MARCH 1984

VOLUME 9A, NUMBER 2

Official journal AMERICAN SOCIETY FOR SURGERY OF THE HAND

THE JOURNAL OF

HAND SURGERY

AMERICAN VOLUME

ORIGINAL COMMUNICATIONS

Polydactyly of the thumb: A surgical plan based on ninety-five cases

Preaxial polydactyly constitutes the most common group of congenital anomalies of the hand

among the Chinese population of Hong Kong. Ninety-five cases from the Orthopaedic/Plastic and Reconstructive Surgery Unit, Princess Margaret Hospital, Hong Kong (March 1976 to March 1981), were reviewed. The cases were classified according to Wassel's classification (1969) into seven types. The most common category was type IV followed by types II, V, III, VII, I, and VI. The treatment of each type was analyzed. Bilhaut's procedure was satisfactory for type I, and a modified technique was used for types II and III. A method of shaving the incongruous articular cartilage was used in type IV. Removal of the extra digit and osteotomy of the metacarpal usually were required for type V. The experience with types VI and VII was too limited for assessment. Short-term results (1 to 6 years) have been satisfactory, but follow-up until skeletal maturity to assess the ultimate functional and cosmetic results is necessary. (J HAND SURG 9A:155-64, 1984.)

J. C. Y. Cheng, F.R.C.S.(E), F.R.C.S.(G), K. M. Chan, F.R.C.S.(E), F.R.C.S.(G), G. F. Y. Ma, F.R.C.S.(E), and P. C. Leung, M.S., F.R.A.C.S., F.R.C.S.(E), Hong Kong

Preaxial polydactyly (or duplication of the thumb) is a common entity in the group of congeni-tal upper limb anomalies. 1-7 Many years ago, surgeons believed that supernumerary thumbs presented no sur-gical problem and could be treated by simple ablation. Over the past decade, however, increasing knowledge on the basic pathoanatomy of this condition has changed these concepts. The need for careful consid-eration of each individual tissue component during re-construction has now been well established. The few reports mostly refer to experience with hands of white people. I. 5. 8. 9-12

From the Department of Orthopaedic and Traumatic Surgery. Chinese University of Hong Kong, Hong Kong.

Received for publication Jan. 20, 1982; accepted in revised form March 16, 1983.

Reprint requests: Professor P. C. Leung, Department of Orthopaedic and Traumatic Surgery, Chinese University of Hong Kong, Shatin, N.T., Hong Kong.

In 1950, Handforthl3 reported a small series of 14 cases of polydactyly of the hand among southern Chinese with the aim of reviewing the incidence and treatment of this condition among this racial group in Hong Kong. We report a more comprehensive analysis of a much bigger series and suggest the best surgical treatment for the individual groups of this most com-mon congenital anomaly of the hand in the Hong Kong area.

Patients

In the 5-year period from March 1976 to March 1981), 326 patients with 396 congenital anomalies of the upper limb were seen in the Orthopaedic/Plastic and Reconstructive Surgery Unit of Princess Margaret Hospital, Hong Kong. Among these, 84 patients with 95 duplicated thumbs were studied (Table I). Each case was typed according to Wassel's5 classifi-cation.

THE JOURNAL OF HAND SURGERY 155

156 Cheng et al .

Fig. l. Schematic drawings of the modified Bilhaut technique in a type III case.

\

Fig. 2. Schematic drawings of cartilage shaving procedure for a type IV case.

General principles of management

All the duplicated thumbs were treated surgically. The aim of surgical management was to preserve or rebuild one good functional thumb with normal appear-ance from two abnormal ones. We believe that success-ful reconstruction can be achieved only by giving spe-cial attention to each individual tissue, and our surgical procedures were guided by the following general prin-ciples.

Skin coverage. Usually there was ample skin avail-able for tissue coverage after removal of the extra digit. Care must be taken to avoid a linear scar that might lead to longitudinal contractures. Closure with Z-plasties was a simple and effective means of preventing con-tractures. Subcutaneous tissues should not be excised excessively at the pulp region because these tissues give good padding and help to match the size of the opposite thumb.

Deformity. Correct alignment of the retained com-ponent is the only means of preventing progressive an-gular deformity with growth. This can be achieved by adjusting the tension of the joint ligaments, creating more congruous articulating surfaces, or correcting bony angulation by osteotomy.

