Apert syndrome

Received 7 August 2002; Accepted after revision 7 February 2003

We treated 35 brachymetatarsal rays of 18 feet in 12 patients by one-stage lengthening with interpositional bone grafts or by gradual lengthening with callotasis combined with shortening of the adjacent metatarsals and phalanges. Definition of the two parabolas which connect the metatarsal heads and the tips of the toes, and recognition of three patterns of metatarsal length, were helpful guides in treatment. In total, 36 excisions of the phalanges and/or the metatarsals were undertaken. The mean shortening was 8 mm.

The radiological results were satisfactory. The mean values were as follows: one-stage lengthening, length gain, 1.3 cm; healing index, 1.3 months/cm; percentage increase, 30%; gradual lengthening, length gain, 2.0 cm; healing index, 2.0 months/cm; percentage increase, 50%.

Associated shortening of an adjacent bone can avoid the disadvantages of one-stage lengthening which may not achieve target length and can result in neurovascular complications. Reduction of the target length enables the surgeon to carry out one-stage instead of gradual lengthening. It also shortens the length of treatment in the group undergoing callotasis and improves cosmesis.

Brachymetatarsia is diagnosed when one metatarsal ends 5 mm or more proximal to the parabolic arc.1 It usually occurs in a single metatarsal, and the fourth ray is most frequently affected. The causes of brachymetatarsia may be congenital, post-traumatic, postsurgical, or linked to specific disease processes such as Down's syndrome, Apert's syndrome, Albright's osteodystrophy, sickle-cell anaemia, diastrophic dwarfism, and poliomyelitis.1-3 Brachymetapody, when there are multiple abnormally short metatarsals, is a serious cosmetic problem.1,4

Despite potential complications, the surgical correction of brachymetatarsia tends to favour lengthening procedures. One-stage lengthening with an interpositional bone graft and gradual lengthening by callotasis are the two techniques most widely used.1,2,5-8 In evaluating a patient with brachymetatarsia, numerous variables must be assessed, including the number of rays affected, the amount of lengthening required, the method of lengthening, the possibility of combined adjacent shortening, the sources of bone grafts, the options for internal and external fixation, soft-tissue contracture, and the tension of the skin.

Our aim was to evaluate the feasibility of combined lengthening and shortening of adjacent metatarsal and phalangeal bone using the parabola formed by the tips of the toes (Fig. 1) and three metatarsal types (Fig. 2) as guides.9

Patients and Methods

We studied 35 examples of brachymetatarsia in 18 feet (12 patients) which we had treated by either one-stage lengthening with an interpositional bone graft (five patients with a unilateral fourth ray and one with unilateral fourth and fifth ray brachymetatarsia), or gradual lengthening by callotasis (five patients with bilateral first and fourth ray brachymetatarsia). The study also included one patient with first, third, fourth, and fifth metatarsal involvement on both feet treated by second metatarsal and proximal phalangeal shortening. All patients were treated by combined adjacent metatarsal or phalangeal shortening (Table I). Because of the relatively young age of the patients in our study, the primary reason for surgical correction was cosmetic rather than functional. Before operation, four patients complained of problems with hygiene in the area of the recessed fourth web. One had a plantar keratosis beneath the fourth toe which gave mild discomfort, but her major concern was cosmetic. In one patient the problem was caused by injury, 11 had congenital conditions. There were nine females and three males. The mean period of follow-up was three years. The clinical results were assessed as follows: excellent (improved cosmetic and functional results), good (improved cosmetic and unchanged functional results), and fair (improved cosmetic but poor functional results). Difficulty in walking on tiptoe or any limitation of daily activities was assessed as poor function.

