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The abductor digiti minimi muscle flap
The Abductor Digiti Minimi Muscle Flap --Timothy M. Milward, Wayne G. Stott, Harold E. Kleinert
THE ABDUCTOR
DIGITI MINIMI
MUSCLE
FLAP
T I M O T H Y M. M I L W A R D , Leicester, W A Y N E G. STOTT, Melbourne, and H A R O L D E. K L E I N E R T , Louisville SUMMARY
The problems of extensive scarring involving the median and ulnar nerves at the wrist are discussed. Possible methods of separating the dermal cicatrix from the nerves are skin flaps or muscle flaps. A case is presented in which an abductor digiti minimi muscle flap was used. The reasons for this choice are discussed and the technique described. INTRODUCTION
Though muscle flaps have been used increasingly for the solution of lower limb skin cover problems since first described by Ger (1966) over a decade ago, their use in the upper limb has not been described and we would like to present one such flap that we' have found useful in the hand. There is the occasional patient who, following repeated carpal tunnel surgery, develops a vicious cycle of progressive dermal scarring, loss of subcutaneous fat, increasing constrictive fibrosis around median and ulnar nerves with symptoms tempting the surgeon to attempt further neurolysis. If surgery is to be undertaken with any hope of success, some new tissue must be introduced between scarred skin and nerves. Possibilities are the subcutaneous fat of a skin flap or a muscle flap as used in this case. The practicability of the muscle flap is now well established (Ger 1966, Pers 1973, Vasconez 1974) mainly from its use in lower leg defects where the flap is surfaced with a skin graft. Less attention has been paid to the technique in the hand because a distant skin flap is usually available. When for various reasons a skin flap is not advisable, a muscle flap should be considered. THE ABDUCTOR DIGITI MINIMI MUSCLE FLAP
Abductor digiti minimi is a muscle whose transfer potential was recognised early on. Huber (1921) and Nicolaysen (1922) used this ulnar innervated muscle for opponens plasty in isolated median nerve palsy. Littler and Cooley (1963) reported a further five cases using this technique successfully. It is particularly suitable as a donor muscle having a compact single neurovascular bundle of reliably constant position Huber (1921), Sunderland and Hughes (1946), Brash (1955) and leaving little functional defect as flexor digiti minimi substitutes for it. To obtain maximum mobility it needs to be completely freed from both origin and insertion leaving the neurovascular bundle as its sole attachment. This is in contrast to many long muscle tendon transfers and requires meticulous dissection to avoid compromising the blood supply. Littler and Cooley rightly stress that the method is technically difficult. Timothy M. Milward, F.R.C.S., The Leicester Royal Infirmary, Leicester, LEI 5WW. 82
The Hand--Vol. 9
No. 1
1977
The Abductor Digiti Minimi Muscle Flap --Timothy M. Milward, Wayne G. Stott, Harold E, Kleinert
CASE REPORT
In 1970 a sixty-nine year old woman sustained a Colles' fracture to the right wrist. Following closed reduction and plaster casting she developed acute carpal tunnel compression. This was treated surgically at three weeks with decompression, ulnar head excision and both internal and external neurolysis of ulnar and median nerves. Subsequent hand swelling and scalding wrist pain were thought to be Sympathetic Dystrophy and were treated by a stellate sympathectomy in early 1971 without relief. In late 1971 due to the persistent symptoms
Fig, 1. Abductor Digiti Minimi muscle isolated on neurovascular pedicle.
Fig. 2.
Muscle tunnelled through into palm.
