Abductor digiti minimi opponensplasty in congenital radial dysplasia Satisfactory results were obtained in 20 of 21 abductor digiti minimi opponensplasties performed in children with congenital radial dysplasia. A modified technique left the muscle attached to the pisiform and did not require complete dissection of the neurovascular structures. An adequate subcutaneous tunnel was made to accept the transferred muscle and laxity of the ulnar collateral ligament of the metacarpal-phalangeal joint of the thumb, a consistent finding in patients with isolated aplasia of the abductor pollicis brevis and opponens pol/icis muscles, was repaired by imbrication and suture of one of the tendinous slips to the ulnar capsule.
Paul R. Manske, M.D., St. Louis, Mo., and H. ReIton McCarroll, Jr., M.D ., San Francisco, Calif.
Huberl and Nicholaysen,2 working independently, described the abductor digiti minimi transfer to restore opposition after median nerve injury and poliomyelitis in 1921. The muscle transfer received little attention until 1963 when Littler and Cooley 3 restored interest in this procedure. Riordan, Powers, and Hurd 4 suggested use of this transfer for patients with congenital absence of thenar muscles in their follow-up report on 12 of 18 patients . Wissinger and Singsen5 , 6 reported results in one patient with thenar muscle aplasia treated with this transfer. This report reviews our experience with the abductor digiti minimi muscle in patients with congenital radial dysplasia. Radial dysplasia refers to various anomalies of the preaxial border of the forearm and hand and may include skeletal deficiencies of the radius, the carpal scaphoid and trapezium, and the bones of the first and second rays .7 The associated muscles, ligaments, and neurovascular structures of the preaxial border of the forearm also may be affected. A variety of clinical conditions, which are popularly referred to as radial club hand, floating thumb , hypoplastic thumb, thenar muscle aplasia, etc., are a few of the many possible manifestations. From the Division of Orthopedic Surgery, the Department of Surgery, Washington University School of Medicine, SI. Louis, Mo. Received for publication March 6, 1978. Reprint requests: Paul R. Manske, M.D., Division of Orthopedic Surgery, Department of Surgery, Washington University School of Medicine, 4960 Audubon Ave., St. Louis, MO 63110.
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Material Since 1971 we have performed 21 abductor digiti minimi opponensplasty operations in 18 patients with congenital radial dysplasia. There were 11 female patients and seven male patients with 10 procedures of the left hand and II of the right. Three patients had bilateral operations. The age at the time of operation ranged from 18 months to 10 years, and averaged 4 years and 9 months. The patients have been followed an average of 37 months after operation, ranging from 5 to 68 months. None has been lost to follow-up. The patients were divided into three groups on the basis of their deformities (Table I). In 10 hands there was absence of the abductor pollicis brevis and opponens pollicis muscles and laxity of the metacarpalphalangeal joint of the thumb without other abnormalities of the extremity (group I). Five hands had aplasia of the thenar muscles in association with other anomalies of the radial structures (group II). Six hands had weakness of opposition following pollicization of the index finger for an absent or floating thumb (group III). Group I: Isolated thenar aplasia. In 10 patients there was aplasia of the abductor pollicis brevis and opponens pollicis muscles, and the thumbs lacked all functional opposition (Fig. I). These children usually were brought to the clinic for other orthopedic problems, including abnormalities of the opposite hand, and the patients and parents frequently were unaware of this subtle anomaly until it was pointed out. There were various manifestations of radial dysplasia in the oppo-
0363-5023/78/060552+08$00.80/0 © 1978 American Society for Surgery of the Hand
