- Email: [email protected]
Surgical exposure of the flexor pollicis longus tendon
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Brunet
S U R G I C A L E X P O S U R E OF THE F L E X O R POLLICIS L O N G U S T E N D O N
J U L I A N M. BRUNER, Des Moines, Iowa SUMMARY Primary and secondary tendon repair in the metacarpal (thenar) zone of the thumb has been successfully performed. The zone can be explored by a proximal extension of the volar zig-zag incision used o+er the phalanges of the thumb. The surgical anatomy of this area is fully described and illustrated and the results of two successful cases given. INTRODUCTION In penetrating wounds of the thenar eminence, the flexor pollicis longus tendon is frequently severed with loss of voluntary flexion at the interphalangeal joint of the thumb. In such cases the experienced hand surgeon gains access to the cut tendon directly through the traumatic wound. Acute passive flexion of the wrist usually serves to bring the proximal stump of the tendon into view within the wound, where it may be sutured to the distal stump without difficulty. An auxiliary incision at the wrist level to retrieve the proximal stump is usually not necessary. The motor and sensory branches of the median nerve are then identified, and if severed, they are sutured. Finally the thenar muscles are repaired and the skin wound is closed. METHOD Results of primary tendon repair in the thenar zone (between the distal end of the carpal canal and the digital theca of the thumb at the metacarpophalangeal level) are, in my experience, usually successful. In this area, the flexor pollicis longus tendon is not restrained by tight retinacula; if post-operative adhesions occur after such primary tendon suture, they are gradually broken down by the continued to-and-fro movements of the flexor pollicis longus tendon, as function is re-established. The above suggests that the metacarpal (thenar) zone of the thumb, usually considered inaccessible for surgery of the flexor pollicis longus tendon, is in fact as favourable an area for primary tenorrhapy or for tendon graft as is the corresponding (metacarpal) area in the proximal half of the palm for repair of the flexor tendons of the fingers. Thus the thenar zone is the "last frontier" in the surgical exposure of the flexor tendons of the hand. In all other areas on the palmar aspect of the digits and hand, the flexor tendons have been rendered easily accessible through the volar zig-zag incision on the digits and in the palm, and at the wrist level by a carpal tunnel incision which remains strictly ulnar to the median nerve (Bruner, 1966, 1967).. If the various zones are graded as to whether they are favourable for primary flexor tenorrhaphy, they would rank as follows: (Most favourable.) (1) Volar surface of the wrist proximal to the carpal canal. (2) Metacarpal area in proximal half of the palm; to this zone, I think should be added the metacarpal (thenar) segment of the thumb. (3) Distal half of all digits. (4) "No man's land" and carpal tunnel zone. (Least favourable.) (Note: If the transverse carpal ligament is completely divided and is left open, the carpal tunnel zone is not unfavourable.) The Harid---Vol. 7
No. 3
1975
241
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Bruner
Fig. 1. Surgical exposure of the flexor pollicis longus tendon. Returning to the thumb, the flexor pollicis tendon may be exposed distally when indicated, by the volar zig-zag incision which skirts the volar edge of the digital nerve, and cuts no nerve fibres, even in the distal segment (pulp). At the level of the metacarpophalangeal joint, this incision may be extended proximally toward the centre of the palm on the thenar surface. The tendons of the opponens pollicis and the flexor pollicis brevis (each of which contains a sesamoid bone) are identified at their insertions into the base of the proximal phalanx, and are retracted one to each side. The volar digital nerves and arteries are visualised (using a two-power loupe), and the thenar fascia is incised. This exposes the adductor muscle of the thumb which lies just ulnar to the channel for the tendon. In old injuries, if proximal stump of the flexor pollicis longus tendon has retracted to the wrist level, and is thus atrophic and shortened, a wrist incision is necessary. But if the tendon is intact a n & in continuity, although firmly immobilised by adhesions distal to the metacarpophalangeal joint level, the above manoeuvre may be indicated for tendon graft. Thus the graft may be shorter, and only one incision is required. If other digital flexor tendons are involved and must be inspected at the wrist, the carpal tunnel incision should be used and the transverse carpal ligament completely divided as in decompression of the median nerve for carpal tunnel syndrome. This incision is often depicted in text books with a wide sweep round the base of the thenar eminence, thus transecting at right angles the superficial volar branch of the radial artery as well as the palmar (sensory) branch of the 242
The Hand--Vol. 7
No. 3
1975
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Bruner
median nerve. If this tiny sensory nerve is cut, the resulting painful neuroma and the area of paraesthesia in the palm are very disabling and may be incurable. Correct delineation of the carpal tunnel incision was described by Sir James Learmonth (who did the first published decompression of the median nerve in 1930) and is as follows: It begins 3-5 mm. ulnar to the thenar skin crease in the proximal palm, and is continued proximally with small zig-zags at the wrist level. The correct incision, he insisted, remains just ulnar to the palmaris longus tendon (when present) and is therefore ulnar to the median nerve at all points (Learmonth, 1933, 1966). Thus the palmar branch of the median nerve and the superficial volar branch of the radial artery are not jeopardised. CASE HISTORIES
CASE I - - M r . P. H., age twenty-three, fell to the ground on July 24th, 1973, his hand striking broken glass which penetrated the thenar area, with division of the flexor pollicis longus tendon, one digital nerve, and portions of the thenar muscles (Fig. 2). On the following day, the cut tendon and digital nerve (to radial half of thumb) were repaired. Recovery was normal. At present fourteen months later he has regained excellent sensation in the thumb and full range of voluntary flexion at the interphalangeal joint. Full recovery in such cases is not uncommon.
