Decreased range of motion is associated with structural hip deformity in asymptomatic adolescent athletes.

BACKGROUND

Decreased hip range of motion (ROM) is a common finding in patients with femoroacetabular impingement (FAI).

PURPOSE

To report the prevalence of decreased hip ROM in asymptomatic adolescent athletes and to correlate examination findings to signs of FAI on radiographs and magnetic resonance imaging (MRI).

STUDY DESIGN

Cross-sectional study (prevalence); Level of evidence, 3.

METHODS

A total of 226 adolescent athletes presenting for state-mandated preparticipation physical examinations were assessed. Hip internal rotation was measured with the participant supine and the hip flexed to 90°. All participants with ≤10° of internal rotation were invited to return for standard radiographs and MRI of both hips. An age-matched control group, with >10° of internal rotation, underwent MRI examination only. Twenty-six athletes (13 study and 13 control) returned for clinical and radiographic examinations.

RESULTS

Nineteen athletes (34 hips, 8%) were found to have <10° of internal rotation. Eight athletes (13 hips, 3%) also had a positive anterior impingement sign. Thirteen of 19 athletes participated in the radiographic portion of the study. Of these 13 participants, 4 had limited internal rotation unilaterally, leaving 22 hips in the study group. Eight of 13 participants (15 hips, 68%) had a cam-type deformity evident on plain radiographs, and 4 participants (7 hips, 32%) had a positive radiographic crossover sign. The average α angle measured from radial MRI sequences was 58.1° in the study group versus 44.3° in the control group (P < .001). Fifteen hips (68%) in the study group had abnormal MRI findings within the acetabular labrum or cartilage compared with 10 of 26 hips (38%) in the control group (odds ratio, 3.4; P = .078).

CONCLUSION

Eight percent of asymptomatic teenagers had limited internal rotation on examination; 68% of these had radiographic findings suggestive of FAI. More than two thirds of these participants had evidence of asymptomatic hip pathological lesions on MRI.