0198-0211/92/1309-0536$03.00/0 FOOT & ANKLE Copyright © 1992 by the American Orthopaedic Foot and Ankle Society, Inc.

Metatarsal Lengthening by Distraction Osteogenesis: A Report of Two Cases Terence Saxby, M.D., and James A. Nunley, M.D. Durham, North Carolina

ABSTRACT

border of her foot associated with deviation of her lesser toes. Her pain was made worse by activity. On examination, she walked on the lateral border of her right foot; there was a callosity under the fifth metatarsal head. There was obvious shortening of the first ray. Plantar sensation was intact but the dorsal sensation was diminished. There was scarring on the medial border of her great toe. X-rays revealed that the distal end of the metatarsal was absent; the proximal and the distal phalanx were present, and the first ray was 2.8 cm short (Fig. 1A). She underwent a corticotomy and placement of a Kessler-metacarpal distractor. One week later she began slow distraction of 0.25 mm four times a day. Two weeks after the operation, the foot exhibited increased swelling and the skin on the dorsum of the foot was irritated by the external fixater. She returned 3 weeks after the operation with further skin irritation and actual skin breakdown. At this point, it was decided to exchange her Kessler device for a miniature Orthofix device (M-100). Once the orthofix distractor was applied, lengthening resumed; there were no further skin problems and, radiographically, she achieved 2.5 cm of lengthening. At this point, distraction was stopped, full weightbearing was instituted, and the fixater remained in situ until total radiographic consolidation of the new bone regenerate. At 10 weeks after the operation, her radiographs showed good bone regeneration (Fig. 1, B and C) and the device was removed. Sixteen weeks after the operation, her radiographs showed complete consolidation of regenerate (Fig. 10); at this time, she returned to work. On examination she had a normal gait and could tiptoe and heel walk. The total lengthening for this case was 2.5 cm. At 1-year follow-up, she was still asymptomatic despite the radiographic appearance of arthritis at the metatarsophalangeal joint.

Two cases of lengthening of metatarsals by distraction osteogenesis are reported. One of these cases is an acquired deformity of the first metatarsal; the other is a congenital short fourth metatarsal. By following the principles set forth by IIizarov, it was possible to lengthen the metatarsal bones and surrounding soft tissues without open lengthening of tendons or secondary bone grafting of the distraction gap. We believe this method is an improvement over previously described methods of metatarsal lengthening.

INTRODUCTION

Lengthening of an acquired deformity of a metatarsal by distraction osteogenesis has not been recorded previously; however, there are two case reports in foreign medical journalsv" about using this technique in congenital deformities. Both of these case reports are for congenital shortness of the lesser metatarsals. Here, we report on two cases of metatarsal lengthening by distraction osteogenesis. One case, similar to the above reports, was a congenital shortness of the fourth metatarsal; however, the other case was that of an acquired deformity of the first metatarsal. CASE HISTORY 1

A 22-year-old female presented with a history of sustaining an injury to her right first metatarsal at age 4 when a lawn mower ran over her foot and she suffered an open segmental fracture of her first metatarsal. Treatment involved irrigation and debridement with excision of bony fragments. The wound was eventually closed and she had an uneventful postoperative course, except she had marked shortening of her first ray. The patient presented 18 years later with increasing pain while walking, recurrent ankle sprains, an inability to wear high-heeled shoes, and a callosity on the lateral

CASE HISTORY 2

A 15-year-old girl with Turner's syndrome-Mosaic, presented complaining of pain in her right foot for the last several years. This pain was mechanical in nature

From the Department of Surgery, Division of Orthopaedics, Box 2919, Duke University Medical Center, Durham, North Carolina 27710. Address reprint requests to Dr. Nunley,

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Fig. 1 A, Standing preoperative radiograph demonstrating shortening of the first ray with incongruous metatarsophalangeal joint. B, AP radiograph 10 weeks after distraction osteogenesis demonstrating 2.5 cm of lengthening with good regenerate bone; the Orthofix device was in place. C, Lateral radiograph demonstrating position of pins in Orthofix lengthener. D, Standing radiograph 16 weeks after surgery demonstrating excel/ent restoration of length of first metatarsal; however, there was still an incongruous metatarsophalangeal joint.

and was worse with tennis and running. On examination of her right foot, there was obvious shortening of the fourth ray (Fig. 2A). The plantar aspect revealed that the fourth metatarsal head was well proximal to the normal cascade of the metatarsal heads and not functioning in its normal role of weightbearing. Radiographs confirmed the congenital shortening of the fourth metatarsal (Fig. 2B). She underwent lengthening of her fourth metatarsal with the use of a miniature Orthofix external fixator. The Orthofix was placed with two pins on each side of

the metatarsal and then the metatarsal was osteotornizeo. There was no soft tissue lengthening carried out. The patient was reviewed at 6 days after surgery and lengthening was begun at 0.25 mm four times a day (Fig. 2C); she was instructed to bear weight as tolerated. She was seen at 5 weeks after surgery and radiographs at this stage revealed good bone regenerate, and the metatarsal head had assumed its normal position in the metatarsal cascades. At this stage, lengthening was stopped; she remained in the external fixator for another month. At the 3-month follow-up,

