Coflg. Anom., 26: 85-92, 1986

Original

Preaxial Polydactyly and Hallux Varus: Classification of Hallux

Varus and Relationship between Hallux Varus and Preaxial

Po I ydac t y I y

Takayuki MIURA, Ryougo NAKAMURA, Syuuhei TORII, Kazuharu HANAKI and Yuuji YOSHIHASHI Department of Orthopaedic Surgery, School of Medicine, Nagoya University, 65 Tsuruma-cho, Showa-ku, Nagoya 464, Japan

ABSTRACT The clinical features of 18 patients diagnosed as having preaxial polydactyly and hallux varus were studied.

There are three types of hallux varus: 1) the medial great toe is pushed out by the lateral overldpping great toe, 2 ) the great toe is inverted by the deformed first metatarsus, and 3) the great toe is inverted by anchoring substance of the hypo- plastic or degenerative medial great toe.

The general diagnosis of “hallux varus” may be reasonable based on the com- mon appearance, but the clinical features of these three types differ from each other. The patients with hallux varus caused by anchoring of the hypoplastic or degenerative medial great toe should be strictly differentiated from the patients with hallux varus due to deformity of the metatarsus. Special consideration for treatment is needed for each type. Key words: congenital anomaly, preaxial polydactyly, foot, hallux varus, meta- tarsal deformity, classification, therapy

Hallux varus is reported to be a comparatively rare congenital malformation and the details of its clinical features have not been clarified yet. The cases reported by Thomson (1960) showed an ad- duction deformity of the forefoot, and so the metatarsus is adducted without deformity of the meta- tarsus nor the presence of polydactyly. These features are quite different from the cases generally understood as hallux varus. The patients in the textbook of DuVries (1978) and in the report of Haas (1938) showed inversion of the great toe due to deformity of the first metatarsus. Although the report of Farmer (1958) involves patients with a deformed first metatarsus, some patients in his report have bifurcated great toes, and medial great toe is inverted without deformity of the first metatarsal bone. On the other hand, Sloane (1935) reported patients who had a major symptom of an inverted great toe and a widened first interdigital space; these patients are considered to be cases of true “hallux varus” in the strictest sense.

86 T. Miura e t al.

The clinical features of so called “hallux varus” can be quite different in each case. Therefore, there is a question of whether they can be treated as the same disease or not.

Hallux varus may be closely related to preaxial polydactyly because reports of “hallux varus” included many cases of preaxial polydactyly. Study of the clinical findings of 18 patients diagnosed as preaxial polydactyly and hallux varus may prove helpful in understanding the clinical features and establishing proper treatment.

CLINICAL FEATURES AND CLASSIFICATION

In 3 patients with bifurcation of the great toe from the IP joint or distal phalanges and inversion of the medial great toe, inversion was noted in 3 feet of 2 patients but not in 2 feet of one patient. On the other hand, in 2 patients with bifurcation from the proximal phalanges, all 3 feet of 2 patients showed no inversion except only slight deformity at the IP joint (Fig. 1). Five patients with bifurca- tion from the MP joint can be classified into two types on the basis of the shape of the first meta- tarsus. Two patients without deformity of the metatarsus showed no inversion or only slight inver- sion of the medial great toe (Fig. 2). On the contrary, in 5 feet of 3 patients (one foot of 1 patient had a bifurcation from the IP joint) the first metatarsus was deformed to trapezoid, and the great toe was inverted (Fig. 3). A younger brother of one patient showed bilateral inversion of the great toe by a trapezoidal deformity of the metatarsus without bifurcation of the great toe (Fig. 4). Simi- lar patients were reported by Farmer et al. Furthermore, the cousin of our patient showed bifurcated great toe, and the medial great toe was inverted due to a deformed first metatarsus. In 4 feet of 2 patients with a bifurcated great toe from the metatarsus, the medial great toe was apparently inversed, and a similar case was included in the report of Farmer. However, the inversion in these 2 patients was limited to the medial great toe (Fig. 5).

Fig. 1 Case 5, showing bifurcation from proximal phalanx, syndactyly, no remarkable inversion.

Preaxial polydactyly and hallux varus 87

Fig. 2 Case 6 , showing bifurcation from MP joint, syndactyly, no inversion

Fig. 3 Case 8, showing bifurcation from MP joint, syndactyly, hallux varus due to metatarsal deformity.

Fig. 4 Case 9, showing no polydactyly, hallux varus due to metatarsal deformity.

The 5 patients with complete separation of the metatarsus can be divided into two groups based on the degree of formation of the medial great toe. Three patients were diagnosed as hypoplastic and 2 patients as well-formed. The latter patients are classified as preaxial polydactyly due to the ac-

88 T. Miura et al.

Fig. 5 Case 11, showing bifurcation from metatarsal, characteristic inversion of medial great toe (left) no remark- able inversion of medial toe due to syndactyly (right).

