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Patient-Specific Anatomical and Functional Parameters Provide New Insights into the Pathomechanism of Cam FAI

  • Symposium: 2014 Bernese Hip Symposium
  • Published:
Clinical Orthopaedics and Related Research®

An Erratum to this article was published on 25 September 2014

A Symposium: 2014 Bernese Hip Symposium to this article was published on 19 August 2014

Abstract

Background

Femoroacetabular impingement (FAI) represents a constellation of anatomical and clinical features, but definitive diagnosis is often difficult. The high prevalence of cam deformity of the femoral head in the asymptomatic population as well as clinical factors leading to the onset of symptoms raises questions as to what other factors increase the risk of cartilage damage and hip pain.

Questions/purposes

The purpose was to identify any differences in anatomical parameters and squat kinematics among symptomatic, asymptomatic, and control individuals and if these parameters can determine individuals at risk of developing symptoms of cam FAI.

Methods

Forty-three participants (n = 43) were recruited and divided into three groups: symptomatic (12), asymptomatic (17), and control (14). Symptomatic participants presented a cam deformity (identified by an elevated alpha angle on CT images), pain symptoms, clinical signs, and were scheduled for surgery. The other recruited volunteers were blinded and unaware whether they had a cam deformity. After the CT data were assessed for an elevated alpha angle, participants with a cam deformity but who did not demonstrate any clinical signs or symptoms were considered asymptomatic, whereas participants without a cam deformity and without clinical signs or symptoms were considered healthy control subjects. For each participant, anatomical CT parameters (axial alpha angle, radial alpha angle, femoral head-neck offset, femoral neck-shaft angle, medial proximal femoral angle, femoral torsion, acetabular version) were evaluated. Functional squat parameters (maximal squat depth, pelvic range of motion) were determined using a motion capture system. A stepwise discriminant function analysis was used to determine which of the parameters were most suitable to classify each participant with their respective subgroup.

Results

The symptomatic group showed elevated alpha angles and lower femoral neck-shaft angles, whereas the asymptomatic group showed elevated alpha angles in comparison with the control group. The best discriminating parameters to determine symptoms were radial alpha angle, femoral neck-shaft angle, and pelvic range of motion (p < 0.001).

Conclusions

In the presence of a cam deformity, indications of a decreased femoral neck-shaft angle and reduced pelvic range of motion can identify those at risk of symptomatic FAI.

Level of Evidence

Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

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Acknowledgments

We thank Kevin Dwyer and Giulia Mantovani, from the University of Ottawa’s Human Movement Biomechanics Laboratory, for their help with data collection and processing. We also thank Jae-Jin Ryu and Gillian Parker, from The Ottawa Hospital’s Division of Orthopedic Surgery, for their help with patient recruitment and data collection.

Author information

Authors and Affiliations

  1. Department of Mechanical Engineering, University of Ottawa, Ottawa, ON, Canada

    K. C. Geoffrey Ng MASc & Mario Lamontagne PhD

  2. School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada

    Mario Lamontagne PhD

  3. Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada

    Andrew P. Adamczyk MSc

  4. Department of Diagnostic Radiology, University of Ottawa, Ottawa, ON, Canada

    Kawan S. Rahkra MD

  5. Division of Orthopaedic Surgery, University of Ottawa, Ottawa, ON, Canada

    Paul E. Beaulé MD

Authors
  1. K. C. Geoffrey Ng MASc
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  4. Kawan S. Rahkra MD
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  5. Paul E. Beaulé MD
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Corresponding author

Correspondence to Paul E. Beaulé MD.

Additional information

One or more of the authors (ML, KSR, PEB) have received funding from the Canadian Institutes of Health Research.

All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research ® editors and board members are on file with the publication and can be viewed on request.

Clinical Orthopaedics and Related Research ® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA-approval status, of any drug or device prior to clinical use.

Each author certifies that his or her institution has approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained.

This work was performed at the Human Movement Biomechanics Laboratory, University of Ottawa, and at The Ottawa Hospital, Ottawa, Ontario, Canada.

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Ng, K.C.G., Lamontagne, M., Adamczyk, A.P. et al. Patient-Specific Anatomical and Functional Parameters Provide New Insights into the Pathomechanism of Cam FAI. Clin Orthop Relat Res 473, 1289–1296 (2015). https://doi.org/10.1007/s11999-014-3797-1

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  • DOI: https://doi.org/10.1007/s11999-014-3797-1

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