The Hand--Vol. 9
No. 1
1977
83
The Abductor Digiti Minimi Muscle Flap --Timothy M. Milward, Wayne G. Stott, Harold E. Kleinert
Fig. 3. Muscle fanned out over median and ulnar nerves. the area was re-explored with no improvement. In 1975 the patient first came under our care. At that time her complaint was of an icy-cold sensation in the hand aggravated by use and worse in the ring and little fingers. Examination demonstrated densely scarred skin on the palmar surface of the wrist with a positive Tinel sign here radiating to all fingers. Pin prick sensation was diminished to all fingers and two point discrimination increased 7, 9, 12, 20 + and 20 + mm. from thumb to little finger pulp. Significant muscle weakness was not present. A diagnosis of cicatricial ulnar and median neuritis at the wrist was made, but further neurolysis only seemed justified if the nerves could be separated from the grossly fibrosed overlying skin. No local skin flap was available. As arthritis combined with a nervous temperament excluded use of a distant skin flap, and free flap transfer was considered too lengthy an operation, a muscle flap seemed the best solution and abductor digiti minimi the obvious muscle. At operation extensive fibrosis was found involving ulnar and median nerves, skin and flexor tendons. Tenolysis with internal and external neurolysis was performed. Through a separate lateral incision the abductor digiti minimi was dissected free throughout its entire length (Fig. 1). The neurovascular bundle was found in the described proximo-radial site and preserved. The muscle was then tunnelled under the skin strip separating hypothenar and palmar incisions (Fig. 2), somersaulted to bring the tendon proximal, fanned out over the scarred nerves (Fig. 3) and buried beneath the skin. Post-operative progress was uneventful. Assessment showed loss of palmar pain, diminution of pain in the fingers and absent Tinel signs over the nerves. 84
The Hand--Vol. 9
No. 1
1977
The ,4 bductor Digiti Minimi Muscle Flap --Timothy M. Milward, Wayne G. Stott, Harold E. Klelnert REFERENCES BRASH, J. C. (1955) Neuro-Vascular Hila of Limb Muscles. Edinburgh, E. & S. Livingstone Ltd. GER, R. (1966) The Operative Treatment of the Advanced Stasis Ulcer. A Preliminary Communication. American Journal of Surgery, 111: 659-663. HUBER, E. (1921) Hilfsoperation bei Medianusl~ihmung. Deutsche Zeitschrift fur Chirurgie, 162: 271-275, LITTLER, J. W. and COOLEY, S. G. E. (1963) Opposition of the Thumb and Its Restoration by Abductor Digiti Quinti Transfer. The Journal of Bone and Joint Surgery, 45A: 1389-1396 and 1484. NI C OL A Y S E N , J. (1921) Nordisk Kirurgisk Forening F6rdhandlinger. p. 118. 13th Meeting, Helsingfors. NI C OL AY S E N , J. (1922) Transplantation des M. abductor dig. V. bei fehlender Oppositionsfahigkeit des Daumens. Deutsche Zeitschrift ftir Chirurgie, 168: 133-135. PERS, M. and MEDGYESI, S. (1973) Pedicle Muscle Flaps And Their Applications In The Surgery Of Repair. British Journal of Plastic Surgery, 26: 313-32l. S U N D E R L A N D , S. and HUGHES, E. S. R. (1946) Metrical And Non-Metrical Features Of The Muscular Branches Of The Ulnar Nerve. The Journal of Comparative Neurology, 85: 113-123. VASCONEZ, L. O., BOSTWICK Ili, J. and McGRAW, J. (1974) Coverage of exposed bone by muscle transposition and skin grafting. Plastic and Reconstructive Surgery, 53: 526-530.
The Hand--VoL 9
No. 1
1977
85
THE ABDUCTOR
DIGITI MINIMI
MUSCLE
FLAP
T I M O T H Y M. M I L W A R D , Leicester, W A Y N E G. STOTT, Melbourne, and H A R O L D E. K L E I N E R T , Louisville SUMMARY
The problems of extensive scarring involving the median and ulnar nerves at the wrist are discussed. Possible methods of separating the dermal cicatrix from the nerves are skin flaps or muscle flaps. A case is presented in which an abductor digiti minimi muscle flap was used. The reasons for this choice are discussed and the technique described. INTRODUCTION
Though muscle flaps have been used increasingly for the solution of lower limb skin cover problems since first described by Ger (1966) over a decade ago, their use in the upper limb has not been described and we would like to present one such flap that we' have found useful in the hand. There is the occasional patient who, following repeated carpal tunnel surgery, develops a vicious cycle of progressive dermal scarring, loss of subcutaneous fat, increasing constrictive fibrosis around median and ulnar nerves with symptoms tempting the surgeon to attempt further neurolysis. If surgery is to be undertaken with any hope of success, some new tissue must be introduced between scarred skin and nerves. Possibilities are the subcutaneous fat of a skin flap or a muscle flap as used in this case. The practicability of the muscle flap is now well established (Ger 1966, Pers 1973, Vasconez 1974) mainly from its use in lower leg defects where the flap is surfaced with a skin graft. Less attention has been paid to the technique in the hand because a distant skin flap is usually available. When for various reasons a skin flap is not advisable, a muscle flap should be considered. THE ABDUCTOR DIGITI MINIMI MUSCLE FLAP
Abductor digiti minimi is a muscle whose transfer potential was recognised early on. Huber (1921) and Nicolaysen (1922) used this ulnar innervated muscle for opponens plasty in isolated median nerve palsy. Littler and Cooley (1963) reported a further five cases using this technique successfully. It is particularly suitable as a donor muscle having a compact single neurovascular bundle of reliably constant position Huber (1921), Sunderland and Hughes (1946), Brash (1955) and leaving little functional defect as flexor digiti minimi substitutes for it. To obtain maximum mobility it needs to be completely freed from both origin and insertion leaving the neurovascular bundle as its sole attachment. This is in contrast to many long muscle tendon transfers and requires meticulous dissection to avoid compromising the blood supply. Littler and Cooley rightly stress that the method is technically difficult. Timothy M. Milward, F.R.C.S., The Leicester Royal Infirmary, Leicester, LEI 5WW. 82
The Hand--Vol. 9
No. 1
1977
The Abductor Digiti Minimi Muscle Flap --Timothy M. Milward, Wayne G. Stott, Harold E, Kleinert
CASE REPORT
In 1970 a sixty-nine year old woman sustained a Colles' fracture to the right wrist. Following closed reduction and plaster casting she developed acute carpal tunnel compression. This was treated surgically at three weeks with decompression, ulnar head excision and both internal and external neurolysis of ulnar and median nerves. Subsequent hand swelling and scalding wrist pain were thought to be Sympathetic Dystrophy and were treated by a stellate sympathectomy in early 1971 without relief. In late 1971 due to the persistent symptoms
Fig, 1. Abductor Digiti Minimi muscle isolated on neurovascular pedicle.
