Which fracture pattern is characterized by the fracture line running obliquely across the bone shaft at an angle of approximately 45 degrees to the long axis?

Explanation

## Fracture Classification by Line Direction **Key Point:** An oblique fracture has the fracture line running at an angle (typically 45°) across the bone shaft, neither perpendicular nor helical to the long axis. ### Mechanism and Biomechanics Oblique fractures result from combined shear and axial forces applied to the bone. The 45° angle represents the plane of maximum shear stress in the bone under combined loading conditions. ### Comparison of Fracture Patterns by Line Direction | Fracture Type | Angle to Long Axis | Mechanism | Stability | Example | | --- | --- | --- | --- | --- | | Transverse | 90° (perpendicular) | Direct blow; bending force | Unstable | Femoral shaft from direct trauma | | Oblique | 45° (angled) | Shear + axial force | Moderately unstable | Tibia from twisting with compression | | Spiral | Helical around shaft | Torsional (rotational) force | Unstable; soft tissue damage | Fibula from twisting injury | | Greenstick | Incomplete; one cortex intact | Bending in children | Stable | Pediatric radius fracture | **High-Yield:** Oblique fractures have: - Greater surface area at the fracture site (better for healing) - Tendency to shorten and angulate - Moderate instability requiring fixation - Better healing potential than transverse fractures due to increased contact area **Clinical Pearl:** Oblique fractures of long bones are prone to shortening during healing and may require operative fixation (plates, intramedullary nails) to maintain length and alignment, especially in the femur and tibia. **Mnemonic:** **OBL** — **OBL**ique = **45°** angle (remember: neither straight across nor spiraling).