Spectrum of Radiographic Femoroacetabular Impingement Morphology in Adolescents and Young Adults: An EOS-Based Double-Cohort Study

Abstract

There was a high prevalence of radiographic impingement morphology beyond the spectrum of normal in this double-cohort study of adolescents. Femoroacetabular impingement remains a dynamic problem, and we caution against relying only on the use of hard-set static radiographic parameters when evaluating femoroacetabular impingement. This study raises the important question of what morphologic characteristics should be defined as abnormal, when at least one finding of impingement morphology is noted in such a large segment of the population. On the basis of the normative data obtained, reference values for radiographic parameters of femoroacetabular impingement morphology should be redefined. Normal values for a Tönnis angle were between -8° and 14°, the upper limit of the center-edge angle was 44°, and the normal values for femoral neck-shaft angle were between 121° and 144°. Surgical indications should be tailored to physical examination findings and not radiographic findings alone.

Prevalence of Femoroacetabular Impingement Morphology in Asymptomatic Adolescents

“…An abnormal AP a-angle was noted in 5.6% of males and 6.7% of females, and was significantly more common in the adolescents without scoliosis. 8 Carsen and colleagues reported cam morphology exclusively in adolescents with closed physes. None of the subjects in their prephyseal closure group had elevated a-angles on MRI, whereas 14% of their closed physeal group had elevated a-angles and all were male.…”

“…[4][5][6] Few studies have examined the prevalence of FAI morphology in the asymptomatic pediatric population. [7][8][9] While some studies reported cam morphology in children as young as 10 years and pincer morphology in children as early as 12 years of age, 7 other studies demonstrated cam morphology exclusively in adolescents with closed physes. 9 The pathogenesis of FAI is unclear.…”

“…[7][8][9] Monazzam and colleagues reported cam morphology in 10.2% of males and 2.5% of females on CT evaluation. Cam and pincer morphologies were seen in children as early as 10 and 12 years of age, respectively.…”

Treatment of Arthritis Associated With Legg–Calve–Perthes Disease With Modular Total Hip Arthroplasty

“…Ischemic necrosis mechanically weakens the femoral head and subsequent mechanical loading contributes to the femoral head deformity 4 and ultimately alteration in growth of the femoral bone 3,5 . Acetabular changes similar to development dysplasia often accompany femoral remodeling 3,6 . In some cases, secondary arthritis ensues regardless of management 3,7,8 .…”

Lower extremity overuse injuries in the skeletally immature athlete

“…Care should be taken in interpreting these images, however, because in one recent study of adolescents without hip problems, 93% of hip radiographs showed at least one parameter suggestive of impingement. 12 Therefore, in the absence of hip pain, such findings are not necessarily pathologic. For patients with hip symptoms and radiographic findings of impingement, a magnetic resonance arthrogram should be obtained to assess associated injuries to the labrum or articular cartilage.…”