Shoulder pain related to biceps-labrum complex disease is frequently encountered. Open sub-pectoral biceps tenodesis is a popular surgical technique to address refractory symptoms. Restoration of physiologic length-tension relationships may be important to achieve optimal outcomes. Others have reported on static anatomic landmarks that can be used intraoperatively to establish anatomic length-tension relationship. The purpose of this study was to evaluate the normal excursion of the long head of the biceps tendon that occurs throughout a range of motion and its implications during biceps tenodesis.
Materials And Methods
Ten cadaveric forequarter specimens including scapula and forearm without known history of shoulder pathology were evaluated. A standard open subpectoral approach to long head of biceps tendon was performed on each specimen and the long head of biceps tendon was tagged with a circular radio dense marker at the musculotendinous junction. Three 0.62 K-wires were drilled into the bicipital tunnel osseous floor 2 cm apart. The K-wires were cut flush with the anterior humeral cortex. The specimens were then brought into eight different positions (4 different shoulder positions 30 degrees extended, neutral, 45 degrees forward flexed, 90 degrees forward flexed – each with 2 different elbow positions 90 degrees flexed and extended). Radiographs were taken with the arm in each position and used to determine biceps excursion relative to a neutral position. The results were then analyzed for significance using a one-way ANOVA test followed by Turkey HSD test.
With the shoulder in 30 degrees of extension and the elbow flexed the long head of the biceps tendon demonstrated 9.36 ± 4.11 millimeters (mm) of proximal excursion (p < 0.01) and with the shoulder in the same position and the elbow extended the tendon demonstrated 9.14 ± 7.02 mm of proximal excursion (p < 0.01). With the shoulder in 45 degrees of forward flexion and the elbow flexed the tendon demonstrated 5.25 ± 6.16 mm of distal excursion (p = 0.29) and with the shoulder in the same position and the elbow extended the tendon demonstrated 7.64 ± 5.82 mm of distal excursion (p < 0.05). With the shoulder in 90 degrees of forward flexion and the elbow flexed the tendon demonstrated 8.46 ± 3.81 mm of distal excursion (p < 0.05) and with the shoulder in the same position and the elbow extended the tendon demonstrated 10.37 ± 3.43 mm of distal excursion (p < 0.01). With the shoulder in 90 degrees of forward flexion and abducted 45 degrees the tendon demonstrated 11.59 ± 6.04 mm of distal excursion (p < 0.01).
ANOVA results demonstrate a significant difference for six of the seven different arm positions. The only non-significant difference was with the shoulder forward flexed to 45 degrees with the elbow flexed, however this position trended towards a significant difference.
Approximately two centimeters of biceps tendon excursion occurs throughout a normal shoulder range of motion. Understanding the physiologic amount of biceps excursion with the arm in different positions may aid in restoring a more appropriate length-tension relationship.