Preoperative plan for bone shortening. We used an antero-posterior (AP) radiograph to determine the site for bone shortening after analysis of the relationship of the metatarsals and phalanges based on the curves of the two parabolas (Fig. 1). The toe-tip parabola is important for cosmetic improvement and the metatarsal head parabola for functional improvement. The metatarsal head has an important weight-bearing function during walking, especially at toe off. The three metatarsal types in a normal foot must be considered in the preoperative plan according to their length (Fig. 2).9

The basic concept of a preoperative plan for the bone shortening procedure is summarised in Table II. For example (Fig. 2), in first-ray brachymetatarsia, second and third metatarsal or proximal phalangeal shortening can reduce the target length and the percentage increase of the first metatarsal to 40% or less. Postoperatively, the metatarsal type B is preferable to type A or type C in order to reduce complications associated with excessive bone lengthening. In a fourth-ray brachymetatarsia, shortening the second and third metatarsals is possible in both metatarsal types A and B, thereby changing them into metatarsal type C after operation. In preoperative metatarsal type C, one-stage or gradual lengthening can be carried out without adjacent bone shortening because of the relationship of the short second metatarsal to the first in this type. In combined first- and fourth-ray brachymetatarsias, shortening of the second and third metatarsal or the proximal phalanx can reduce the amount of the target length and the percentage increase.

The same concept can be applied to bone shortening in other forms of brachymetatarsia. In a patient with a single long metatarsal and phalanx (case 12), shortening can be undertaken in both the metatarsal and the proximal phalanx. In certain patients with a single long metatarsal and a concomitant short proximal phalanx, adjacent phalangeal shortening will be required after metatarsal shortening to establish a smooth parabola of the tips of the toes.

Methods of lengthening. In the one-stage lengthening procedure, the osteotomies were gradually distracted with a small bone spreader while the ray was fixed with an intramedullary Kirschner wire (0.16 cm) to decrease surrounding soft-tissue tension. After achieving a satisfactory metatarsal parabola, one or two temporary transverse Kirschner wires were passed through the distal portion of the distracted metatarsal to the adjacent metatarsals. They stabilised the space for the bone graft and plate fixation. In gradual lengthening by callotasis, all patients had lengthening of the extensor tendon by Z-plasty. Two distal and proximal mini-half pins were inserted into the distal and proximal metaphysis, the cuneiform, or the cuboid. Distraction proceeded at the usual rate of 0.5 or 0.75 mm/day in two or three steps after seven to ten days.

We undertook gradual lengthening in all first-ray brachymetatarsias. In other rays, the selection of the method of lengthening was based on a target length determined by tracing an AP radiograph of the foot and carrying out the several possible adjacent bone-shortening procedures on this model (Table II). We performed a one-stage lengthening with an interpositional bone graft in a patient with fourth brachymetatarsia when the target length after adjacent bone shortening was less than 15 mm. We used resected bone from the adjacent metatarsal, the proximal phalanx, or bicortical iliac bone for a bone graft in the acutely distracted gap in the middle of the metatarsal. Gradual lengthening by callotasis was chosen for patients in whom the target length, even after adjacent bone shortening, was 15 mm or more.

Other procedures. The superfluous skin after phalangeal shortening can be remodelled without cosmetic complications. A wedge-shaped triangular excision at the level of the interdigital web area can provide cosmetic improvement.

Fixation of the site for bone shortening or lengthening can be achieved by a looped wire, intramedullary Kirschner wire or crossed Kirschner wires, or a small plate. We prefer the small plate because it provides greater immobility and lessens the chance of articular damage which can occur when using an intramedullary Kirschner wire.

A plantar flexion deformity of the toe may be encountered in the lengthening procedure. It can be corrected during the primary operation after fixation of the site of lengthening in the one-stage procedure (Fig. 3), or as a secondary operation in gradual lengthening. Lengthening of the long flexor by Z-plasty can be undertaken in the metatarsophalangeal joint area. The short flexor can be tenotomised or lengthened. To lengthen the short flexor, one of the slips is cut distally and the other proximally near the site of separation of the tendon. Suturing the long distal stump of one side to the long proximal slip of the other side lengthens it. Preservation of the flexor pulley and suture of the tendons with adequate tension for flexion and extension gives a natural posture of the toe. A thickened plantar capsule of the metatarsophalangeal joint is often a major cause of limited dorsiflexion of the toe and a plantar capsulotomy may be required.

