The dynamic hip screw (DHS) is contraindicated in which fracture pattern and why?

• A Basicervical fractures — risk of medial migration of the lag screw
• B Unstable subtrochanteric fractures — the fracture is below the effective fixation zone, causing excessive implant stress and failure ✓
• C Stable intertrochanteric fractures (AO 31-A1) — overtly rigid for a stable pattern
• D Pathological fractures — insufficient purchase in malignant bone

Explanation

The DHS/sliding hip screw provides excellent stability for stable and unstable intertrochanteric fractures (AO 31-A1/A2) through a controlled collapse mechanism. However, in subtrochanteric fractures (below the lesser trochanter), the DHS side-plate acts as a short lever arm applying enormous bending forces at the plate-bone junction, leading to a very high implant failure rate (varus collapse, plate breakage). Subtrochanteric fractures require cephalomedullary nailing (e.g., Proximal Femoral Nail — PFN) which loads the femur centrally and resists bending forces through the intramedullary position.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.