caa a22 4500 605456798 CHVBK 20210128100219.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s00167-014-3182-3 doi (NATIONALLICENCE)springer-10.1007/s00167-014-3182-3 Relationship between the alpha and beta angles in diagnosing CAM-type femoroacetabular impingement on frog-leg lateral radiographs [Elektronische Daten] [Moin Khan, Anil Ranawat, Dale Williams, Rajiv Gandhi, Hema Choudur, Naveen Parasu, Nicole Simunovic, Olufemi Ayeni] Purpose: Alpha and beta angles are commonly used radiographic measures to assess the sphericity of the proximal femur and distance between the pathologic head-neck junction and the acetabular rim, respectively. The aim of this study was to explore the relationship between these two measurements on frog-leg lateral hip radiographs. Methods: Fifty frog-leg lateral hip radiographs were evaluated by two orthopaedic surgeons and two radiologists. Each reviewer measured the alpha and beta angles on two separate occasions to determine the relationship between positive alpha and beta angles and the inter- and intra-observer reliability of these measurements. Results: There was no significant association between positive alpha and beta angles, [kappa range −0.043 (95% CI −0.17 to 0.086) to 0.54 (95% CI 0.33-0.75)]. Intra-observer reliability was high [alpha angle intra-class correlation coefficient (ICC) range 0.74 (95% CI 0.58-0.84) to 0.99 (95% CI 0.98-0.99) and beta angle ICC range 0.86 (95% CI 0.76-0.92) to 0.97 (95% CI 0.95-0.98)]. Conclusions: There is no statistical or functional relationship between readings of positive alpha and beta angles. The radiographic measurements resulted in high intra-observer and fair-to-moderate inter-observer reliability. Results of this study suggest that the presence of a CAM lesion on lateral radiographs as suggested by a positive alpha angle does not necessitate a decrease in clearance between the femoral head and acetabular rim as measured by the beta angle and thus may not be the best measure of functional impingement. Understanding the relationship between these two aspects of femoroacetabular impingement improves a surgeon's ability to anticipate potential operative management. Level of evidence: III. Springer-Verlag Berlin Heidelberg, 2014 Alpha angle nationallicence Beta angle nationallicence Relationship nationallicence FAI nationallicence Khan Moin Division of Orthopaedics, Department of Surgery, McMaster University, Hamilton, ON, Canada aut Ranawat Anil Hospital for Special Surgery, New York, NY, USA aut Williams Dale Division of Orthopaedics, Department of Surgery, McMaster University, Hamilton, ON, Canada aut Gandhi Rajiv Division of Orthopaedic Surgery, University of Toronto, Toronto, ON, Canada aut Choudur Hema Department of Radiology, McMaster University, Hamilton, ON, Canada aut Parasu Naveen Department of Radiology, McMaster University, Hamilton, ON, Canada aut Simunovic Nicole Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada aut Ayeni Olufemi Division of Orthopaedics, Department of Surgery, McMaster University, Hamilton, ON, Canada aut Knee Surgery, Sports Traumatology, Arthroscopy Springer Berlin Heidelberg 23/9(2015-09-01), 2595-2600 0942-2056 23:9<2595 2015 23 167 https://doi.org/10.1007/s00167-014-3182-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00167-014-3182-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Khan Moin Division of Orthopaedics, Department of Surgery, McMaster University, Hamilton, ON, Canada aut NATIONALLICENCE 700 1- Ranawat Anil Hospital for Special Surgery, New York, NY, USA aut NATIONALLICENCE 700 1- Williams Dale Division of Orthopaedics, Department of Surgery, McMaster University, Hamilton, ON, Canada aut NATIONALLICENCE 700 1- Gandhi Rajiv Division of Orthopaedic Surgery, University of Toronto, Toronto, ON, Canada aut NATIONALLICENCE 700 1- Choudur Hema Department of Radiology, McMaster University, Hamilton, ON, Canada aut NATIONALLICENCE 700 1- Parasu Naveen Department of Radiology, McMaster University, Hamilton, ON, Canada aut NATIONALLICENCE 700 1- Simunovic Nicole Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada aut NATIONALLICENCE 700 1- Ayeni Olufemi Division of Orthopaedics, Department of Surgery, McMaster University, Hamilton, ON, Canada aut NATIONALLICENCE 773 0- Knee Surgery, Sports Traumatology, Arthroscopy Springer Berlin Heidelberg 23/9(2015-09-01), 2595-2600 0942-2056 23:9<2595 2015 23 167