A rare polydactyly of the forefoot with partial duplication of the 5th metatarsal and supernumerary digit: A case report

Abstract

Introduction

Polydactyly of the foot is a congenital anomaly characterized by the appearance of all or part of one or more additional rays. Adult cases are more rare, and surgical management of the deformity is still debated.

Presentation of case

A 49-year-old black patient with this condition might complain of an abnormal cosmetic appearance or difficulty with footwear.

Discussion

Only a few cases of postaxial polydactyly with a partial duplication of the fifth metatarsal without a supernumerary digit have been reported.

Conclusion

The surgical indication is always retained in front of the aesthetic discomfort of the patient associated with footwear. The surgical technique must be individualized according to the deformity encountered, either by open or percutaneous approach; we find it interesting to share this unusual case in order to classify it later as a foot deformity.

Highlights

• •Particular anomaly not described in the literature.
• •Polydactyly of the forefoot with partial duplication of the 5th metatarsal and supernumerary digit.
• •Surgical procedure of this rare condition is still a matter of debate.

1. Introduction

Postaxial polydactyly of the foot is one of the most common congenital malformations. Only a few cases of postaxial polydactyly with a partial duplication of the fifth metatarsal without a supernumerary digit have been reported, and both metatarsal heads were united to form a common joint with the proximal phalanx in all of those cases. No sex predilection has been identified, but geographical incidence variations have been reported: Whites have an incidence of 0.3–1.3 cases per 1000 live births and blacks have an incidence of 3.6–13.9 cases per 1000 live births. We encountered an exceedingly rare presentation of foot postaxial polydactyly that, to our inspection, had neither been previously classified nor described in published studies. We present a rare case of postaxial polydactyly with a partial duplication of the fifth metatarsal characterized by dual metatarsal heads with a supernumerary digit. We propose that this heretofore unmentioned presentation of postaxial polydactyly be added to the existing systems of classification of polydactyly.

This work has been reported in line with the SCARE criteria [1].

2. Case report

A 49-year-old patient who consulted for a malformation syndrome of the 5th ray (Fig. 1); the patient felt uncomfortable wearing footwear and was willing to have surgery; the intervention was explained to the patient, it consisted of the resection of the supernumerary bone, osteotomy of the 5th metatarsal and arthrodesis of the MTP of the 5th ray.

Fig. 1.

: Clinical photograph of the patient's right foot.

The x-ray of the foot showed a bifid metatarsus with duplication of the proximal phalanx (Fig. 2, Fig. 3).

Fig. 2.

Dorsoplantar weightbearing (A) and oblique (B) radiographs of the right foot.

Fig. 3.

intraoperative image of the osteotomy site.

The surgical procedure: The approach began by locating the 5th metatarsal, an incision was made in opposite of the diaphysis as it's consisted of an osteotomy at the M5 neck for the supernumerary radius, freshening of the articular surfaces of the metatarsophalangeal and arthrodesis with a screw; gentle compressive postoperative bandaging was then used to splint the digits in an effort to prevent the development of angular deformities and to encourage normal forefoot contouring. The initial postoperative management entailed immediate weight bearing as tolerated in a surgical shoe.

The evolution in the first month was marked by clean healing of the wound, a straightening of the axis of the 5th ray (Fig. 4, Fig. 5).

Fig. 4.

Postoperative dorsoplantar nonweightbearing radiograph of the right foot.

Fig. 5.

Clinical photographs of the illustrated case at week 6 after the operation showed good correction of the splay forefoot and dorsiflexed fifth metatarsal.

3. Discussion

In the literature, we found four cases of postaxial polydactyly with a partial duplication of the fifth metatarsal, and they could not be classified based on previous classification systems [2]. Thus, we directly categorized them into three types as follows. First, the fifth metatarsal was partially duplicated without a supernumerary digit, and both metatarsals were conjoined at their heads [3]. Second, the malformation was the same as the first type except with an extra hypoplastic proximal phalanx in the lateral side of the fifth proximal phalanx [4]. Third, the fifth metatarsal was partially duplicated, with dual metatarsal heads and a supernumerary digit, and an extra digit was fused at the base of the proximal phalanx [5].

Summary of the cases discussed.

Postaxial polydactyly with a partial duplication of the fifth metatarsal
Without a supernumerary digit conjoined heads	With an extra hypoplastic proximal phalanx in the lateral side	With a supernumerary digit an extra digit was fused at the base of the proximal phalanx

In the current patient, the fifth metatarsal was partially duplicated, with dual metatarsal heads, and there was supernumerary digit; nevertheless, this malformation is different from the three types described previously.

Postaxial polydactyly with a duplicated metatarsal is manifested with or without a supernumerary digit [2].

Blauth and Olason classified the malformation longitudinally according to the level at which the bifurcation begins [6].

Supernumerary digits have all the digital components distal to the splitting level because limb malformation occurs in a proximal to distal order in the early stages of development [7].

Ishii et al. [8] reported two cases of complete polymetatarsia without a supernumerary digit and suggested that one possible explanation for the etiology of polymetatarsia without a supernumerary digit is contiguity fusion of the overinduced phalanges after the induction of excess digital rays. Hayashi et al. [3] also reported a case of postaxial polydactyly with a duplicated metatarsal with normal phalanges and concluded that two embryologic failures seemed to have been involved in causing their anomaly.

In the case of polydactyly of the fifth ray of the foot, some investigators have suggested that the most lateral digit should be excised, irrespective of whether this is the more fully formed digit [9]. In contrast, Kojima et al. [10] recommended fifth toe excision because sixth toe excision carried a greater risk of circulatory compromise when the fourth interdigital space is separated. Phelps and Grogan [11] also advocated excision of the medial toe and metatarsal in the phalangeal type of polydactyly, in which the alignment of the phalangeal bone is abnormal and the associated tendon structures hypoplastic.

Recently, a number of investigators have emphasized individualization of the surgical approach.

[12] and excision of the most hypoplastic element is generally considered favorable regardless of its transverse position [13]. Although this approach to polydactyly involves more complex surgery than straightforward excision of the lateral element, we believe that it yields a superior cosmetic and functional result [14], and cosmetic is an important element of patient satisfaction in many cases of polydactyly of the foot.

We believe that the percutaneous method of excision of the more medial ray described in a previous report, could be useful on a wider scale. Classically, an open correction of the metatarsal type of polydactyly is undertaken, although this results in the formation of a long dorsal surgical scar on the involved foot [6]. We believe that the percutaneous approach to supernumerary ray amputation can be useful, particularly in the hands of a surgeon well versed in minimally invasive surgical techniques; and it is important for surgeons to master traditional open techniques before undertaking the percutaneous procedure [6].

4. Conclusion

Postaxial polydactyly with partial duplication of the fifth metatarsal is manifested in various forms with or without supernumerary toe, the surgical indication is always retained in front of the aesthetic discomfort/pain of the patient associated with footwear. The surgical technique must be individualized according to the deformity encountered, either by open or percutaneous approach.

Consent

The patient gave written permission to publish his case.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Ethical approval

The ethical approval has been exempted by our institution sources of funding: hospital management.

Author contribution

Karim Chafai El Alaoui, Amine El Yazidi Wrote The Article, Hatim Abid, Mohammed El Idrissi et Abdelmajid El Mrini Critical Lecture and Final Approval. All authors read and approved the final version of the manuscript.

Guarantor

Karim Chafai El Alaoui, Amine El Yazidi

Research registration number

None.

Conflict of interest statement

None.