Equinocavovarus deformity of the foot is often seen in patients who have congenital clubfoot, myelodysplasia, poliomyelitis, Friedreich ataxia, Charcot-Marie-Tooth disease, or peripheral-nerve dysfunction following traumatic ischemia of the lower extremity. The operative methods that have been used to correct this deformity in adults include wedge resection of the midfoot, triple arthrodesis, excision of the talus, and osteotomy of different parts of the foot. Unsatisfactory results have been reported in the Russian literature, with persistent deformity and pain leading to impaired function. Operative intervention for severe deformity is often hazardous and fraught with complications because of the presence of insensitive skin, infection, and extremely thin and scarred skin as a result of previous operations. Furthermore, the large size of the wedge of bone that must be removed to achieve correction often results in a grossly shortened foot.
The Ilizarov compression-distraction apparatus has been used with and without an open procedure in children to correct equinocavovarus and other deformities of the foot1,3-7,10-12. In adults, the Ilizarov device generally has been employed as an adjunct to operative correction9,14, and we know of only one report that recommended the use of this device in adults without an associated open procedure2.
In 1972, Volkov, Oganesyan, and Povarov devised a hinged distraction apparatus to correct deformity of the foot without an open procedure8,13. The apparatus corrects the deformity by slow and gradual distraction of the capsules and ligaments of the joints of the foot. Once the desired correction has been obtained, the position is maintained for an additional period of time in the device, followed by immobilization in a plaster cast for a specified period and the use of corrective shoes. We report the results after this apparatus was used, with no associated open procedure, in adults to correct equinocavovarus deformity of the foot secondary to a variety of etiologies.
*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. No funds were received in support of this study.
†N. N. Priorov Central Institute of Traumatology and Orthopaedics, Moscow, Russia.
Sixty-five patients (eighty-three feet), who were an average of twenty-six years old (range, sixteen to fifty-six years old), were treated for equinocavovarus deformity of the foot (Table I). Forty-seven patients had a unilateral deformity, and eighteen had bilateral deformity. In twenty-two patients (twenty-two feet), the deformity had developed as a result of neurovascular injury of the extremity following severe trauma. Fourteen patients (fourteen feet) had residual paralysis after poliomyelitis, twelve (twenty-two feet) had Charcot-Marie-Tooth disease, eight (twelve feet) had clubfoot, four (five feet) had myelodysplasia, three (four feet) had cerebral palsy, one (two feet) had spondyloepiphyseal dysplasia, and one (two feet) had myopathy. The average duration of follow-up was ten years (range, three to nineteen years).
The patients had a variety of occupations, and all of them had continued to work for as long as they could despite the pain and deformity; twelve had become confined to bed or the house before they were seen by us. Thirty-four patients had neurotrophic changes on the feet, severe scarring, callosities, fragile skin cover, ulceration of the plantar surface of the foot, osteomyelitis of various bones of the foot, or a combination of these problems. When there was active ulceration, these patients would refrain from standing and walking as much as possible.
Thirty of the patients had had an operative procedure before they were evaluated at our hospital. These operative procedures included various types of arthrodesis of the midfoot and hindfoot, tenotomy and lengthening of various tendons, and corrective osteotomy. Fifteen of these patients had had an operation on the feet only, and fifteen had had additional operations on the proximal part of the lower extremity.
The functional status of the patient was assessed carefully before the device was applied. Most of the patients wore orthopaedic shoes; the patients who wore ordinary shoes found that the shape of the shoe soon conformed to the deformity of the foot. For all patients, anteroposterior and lateral roentgenograms of the foot and ankle were made before treatment, while the apparatus was in place, after the apparatus was removed, and at the time of the most recent follow-up evaluation. In addition, the patients were evaluated to exclude any who had psychological or psychiatric problems that could affect their compliance with the treatment protocol.
The indication for the procedure was severe equinocavovarus deformity of the foot, with or without neurotrophic changes, for which a corrective osteotomy would entail the removal of such a large wedge of bone that the foot would no longer be functional. The procedure was indicated even if there was a history of recurrent infection secondary to osteomyelitis.
Application of the Apparatus
The separate components of the apparatus were assembled the day before the operation; the process takes about one hour. The procedure of fitting the apparatus to the foot was done with the patient under general anesthesia and lasted about forty-five minutes. Antibiotics were given prophylactically only to patients who had a history of infection.
