Valgus stability of the elbow

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Elbow Joint Anatomy

Background:

• Elbow valgus stabilizers are known anatomically but their quantitative importance is unclear.
• Understanding the contribution of specific structures is crucial for elbow injury management and surgical reconstruction.

Purpose of the Study:

• To quantify the acute changes in elbow valgus stability after sequential disruption of key stabilizing structures.
• To determine the relative contributions of the medial collateral ligament (anterior and posterior portions) and the radial head to valgus stability.

Main Methods:

• Load-displacement testing was performed on 30 cadaver elbow specimens.
• Testing was conducted in three flexion positions (0, 45, 90 degrees) under valgus stress.
• Stability was assessed after sequential sectioning of the posterior medial collateral ligament, radial head excision, radial head replacement, and anterior medial collateral ligament sectioning.

Main Results:

• The anterior portion of the medial collateral ligament was identified as the primary stabilizer against valgus stress.
• Excision of the radial head alone resulted in a significant average decrease of 30% in the slope of the torque-displacement curve.
• Silicone radial head replacement did not significantly restore stability after radial head excision.

Conclusions:

• The anterior medial collateral ligament plays a critical role in maintaining elbow valgus stability.
• The radial head is a significant contributor to elbow stability, and its excision leads to substantial instability.
• Current silicone radial head prostheses provide limited benefit in restoring valgus stability post-excision.