59.2 years at the time of surgery. Forty-seven patients were readmitted within one year, representing an accumulated rate of 7.9%. Among these, 18 (38.3%) readmissions occurred within 30 days and 27 (57.4%) within 90 days. The primary reasons for readmissions included hip dislocation (35.3%), followed by periprosthetic fracture, deep vein thrombosis, delayed incision healing, surgical site infection and others. The multivariate regression model revealed that age (every 10-year increment, OR, 1.39; 95% CI, 1.12-1.88), ARCO stage IV vs. Ⅲ (OR, 3.72; 95% CI, 1.96-7.22), CCI ≥4 vs. <4 (OR = 5.49; 95% CI, 2.16-13.77), admission anemia (OR, 2.72; 95% CI, 1.37-6.83) and surgeon inexperience (OR, 2.74; 95% CI, 1.29-6.73) were significantly associated with unplanned readmission. Conclusions: These findings provide valuable clinical insights into unplanned readmission after THA for ONFH and may aid in preoperative counselling for patients and enhance perioperative care.