Many surgical approaches have been described in the treatment of congenital pseudarthrosis of the tibia, the most aggressive procedure being amputation. 17,18,30 However, limb salvage operations have been most common, and traditional methods in pseudarthrosis treatment such as bone grafting with internal fixation have been used. Most of the previous work compares different methods to achieve healing. 4,9,19 Transfer of the ipsilateral fibula into the pseudarthrotic site has given good results in some reports. 10,28 Microsurgery with a free vascularized fibular or iliac graft seems to be a promising procedure. 6,12,16,24,27,31,32 In addition to surgical interventions, direct current or pulsed electromagnetic fields to a pseudarthrotic defect alone or with bone grafting have been used with variable results, but two studies report a success rate of approximately 50% to 70%. 5,23
During the past 10 years methods described by Ilizarov 14,21 have become increasingly popular among orthopaedic surgeons. However, in the English language literature the number of reports on the application of the Ilizarov methods in congenital pseudarthrosis of the tibia is still relatively small and the number of patients and results differ. 11,21,25,26 Moreover, complications and problems after primary treatment with the Ilizarov external fixator have not been documented in detail. Accordingly, the aim of the current work was to evaluate the authors’ results of the Ilizarov bone transport method (bifocal distraction-compression osteosynthesis), with special emphasis given to residual postoperative deformities.
MATERIALS AND METHODS
During the 3-years, 1993 through 1995, the authors treated seven children with seven congenital pseudarthroses of the tibia (Table 1). Four children had affection of the right leg, three of the left. Fibular disease (hypoplasia or pseudarthrosis or both) was found in six patients. The median age at surgery was 3.2 years (range, 2.6–7.8 years). There were four boys and three girls, all diagnosed with neurofibromatosis (von Recklinghausen’s disease). The patients previously had one to three unsuccessful surgeries with bone grafting and various methods of internal fixation.
The current method included the Ilizarov external fixator with three rings, resection of the pseudarthrosis, and bone transport. 21 Each ring was fixed to the tibia with three, 1.5-mm Kirschner (K) wires. The fibula was transfixed to the tibia at each end and osteotomized in the middle ⅓ of the bone. Fixation of the foot in the plantigrade position was included in the external frame. Acute axial correction using temporary intramedullary fixation of the tibia with a 1.8-mm K wire was done. This wire was inserted using a retrograde technique through the calcaneus, except for one patient in whom the wire was inserted through the medial malleolus. In patients with bone resection of 3 cm or less (n = 5), acute shortening was done using a transverse skin incision. In two patients with greater than 3-cm bone resection, acute shortening of 3 cm was combined with bone transport. In all patients, an osteotomy was done using a Gigli saw in the proximal metaphysis of the tibia for the bone transport and lengthening (Fig 1). After a latency period of 7 days, a diurnal lengthening rate of 1 mm (0.25 mm four times daily) was started for callus distraction (callotasis). In two patients, the intramedullary wire was left in situ after acute correction and was removed at the end of the distraction lengthening period in one patient and kept for extended protection after frame removal in the other patient. During the lengthening and consolidation periods, full weightbearing was allowed. After complete consolidation of the lengthening zone and healing at the pseudarthrotic site, the Ilizarov external device was removed.
The patients wore plaster casts for 6 weeks after apparatus removal and thereafter an orthosis was worn for the rest of the growth period. The patients were followed up at regular intervals with clinical examinations and long radiographs taken with the patient standing to measure the alignment and juxtaarticular segmental angles in the lower limbs. 22 The opposite leg was used as a normal control. In the patient with a vascularized fibular graft from the contralateral side, donor morbidity and influence on normal growth in the control bone could not be excluded and a bilateral comparison was not done.
Primary Ilizarov Procedure
Spontaneous bone healing of the pseudarthrotic site and in the lengthening zone occurred in five patients without additional surgeries. In two patients (Table 1) bone grafting with autologous cancellous bone from the iliac crest was necessary 6.5 and 7 months postoperatively while the patients still were wearing the frame because of delayed union in the docking area. Both tibias healed within 4 months after this procedure. The median time in the fixator was 8.7 months (range, 4.4–12.2 months). The median length of the callotasis distraction zone measured with justification for magnification on the radiographs was 54 mm (range, 26–75 mm), resulting in a median lengthening index of 1.7 months (range, 0.8–2.7 months) per centimeter of lengthening.
