Hand

~~~RIGINAL

THE JOURNAL OF

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iation

;urgeD,handration tod the use

..,dactyly of the thumb: Abnormal anatomy and~atment

years 26 duplicated thumbs were seen in the hand clinic of a hospital for crippled children.classification based on the level and degree of duplication and a knowledge of the abnormal

reconstruction was done. This surgery was done with proper skin incisions, reconstruction ofcoll(~teral ligaments, centralization of the flexor and extensor tendons, and alignment of the bones

by corrective asteotomies. Simple ablation or incomplete correction produced complicationscontractures, increased angular deformities, unstable joints, and intrinsic weakness. In all

tthe p~:,ients, the appearance was improved, opposition was maintained, and postoperative function;:npaired.

)l. 3, No.

W. Marks, M.D., and Loui G. Bayne, M,D., Atlanta, Ga.

or duplication of the thumb, is a com-finomaly. A basic understanding of the abnormal

and some ingenuity are required for proper re-

,I in 1957, reported congenital anomalies occur-18.5/1,000 live births. Sesgin and Stark, 2 in

1; reportedpolydactylism in 1.0/713 live births.in 1971, reported his review from the University

with polydactylism of their hands.: were 255 digits involved. The thumb was the one:commonly involved, representing 113 of the in-

tigits. These statistics are impressive when onethe fact that duplicated digit.s seldom are

h Rite Children’s Hospital of George, Atlanta, Ga.for publication Feb. 7, 1977.

requests: Thomas W. Marks, M.D., 340 Boulevard, N.E.,545, Atlanta, GA 30312.

seen, except when they are concentrated in an areasuch as a hand clinic.

Embryology

Bardeen and Lewis,4 in 1901, described the develop-

ment of the appendages from the Primitive streak. Thearm bud develops from the mesenchyme at the level ofthe eighth myotome. The arm bud is apparent at thethird week of embryonic life. From this time until theeighth week of embryonic life, there is differentiationof the upper extremity. By the eighth week of embry-onic life, all of the components of the upper extremitieshave differentiated completely, including the distalphalanges of the fingers. If duplication is associatedwith insult to the embryo, the trauma must occur beforethe eighth week of embryonic life.

Etiology

The cause of polydactyly of the thumb is unknown.Experimeiatal studies by Bagg,5 in 1927, showed that

~/0203-0107501.00/o © 1978 American Society for Surgery of the Hand THE JOURNAL OF HAND SURGERY 107

TheHAND108 Marks and Bayne

Table I

Associated anomalies No. of cases

Asthma 1Diabeties mellitus 1Inguinal hernia 1Esophageal atresia 1Ventricular septal defect 2Syndactyly of fingers 3Supernumerary digitsFingers 1, bilaterallyGreat toes 2, bilaterallyPartial absence of index finger 1

injury with hemorrhage was associated with polydac-tyly in rats. Woolf,6 in 1970, concluded that the mostcommon type of preaxial polydactyly involving dupli-cation of the first digit was sporadic in origin and

concluded that it was a result of polygenes or of un-known exogenous factors. From a review of the litera-ture and our cases, it is thought several patterns ofinheritance can occur,r

Material

This report is based on a study of 25 patients with 26duplicated thumbs seen over a 9-year period in a handclinic for crippled children. There were eight dupli-cated distal phalanges. Fourteen thumbs were dupli-cated at the proximal phalangeal level. Four thumbswere duplicated at the metacarpal level. There was awide variation in the degree of duplication at eachlevel. However, the degree of soft tissue duplicationcorrelated well with the degree of bone duplication.There was equal involvement of the right and leftthumbs. The records did not reflect which hand wasdominant; however, it is interesting to note that theduplicated thumb was. present on the dominant hand intwo cases. Associated anomalies are listed in Table I.

In four patients there was a family history. Twopatients had cousins with duplicated thumbs. The fa-ther of one patient had a duplicated thumb. The motherof the one patient with bilateral deformities had iden-tical anomalies of both hands, including syndactylismand duplicated thumbs.