CASE I I - - M r . D . H . , age twenty-eight, sustained a deep glass cut on the volar surface of thumb just distal to metacarpophalangeal joint.. Two attempts at repair had been done elsewhere (Fig. 3): a primary repair of the flexor pollicis longus tendon on day of injury; two months later a millipore membrane had been inserted around the stuck tendon in the proximal thumb segment. In August, 1973, when first seen by me three months after injury, voluntary flexion of the interphalangeal joint was absent and a 30 ° flexion contracture was present in this joint. On January 15th, 1974, a palmaris longus tendon graft was done through a volar zig-zag incision on the volar surface of thumb,
Fig. 2. Case 1. Flexor tendon and one digital nerve repaired by suture one day after injury. The H a n d - - V o l . 7
No. 3
1975
243
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Bruner
Fig. 3. Case 2. Late repair of flexor pollicis longus by tendon graft. augmented proximally by an incision over the thenar area. General recovery of flexor pollicis longus tendon function took place, and today the range of voluntary motion at the interphalangeal joint is 150 °/90 °. DISCUSSION
In the fingers, proximal exposure for flexor tendon grafting is usually made in the metacarpal zone, not at the wrist. This is dictated by the lumbrical muscles, whose origin from the profundus tendon requires that the proximal end of the graft be fixed just distal to this point. In the thumb, the absence of a lumbrical muscle is a favourable factor in tendon grafting, which is thus freed from "lumbrical plus" and other complications. Theoretically then in the thumb, the proximal end of the tendon graft may be fixed to the flexor pollicis longus tendon either at the wrist or in the thenar zone. In most cases exposure is best obtained at the wrist level just radial to the flexor carpi radialis tendon, although this entails passing the graft through the carpal tunnel and round the bend at the base of the thumb. But in selected cases in which the flexor pollicis longus tendon is free of adhesions proximal to the metacarpophalangeal joint and is helping to flex that joint, exposure may be entirely distal. CONCLUSION In the thenar zone the surgeon may gain access to fire flexor pollicis longus tendon by making his incision "along the ridge pole of a thatched r o o f " under which the tendon lies, xHe must be familiar with the anatomy of the area, with the position of the digital nerves and arteries on the thenar fascia, and with the small intrinsic (thenar) muscles whose tendons of insertion contain the two sesamoid bones. He must make his incision in such a way that a sensitive scar or flexion contracture will not follow. If he is competent in these two respects, access to the flexor pollicis longus tendon in the thenar zone will, in selected cases, save time and provide excellent exposure for repair and functional restoration of this important tendon. 244
The H a n d - - V o l . 7
No. 3
1975
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Brunet REFERENCES
LEARMONTH, J. R. (1933) The Principle Of Decompression In The Treatment Of Certain Diseases Of Peripheral Nerves. Surgical Clinics of North America, 13: 905-913. LEARMONTH, Sir James (1966) Personal communication. BRUNER, L M. (1967) The Zig-Zag Volar-Digital Incision for Flexor-Tendon Surgery. Plastic and Reconstructive Surgery, 40: 571~74. BRUNER, J. M. (1973) Surgical Exposure Of Flexor Tendons In The Hand. Annals of the Royal College of Surgeons of England, 53: 84-94.
