Capital Growth Plate Research Articles

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 an open [corrected] 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. These findings suggest that 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.

The Cam-type Deformity of the Proximal Femur Arises in Childhood in Response to Vigorous Sporting Activity

The prevalence of a cam-type deformity in athletes and its association with vigorous sports activities during and after the growth period is unknown. We therefore compared the prevalence and occurrence of a cam-type deformity by MRI in athletes during childhood and adolescence with an age-matched control group. We retrospectively reviewed 72 hips in 37 male basketball players with a mean age of 17.6 years (range, 9-25 years) and 76 asymptomatic hips of 38 age-matched volunteers who had not participated in sporting activities at a high level. Eleven (15%) of the 72 hips in the athletes were painful and had positive anterior impingement tests on physical examination. Internal rotation of the hip averaged 30.1° (range, 15°-45°) in the control group compared with only 18.9° (range, 0°-45°) in the athletes. The maximum value of the alpha angle throughout the anterosuperior head segment was larger in the athletes (average, 60.5° ± 9°), compared with the control group (47.4° ± 4°). These differences became more pronounced after closure of the capital growth plate. Overall, the athletes had a 10-fold increased likelihood of having an alpha angle greater than 55° at least at one measurement position. Our observations suggest a high intensity of sports activity during adolescence is associated with a substantial increase in the risk of cam-type impingement. These patients also may be at increased risk of subsequent development of secondary coxarthrosis. Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Age-related force distribution at the proximal end of the femur in normally growing children

In a group of normally developed children and adolescents the age dependent distribution of forces at the proximal end of the femur was to be described. The results should explain why the shape of the proximal end of the femur changes significantly during the time of growth and why the neck shaft angle decreases. The method applied was the biomechanical computation analyzing in the coronal plane according to Pauwels' biomechanical hip model. The necessary age relevant data was derived from 675 anteroposterior pelvis radiographs of healthy children of both sexes and of varying age. The following can be put down as a result: 1. The proximal end of the femur is stressed by two resultant forces: the hip resultant force R controls the growth of the capital growth plate, the trochanteric resultant force RT regulates the growth of the greater trochanter growth plate. 2. During the growing period the hip resultant force R adjusts itself less vertically: during the second year of life it inclines at an average of 11,6 degrees towards the vertical, towards the end of the growing period it is incident with an inclination angle of 20 degrees. With the older child the magnitude of the hip resultant force R decreases in relation to the exerting body weight. 3. During the time of growth the trochanteric resultant force RT maintains its direction stability with inclination angles of 50-52 degrees towards the vertical. Its magnitude increases significantly (in relation to the exerting body weight). 4. From age 2 to 10 the projected neck shaft angle decreases from an average of 148.2 degrees to 133.7 degrees and usually remains stable. It can be concluded that the shape of the proximal end of the femur is determined by the muscle forces stimulating the greater trochanter apophysis and by gravity. With increasing age the growth of the greater trochanter apophysis shifts the insertions of abductor muscles laterally. As a result the directions of the hip abductors and the hip resultant force R incline. The neck shaft angle decreases consecutively.

Tensile properties of the physis vary with anatomic location, thickness, strain rate and age

The variable outcome of physeal distraction has raised questions as to the mechanism by which bone lengthening is achieved. Is it by stretching of the matrix or does it stimulate growth? In order to explore the contribution of matrix stretching, we sought to answer the following questions in an animal model: (a) Are the tensile properties of the lateral side of the proximal tibial physis different from the medial? (b) Are the tensile properties strain-rate dependent? (c) Does the growth plate fracture through any preferred zone in tension? (d) Are the tensile properties of the bovine growth plate a function of age? (e) Are thicker growth plates weaker in tension? (f) Are the tensile properties of the bovine growth plate comparable to those of a child's? We compared bone–cartilage–bone specimens (0.5×2.5 mm 2 in cross-section) from the lateral, central and medial regions of the proximal tibial growth plates of 12- to 18-month heifers. 70 specimens were tested to failure in tension at 0.0004, 0.004 and 0.04 mm/s. Tensile strength and tangent modulus were 33% and 25% greater, respectively, on the lateral side compared with the medial, and both were increased at the higher strain rates. We found no difference in the ultimate strains by region or strain rate. Thicker growth plates were weaker. Scanning electron microscopy revealed a three-dimensional fracture pattern extending from the upper columnar into the reserve zone. Bundles of intact chondrons remained intact, but only on the metaphyseal side, having been torn from an interterritorial matrix which remained mostly on the epiphyseal side of the fracture. We compared 21 specimens of 12- to 18-month and 19 specimens of 5-month calves from similar regions of the proximal tibia. These were tested to failure in tension at 0.004 mm/s. The older bovine growth plate was 25% thinner, 34% stronger and failed at 65% greater strain. For comparison, we tested eight samples from the femoral capital growth plate of two cerebral palsy patients. These were twice as thick as our bovine samples and about half as strong, but with similar ultimate strain values.

Trochanteric advancement for premature arrest of the femoral capital growth plate: G.C. Lloyd-Roberts, M.H. Wetherill and M. Fraser. J Bone Joint Surg 67B:21–24, (January), 1985

Trochanteric advancement for premature arrest of the femoral capital growth plate: G.C. Lloyd-Roberts, M.H. Wetherill and M. Fraser. J Bone Joint Surg 67B:21–24, (January), 1985

Trochanteric advancement for premature arrest of the femoral capital growth plate.

Premature closure of the growth plate of the femoral capital epiphysis associated with limitation of abduction and gluteal insufficiency is described. The indications for trochanteric advancement and the results obtained in the late treatment of Perthes' disease and of congenital dislocation are discussed. Nine hips treated after Perthes' disease had satisfactory results, in that all were improved; but in eight hips with deformity arising from congenital dislocation the outcome was less favourable.

Coxa plana--the fate of the physis.

Eighty patients who had unilateral coxa plana and who had been treated conservatively were followed to a mean age of sixteen and one-quarter years, and their cases were reviewed for radiographic evidence of a disturbance of the femoral capital growth plate. This physeal involvement was inferred by the presence of one or more of five findings: premature physeal closure, overgrowth of the greater trochanter, change in physeal shape, lateral protrusion of the capital nucleus, and medial bowing of the femoral neck. Premature physeal closure, which was more common in the girls than in the boys, occurred in 25 per cent of the affected femoral heads, and 90 per cent of the patients showed some interference with normal physeal growth in the affected femoral head. A direct correlation was found between the severity of the physeal involvement and the ultimate deformity of the femoral head. The possible causes of interference with physeal growth and damage are discussed.

Changes in the Capital Growth Plate and the Proximal Femoral Metaphysis in Legg-Calvé-Perthes Disease

Studies on about 350 hips treated during the years from 1946 to 1965 for Legg-Calvé-Perthes disease (LCPD) showed that metaphyseal changes regularly appear in this condition. When these changes are extreme, a step-like irregularity appears in the capital growth plate and the bony epiphysis adapts itself to the metaphyseal defect. This phenomenon of step-like progression of changes in the growth plate is seen in other conditions as a consequence of cartilage necrosis. When premature closure of the capital epiphyseal plate occurs in LCPD it may be followed by "overgrowth" of the greater trochanter and a positive Trendelenburg sign. This functional disability may be prevented by apophyseodesis of the greater trochanter if it is performed early enough.