Classification

Millesi, 8 1967, grouped 14 cases of polydactyly ofthe thumb into five types. Wassel,9 in 1969, classified79 cases into seven types. With our cases being toovaried to place in this many different types, they havebeen grouped according to the level of duplication; thatis (1) distal phalanx, (2) proximal phalanx, and metacarpal. The triph.alangeal thumb and the thumbwith a delta phalanx have not been included. There

was a wide variation in the degree of duplicationeach level. Therefore, it has’been more appropriateus to consider the level of duplication and the degreeduplication at each level when considering a surgicplan. There are certain basic abnormalities to amiciat each level, and ingenuity at the time of omust be applied to deal with the varied degreeduplication.

Abnormal anatomical findings

Skin coverage was not a problem, providedhandling of the skin was carried out. Sensationcirculation were not problems because the ulnarponent usually was preserved or the neuro’,asculabundle was preserved. The tendons were duplicated ithe same degree as the bone. With angular deformthere was subluxation of the tendon and a tetheringfect which accentuated the angular deformity.duplicated flexor and extensor tendons usually had onone muscle. In only one or two cases did the duthumbs seem to have independent motor function.collateral ligaments had normal attachments to thespective components. There was no apparent laxitythe collateral ligaments which would contribute toangular deformity. Consequently, angularcould not be corrected by tightening of theligaments. If duplication began at a joint, the jointenlarged with angulation of the joint. Thewere perpendicular to the respective bone, buttilted from the long axis of the thumb to thedegree that the joint was angulated. When thereduplication at the metacarpal level, the thenarinserted on the radial component, regardless ofdegree of duplication of the metacarpal. The-muscles usually inserted into the ulnar component

Timing of operation ) ....The hand develops function as follows: grip

grasp at 4 to 7 months; thumb and index fingerat 10 to 12 months; voluntary release at 15months; and a functional pattern at 2 to 3age.s° It is preferable to operate on these patientsthey are 3 years of age. Since coordina{ed functi<the thumb does not appear until a child is 2 to 3age, waiting until the patient is 3 years of age willalter the function of the reconstructed thumb, an!this age the structures are larger, surgery iseasier, and the patient can follow instructions iapostoperative .rehabilitation period.

Treatment

Surgical treatment is based on the anatomicaltion--level of involvement and the degree of

3, No. 21978

Polydactyly of the thumb 109

Suture L~ne

Basically, treatment consists of removal of thefunctional part and reconstruction of the remain-

components. If function of the two components isaal, tlaen the appearance is considered. Transposition

digit to another may be required when there is a!xed quality Of duplication. The various tissues must!:dealt with independently.. Skin coverage has not

~lem. The skin may be dealt with by makingion in the recommended incisional line along

aspect of the thumb, using a Z-plasty, or bying a skin flap. Flexor and extensor tendons shouldcentralized. This may be done by transposition of

reconstruction of the tendons after redun-portions are removed, or by centralization whichoccur when osteotomies are done to align theand phalanges. If the tendons are not centralized,

joints are pulled in an abnormal direction and a dy-force is created which may cause subsequent de-

ns in ~. Collateral ligaments attached to their corre-phalanges need to be transferred to thephalanx to provide joint stability. The align-

~:..! ;~ of joints and the an~ular deformity of the phalan-~ ~ ~;’ ~ " ,, i h ses, is corrected.~ varia, ~!!i~.i:.i:?::ges, w~th their correspondm~ ep p y ....

"~" , ?:!i by weds, ......... ies ,,roximal to the det’ormitv. It tinslnv

,; ~,i,,~

--

Fig. 1. Symmetrical duplication of the distal phalanges.

is not done, the joints function in an improper axis, andwith epiphyseal growth, the angular deformity is ac-centuated. When duplication occurs at a joint, the headof the proximal phalanx or metacarpal is enlarged to ac-commodate the double articulation. A partial excisionof the bone may be done to reduce the bulk. Whenthere is duplication of the proximal phalanx or any partof the metacarpal, most of the intrinsic muscles attachto the radial component. These muscles/must be trans-ferred to the remaining component to provide properfunction and strength.

