PurposeTo evaluate the interrater reliability and accuracy of radiographs in assessing healing of osteochondral allografts (OCA) in the knee compared to computed tomography (CT) imaging. MethodsA retrospective review patients who underwent OCA transplantation of the knee was conducted. Postoperatively, knee radiographs were obtained at three and six months, and CT scans were obtained at six months. Three board-eligible orthopaedic surgeons independently graded postoperative radiographs, utilizing the grading scale established by Oladeji et al 2017, and the CT scans utilizing the grading scale established by Gelber et al 2021. Their consensus measurements served as a comparative gold standard. ResultsAmong 44 prospectively imaged grafts, 13 (29.5%) had radiographs at three months and 28 (63.6%) had radiographs available for evaluation at six months. Assessment of radiographic integration demonstrated low reliability (ICC: -0.02 to 0.14). On CT scan, this improved to fair reliability (k=0.29, p<0.001). However, Spearman rho between CT and XR grading demonstrated poor correlation (ρ = -0.23, p=0.04). Among six-month postoperative radiographs, accuracy of cyst identification was negatively correlated to greater degree of cystic changes from 90.9% (30/33 correct; no cystic changes) to 19.4% (7/36 correct; small cystic changes) and 33.3% (5/15 correct; large cystic changes). Overall true positive cyst detection rates on radiographs were 27.8% to 46.7%. ConclusionRadiographs demonstrate poor interrater reliability and accuracy in evaluation of healing after OCA transplantation of the knee. Notably, there was a high rate of missed cystic changes on radiographic analysis, as well as poor correlation of integration assessment with CT scan findings.
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