MR imaging of capitellar ossification: a study in children of different ages

Abstract

Capitellar ossification is an eccentric process, with lag in anterior-posterior centralization in boys. Medial offset persists at 12-13 years. Recognition of this eccentric ossification may allow for more accurate assessment of elbow alignment on radiographs, especially in younger children.

Eccentric Capitellar Ossification Limits the Utility of the Radiocapitellar Line in Young Children

“…The appearance of ossification centers in the elbow and their relationship to age are well documented [4][5][6]23 ; however, the ossification pattern of the capitellum has not been reported in detail until recently. 7 Our results demonstrate that the precision of the RCL is limited at younger ages by the eccentric pattern of capitellar ossification. The RCL intersected with the middle third of the cartilaginous capitellum in nearly all patients at all ages but did so far less reliably with the central third of the ossified capitellum.…”

“…Most patients included in this study were subjects for a previous publication. 7 Seven patients from the prior cohort were excluded due to acute radiocapitellar malalignment, and 8 new patients were identified.…”

“…2,3 In addition, the dynamic ossification of structures within the elbow joint during skeletal maturation makes standardized radiographic evaluation in children problematic. [4][5][6][7] The radiocapitellar line (RCL), first described by Storen in 1959, 8 is a line drawn along the radius that is expected to intersect the capitellum on lateral radiographs of a normal elbow. [8][9][10][11][12] Storen 8 initially applied the RCL to lateral projections only and did not specify whether the line was drawn down the radial neck 13,14 or shaft.…”

“…However, Fader et al, 7 using magnetic resonance imaging (MRI), recently reported that the capitellum ossifies eccentrically, similar to the ossification pattern of the talus, calcaneus, and navicular bones of the foot, 20 and is not centrally located within the cartilaginous capitellum in the sagittal view until 12 to 13 years of age. 7 We suggest that these findings likely form the basis for previous studies that have shown that the RCL was notably less reliable in younger patients. Alternatively, subtle global joint laxity, which is more common in younger children, 21,22 could be responsible for this inaccuracy.…”

The carrying angle: racial differences and relevance to inter-epicondylar distance of the humerus

“…It has been well established that the capitulum and medial epicondyle are formed much earlier than the trochlea during growth [9,17,19]. Furthermore, as the capitulum ossifies, it grows more medially and crosses the border of the proximal radioulnar joint toward the trochlear space [10], leaving a limited space for the trochlea to develop later on. As the trochlea ossifies, it will grow farther distally in order to compensate for the space shortage, thereby contributing to the formation of the CA.…”