RESUMEN
With a cadaveric model, we studied the effects on the superior labrum-biceps tendon complex of a fall on the outstretched hand to assess one of the supposed mechanisms of creation of superior labrum anterior-posterior (SLAP) lesions. Ten shoulders were used to simulate either a forward or a backward fall with a custom shoulder-testing apparatus capable of simulating muscle forces, attached to a servohydraulic testing machine (INSTRON 8500+). Impaction of the humeral head on the glenoid cavity was applied in 0.1 seconds. The presence or absence of a SLAP lesion was determined. For the 5 shoulders used to simulate a forward fall, 5 type II SLAP lesions were found; for the 5 shoulders used to simulate a backward fall, only 2 type II SLAP lesions were observed. The role of shearing forces seems to be a major factor in the pathogenesis of these lesions, in association with predisposing anatomic factors.
Asunto(s)
Accidentes por Caídas , Traumatismos del Brazo/etiología , Lesiones del Hombro , Anciano , Anciano de 80 o más Años , Traumatismos del Brazo/fisiopatología , Fenómenos Biomecánicos , Cadáver , Femenino , Humanos , Masculino , Modelos Biológicos , Articulación del Hombro/fisiopatologíaRESUMEN
The authors present an original fixation technique for olecranon fractures in children, achievable without opening the fracture site. The standard method of Kirschner wire fixation with tension band wiring is replaced by a threaded pin stabilization with adjustable lock effect. An olecranon fracture model was used to compare the mechanical properties of this new system with the tension band wiring technique, and with a simple pin fixation. No significant difference was found between the two first techniques, whereas the simple pin fixation had much poorer mechanical properties.