Foot Deformity Correction with Hexapod External Fixator, the Ortho-SUV Frame™

Postdoctoral Fellow, Department of Orthopaedic Surgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
The Journal of foot and ankle surgery: official publication of the American College of Foot and Ankle Surgeons (Impact Factor: 0.85). 03/2013; 52(3). DOI: 10.1053/j.jfas.2013.01.013
Source: PubMed


External fixators enable distraction osteogenesis and gradual foot deformity corrections. Hexapod fixators have become more popular than the Ilizarov apparatus. The Ortho-SUV Frame™ (OSF; Ortho-SUV Ltd, St. Petersburg, Russia), a hexapod that was developed in 2006, allows flexible joint attachment such that multiple assemblies are available. We assessed the reduction capability of several assemblies. An artificial bone model with a 270-mm-long longitudinal foot was used. A 130-mm tibial full ring was attached 60 mm proximal to the ankle joint. A 140-mm, two-third ring forefoot was attached perpendicular to the metatarsal bone axis. A 130-mm, two-third ring hindfoot was attached parallel to the tibial ring. A V-osteotomy, which was combined with 2 oblique osteotomies at the navicular-cuboid bone and the calcaneus, was performed. The middle part of the foot, including the talus, was connected to the tibial ring. We assessed 5 types of forefoot applications and 4 types of hindfoot applications. The range of correction included flexion/extension in the sagittal plane, adduction/abduction in the horizontal plane, and pronation/supination in the coronal plane. Additionally, we reported the short-term results in 9 clinical cases. The forefoot applications in which the axis of the hexapod was parallel to the axis of the metatarsal bones had good results, with 52°/76° for flexion/extension, 48°/53° for adduction/abduction, and 43°/51° for pronation/supination. The hindfoot applications in which the hexapod encircled the ankle joint also had good results, with corresponding values of 47°/58°, 20°/35°, and 28°/31°. Clinically, all deformities were corrected as planned. Thus, multiple assemblies and a wide range of corrections are available with the OSF.

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    ABSTRACT: This study compared the six-axis external fixator Ortho-SUV Frame (OSF) and the Ilizarov apparatus (IA) in femoral deformity correction. Our specific questions were: (1) which of the fixators (OSF or IA) provides shorter period of femoral deformity correction, and (2) which of the fixators (OSF or IA) provides better accuracy of correction. We retrospectively analysed 123 cases of femoral deformities (127 femora): 45 (47) treated with OSF (20 male and 27 female) and 78 (80) with IA (53 male and 27 female). The average age in the OSF group was 34.6 (range, 18-66) and in the IA group 35.8 (range, 18-76). All the deformities were categorized according to the number of planes and deformity components as simple, middle and complex deformities. Elimination of simple deformities in the IA group took 58.3 ± 21.4 days, EFI 58.8 ± 39.8 days/cm, and lengthening was 4.6 ± 1.98 cm. Middle deformities were 71.3 ± 26.2, 61.9 ± 30.3 and 4 ± 2, respectively. In complex deformities we had 105.2 ± 21.8, 79.3 ± 35.4 and 3.2 ± 1.45, respectively. Normal alignment was achieved in 55.0 % of cases in IA. In 45.0 % of cases we had residual deformity. Elimination of simple deformations in the OSF group took 55.3 ± 12.8 days, EFI 47.5 ± 23 days/cm, and lengthening 4.5 ± 1.1сm. Middle deformities were 43.6 ± 18.9, 59 ± 14.6 and 3.6 ± 2, respectively. In complex deformities we had 44.9 ± 11.5, 57.5 ± 9.4 and 3.6 ± 1.7, respectively. In the OSF group normal alignment was achieved in 85.1 %. In 14.9 % there was residual deformity. Using OSF simplifies deformity correction and reduces its period by 2.3 times in complex deformities and by 1.6 times in middle deformities. Accuracy of correction with OSF was significantly higher than correction with IA.
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