The distal biceps tendon. Two potential mechanisms involved in its rupture: arterial supply and mechanical impingement.

The purpose of this anatomic study was to evaluate potential causes of rupture of the distal biceps tendon, to assess the dynamic relationship of the proximal radioulnar joint during pronation and supination, and to identify potential sites of impingement of the distal biceps tendon. For the anatomic study specimens were evaluated by light microscopy, multiplanar gross dissections, and Spalteholz vascular injection. For the radiographic study computed tomography was used to assess dynamic changes in the radioulnar space in pronation, neutral position, and supination. Three vascular zones were identified in the distal biceps tendon. Vascular contributions were consistently noted from the brachial artery proximally and from the posterior recurrent artery distally. A hypovascular zone averaging 2.14 cm was evident between the proximal and distal zones. On sectioning through the proximal radioulnar joint 85% of the space was occupied by the distal tendon in full pronation. In addition, computed tomography imaging revealed a 50% reduction in the radioulnar joint at the radial tuberosity from full supination to full pronation. Mechanical impingement on the biceps tendon during forearm rotation and hypovascularity within sections of the tendon may contribute to attritional ruptures of the distal biceps tendon.

The blood supply to the great toe sesamoids.

The purpose of this study was to define the intraosseous and extraosseous blood supply of the hallucal sesamoids by studying a total of 10 fresh-frozen, below-knee specimens with no evidence of vascular disease. Most specimens were injected with high grade India ink, cleared using a standard Spalteholz technique, and processed to delineate the extraosseous and intraosseous blood supply to include soft tissue dissection and coronal sectioning. Two additional specimens were injected with blue Mercox acrylic solution to further define the extraosseous vasculature. The major extraosseous blood supply to the sesamoids is via the posterior tibial artery. This vessel then branches into the medial plantar artery which further divides upon entering the medial and lateral sesamoids in their proximal poles. Vessels in the peripheral soft tissues, although abundant, do not seem to penetrate the cortex of the sesamoids. The intraosseous blood supply to the sesamoids seems to be threefold. Mainly, sesamoid arteries enter the lateral and medial sesamoids from the proximal aspect via a single vessel. This proximal vessel proceeds distally with a network of branching. Plantar, nonarticular vessels enter the sesamoids, constituting a second source of vascularity. Finally, small vessels also enter the sesamoids through medial and lateral capsular attachments. Based on this study, a possible explanation for avascular necrosis and nonunion of sesamoids is proposed, and an optimal surgical approach is discussed.(ABSTRACT TRUNCATED AT 250 WORDS)