Physiologic Long Head Biceps Tendon Excursion Throughout Shoulder Range of Motion: A Cadaveric Study

Area of Science:

• Orthopedic surgery
• Biomechanics
• Anatomy

Background:

• Restoring the long head of the biceps tendon (LHBT) length-tension relationship is critical for preserving muscle strength and efficiency during biceps tenodesis.
• Shoulder position is a variable that may affect biceps tendon excursion, influencing surgical outcomes.

Purpose of the Study:

• To quantitatively evaluate the normal excursion of the LHBT throughout the glenohumeral range of motion.
• To determine if elbow position affects LHBT excursion.
• To test the hypothesis that glenohumeral flexion/extension and elbow extension influence LHBT excursion.

Main Methods:

• A controlled laboratory study using 10 fresh-frozen shoulder specimens.
• The LHBT was identified and tagged; K-wires were used to measure excursion via fluoroscopic imaging across 8 different shoulder positions.
• Data were analyzed using ANOVA and Tukey's honestly significant difference tests.

Main Results:

• Average total LHBT excursion was 24.4 ± 5.2 mm across tested positions.
• LHBT position significantly differed between the reference position and other tested positions (P < .001).
• Shoulder extension positions showed different LHBT excursions compared to flexion positions (P < .0001); elbow position did not significantly affect excursion.

Conclusions:

• Approximately 24 mm of LHBT excursion occurs throughout the glenohumeral range of motion.
• Shoulder positioning significantly affects LHBT excursion, with extension and flexion differing from neutral.
• Elbow position does not significantly impact LHBT excursion, but shoulder extension may lead to overtensioning, and flexion to undertensioning.