Interobserver reliability of radiographic assessment after radial head arthroplasty

BACKGROUND: Radiographs are part of routine clinical care after radial head arthroplasty (RHA). Therefore, the aim of this diagnostic study was to assess the interobserver reliability of radiographic assessment following RHA. METHODS: Anteroposterior (AP) and lateral radiographs of 24 consecutive patients who underwent press-fit bipolar RHA were evaluated with respect to 14 parameters by 14 orthopaedic surgeons specializing in the elbow: shaft loosening (AP, lateral), subcollar bone resorption, nonbridging heterotopic ossification, capitellar erosion, capitellar osteopenia, implant size, ulnohumeral joint gapping, ulnohumeral joint degeneration, proximal radio-ulnar joint congruency, stem size, stem positioning (AP, lateral) and component dissociation or polyethylene wear of the head with increased angulation. Observer agreement was evaluated using the multirater kappa (κ) measure. RESULTS: Nine of 14 parameters had poor interobserver agreement [κ = 0.0 to 0.20, confidence interval (CI) = 0.0 to 0.31). Four parameters had fair agreement: subcollar bone resorption (κ = 0.27, CI = 0.12 to 0.40), capitellar erosion (κ = 0.30, CI = 0.20 to 0.40), ulnohumeral joint degeneration (κ = 0.35, CI = 0.22 to 0.51) and stem positioning in AP view (κ = 0.24, CI = 0.14 to 0.36). One parameter had moderate agreement: nonbridging heterotopic ossification (κ = 0.47, CI = 0.31 to 0.64). CONCLUSIONS: The overall interobserver reliability of radiographic assessment following press-fit bipolar RHA was poor among experienced elbow surgeons. Therefore, radiographic evaluation after RHA should be interpreted with caution when making treatment decisions.