The H a n d - - V o l . 7
No. 3
1975
245
S U R G I C A L E X P O S U R E OF THE F L E X O R POLLICIS L O N G U S T E N D O N
J U L I A N M. BRUNER, Des Moines, Iowa SUMMARY Primary and secondary tendon repair in the metacarpal (thenar) zone of the thumb has been successfully performed. The zone can be explored by a proximal extension of the volar zig-zag incision used o+er the phalanges of the thumb. The surgical anatomy of this area is fully described and illustrated and the results of two successful cases given. INTRODUCTION In penetrating wounds of the thenar eminence, the flexor pollicis longus tendon is frequently severed with loss of voluntary flexion at the interphalangeal joint of the thumb. In such cases the experienced hand surgeon gains access to the cut tendon directly through the traumatic wound. Acute passive flexion of the wrist usually serves to bring the proximal stump of the tendon into view within the wound, where it may be sutured to the distal stump without difficulty. An auxiliary incision at the wrist level to retrieve the proximal stump is usually not necessary. The motor and sensory branches of the median nerve are then identified, and if severed, they are sutured. Finally the thenar muscles are repaired and the skin wound is closed. METHOD Results of primary tendon repair in the thenar zone (between the distal end of the carpal canal and the digital theca of the thumb at the metacarpophalangeal level) are, in my experience, usually successful. In this area, the flexor pollicis longus tendon is not restrained by tight retinacula; if post-operative adhesions occur after such primary tendon suture, they are gradually broken down by the continued to-and-fro movements of the flexor pollicis longus tendon, as function is re-established. The above suggests that the metacarpal (thenar) zone of the thumb, usually considered inaccessible for surgery of the flexor pollicis longus tendon, is in fact as favourable an area for primary tenorrhapy or for tendon graft as is the corresponding (metacarpal) area in the proximal half of the palm for repair of the flexor tendons of the fingers. Thus the thenar zone is the "last frontier" in the surgical exposure of the flexor tendons of the hand. In all other areas on the palmar aspect of the digits and hand, the flexor tendons have been rendered easily accessible through the volar zig-zag incision on the digits and in the palm, and at the wrist level by a carpal tunnel incision which remains strictly ulnar to the median nerve (Bruner, 1966, 1967).. If the various zones are graded as to whether they are favourable for primary flexor tenorrhaphy, they would rank as follows: (Most favourable.) (1) Volar surface of the wrist proximal to the carpal canal. (2) Metacarpal area in proximal half of the palm; to this zone, I think should be added the metacarpal (thenar) segment of the thumb. (3) Distal half of all digits. (4) "No man's land" and carpal tunnel zone. (Least favourable.) (Note: If the transverse carpal ligament is completely divided and is left open, the carpal tunnel zone is not unfavourable.) The Harid---Vol. 7
No. 3
1975
241
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Bruner
Fig. 1. Surgical exposure of the flexor pollicis longus tendon. Returning to the thumb, the flexor pollicis tendon may be exposed distally when indicated, by the volar zig-zag incision which skirts the volar edge of the digital nerve, and cuts no nerve fibres, even in the distal segment (pulp). At the level of the metacarpophalangeal joint, this incision may be extended proximally toward the centre of the palm on the thenar surface. The tendons of the opponens pollicis and the flexor pollicis brevis (each of which contains a sesamoid bone) are identified at their insertions into the base of the proximal phalanx, and are retracted one to each side. The volar digital nerves and arteries are visualised (using a two-power loupe), and the thenar fascia is incised. This exposes the adductor muscle of the thumb which lies just ulnar to the channel for the tendon. In old injuries, if proximal stump of the flexor pollicis longus tendon has retracted to the wrist level, and is thus atrophic and shortened, a wrist incision is necessary. But if the tendon is intact a n & in continuity, although firmly immobilised by adhesions distal to the metacarpophalangeal joint level, the above manoeuvre may be indicated for tendon graft. Thus the graft may be shorter, and only one incision is required. If other digital flexor tendons are involved and must be inspected at the wrist, the carpal tunnel incision should be used and the transverse carpal ligament completely divided as in decompression of the median nerve for carpal tunnel syndrome. This incision is often depicted in text books with a wide sweep round the base of the thenar eminence, thus transecting at right angles the superficial volar branch of the radial artery as well as the palmar (sensory) branch of the 242
The Hand--Vol. 7
No. 3
1975
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Bruner
median nerve. If this tiny sensory nerve is cut, the resulting painful neuroma and the area of paraesthesia in the palm are very disabling and may be incurable. Correct delineation of the carpal tunnel incision was described by Sir James Learmonth (who did the first published decompression of the median nerve in 1930) and is as follows: It begins 3-5 mm. ulnar to the thenar skin crease in the proximal palm, and is continued proximally with small zig-zags at the wrist level. The correct incision, he insisted, remains just ulnar to the palmaris longus tendon (when present) and is therefore ulnar to the median nerve at all points (Learmonth, 1933, 1966). Thus the palmar branch of the median nerve and the superficial volar branch of the radial artery are not jeopardised. CASE HISTORIES
CASE I - - M r . P. H., age twenty-three, fell to the ground on July 24th, 1973, his hand striking broken glass which penetrated the thenar area, with division of the flexor pollicis longus tendon, one digital nerve, and portions of the thenar muscles (Fig. 2). On the following day, the cut tendon and digital nerve (to radial half of thumb) were repaired. Recovery was normal. At present fourteen months later he has regained excellent sensation in the thumb and full range of voluntary flexion at the interphalangeal joint. Full recovery in such cases is not uncommon.
