Initial promising results of the dynamic locking blade plate, a new implant for the fixation of intracapsular hip fractures: results of a pilot study.

INTRODUCTION: The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. Only when the anatomical reduction is secured by stable fixation, revascularisation of the femoral head can take place and the fracture can heal by primary osteonal reconstruction. The common implants lack rotational and/or angular stability. Also the relative large volume of the implants within the femoral head compromises the (re)vascularisation. The combination of an anatomical reduction and a low volume, dynamic implant, providing angular and rotational stability seem to be crucial factors in the treatment of intracapsular hip fractures. This assumption formed the starting point for the development of the dynamic locking blade plate (DLBP), a new implant for the internal fixation of intracapsular hip fractures. This report describes the first clinical results of the new implant. PATIENTS AND METHODS: Internal fixation with the DLBP was performed in 25 consecutive patients with an intracapsular hip fracture within 24 h from admission. Failure of fixation, due to non-union, avascular necrosis, implant failure or secondary displacement of the fracture, was the primary outcome measurer. Functional outcome was assessed by the Harris Hip Score. RESULTS: Following internal fixation of intracapsular hip fractures with the DLBP, a failure rate of 2 out of 25 patients and excellent functional results were seen after a follow-up of more than 2 years. CONCLUSION: The initial clinical results of the DLBP are promising and justify the start of a randomised controlled trial.

The dynamic locking blade plate, a new implant for intracapsular hip fractures: biomechanical comparison with the sliding hip screw and Twin Hook.

Internal fixation of intracapsular hip fractures results in a high failure rate with non-union and avascular necrosis being the two most important complications. In order to prevent these possible complications treatment should consist of an anatomical reduction and stable fixation by insertion of a low volume, dynamic implant, providing angular and rotational stability to the femoral head. According to these principles a new implant, the dynamic locking blade plate (DLBP) was designed for the fixation of intracapsular hip fractures. We performed a biomechanical analysis in synthetic bone to compare the rotational stability and cut out resistance of the DLBP with a conventional sliding hip screw (SHS) and the more recently developed Twin Hook. The rotational stability of the DLBP proved to be three times higher than the rotational stability of a SHS and two times higher than the Twin Hook. There was no major difference in cut out resistance between the different implants. The design of the DLBP and possible advantages with regard to the healing of an intracapsular hip fracture are discussed.

Design of an intramedullary leg lengthening device with a shape memory actuator.

The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov in the late 1960's. This technique has, despite its proven abilities for leg lengthening and correction of angular deformities, some considerable disadvantages for the patients. Discomfort, infections and restricted weight bearing are some reasons for the development of a completely intramedullary device for leg lengthening. The device developed at the Laboratory of Biomechanical Engineering, University of Twente, is a telescopic intramedullary nail with a maximum diameter of 13 mm, which can be lengthened with 0.5 mm steps induced by a shape memory alloy actuator. The electrical energy for the actuator is supplied from outside the body by inductive coupling of two solenoid coils. Internally, the electrical energy is transformed to thermal energy by Thermofoils and Peltier-elements.