Which factors are associated with a successful outcome following total hip arthroplasty in patients with early radiographic osteoarthritis?

Background: It is unclear which factors are associated with a successful total hip arthroplasty (THA) in patients with early radiographic osteoarthritis (OA).
Methods: 70 patients with early OA (Kellgren and Lawrence [KL] grades 0-2) who underwent THA were compared with 200 patients with advanced OA (KL grades 3-4). Outcomes were Oxford Hip Scores (OHS), EQ-5D and EQ-VAS scores; compared preoperatively with 1 year postoperatively. We investigated which clinical and radiographic (plain x-ray, CT, MRI) features predicted successful THA (postoperative OHS ⩾42).
Results: The early OA group were significantly younger (61 vs. 66 years; [ p   =  0.0035). There were no significant differences in BMI, ASA grade or gender. After adjusting for confounders, the advanced OA group had a significantly greater percentage of possible change (PoPC) in OHS (75.8% vs. 50.4%; p   <  0.0001) and improvement in EQ-5D (0.151 vs. 0.002; p   <  0.0001). There were no significant differences in complication, revision or readmission rates. In the early OA group, 16/70 (22.9%) patients had a 'successful' THA. Patients who had a 'successful' THA were significantly more likely to have subchondral cysts on CT/MRI (91.7% vs. 57.7%; p   =  0.0362). The presence of cysts on CT/MRI was associated with a significantly greater PoPC in OHS (61.6% vs. 38.2%; p   =  0.0353). The combination of cysts and joint space width <1 mm was associated with a PoPC of 68%.
Conclusions: THA in patients with early OA (KL grades 0-2) on plain radiographs should be indicated with caution. We advocate preoperative cross-sectional imaging in these patients. In the absence of cysts on CT/MRI, a THA seems unlikely to provide a satisfactory outcome.
Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: TNB: consultancy payments and patents from: DePuy Synthes; grants from: NIHR, Symbios; speaker payments from: DePuy Synthes, Corin, Symbios; travel/accommodation/meeting expenses from: DePuy Synthes, Corin, Symbios, and MatOrtho; unpaid shares in Eventum Orthopaedics, all unrelated to the study.All other author(s) declare that there is no conflict of interest.