Results

We analysed the results using the gain in length, the target length, the healing index, the percentage increase, the amount of bone shortening and the expected decrease in the period of treatment in the callotasis group, and the complications. Bone shortening was carried out at 36 levels (9 metatarsal and 27 proximal phalanges) (Table I). The mean amount of bone shortening was 8 mm in both the one-stage lengthening (Fig. 4) and the callotasis groups. The mean gain in length was 13 mm in the one-stage lengthening group and 20 mm in the callotasis group, with their target lengths before adjacent bone shortening being 21 mm and 28 mm, using the toe-tip parabola and 19 mm and 25 mm, using the metatarsal-head parabola, respectively. The corresponding mean percentage increase was 30% and 50% in each group. The mean healing index was 1.3 months/cm from identification of bridging callus at the bone graft site in the one-stage lengthening group and 2.0 months/cm in the callotasis group. When considering the amount of bone resection (mean 8 mm) and healing index (mean 2.0 months/cm), the expected decrease in the period of treatment for the callotasis group was almost 1.6 months.

The clinical results were satisfactory. Of the 18 feet, ten had excellent and six good results. Two had fair results with stiffness of the metatarsophalangeal joint of the great toe and hallux valgus as complications, which the patients accepted because of the cosmetic improvement. The percentage increased length in these two feet (cases 8 and 9) was 60% and 70%, respectively, while the mean percentage increase in the callotasis group in the first ray was 50%.

Complications included erosion of the cartilage of the metatarsal head after temporary intramedullary fixation by Kirschner wires, a pseudarthrosis treated by secondary bone grafting in one-stage lengthening and fracture of the callus at a site of gradual lengthening which was treated by immobilisation.

Discussion

The major disadvantages of the two methods of lengthening of brachymetatarsia are well recognised. In one-stage lengthening with the interpositional bone graft technique, the undercorrection associated with neurovascular compromise and soft-tissue tension are common obstacles to satisfactory results.5 In gradual lengthening by callotasis, the attachment of an external fixator on the foot for an extended period is very uncomfortable for young children and adolescents. In bilateral cases with brachymetapody, the correction of all deformities requires fortitude from both the physician and the patient.

As our experience of patients with brachymetatarsia increased over the last ten years, we encountered many difficulties in treatment. These were mainly related to excessively short metatarsals and phalanges. Failure to achieve target length, as well as neurovascular problems in one-stage lengthening and insufficient formation of callus and axial deviation during gradual lengthening, led us to combine adjacent metatarsal and/or phalangeal shortening. This technique minimised the amount of lengthening required of the affected metatarsal.

For bone-shortening, it is important to consider the length ratios of the adjacent metatarsal and phalanx. In a normal foot, there are three metatarsal types according to their lengths.9 From our unpublished data with regard to the frequency of the three metatarsal types in 350 random subjects, the most frequent was the index minus type (62%), followed by the index plus-minus type (35%) and index plus type (3%). The mean length ratios of the first and fourth metatarsals were 0.9 and 1.0, respectively, in normal people (Fig. 5). The mean length ratios of the proximal phalanx in the same first and fourth rays were 1.0 and 0.9, respectively. In the foot with brachymetatarsia, which involved the first and/or fourth rays in our study, the mean length ratio of the first and fourth metatarsals was 0.7 and 0.8, respectively. In addition, the same mean length ratios of the proximal phalanx were 0.8 in the first ray and 0.7 in the fourth ray. These data suggested that excessive lengthening of the affected metatarsal beyond the normal parabolic alignment may often be required in the treatment of the brachymetatarsia to compensate for the shortness of the proximal phalanx if shortening of the adjacent bone had not been undertaken. A painful callosity may also have resulted under the head of the overlengthened metatarsal.

