Subpectoral biceps tenodesis: an anatomic study and evaluation of at-risk structures.

BACKGROUND

The neurovascular structures of the proximal arm may be at risk for iatrogenic injury during open subpectoral biceps tenodesis (OSPBT).

PURPOSE

To define the anatomic relationships and at-risk structures during OSPBT and to quantify the effect of arm rotation on the position of the musculocutaneous nerve.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The OSPBT approach was performed in 17 unembalmed cadaveric upper extremities. The tenodesis site was inferior to the bicipital groove and positioned so the musculotendinous portion of the long head of the biceps rested at the inferior border of the pectoralis major. A meticulous dissection identified the brachial artery, deep brachial artery, cephalic vein, brachial vein, medial brachial cutaneous nerve, medial antebrachial cutaneous nerve, intercostal brachial cutaneous nerve, musculocutaneous nerve, axillary nerve, median nerve, and radial nerve. Superficial structures were measured from the superior and inferior aspects of the incision, and deep structures were measured from the tenodesis site and nearest retractor. The musculocutaneous nerve was measured with the arm in neutral, internal, and external rotation.

RESULTS

The musculocutaneous nerve was 10.1 mm (range, 6-18 mm) medial to the tenodesis location and 2.9 mm (range, 1-6 mm) medial to the medially placed retractor in neutral arm position. The radial nerve and deep brachial artery were 7.4 mm (range, 2-12 mm) and 5.7 mm (range, 1-10 mm) deep to the medially placed retractor, respectively. With the arm internally rotated to 45°, the musculocutaneous nerve was 8.1 mm from the tenodesis site, compared with 19.4 mm with the arm 45° externally rotated (P = .009). The median nerve, brachial artery, and brachial vein were >2.5 cm from the tenodesis site and nearest retractor during deep dissection.

CONCLUSION

The musculocutaneous nerve, radial nerve, and deep brachial artery are within 1 cm of the standard medial retractor. External rotation of the arm moves the musculocutaneous nerve 11.3 mm further away from the tenodesis site compared with the internally rotated position.

CLINICAL RELEVANCE

The musculocutaneous nerve, radial nerve, and deep brachial artery course in close proximity to the operative field and are therefore at risk during OSPBT. Limiting the use of medial retraction and placement of the arm in an externally rotated position will minimize neurovascular injury.