Cam deformities and limited hip range of motion are associated with early osteoarthritic changes in adolescent athletes: a prospective matched cohort study

In recent years the syndrome of femoroacetabular impingement of the cam or pincer type has been extensively discussed in the literature. We now know very well that femoroacetabular impingement can be a cause of chronic pain, especially in active adults and in sporting individuals generally. What has still not been clarified is the relationship between femoroacetabular impingement and osteoarthritis. There is a good deal of evidence in the literature that femoroacetabular impingement is a precursor stage to the early development of osteoarthritis, especially in athletically active individuals. However, this theory has not been fully proved.
The natural history of femoroacetabular impingement is still poorly understood. It is not entirely known whether it causes a limited range of hip motion or whether the reverse is the case, and the way in which it may cause damage to the hip joint is not yet understood.
A recently published study in the American journal “American Journal of Sports Medicine” set out to assess the changes on magnetic resonance imaging, on radiographs and on clinical assessment over five years in a group of athletes from a wide range of sporting activities who had an asymptomatic hip but a limited range of motion, compared with a control group. This publication was a cohort study and was level II evidence.
The authors screened 226 male and female athletes aged 12 to 18 years, who were assessed clinically. Using a goniometer, 13 athletes were identified with at least one hip having external rotation < 10° with the hip flexed to 90°. In all, 21 of the 26 hips had internal rotation < 10°. The participants in the study were compared with 13 individuals in the control group with internal rotation > 10°. At the time of the study all the participants were asymptomatic and underwent a full examination of the hip and radiological assessment with plain radiographs and with magnetic resonance imaging. The participants returned at five years and underwent further assessments, both clinical and imaging (plain radiographs and magnetic resonance imaging), and questionnaires on hip function. The magnetic resonance scans were classified as normal or abnormal on the basis of the presence of abnormalities involving either the labrum or the articular cartilage, or bony deformities. The results and the comparisons were obtained using statistical methods.
During the study, 16 of the 26 hips with a limited range of motion had abnormal findings on magnetic resonance imaging in the articular cartilage or the labrum, compared with 8 of the 26 hips in the control group. The mean alpha angle measured on magnetic resonance imaging was 58° in the group with a limited range of motion, against 44° in the control group. In the limited-motion group, 13 of the 26 hips had a positive anterior impingement sign, as against none of the 26 hips in the control group. At the five-year review, 18 of the 19 hips in the group with a limited range of motion had abnormal findings on magnetic resonance imaging, compared with 14 of the 26 hips in the control group. New or progressively worsening findings were recorded on the magnetic resonance scans in 15 of the 20 hips in the group with a limited range of motion, compared with 8 of the 26 in the control group. 6 of the 22 hips in the limited-motion group progressed from Tonnis grade zero to Tonnis grade one degenerative change, while all 26 hips in the control group remained at Tonnis grade zero on all the plain hip radiographs. In the limited range of motion group, 11 of the 22 hips had a positive anterior impingement sign, while 1 of the 26 hips had such a positive test in the control group.
A cam deformity was present in 22 of the 22 hips in the group with a limited range of motion and in 12 of the 26 hips in the control group. The following parameters were also associated with an increased risk of degenerative change at five years for the whole cohort: reduced internal rotation of the hip, a positive anterior impingement sign, reduced hip flexion, an increased alpha angle and the presence of a cam-type lesion.
The authors concluded that at five years the young athletes with a limited range of hip motion showed increased progressive degenerative changes on magnetic resonance imaging and on radiographs compared with the control group. Although the majority of the participants remained asymptomatic, those with features of femoroacetabular impingement had radiological findings consistent with early osteoarthritis. These results suggest that more aggressive screening is needed, as well as counselling of young, athletically active patients, which may be useful in preventing hip osteoarthritis in individuals with femoroacetabular impingement.
Source: Wyles CC, Norambuena GA, Howe BM, Larson DR, Levy BA, Yuan BJ, Trousdale RT, Sierra RJ. Cam Deformities and Limited Hip Range of Motion Are Associated With Early Osteoarthritic Changes in Adolescent Athletes: A Prospective Matched Cohort Study. Am J Sports Med. 2017.