Intramedullary Threaded Nail Fixation Versus Plate and Screw Construct in Metacarpal Neck Fractures: A Biomechanical...

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Hand surgery

Background:

• Surgical management of metacarpal neck fractures lacks a superior fixation technique.
• Current options include Kirschner wires, plates, intramedullary fixation, and headless screws.
• This study compares intramedullary threaded nail (ITN) fixation with locking plate constructs.

Purpose of the Study:

• To compare the biomechanical stability of intramedullary threaded nail (ITN) fixation versus locking plate fixation for metacarpal neck fractures.
• To evaluate the load-to-failure characteristics of these two fixation methods.

Main Methods:

• Cadaveric index and small finger metacarpals were fractured at the neck.
• Samples were randomly assigned to ITN fixation (n=8) or 2.3-mm locking plate fixation (n=6).
• Biomechanical testing was performed to determine ultimate load to failure for both intact and stabilized specimens.

Main Results:

• Both ITN and locking plate fixation provided stabilization but were significantly weaker than intact metacarpals.
• ITN fixation demonstrated a statistically higher load to failure compared to locking plate fixation (p=0.039).

Conclusions:

• Intramedullary threaded nail (ITN) fixation provides superior biomechanical strength for vertically oriented metacarpal neck fractures compared to locking plate fixation.
• While both fixation methods stabilize fractures, neither restores the strength of native bone.