Total hip arthroplasty (THA) is a frequently performed, highly successful orthopedic procedure. Although primary osteoarthritis (PA) is the most common reason for (THA), there are several secondary conditions that lead to degenerative hip disease that are successfully treated with THA. The purpose of this study was to examine the incidence of these secondary causes of arthritis (SA) leading to THA and to compare the relative surgical costs, operating times, and hospital length of stay (LOS) for THA done for PA versus SA.
Electronic medical records from 836 continuous patients undergoing primary THA over a 2-year period were reviewed at a single high-volume joint arthroplasty center. Data obtained included age, sex, laterality, diagnosis leading to THA, surgical costs based on hospital fees, operating room time, and hospital LOS. Using operative reports, office visit notes, and radiology reports or images, patients were categorized into PA or SA groupings. PA was defined as osteoarthritis of no other known etiology, whereas SA was defined when a known underlying diagnosis led to degenerative joint disease of the hip. SA included hip dysplasia, post-traumatic arthritis (PTA), avascular necrosis (AVN), inflammatory arthropathy, Perthes disease, and slipped capital femoral epiphysis (SCFE). Means and proportions of the variables from both groups were analyzed and compared using t-tests and chi-squared tests where applicable.
There were 599 patients in the PA group and 237 patients in the SA group. The SA group was significantly younger than the PA group (54.4 years versus 64.0 years; p = 0.0001). The SA cohort had significantly higher mean surgical costs ($29,662 versus $27,078; p = 0.0005), operating room times (189 minutes versus 179 minutes; p = 0.0042), and LOS (4.2 days versus 3.9 days; p = 0.0312). Within the SA group, the hip dysplasia subgrouping had the lowest cost and operating room time, whereas the PTA subgrouping had the highest cost and operating room time.
More than a quarter of primary THAs are performed due to secondary arthritis, most commonly due to hip dysplasia. Cases of THA due to secondary arthritis are associated with significantly increased hospital costs, operating time, and postoperative length of stay compared to THA's performed for primary osteoarthritis. Patients with post-traumatic hip arthritis may contribute the highest economic burden and present the most complex cases for arthroplasty surgeons.