Lateral rim variable angle locked plating versus tension band wiring of simple and complex patella fractures: a biomechanical study.

INTRODUCTION: Treatment of both simple and complex patella fractures is a challenging clinical problem. Although tension band wiring has been the standard of care, it can be associated with high complication rates. The aim of this study was to investigate the biomechanical performance of recently developed lateral rim variable angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures. MATERIALS AND METHODS: Sixteen pairs of human anatomical knees were used to simulate either two-part transverse simple AO/OTA 34-C1 or five-part complex AO/OTA 34-C3 patella fractures by means of osteotomies, with each fracture model created in eight pairs. The complex fracture pattern was characterized by a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral, and an inferior (central distal) fragment mimicking comminution around the distal patellar pole. The specimens with simple fractures were pairwise assigned for fixation with either tension band wiring through two parallel cannulated screws or a lateral rim variable angle locking plate. The knees with complex fractures were pairwise treated with either tension band wiring through two parallel cannulated screws plus circumferential cerclage wiring or a lateral rim variable angle locking plate. Each specimen was tested over 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive knee flexion within the range of 90° flexion to full extension. Interfragmentary movements were captured via motion tracking. RESULTS: For both fracture types, the articular displacements measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following the lateral rim variable angle locked plating compared with tension band wiring, p ≤ 0.01. CONCLUSIONS: From a biomechanical perspective, lateral rim variable angle locked plating of both simple and complex patella fractures provides superior construct stability versus tension band wiring under dynamic loading.

Anterior variable-angle locked plating versus tension band wiring of simple and complex patella fractures - a biomechanical investigation.

BACKGROUND: The aim of this study was to investigate the biomechanical performance of novel anterior variable-angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures. METHODS: Sixteen pairs of human cadaveric knees were used to simulate two-part simple transverse AO/OTA 34-C1 and five-part complex AO/OTA 34-C3 patella fractures. The complex fracture pattern was characterized with a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral and an inferior fragment mimicking comminution around the distal patella pole. Eight pairs with simple fractures were split for fixation via either tension band wiring (TBW) through two parallel cannulated screws or anterior variable-angle locked plating, whereas other eight pairs with complex fractures were split for either TBW through two parallel cannulated screws plus circumferential cerclage wiring, or anterior variable-angle locked plating using a cortical caudo-cranial polar screw. Each specimen was tested over 5000 cycles with a range of motion from 90° flexion to full extension by pulling on the quadriceps tendon. Interfragmentary movements were captured by motion tracking. RESULTS: For both fracture types, the longitudinal and shear articular displacements, measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following anterior variable-angle locked plating versus TBW, p ≤ 0.01. CONCLUSIONS: From a biomechanical perspective, anterior locked plating of both simple and complex patella fractures resulted in less interfragmentary displacement under extended cyclic loading.

El peroné flotante: resultado de una luxación tibioastragalina pura con lesión de la articulación tibioperonea proximal: reporte de caso / The floating fibula: outcome of pure tibiotalar dislocation with lesion to the proximal tibiofibular joint: case report

ANTECEDENTES El peroné flotante tras un traumatismo de alta energía es una entidad muy poco frecuente. Este es el primer reporte de caso asociado a luxación del tendón bicipital. OBJETIVO Presentar un caso de peroné flotante tras luxación divergente de tobillo asociado a luxación peronea proximal. MATERIALES Y MÉTODOS Mujer de 17 añ que, tras accidente de tráfico, sufrió caída y presentó dolor y deformidad del tobillo izquierdo, junto con dolor e impotencia funcional de la rodilla ipsilateral. En las radiografías, se apreció una luxación pura divergente del tobillo izquierdo de tipo IV. Se realizó reducción cerrada en urgencias. El estudio se complementó con una resonancia magnética que mostró una rotura completa de la sindesmosis y del ligamento deltoideo, así como una fractura no desplazada de la meseta tibial externa, junto con un desgarro de la cápsula tibioperonea proximal y desprendimiento completo del ligamento lateral externo y del tendón bicipital desde su inserción en la cabeza del peroné. Se realizó reanclaje de la sindesmosis y del ligamento deltoideo, así como del ligamento lateral externo y del tendón bicipital mediante anclajes óseos metálicos y reducción de peroné tanto proximal como distalmente, mediante sistema de sutura tipo botón. Se inmovilizó con férula cruropédica por cuatro semanas. RESULTADOS La paciente presentó recuperación completa de la fuerza a los cinco meses de seguimiento, con movilidad completa del tobillo y de la rodilla. CONCLUSIÓN El peroné flotante es muy poco frecuente; sólo se ha descrito un caso en la literatura. Implica la disrupción de la articulación tibioperonea proximal y distal, lo que puede provocar inestabilidad en la rodilla y en el tobillo. Por tanto, ante un traumatismo de alta energía en el tobillo, es necesaria la exploración minuciosa de la rodilla ipsilateral.

BACKGROUND Floating fibula after high-energy trauma is a very uncommon entity. The present is the first report of a case associated with avulsion of the bicipital tendon. PURPOSE To present a case of floating fibula after divergent ankle dislocation associated with proximal peroneal dislocation. MATERIALS AND METHODOS A 17-year-old woman who fell after a traffic accident and presented pain and deformity of the left ankle with pain and functional impotence in the ipsilateral knee. The radiographs showed a pure divergent type-IV left-ankle dislocation. Closed reduction was performed in the emergency room. The study was complemented with a magnetic resonance imaging scan which showed complete rupture of the syndesmosis and the deltoid ligament, as well as a non-displaced fracture of the external tibial plateau together with a tear of the proximal tibiofibular capsule and complete detachment of the external lateral ligament and bicipital tendon from its insertion in the peroneal head. The syndesmosis and deltoid ligament were reanchored, as well as the external lateral ligament and the bicipital tendon, using metallic bone anchors and fibula reduction both proximally and distally, using a suture-button system. The patient was immobilized with a long-leg splint for four weeks. RESULTS The patient presented complete recovery of strength at five months of follow-up. CONCLUSSION Floating fibula is a rare entity, with only one case described in the literature. It involves a disruption of the proximal and distal tibiofibular joint, which can lead to knee and ankle instability. Therefore, in cases of high-energy trauma to the ankle, a careful examination of the ipsilateral knee is necessary.