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Dijkstra HP, Ardern CL, Serner A, Mosler AB, Weir A, Roberts NW, Mc Auliffe S, Oke JL, Khan KM, Clarke M, Glyn-Jones S. Primary cam morphology; bump, burden or bog-standard? A concept analysis. Br J Sports Med 2021; 55:1212-1221. [PMID: 34281962 PMCID: PMC8551977 DOI: 10.1136/bjsports-2020-103308] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2021] [Indexed: 12/27/2022]
Abstract
BACKGROUND Cam morphology, a distinct bony morphology of the hip, is prevalent in many athletes, and a risk factor for hip-related pain and osteoarthritis. Secondary cam morphology, due to existing or previous hip disease (eg, Legg-Calve-Perthes disease), is well-described. Cam morphology not clearly associated with a disease is a challenging concept for clinicians, scientists and patients. We propose this morphology, which likely develops during skeletal maturation as a physiological response to load, should be referred to as primary cam morphology. The aim of this study was to introduce and clarify the concept of primary cam morphology. DESIGN We conducted a concept analysis of primary cam morphology using articles that reported risk factors associated with primary cam morphology; we excluded articles on secondary cam morphology. The concept analysis method is a rigorous eight-step process designed to clarify complex 'concepts'; the end product is a precise definition that supports the theoretical basis of the chosen concept. RESULTS We propose five defining attributes of primary cam morphology-tissue type, size, site, shape and ownership-in a new conceptual and operational definition. Primary cam morphology is a cartilage or bony prominence (bump) of varying size at the femoral head-neck junction, which changes the shape of the femoral head from spherical to aspherical. It often occurs in asymptomatic male athletes in both hips. The cartilage or bone alpha angle (calculated from radiographs, CT or MRI) is the most common method to measure cam morphology. We found inconsistent reporting of primary cam morphology taxonomy, terminology, and how the morphology is operationalised. CONCLUSION We introduce and clarify primary cam morphology, and propose a new conceptual and operational definition. Several elements of the concept of primary cam morphology remain unclear and contested. Experts need to agree on the new taxonomy, terminology and definition that better reflect the primary cam morphology landscape-a bog-standard bump in most athletic hips, and a possible hip disease burden in a selected few.
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Affiliation(s)
- H Paul Dijkstra
- Department for Continuing Education, University of Oxford, Oxford, UK .,Department of Medical Education, Aspetar Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Clare L Ardern
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University College of Science Health and Engineering, Bundoora, Victoria, Australia.,Musculoskeletal and Sports Injury Epidemiology Center, Sophiahemmet University, Stockholm, Sweden
| | - Andreas Serner
- Research & Scientific Support, Aspetar Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Andrea Britt Mosler
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University College of Science Health and Engineering, Bundoora, Victoria, Australia
| | - Adam Weir
- Aspetar Sports Groin Pain Centre, Aspetar Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.,Department of Orthopaedics and Sports Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - Nia Wyn Roberts
- Bodleain Health Care Libraries, University of Oxford Bodleian Libraries, Oxford, UK
| | - Sean Mc Auliffe
- Department of Physical Therapy & Rehabilitation Science, Qatar University, Doha, Qatar
| | - Jason L Oke
- Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
| | - Karim M Khan
- Family Practice & Kinesiology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Mike Clarke
- Northern Ireland Methodology Hub, Queen's University Belfast, Belfast, UK
| | - Siôn Glyn-Jones
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
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Using a numerical method to precisely evaluate the alpha angle in a hip image. Med Biol Eng Comput 2019; 57:1525-1535. [PMID: 30963390 DOI: 10.1007/s11517-019-01973-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Accepted: 03/12/2019] [Indexed: 10/27/2022]
Abstract
The alpha angle is a parameter extensively used to assess for cam-type femoroacetabular impingement (FAI) in a 2D image of the hip. As this angle requires estimation of the axis of the femoral neck, the drawing of this axis often results in measurement errors due to subjective judgment, influencing inter-rater and intra-rater agreements. In the present study, sampling points were captured from the edges of a femoral neck and head in the 2D image, and the best curves of the two were fitted respectively by using the curve fitting method. The morphology of the femoral neck was outlined by two polynomials, and the femoral head was represented by an equation of a circle. By means of the proposed method, the results reveal that the inter-rater ICCs in X-ray and MRI were respectively 0.905 and 0.969, and the intra-rater ICCs in X-ray and MRI were respectively 0.892 and 0.840. The Bland-Altman plot shows that the values obtained by the proposed method and the conventional method were not consistent; nevertheless, the linear regression analysis indicated the two measurement results had a significant association (p < 0.001). This study provides a repeatable and agreed α angle measuring method, which contributes to identifying normal and abnormal femoral head-neck morphologies. The proposed numerical method would contribute to diagnose early FAI.
