Development of internal fixator systems as intelligent implants

Status:

completed 03/2008

Aims:

Fixation by means of metal implants is a well established method for treating fractures of bones. The postoperative assessment of fracture healing, however, is still difficult. Conventional radiography, clinical evaluation and manual assessment of the mobility of the fracture continue to be the most commonly used means of assessing fracture-healing in clinical practice and studies. Unfortunately, these assessments are subjective since they rely on the clinician's personal estimation of the stiffness and strength of the fracture and therefore depends largely on the expertise of the physician. In some cases it is difficult to distinguish healing problems radiologically and there is a significant radiation exposure to the patient. The aim of this research project was the development of instrumented internal fixator systems for routinely monitoring the healing process by means of noninvasive stiffness measurements. The basic technology for an instrumentation of the implants was developed in a previous work (412.02 - FR 76/Fixateur interne II). Besides optimization of the technology the main focus of the work was the clinical application of instrumented implants and the evaluation of the measured data.

Activities/Methods:

- Development of a telemetric sensor system for load measurements on implants - Biomechanical modelling - Introduction into clinical application All working packages have been successfully completed. During the project additional implants could be supplied. A clinical application of the developed system was tested with patients that had multiple operated pseudo-arthritis at the thigh bone. The improvement and extension of the technology has successfully been accomplished.

Results:

The clinical application of the system fully confirmed the fundamental and predicted concept to measure the healing process of the bone electronically under avoiding of X-ray to provide new treatment measures. Remarkably was and still is, that patients really appreciate the additional information that is provided by the developed system achieving a more deliberate and secure load of the injured extremity.

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