Radial Tuberosity

Several synovial bursae around the elbow joint lessen friction between bones and the overlying skin and soft-tissue structures. The most important are the olecranon bursa and the bidpitoradial bursa. The olecranon bursa is a large subcutaneous bursa which intervenes between the skin and the olecranon process over the posterior aspect of the elbow. The bidpitoradial bursa (cubital bursa) lies deep in the anterior compartment of the elbow, between the distal biceps tendon and the radial tuberosity, to reduce friction between, especially during pronation of the forearm (Skaf et al. 1999). In fact, the radial tuberosity rotates posteriorly during pronation and wraps the tendon around the radial cortex. During this movement, the bursa is tracked between the tendon and the bone (Fig. 8.8). When distended by fluid, the bicipitoradial bursa may surround the biceps tendon completely and may cause a mass effect on the adjacent branches of the radial nerve. 

Fig. 8.8a-c. Bicipitoradial bursa. a,b Schematic drawings illustrate the position of the bicipitoradial bursa (asterisks) relative to the distal biceps tendon (T) during a supination and b pronation. In pronation, the long axis of the radius (R) and the radial tuberosity (star) rotate compressing the bursa between the distal biceps tendon (T) and the bone. U, ulna. (Drawings modified by Skaf et al. 1999.) c Skeletal model showing the relationship of the bicipitoradial bursa (asterisk) with the distal biceps tendon (T) in full pronation. Note the posterior and lateral position of the radial tuberosity (star) onto which the biceps tendon inserts... 

Surgical treatment in complete tendon tears includes repair and reattachment of the retracted tendon to the radial tuberosity or, alternatively, to the brachialis muscle or the ulnar tuberosity. The first technique gives better results in restoring supination but has a significantly higher risk of radial nerve injury. After surgery, the tendon appears thickened and hypoechoic with internal linear hyperechoic images related to sutures (Fig. 8.31). 

Fig. 8. 30a-d. Partial rupture of the distal biceps tendon, a Long-axis and b short-axis 12-5 MHz US images obtained at level distal to the elbow joint with c, d correlative transverse Tlw SE MR images demonstrate a thickened and heterogeneous tendon (arrows) inserting on the radial tuberosity (asterisk)... 

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