Maintenance of Compression With a Positional Screw Versus Compression Generated With a Lag Screw

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Bone fracture healing

Background:

• Achieving and maintaining interfragmentary compression is crucial for optimal bone fracture healing.
• Reduction clamps provide initial compression, but their long-term effectiveness and the role of adjunctive fixation require further investigation.

Purpose of the Study:

• To evaluate if a position screw can maintain reduction clamp-induced interfragmentary compression in cortical bone fractures.
• To compare the compressive force generated by a position screw with that of a lag screw (LS).

Main Methods:

• Oblique fractures were created in composite cortical bone models.
• Interfragmentary compression was measured using in-fracture force sensors after reduction with a clamp.
• Compression was assessed with clamp alone, clamp plus position screw, and position screw alone, and subsequently with lag screw fixation.

Main Results:

• A reduction clamp generated an average initial compression of 139.77 N.
• Lag screw (LS) fixation significantly increased interfragmentary compression (P = 0.01).
• Position screws decreased compression, and their removal further reduced fracture compression (P = 0.013).

Conclusions:

• Reduction clamps provide initial interfragmentary compression.
• Lag screws (LS) significantly enhance fracture compression.
• Position screws are ineffective at maintaining compression and actively reduce it.