Joint. When duplication involves the joint itself

The Journal of HAND SURGERY

Table I. Classification of 396 congenital upper limb anomalies among the Chinese population in Hong Kong

%of No. of No . of involved

Type* Diagnosis patients limbs limbs

Failure of fonnation 39 44 11.1 II Failure of differen- 99 119 30

tiation III Duplication 143 158 39.9 IV Overgrowth 2 2 0.5 V Undergrowth (pure 6 8 2

hypoplasia) VI Constriction band 13 18 4.5

syndrome VII Generalized skeletal 24 47 11.9

disorder

Total 326 396 100

'Wassel's classification.

(types II, IV, and VI), a cartilaginous ridge is usually found separating the two articulating surfaces. Shaving of the cartilage ridge may allow the digit to be retained to be shifted to the correct functional position. The stability of the joint depends very much on careful ad-justment of the joint capsule and the collateral liga-ments. Reinforcement can be achieved by means of accessory tendons, e.g., the extensor tendon on the extra thumb and/or its abductor insertion. Temporary fine Kirschner wire transarticular fixation may help to maintain the correction.

Tendons. The flexor and extensor tendons (the latter in particular) should be centralized, and the insertion of the intrinsic thenar muscles should be kept on the re-tained digit to provide the proper strength and function of the reconstructed thumb.

Based on these surgical principles, we provided the following treatment methods for each group of our patients:

Type I. Bilhaut'sl4 procedure was used for symmet-ric bifid distal phalanx . The central wedge resection of the distal segment (soft tissue, nail, and distal phalanx) was followed by a wire loop approximation of the two bony components. Accurate suturing was performed on both the pulp and the nail. For the asymmetric type I bifid thumb, only the small component was excised.

Type II. Duplication at this level was usually asym-metric. The less functional radial component was re-moved while preserving the collateral ligament, which was then reattached to stabilize the joint. The extensor and flexor tendons were centralized in Hatt's fashion when indicated. Shaving of the cartilage ridge was sometimes indicated for a better alignment. Cases of

Vol. 9A, No.2 March 1984

Table II. Associated congenital anomalies

Anomalies

Syndactyly

Clinodactyly Floating thumb Congenital club foot Congenital heart disease

Inguinal hernia Anal stenosis Congenital deafness

No. of anomalies

I 3 2 3 5 2

symmetric type II bifid thumbs can also be managed with Bilhaut's technique.

Type m. Asymmetric duplication at this level was corrected by the use of a modified Bilhaut's technique (Fig. O. Like the other types, the radial component usually was not as well developed as the ulnar one. If the bony skeleton on the radial side was removed while retaining the radial portion of soft tissue and nail, this latter portion of tissue could then be used effectively in the Bilhaut fashion to form a better thumb with the full ulnar skeletal component. This newly reconstructed thumb matched the normal thumb better. Sometimes, osteotomy at the proximal phalangeal level was used to realign the distal phalanx, and plication and reinforce-ment of the radial collateral ligament were necessary to prevent ulnar deviation of the reconstructed thumb. The flexor and extensor tendons were centralized likewise on the retained component. Immobilization and tempo-rary stabilization were secured again with a longitudi-nal Kirschner wire. The pulp and nail of the new thumb possessed good function and appearance.

Type IV. In this most common group, one of the most common complications after excision of the un-wanted digit was the persistent ulnar deviation of the retained digit. In order to avoid this complication, we found that all possible means of reinforcing the stabil-ity of the metacarpophalangeal (MP) joint are essen-tial. These included plication of the capsule and collat-eralligament, reattachment of the extensor tendon from the removed component to strengthen the radial side, and sometimes a wedge osteotomy at the metacarpal level.

Since there is a cartilaginous ridge on the metacarpal head separating the two articulating surfaces of the common joint, shaving of this ridge to create one con-vex spherical articulating surface ensures a desirable position of the retained proximal phalanx on the meta-carpal. Whatever is done, temporary fixation with a Kirschner wire is usually desirable for a period of 3 to 4 weeks or more. The cartilage shaving is performed

Polydactyly of thumb 157

Table III. Wassel's typing for the present series

Wassel's No. of % of type thumbs total

6 6.3 II 16 16.8

III 9 9.4 IV 44 46.3 V II 11.6

VI 3 3.2 VII 6 6.3

Total 95 100

in the fashion advocated by Tada et al./6 in Japan (Fig. 2).

