Diagnostic sensitivity and specificity of dynamic three-dimensional CT analysis in detection of cam and pincer type femoroacetabular impingement

Abstract

Background: Cam and pincer-type morphologies can cause femoroacetabular impingement syndrome (FAI) and can be measured on plain radiographs using the alpha angle and the center edge angle. As an addition to plain radiographs and to assess femoroacetabular impingement, it is possible to visualize the interplay of the acetabular and femoral morphology by means of dynamic three-dimensional simulation of hip joint. Therefore, the objective of this study is to compare alpha angles and center edge angles on plain radiographs with the dynamic computerized tomography (CT) analysis in patients with complaints of femoroacetabular impingement. Methods: All patients from our prospective cohort from 2012 to 2015 who underwent radiographs and a dynamic CT analysis for FAI were selected. Cam type morphologies were measured with the alpha angle and pincer type morphologies with lateral center-edge angle on radiographs and with CT analysis. The dynamic CT analysis also calculated position and size of impingement of femur and acetabulum. Intra-operative assessment was used to confirm impingement. Sensitivity, specificity and predictive values were calculated compared with respect to the intra-operative assessment. Results: A total of 127 patients were included. 90 cam morphologies and 45 pincer morphologies were identified intra-operatively. The sensitivity and specificity for cam morphology measured with radiographs was 84 and 72% compared to 90 and 43% with three dimensional dynamic analyses. The sensitivity and specificity for pincer morphology measured with radiographs was 82 and 39% compared to 84 and 51% with three dimensional dynamic analyses. Conclusions: Diagnostic accuracy is comparable in three-dimensional dynamic analysis of CT scans and radiographs representing FAI caused by cam or pincer type morphology.

Cam morphology but neither acetabular dysplasia nor pincer morphology is associated with osteophytosis throughout the hip: findings from a cross-sectional study in UK Biobank

“…Finally, our study is based on 2-dimensional imaging which limits our ability to detect differences in hip morphology in planes better visualised on 3-dimensional imaging 45 . Of note is that a recent study comparing x-rays with CT scans showed similar sensitivity and specificity between the two modalities when defining cam and pincer morphology 46 .…”

Combined 3-Dimensional CT and Multidirectional CT Arthrography for Femoroacetabular Impingement and Hip Lesions: A Cross-sectional Study Comparing Imaging and Hip Arthroscopic Surgery Findings

“…According to their results, patients who were diagnosed with cam-type FAI intraoperatively had 97% agreement with preoperative 3D-CT findings by radiologists. They found moderate agreement of 3D-CT findings with arthroscopic findings for cam-type lesions and concluded that the diagnostic assessment of patients with suspected FAI might be improved with the use of 3D-CT. Roling et al 31 reviewed 127 patients with FAI and compared the diagnostic strength of plain radiography and dynamic 3D-CT. According to their findings, the sensitivity and specificity of dynamic 3D-CT were 90% and 43%, respectively, for cam-type morphology and 84% and 51%, respectively, for pincer-type morphology.…”

Current and Future Advanced Imaging Modalities for the Diagnosis of Early Osteoarthritis of the Hip

“… 56 3D CT scans did not demonstrate superiority to plain radiographs in diagnosing CAM deformities but may have some use to surgeons for preoperative planning. 57 It is important to note that such techniques are not widely used, and these studies did not examine the use of 3D CT scans in detecting pre-OA.…”

“…Orthopedic Research and Reviews 2022:14 334 preoperative planning. 57 It is important to note that such techniques are not widely used, and these studies did not examine the use of 3D CT scans in detecting pre-OA.…”