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A troublesome flexor tendon anomaly
A TroublesomeFlexor Tendon Anomaly D. M. Evans A TROUBLESOME
FLEXOR TENDON ANOMALY
D. M. EVANS SUMMARY A n anatomical variation is described in which a connection between f l e x o r digitorum superficialis and profundus o f the ring finger led to difficulty in withdrawing the superficial tendon f o r transfer.
INTRODUCTION The use of flexor digitorum superficialis as a tendon transfer is well established. In order to withdraw the tendon proximally the split distal end has to be divided near the base o f th~ fingers, and the decussation of Camper split so that it no longer encircles the profundus tendon. If this is not done it is possible to draw the tendon proximally only as far as the lumbrical origin at which point further traction causes flexion of the finger. A case is reported where an anomalous connection between superficial and deep tendons produced the same effect. A CASE REPORT
A twenty:seven year old male presented with a closed rupture o f extensor pollicis longus, sixyears after extensive reconstructive surgery following an avulsion injury of the dorsum of the left hand; this had included an abdominal flap f o l l o w e d by trapeziectomy and web space reconstruction, and tendon grafts to the extensors of the thumb and index finger. He had regained good function, with slight limitation o f thumb span and opposition, but the subsequent tendon rupture had compromised the use of the thumb. Flexor digitorum superficialis was chosen as a transfer to extensor pollicis longus in order to improve opposition as well as restore interphalangeal extension. The superficial tendon of the ring finger was divided at the base o f the finger and the decussation split. Proximal traction on the tendon, through a forearm incision produced tight flexion of both interphalangeal joints o~ the ring finger, and when the tendon was re-examined distally it was confirmed that the decussation was completely divided. The tendon still could not be withdrawn, and eventually a narrow tendon was found arising from the superficialis tendon in the distal forearm and joining the profundus tendon, presumably somewhere in the forearm. When this had been divided the superficialis could be withdrawn and rerouted to the thumb (Fig. 1). Traction on the fine anomalous tendon still produced flexion of the whole finger (Fig. 2). Flexor digitorum profundus was examined and found to function normally, independently of the anomalous tendon (Fig. 3), which was then attached to the main profundus tendon to prevent it from adhering elsewhere. DISCUSSION I have been unable to find a case report of a similar anomaly. Wood Jones (1949) points out that in many animals there is considerable blending of the deep and superficial flexor systems, and mentions that in man they may share a few fibres o f c o m m o n origin. Murakami and Edashige (1980) report an anomalous connection between flexor pollicis longus and flexor digitorum profundus o f the index finger. D. M. Evans, F.R.C.S., Department of Plastic Surgery, Wexham Park Hospital, Slough SL2 4HL. 9 1982 British Societyfor Surgery of the Hand 0072-968X-82-00110051 $02.00 The Hand-- Volume 14
No. 1
1982
51
A Troublesome Flexor Tendon Anomaly D. M. Evans
Fig. 1. The anomalous tendon connecting superficial and deep flexors is held loosely in a haemostat. Flexor digitorum superficialis has been rerouted to the dorsum of the thumb for attachment to extensor pollicis longus. Fig. 2. Traction on the anomalous tendon flexes the ring finger at all its joints. Fig. 3. The common profundus tendon mass to the ulnar three fingers is shown to function normally, independently of the anomalous tendon. F u r n a s (1965) d e s c r i b e d a n e x t r a muscle n a m e d f l e x o r d i g i t o r u m m i n o r , which inserted into the f o u r superficialis t e n d o n s , a n d also sent a slip to flexor d i g i t o r u m p r o f u n d u s o f the little finger, b u t n o t the ring finger. H e also twice o b s e r v e d a small a c c e s s o r y t e n d o n arising f r o m the i n t e r m e d i a t e t e n d o n o f the d e e p h e a d o f flexor d i g i t o r u m superficialis a n d j o i n i n g the p r o f u n d u s t e n d o n o f the little finger. T h e d i f f e r e n c e is i m p o r t a n t b e c a u s e the superficial t e n d o n o f the little finger arises f r o m t h e d e e p h e a d w h e r e a s t h a t o f t h e ring finger arises f r o m t h e superficial h e a d . A s W o o d J o n e s p o i n t e d o u t (1949) h u m a n muscles are subject to n u m e r o u s v a r i a t i o n s . T h e m a j o r i t y a r e o f n o m o r e t h a n a c a d e m i c interest; this one is r e p o r t e d b e c a u s e o f t h e u n e x p e c t e d d i f f i c u l t y it p r o d u c e d in a n otherwise r o u t i n e o p e r a t i o n , REFERENCES
FURNAS, D. W. (1965) Muscle-Tendon Variations in the Flexor Compartment of the Wrist. Plastic and Reconstructive Surgery, 36: 320-324. MURAKAMI, Y. and EDASHIGE, K. (1980) Anomalous Flexor Pollicis Longus Muscle. The Hand, 12: 82-84. WOOD JONES, F. Principles of Anatomy as seen in the Hand; 2rid Edition. London. Bailli~re, Tindall and Cox (1949) p.169.
