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3. Classification Based on Fracture Line and Pattern

• Transverse Fracture: A horizontal break across the bone.
• Oblique Fracture: A diagonal break across the bone.
• Spiral Fracture: A twisting force causes a spiral-shaped fracture.
• Comminuted Fracture: The bone is shattered into multiple fragments.
• Greenstick Fracture: An incomplete fracture common in children, where one side of the
bone bends while the other breaks.
• Avulsion Fracture: A fragment of bone is pulled away by a tendon or ligament.
• Compression Fracture: The bone is crushed, often occurring in the vertebrae.

4. Classification Based on Mechanism of Injury

• Traumatic Fracture: Resulting from high-impact trauma such as falls or accidents.
• Pathologic Fracture: Occurring due to underlying bone disease (e.g., osteoporosis,
tumors).
• Stress Fracture: Caused by repetitive stress and overuse, common in athletes.

Bone Healing Physiology

Bone healing is a highly organized biological process that restores structural integrity and
function after a fracture. The ability of bone to regenerate itself is unique among tissues and is
influenced by multiple cellular and biochemical factors. Understanding the mechanisms involved
in bone healing is crucial for guiding treatment, selecting appropriate immobilization techniques,
and preventing complications such as delayed union or nonunion.

Phases of Bone Healing

Bone healing occurs in three primary phases, each involving distinct biological and cellular
activities:

1. Inflammatory Phase (0-7 Days)
o Begins immediately after the fracture and is essential for initiating the healing
cascade.
o Hematoma Formation: Blood vessels at the fracture site rupture, leading to a
localized hematoma. This provides a matrix for healing and a source of
inflammatory mediators.
o Cellular Response: Platelets release cytokines and growth factors such as
platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-
β), which attract immune cells (macrophages and neutrophils) to clear debris and
necrotic tissue.
o Vascular Changes: Increased vascular permeability leads to edema and the
recruitment of mesenchymal stem cells (MSCs) and osteoprogenitor cells to the
site of injury.