Fractures of the distal femur are rare and severe. The estimated frequency is 0.4% with an epidemiology that varies: there is a classic bimodal distribution, with a frequency peak for men in their 30s and a peak for elderly women; however, at present it is found predominantly in women and in the elderly with more than 50% of patients who are over 65. The most common mechanism is an indirect trauma on a bent knee, and more rarely direct trauma by crushing. The anatomy of the distal femur explains the three major types of fracture. Because of the anatomy of the distal femur, only surgical treatment is indicated to stabilize the fracture. A non-surgical treatment is a rare option. The aim of this report was to provide an update on the existing surgical solutions for the management of these fractures and describe details of the surgical technique applicable to these injuries. Recent radiological, clinical and biomechanical data published in the literature are reported to compare different surgical options.
Numerous biomechanical studies using osteoarticular complex need frozen cadaveric specimens. Some of these studies deal with the resistance of the tendinous structures, for example the resistance of some autografts, such as the patellar ligament and the semitendinosus and gracilis tendons for reconstruction of the anterior cruciate ligament. The aim of this study was the in-vitro evaluation of the mechanical modifications induced by freezing/thawing on human tendons. The long head of the biceps brachii tendon was used as the reference. Eight pairs of tendons of the long head of the biceps brachii were taken from eight fresh cadavers. After drawing lots, one was tested immediately, the other was deep-frozen and then thawed. With an Instron material-testing machine, we performed a relaxation test and a uniaxial tensile test, to estimate the ultimate tensile failure and the elastic modulus of each pair of tendons. Freezing had no influence on the tendinous relaxation, but altered significantly the ultimate tensile failure and Young's modulus of the tendons.
Femoral neck fracture puts at risk functional prognosis in young patients and can be life-threatening in the elderly. The present study reviews methods of femoral head vascularity assessment following neck fracture, to address the following issues: what is the risk of osteonecrosis? And what, in the light of this risk, is the best-adapted treatment to avoid iterative surgery? Femoral head vascularity depends on retinacular vessels and especially the lateral epiphyseal artery, which contributes from 70 to 80% of the femoral head vascular supply. Fracture causes vascular lesions, which are in turn the prime cause of necrosis. Other factors combine with this: hematoma tamponade effect, reduced joint space and increased pressure due to lower extremity positioning in extension/internal rotation/abduction during surgery. Head deformity is not due to direct cell death but to the repair process originating from the surrounding living bone. In post-traumatic necrosis, proliferation rapidly invades the head, with significant osteogenesis. Pathologic fractures occur at the boundary between the new and dead bone. Many techniques have been reported to help assess residual hemodynamics and risk of necrosis. Some are invasive: superselective angiography, intra-osseous oxygen pressure measurement, or Doppler-laser hemodynamic measurement; others involve imaging: scintigraphy, conventionnal or dynamic MRI. The future seems to lie with dynamic MRI, which allows a new classification of femoral neck fractures, based on a non-invasive assessment of femoral head vascularity.
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