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The H a n d - - Volume 14
No. 1
1982
FLEXOR TENDON ANOMALY
D. M. EVANS SUMMARY A n anatomical variation is described in which a connection between f l e x o r digitorum superficialis and profundus o f the ring finger led to difficulty in withdrawing the superficial tendon f o r transfer.
INTRODUCTION The use of flexor digitorum superficialis as a tendon transfer is well established. In order to withdraw the tendon proximally the split distal end has to be divided near the base o f th~ fingers, and the decussation of Camper split so that it no longer encircles the profundus tendon. If this is not done it is possible to draw the tendon proximally only as far as the lumbrical origin at which point further traction causes flexion of the finger. A case is reported where an anomalous connection between superficial and deep tendons produced the same effect. A CASE REPORT
A twenty:seven year old male presented with a closed rupture o f extensor pollicis longus, sixyears after extensive reconstructive surgery following an avulsion injury of the dorsum of the left hand; this had included an abdominal flap f o l l o w e d by trapeziectomy and web space reconstruction, and tendon grafts to the extensors of the thumb and index finger. He had regained good function, with slight limitation o f thumb span and opposition, but the subsequent tendon rupture had compromised the use of the thumb. Flexor digitorum superficialis was chosen as a transfer to extensor pollicis longus in order to improve opposition as well as restore interphalangeal extension. The superficial tendon of the ring finger was divided at the base o f the finger and the decussation split. Proximal traction on the tendon, through a forearm incision produced tight flexion of both interphalangeal joints o~ the ring finger, and when the tendon was re-examined distally it was confirmed that the decussation was completely divided. The tendon still could not be withdrawn, and eventually a narrow tendon was found arising from the superficialis tendon in the distal forearm and joining the profundus tendon, presumably somewhere in the forearm. When this had been divided the superficialis could be withdrawn and rerouted to the thumb (Fig. 1). Traction on the fine anomalous tendon still produced flexion of the whole finger (Fig. 2). Flexor digitorum profundus was examined and found to function normally, independently of the anomalous tendon (Fig. 3), which was then attached to the main profundus tendon to prevent it from adhering elsewhere. DISCUSSION I have been unable to find a case report of a similar anomaly. Wood Jones (1949) points out that in many animals there is considerable blending of the deep and superficial flexor systems, and mentions that in man they may share a few fibres o f c o m m o n origin. Murakami and Edashige (1980) report an anomalous connection between flexor pollicis longus and flexor digitorum profundus o f the index finger. D. M. Evans, F.R.C.S., Department of Plastic Surgery, Wexham Park Hospital, Slough SL2 4HL. 9 1982 British Societyfor Surgery of the Hand 0072-968X-82-00110051 $02.00 The Hand-- Volume 14
No. 1
1982
51
A Troublesome Flexor Tendon Anomaly D. M. Evans
Fig. 1. The anomalous tendon connecting superficial and deep flexors is held loosely in a haemostat. Flexor digitorum superficialis has been rerouted to the dorsum of the thumb for attachment to extensor pollicis longus. Fig. 2. Traction on the anomalous tendon flexes the ring finger at all its joints. Fig. 3. The common profundus tendon mass to the ulnar three fingers is shown to function normally, independently of the anomalous tendon. F u r n a s (1965) d e s c r i b e d a n e x t r a muscle n a m e d f l e x o r d i g i t o r u m m i n o r , which inserted into the f o u r superficialis t e n d o n s , a n d also sent a slip to flexor d i g i t o r u m p r o f u n d u s o f the little finger, b u t n o t the ring finger. H e also twice o b s e r v e d a small a c c e s s o r y t e n d o n arising f r o m the i n t e r m e d i a t e t e n d o n o f the d e e p h e a d o f flexor d i g i t o r u m superficialis a n d j o i n i n g the p r o f u n d u s t e n d o n o f the little finger. T h e d i f f e r e n c e is i m p o r t a n t b e c a u s e the superficial t e n d o n o f the little finger arises f r o m t h e d e e p h e a d w h e r e a s t h a t o f t h e ring finger arises f r o m t h e superficial h e a d . A s W o o d J o n e s p o i n t e d o u t (1949) h u m a n muscles are subject to n u m e r o u s v a r i a t i o n s . T h e m a j o r i t y a r e o f n o m o r e t h a n a c a d e m i c interest; this one is r e p o r t e d b e c a u s e o f t h e u n e x p e c t e d d i f f i c u l t y it p r o d u c e d in a n otherwise r o u t i n e o p e r a t i o n , REFERENCES
FURNAS, D. W. (1965) Muscle-Tendon Variations in the Flexor Compartment of the Wrist. Plastic and Reconstructive Surgery, 36: 320-324. MURAKAMI, Y. and EDASHIGE, K. (1980) Anomalous Flexor Pollicis Longus Muscle. The Hand, 12: 82-84. WOOD JONES, F. Principles of Anatomy as seen in the Hand; 2rid Edition. London. Bailli~re, Tindall and Cox (1949) p.169.
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The H a n d - - Volume 14
No. 1
1982