We describe the in-vivo length and diameter of the long head biceps tendon at the time of a subpectoral biceps tenodesis.
Subpectoral biceps tenodesis (SPBT) has gained popularity. One concern is that tunnel placement in the diaphyseal or metaphyseal-diaphyseal portion of the humerus can act as a stress riser for fractures. We sought to determine whether, age, gender, height, weight, and body mass index had an affect on tendon length and diameter, to predictably determine the smallest possible tunnel diameter for SPBT.
Materials And Methods
Following power analysis, 66 patients (33 males) with an average age of 54 (range 29-73 years) undergoing shoulder arthroscopy and SPBT were included, with minimum follow up of 2 years. The tendon was released at the biceps-labrum junction and its length from the musculotendinous junction (MTJ) to the released portion was measured. The tendon was transected 3 cm proximal to the MTJ, sutured, and the diameter measured. The anterior cortex was reamed over a bicortical guidewire, and tunnel depth was recorded. Post-operative radiograph was used to measure the distance of the tunnel from the humeral head.
Average tendon length was 84.0mm, 91.9mm in males and 76.2mm in females (p<0.01), and average tendon diameter was 4.4mm, varying slightly between males (4.5mm) and females (4.3mm) (p<0.01). Mean bone tunnel depth was 17.5mm, and was 19mm in males and 16.1mm in females (p<0.01). Patient height demonstrated a significant relationship to both tendon length and tendon diameter. Weight was not correlated with tendon diameter, but did show a significant relationship with tendon length. There were no infections, nerve complications, or fractures in this cohort of patients.
This is the first study to measure the in vivo length and diameter of the long head biceps tendon at the time of a SPBT. Our findings show that there is a statistically significant gender difference in tendon length and diameter. However, the sutured tendon diameter, which is placed into the tunnel, averaged 4.4 mm and ranged from 3.5mm to 5 mm for all age, gender, height, and weight.