leaving it in place may lead to cortical atrophy and a higher risk of refracturing.as a rule of thumb, fixation material should be removed within about 18 months after consolidation of the fracture.can be partially compensated for by remodeling of the bone (except for rotational malunion).common sites: scaphoid bone, femoral neck, tibial shaft.fracture healing does not occur within 6-9 months.fracture healing takes about twice as long as expected for a specific location.Normal fracture healing can be disrupted in numerous ways: If internal fixation leaves a gap of even less than 1 mm between fragments, Haversian remodeling is preceded by the laying down of woven bone scaffolding, after which lamellar bone is deposited perpendicular to the long axis. Otherwise, this must be regarded as a sign of instability (irritation callus). Capillaries can then occupy the newly-formed cavities and are accompanied by endothelial cells and osteoblast progenitor cells that form lamellar bone from osteons primarily oriented in the axial direction (Haversian remodeling). In stable osteosynthesis, there should be no formation of periosteal callus. This is the aim of rigid internal fixation. The process is initiated by osteoclasts forming cutting cones that traverse the fracture line at 50-100 µm/day. Average healing times of common fracturesĬontact healing occurs between directly apposed fragments when there is less than 0.1 mm distance and neutralisation of interfragmentary strain. In children, remodeling occurs faster than in adults and may compensate for malunion to some degree. This is an ongoing process that may last for several years.
The mesh of woven bone is then replaced by lamellar bone, which is organized parallel to the axis of the bone.Įventually, remodeling of the bone takes place, restoring its normal cortical structure depending on load distribution. The newly formed callus is still damageable by shear forces, whereas axial traction and pressure promote matrix formation.
They produce an extracellular organic matrix of fibrous tissue and cartilage, wherein woven bone is deposited by osteoblasts. Progenitor cells within the granulation tissue proliferate and begin to differentiate into fibroblasts and chondroblasts.
On radiographs, there may be increased lucency of the fracture during this stage due to bone resorption. Within 7-14 days, granulation tissue is formed between the fragments, leading to vascularization of the hematoma. Within 48 hours, chemotactic signaling mechanisms attract the inflammatory cells necessary to promote the healing process. The fracture hematoma initiates the healing response. The bridging callus seen on radiographs mainly arises from the periosteum. The periosteum, endosteum, and Haversian canals are the sources of pluripotent mesenchymal stem cells that initiate the formation of the healing tissues. Though the healing process of a fracture can be divided into various phases, it should rather be understood as a biological continuum. This is the most common 'natural' healing process, whereby the fracture ends are placed close to each other (but not apposed), with intervening hematoma and variable displacement and/or angulation. spontaneous (indirect/secondary) healing.The process of healing is different depending on the configuration of the fracture fragments and can be divided into three main categories: mechanical rest: this can be achieved by not moving and external immobilization, e.g.For normal fracture healing to occur a number of requirements must be met:
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