Congenital absence of the long head of biceps tendon & its clinical implications: a systematic review of the literature.

Background: Multiple reports of congenitally absent long head of biceps tendon (LHBT) have been reported in the literature. However, there is no consensus on the clinical implications of this relatively rare entity.

Study Purpose: To systematically review and analyze all studies which have reported absence of LHBT.

Methods: PubMed and EMBASE databases were searched. Also, a secondary search was performed by pearling the bibliography of all the full-text articles obtained. Pre defined inclusion criteria was used for abstract screening by two independent observers. Twenty three studies met our inclusion criteria, were included for the final analysis and the data was pooled. The cases were further sub-grouped according to the classification of Dierickx et al.

Results: Till date, 35 cases of absent LHBT have been reported. Males and females were equally affected. Eight of these were bilateral and only four cases had other associated congenital anomalies. Majority of the patients presented with shoulder pain (85.7%) while 37.1% had shoulder instability (mainly anterior instability). The ABS type was the most common variant reported. The finding was missed in 60% of the cases on the initial MRI only to be detected later on shoulder arthroscopy.

Conclusions: Congenitally absent LHBT may not be as rare as was previously thought to be. Due to the heterogeneity and the low level of evidence of the data available, it is hard to conclude if a congenitally absent LHBT is a cause of shoulder pain/impingement or instability on its own.

Level of evidence: IV.