Research Database PMU-SQQUID

PMU-Authors

Abstract

An interdisciplinary study based on animal experiments, cell culture studies, and finite element models is presented. In a sheep model, the influence of the osteotomy gap size and interfragmentary motion on the healing success was investigated. Increasing gap sizes delayed the healing process, Increasing movement stimulated callus formation but not tissue quality. Typical distributions of intramembranous bone, endochondral ossification, and connective tissue in the fracture gap are quantified. The comparison of the mechanical data determined by a finite element model with the histologic images allowed the attribution of certain mechanical conditions to the type of tissue differentiation. Intramembranous bone formation was found for strains smaller than approximately 5% and small hydrostatic pressure (<0.15 MPa). Strains less than 15% and hydrostatic pressure more than 0.15 MPa stimulated endochondral ossification. Larger strains led to connective tissue. Cell culture studies on the influence of strain on osteoblasts supported these findings. Proliferation and transforming growth factor beta production was increased for strains up to 5% but decreased for larger strains. Osteoblasts under larger strains (>4%) turned away from the principal strain axis and avoided larger deformations. It is hypothesized that gap size and the amount of strain and hydrostatic pressure along the calcified surface in the fracture gap are the fundamental mechanical factors involved in bone healing.

Useful keywords (using NLM MeSH Indexing)

Animals

Bony Callus/anatomy*

histology

Bony Callus/physiology

Cartilage/physiology

Cell Division/physiology

Cells, Cultured

Connective Tissue/anatomy*

histology

Disease Models, Animal

Finite Element Analysis

Fracture Fixation

Fracture Healing/physiology*

Fractures, Bone/pathology

Fractures, Bone/physiopathology

Fractures, Bone/surgery

Humans

Hydrostatic Pressure

Metatarsal Bones/injuries

Metatarsal Bones/pathology

Metatarsal Bones/physiopathology

Metatarsal Bones/surgery

Movement

Osteoblasts/metabolism

Osteoblasts/physiology

Osteogenesis/physiology

Sheep

Stress, Mechanical

Transforming Growth Factor beta/metabolism