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. 2024 Apr 23;16(4):100068.
doi: 10.1016/j.jham.2024.100068. eCollection 2024 Oct.

Assessment of ulnar nerve tension directed towards understanding cubital tunnel syndrome

J Bauknight  1 , H A Shah  1 , C Fouad  1 , P J Schimoler  1   2 , M C Miller  1   2 , W Yetter  1 , P Tang  1
Affiliations

Assessment of ulnar nerve tension directed towards understanding cubital tunnel syndrome

J Bauknight et al. J Hand Microsurg. .

Abstract

Background: Ulnar nerve compression at the elbow is the second most common compressive neuropathy of the upper extremity. We hypothesize that tension on the ulnar nerve produced by elbow flexion and distraction contributes to this condition. We measured ulnar nerve tension generated during elbow flexion and proportional distraction to evaluate locations of soft tissue constraints to nerve translation.

Methods: Eight fresh-frozen upper limb specimens were tested. Each specimen included the proximal humeral shaft to the wrist. The ulnar nerve was dissected proximally and clamped to the humerus 8 ​cm proximal to the medial epicondyle. At 8 ​cm distal to the medial epicondyle, the ulnar nerve was dissected and clamped distally to a load cell that was mounted on a laboratory stand. A stage on the stand could be translated distally to apply load. Soft tissue was removed distal to the load cell clamp; all soft tissue from the load cell to the proximal humeral clamp was left intact.We measured the tension generated on the nerve throughout the full arc of elbow flexion with additional distal distractions of 0%, 2.5% and 5% of nerve length applied by distal translation of the stage on the lab stand. We then repeated these steps with the nerve unclamped proximally. We then excised 1 ​cm of soft tissue distally, clamped the nerve 7 ​cm distal to the medial epicondyle, and repeated the measurements. We continued this sequential dissection and testing until the nerve was clamped to the load cell 1 ​cm distal to the medial epicondyle.

Results: Flexion, distraction, and proximal clamping each increased nerve tension. Tension was greatest at 4, 5, and 6 ​cm distal to the medial epicondyle (p ​< ​0.01).

Conclusion: Flexion, distraction, and proximal clamping each increased ulnar nerve tension. The greatest ulnar nerve tension was recorded between 4 and 6 ​cm distal to the medial epicondyle.

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Conflict of interest statement

The Authors declare that there is no conflict of interest

Figures

Fig. 1
Fig. 1
Labeled side view of mounted left elbow specimen in the testing fixture. The humerus is to the left and the radius and ulna are to the right.
Fig. 2
Fig. 2
Labeled overhead view of left elbow mounted in testing fixture with nerve clamped proximally to the yellow clamp (left side of picture) and distally to the silver clamp (right side of picture).
Fig. 3
Fig. 3
Ulnar nerve tension as a function of distance to the medial epicondyle, elbow flexion angle, and applied strain.
See this image and copyright information in PMC

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