Quantitative biomechanical comparison of ankle fracture casting methods

Area of Science:

• Orthopedics
• Biomechanics
• Biomaterials

Background:

• Ankle fractures are rising in aging populations, often requiring conservative treatment due to circulation issues.
• Standard casts (SC) have limitations including malunion and skin complications, necessitating improved casting systems.
• Biomechanical stability requirements for ankle fracture casting are not well-defined.

Purpose of the Study:

• To quantitatively assess the biomechanical stability of a novel close contact cast (CCC) system.
• To compare the torsional stability of CCC against standard casts (SC) in simulated ankle fractures.
• To evaluate the impact of simulated tissue swelling on the stability of both CCC and SC.

Main Methods:

• Two adult mannequin legs were stabilized with either CCC or SC by an experienced surgeon.
• One mannequin leg incorporated an inflatable model simulating distal tissue swelling.
• Cyclic torsional loading was applied to measure rotation angle and torque, assessing cast stiffness and stability.

Main Results:

• The CCC system demonstrated stiffness equal to or greater than SC in two measures of torsional resistance.
• The reduction in ankle site stability due to simulated swelling resolution was significantly more pronounced in CCC compared to SC.
• CCC provided comparable biomechanical stability to SC under tested conditions.

Conclusions:

• The close contact cast (CCC) system offers biomechanical stability similar to standard casts (SC) for ankle fractures.
• CCC is a viable alternative for conservative ankle fracture management, particularly in older patients.
• Frequent re-application of CCC may be necessary to maintain stability as post-injury swelling subsides.