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553
Table I Associated upper extremity anomalies
Patient
Anomalies of opposite extremity
Additional operations
lTD 2JW
None None
3 BR
None
None Ulnar MP capsular imbrication (secondary procedure) None
4 KM
None
None
Radial club hand; absent thumb (see No. 18)
5 BO
None
None
6JV
None
None
None None None None Radial club hand Radial club hand Absent extensor tendons
None None None None Wrist centralization Wrist centralization; deepen thenar web space; RoyalThompson opponensplasty Release syndactyly; rotationalosteotomy 1st metacarpal "On-top-plasty"S index to thumb
Absent thumb and index ray (see No. 19) Radial club hand; floating thumb None Hypoplastic thumb Floating thumb None Radial club hand Radial club hand
7 8 9 10 II 12
LB BS RW MK SH MC
I II II
13 AS
II
Absent index ray; syndactyly thumb, middle, ring
14 DB
II
15 MO
II
Congenital amputation at proximal phalanx thumb, index, long Decreased thenar web space; unstable thumb MP joint
16 BS
III
Hypoplastic thumb
17 BS
III
Hypoplastic thumb
18KM
III
19BO 20 De 210C
III III III
Radial club hand; absent thumb Absent thumb and index ray Absent thumb Absent thumb
Dorsal pedicle flap to thenar web space; Arthrodesis MP joint; Index pollicization
Index pollicization; arthrodesis PIP pollicized finger Wrist centralization; index pollicization Long finger poHicization Index pollicization Index pollicization
Operations of opposite extremity
None Absent thumb
None None
Radial club hand
Wrist centralization; index pollicization Wrist centralization; index pollicization (see No. 18) Long finger pollicization (see No. 19) Wrist centralization; index pollicization None Index pollicization Excise floating thumb None Wrist centralization Wrist centralization; EIP opponensplasty
None
None
None
None
None
None
Hypoplastic thumb (see No. 17) Hypoplastic thumb (see No. 16)
Index pollicization; arthrodesis PIP pollicized finger (see No. 17) Index pollicization (see No. 16)
None (see No.4)
None (see No.4)
None (see No.5) Absent thumb None
None (see No.5) Index pollicization None
Legend: MP, metacarpal-phalangeal, PIP, proximal interphalangeal. EIP, extensor indicis proprius.
site hand in eight patients. All 10 of the hands in this group demonstrated laxity of the ulnar collateral ligament of the metacarpal-phalangeal (MP) joint upon exerting radial stress to the thumb . Pinching or squeezing was done by adducting the first metacarpal toward the second using the adductor pollicis muscle while flexing and radially deviating the phalanges at the MP joint (Fig. 2). All hands with isolated thenar muscle aplasia had this ligamentous instability. Group II: Thenar muscle aplasia with other radial anomalies. Five patients had congenital absence
of the abductor pollicis brevis and opponens pollicis muscles in addition to other anomalies of the radial structures of the affected extremity. The associated abnormalities as well as the associated operative procedures are described in Table I. One of these patients had laxity of the MP joint to radial stress, one had MP joint instability to both radial and ulnar stress, and three had no ligamentous laxity of the thumb. The opposite hand was normal in three of the patients, but there was a radial club hand deformity of the opposite extremity in two patients.
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The Journal of HAND SURGERY
Fig. 1. Abductor pollicis brevis and opponens pollicis muscle aplasia with no' functional opposition.
Fig. 2. Demonstration of ulnar collateral ligament laxity.
Group III: Weakness of opposition after pollicization. Six transfers followed pollicization of the index finger for an aplastic or nonfunctioning floating thumb. Even though the first dorsal and volar interosseous muscles had been attached to the lateral bands at the time of pollicization, as described by Milford 9 and Buck-Gramcko,IO these six had residual weakness that interfered with function. The opposite hand had manifestations of radial dysplasia in five patients.