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Fig. 2 A, Appearance of the right foot of a 15-year-old child with congenital shortness of the fourth metatarsal. B, Oblique radiograph demonstrating severe shortening of the fourth metatarsal with intact proxirnat phalanx and metatarsophalangeal joint. C, Lengthening in progress with Orthofix device and four pins in the fourth metatarsal. D, Standing AP radiograph after complete regeneration of 1.4 cm to fourth metatarsal. Note the nice arcade of the metatarsal heads. E, AP and F, oblique photographs 1 year after distraction lengthening of 1.4 cm to the fourth metatarsal. Photographs show the excellent cosmetic result.

the patient was able to walk without any limp. She was advised that she could resume normal activities. At 6month follow-up, the patient was back to her normal activities of running and playing tennis. There was normal range of movement of the metatarsophalangeal joint. Radiographs confirmed total consolidation of the regenerate. The total lengthening for this case was 1.4 cm (Fig. 2D). One year after surgery, the patient was quite pleased with the appearance of her foot (Fig. 2, E and F) and was able to participate in all activities without restriction or pain. DISCUSSION

The lengthening of bones is not new to orthopaedic surgery; Codivilla1 published the first report in 1905. Lengthening of a metatarsal is also well described.v"

However, it is the work of lIizarov2 - 4 that has greatly increased the understanding of the biology of the bone and soft tissue regeneration. lIizarov's principle of tension stress states that "living tissue when subjected to slow steady traction becomes metabolically activated by synthetic and proliferative pathways, a phenomenon dependent on vascularity and functional use."2 Both through extensive research and clinical observation, lIizarov has demonstrated the significance of the rate and rhythm of distraction and the importance of preservation of the soft tissue envelope and accompanying vascularity. He identified seven principles that are important in proper formation of new bone within the distraction gap: (1) maximum preservation of marrow and periosseous blood supply; (2) stable external skeletal fixation; (3) a latency before commencing distrac-

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Foot & AnklejVol. 13, No. 9/November/Oecember 1992

tion; (4) a distraction rate of 1 mm/day: (5) distraction in small frequent steps; (6) a period of neutral fixation after distraction; and (7) normal physiological use of the elongated limb. When undertaking the lengthening of these two cases, we attempted to follow as closely as possible these principles. However, because of the unique anatomies and the desire to lengthen only one metatarsal bone in each patient, modifications were necessary. These modifications included, first, an open osteotomy of the bone, whereas IIizarov recommends a percutaneous corticotomy. The reason for this was that we believed it was technically extremely difficult to perform a percutaneous corticotomy in a single metatarsal bone. However, when performing the open osteotomy, we were aware of the importance of the periosseous blood supply and tried to preserve this as much as possible. Our second deviation from IIizarov's principles was in the use of a noncircular external fixator. We thought it was technically impossible to apply a circular or semicircular frame to lengthen selectively one metatarsal. Therefore, we initially chose the Kessler device principally because of our previous experience with its use in the hand. However, because of its configuration, it led to skin problems with swelling in the foot. Therefore, we changed to what we felt was a more stable configuration: an Orthofix miniature external fixator; this device gave excellent rigidity. This seemed to fulfill IIizarov's recommendation for elimination of undesirable micromotion at the osteotomy site, yet permitted micromotion parallel to the bone axis.

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The other five principles were carried out without modification. These two cases demonstrate that it is possible to lengthen the metatarsals for acquired as well as congenital deformity by following IIizarov's principles. We believe this method to be an improvement over previous methods of bone lengthening, but the surgeon still must be cognizant of the indications for this type of surgery and must inform the patient of its advantages as well as its potential complications.

REFERENCES 1. Codivilla, A.: On the means of lengthening, in the lower limbs. the muscles and tissues which are shortened through deformity. Am. J. Orthop. Surg., 2:353-369,1905. 2. IIizarov, G.A.: The tension-stress effect on the genesis and growth of tissues. Part I: The influence of stability of fixation and soft-tissue preservation. Clin. Orthop., 238:249-281,1989. 3. IIizarov, G.A.: The tension-stress effect on the genesis and growth of tissues. Part II: The influence of the rate and frequency of distraction. Clin. Orthop., 239:263-285, 1989. 4. lIizarov, G.A.: Clinical application of the tension-stress effect for limb lengthening. Clin. Orthop., 250:8-26, 1990. 5. Nogarin, L., Magnan, B., Bragantini, A., and Molinaroli, F.: The surgical correction of metatarsal dysmetria. Ital. J. Orthop. Trauma, 14:77-80, 1988. 6. Urano, Y., and Kobayashi, A.: Bone-lengthening for shortness of the fourth toe. J. Bone Joint Surg., 60A:91-93. 1978. 7. Urbaniak, J.R., and Richardson, W.J.: Diaphyseal lengthening for shortness of the toe. Foot Ankle, 5:251-256.1985 8. Wakisaka, T., Yasui, N., Kojimoto, H., Takasu, M., and Shimomura, Y.: A case of short metatarsal bones lengthened by callus distraction. Acta Orthop. Scand., 59:194-196. 1988.

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Metatarsal lengthening by distraction osteogenesis: a report of two cases.

Two cases of lengthening of metatarsals by distraction osteogenesis are reported. One of these cases is an acquired deformity of the first metatarsal;...
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