Humeral Capitellum

Takahara M, Mura N, Sasaki J, Harada M, Ogino T (2007) Classification, treatment, and outcome of osteochondritis dissecans of the humeral capitellum. J Bone Joint Surg Am 89 1205-1214... 

The bone structures about the elbow joint include the proximal ends of the ulna and radius and the distal end of the humerus (Fig. 8.1). The radial head articulates with the humeral capitellum in a pivotal mode and the ulna with the humeral trochlea in a hinge mode. The proximal radio-ulnar articulation is composed of the radial head which revolves within the sigmoid (radial) notch of the ulna allowing pronation-supination movements. These articulations cooperate during complex joint movements allowing a wide degree of flexion, extension and axial... 

Fig. 8.13a,b. Median nerve and brachial artery. Longitudinal gray-scale (a) and color Doppler (b) 12-5 MHz US images over the antecubital fossa demonstrate the normal appearance of the median nerve (white arrows in a) and the brachial artery (open arrows in b). Both lie superficial to the brachialis muscle (hr). Note the humeral capitellum (HC) and the radial head (RH). The inserts at the upper left side of the figures indicate probe positioning... 

In pulled elbow , a common injury among children due to slipping of the annular ligament over the radial head following forceful pronation, US is able to depict an increased distance between the radial head and the humeral capitellum probably due to the impingement of the annular ligament (Kosuwon et al. 1993) - see also chapter 19. 

Fig. 8.74a-d. Occult fracture of the right coronoid process in a woman following a ski accident, a The patient had a negative radiographic examination performed soon after the injury, b Two weeks later, she was submitted to US examination due to persistent elbow pain and loss of extension. US identified an interruption (curved arrow) of the hyperechoic cortical profile of the coronoid process (C), just cranial to the insertion of the brachialis (br). There was associated mild intra-articular effusion. HC, humeral capitellum. c Left healthy side for comparison, d Additional oblique view of the right elbow confirms the fracture... 

Fig. 18.1a-g. Serial radiographs of the elbow showing the typical sequence of the appearance of the ossification centres, a No ossified centres b capitellum c radial head d internal (medial) humeral apophysis e trochlea f olecranon and g external (lateral) humeral apophysis... 

Clinical examination reveals a laterally swollen elbow, tender at the fracture site, which is increased by active flexion of the wrist. Interpretation of the AP and lateral radiographs depend on the degree of ossification of the capitellum and the extent of the displacement. The lesser the degree of ossification, the harder it is to assess the fidl extent of the injury. In infants, where there is no ossification of the distal humeral epiphysis, lateral condylar injury may be confused with physeal separation or dislocation of the joint Physeal separation is the conunonest of these injuries in infants less than 1 year old. Often the only sign of injury is a small sliver of displaced metaphyseal bone. 

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