transferred muscle. Care was taken to avoid dissection on the proximal and radial sides of the muscle where the neurovascular structures are known to enter. Because of the constant location of the neurovascular structures and the potential risk to the viability of the muscle if they are injured, these structures either were not exposed or were visualized but not isolated . A second incision was made over the dorsal radial aspect of the MP joint of the thumb and the muscle was passed through a large subcutaneous tunnel between the thumb incision and the proximal ulnar incision. It is important that the muscle glides freely in the tunnel and is not constricted by soft tissue. In approximately half of our cases, it was necessary to dissect a few fibers of muscle origin off the ulnar side of the pisiform in order to obtain adequate length through the tunnel. However, we do not recommend complete detachment of the muscle from its osseous origin. The method of inserting the transferred tendon at the MP joint depended on the patient's deformity (Fig. 4). In patients with thenar aplasia with other radial anomalies (group II), one of the transferred slips was sutured to the soft tissues at the radial aspect of the base of the proximal phalanx and the other to the extensor pollicis longus at the level of the MP joint, as recommended by Riorday, Powers, and Hurd. 4 In group I patients, the MP joint was stabilized by imbrication of the ulnar capsule in a pants-over-vest fashion. One of
Operative technique The operative technique was adapted from that described by Littler and Cooley 3 and Riordan, Powers, and Hurd. 4 The muscle was exposed through an incision which originated over the ulnar border of the proximal phalanx of the little finger and palm (Fig. 3). The incision curved radialward proximal to the MP joint to cross the wrist crease on the radial side of the pisiform. The tendinous insertions into the extensor hood and the proximal phalanx of the little finger were detached, retaining as much tendon length as possible. Starting distally, the muscle was dissected out of its fascial sheath to its origin at the pisiform. There was considerable variation in the ease with which the fibers of the abductor digiti minimi and the flexor digiti minimi brevis muscles could be separated. Consequently, in several of the operative procedures, some of the fibers of the flexor digiti minimi brevis were included in the
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Abductor digiti minimi opponensplasty
555
.":.~~~~~ / -~
..
A
~ •• ~
-----~~~--~S-,_;:~-~~ •• >C
\
T"doos lnar Arter~ and
Ulom Ad", o,d Nme
II
Ner"e
lFI Carpi Ulnoris
8
Tendons Ulnar
Arter~
and Nerve
~t~~ I
PiSlform J
Abductor DIQlti V
lnCOfPI Ulnaris
Fig. 3. Operative technique.
the tendinous insertions then was sutured to the radial capsule, but the other was sutured to the imbricated ulnar capsule as well as to the extensor pollicis longus tendon. When the opponensplasty followed pollicization (group III), one slip was sutured to the radial lateral band and the other to the central slip at the proximal interphalangeal (PIP) joint of the pollicized finger. After operation the thumb was held in opposition in a bulky dressing for 3 weeks. After removal of the dressing, the thumb was taped into opposition for an addi-
tional 3 weeks (Fig. 5) and the child was encouraged to use his hand. At 6 weeks after operation, all dressings were discontinued. Formal retraining of the transfer was not necessary. Results It is difficult to evaluate postoperative improvement
of opposition in young children. Specific measurements such as pinch strength are of little value since these measurements will improve as the hands grow even without operation. Additionally, the children are able
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The Journal of HAND SURGERY
Manske and McCarroll
GROUP
INSERTION OF ADQ TRANSFER
n
INSERTION
EPL Inser ti ng
Tendons
Ulnar MP Capsule
Insertion to
Insertion to EPL
Rodiol MP Capsule
ADO ADO
GROUP m INSERTION
GROUP I INSERTION
Pothciz.d
Finger EPL
Insertion to Rad iol Loterol Band _U~-T'"
( ~-
Imbrication of
Insertion to
Ulnar MP
EPL and Ulnar MP
Capsule
\
(j)
Insertion to Central Slip
ADO
ADO
Fig. 4. Method of tendon insertion at thumb metacarpal-phalangeal joint.
