Ultrasound in osteoarthritis of the hand: a comparison to computed tomography and histology

Objective To compare structural findings between US, micro-CT (mu CT) and histology in people with OA of the hands. Methods We analysed DIP and PIP joints of 31 fingers from 15 dissecting-room cadavers with OA of the hands. The occurrence of bone erosions and osteophytes were recorded by US, mu CT and histology at 16 regions for each joint and compared for each method. Results In total, US (n = 558, 56.2% of 992 examined regions) and mu CT (n = 493, 49.7%) detected a higher frequency of osteophytes at PIP and DIP joints than histology (n = 161, 23.4% of 689 histological examined regions; P = 0.01). We found a comparable number of erosions with each method [US, n = 52 (5.2%); mu CT, n = 43 (4.3%); histology, n = 35 (5.2%)]. Both imaging techniques correlated moderately with each other regarding the detection of osteophytes (r = 0.54, P = 0.002) and erosions (r = 0.43, P = 0.017). Neither US nor mu CT correlated with histology regarding erosions or osteophytes. With histology as the reference, US had a sensitivity of 80% and a specificity of 32% to detect osteophytes, whereas mu CT had a sensitivity of 73% and a specificity of 27%. For erosions, sensitivities (US 10% and mu CT 6%, respectively) were much lower. Microscopically, erosions contained fibrous myxoid tissue extending from subcortical cavities through the breach of cortical bone. Conclusions The ability of US to identify osteophytes was comparable to that of mu CT, yielding a good sensitivity when histology was used as the gold standard. The sensitivity of US and mu CT to detecting erosions was low compared with histology.