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

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 sympt...

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Bibliographic Details
Published in:Clinical orthopaedics and related research 2015-04, Vol.473 (4), p.1289-1296
Main Authors: Ng, K. C. Geoffrey, Lamontagne, Mario, Adamczyk, Andrew P., Rahkra, Kawan S., Beaulé, Paul E.
Format: Article
Language:English
Subjects:
Asymptomatic Diseases
Conservative Orthopedics
Femoracetabular Impingement - pathology
Femoracetabular Impingement - physiopathology
Femur Head - anatomy & histology
Femur Head - diagnostic imaging
Femur Neck - anatomy & histology
Femur Neck - diagnostic imaging
Hip
Hip Joint - diagnostic imaging
Hip Joint - pathology
Hip Joint - physiopathology
Humans
Male
Medicine
Medicine & Public Health
Orthopedics
Range of Motion, Articular
Sports Medicine
Surgery
Surgical Orthopedics
Symposium: 2014 Bernese Hip Symposium
Tomography, X-Ray Computed
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Summary: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 
ISSN:0009-921X
1528-1132
DOI:10.1007/s11999-014-3797-1