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Cooper RJ, Williams S, Mengoni M, Jones AC. Patient-specific parameterised cam geometry in finite element models of femoroacetabular impingement of the hip. Clin Biomech (Bristol, Avon) 2018; 54:62-70. [PMID: 29554551 DOI: 10.1016/j.clinbiomech.2018.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 03/02/2018] [Accepted: 03/13/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Impingement resulting in soft tissue damage has been observed in hips with abnormal morphologies. Geometric parameterisation can be used to automatically generate a range of bone geometries for use in computational models, including femurs with cam deformity on the femoral neck. METHODS This study verified patient-specific parametric finite element models of 20 patients with cam deformity (10 female, 10 male) through comparison to their patient-specific segmentation-based equivalents. The parameterisation system was then used to generate further models with parametrically defined geometry to investigate morphological changes in both the femur and acetabulum and their effects on impingement. FINDINGS Similar findings were observed between segmentation-based and parametric models when assessing soft tissue strains under impingement conditions, resulting from high flexion and internal rotations. Parametric models with cam morphology demonstrated that clinically used alpha angles should not be relied on for estimating impingement severity since planar views do not capture the full three-dimensional geometry of the joint. Furthermore, the parametric approach allowed study of labral shape changes, indicating higher strains can result from bony overcoverage. INTERPRETATION The position of cams, as well as their size, can affect the level of soft tissue strain occurring in the hip. This highlights the importance of reporting the full details of three-dimensional geometry used when developing computational models of the hip joint and suggests that it could be beneficial to stratify the patient population when considering treatment options, since certain morphologies may be at greater risk of elevated soft tissue strain.
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Affiliation(s)
- Robert J Cooper
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK.
| | - Sophie Williams
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
| | - Marlène Mengoni
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
| | - Alison C Jones
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
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Cooper RJ, Mengoni M, Groves D, Williams S, Bankes MJ, Robinson P, Jones AC. Three-dimensional assessment of impingement risk in geometrically parameterised hips compared with clinical measures. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:e2867. [PMID: 28112875 PMCID: PMC5724697 DOI: 10.1002/cnm.2867] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/17/2017] [Accepted: 01/18/2017] [Indexed: 06/06/2023]
Abstract
Abnormal bony morphology is a factor implicated in hip joint soft tissue damage and an increased lifetime risk of osteoarthritis. Standard 2-dimensional radiographic measurements for diagnosis of hip deformities, such as cam deformities on the femoral neck, do not capture the full joint geometry and are not indicative of symptomatic damage. In this study, a 3-dimensional geometric parameterisation system was developed to capture key variations in the femur and acetabulum of subjects with clinically diagnosed cam deformity. The parameterisation was performed for computed tomography scans of 20 patients (10 female and 10 male). Novel quantitative measures of cam deformity were taken and used to assess differences in morphological deformities between males and females. The parametric surfaces matched the more detailed, segmented hip bone geometry with low fitting error. The quantitative severity measures captured both the size and the position of cams and distinguished between cam and control femurs. The precision of the measures was sufficient to identify differences between subjects that could not be seen with the sole use of 2-dimensional imaging. In particular, cams were found to be more superiorly located in males than in females. As well as providing a means to distinguish between subjects more clearly, the new geometric hip parameterisation facilitates the flexible and rapid generation of a range of realistic hip geometries including cams. When combined with material property models, these stratified cam shapes can be used for further assessment of the effect of the geometric variation under impingement conditions.
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Affiliation(s)
- Robert J. Cooper
- Institute of Medical and Biological Engineering, School of Mechanical EngineeringUniversity of LeedsLeedsLS2 9JTUK
| | - Marlène Mengoni
- Institute of Medical and Biological Engineering, School of Mechanical EngineeringUniversity of LeedsLeedsLS2 9JTUK
| | - Dawn Groves
- Institute of Medical and Biological Engineering, School of Mechanical EngineeringUniversity of LeedsLeedsLS2 9JTUK
| | - Sophie Williams
- Institute of Medical and Biological Engineering, School of Mechanical EngineeringUniversity of LeedsLeedsLS2 9JTUK
| | | | - Philip Robinson
- Leeds Musculoskeletal Biomedical Research UnitChapel Allerton HospitalLeedsLS7 4SAUK
| | - Alison C. Jones
- Institute of Medical and Biological Engineering, School of Mechanical EngineeringUniversity of LeedsLeedsLS2 9JTUK
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