Is initial interfragmentary compression made to last? An ovine bone in vitro study

Area of Science:

• Orthopedic biomechanics
• Surgical fixation principles
• Bone fracture healing research

Background:

• Interfragmentary compression is crucial for fracture healing but difficult to quantify clinically.
• Compression may be lost rapidly, even without functional loading, impacting treatment outcomes.
• Understanding fixation methods' ability to maintain compression is vital for surgical success.

Purpose of the Study:

• To experimentally quantify and compare interfragmentary compression maintenance.
• To test if lag screws or compression plates provide similar initial compression.
• To evaluate if neutralization locking plates reduce compression loss compared to compression plates.

Main Methods:

• Ovine femora and humeri underwent osteotomies (oblique or transverse).
• Fixation used either a lag screw with a neutralization locking compression plate (LCP) or a dynamic compression plate (LCP).
• Interfragmentary pressure and fragment displacements were recorded for one hour.

Main Results:

• Both fixation methods provided initial compression, with no significant difference in compression loss over one hour (0.52% vs. 0.17%).
• Rotational and axial displacements were minimal in both groups.
• Measured compression forces (~100 N) are vulnerable to physiological loading.

Conclusions:

• Lag screws with neutralization plates and compression plates effectively maintain interfragmentary compression in ovine models for the first hour.
• Both methods are suitable for oblique (lag screw/neutralization plate) and transverse (compression plate) fractures.
• Achieving absolute stability may require additional fixation methods due to physiological loading.