The apparatus consists of several hinged distractors and intermediary pieces that are used to change the position of the distractor bars in two planes perpendicular to each other. The use of hinges permits the application of forces in several planes, increasing the usefulness of the device.
An axial pin passes through the talus and is fixed to the axial stirrup. Another pin passes through the distal end of the metatarsals and is fixed to the distal stirrup, a third pin passes through the heel, and two pins pass through the middle third of the tibia and are fixed in the proximal and turning stirrups (Fig. 1).
The axial and turning stirrups are joined by the hinged distractors. The axial and distal stirrups are linked by side distractors that consist of two bars with intermediary devices. This allows the bars to be moved in perpendicular planes reciprocal to one another. The proximal and distal stirrups are connected to each other by the flexion-extension device in the middle (Fig. 1).
The hinged distractors are used to correct the varus deformity (Fig. 2, a) and the adduction deformity (Fig. 2, b), the side distractors that connect the axial and distal stirrups are used to correct the cavus deformity (Fig. 2, c), and the flexion-extension bar is used to correct the equinus deformity (Fig. 2, d).
No open procedure was performed, and correction of the deformity began five to seven days after the device had been applied. All elements of the deformity were corrected simultaneously at the rate of one millimeter each day (one complete turn of the six-sided nut), which was achieved by three or four partial turns of the nut during one twenty-four-hour period. Patients were discharged from the hospital if they were able to manipulate the apparatus; otherwise, they remained in the hospital for the entire period of distraction and stabilization. The severity and rigidity of the deformity, as well as the tolerance and cooperation of the patient, determined the length of time that was necessary to correct the deformity. The degree of correction was monitored with the help of roentgenograms, and the feet were overcorrected to compensate for the 10 to 15 degrees of correction that is lost after the apparatus is removed.
Diminished or absent motion of forty-three ankles (five of which had already had pantalar arthrodesis) was treated by using the hinged distraction apparatus as a compression device to achieve fusion without an open procedure. The articular surfaces were brought together at the rate of one millimeter each day. Forty ankles had a range of motion, and this was maintained with use of a bivalved cast on the foot and range-of-motion exercises of the ankle after the apparatus was removed.
The apparatus usually was kept in place for an additional two months after the desired position of correction had been achieved. Then, the patient wore a plaster cast for an average of two months and was allowed to begin bearing weight on the involved extremity. Custom-molded shoe-inserts were worn for at least one year.
The results were graded as good, satisfactory, or unsatisfactory. The result was considered good when all elements of the deformity had been corrected, the foot was plantigrade, there was an improvement in gait and the distance that the patient could walk, and the patient could wear ordinary shoes and return to work that involved walking and standing. The result was considered satisfactory when the deformity had not been completely corrected but the patient was able to walk and return to work wearing orthopaedic shoes and corrective shoe-inserts. The result was considered unsatisfactory when the deformity had recurred and the patient could not bear weight on the involved foot or feet even with orthopaedic shoes and corrective shoe-inserts.
Fifty-nine of the eighty-three feet had a good result in that all elements of the deformity had been corrected, full weight-bearing was possible, and gait had improved. Twenty feet had a mild residual deformity but were functional, so the result was considered satisfactory. The result in the remaining four feet initially was unsatisfactory because the deformity had persisted and the weight-bearing status had not improved (Table I). These four feet were in three patients who had Charcot-Marie-Tooth disease (Cases 13, 15, and 17), and the result may have been related to the progressive nature of the disease. An arthrodesis was subsequently done on these four feet, with a good functional result. The distraction apparatus may have been of some use, as minimum resection was needed to achieve correction. One patient (Case 44) could not tolerate the device, and an arthrodesis was done, with a satisfactory functional result.
Motion of forty ankles was maintained, and a fibrous fusion was produced by compression of the articular surfaces in thirty-eight ankles. All of the patients were able to return to their previous employment; however, at the time of the most recent follow-up evaluation, nineteen patients needed some assistance for self-care and basic homemaking needs, as a result of the primary disease.
Complications
Eight patients had inflammation of pin tracks, which may have been due to motion at the entry sites or to soft-tissue trauma. Antibiotics were injected locally into the soft tissues, and bandages soaked in antibiotics were applied around the pin sites. The pins were removed from five of the eight patients, and the apparatus was removed from three additional patients because of osteomyelitis; one of them had had chronic osteomyelitis of the tibia before the apparatus was applied (Table I).
