Femoroacetabular impingement and classification of the cam deformity: the reference interval in normal hips

Pollard, T. C. B.; Villar, Richard N.; Norton, M.R.; Fern,; Williams, Mark R.; Simpson, David J. W.; Murray, David; Carr, Andrew

doi:10.3109/17453671003619011

Cited by 150 publications

(150 citation statements)

References 26 publications

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“…However, not all hips with abnormal joint morphology develop symptoms. A cam deformity is a common finding (approximately 20% incidence) in asymptomatic male subjects [4][5][6][7] and patients with FAI often have similar deformities in the contralateral asymptomatic hip [8]. This supports the notion that additional variables, such as the vulnerability of the labrum and articular cartilage to injury, and activity level, are important in modulating whether abnormal morphology results in symptoms.…”

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confidence: 56%

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A perspective on femoroacetabular impingement

Pollard

2011

Skeletal Radiol

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Although Smith-Petersen described impingement of the native hip in 1936 [1], the success of replacement arthroplasty of the hip dominated the orthopaedic literature until the early contemporary reports of femoroacetabular impingement (FAI) at the turn of the millennium [2]. Subsequently, an exponential increase in interest in the subject has occurred, as demonstrated by the annual number of Pubmed hits for FAI, which reached 168 in 2010 alone. This interest is perhaps not surprising when one considers that FAI represents a new diagnosis for young adults with hip pain, an opportunity for advanced imaging and surgical techniques, and perhaps most tantalisingly, the possibility of altering the natural history of degenerative joint disease and limiting progression to endstage osteoarthritis (OA). With the explosion of recent interest in FAI, there are many controversies and unresolved issues that will be the targets for research over the next decade. Aetiology of FAIFemoroacetabular impingement may occur secondary to paediatric hip disease or trauma, but the vast majority of cases have no underlying known cause and may be considered "primary FAI". A hip with symptomatic FAI is likely to differ from a "normal" hip through a combination of its morphology, durability of its articular cartilage and labrum, and demands placed upon it, with regard to the range of movement and activity level of the patient. Recent evidence suggests a strong genetic component to FAI [3], which is in keeping with the known genetic predisposition to hip OA. Whether abnormal morphology is determined at conception, or is acquired during skeletal development, is not known. It is conceivable that there is a genetic predisposition to subclinical slipped capital femoral epiphysis, for example. However, not all hips with abnormal joint morphology develop symptoms. A cam deformity is a common finding (approximately 20% incidence) in asymptomatic male subjects [4][5][6][7] and patients with FAI often have similar deformities in the contralateral asymptomatic hip [8]. This supports the notion that additional variables, such as the vulnerability of the labrum and articular cartilage to injury, and activity level, are important in modulating whether abnormal morphology results in symptoms. The importance of activity type and intensity needs further investigation. It stands to reason that an activity such as hurdling will potentially damage an at-risk hip by increasing the frequency and severity of impingement episodes. Better ways of grading activity are required in order to classify individuals. With regard to morphology, very little is known regarding the development of the nondysplastic hip through childhood and adolescence, and prospective studies during skeletal development may help to determine whether morphology is dependent on activity or other factors. Longitudinal studies of well-characterised cohorts will improve our understanding of how FAI develops. Difficulties with imagingIt is crucial to appreciate that making a diagnosis of FAI relies on...

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confidence: 56%

“…However, the reliability of its measurement has been questioned [10,11]. The 50°threshold may be extrapolated to lateral radiographs [12], but this assumption has not been validated and the abnormal threshold may be as high as 62°with this method [5]. A threshold of 55°has been suggested based on CT [13].…”

Section: Difficulties With Imagingmentioning

confidence: 99%

A perspective on femoroacetabular impingement

Pollard

2011

Skeletal Radiol

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“…Moreover, other common radiographic measures of the femoral head and neck and acetabulum have been associated with symptomatic FAI [5,10,26,40], but it remains unclear as to which combination of parameters plays a role in identifying patients at risk of developing symptoms. Although patients have demonstrated higher hip stresses [35] and different hip kinematics at higher ROMs such as during maximal squatting [31,32], it is still unclear why many individuals with cam deformity do not exhibit any clinical signs [22,38,40].…”

Section: Introductionmentioning

confidence: 99%

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

Lamontagne

Adamczyk

et al. 2015

Clinical Orthopaedics &Amp; Related Research

104

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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

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“…This greater strain is the main cause of ACL rupture in these patients (11,(13)(14)(15). Decrease in hip range of motion is multifactorial, one of the most important factors in femoroacetabular impingement which can cause restriction in hip range of motion, especially internal rotation, so can cause increase in ACL strain during landing and pivoting (8,9). Philippon showed a significant decrease in hip offset in ACL injured patients (9).…”

Section: Discussionmentioning

confidence: 99%

“…Recent studies mentioned the complex structural anatomic variants of the hip joint like femoral or acetabular retroversion, femoral notch geometry, extraarticular impingement and femoroacetabular impingement that are associated with restriction in internal rotation of the hip, which can result in increased risk of ACL injury (4,6,8,9). Femoroacetabular impingement (FAI) is one of the main causes of restriction in hip range of motion, particularly internal rotation (8,10). Therefore, FAI can increase resistance to femoral internal axial rotation during a dynamic maneuver such as a pivot landing and cause ACL rupture (4).…”

Section: Introductionmentioning

confidence: 99%

Hip Restricted Range of Motion in Physical Examination: A Possible Risk Factor For Non-Contact ACL Injury

et al. 2015

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Background: There is significant evidence of hip and knee kinematic influence on each other. In some studies, hip restricted range of motion is a risk factor of anterior cruciate ligament (ACL) tear. Objectives: This study was designed to compare hip range of motion in physical examination between non-contact ACL injured patients with normal population. Patients and Methods: One hundred and forty patients with arthroscopically confirmed primary ACL ruptures were evaluated to assess their hip range of motion; these findings were compared with a control group of 100 patients with non ACL injury. Results: All parameters of hip range of motion (internal rotation, abduction and adduction) except external rotation were decreased significantly in ACL injured group compared with control group. Patients with sum of internal and external rotation lower than 80° had an increased odds ratio of having ACL injuries (OR = 2.64; 95% CI, 1.4 to 4.7). Conclusions: There was an association between non-contact ACL rupture and decreased hip range of motions including internal rotation, abduction and adduction as well as sum of internal and external rotation. Therefore, it may be possible to use hip physical exam finding as a predictor of ACL rupture.

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Femoroacetabular impingement and classification of the cam deformity: the reference interval in normal hips

Cited by 150 publications

References 26 publications

A perspective on femoroacetabular impingement

A perspective on femoroacetabular impingement

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

Hip Restricted Range of Motion in Physical Examination: A Possible Risk Factor For Non-Contact ACL Injury

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