Complications During Followup
Major complications occurred in all patients (Table 1). Four patients had five refractures. Two of the refractures occurred in the healed pseudarthrosis, one was through the callotasis zone and in Patient 2, the fracture occurred through the callotasis zone and through a wire hole in the distal segment. Both of these fractures healed after a new Ilizarov procedure and bone grafting (Fig 2). Patient 3 with refracture in the lengthening zone first was treated unsuccessfully with resection and AO plate fixation and later was treated with a new Ilizarov external fixator and autologous bone grafting. The callotasis zone healed, but later the patient experienced refracture at the original site of the congenital pseudarthrosis even with the protection of an intramedullary pin. This fracture eventually healed 5.5 months after additional surgery with a vascularized fibular graft from the contralateral leg. The measured axial values on radiographs taken with the patient standing showed increasing valgus deformity of 19° in the contralateral distal tibia at the last followup (donor morbidity).
Patient 4, who had primary surgery at the age of 3.2 years, had a refracture at the pseudarthrotic site 2 months after removal of the frame (Fig 3), even though his leg was protected with an orthosis. The patient’s guardians did not want a new Ilizarov procedure done immediately because the patient was pain-free and doing well functionally in the orthosis. At the last followup, he had good alignment, but will need a second Ilizarov procedure to achieve healing of the pseudarthrosis. He was the only patient with a normal fibula.
The last patient with refracture after primary healing (Patient 7) was a 7.8-year-old boy. He was noncompliant after frame removal and did not use his orthosis as prescribed. The tibia fractured in the pseudarthrotic area during the night when he was not wearing an orthosis. A new Ilizarov procedure was done. The patient had a satisfactory clinical result, but has a tibial valgus deformity in the proximal and distal epiphysis (Table 2).
Patient 1 had loosening of two K wires and contracture of the ankle and knee, resulting in additional surgery: wire extraction and insertion of new wires, percutaneous Achilles tenotomy, and mounting of an additional ring on the femur for reduction of knee flexion contracture. Because of anterior wire penetration in the distal fragment the pseudarthrosis healed with a major axial deformity in procurvatum and valgus. The deformity was corrected with a new Ilizarov procedure, but at the last followup the patient had a combined deformity (Tables 2, 3).
Four minor complications with temporary flexion contractures of the knee were treated successfully with a dynamic orthosis (Dynasplint Systems®, Inc, Serena Park, MD) and physiotherapy during the lengthening and consolidation periods. One patient (Patient 7) sustained an ipsilateral femoral fracture caused by adequate trauma while wearing the fixator. The problem was solved by expansion of the original frame with two femoral rings for reduction and fixation, and was not registered as a complication because of the treatment.
Status at Last Followup
At the last followup, the median age of the patients was 10.3 years (range, 9.0–14.1 years) and the postoperative period was 87 months (range, 73–94 months). Reduced range of motion (ROM) in the ankle on the affected side was seen in all patients (Table 4). There was no difference in ROM in the knee. All patients measured had an abnormal axial malalignment test with a lateral mechanical axis deviation of 10 mm or greater, indicating a valgus deformity of the entire lower extremity. In the femur, the median difference in the lateral distal femoral angle between the affected and nonaffected side was 1° valgus. In the proximal tibia, the difference in the medial proximal tibial angle showed valgus deformity in all patients (4°–14°). In the distal tibia, the difference in the lateral distal tibial angle was in valgus deformity in four patients (9°–21°) and varus in two patients (5°–15°).
In the sagittal plane, the difference in the posterior proximal tibial angle showed a median difference of 3° in recurvatum. In the distal part, the anterior distal tibial angle showed procurvatum deformity in five of six patients with values from 11° to 21°. Leg length inequality was seen in five patients, but only three patients had values for which they required adjustment (20–48 mm).
Two patients reported pain from the affected leg with a score of 30% and 15% of maximum pain, respectively, measured on a regular visual analog scale. Reduced running ability was reported by two additional patients. Except for the patient with the highest pain visual analog scale score, all patients participated in regular physical education activities in school.
All patients in the current study had neurofibromatosis, and congenital pseudarthrosis of the tibia often is seen in combination with this disease, 2,7,19,20 but fibrous dysplasia 7,8 and other conditions such as clubfoot 1 also are associated with congenital pseudarthrosis of the tibia.