Fig. 2.
Muscle tunnelled through into palm.
The Hand--Vol. 9
No. 1
1977
83
The Abductor Digiti Minimi Muscle Flap --Timothy M. Milward, Wayne G. Stott, Harold E. Kleinert
Fig. 3. Muscle fanned out over median and ulnar nerves. the area was re-explored with no improvement. In 1975 the patient first came under our care. At that time her complaint was of an icy-cold sensation in the hand aggravated by use and worse in the ring and little fingers. Examination demonstrated densely scarred skin on the palmar surface of the wrist with a positive Tinel sign here radiating to all fingers. Pin prick sensation was diminished to all fingers and two point discrimination increased 7, 9, 12, 20 + and 20 + mm. from thumb to little finger pulp. Significant muscle weakness was not present. A diagnosis of cicatricial ulnar and median neuritis at the wrist was made, but further neurolysis only seemed justified if the nerves could be separated from the grossly fibrosed overlying skin. No local skin flap was available. As arthritis combined with a nervous temperament excluded use of a distant skin flap, and free flap transfer was considered too lengthy an operation, a muscle flap seemed the best solution and abductor digiti minimi the obvious muscle. At operation extensive fibrosis was found involving ulnar and median nerves, skin and flexor tendons. Tenolysis with internal and external neurolysis was performed. Through a separate lateral incision the abductor digiti minimi was dissected free throughout its entire length (Fig. 1). The neurovascular bundle was found in the described proximo-radial site and preserved. The muscle was then tunnelled under the skin strip separating hypothenar and palmar incisions (Fig. 2), somersaulted to bring the tendon proximal, fanned out over the scarred nerves (Fig. 3) and buried beneath the skin. Post-operative progress was uneventful. Assessment showed loss of palmar pain, diminution of pain in the fingers and absent Tinel signs over the nerves. 84
The Hand--Vol. 9
No. 1
1977
The ,4 bductor Digiti Minimi Muscle Flap --Timothy M. Milward, Wayne G. Stott, Harold E. Klelnert REFERENCES BRASH, J. C. (1955) Neuro-Vascular Hila of Limb Muscles. Edinburgh, E. & S. Livingstone Ltd. GER, R. (1966) The Operative Treatment of the Advanced Stasis Ulcer. A Preliminary Communication. American Journal of Surgery, 111: 659-663. HUBER, E. (1921) Hilfsoperation bei Medianusl~ihmung. Deutsche Zeitschrift fur Chirurgie, 162: 271-275, LITTLER, J. W. and COOLEY, S. G. E. (1963) Opposition of the Thumb and Its Restoration by Abductor Digiti Quinti Transfer. The Journal of Bone and Joint Surgery, 45A: 1389-1396 and 1484. NI C OL A Y S E N , J. (1921) Nordisk Kirurgisk Forening F6rdhandlinger. p. 118. 13th Meeting, Helsingfors. NI C OL AY S E N , J. (1922) Transplantation des M. abductor dig. V. bei fehlender Oppositionsfahigkeit des Daumens. Deutsche Zeitschrift ftir Chirurgie, 168: 133-135. PERS, M. and MEDGYESI, S. (1973) Pedicle Muscle Flaps And Their Applications In The Surgery Of Repair. British Journal of Plastic Surgery, 26: 313-32l. S U N D E R L A N D , S. and HUGHES, E. S. R. (1946) Metrical And Non-Metrical Features Of The Muscular Branches Of The Ulnar Nerve. The Journal of Comparative Neurology, 85: 113-123. VASCONEZ, L. O., BOSTWICK Ili, J. and McGRAW, J. (1974) Coverage of exposed bone by muscle transposition and skin grafting. Plastic and Reconstructive Surgery, 53: 526-530.
The Hand--VoL 9
No. 1
1977
85