Rekonstruktion segmentaler Knochendefekte: Stellenwert der Spongiosaplastik

Development and validation of a parametric human mandible model to determine internal stresses for the future design optimization of maxillofacial implants

Large segmental mandible bone defects still represent a challenge for endogenous regeneration. Despite the bone's capacity to heal in many clinical situations, bone defects over a critical size do not heal spontaneously. An emerging treatment of critically sized mandibular defects is the implantation of individually manufactured scaffolds consisting of biodegradable magnesium alloys. Biomedical engineers faced the challenge of developing a scaffold structure that not only provides sufficient stability, but also stimulates and promotes bone growth while considering the degradation of the magnesium alloy. The porosity of the scaffold must also support bone ingrowth and neovascularization. For an optimal design and subsequent structural optimization knowledge of external load cases is essential. However, currently the muscle and joint forces of the mandible cannot be measured directly. The aim of our study was therefore the development of a parametric human mandible model to determine the relevant boundary conditions for the subsequent structural optimization of individual jawbone implants. Using a model-based approach, determining the essential external load of the mandible as a function of the age and sex of a patient individually and the realistic simulation of the mechanical stress for patient-specific loads and anatomies has been realized. The developed model is successfully validated by evaluating the deformations and stresses of the lower jaw of a possible patient and comparing them with the results of dental research. Based on the results of the modelling, in a subsequent optimization process section forces at the interface between the bone tissue and jawbone implant can be determined and used to optimize the design of the jawbone implant.

Donor site complications following anterior iliac crest bone graft for treatment of distal radius fractures

INTRODUCTION

In distal radius fractures with metaphyseal comminution, bone grafting or the use of a bone substitute may be necessary. Harvesting autologous iliac crest bone graft for other orthopedic procedures has complications. The aim of this study was to evaluate the complication rate after harvesting a small amount of bone as used for the treatment of radius fractures.

PATIENTS AND METHODS

Patients treated in a single level I trauma center with surgical treatment for distal radius fracture with iliac crest bone graft between January 2008 and December 2012 were included in this retrospective study. Patients' records were evaluated and clinical evaluation was performed at follow-up.

RESULTS

42 patients (20 females, 22 males, mean age 56.3 ± 15.9 years) were included in this study. Follow-up was mean 6.3 ± 1.2 years. Only minor complications such as hematoma could be identified; in one patient, revision surgery for bleeding was performed. No nerve injuries, long-term pain, fractures, infections or wound healing disturbances could be seen. The use of a drain of hemostyptics, the type of wound closure or pattern of harvested bone did not influence complication rate.

CONCLUSION

This study shows that harvesting a small amount of iliac crest bone graft for the treatment of distal radius fractures is a safe procedure with a very low complication rate.