PATTERN OF HIP OSTEOARTHRITIS ON PLAIN RADIOGRAPHS PREDICTS OUTCOME AT ONE YEAR FOLLOWING TOTAL HIP ARTHROPLASTY

Many classification systems exist for primary osteoarthritis (OA) of the hip. The primary aim of this study was to determine the effect of radiographic patterns of osteoarthritis on patient reported outcome measures (PROMs) in patients undergoing THR. This retrospective study assessed 445 patients with idiopathic osteoarthritis undergoing THR in a high-volume centre. Independent observers assessed radiographs to determine Kellgren-Lawrence OA grading and pattern of arthritis: hypertrophic, atrophic or mixed. Demographic and comorbidity data were collected. PROMs included pre-op and 1 year post operative EQ5D score and oxford hip score (OHS). 284 females (63.5%) and 161 males (36.5%) were included in the study. Females were more likely to have atrophic OA (120/284, 39% vs 47/161, 23%, p<0.05). Males were more likely to have hypertrophic OA (52/161, 37% vs 47/284, 23%). Overall OHS improvement at 1 year was significantly lower in the atrophic group (17.3 vs 22.6 (hypertrophic) and 18.6 (mixed), p<0.05). Patients with atrophic OA had smaller improvements in both pain and function components of the OHS at 1 year post op (p<0.05). EQ5D score improvement at 1 year was lower in patients with atrophic OA compared to hypertrophic OA (0.33 vs 0.45, p<0.05). Patient outcome following THR can be influenced by the radiographic pattern of their OA. Patients with atrophic OA report similar levels of pain and functional disability pre op but have a smaller improvement following surgery. Patients with hypertrophic OA have the largest improvements following surgery. Patients with atrophic OA should be made aware of potentially inferior outcomes.