Hip Osteoarthritis MRI Scoring System (HOAMS): reliability and associations with radiographic and clinical findings

SummaryObjectiveTo develop a semiquantitative MRI-based scoring system (HOAMS) of hip osteoarthritis (OA) and test its reliability and validity.DesignFifty-two patients with chronic hip pain were included. 1.5T magnetic resonance imaging (MRI) was performed on all patients. Pelvic radiographs were scored according to the Kellgren–Lawrence (KL) system. Clinical outcomes were assessed by the hip osteoarthritis outcome score (HOOS). MRIs were analyzed using a novel whole-joint MRI score that incorporated 13 articular features. Reliability was determined on a random subset of 15 cases. Weighted-kappa statistics and overall agreement were used as a measure of intra- and inter-observer reliability. Associations between MRI features and radiographic OA severity were calculated using Cochran–Armitage test for trend. Ordinal logistic regression was used to assess associations between MRI features and severity of pain and functional limitation.ResultsDistribution of radiographic grading was: KL 0 = 12 (27%), KL 1 = 11 (25%), KL 2 = 14 (32%), KL 3 = 5 (11%) and KL 4 = 2 (5%). Intra-reader reliability for the different features ranged from 0.18 (cysts) to 0.85 (cartilage). Inter-reader reliability ranged between 0.15 (cysts) and 0.85 (BMLs). Low kappas were due to low frequencies of some features as overall percent agreement was good to excellent (83.8% and 83.1%). There was a strong association between MRI-detected lesions and radiographic severity (P = 0.002). Non-significant trends were observed between MRI features and clinical outcomes.ConclusionMRI-based semiquantitative assessment of the hip shows adequate reliability. Presence of more severe MRI-detected intraarticular pathology shows a strong association with radiographic OA. The results suggest possible associations between MRI-detected pathology and clinical symptoms.