The Degree of Pre-Operative Osteoarthritis is Associated with Outcome Following THA

Introduction: Total hip arthroplasty (THA) is increasingly used in less severe cases of hip osteoarthritis (OA).This paper aimed to determine 1) The prevalence of different degrees of OA before THA, 2) The association of pre-operative OA severity with the severity of baseline symptoms and 3) The association of pre-operative OA severity with outcomes post-THA. Methods: A retrospective study of a prospective database of all THAs at two tertiary academic centers between 2020 and 2021 was conducted. There were 803 patients in the database, with 109 being excluded due to incomplete data. There were 694 patients included, and the mean age and body mass index were 64.50±12.80 years and 28.45±5.90 kg/m2, respectively. Most patients were women (n=361; 52.0%). Radiographic analysis was performed to assess the degree of hip OA with the Tönnis grade (0 – 3; no OA – complete degradation). Patients had pre-operative patient-reported outcome measures (PROMs) of hip function via the Oxford Hip Score (OHS) and their overall well-being via the EQ-5D-5L, with follow-up and post-operative PROMs 12 months after surgery. Data analysis was performed using SPSS (IBM, Armonk, NY). Results: There were no differences in pre-operative OHS between Tönnis groups (18±6.26, n=14 in Tönnis 1, 21.19±8.27, n=260 in Tönnis 2 and 18.18±7.09, n=420 in Tönnis 3, p=0.14) After one year, the increase in OHS was 18.03±11.95, 18.32±10.96, and 24.32±9.98, respectively for Tönnis 1,2, and 3 (p<0.001). Thus, the percentage meeting the patient acceptable symptom state (PASS) was 57.1%, 60.8% and 72.6%. One year EQ-5D-5L was also highest in Tönnis 3 (47.5 ± 4.03, 79.6 ± 13.25 and 82.12 ± 11.67, p<0.001). Conclusion: The highest-grade OA before THA was correlated with the greatest improvements in hip function and quality of life. This study demonstrates that a conservative approach and re-education should be attempted in patients who have an absence of advanced radiographic OA.