The degree of pre-operative osteoarthritis is associated with outcome following THA

Total hip arthroplasty (THA) is increasingly offered for less severe 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.

A retrospective study of a database of all THAs at two tertiary academic centers between 2020 and 2021 was conducted. There were 803 patients and 109 were excluded due to incomplete data. Overall, 694 patients were 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%). Radiographs were assessed for degree of hip OA via the Tönnis grade (0-3; no OA - complete degradation). Patients had pre-operative patient-reported outcome measures (PROMs) of hip-pain (Oxford Hip Score (OHS)) and overall well-being (EQ-5D-5 L), both pre-operatively and 1 year after surgery. Data analysis was performed using SPSS (IBM, Armonk, NY).

There were 14 (2%) cases of Tönnis 1 OA, 260 (37.5%) Tönnis 2, and 420 (60.5%) Tönnis 3. Pre-operative OHS was similar between 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). Multivariate regression models showed that Tönnis 3 patients had the highest 1-year OHS scores, independent of other variables. 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). One year EQ-5D-5 L was also highest in Tönnis 3 (47.5 ± 4.03, 79.6 ± 13.25 and 82.12 ± 11.67, p < 0.001).

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.