Cubital tunnel syndrome is the most prevalent neuropathy of the ulnar nerve and its aetiology is controversial. Potential replacement materials should display similar viscoelastic properties. The purpose of this study was to assess the feasibility and merit of quantifying the frequency-dependent viscoelastic properties of proximal and distal sections of the human ulnar nerve. Four ulnar nerves (n = 4) were dissected from the elbows of human cadavers and sectioned at the level of the cubital tunnel into proximal and distal sections. These eight sections of the ulnar nerve were sinusoidally loaded to induce stresses between 0.05-0.27 MPa and the viscoelastic properties were measured between 0.5-24 Hz using Dynamic Mechanical Analysis. The nerves were found to exhibit frequency-dependent viscoelastic behaviour throughout this frequency range. The median storage moduli of the proximal nerves ranged between 7.03 and 8.18 MPa, and 8.85 to 10.19 MPa for distal nerves, over the frequency-sweep tested. The median loss moduli of the proximal nerves ranged between 0.46 and 0.81 MPa and between 0.51-0.80 MPa for distal nerves. Ulnar nerves display frequency dependency viscoelasticity. Such characterisation is feasible with potential applications to suitable nerve grafts.

The primary aim was to determine whether a dynamic suture marker method of measuring ulnar nerve strain yields comparable results to strain gauges. The secondary aim was to assess the effect of elbow flexion, shoulder abduction and medial epicondylectomy on strain. Methods: In four embalmed elbows, ulnar nerve strain was measured using suture markers during elbow flexion and shoulder abduction before and after medial epicondylectomy. Linear regression analysis and Wilcoxon signed-rank test were used to analyse the results. Results: Ulnar nerve strain increased in direct proportion to elbow flexion angle before and after medial epicondylectomy, with one exception. At 90° shoulder abduction, strain was 0%-17%. Strain was greatest at 90° and least at 110° before and after medial epicondylectomy, P > 0.05. The effect of medial epicondylectomy varied. Strain was reduced at 90° by 5%, at 110° by 0% and at 120° by 1%; P > 0.05. Conclusions: The suture marker method yielded comparable results to strain gauges. Both shoulder abduction and medial epicondylectomy did not have statistically significant effects on ulnar nerve strain. However, only four embalmed elbows were studied in this preliminary study, so a large difference would be needed to produce a significant change. The finding that medial epicondylectomy fails to reduce strain raises questions about its role in treating cubital tunnel syndrome and highlights the need for further research. The authors believe that the technique described for dynamic strain assessment is applicable in an in vivo setting and therefore, should be used to compare strain properties of cadaveric and in vivo nerves.

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The aim of this study was to develop a finite element model to investigate the forces on tendons which ensue due to trigger finger. The model was used to simulate both flexor and extensor tendons within the index finger; two test cases were defined, simulating a “mildly” and “severely” affected tendon by applying constraints. The finger was simulated in three different directions: extension, abduction and hyper-extension. There was increased tension during hyper-extension, with tension in the mildly affected tendon increasing from 1.54 to 2.67 N. Furthermore, there was a consistent relationship between force and displacement, with a substantial change in the gradient of the force when the constraints of the condition were applied for all movements. The intention of this study is that the simulation framework is used to enable the in silico development of novel prosthetic devices to aid with treatment of trigger finger, given that, currently, the non-surgical first line of treatment is a splint.