A 34-year-old male construction worker falls from a 15-foot scaffold onto his left arm. On examination, there is severe swelling and deformity of the mid-shaft humerus with visible angulation. X-ray shows a fracture line that spirals around the bone shaft, with the proximal fragment rotated relative to the distal fragment. The fracture does not breach the skin. What is the classification of this fracture?

Explanation

## Fracture Classification: Spiral Pattern ### Definition of Spiral Fracture A spiral fracture is characterized by a fracture line that wraps around the long axis of the bone in a helical or corkscrew pattern. This pattern results from a combination of axial compression and rotational (torsional) forces applied to the bone. ### Mechanism of Injury **Key Point:** Spiral fractures are typically caused by **twisting or rotational forces** combined with axial loading. In this case, the patient fell with the arm fixed or caught, creating a torsional moment around the humerus. ### Distinguishing Features | Feature | Spiral | Transverse | Comminuted | Segmental | |---------|--------|-----------|-----------|----------| | **Fracture line pattern** | Helical around bone axis | Perpendicular to bone axis | Multiple fragments (3+) | Two separate fracture lines; 1 floating segment | | **Force mechanism** | Torsion + compression | Direct perpendicular force | High-energy crush/impact | High-energy with segmental loss | | **Angulation** | Rotational deformity | Minimal rotation | Variable | Marked displacement | | **Soft tissue injury** | Moderate | Mild to moderate | Severe | Severe | ### Clinical Significance **High-Yield:** Spiral fractures of the humerus and femur are common in: - Falls with the limb caught or fixed - Motor vehicle accidents with rotational component - Sports injuries involving twisting mechanisms **Clinical Pearl:** The presence of rotational deformity (proximal fragment rotated relative to distal) is the hallmark finding that distinguishes spiral fractures from other patterns on clinical examination and imaging. ### Prognosis Spiral fractures typically have: - Good healing potential (large surface area for callus formation) - Risk of malunion if not properly reduced (rotational alignment must be restored) - Moderate soft tissue injury (closed in this case) [cite:Rockwood & Green's Fractures in Adults Ch 1]