Fracture Healing and Nonunion Dynamics
Summary
Fracture healing is a complex physiological process comprising overlapping phases of inflammation, repair and remodelling. In the early inflammatory phase, haematoma formation and recruitment of immune cells set the stage for mesenchymal stem-cell migration. During repair, a soft callus composed of fibrous tissue and cartilage provides initial stability and is progressively replaced by woven bone through endochondral and intramembranous ossification. The final remodelling phase restores the normal bone architecture under mechanical loading. Successful healing depends on a finely tuned interplay of cellular differentiation, growth-factor signalling, vascular ingrowth and biomechanical stability. When this cascade fails to progress, a nonunion may develop, affecting up to 10% of long-bone fractures. Nonunions are broadly classified as hypertrophic, indicating biological activity hindered by inadequate stability, or atrophic, where diminished vascularity and cellular function lead to biological inertia. Systemic factors such as diabetes, smoking and advanced age, together with local factors including infection, soft-tissue damage and insufficient fixation, elevate the risk. Nonunions impose substantial healthcare costs and long-term morbidity worldwide, driving research into novel imaging diagnostics, biomaterials, pharmacological adjuvants and regenerative therapies to re-establish bone continuity and function.
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Fracture Healing and Nonunion Dynamics publication trend
The graph below shows the total number of articles in fracture healing and nonunion dynamics across all publications each year (not limited to Nature Index journals).
Technical terms
Callus: The temporary tissue (fibrous and cartilaginous) that forms around a fracture to stabilise and guide new bone deposition.
Endochondral ossification: The process by which cartilage is progressively replaced by bone during fracture repair and skeletal development.
Nonunion: A failure of normal fracture healing, defined by lack of progression to cortical continuity within an expected timeframe.
Osteogenesis: The formation of bone by differentiation of osteoprogenitor cells into bone-forming osteoblasts.
Angiogenesis: The growth of new blood vessels essential for delivering oxygen, nutrients and reparative cells to the healing site.
18F-sodium fluoride PET/CT: A molecular imaging technique using fluoride-based radiotracers to assess regional bone metabolic activity.
Near-infrared spectroscopy (NIRS): A non-invasive optical method for measuring tissue haemoglobin oxygenation and perfusion in situ.
References
- [18F]NaF PET/CT to assess bone healing capacity in orthopaedic trauma surgery: a feasibility study. European Journal of Nuclear Medicine and Molecular Imaging (2025).
- Near-Infrared Spectroscopy Allows for Monitoring of Bone Fracture Healing via Changes in Oxygenation. Journal of Functional Biomaterials (2024).
- 3D Printing of Tricalcium Phosphate/Poly Lactic-co-glycolic Acid Scaffolds Loaded with Carfilzomib for Treating Critical-sized Rabbit Radial Bone Defects. International Journal of Bioprinting (2024).
- The risk of non-union per fracture: current myths and revised figures from a population of over 4 million adults. Acta Orthopaedica (2017).
- Incidence, Costs and Predictors of Non-Union, Delayed Union and Mal-Union Following Long Bone Fracture. International Journal of Environmental Research and Public Health (2018).
- Fracture Non-Union: A Review of Clinical Challenges and Future Research Needs. Malaysian Orthopaedic Journal (2019).
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