AIMS: The effectiveness of total hip arthroplasty (THA) for patients with no or minimal radiological signs of osteoarthritis (OA) is unclear. In this study, we aimed to: 1) assess the outcome of such patients
2) identify patient comorbidities and CT or MRI findings which predicted outcome
and 3) compare their outcome to the expected outcome of THA for hip OA. METHODS: Adult patients undergoing THA for hip pain, with no or minimal radiological features of OA (Tönnis grading scale ≤ 1), were identified from a consecutive series of 1,925 THAs. Exclusion criteria were: inflammatory arthritis
osteonecrosis of the femoral head
prior trauma or infection
and patients without minimum one-year follow-up and patient-reported outcome measures (PROMs). The primary outcome measure was the Oxford Hip Score (OHS). Secondary outcome measures were EuroQol-visual analogue scale (EQ-VAS), University of California and Los Angeles (UCLA) scale, and patient satisfaction on a validated three-point 'better', 'same', or 'worse' scale. RESULTS: A total of 107 patients with a median age of 41 years (IQR 18 to 73) were included, with mean follow-up of 6.0 years (SD 3.1). All patients underwent a diagnostic hip injection as a decision aid. Median postoperative OHS was 34 (IQR 28 to 42), with 36 patients (33%) achieving a patient-acceptable symptom state (OHS ≥ 42), lower than THA patients in international registries (40 to 43 points). Secondary outcomes were UCLA of 6 (4 to 8) and EQ-VAS of 73 (51 to 80)
91/102 patients (89%) felt 'better' and would 'undergo surgery again'. Patients with chronic pain syndrome or hypermobility had lower OHS than patients without comorbidities (-6 points, p <
0.006). Overall, 84 patients had a CT and 34 patients an MRI. Patients with subchondral cysts (OHS 42 (37 to 45) vs 35 (26 to 36)
p = 0.014) or joint space narrowing on CT (OHS 42 (IQR 37 to 44) vs 35 (26 to 36)
p = 0.022) had higher function. CONCLUSION: Despite high satisfaction levels, patients undergoing THA with minimal or no radiological OA had lower postoperative function than typical THA patients. We recommend obtaining low-dose CT imaging and a diagnostic hip injection to aid decision-making.