The major finding of the current study was the higher stability of pedicle screws over lateral mass fixation with respect to primary stability and stability after cyclic loading. From a biomechanical point of view the use of pedicle screws in the subaxial cervical spine seems justified in patients with poor bone quality and need for multisegmental fixation.

The biomechanical behavior of the osteosynthesis depends more on plate configuration than plate type. Advantages of locking compression plates are only significant if compared with dorsal plate application techniques. Nevertheless, locking compression plates are helpful supplementary tools for achieving primary stable fracture fixation. This might be of considerable clinical relevance in patients with diminished bone mineral quality or in the presence of metaphyseal comminution.

Bone-implant anchorage was different between locking and nonlocking plate constructs and depended on BMD. While in good bone quality implant choice was not critical, both locking plates provided superior resistance against screw loosening as compared to the CRP at low BMD values (<420 mg/cm). Based on our laboratory results, we conclude that locking plates such as the LCP and DHP are constructs designed to keep anatomical reduction in the presence of comminution and poor bone quality in a low intra-articular fracture of the distal humerus.

CRIF does not meet the demands for equine long-bone fracture treatment. With respect to biomechanical properties, DCP, LC-DCP, and LCP constructs did not show critical differences so other factors may direct clinical selection of these implants. We prefer the LCP implants because of the high yield strength, high stiffness under high-load application, and the least movement at the fracture line.

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In cases of bone density of >0.6 g/cm3 in the proximal femur (DEXA), the standard implants for the fixation of unstable trochanteric fractures could guarantee fixation without cutting out. The critical value of sufficient bone density in our few cases seems to be around 0.6 g/cm3 as measured by DEXA. Further investigation is needed to define the limits of bone mineral density for a successful osteosynthesis. An appropriate augmentation of the trabecular bone of the femoral head or a new design of the central loading device could increase the load-bearing capacity and thus help to reduce the cutting out phenomenon. Another alternative could be the primary implantation of an endoprosthesis in the treatment of these patients.

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