Northcoast Physiotherapy Clinic

19/10/2025

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29/09/2025

25/09/2025

🦴✨ Stages of Bone Fracture Healing ✨🦴

After a bone fracture, an inflammatory response occurs that lasts for 2 weeks 🔥. This phase starts an intricate network of proinflammatory signals and growth factors. Polymorphonucleate (PMN) cells and macrophages 🧪 are recruited to endocyte microdebris and micro-organisms derived from the fracture. The damage to the blood vessels results in edema 💧.

📆 After 2–3 weeks from the fracture, endochondral bone formation occurs. During this process, the mesenchymal stem cells (MSCs) are recruited to the injured site and begin to differentiate into chondroblasts (chondrogenesis) 🧬, which proliferate into chondrocytes, resulting in soft calluses 🩹. Chondrocytes synthesize and secrete the cartilage matrix, containing type II collagen and proteoglycans.

🗓️ Between the 3rd and 6th week, the cartilage undergoes hypertrophy and mineralization in a spatially organized way. New MSCs are recruited which differentiate into osteoblasts, leading to the formation of interwoven bone (hard callus) 🪨. Mineralized bone formation is induced by the signaling of factors such as Bone Morphogenetic Proteins (BMP) and TGF-β2/β3 in the cartilaginous callus.

⏳ The last phase of bone remodeling begins 8 weeks after fracture and can last up to 2 years 🕰️. Communication between osteoclasts and osteoblasts mediates the replacement of braided bone with lamellar bone 🧱 through two key activities:

🔹 Removal of bone (resorption) by osteoclasts
🔹 Formation of bone matrix by osteoblasts

💪🦴 Our bones are amazing healers!

Illustration: https://cellregeneration.springeropen.com/articles/10.1186/s13619-025-00225-1

24/09/2025

24/09/2025