Congenital deficiency of the fibula and associated anomalies of the lower limb represent a well-recognized clinical entity. Previous results2,15,16 have shown that lengthening and deformity correction is the preferred treatment for patients with mild to moderate leg length discrepancy with mild foot deformities (Paley types 1 and 2). Controversial cases include those with more severe foot deformities (Paley types 3 and 4) and greater leg length discrepancies.8
The techniques used in the present study had 2 variations from the original SUPERankle procedure as described by Paley.8 Paley practiced a combined SUPERankle procedure with lengthening in a single surgery, with complete resection of the fibular anlage. The current authors advocate a 2-staged procedure: deformity correction with the SUPERankle procedure followed by a lengthening procedure. The lengthening procedure was usually performed 1 to 2 years after the first procedure and was never performed before the age of 3 years. This variation helps in reducing limb lengthening complications and the incidence of ankle stiffness.7,8,17 In addition, complete resection of the fibular anlage does not completely eliminate proximal tibia valgus and is not necessary as 10 to 15 degrees varusization of the tibia at the end of the lengthening procedure can balance out the proximal tibia valgus that may occur with incomplete anlage resection.8 Moreover, complete anlage resection has a theoretical risk of injury to the common and deep peroneal nerves. The present study had only 1 case of recurrent genu valgum (Figs. 8, 9), which was treated during subsequent lengthening. Therefore, we recommend a partial resection of the fibular anlage up to the level of the apex of the deformity.
Outcomes associated with the reconstruction procedures are favorable. For example, Paley et al18 compared 22 patients treated with the SUPERankle procedure, combined with lengthening, to an age-matched group of patients who underwent Syme amputation; the results demonstrated no difference in function between the 2 groups. The big advantage of reconstruction surgery is that patient retains a sensate foot that can feel the ground, thereby providing balance and proprioception.7,8 However, Birch et al19 classified fibular hemimelia according to the number of rays of the foot and recommended amputation for most cases with less than 3 rays. The present study had 2 patients with 2 rays who underwent primary amputation as there was not enough surface area for a stable plantigrade foot.
The present study did not compare limb reconstruction to amputation because the current challenge involves improving the results of lengthening.7,8 An analysis of literature15,20,21 suggests that unsatisfactory results after a salvage procedure are mainly related to recurrent or residual foot deformities.8 For example, Naudie et al2 achieved satisfactory results in only 4 of 10 cases after lengthening and the reason for unsatisfactory outcomes involved residual or recurrent foot and tibial deformities.8 Cheng et al22 reported a similar experience in a small prospective group of 4 cases of lengthening, with unsatisfactory results secondary to recurrent tibial and foot deformities.
The current study revealed a statistically significant relationship between the age at the first surgery and recurrence of foot deformities. Hence, early treatment is important in reducing recurrence and unsatisfactory results. Five of 12 patients with an age at the first surgery of more than 5 years had recurrence, while only 1 of 15 patients with an age at the first surgery of less than 5 years had recurrence. Paley8 prefers to perform this procedure when the patient is between 18 and 24 months of age, performing lengthening at the same time. We have performed SUPERankle as early as 12 months, with lengthening performed as a next-staged procedure. Furthermore, genu valgum at the knee contributes to recurrent deformities at the ankle. As there is usually no subtalar joint present, genu valgum cannot be compensated by a mobile subtalar joint.7,8 It is therefore important to identify and treat knee valgus to improve the results of the foot correction and to help prevent recurrent ankle valgus.7,8 Despite the above precautions, recurrence is still a problem. The theoretical explanation is that by reorienting the ankle joint via supramalleolar osteotomy, the distal tibial growth plate is maloriented. This could lead to gradual recurrence, which can be addressed at the time of next staged lengthening.7,8
Previous studies have shown the effectiveness of lengthening for fibular hemimelia. Using gait analysis Johnson and Haideri23 showed that, successful lengthening resulting in plantigrade feet and well-aligned tibia, is associated with better ankle push-off strength and better knee flexion strength compared with that in patients who underwent Syme amputation.8 Furthermore, Catagni et al1 reviewed 32 patients with type 3 fibular hemimelia treated with successive lower limb lengthenings and deformity correction using the Ilizarov method; nearly equal limb length and a plantigrade foot were achieved in half of the patients. Similarly, Jawish and Carlioz11 reported good correction of the foot in 60% of cases of fibular hemimelia treated by lengthening. In addition, Paley7,8 (in his unpublished results presented at AAOS 1999, Anaheim, CA) was able to achieve good or excellent functional results, including the desired goal of lengthening, in 36 of 38 lengthened legs.8
Similarly, the present study had favorable results. According to the ASAMI scoring system, 15 of 27 cases had excellent results. Among patients classified as Paley type 1, the majority had excellent ASAMI scores and all had at least a good score. In contrast, among Paley type 3a cases, some patients had poor and fair scores. In addition, none of the type 3c cases had a score of more than fair. However, as the number of cases within each type was small, an association between Paley type and ASAMI scores could not be verified statistically. Two patients with ankle fusion were rated as fair. The ankle fusion was performed as a successful way of permanently stabilizing the foot12 and the patients did not require any additional surgeries for the ankle or foot. In addition, the present study had excellent follow-up duration, with a mean of 9.37 years and a maximum of 14 years.
In the present study, 18 of 27 patients had limbs equalized to within 1 cm. Two patients had a shortening of 1.5 cm. These patients did not require any additional surgeries and were managed with the help of a shoe rise. Patients with a shortening of more than 2 cm were lengthened again after a minimum gap of 2 years.
Limb lengthening with an external fixator alone is fraught with complications during the long external fixator period.24 Early removal of fixator will decrease most of the associated complications and can be done with the help of a lengthening over plate and recently designed slotted plates by the current author.25 Delayed union of the corticotomy site was due to frame instability, associated with a grade 2 pin tract infection and wire loosening. This was treated with debridement and wire exchange, thereby stabilizing the frame. Three patients had knee subluxation and was associated with femoral lengthening.24 This was treated by reducing the knee joint with the addition of a tibial ring.
The main limitation of the present study is that, due to relative rarity of this condition and small sample size, a comparison in functional outcomes and complications between the different Paley types was not possible.
Our long-term follow-up clearly suggests that limb reconstruction according to the Paley classification is an excellent option in the management of fibular hemimelia. Our 2-staged procedure of SUPERankle followed by lengthening with a minimum gap of 1 to 2 years helps in reducing the complications of limb lengthening and ankle stiffness. Performing the first surgery at an earlier age (below 5 y) plays a significant role in preventing recurrent foot deformities. Nevertheless, the surgeon must be thoroughly trained to get the desired result.
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Keywords:Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.
fibular hemimelia; SUPERankle procedure; Paley classification; Ilizarov