Illustrative Case Reports
CASE 8. A seventeen-year-old girl had severe uncorrected bilateral clubfoot (Figs. 3-A, 3-D, and 3-E). The deformities were corrected in two stages (in 1980 and 1983), each of which lasted seven to eight months (Fig. 3-B). Six months after treatment, the feet were well corrected (Figs. 3-C and 3-F).
CASE 25. Bilateral equinocavovarus deformity developed secondary to a non-progressive myopathy in a twenty-three-year-old woman (Figs. 4-A, 4-B, and 4-F). The distractor was applied to both feet, and correction was achieved over eight weeks. The distractor was used for another eight weeks to maintain motion of the ankles and to stabilize the corrections (Fig. 4-C). Each apparatus was removed, and plaster casts were worn for an additional eight weeks. The patient wore shoe-inserts for one year. At the time of the two-year follow-up evaluation, she was able to bear full weight and had approximately 20 to 30 degrees of flexion and extension of the ankles (Figs. 4-D, 4-E, 4-G).
CASE 45. In 1979, a nineteen-year-old man sustained open fractures of the proximal part of the left tibia and fibula and the left foot, with injury of the peroneal nerve. Osteomyelitis of the tibia and fibula developed, and there was a residual equinocavovarus deformity (Figs. 5-A, 5-B, and 5-F). In 1981, the hinged distractor was used over a period of ten weeks to correct the deformity (Fig. 5-C). Compression of the ankle was maintained for four weeks, and the correction was stabilized for eight weeks with the apparatus attached to an orthosis. The patient then wore a plaster cast for eight weeks. After treatment, the foot was plantigrade in the neutral position (Figs. 5-D, 5-E, and 5-G).
Talyshinskii et al. suggested that poor results after the use of an external fixation device are related to incorrect operative technique, limited motion of the ankle joint, severe deformity of the foot, and muscular weakness. Disastrous complications can be associated with operative correction of severe equinocavovarus deformity in a patient who has neurotrophic changes in the foot, and amputation may become necessary. The use of external fixation has permitted the correction of these deformities without extensive resection of bone or internal fixation. The Ilizarov compression-distraction apparatus was designed to achieve stable osteosynthesis of bone in the treatment of fractures and after limb-lengthening procedures. Deformities of the foot usually needed operative correction before the Ilizarov apparatus was applied.
In 1968, a new hinged distraction apparatus was developed at the N. N. Priorov Central Institute of Traumatology and Orthopaedics in Russia. The principle underlying the use of this apparatus was that it must be able to assume static and dynamic loads and to reproduce the normal kinematics of the joint. Pins that pass through the axis of joint rotation and the multilink hinged design permit correction of multiplanar deformities.
In 1972, the Volkov-Oganesyan-Povarov hinged distraction apparatus was designed to correct severe deformities of the foot and ankle. In the initial phase, the design was modified several times in response to problems that were encountered. At first, the goal was to achieve maximum correction at the time that the device was applied, but neurovascular complications occurred; therefore, correction of the deformity now is limited to that which can be obtained before the application of the device.
The rate of correction (one millimeter each day) was based on the work of Ilizarov, who determined that this was the rate at which the neurovascular structures were least at risk. The time required for correction of the deformity ranges from one to three months and is dependent on the severity and rigidity of the deformity, secondary changes in the joints and soft tissues of the foot, and the patient's tolerance of the apparatus.
We debated a great deal about whether to preserve or to limit motion of the ankle joint. We attempted to preserve the active range of motion of the ankles that had a functional range of motion before correction of the deformity. It was usually difficult to regain the degree of passive motion that was present before the distraction. In the ankle joints with little or no motion, a fibrous fusion occurred, but osseous fusion did not. The duration of immobilization in a plaster cast was based on our experience and the status of the foot before correction of the deformity. We hope to develop a method of maintaining and improving motion of the ankle joint.
On the basis of our results, we believe that severe equinocavovarus deformities of the foot can be corrected without an open procedure. Despite the severity of the deformity, as well as recurrent ulceration and infection, our patients did not choose an amputation because of the poor quality of prosthetics in Russia. With our apparatus, the deformity was corrected sufficiently for most patients to return to their former employment. Even those who could not work had some improvement in the quality of life in that they were not confined to the house and totally dependent on others to fulfill their essential needs.