Some variations of type IV duplications demon-strated an ulnar deviation at the interphalangeal (lP) joint level after excision of the extra digit. This can be dealt with by capsular and collateral ligament plication or osteotomy, preferably at a separate, later session.

Type V. Removal of the unimportant component was usually straightforward. The tendons of the sacrificed thumb can be used to reinforce the radial collateral ligament of either the MP or IP joints to prevent ulnar-deviation. However, in certain cases where marked ulnar deviation of the retained thumb was present, a wedge osteotomy at the metacarpal and/or proximal phalanx level might be indicated.

Type VI. Like type V, removal of the radial compo-nent is usually sufficient, but here, plication of the ra-dial collateral ligament of the carpometacarpal joint is essential for stability. Great care must be taken not to damage the insertion of the abductor policis longus, otherwise repair or reattachment would be necessary.

Type VII. Excision of the extra digit containing the triphalangeal portion was done in three cases. In three other cases, the delta-phalanx present in the component to be retained was excised. The stability and alignment of the IP joint were ensured with capsular and collateral reinforcement in addition to prolonged immobilization with a Kirschner wire. In one adult, the "proximal interphalangeal joint" was arthrodesed after shortening the adjacent segments, and a thumb of matching length was reconstructed.

Results

Most of the patients were seen soon after birth. Nevertheless, 17 patients (10%) were seen as adults, and the oldest patient, 60 years old, sought treatment because his grandchildren disliked the appearance of his hand.

Twelve patients (13%) had a known family history of duplicated thumbs, and 18 patients (21.4%) were found

158 Cheng et al.

Table IV. Subjective assessment

No. of No . of thumbs in thumbs

Functional result No. of thumbs Not

The Journal of

HAND SURGERY

Cosmetic result

Not Type series operated assessed Satisfactory satisfactory Satisfactory satisfactory

I 6 4 II 16 12

III 9 9 IV 44 37 V II 9

VI 3 2 VII 6 6

Total 95 79

Percentage

Table V. Objective assessment

Criteria

Segmental alignment IP joint deviation: radial or ulnar MP joint deviation: radial or ulnar

Joint stability (passive joint deviation)

Ulnar instability at: IP joint MP joint

Radial instability at: IP joint MP joint

Joint mobility (active range of motion) IP joint MP joint

Thumb web (compare with opposite hand) Pulp condition

Nail condition Residual prominence at excision site Opposition and chuck pinch

Total

3 9 7

30 6 3 6

64

100%

2

< 10 < 25

< 5 < 20

< 5 < 20

> 70 > 70

Nonnal Nonnal

Nonnal Nil

Nonnal (6 points)

30

to have one or more associated congenital anomalies, some of which are listed in Table II. There were 51 male patients and 33 female patients, a male/female ratio of 1.55/1. The right hand was more frequently affected (right: left ratio of 55 : 40).

According to Wassel's classification, the most com-mon type in our series was type IV (86.3%), next came type II (16.8%), type V (11.6%), type III (9.4%), types I and VII (both 6.3%), and last, type VI (3.2%) (Table III).

Among the 95 thumbs, 16 were classified but not

3 0 9 0 7 0

29 1 6 0 3 0 6 0

63

98% 2%

Score (points)

1

10_20 25_50

5_15 20_40

5_15 20_40

50_70 50_70

< 20 Slightly smaller

than opposite nonnal thumb

Mild defonnity Mild

Mild impainnent of function

(3 points) -15

3 8 7

26 5 2 5

56

o

o 4

-8

87 .5% 12.5%

0

> 20 >50

> 15 >40

> 15 > 40

< 50 < 500

> 20 Marked atrophy or

tender

Grossly defonned Marked

Severe impainnent of function

(0 point) -0

operated upon. Two patients were reluctant to have surgery while the rest were considered too young at the time of this review. Sixty-four of the 79 patients that had surgery were available for assessment. The fol-low-up period ranged from 12 months to 6 years (with an average of 3 years and 7 months) .

