Biomechanical Effects of Hindfoot Alignment in Supination External Rotation Malleolar Fractures: A Human Cadaveric...

Area of Science:

• Orthopedic biomechanics
• Ankle fracture analysis
• Human cadaveric studies

Background:

• Ankle joint pressure distribution is influenced by hindfoot alignment.
• Supination external rotation (SER) ankle fractures are common injuries.
• Understanding the effect of hindfoot alignment on SER fractures is crucial for treatment.

Purpose of the Study:

• To evaluate how hindfoot alignment affects ankle joint contact pressures in SER fractures.
• To analyze changes in pressure distribution, contact area, and center of force under different hindfoot alignments.
• To correlate radiographic parameters with biomechanical changes in SER fractures.

Main Methods:

• Created SER fractures in 10 human cadaver lower extremities, simulating progressive injury stages.
• Simulated varus and valgus hindfoot alignment by displacing the calcaneal tuberosity.
• Applied axial load and measured center of force, contact area, and peak contact pressure.

Main Results:

• Valgus hindfoot alignment with deep deltoid ligament disruption (step 3) significantly altered center of force and contact area.
• No significant changes in peak pressure were observed in either varus or valgus alignment.
• Medial clear space widened and talar tilt increased significantly in valgus alignment with deep deltoid disruption.

Conclusions:

• SER-IV fractures with valgus hindfoot alignment exhibit significant changes in pressure distribution and radiographic parameters compared to varus alignment.
• Deep deltoid ligament integrity is vital for maintaining normal ankle joint contact stress in valgus hindfoot alignment.
• Treatment decisions for SER fractures should consider hindfoot alignment and deltoid ligament status.