SECTION II ORIGINAL ARTICLES: Pediatrics
Melorheostosis is a disease of bone and soft tissues characterized by hyperostosis along the cortex, mimicking candle drippings, and periosseous fibrosis of soft tissues. The soft tissue contracture and periarticular fibrotic changes of melorheostosis can result in limb shortening or lengthening, angular deformity, and joint contracture. 1,2,4,5,9,15 Joint restriction and contracture may result from associated muscular and skin involvement, characterized by atrophy and subcutaneous fibrosis, respectively. 1,8,15 The fibrotic tissue does not stretch with the growth of the limb, causing deformities to recur as a result of continued tethering. 2,3,15 Therefore, conservative methods typically are ineffective, yet recurrences are common after surgical treatments. 15 The Ilizarov technique has been suggested as an option for limb shortening and soft tissue and joint contractures. 1,3,6,7,11,12 To date, there only are two reports in the English language literature on the treatment of conditions associated with melorheostosis using the Ilizarov technique: one study reported on lengthening of the lower leg, 1 and the other study reported on correction of flexion contracture of the knee, followed by lengthening of the lower leg. 9 The current authors report a patient with recurrent equinoplanovalgus deformity of the foot caused by melorheostosis treated with the Ilizarov apparatus.
A 14-year-old boy presented with recurrent equinoplanovalgus deformity of the right foot and overriding of the fifth toe. When he was 4 years old, his parents observed that he had a slightly dorsiflexed fifth toe. When he was 6 years old, the foot gradually progressed to having an equinoplanovalgus deformity, and the patient finally was diagnosed with melorheostosis. When the patient was 8 years old, an orthopaedic surgeon attempted to correct the foot deformity using Ilizarov’s distraction treatment without osteotomy. This was followed by 4 weeks of external fixation. After this time, the patient wore a short leg cast for 3 weeks. The foot deformity recurred and progressively worsened with time.
On physical examination, severe equinoplanovalgus (40° equinus, 15° valgus) and forefoot abduction (30°) with the fifth toe dorsiflexed and adducted overriding on the fourth toe were seen. There was 10° flexion deformity of the right knee. The ankle motion was approximately 10°, but subtalar motion was negligible. The patient could not bear weight on the lateral border of the foot. The skin and subcutaneous tissue over the dorsolateral aspect of the midfoot and hindfoot, and the posterolateral aspect of the ankle behind the lateral malleolus, along a sclerodermal distribution, 14 were rubbery firm and tightly fixed to the underlying bone (Fig 1). Radiologic examination showed patchy periosteal and endosteal hyperostosis in the tarsal, metatarsal, and phalanges, which matched with the skin and subcutaneous lesions (Fig 2). Two- and three-dimensional computed tomography scans clearly showed the localization of the hyperostosis and the misshaped tarsal bones. Digital subtraction angiography showed mild hypovascularity, particularly in the lateral aspect of the foot.
During surgery, the Achilles tendon was lengthened by Z-plasty and the tendon of the extensor digitorum longus to fifth toe was divided at the metatarsophalangeal joint. Using a separate skin incision over the dorsolateral aspect of the hindfoot, the peroneus brevis tendon was cut at the insertion site. An incomplete calcaneal osteotomy was made approximately 1.5 cm proximal to the calcaneocuboid joint in the area between the anterior and middle facets, which corresponded to the junctional area between the hyperostotic bone and the normal cancellous bone in the distal calcaneus. Two, 5-mm half-pins were inserted in the distal calcaneus for later fixation to the ¼ ring.
The Ilizarov frame was applied from the lower leg to the foot. Two rings were fixed to the tibia only, using 1.8-mm transfixing wires and 5-mm half-pins. The foot assembly was composed of a ¼-ring to the distal calcaneus, and two additional half-rings to the proximal calcaneus and metatarsals, respectively. An outrigger, pulling the tip of the fifth toe downward and away from the fourth toe, was assembled into the forefoot half-ring. Two half-pins, previously inserted into the distal calcaneus, were fixed to the ¼-ring, which then was connected to the half-ring fixed to the metatarsals, and the calcaneal osteotomy was completed. The osteotomy site was fixed temporarily with a Kirschner wire, which was removed on postoperative Day 10 (Fig 3). Using this Ilizarov frame, gradual correction of the forefoot abduction, the midfoot planus, and the hindfoot equinovalgus deformities were done, starting from postoperative Day 5. Calcaneal lengthening also was done by distraction osteogenesis. The rate of distraction was adjusted depending on pain or discomfort. 3 All components of the deformity were corrected satisfactorily within 23 days, and the correction was stabilized for 8 additional weeks. At the time of Ilizarov frame removal, residual forefoot abduction was corrected by a closing wedge osteotomy of the medial cuneiform, and the residual knee flexion deformity was corrected using the Strayer operation. 13 The patient wore a long leg cast for 4 additional weeks. Postoperatively, the patient could walk with a plantigrade foot, without using an orthosis.
Recent clinical and radiologic examinations at age 18 years revealed that the patient had a normal gait with a plantigrade, painless, functional right foot with a good appearance. He could participate in sports activities. He had a reasonably good range of ankle motion (10° dorsiflexion and 40° plantar flexion), although subtalar motion was limited to 10° inversion and 10° eversion. Range of motion in the fifth metatarsophalangeal and interphalangeal joints decreased moderately. There was no flexion deformity of the right knee.
The Ilizarov method has many advantages in the treatment of complex foot deformities, particularly those with severe scarring and poor vascularity. 1,3,6,7,11 It requires only minimal dissection and therefore, decreases the risk of neurovascular and soft tissue injury. When necessary, correction also can be done at either the bone or the joint, or by arthrodesis, depending on the severity and dimension of the deformities. 6,11 Because the Ilizarov method relies on osseous and extraosseous neohistogenesis, severe deformity also can be corrected by lengthening the osseous and nonosseous tissues, thereby alleviating the need to shorten the foot by bone resection. For correction of hindfoot valgus and midfoot planus, the authors adopted a technique of calcaneal lengthening 4 using distraction osteogenesis. When the relative longitudinal length of the lateral column to that of the medial column was normalized, valgus deformity was corrected and the longitudinal arch was restored. 10
Marshall and Bradish 9 reported that the regenerated bone after distraction osteogenesis in the middle of the hyperostosis region had the radiologic appearance of the original bone, suggesting that the underlying disease was a disorder of intramembranous ossification. In the current case, the authors observed that the radiologic appearance of the regenerated bone appeared to be a mixture of normal cancellous bone and patchy hyperostosis, whereas the radiologic density of the original area of dense hyperostosis decreased to some degree (Fig 4).
To the best of the current authors’ knowledge, this is the first report on the Ilizarov technique for complex foot deformity caused by melorheostosis. The equinoplanovalgus deformity in the current patient was very recalcitrant. A previous surgical attempt, which repositioned the foot after simple soft tissue stretching using the Ilizarov method, was not effective in preventing recurrence, presumably because of a recoil phenomenon of the thick fibrous tissue. Surgical and gradual correction of the soft tissue and osseous components by the Ilizarov method provided an excellent and persistent result in a recurrent equinoplanovalgus deformity caused by melorheostosis.
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