Postoperative evaluation. The patients were as-sessed functionally and cosmetically at 12 months to 6 years after the surgery. patients and their parents were checked for their subjective feelings on both the func-tional and cosmetic results. For a better objective

Vol. 9A, No.2

March 1984 Polydactyly of thumb 159

Fig. 3A. The preoperative (left) and 2-year postoperative (right) appearance of the thumb in type I.

Table VI. Result of objective assessment

No. of No. of thumbs thumbs

Type in series operated

6 4 II 16 12

III 9 9 IV 44 37 V 11 9

VI 3 2 VII 6 6

Total 95 79

Percentage

"Good = 20 to 30 points, fair = 15 to 19 points. and poor =

160 Cheng et al . The Journal of

HAND SURGERY

Fig. 38. The preoperative (left) and 2-year postoperative (right) appearance of the thumb in type II.

Fig. 3C. The preoperative (left) and 2-year postoperative (right) appearance of the thumb in type III. Bilhaut's procedure. Note the scar along the nail and the nail bed.

involved the joints (i.e., types II, IV, VI, and VII) were found to have some degree of joint stiffness or instability, and type I cases had imperfect nails. Only five cases of types III and V did not appear to have residual defects at all.

However, if only those situations in which zero scores were given during the objective assessment were considered significant complications, only 14 out of the 64 hands assessed fell into this category. With the same criteria versus zero score situations in segmental align-

Vol. 9A. No. 2 March 1984 Polydactyly of thumb 161

Fig. 3D. The preoperative ( left) and 2-year postoperative ( right) appearance of the thumb in type IV.

Fig. 3E. The preoperative (left) and 2-year postoperative (right) appearance of the thumb in type V.

ment, Jomt instability, stiffness, narrowed first web space, and marked residual prominence, more compli-cations were found (Table VII) .

Discussion

Considering the importance of the thumb in grasp, pinch, and dextrous movements, polydactyly of the thumb must be a particularly significant congenital anomaly of the hand. It has a high incidence of between

10% to 20% of congenital hand anomalies in Western literature. I , 5

Handforth l3 was the first to show that this anomaly was particularly common among the Chinese. Our series of 326 cases of congenital upper limb anomalies confirmed that it was the most common hand anomaly among the local Chinese population. 7

Our most common group was Wassel's type IV (46 .3%). In comparison with Wassel's and Flatt's

162 Cheng et al.

Table VII. Complications of surgical treatment

No. of cases by type

The Journal of HAND SURGERY

Complication I I II I 11/ I IV I V 1 VI 1 VII Total cases

Segmental malalign-ment Deviation of IP joint

(>20) Deviation of MP joint

(>50) Joint instability (passive

lateral deviation) IP joint (> 15) MP joint (>40)

Joint stiffness (active range of motion) IP joint 50) MP joint 50)

Narrowed first web space (>20)

Marked residual promi-nence at site of du-plication

3

series, we had much fewer type VII cases whereas the order of distribution for types II, V, and III was similar.

Surgical correction should be performed before school age. A small, soft tissue appendage can be re-moved very early, but the optimum time of surgery for the other types usually is considered to be age I to 2 years, when surgical handling of the tissues becomes easier and the child is more cooperative in the rehabili-tation program. Parental anxiety over the function of the child's hand has moved us toward the earlier time for operation.

As 18% of our patients were first seen as adults, it is possible that the social stigma associated with an exter-nal congenital anomaly that influenced their parents against surgery still exists.

It is now well established that simple ablation is very often too simple for the treatment of polydactyly of the thumb. Careful planning is mandatory to assess the function of each component before deciding on which component is to be excised. Observation of the child at play and information from the parents are as important as the clinical assessments. Reconstruction should be aimed at both functional and cosmetic results that will match the normal thumb as much as possible, although the patients and their parents should understand that such results may not be possible.

An analysis of the results at 12 months to 6 years after surgery indicated that 98% of our patients and/or

2

2

4 2

3

3

2 3

7 2 3

4

their parents were satisfied with the functional results and 88% with the cosmetic results. One patient with type IV deformity was unhappy with the function be-cause the marked radial deviation of the IP joint im-paired function. Seven other patients complained of deviation of the thumb, which they considered cosmet-ically unsatisfactory. In fact, some of the reconstructed thumbs appeared smaller than the opposite normal ones, but few patients seemed upset with this im-balance.