CASE I I - - M r . D . H . , age twenty-eight, sustained a deep glass cut on the volar surface of thumb just distal to metacarpophalangeal joint.. Two attempts at repair had been done elsewhere (Fig. 3): a primary repair of the flexor pollicis longus tendon on day of injury; two months later a millipore membrane had been inserted around the stuck tendon in the proximal thumb segment. In August, 1973, when first seen by me three months after injury, voluntary flexion of the interphalangeal joint was absent and a 30 ° flexion contracture was present in this joint. On January 15th, 1974, a palmaris longus tendon graft was done through a volar zig-zag incision on the volar surface of thumb,
Fig. 2. Case 1. Flexor tendon and one digital nerve repaired by suture one day after injury. The H a n d - - V o l . 7
No. 3
1975
243
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Bruner
Fig. 3. Case 2. Late repair of flexor pollicis longus by tendon graft. augmented proximally by an incision over the thenar area. General recovery of flexor pollicis longus tendon function took place, and today the range of voluntary motion at the interphalangeal joint is 150 °/90 °. DISCUSSION
In the fingers, proximal exposure for flexor tendon grafting is usually made in the metacarpal zone, not at the wrist. This is dictated by the lumbrical muscles, whose origin from the profundus tendon requires that the proximal end of the graft be fixed just distal to this point. In the thumb, the absence of a lumbrical muscle is a favourable factor in tendon grafting, which is thus freed from "lumbrical plus" and other complications. Theoretically then in the thumb, the proximal end of the tendon graft may be fixed to the flexor pollicis longus tendon either at the wrist or in the thenar zone. In most cases exposure is best obtained at the wrist level just radial to the flexor carpi radialis tendon, although this entails passing the graft through the carpal tunnel and round the bend at the base of the thumb. But in selected cases in which the flexor pollicis longus tendon is free of adhesions proximal to the metacarpophalangeal joint and is helping to flex that joint, exposure may be entirely distal. CONCLUSION In the thenar zone the surgeon may gain access to fire flexor pollicis longus tendon by making his incision "along the ridge pole of a thatched r o o f " under which the tendon lies, xHe must be familiar with the anatomy of the area, with the position of the digital nerves and arteries on the thenar fascia, and with the small intrinsic (thenar) muscles whose tendons of insertion contain the two sesamoid bones. He must make his incision in such a way that a sensitive scar or flexion contracture will not follow. If he is competent in these two respects, access to the flexor pollicis longus tendon in the thenar zone will, in selected cases, save time and provide excellent exposure for repair and functional restoration of this important tendon. 244
The H a n d - - V o l . 7
No. 3
1975
Surgical Exposure of the Flexor Pollicis Longus Tendon--Julian M. Brunet REFERENCES
LEARMONTH, J. R. (1933) The Principle Of Decompression In The Treatment Of Certain Diseases Of Peripheral Nerves. Surgical Clinics of North America, 13: 905-913. LEARMONTH, Sir James (1966) Personal communication. BRUNER, L M. (1967) The Zig-Zag Volar-Digital Incision for Flexor-Tendon Surgery. Plastic and Reconstructive Surgery, 40: 571~74. BRUNER, J. M. (1973) Surgical Exposure Of Flexor Tendons In The Hand. Annals of the Royal College of Surgeons of England, 53: 84-94.
The H a n d - - V o l . 7
No. 3
1975
245