Fig. 5. Postoperative taping of thumb in opposition .
to perfonn trick movements to compensate for their muscle deficiency . Consequently, the postoperative evaluation must be expressed in qualitative rather than quantitative terms. In 20 of the 21 patients, the transferred abductor digiti minimi muscle contracted and pulled the thumb into opposition usually by 6 to 8 weeks after operation (Figs. 6 and 7). There was improvement in the appearance of the hands, as well as improvement in the dexterity, strength, and usefulness of the thumb (Figs . 8 and 9). The unsuccessful transfer occurred in a patient in group III who developed a postoperative flexion contracture and limited extension at the basal joint of the thumb . Although contractions of the transferred muscle could be palpated, there was limited extension of the thumb secondary to partial fibrosis of the transferred muscle. We attribute the failure to a combination of factors . In this patient the neurovascular structures had been dissected out at the time of operation, the muscle released from its origin at the pisiform, and the muscle
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Figs. 6 and 7. Abductor digiti minimi transfer contracting and pulling thumb into opposition. passed through an inadequate subcutaneous tunnel. Eight of the 10 patients in group I and the one patient in group II with preoperative ulnar collateral laxity had postoperative stability of the MP joint with stress to the ulnar collateral ligament of the thumb (Fig. 10). The ulnar capsule of the two unstable thumbs had not been imbricated at operation. In one of these, imbrication was performed subsequently and the thumb now is stable. We recommend capsular imbrication and suturing of the transferred tendon to the ulnar capsule for group I-type patients.
Discussion Although the abductor digiti minimi transfer originally was described for median nerve injuries and thenar muscle paralysis, it is ideally suited for opposition weakness associated with congenital radial dysplasia. The abductor digiti minimi muscle is not involved in the dysplastic condition and is an available muscle in a hand which frequently has a limited number of transferable muscles. The transferred muscle improves the appearance of the hand by adding mass to the thenar eminence at the site of the congenitally deficient muscles . The abductor digiti minimi has the same amplitude and is synergistic with the abductor pollicis brevis and opponens pollicis muscles that it is replacing. Following transfer it pulls in the proper direction and it is not necessary to construct a pulley in order to obtain
Fig. 8. Postoperative functional improvement of thumb. proper function. There is no significant loss of little finger abduction following this transfer, since the extensor digiti minimi also can abduct the little finger. Littler and Cooley felt that the procedure required a refined surgical technique because of the potential risk to the neurovascular pedicle. We feel the risk is mini-
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HAND SURGERY
Fig. 9. Postoperative functional use of thumb .
Fig. 10. Postoperative ulnar collateral ligament stability.
mized by not completely dissecting out the neurovascular structures which consistently enter the muscle on the radial side at its origin. 11. 12 Since we do not detach these muscles completely from the pisiform, it is not necessary to isolate these structures at the time of operation. Leaving the muscle attached to the pisiform prevents excessive tension on the neurovascular pedicle as the muscle is passed through the subcutaneous tunnel. The vascular supply to the muscle probably was compromised in the patient with the postoperative flexion contracture. In this patient we released the muscle from its origin, exposed the neurovascular structures, and passed the muscle through a narrow subcutaneous tunnel. Instability Df the MP joint from laxity of the ulnar collateral ligament was noted prior to operation in all 10 patients in group I. This is an associated abnormality found consistently with absence of the abductor pollicis brevis and opponens pollicis muscles. Riordan, Powers, and Hurd did not note this ligamentous instability in their review of 18 patients with thenar muscle hypoplasia, but Strauch and Spinner l3 did in 11 patients with "aplasia of the median innervated thenar intrinsic muscles," and Su, Hoopes, and Daniel14 reported a similar case. None of our patients had a congenital abnormality of the flexor pollicis longus tendon which accounted for the radial deviation deformity of the thumb as reported by Tupper. 15 Although children can perform trick movements which enable them to pinch, we feel the ligamentous instability should be corrected surgically. Our preferred method includes suturing one of the tendon slips to the ulnar side of the joint along with imbrication of the ulnar capsule . We do not understand the cause of this instability
completely . In support of it being congenital in origin, we did not find a specific ulnar collateral ligament at operation, but noted a thickened capsule. However, it is possible that the deficit is acquired as the result of an improper pinch pattern. The first metacarpal is stabilized in adduction by the adductor pollicis muscle, and pinch results in radial deviation of the thumb phalanges. However, neither of the two patients with postoperative ulnar collateral instability demonstrated any improved stability with time and growth, even though the pinch pattern was altered. In one patient the ligament was imbricated 30 months after the opposition transfer. The other patient remains unstable after 42 months. There were bilateral manifestations of radial dysplasia in 12 of the 18 patients. Frequently, parents are so concerned with the more obvious features of radial dysplasia of the one hand that the more subtle manifestations of the opposite hand, such as isolated thenar muscle aplasia, go unnoticed. One should be aware of this frequency of bilateral involvement in this condition and always carefully examine the opposite extremity. Riordan, Powers, and Hurd advise performing the muscle transfer when the patient is between 3 and 6 months of age, before the child develops fixed habit patterns in hand function . In spite of the fact that the average age at the time of operation in this series was 4 years and 9 months and that our youngest patient was 18 months of age , we have observed no difficulty in the ability of the children to develop new habit patterns and to use the transferred muscle. However, we agree that the operation should be performed as early as possible and we have not postponed it intentionally.