Our observation on the growth of the split epiphysis in the nine cases did not reveal any definite abnormal-ity. Serial radiographs in the follow-up period did not show any significant unequal growth of the epiphysis or any evidence of epiphysis necrosis (Fig. 4). The ra-diographs showed the ossification centers united, and because of the equal growth of the two components, premature arrest of the epiphysis was avoided. How-ever, the longest follow-up was only 5 years. Only long-term follow-up to skeletal maturity can provide the ultimate answer. We have been most concerned with the effect of splitting an open epiphysis, but the available literature on split epiphysis8 14. 16 is limited and there is insufficient information on its long-term effect.

Shaving of the cartilage ridge, mainly for the type IV and sometimes for type II cases, in accordance with the description by Tada et al. 16 apparently gave satisfactory alignment. Follow-up radiographs did not reveal any

Vol. 9A, No.2 March 1984

Fig. 4. Result of split epiphysis by Bilhaut's procedure at 5-year follow-up . Result of fusion is not perfect, but there is no necrosis of the epiphysis .

disturbance in the growth of the epiphysis (Fig. 5). This technique is recommended whenever indicated .

Our experience with Bilhaut's procedure in type I and type III suggested that the approximation of the two bony halves might be technically difficult. We have modified this technique by totally sacrificing the bony appendages of the extra thumb, and while retaining the soft tissue, a central triangular wedge is resected. Then the cut edges are approximated by stitching back in Bilhaut's fashion (Fig . 1) . The appearance and function of the reconstructed thumb were apparently excellent. Further experience with this technique is required be-fore recommending it for general use.

We attempted to devise a comprehensive system of postoperative assessment by considering the multiple criteria of stability, alignment, mobility, quality of the pulp, the nail, and the overall function of the thumb. In 86% of the cases, results were categorized as "good." The groups with "fair" and "poor" scores were also unhappy with the cosmetic appearance of their recon-structed thumbs.

The functional and cosmetic defects were mainly caused by the severe ulnar deviation of the MP joint (>50) and radial deviation of the IP joint (>20) in type IV cases. Milder deviations of the MP joint (25 to 50) and IP joint (10 to 20) were found in another 10 patients (15%), but the overall thumb function was not affected . We feel strongly that the plication of the cap-

Polydactyly of thumb 163

Fig. 5. Preoperative (A) and postoperative (B) radiographs (2 years): Radiologic appearance of a type IV case treated with cartilage shaving procedure . The MP joint remains stable and the metacarpal head round.

sule, reinforcement with accessory tendons, shaving of the cartilage ridge, and Kirschner wire fixation for 4 weeks are important steps in the reconstruction of the joint.

Severe stiffness of the IP joint (range of movement less than 50) was encountered in seven patients (10%), particularly in type IT and type IV. The MP joint ap-parently regained better mobility when only three type IV patients (5%) had a range of movement of less than 50.

The quality of the pulp and nail was found to be very good in all the patients in whom the Bilhaut and the modified Bilhaut technique were used.

Triphalangism in polydactyly was the second most common type in most reported series . Wassel's series described a 20% incidence. Wood9 10 reviewed this entity extensively and recommended that treatment should be commenced early with removal of the radial digit , excision of all accessory parts including the delta-bone when present, reconstruction of joint liga-ments, and osteotomy for deviation.

In our series, triphalangism associated with polydac-tyly was present in only four cases of which two had bilateral involvement. These cases were often associ-ated with other anomalies. Syndactyly occurred in one, and a dangling thumb in another. One patient also had congenital deafness and anal atresia. We have followed closely the management methods advocated by others but are disappointed to find that we have failed to achieve good results in both segmental alignments and

Cheng et al.

joint functions. However, our experience with this problem is very limited.

