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Cubital tunnel syndrome is the second most common nerve entrapment neuropathy. When non-operative treatments fail, surgical intervention is indicated. Although there remains no consensus between simple decompression and anterior transposition, there is a growing recognition of improved clinical outcomes in the latter. Few details of ulnar nerve branches around the elbow are available however and their sacrifice may be necessary to facilitate anterior transposition. Therefore, ten cadaveric upper extremities were dissected to delineate the course and branching pattern of the ulnar nerve around the elbow joint; anterior transposition was also performed in the cadaveric specimens. Digital photographs of the dissection study were analyzed using the Image J package. Results show that distal ulnar nerve branches are distributed more laterally towards the olecranon and may potentially restrict transposition more than has been recognized; proximal branches may also overlap incision lines of such transposition procedures.

Biomechanical evaluation of the subsynovial connective tissue (SSCT) provides insight into the causes of carpal tunnel syndrome. Studies of carpal tunnel mechanics have been performed using fresh-frozen cadaver tissue. Freezing can affect mechanical properties of some tissues, but its effect on SSCT is unknown. A total of 16 rabbit paws were harvested from eight New Zealand rabbits and subjected to mechanical testing consisting of three repeated tendon excursions in sets of three different excursion magnitudes. One paw from each animal was unfrozen. The contralateral paw was frozen and thawed before testing. Force, energy and stiffness of the first cycle of each set were evaluated, as were ratios of the second to first cycle for each parameter. Two-factor ANOVA with repeated measures over both factors was performed. No significant interactions between factors were found. There were no significant differences between fresh and frozen paws for any parameters, though there were significant differences between excursion amplitudes. The damage threshold was not different between fresh and frozen paws. This study demonstrated that freezing rabbit subsynovial connective tissue does not significantly change its mechanical properties. The same may be true for human cadaver tissues. Results of cadaver mechanical testing may not be influenced by this preservation technique.

Background: This study aimed to investigate whether the distance between the radial nerve and rotational center of the elbow joint when observing from the lateral surface of the humerus changes according to passive elbow joint flexion for safe external fixation with a hinged fixator of the elbow joint.

Methods: Twenty fresh-frozen cadaveric arms were dissected. The points where the radial nerve crosses over the posterior aspect of the humerus, crosses through the lateral center, and crosses over the anterior aspect of the humerus were defined in the lateral view of the elbow joint, using fluoroscopy, as R1, R2, and R3, respectively. The distances between the rotational center and each point on the radial nerve were measured when the flexion angle of the elbow joint was 10°, 50°, 90°, and 130°.

Results: The distances between the rotational center and R1, R2, and R3 were 118 mm, 94 mm, and 65 mm, respectively, when the flexion angle was 10°; 112 mm, 93 mm, and 74 mm, respectively, for 50°; 108 mm, 93 mm, and 77 mm, respectively, for 90°; and 103 mm, 94 mm, and 83 mm, respectively, for 130°. The distance between the rotational center and R2 was constant regardless of the flexion angle. With elbow joint extension, the distances between R1 and R3 increased; the safe zone, a region where the radial nerve would not be located on the humerus, was the smallest in extension. When the elbow joint was flexed, the distances between R1 and R3 decreased; the safe zone was the largest in flexion.

Conclusions: This study showed that the radial nerve location on the humerus varied based on the flexion angle of the elbow joint; the safe zone may change. A half-pin can be likely inserted safely, avoiding the elbow joint extension position.

Background: The purpose of the present study was to assess the biomechanical strength and properties of a modified Krackow technique for side-to-side tendon repair with a short overlap length.

Methods: The flexor digitorum superficialis, flexor digitorum profundus, and flexor pollicis longus muscles were harvested from 10 fresh frozen cadavers. Overall, 60 tendon repairs were divided into four groups based on the suture technique: modified Krackow technique repair (KT); weave suture repair (WS); mattress suture repair (MS); and composite technique repair (CT), a combination of the modified Krackow and weave suture techniques. Single loading mechanical tests were performed, and the results for each suture technique were compared.

Results: Ultimate loads for KT, WS, MS, and CT were 155 ± 45 N, 122 ± 18 N, 92 ± 31 N, and 163 ± 22 N, respectively. KT and CT had significantly higher ultimate loads than the other groups. However, the difference between the KT and CT groups in terms of ultimate load was not significant.

Conclusions: Based on the results from the single loading tests, the use of the modified Krackow and composite techniques appeared to provide stronger fixation than that with the use of the weave and mattress sutures with a short overlap length.

Background: Bennett fractures are traditionally fixed with percutaneous K-wires from dorsal to volar, or with a volar to dorsal screw via a volar open approach. While volar to dorsal screw fixation is biomechanically advantageous, an open approach requires extensive soft tissue dissection, thus increasing morbidity. This study aims to investigate the practicality and safety of Bennett fracture fixation using a percutaneous, volar to dorsal screw, particularly with regard to the median nerve and its motor branch during wire and screw insertion.

Methods: Fifteen fresh frozen forearm and hand specimens were obtained from the University of Auckland human cadaver laboratory. A guidewire is placed under image intensifier from volar to dorsal with the thumb held in traction, abduction and pronation. The wire is passed through the skin volarly under image intensifier, then the median nerve is dissected from the carpal tunnel and the motor branch of the median nerve (MBMN) is dissected from its origin to where it supplies the thenar musculature. The distance between the K-wire to the MBMN is measured.

Results: In 14 of 15 specimens, the wire was superficial and radial to the carpal tunnel. The mean distance to the origin of the MBMN is 6.2 mm (95% CI 4.1–8.3) with the closest specimen 1 mm away. The mean closest distance the wire gets to any part of the MBMN is 3.7 mm (95% CI 1.6–5.8); in two specimens, the wire was through the MBMN.

Conclusions: Wire placement, although done under image intensifier, is subject to significant variation in exiting location. While research has shown the thenar portal in arthroscopic thumb surgery is safe, our guidewire needs to exit further ulnar to capture the Bennett fracture fragment, placing the MBMN at risk. This cadaveric study has demonstrated the proposed technique is unsafe for use.