Biomechanical behavior of three types of fixation in the two-part proximal humerus fracture without medial cortical support.

BACKGROUND: The purpose of this study was to evaluate the role of a non-locking plate applied to the anteromedial surface of the proximal humerus on loads at the implant-bone interface of non-locking and locking lateral plate fixation of proximal humeral fractures with a medial gap. METHODS: Twenty synthetic humeri models were used. In fifteen, the proximal portion of the humerus was osteotomized to create a two-part surgical neck fracture, with a 10-mm medial gap and a 5-mm lateral gap; five models were controls. In the osteotomized humeri, five models were stabilized with a locking lateral plate (group L), five with a locking lateral plate and an anteromedial non-locking plate (group L+T), and five with a non-locking lateral plate and a non-locking anteromedial plate (group T+T). All humeri were tested under axial loading until catastrophic failure, which was characterized as complete closure of the medial gap. Stiffness was calculated using force vs. displacement curves. The data were analyzed via descriptive and inferential studies, at a 5% significance level. RESULTS: Statistically significant differences were seen among all the constructions. The combination of a lateral locking plate with an anteromedial non-locking plate (group L+T) was the stiffest construction, while the combination of a non-locking lateral plate with a non-locking anteromedial plate (group T+T) was the least stiff, even in comparison with a single locking lateral plate (p = 0.01). When the two groups which utilized a lateral locking plate (groups L+T and L) were compared, the group with additional anteromedial support demonstrated greater stiffness (p = 0.03), and stiffness values for the control group comprised of intact humeri models were even higher (p = 0.01). CONCLUSION: Combining a lateral locking plate with a non-locking anteromedial plate provides a stiffer construction for fixation of unstable two-part proximal humerus fractures with a medial gap. Mechanical benefits of medial support with a second non-locking antero-medial plate seems to be related with better construct stability in terms of strength and fatigue, potentially reducing the risk of varus collapse of the humerus head and fracture healing disturbances.

General principles for treatment of femoral head fractures.

Femoral head fractures occur almost exclusively as a result of a traumatic hip dislocation. Treatment is typically an emergency and includes the reduction of the dislocated hip under anesthesia. As a rule, the earlier the reduction, the better the outcome. Open reduction and internal fixation of the fracture of the femoral head is the treatment of choice for most young patients. In some selected cases when there is a very small fragment located in the region below the fovea, removal should be indicated. In elderly patients and those who experience severe femoral head impaction, it is preferable to perform a total hip replacement. Despite optimal management, the rate of complications after femoral head fractures may reach as high as 50%. In the present study, the authors review the general principles of management of patients with femoral head fractures.

Radiographic analysis of factors predisposing toward tendon tears in the knee extensor mechanism.

OBJECTIVES: to review radiographs of patients who suffered tendon tears of the knee extensor apparatus and observe alterations that might be factors predisposing toward this type of injury. METHODS: we retrospectively analyzed 60 cases of injury to the knee extensor mechanism that were treated surgically at the Miguel Couto Municipal Hospital between March 2004 and March 2011. Four patients were excluded due to poor quality of the examination. RESULTS: of the 56 patients evaluated, 23 were considered to be normal and 33 presented radiographic alterations. Among these, eight (24.3%) presented suprapatellar osteophytes alone; seven (21.2%), infrapatellar calcification; seven (21.2%), suprapatellar calcification; six (18.2%), supra- and infrapatellar osteophytes; and five (15.1%), infrapatellar osteophytes alone. CONCLUSION: radiographic alterations were frequently observed in patients with extensor mechanism tears.

OBJETIVOS: revisar radiografias de pacientes vítimas de rupturas tendinosas do aparelho extensor do joelho e observar alterações que possam ser um fator predisponente a esse tipo de lesão. MÉTODOS: analisamos, retrospectivamente, 60 lesões do mecanismo extensor do joelho, tratadas cirurgicamente no Hospital Municipal Miguel Couto, de março de 2004 a março de 2011, e quatro pacientes foram excluídos por má qualidade do exame. RESULTADOS: dos 56 pacientes avaliados, 23 foram considerados normais e 33 apresentaram alterações radiográficas, oito (24,3%) com presença de osteófito suprapatelar isolado, sete (21,2%) com calcificação infrapatelar, sete (21,2%) com calcificação suprapatelar, seis (18,2%) com osteófitos supra e infrapatelares e cinco (15,1%) com osteófito infrapatelar isolado. CONCLUSÃO: as alterações radiográficas foram frequentes em pacientes com ruptura do mecanismo extensor.