Fixation for metacarpal neck fracture: a biomechanical study

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Hand surgery

Background:

• Optimal surgical treatment for displaced, unstable metacarpal neck fractures lacks robust evidence.
• Current fixation methods include dorsal locking plates and K-wire fixation.
• A novel metacarpal sled fixation system was developed to enhance stability while minimizing dissection and hardware exposure.

Purpose of the Study:

• To compare the biomechanical stability of a new metacarpal sled fixation system against standard locking plate and K-wire fixation.
• To evaluate fixation integrity in a simulated porcine metacarpal fracture model.

Main Methods:

• Transverse metacarpal neck fractures were created in 30 porcine metacarpals.
• Specimens were randomly assigned to fixation with locking plates, metacarpal sleds, or retrograde K-wires.
• Constructs underwent biomechanical testing using three-point bending to determine load-to-failure, stiffness, and peak load.

Main Results:

• The K-wire group exhibited the highest initial stiffness, followed by the sled and then the plate groups (p<0.05 between K-wire and plate).
• The plate group demonstrated the highest peak load, followed by the sled and then the K-wire groups (p<0.05 between sled and plate, and K-wire and plate).
• No significant difference in peak load was found between the K-wire and sled groups.

Conclusions:

• The metacarpal sled construct provides fixation comparable to K-wires for transverse metacarpal neck fractures.
• The sled offers advantages of limited dissection and avoidance of exposed hardware.
• This low-profile, minimally invasive construct is a viable option for unstable metacarpal neck fractures.