Inter and intra-observer errors for postoperative total hip radiographic assessment using computer aided design.

Plain radiographic assessment of primary total hip arthroplasty following surgery remains to be the commonest radiological assessment. The current paper, studies the accuracy and concordance between observers reviewing these radiographs. A prospective radiographic and medical note review of ten patients who underwent total hip replacement for primary osteoarthritis, with a mean age of 69 years. Early and 6 weeks postoperative x-rays were assessed for hip profile and version profile using computer aided design (CAD) by two observers on two different occasions. The observers were Orthopaedic surgeons who perform arthroplasty of the hip. The results were analyzed statistically. Dimensions, including Femoral offset, medial offset and ilioischial offset showed a high degree of inter- film and intra-film correlation, with inter-class cor- relation (ICC) over 0.8. Except of the intra-film correlation of ilioischial offset measured on the post- operative films (p=0.067) by the first rater, all the intra and inter film correlation were significantly over the benchmark of 0.6. In terms of stem alignment, cup inclination and cup version, the intra-film correlation by rater n°2 ranges from 0.574 to 0.975 and were significantly over the benchmark of 0.6, except in the case of cup inclination measured on the 6 th​ week follow-up ; meanwhile the intra-film correlation by rater n°1 ranges from 0.581 to 0.819 and none were significantly over the benchmark of 0.6. The inter-rater reliability and inter-film correlation showed a dichotomy of results among different dimensions of the measurement. Dimensions of femoral offset, medial offset and ilioischial offset showed a substantial degree of reliability in terms of inter-rater reliability, inter-film correlation, and intra-rater/film reliability.