Congenital pseudarthrosis of the tibia is one of the most difficult problems to treat and is a great challenge in pediatric orthopaedics. 21 According to Campanacci et al, 8 in 1981, the treatment was unsolved, and the treatment still is not optimally solved. With additional treatment of bone grafting at the docking site in two patients, all seven of the authors’ patients treated with the Ilizarov external fixator achieved primary healing of the pseudarthrosis. This is in accordance with the results of a multicenter study by Paley et al 21 who reported primary healing in 94% of patients with one treatment and 100% of patients with two treatments. In another multicenter study, the Ilizarov technique emerged as being the optimal method with a healing rate of 75.5% of the pseudarthroses. 13 Case reports by Fabry et al 11 and Plawecki et al 25 also concluded with good results when the Ilizarov bone transport method was used. Most patients seem to achieve primary healing when the Ilizarov technique 11,21,25 or ipsilateral or contralateral vascularized fibular graft methods are used. 6,10,12,28 Anderson et al 3 used an intramedullary nail and achieved bony union in nine of 10 patients and one patient needed additional bone grafting before union was achieved. However, the experience from the current study is that an intramedullary pin fixation does not necessarily protect the tibia from refracture (Patient 3).
The current results showed a high rate of complications during the treatment period. At the followup axial deformities and refractures were observed. The complications were more frequent in the youngest patients, which is in accordance with the experience of Grill et al. 13
Refractures occurred in patients operated on before the age of 4 years. The only refracture among the older children occurred during a torsional maneuver in a child who did not use his orthosis as prescribed. All refractures healed except for one that occurred in the only patient with a normal fibula that developed into a hypertrophic bone. Keret et al 15 also reported a lower healing rate in patients with congenital pseudarthrosis of the tibia and a normal fibula. However, patients with nonhealed congenital pseudarthrosis of the tibia may have satisfactory function because of stabilization from a hypertrophic, intact fibula and the use of an orthosis. The authors also found that five of the patients were able to run and only one patient required a special physical education program in school. This is a good result compared with the results of another study. 29
Equalization of preoperative leg-length inequality because of shortening attributable to axial malalignment in the pseudarthrosis and soft tissue contractures, may be difficult to achieve using a vascularized fibular graft. In addition, fibular harvest from the contralateral normal extremity may result in donor morbidity, 27 as occurred in one of the patients in the current study. This may result in late deformity correction in both legs.
The deformities in the current patients were evaluated in segmental details on two plane long-film radiographs, taken with the patient standing using the method of Paley et al. 22 A high incidence of axial malalignment was observed at the last followup. Compared with the results of Grill et al, 13 who observed valgus deformity in the distal tibia in 25% of the patients, the current authors’ numbers are higher. In the current study, patients had valgus (n = 4) and varus (n = 2) combined with procurvatum (n = 5) in the distal tibia. In the proximal tibia valgus (n = 6) occurred in combination with procurvatum (n = 2) and recurvatum (n = 3). The fact that the mechanical axis deviation in all patients showed a lateral deviation, was a result of valgus deformity in the proximal tibial metaphysis. The deformity in procurvatum distally may be the result of a nonoptimal anatomic reduction during surgery. Preoperatively, because of adaptation, the patients had good dorsiflexion in the ankle despite the procurvatum deformity, and a minor procurvatum deformity may persist after acute reduction as the position of the foot is used as reference. In the proximal tibia only small procurvatum and recurvatum deformities were observed, and clinically no difference in ROM of the knee was found.
Correct measurements of the mechanical axis in children wearing the Ilizarov frame are extremely difficult to do, because of the voluminous frame with metal components and knee and ankle contractures. Therefore, standardized long radiographs taken with the patient standing usually were obtained only preoperatively and at the last followup. Accordingly, except for one case (Patient 1), the authors cannot determine exactly whether the residual deformities occurred because of incomplete correction during surgery, inadequate fixation during lengthening, or recurrence attributable to growth after frame removal. Possibly, more than one mechanism may have contributed to the formation of late deformities.
Despite many complications the authors still prefer the Ilizarov bone transport method in the treatment of congenital pseudarthrosis of the tibia. However, it seems rational, because of the many operations usually needed in the youngest children, to wait until the child reaches 5 to 6 years, and to protect the leg with an orthosis until surgical treatment and for the rest of the growth period. It is also important to inform the patients and the parents that additional surgery may be necessary after healing of the pseudarthrosis because of residual deformity.
The authors thank Per Ludvigsen, MS, engineer at the Hospital’s Biomechanics Laboratory, for excellent technical assistance.
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