Assessment of radiolucent lines in cemented shoulder hemi-arthroplasties: study of concordance and reproducibility.

We report on the concordance and reproducibility of the evaluation of radiolucent lines in the humeral component of shoulder arthroplasty. Thirty-two shoulder prostheses were assessed independently, on two occasions, by five observers. The level of inter- and intra-observer agreement was calculated using the kappa statistic. Intra-observer agreement: the overall kappa values ranged from 0 to 0.6, meaning poor, fair and moderate agreement levels. Inter-observer agreement: when the anteroposterior (AP) views were analysed, the values obtained for the bone-cement interface ranged from 0.290 to 0.539, meaning a poor-to-moderate agreement. For the cement-implant interface, the values ranged from 0.064 to 0.684, meaning a poor-to-good agreement. When radiolucent lines of the humeral component were analysed, inter-observer agreement proved to be as low as that obtained when total hip or knee components were analysed. Intra-observer agreement showed better results.