Extensor pollicis brevis tendon can hyperextend thumb interphalangeal joint in absence of extensor pollicis longus:Case report and review of the literature

We are reporting a case of extensor pollicis longus tendon rupture which did not require tendon transfer owing to the ability of the intact extensor pollicis brevis(EPB) to fully hyperextend the thumb interphalangeal joint. The thumb metacarpophalangeal joint was also able to be fully actively extended by the EPB. Previous anatomical studies have demonstrated that the insertional anatomy of the EPB tendon is highly variable and sometimes inserts onto the extensor hood and distal phalanx, which is likely the mechanism by which our patient was able to fully extend the thumb interphalangeal joint. Despite the potential for the EPB to extend the IP joint of the thumb, virtually all previously reported cases of extensor pollicis longus(EPL) tendon rupture had deficits of thumb IP extension requiring tendon transfer. This case highlights the potential ability of the EPB tendon to completely substitute for the function of the EPL tendon in providing thumb IP joint extension.

Multiple tendons of the additional belly of flexor pollicis longus in the carpal tunnel: Embryological perspective and their clinical significance

Although the flexor pollicis longus is known to show the additional head of the origin, the occurrence of its additional tendons in the carpal tunnel are seldom reported. The presence of such additional tendons in the carpal tunnel cannot be overlooked during the radiological and surgical procedures in this region. Herein, we report a rare case of additional muscle belly of flexor pollicis longus. The additional muscle belly after a short course divided into three tendons. All three tendons entered the carpal tunnel along with flexor pollicis longus, passing deep to the flexor retinaculum. Within the carpal tunnel, two of these tendons fused and terminated by merging with the undersurface of the flexor retinaculum. The third tendon terminated by joining the flexor digitorum superficialis tendon for the index finger, in the palm. An additional slip of the first lumbrical muscle took origin from the third tendon of the additional muscle belly of flexor pollicis longus. Further, the embryological basis and clinical significance of current case is discussed.

Brachioradialis tendon transfer and palmaris longus tendon graft for thumb avulsion:A case report and review of literature

BACKGROUND Thumb replantation following complete traumatic avulsion requires complex techniques to restore function,especially in cases of avulsion at the level of the metacarpophalangeal joint(MCP I)and avulsion of the flexor pollicis longus(FPL)at the musculotendinous junction.Possible treatments include direct tendon suture or tendon transfer,most commonly from the ring finger.To optimize function and avoid donor finger complications,we performed thumb replantation with flexion restoration using brachioradialis(BR)tendon transfer with palmaris longus(PL)tendon graft.CASE SUMMARY A 20-year-old left-handed male was admitted for a complete traumatic left thumb amputation following an accident while sliding from the top of a handrail.The patient presented with skin and bone avulsion at the MCP I,avulsion of the FPL tendon at the musculotendinous junction(zone 5),avulsion of the extensor pollicis longus tendon(zone T3),and avulsion of the thumb’s collateral arteries and nerves.The patient was treated with two stage thumb repair.The first intervention consisted of thumb replantation with MCP I arthrodesis,resection of avulsed FPL tendon and implantation of a silicone tendon prosthesis.The second intervention consisted of PL tendon graft and BR tendon transfer.Follow-up at 10 months showed good outcomes with active interphalangeal flexion of 70°,grip strength of 45 kg,key pinch strength of 15 kg and two-point discrimination threshold of 4 mm.CONCLUSION Flexion restoration after complete thumb amputation with FPL avulsion at the musculotendinous junction can be achieved using BR tendon transfer with PL tendon graft.