Ulnar nerve excursion and strain at the elbow and wrist associated with upper extremity motion

Area of Science:

• Orthopedics
• Neuroscience
• Biomechanics

Background:

• Ulnar nerve excursion is critical for unimpeded upper extremity function.
• Common sites of ulnar nerve entrapment include the cubital tunnel and Guyon's canal.
• Understanding nerve movement is vital for diagnosing and treating neuropathies.

Purpose of the Study:

• To quantify the ulnar nerve excursion required for common daily activities.
• To assess the strain on the ulnar nerve during these motions.
• To investigate the relationship between limited excursion and nerve entrapment syndromes.

Main Methods:

• Utilized five fresh-frozen cadaver specimens (10 arms).
• Measured ulnar nerve excursion at the elbow and wrist using laser-guided calipers and a DVRT strain device.
• Correlated nerve excursion with shoulder, elbow, wrist, and finger movements measured by goniometer.

Main Results:

• An average of 4.9 mm (elbow) and 5.1 mm (elbow) excursion was needed for shoulder and elbow motion, respectively.
• 13.6 mm excursion was required at the wrist for wrist flexion/extension.
• Combined motions necessitated 21.9 mm (elbow) and 23.2 mm (wrist) excursion, with 15% strain occurring at specific joint movements.

Conclusions:

• Significant ulnar nerve excursion is necessary for normal upper extremity function.
• Factors limiting nerve mobility at the elbow and wrist may contribute to cubital tunnel syndrome and Guyon's canal neuropathy.
• Quantifying excursion and strain provides biomechanical insights into ulnar nerve pathologies.