Fig. 6 Case 1 3 , showing independent from metatarsal, no remarkable inversion.

companying symptoms but hardly distinguishable from postaxial or central polydactyly. Adduction (inversion) from the metatarsus is slightly noted in these patients, but hallux varus deformity is hard- ly observed (Fig. 6). On the contrary, apparent inversion is noted in the 3 hypoplastic patients, and their clinical features are interesting to consider in relation to the formation of true ‘hallux varus” in the narrowest meaning.

In case 16, the medial great toe was fairly formed, and there is no problem in diagnosing this as preaxial polydactyly. On the other hand, the interdigital space between the great toe and the second toe is widened, and thus diagnosis of hallux varus was confirmed (Fig. 7). In case 17, formation of the medial great toe is more hypoplastic than in case 16, and the metatarsus and phalanges are only traces on the X-ray film. The typical findings of hallux varus are noted: the great toe inverted and the first interdigital space widened (Fig. 8). Furthermore, in case 18, the medial great toe is noted only as a small elevation of soft tissue, and on the X-ray film no phalanx is noted but the proximal phalanges of the great toe showed a delta-phalanx suggesting the presence of polydactyly and syn- dactyly. However, it is difficult to diagnose this as preaxial polydactyly, and there is no problem to diagnosing it as hallux varus (Fig. 9a).

Preaxial polydactyly and hallux varus 89

Fig. 7 Case 16. Medial great toe is hypoplastic. There are widened interdigital space which is a characteristic feature of hallux varus.

Fig. 8 Case 17. Medial great toe is trace and interdigital space is widened.

When the patients were grouped on the basis of presence of syndactyly between the lateral and medial great toes or not, none of the patients with bifurcation from the phalanges with syndactyly showed inversion, but in the patients without syndactyly, inversion of the medial great toe was noted (Figs. 2, 3). However, this inversion was only limited to the medial great toe, so that the clinical features were different from those of true hallux varus in the strictest meaning. In the patients with bifurcation from the MP joint, regardless of syndactyly, the degree of inversion of the great toe(s) is decided by the shape of the first metatarsus. However, in patients without syndactyly even if the metatarsus was not deformed, there was inversion limited to the medial great toe. When syndactyly was not present, inversion of great toe due to morphological anomaly of the first metatarsus is clear-

90 T. Miura et al.

Fig. 9 Case 18. Proximal phalanx is a delta-phalanx suggesting polysyndactyly. Interdigital space is widened. This case is a typical hallux varus. a, b) Preoperative condition and skin incision. 2-plasty on medial side and two rotational flaps from inter- digital space are useful to elongate the medial side of hallux. c) Anchoring substance. Anchoring sub- stance of dysplastic or degenerated medial great toe must be excised. d) Postoperative condition.

ly observed at the medial great toe, and the degree of this inversion was related to the degree of metatarsal deformity. In patients with bifurcation from the metatarsus, although it was stated that inversion was noted only for the medial great toe, but in one patient with syndactyly the degree of inversion of great toe was slightly decreased compared with patients without syndactyly (Fig. 5). In patients with independent first metatarsal separation, inversion of the great toe was not observed as long as the formation of the medial great toe was good regardless of the presence or absence of syndactyly (Fig. 6 ) . On the other hand, when the medial great toe was hypoplastic, continuous range of variation was noted between preaxial polydactyly and hallux varus with typical features (Figs.

The diagnosis of “hallux varus” may be reasonable from its appearance but the clinical features of these patients can be grouped into three as follows: 1) The medial great toe only inverted by be- ing pushed out by the lateral great toe, 2 ) hallux varus caused by a deformed metatarsal bone, and 3) hallux varus caused by the presence of polydactyly and dysplastic change in the medial great toe, especially disturbance of metatarsal bone formation, and anchoring by the dysplastic or degenerated metatarsal bone.

7, 8, 9).

Preaxial polydactyly and hallux varus 91

T R E A T M E N T

For the first group, i.e., inversion of medial great toe being pushed out by the lateral great toe, the ordinary surgical procedure for polydactyly can be applied. In these patients, if the lateral great toe can be left, additional corrective osteotomy should be considered. If the medial great toe has to be left, the abductor muscles have to be elongated or translocated to proximal of the MP joint.

For the second group, in which the first metatarsus is deformed to a trapezoid, corrective oste- otomy of the metatarsus and realignment of the metatalsal and phalangal axis was effective.

