Congenital Bilateral Anomalous Band between Flexor and Extensor Pollicis Longus Tendons-R. Salama and S. L. Weissman
CONGENITAL BILATERAL ANOMALOUS BAND BETWEEN F L E X O R A N D E X T E N S O R POLLICIS L O N G U S T E N D O N S Report of a case R. S A L A M A and S. L. W E I S S M A N , Tel-Aviv, Israel
A girl aged three years was admitted to hospital in January, 1973 because of absence of active flexion of the distal phalanx of both thumbs since birth. Active extension was possible but very limite& Passive flexion and extension were slightly limited. General examination did not reveal any other abnormality, The tentative diagnosis was congenital bilateral tendovaginitis stenosans. Exploration was p e r f o r m e d under general anaesthesia and a tourniquet, by means of a transverse incision overlying the metacarpophalangeal joint of the thumb. The flexor pollicis tendon was found to be kinked and displaced laterally towards the lateral surface of the metacarpophalangeal joint (Fig. 1). It was fixed there by a narrow tendinous band which extended distally obliquely f r o m its lateral border to t h e l a t e r a l border of the extensor pollicis longus. Traction on the flexor tendon distal to the tendinous band resulted in flexion of the distal phalanx which however did not move when traction was applied proximal to the tendinous band. Traction on the extensor tendon both proximal and distal to the band resulted in extension of the distal phalanx. Following excision of the tendinous band both tendons returned to their normal anatomical positions and traction on the flexor tendon proximally resulted in normal flexion of the distal phalanx. A soft tissue pulley was reconstructed for the flexor tendon at the level of the metacarpophalangeal joint and the wound was closed. The t h u m b was immobilised in a soft bandage in opposition for ten days following which the child was left free to play and move her thumbs. Recovery of function was very gradual but by December, 1973 both flexion and extension had almost returned to normal (Fig. 2). The operative findings and procedures were identical in both thumbs.
Fig. 1. At operation the anomalous fibrous band can be seen joining the flexor to the extensor pollicis longus in the right hand. F.P.L.--Flexor pollicis longus. E.P.L.--Extensor pollicis longus. Fig, 2. The left hand eleven months after operation. Flexion of the interphalangeal joint of the thumb is almost normal. The Hand--Vol. 7
No. 1
1975
25
Congenital Bilateral Anomalous Band between Flexor and Extensor Pollicis Longus Tendons-R. Salama and S. L. Weissman DISCUSSION
The origin of a congenital anomalous fibrous band joining the flexor to the extensor pollicis longus tendons is very difficult to explain since it does not conform to any developmental pattern. It does not correspond to any known arrest or aberration in development at any stage of embryonic life and does not conform to any phylogenetic atavism. Functionally, the absence of active flexion resulted from a tenodesing effect of the fibrous band which transmitted the pull of the flexor pollicis longus to the extensor tendon. SUMMARY
A bilateral congenital abnormality of the long tendons of the thumb consisting of a tendinous band joining flexor to extensor pollicis longus at the level of the metacarpophalangeal joint is described in a child aged three years. This abnormality appears not to have been reported before.
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The Hand--Vol. 7
No. 1
1975
CONGENITAL BILATERAL ANOMALOUS BAND BETWEEN F L E X O R A N D E X T E N S O R POLLICIS L O N G U S T E N D O N S Report of a case R. S A L A M A and S. L. W E I S S M A N , Tel-Aviv, Israel
A girl aged three years was admitted to hospital in January, 1973 because of absence of active flexion of the distal phalanx of both thumbs since birth. Active extension was possible but very limite& Passive flexion and extension were slightly limited. General examination did not reveal any other abnormality, The tentative diagnosis was congenital bilateral tendovaginitis stenosans. Exploration was p e r f o r m e d under general anaesthesia and a tourniquet, by means of a transverse incision overlying the metacarpophalangeal joint of the thumb. The flexor pollicis tendon was found to be kinked and displaced laterally towards the lateral surface of the metacarpophalangeal joint (Fig. 1). It was fixed there by a narrow tendinous band which extended distally obliquely f r o m its lateral border to t h e l a t e r a l border of the extensor pollicis longus. Traction on the flexor tendon distal to the tendinous band resulted in flexion of the distal phalanx which however did not move when traction was applied proximal to the tendinous band. Traction on the extensor tendon both proximal and distal to the band resulted in extension of the distal phalanx. Following excision of the tendinous band both tendons returned to their normal anatomical positions and traction on the flexor tendon proximally resulted in normal flexion of the distal phalanx. A soft tissue pulley was reconstructed for the flexor tendon at the level of the metacarpophalangeal joint and the wound was closed. The t h u m b was immobilised in a soft bandage in opposition for ten days following which the child was left free to play and move her thumbs. Recovery of function was very gradual but by December, 1973 both flexion and extension had almost returned to normal (Fig. 2). The operative findings and procedures were identical in both thumbs.
Fig. 1. At operation the anomalous fibrous band can be seen joining the flexor to the extensor pollicis longus in the right hand. F.P.L.--Flexor pollicis longus. E.P.L.--Extensor pollicis longus. Fig, 2. The left hand eleven months after operation. Flexion of the interphalangeal joint of the thumb is almost normal. The Hand--Vol. 7
No. 1
1975
25
Congenital Bilateral Anomalous Band between Flexor and Extensor Pollicis Longus Tendons-R. Salama and S. L. Weissman DISCUSSION
The origin of a congenital anomalous fibrous band joining the flexor to the extensor pollicis longus tendons is very difficult to explain since it does not conform to any developmental pattern. It does not correspond to any known arrest or aberration in development at any stage of embryonic life and does not conform to any phylogenetic atavism. Functionally, the absence of active flexion resulted from a tenodesing effect of the fibrous band which transmitted the pull of the flexor pollicis longus to the extensor tendon. SUMMARY
A bilateral congenital abnormality of the long tendons of the thumb consisting of a tendinous band joining flexor to extensor pollicis longus at the level of the metacarpophalangeal joint is described in a child aged three years. This abnormality appears not to have been reported before.
26
The Hand--Vol. 7
No. 1
1975
