Variations of extensor pollicis brevis tendon in Indian population: A cadaveric study and review of literature.

Objectives: Variations of the tendons of the first dorsal compartment of the wrist may be one of reasons of treatment failure and recurrence in De Quervain's tenosynovitis (DQT). The present cadaveric study was designed to look into the variations of the Extensor pollicis brevis (EPB) tendon in Indian population.

Methods: Seventy-seven formaldehyde-fixed cadaveric upper limbs of Indian origins were dissected to observe the number of EPB tendons and its variations.

Results: The EPB muscle was found to be absent in one hand (1.3%). The EPB muscle was found with single tendon, two tendons and three tendons in 73 limbs (94.8%), 2 limbs (2.6%) and one limb (1.3%) respectively. The muscle originated from the posterior surface of the radius and the adjacent interosseous membrane. The EPB muscle with single tendon was found to be inserted into the distal part of dorsal surface of the proximal phalanx of the thumb in 44 limbs (57.1%). In limbs with bitendinous EPB, the tendon slips were inserted into the base of proximal phalanx and into the base of distal phalanx of the thumb. An Osseo-fibrous septum separating EPB from Abductor Pollicis Longus (APL) was observed in 45 limbs (58%).

Conclusion: EPB in first extensor compartment of Indians is usually monotendinous. It mostly inserts into the distal part of dorsal surface of proximal phalanx of thumb and into the base of distal phalanx. In majority of the wrists, one may find an osseofibrous ridge separating EPB from APL. These anatomical variations may be helpful to guide proper treatment in de Quervain's tenosynovitis.