Examples of treatmentExample I: Symmetrical duplication of the distal

phalanges (Fig. 1). Bilhout-Cloquet procedure,u con-sisting of a central wedge resection of distal phalanges,has been described by Barsky.zz This procedure is in-dicated with the symmetrically duplicated distal pha-langes. The technique presents several problems. It isdifficult to take out sufficient bone to reduce the thumbto the normal size. The base of the proximal phalanx is

broad. Approximating the distal phalanges is difficultbecause of the broad head of the proximal phalanx andthe tightening of the collateral ligaments as the

110 Marks and BayneThe Jour~,~

HAND SURG

A. Divide the Septum or Cert.

Divide the Extend --- ",Preserve theFlex. Tendon I L~g "

-.Correct ~ngulation

¯ Hold Osteotomy

Fig. 2. Assymetrical duplication of the distal phalanx.

phalanges are approximated. This could not be accom-plished by transfixing K-wire and required circumfer-ential suture around the distal phalanges. The articular

¯ surface of the distal phalanges was involved, whichrequired accurate approximation. The epiphyses of thedistal phalanges also needed to be accurately reduced toavoid growth disturbance. The nail bed required accu-rate repair to reduce the size of the anticipated cleft ofthe nail. This procedure appears simple,, upon initialevaluation, but it is not an easy procedure.

Example H: Asymmetrical duplication of the dis-tal phalanx (Fig. 2). This deformity requires removalof the less functional component, which is usually theradial one. The collateral ligament should be trans-ferred to the remaining phalanx. The flexor and exten-sor tendons should be centralized. The angular deform-ity of the interphalangeal joint and distal phalanx iscorrected with an osteotomy of the distal end of theproximal phalanx. Fixation is obtained by using a K-wire. With correction of the angular deformity, theflexor and extensor tendons probably will be moved

into the longitudinal axis of the thumb, eliminatingneed for transposition of the tendons.

Example III: Duplication at thephalangeal level (Fig. 3). The radialusually is not developed as well as the ulnarnent. The extensor tendons are duplicated withmon hood. The flexor tendons are duplicated.an angular deformity, there is subluxation of theand extensor tendons. The collateral lithe respective proximal phalanx. The intrinsicattach to the radial component. Treatmentexcising the less dominant thumb, decreasing theof the distal articular surface of the metacarpaltransferring the collateral ligament to the remair~phalanx, advancing the intrinsic muscles to thema! phalanx, and doing an osteotomy of thebones to correct angular deformity. Immobilization.!obtained using a longitudinal K-wire.

Example IV: Duplication at the metacarpal le’(Fig. 4). The thenar muscles always attach to thecomponent regardless of the size of duplication

:ation

! 3, No. 21978

Polydactyly of the thumb 111

transfer to the remaining component. The othertechniques already described may be

Mixed quality of duplication (Fig. 5).radial thumb is crooked and small on the distal

base is well developed. Attached to it are thepollicis brevis, the flexor pollicis brevis, thepollicis, and the extensor pollicis brevis.

is good function at the base of the thumb, withlittle function of the proximal and distal

The ulnar component is straight and has fullof the flexor and extensor tendons. The

is developed incompletely and there is noor extrinsic muscle attachment at the base.

requires removal of the radial thumb ati metacarpal level and transfer of the ulnar compo-

to the base of the more radial metacarpal. The

Fig. 3. Duplication at the proximal phalangeal level.

extensor pollicis brevis, abductor pollicis brevis, flexorpollicis brevis, and adductor pollicis are transferred tothe transposed thumb. The flexor and extensor tendonsare transferred with the ulnar component.

Example VI: Inadequate thumb Web space (Fig.

6). The radial component is removed. The thumb webspace is inadequate, and reconstruction of the thumbweb space is accomplished by sliding a skin flap fromthe dorsum of the hand into the thumb web space. The

adductor muscles and first dorsal interosseous were-re-leased. The donor site was closed with a split-thickness

graft.

ComplicationsComplications consist of skin contracture, increased

angular deformity, unstable joints, and intrinsic weak-ness. Theseusually are associated with incomplete cor-

112 Marks and Bayne HAND

Subluxed Tendons

Intrin. Mus. Insertion fo~ ~. .Anguloted

PLICATION AT THEPROXIMAL PHALANGEAL

~ LffVEL

~~

Corr~t Angu/atlon

Fig. 3, con’t.