REFERENCES

1. Flatt AE: The care of congenital hand anomalies. St. Louis, 1977, The CV Mosby Co

2. Barsky AJ: Congenital anomalies of the hand. J Bone Joint Surg [ Am] 33:35-64, 1951

3. Kelikan H: Congenital anomalies of the hand. J Bone Joint Surg [Am] 39: 1002-19, 1249-66, 1957

4. Yamaguchi H: Congenital anomalies of the hand. In Pro-ceedings of the Sixteenth Annual Meeting of the Japanese Society for Surgery of the Hand, Fukuoda,

1973 5. Wassel HD: The results of surgery for polydactyly of the

thumb. Clin Orthop 64:175-93, 1969 6. Lamb OW, Wynne-Davies R, Soto L: An estimate of the

population frequency of congenital malformations of the

upper limb. J HAND SURG 7:557-62, 1982 7. Leung PC, Chan KM, Cheng JCY: Congenital anomalies

of the upper limb among the Chinese population in Hong

Kong. J HAND SURG 7:563-5, 1982

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HAND SURGERY

8. Hartrampf CR, Vasconez LO, Mathes S: Construction of

one good thumb from both parts of a congenital bifid thumb. Plast Reconstr Surg 54:148-52, 1974

9. Wood VE: Treatment of the triphalangeal thumb. Clin Orthop 120:188-200, 1976

10. Wood VE: Polydactyly and the triphalangeal thumb. J HAND SURG 3:435-43, 1978

II. Marks TW, Bayne LG: Polydactyly of the thumb: Ab-normal anatomy and treatment. J HAND SURG 3:107-16, 1978

12. Tuch BA, Lipp EB, Larsen 11, Gordon LH: A review of supernumerary thumb and its surgical management. Clin Orthop 125:159-67, 1977

13. Handforth JR: Polydactylism of the hand in southern Chinese. Anat Rec 106:119, 1950

14. Bilhaut M: Gerison d 'un pouce bifide par un nouveau pro-cede operatoire. Congress Francais de Chir 4:576, 1890

15. Millesi H: Deformations of the fingers following opera-tions for polydactylia. Klin Med 22:266, 1967

16. Tada K, Yonenobi K, Kurisaki E, Ono K, Egawa T, et al: Polydactyly-An analysis of 232 cases. J Jpn Orthop Assoc 54:121-34, 1980

Distal ulnar growth arrest

Four cases of arrest of distal ulnar physeal growth occurring in children ages 7 to 13 years had

follow-up for 2 to 10 years. Each patient developed bowing of the radial diaphysis, ulnar transla-

tion of the distal radial epiphysis, and increased ulnar angulation of the distal radiocarpal joint

surface. Growth discrepancies were documented in both the ulna (range 2.2 to 3.9 cm) and to a

lesser extent the radius (range 0.2 to 1.6 cm) when compared to the opposite forearm in each

patient. The progression of deformity appeared to be greatest during adolescence. Radial devia-

tion and pronation were limited to varying degrees in each case. No patient had significant pain or functional impairment, but the cosmetic appearance was always displeasing. Indications for

surgical treatment include increasing ulnar angulation of the distal radial articular surface,

progressive loss of motion, and displeasing cosmetic appearance. (J HAND SURG 9 A: 164-71, 1984.)

Owen A. Nelson, M.D., Capt., MC, USAF,* James R. Buchanan, M.D.,* and C. Scott Harrison, M.D., ** Carswell AFB, Texas, and Hershey and Harrisburg, Pa.

From the Division of Orthopaedic Surgery, *The Milton S. Hershey Medical Center of The Pennsylvania State University, Hershey, Pa., and **Harrisburg Hospital, Harrisburg, Pa.

Presented at the annual meeting of The Society of Air Force Clinical Surgeons, San Antonio, Texas, May 3, 1983.

Received for publication Jan. 28, 1983; accepted in revised form May 3, 1983.

Reprint requests: Owen A. Nelson. M.D., Capt., MC, USAF, United States Air Force Regional Hospital Carswell, Carswell AFB, TX 76127.

164 THE JOURNAL OF HAND SURGERY

Fractures of physes account for about 15% of all fractures in growing children l - 3 with frac-tures of the distal radius accounting for nearly half of this group. By contrast, fractures of the distal ulnar physis account for only about 5% of all physeal in-juries.4 Of 196 fractures of the distal ulnar physis re-ported in the literature,!' 2, 4-7 only 33 have sufficient follow-up to assess the ultimate function of the growth plate. Six of these patients, each with a displaced