In five years, 35 cases of brachymetatarsia in 12 patients were treated with a combined adjacent metatarsal or phalangeal bone shortening to reduce the associated complications and the period of treatment. One-stage lengthening was carried out in the postaxial rays in which the target length was less than 15 mm. A gradual soft-tissue distraction technique, using a bone spreader, could help to avoid critical neurovascular compromise.6 Soft-tissue distraction of 15 mm or more was not easy, even with soft-tissue release and using an intramedullary Kirschner wire.6,10,11 It caused complications during distraction because of bending of the Kirschner wire or fracture of the osteotomised bone end as a result of excessive pressure of the spreader. In gradual lengthening by callotasis, our clinical experience supported other authors' results regarding joint stiffness or subluxation of the metatarsophalangeal joint, flexion deformity of the digit, and hallux valgus, which can occur when the increase in length is more than 40%.12,13 These complications were encountered even when using a soft-tissue release and/or fixation by Kirschner wires through the metatarsophalangeal joint during distraction.

In our study (Table II), the percentage increase of 40% is a reliable guide to avoid complications such as metatarsophalangeal joint stiffness in first-ray brachymetatarsia. The tendency for joint stiffness was evident around the percentage increase of 50%. Hallux valgus occurred in patients with an increase of more than 50%. In other rays, the use of target length, before and after adjacent bone shortening, was a convenient guide for evaluating the need for shortening and the amount required, as well as in deciding which method of lengthening should be applied. A target length of more than 15 mm may require adjacent bone shortening. One-stage lengthening could be undertaken safely when the target length was less than 15 mm. Gradual lengthening by callotasis was required when the target length was 15 mm or more, even after shortening of bone.

We recommend shortening of an adjacent bone in the treatment of brachymetatarsia in order to reduce the period of treatment and to avoid complications. The amount of lengthening should be limited to less than 50%, preferably 40%, of the original length of the bone in any digit, especially the first because of its functional importance. We believe that less lengthening provides a better functional outcome.

No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

References

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9. Lauf E, Weinraub GM. Asymmetric "V" osteotomy: a predictable surgical approach for chronic central metatarsalgia. J Fool Ankle Surg 1996;35:550-9.

10. Choi IH, Chung MS, Baek GH, Cho TJ, Chung CY Metatarsal lengthening in congenital brachymetatarsia: one-stage lengthening versus lengthening by callotasis. J Pediatr Orthop 1999;19:660-4.

11. Magnan B, Bragantini A, Regis D, Bartolozzi P. Metatarsal lengthening by callotasis during growth phase. J Bone Joint Surg [Br] 1995;77-B:602-7.

12. Masada K, Fujita S, Fuji T, Ohno H. Complications following metatarsal lengthening by callus distraction for brachymetatarsia. J Pediatr Orthop 1999;19:394-7.

13. Takakura Y, Tanaka T, Fujii T, Tamai S. Lengthening of short great toes by callus distraction. J Bone Joint Surg [Br] 1997;79-B:955-8.

H. T. Kim, S. H. Lee, C. I. Yoo, J. H. Kang, J. T. Suh

From Pusan National University Hospital, Pusan, Korea

H. T. Kim, MD, Associate Professor

S. H. Lee, MD, Resident

C. I. Yoo, MD, Professor

J. H. Kang, MD, Resident

J. T. Suh, MD, Professor

Paediatric Orthopaedic Unit, Department of Orthopaedic Surgery, Pusan National University Hospital, 1Ga-10, Ami-Dong, Seo-Gu, Pusan, Korea 602-739.

Correspondence should be sent to Dr H. T. Kim.

(C)2003 British Editorial Society of Bone and Joint Surgery

doi:10.1302/0301-620X.85B5.13733 $2.00

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