3, No. 2 Polydactyly of the thumb 1131978

Fig. 4. Duplication at the metacarpal level.

ion at the time of operation or with failure of theto return for subsequent steps of reconstruction.

In this series there are six patients who need an addi-procedure. Three of these need deepening of anuate thumb web space. The other three are

with duplication at thelevel of the proximalneed osteotomies of the proximal phalanx

the angular deformity of the interphalangealand distal phalanx.

~lications in this series consisted of (1) a stiff,interphalangeal joint in one case (An arthrod-

was done, resulting in a stable, painless joint.); (2)of the interphalangeal joint with adhesion of

extensor tendon and extension contracture of the in--joint occurred in one case (A tenolysis,

y, and a fascial graft were done. Thesein a painless interphalangeal joint with up to

of flexion.); (3) radial deviation of the distal pha-in one case (Reefing of the ulnar collateral

ligament was done without improvement of the angulardeformity. It has been our experience that angulardeformities cannot be corrected significantly by tight-.__ening of the collateral ligaments and a corrective oste-otomy is required.); (4) in one case, a central wedgeresection of the distal phalanges resulted in an im-proved appearance but the thumb wa~s still broad.

ResultsIn all of our patients, the appearance was improved.

The most striking improvement in function and appear-ance was in the thumbs with the more proximal dupli-cation. There was decreased range of motion of the

joints involved in the operation. The average postoper-ative range of motion of the interphalangeal joints was0° to 30° of flexion. Opposition was maintained, andafter operation function was not impaired. The patientand the patient’s parents were pleased with the

results.

114 Marks and Bayne

The JournalHAND SURG

Thumb Thumb

Fig..~g. Mixed quality of duplication.

Summary

Reconstructive surgery of supernumerary thumbsrequires a basic knowledge of the abnormal anatomy. Ifcorrection is inadequate, deformities can become ac-centuated by abnormal dynamic forces. The.. ultimategoal in the treatment of any congenital anomaly of theextremities is restoration of the normal anatomical rela-tionship of the remaining structures to the longitudinalaxis.

REFERENCES

1. Ivy RH: Congenital anomalies. Plast Reconstr20:400, 1957

2. Sesgin MZ, Stark RB: The incidence of confects. Plast Reconstr Surg 27:261, 196t

3. Flatt AE: Problems in polydactyly, in CramRA, editors: Symposium onthe hand, 1971,Mosby Co.; pp 150-167

(cont’d on p.

3, No. 2 Polydactyly of the thumb 1151978

Fig. 6. Inadequate thumb web space.

116 Marks and Bayne

4. Bardeen CR, Lewis WH: The development of the limbs,body-wall and back. Am J Anat 1:1-36, 1901-02

5. Bagg HJ: Hereditary abnormalities of the limbs; their ori-gin and transmission. Am J Anat 43-167, 1929

6. Woolf CM: A genetic study of polydactyly in Utah. AmJ Hum Genet 22:75-88, 1970

7. Snedecor ST, Harryman WK: Surgical problems in he-reditary polydactylism and syndactylism. J Med Soc NJ37:433, 1940

The JournalHAND SURGERy!

8, Mlllesi H: Fmgerverformmg nach Operat~onenPolydactylie. Klin Med (Weir0 22:266-72, 1967 .

9. Wassel HD: The results of surgery for polydactyly of the: i!i~]Ii ’,~ fthumb. Clin Orthop 64:175-93, 1969

10. Gesell A: The first five years of life, ed 1, New1940, Harper & Row, Publishers :!;

11. Barsky A: Congenital anomalies of the hand and theirsurgical treatment. Springfield, 1958, Charles C Thom-as, Publisher, pp. 63-64

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Most of the provisions of the Copyright Act of 1976 became effective on January l,1978. Therefore, all transmittal letters must be accompanied by the following statement,signed by each author: "The undersigned author(s) transfers all copyright ownership the manuscript entided (title of article) to the American Society for Surgery of the Handin the event the work is published. The author(s) warrants that the article is original, not under consideration by another journal, and has not been previously published."Authors will be consulted, when possible, regarding republication of their material.