Osteoporotic Fracture Healing Mechanisms in Animal Models

Osteoporotic fracture healing is impaired by reduced bone mass and altered cellular and molecular responses, prolonging recovery and increasing morbidity. Animal models, particularly ovariectomised rodents and glucocorticoid-treated large mammals, accurately recapitulate postmenopausal and secondary osteoporosis, allowing detailed investigation of bone repair. Following fracture, a well-orchestrated sequence begins with haematoma formation, inflammation, cell recruitment and angiogenesis, before transitioning to soft callus formation via endochondral ossification and hard callus formation through intramembranous ossification. Osteoporosis disrupts this sequence by attenuating osteoprogenitor proliferation, diminishing angiogenic signalling and skewing inflammatory cytokine profiles, often exemplified by elevated pro-inflammatory mediators such as interleukin-6 and midkine. Mechanistic studies reveal that oestrogen deficiency impairs Wnt/β-catenin signalling and alters oestrogen receptor-driven gene expression, contributing to delayed chondrogenesis and mineralisation. Mechanical stimuli, including controlled whole-body vibration, further modulate these pathways, with efficacy dependent on oestrogen status. Comparative investigations in rodents and larger species highlight species-specific differences in callus structure and remodelling rates, underscoring the need for model-tailored interpretations. Together, these findings illuminate key cellular and molecular checkpoints in osteoporotic bone repair and guide the development of pharmacological and biophysical interventions to restore bone strength and accelerate fracture union.

Research from Nature Portfolio

Recent studies have established distinct effects of glucocorticoid-induced and oestrogen-deficient osteoporosis on bone repair modalities. In one foundational investigation, separate cortical drill-hole and periosteal scratch models delineated intramembranous and endochondral ossification under each osteoporotic condition. The work revealed that oestrogen deficiency more severely impaired early osteogenic differentiation in intramembranous ossification, whereas both osteoporosis types delayed chondrocyte hypertrophy during endochondral repair. In vitro assays corroborated these in vivo findings, demonstrating consistent reductions in osteoblast and chondrocyte maturation markers. This dual-model framework offers a robust platform for dissecting ossification-specific deficits in osteoporotic fracture healing and for testing targeted therapies that address each repair pathway.

Osteoporotic Fracture Healing Mechanisms in Animal Models publication trend

The graph below shows the total number of articles in osteoporotic fracture healing mechanisms in animal models across all publications each year (not limited to Nature Index journals).

Technical terms

Intramembranous ossification: Direct bone formation from mesenchymal cells without a cartilage intermediate.

Endochondral ossification: Bone repair process involving temporary cartilage callus formation before mineralisation.

Ovariectomised (OVX) model: Surgical removal of ovaries in rodents to induce oestrogen-deficiency osteoporosis.

Callus: The provisional tissue composed of cartilage and woven bone that stabilises a healing fracture.

Wnt/β-catenin signalling: Molecular pathway critical for osteoblast differentiation and bone formation.

References

1. The impact of low-magnitude high-frequency vibration on fracture healing is profoundly influenced by the oestrogen status in mice. Disease Models & Mechanisms (2014).
2. Influence of Menopause on Inflammatory Cytokines during Murine and Human Bone Fracture Healing. International Journal of Molecular Sciences (2018).
3. Inhibition of Midkine Augments Osteoporotic Fracture Healing. PLOS ONE (2016).
4. Intramembranous ossification and endochondral ossification are impaired differently between glucocorticoid-induced osteoporosis and estrogen deficiency-induced osteoporosis. Scientific Reports (2018).
5. Review of Animal Models of Comorbidities in Fracture‐Healing Research. Journal of Orthopaedic Research® (2019).
6. Advances in Animal Models for Studying Bone Fracture Healing. Bioengineering (2023).