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Summary I. Satisfactory results were obtained in 20 of 21 abductor digiti rninirni opponensplasties performed in children with congenital radial dysplasia. The transfers improved both function and appearance of the hand. 2. The surgical technique described leaves the muscle attached to the pisiform and does not require complete dissection of the neurovascular structures. It is important to prepare an adequate subcutaneous tunnel to accept the transferred muscle. 3. Laxity of the ulnar collateral ligament of the MP joint of the thumb is a consistent finding in patients with isolated aplasia of the abductor pollicis brevis and opponens poIIicis muscles. Repair of the ligament by imbrication and suture of one of the tendinous slips to the ulnar capsule provided good joint stability. REFERENCES I . Huber E: Hilfsoperation bei Medianuslahmung. Dtsch Z Chir 162:271-5, 1921 2 . Nicholaysen J: In: Nordisk Kirurgisk Forenung Fochandlingar. 13th meeting, Helsingfoes, 1921, p 118 3. Littler JW, Cooley SGE: Opposition of the thumb and its restoration by abductor digiti quinti transfer. J Bone Joint Surg [AM] 45:1389-96, 1963 4. Riordan DC, Powers RC, Hurd RA: The Huber procedure for congenital absence of thenar muscle. Presented to Annual Meeting of American Society for Surgery of the Hand , San Francisco, Feb 27, 1975.,
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5. Wissinger HA, Singsen EG: Abductor digiti quinit opponens plasty. J Bone Joint Surg [Am 4 59:895-8, 1977 6. Singsen EG, Wissinger HA: Abductor digiti quinti opponensplasty. J Bone Joint Surg [Am] 58:727, 1976 7. Pardini AG: Radial dysplasia. Clin Orthop 57: 153-77, 1968 8. Kelleher JC, Sullivan JG, Baibak GJ, Dean RK: "Ontop-plasty" for amputated fingers . Plast Reconstr Surg 42:242-8, 1968 9. Milford L: In Crenshaw AH , editor: Campbell's operative orthopaedics, ed 5, The C V Mosby Co, St Louis , 1971, pp 278-80 10 . Buck-Gramcko D: Pollicization of the index finger. J Bone Joint Surg [Am] 53:1605-17, 1971 II. Sunderland S, Hughes ESR: Metrical and non-metrical features of the muscular branches of the ulnar nerve. J Comp Neurol 85:113-23, 1946 12 . Brash, JC: Neurovascular hila of limb muscles. Edinburg , 1955, E & S Livingstone, Ltd 13 . Strauch B, Spinner M: Congenital anomaly of the thumb: Absent intrinsics of flexor pollicis longus. J Bone Joint Surg [Am] 58: 115-8, 1976 14. Su CT, Hoopes, JE, Daniel R: Congenital absence of the thenar muscles innervated by the median nerve. J Bone Joint Surg [Am] 54:1087-90, 1972 15. Tupper J: Pollex abductus due to congenital malposition of the flexor pollicis longus. J Boint Surg [Am] 51: 1285-90, 1969
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