Monday, February 21, 2011

Basketball effect on bone morphology

A cam deformity is an excess of bone along the upper surface of the femoral head.  It's unclear how this may affect height.

Growth Plate Alteration Precedes Cam-type Deformity in Elite Basketball Players.

"Vigorous sporting activity during the growth years is associated with an increased risk of having a cam-type deformity develop. The underlying cause of this osseous deformity is unclear. One may speculate whether this is caused by reactive bone apposition in the region of the anterosuperior head-neck junction or whether sports activity alters the shape of and growth in the growth plate. If the latter is true, then one would expect athletes to show an abnormal shape of the capital growth plate (specifically, the epiphyseal extension) before and/or after physeal closure.
We therefore raised three questions: (1) Do adolescent basketball players show abnormal epiphyseal extension? (2) Does the epiphyseal extension differ before and after physeal closure? (3) Is abnormal epiphyseal extension associated with high alpha angles?
We performed a case-control comparative analysis of young (age range, 9-22 years) male elite basketball athletes with age-matched nonathletes, substratified by whether they had open or closed physes. We measured epiphyseal extension on radial-sequence MRI cuts throughout the cranial hemisphere from 9 o'clock (posterior) to 3 o'clock (anterior). Epiphyseal extension was correlated to alpha angle measurements at the same points.
Epiphyseal extension was increased in all positions in the athletes compared with the control group. On average, athletes showed epiphyseal extension of 0.67 to 0.83 versus 0.53 to 0.71 in control subjects. In the control group epiphyseal extension was increased at all measurement points in hips after physeal closure compared with before physeal closure. In contrast, the subgroup of athletes with a closed growth plate only had increased epiphyseal extension at the 3 o'clock position compared with the athletes with a closed growth plate (0.64-0.70). We observed a correlation between an alpha angle greater than 55° and greater epiphyseal extension in the anterosuperior femoral head quadrant: the corresponding Spearman r values were 0.387 (all hips) and 0.285 (alpha angle > 55°) for the aggregate anterosuperior quadrant.
A cam-type abnormality in athletes is a consequence of an alteration of the growth plate rather than reactive bone formation. High-level sports activity during growth may be a new and distinct risk factor for a cam-type deformity."

"an increased incidence of the tilt deformity in adolescents [occurs] with compulsory sporting activity when compared with adolescents without compulsory sporting activity (24% versus 9%). "

"Increased extension of the physeal cartilage onto the metaphysis has been associated with abnormal growth of the femoral head in Perthes disease"

"(A) A radial-sequence MR image of the hip of a 20-year-old basketball player taken at the 2 o’clock position is shown. (B) The diameter (d) of the femoral head, through the center of the head-neck axis, and the distance from a line orthogonal to the diameter to the lateral-most extension of the epiphysis (e) is measured. The epiphyseal extension is defined as e/d. (C) The measurement of the alpha angle on this same MRI slice is shown."

"Athletes had greater epiphyseal extension than control subjects at all positions"

"When comparing subgroups, there was a marked increase in epiphyseal extension in athletes with open physes compared with control subjects. After physeal closure, epiphyseal extension remained greater in athletes compared with control subjects; however, the difference between the two groups was reduced"

"although we detected an altered physeal shape in athletes, the ultimate impact on morphologic features of the proximal femur and subsequent joint function remains unclear."

"One may speculate whether this pattern represents irregular growth velocity or early focal physeal closure. Early physeal arrest has been described predominantly in the upper extremities of overhead throwing athletes"

Editor's Spotlight/Take 5: Growth Plate Alteration Precedes Cam-type Deformity in Elite Basketball Players (DOI 10.1007/s11999-012-2740-6)

"An increased prevalence for cam-type morphologic features in adolescents is not unique for basketball players. It has been described for various kinds of sports including soccer, ice hockey, running, and other activities. High-impact activities of various kinds seem to affect the developing proximal femur. I would be very surprised if intensity level does not also play an important role. I believe it is likely a combination of impact and intensity that are responsible for the changes. The most important issue to me, however, is the time over which changes to the growth plate were detected. Alteration of the physeal extension occurred between the ages of 9 and 16 years, while the growth plate was still open."

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