Mechanical Failure of the OrthoPediatrics PediPlate in Late-Onset Tibia Vara with Moderate Deformity

Abstract

Late-onset tibia vara typically affects obese children and adolescents. While varus of the proximal part of the tibia is the primary deformity, there may be associated varus or valgus of the distal part of the femur1,2. Tibia vara may be classified as mild, moderate, or severe, based upon the mechanical axis zone3. Proximal tibial osteotomy is an option for treatment, but because of the potential morbidity associated with osteotomy, hemiepiphysiodesis is an appealing minimally invasive alternative to provide gradual correction with guided growth. Lateral hemiepiphysiodesis can be performed by permanent ablation, which relies upon precise timing to avoid under or overcorrection, or with a temporary tether with use of staples or a plate that bridges the physis4. The titanium eight-Plate (Orthofix, McKinney, Texas) was the first physeal-bridging plate system introduced, and a lower risk of extrusion and breakage has been reported when compared with the use of staples5-7. However, as use of the eight-Plate system has increased, reports of mechanical failure have surfaced. In particular, failure of the metaphyseal screw at the interface of the screw and the lateral proximal tibial cortex has been described8,9. Recently, several alternative devices have become available. These include the Hinge Plate (Pega Medical, Quebec, Canada), the Peanut plate (Biomet, Parsippany, New Jersey), and the PediPlate (OrthoPediatrics, Warsaw, Indiana)8,10. Between 2000 and 2012, our institution performed forty-six hemiepiphysiodesis procedures in thirty-seven patients with late-onset tibia vara with use of physeal-bridging plates or staples. Six procedures utilized the PediPlate. The purpose of this study is to report three children with moderate late-onset tibia vara who underwent lateral proximal tibial hemiepiphysiodesis with the PediPlate and had mechanical failure of the 4.5-mm cannulated stainless steel metaphyseal screws. To …