Table 1 List of cases with preaxial polydactyly and hallux varus

Case Age Sex Side Characteristic Clinical Findings Familial

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1 1

18

2 2Y

l m

l m

3m

lY

3Y

2m

1 Y

3Y

3Y

l m

l m

8m

l m

l m

l m

l m

4m

F

F

F

M

F

M

F

M

F

M

M

M

F

M

F

M

M

M

B

B

B

B

L

B

L

B

B

B

B

B

B

B

R

L

R

R

IP bifurcation, no syndac, no invers dist bifur, no syndac, no inversion

IP bifur, no syndac, med toe invers

IP bifur, no syndac, med toe invers MP bifur, no syndac, med toe invers

prox bifur, syndactyly, no inversion

prox bifur, syndactyly, no inversion

MP bifur, syndactyly, no inversion

MP bifur, no syndac, med toe invers

MP bifur, metatar deform, inversion

MP bifur, metatar deform, inversion

no poly, metatar deform, inversion

metatar bifur, med toe inversion

metatar bifur, med toe inversion

independ metatar, develop, no invers

independ metatar, develop, no invers

central polydactyly (cleft foot ?)

med toe hypo, wide digit space, varus

med toe trace, wide digit space, varus

A-phalanx, wide digital space, varus

none

sisters

sisters

father, g-moth.

none

none

none

none

father, cousins

father, cousins

mother, cousins

none

mother, daught.

none

none

none

none

none

bifur: bifurcation from, syndac: syndactyly, metatar: metatarsus, hypo: hypoplastic, synd: syn- drome, varus: hallux varus, g-moth: grandmother,, wide digit space: digital space between big toe(s) and second toe is wide, prox bifur: bifurcation from proximal phalanx, med: medial, metatar deform: deformed metatarsus, independ: independent from, develop: media1 big toe well develop- ed, invers: inversion, no poly: no polydactyly

92 T. Miura et al.

For the third group, i.e., hallux varus caused by the anchoring of a dysplastic or degenerated medial great toe, resection of the anchoring substance and rotational skin flap from the interdigital space to the medial side is required (Fig. 9b). At the proximal end of the anchoring substance, which is considered to be a remnant of the metatarsus of the medial great toe, in some patients, cartilagi- nous joint formation is seen between the tarsal bones. The skin at the medial side of the great toe is usually insufficient, and so requires supplemental skin coverage by the technique of Z-plasty or rotational local skin flap. For this purpose, the skin at the widened interdigital space between the 1st and 2nd toes may be available for use by the local rotational flap method.

DISCUSSION

The clinical features of 18 patients diagnosed as preaxial polydactyly or hallux varus were studied. Among the patients showing inversion of the great toe, except the patients with metatarsus adductus reported by Thomson (1960), there are three types: simple inversion of only the medial great toe due to being pushed out by polydactyly, inversion due to deformity of the metatarsus, and true inversion due to anchoring substance from a hypoplastic or degenerative medial great toe.

These 3 groups present fairly different clinical symptoms, described below. In the case of hallux varus caused by an internal anchoring effect of a hypoplastic or degenerative medial great toe, Hass (1983), Farmer (1958), that of Kitayama et al. (1985) each described one patient, and Tokunaga (1983) reported 2 patients; each of these was affected only on oneside. Among the 18 patients reported in this paper, 3 patients showed this type of deformity, and all of them were unilaterally affected. On the other hand, hallux varus due to a deformed metatarsus was reported for 2 patients by Farmer (1985), 1 patient by Furuta et al. (1981), and 5 patients by the authors; all of these were bilaterally affected. Furthermore, in the cases caused by deformity of the metatarsus, a familial disposition was frequently found (inherited), while the families of patients with hallux varus due to anchoring substance revealed no polydactyly nor hallux varus (sporadic). Polydactyly of the hand is also found in the patients with a deformed metatarsus. The clinical features of cases of so-called hallux varus are thus completely different from each other (Table 1). Therefore, it is not adequate to treat them as the same disease under a simple diagnosis of hallux varus.

REFERENCES

Farmer, A.W. (1958) Congenital hallux varus. Am. J. Surg., 95: 274-278.

Furuta, K., Isida, F., Ueba, Y. and Akahori, 0. (1981) Polysyndactyly of bilateral hand and foot. Cent. Jpn. Orthop. Traumat. (Chubu Seisai), 24: 546- 549. (Japanese)

Haas, S.L. (1938) An operation for the correction of hallux varus. J. Bone Joint Surg., 20: 705-708.

Huurman, W.W. (1978) Congenital foot deformities. DuVries’ Surgery of the Foot, (Mann, R.A. ed.),

Mosby, Saint Louis, 94-95. Kitayama, Y., Kojima, M., Tsukada, S. and Wang, C.G.

(1985) Surgical treatment of polydactylia of the toes. Jpn. P.R.S., 5: 383-391. (Japanese)

Sloane, D. (1935) Congenital hallux varus; Operative correction. J. Bone Joint Surg., 17: 209-211.

Thomson, S.A. (1960) Hallux varus and metatarsus vows. Clin. Orthop., 16: 109-118.

Tokunaga, J. (1983) Congenital hallux varus. Orthop. Surg. (Seikeigeka), 34: 1189-1193. (Japanese)