UNASSIGNED: Peripheral nerve injury is a recognized complication after reverse shoulder arthroplasty (RSA) that has mainly been studied at the level of the brachial plexus and its proximal branches. However, the impact of RSA on distal peripheral nerves and the influence of elbow and wrist position is not known. This cadaveric study aimed to analyze the effect of RSA implantation and upper limb position on tension in the distal median and radial nerves. The hypothesis was that RSA increased distal nerve tension, which could be further affected by elbow and wrist position.
UNASSIGNED: 12 upper limbs in 9 full fresh-frozen cadavers were dissected. Nerve tension was measured in the median nerve at the level of the proximal arm, elbow, and distal forearm, and in the radial nerve at the level of the elbow, using a customized three-point tensiometer. Measurements were carried out before and after RSA implantation, using a semi-inlay implant (Medacta, Castel San Pietro, Switzerland). Two different configurations were tested, using the smallest and largest available implant sizes. Three upper-limb key positions were considered (plexus at risk, plexus relief, and neutral), from which the effect of elbow and wrist position was further tested.
UNASSIGNED: RSA implantation significantly increased median and radial nerve tension throughout the upper limb. The distal nerve segments were particularly dependent on elbow and wrist position. The plexus at risk position induced the most tension in all nerve segments, especially with the large implant configuration. On the other hand, the plexus relief position induced the least amount of tension. Flexing the elbow was the most efficient way to decrease nerve tension in all tested nerve segments and key positions. Wrist flexion significantly decreased nerve tension in the median nerve, whereas wrist extension decreased tension in the radial nerve.
UNASSIGNED: RSA significantly increases tension in the median and radial nerves and makes them more susceptible to wrist and elbow positioning. The mechanism behind distal peripheral neuropathy after RSA may thus result from increased compression of tensioned nerves against anatomical fulcrums rather than nerve elongation alone. Elbow flexion was the most effective way to decrease nerve tension, while elbow extension should be avoided when implanting the humeral component. Further studies are needed to assess the ulnar nerve.

OBJECTIVE: Although there are some studies reporting the benefits of using laser to improve wound closure, there were a few studies in a model of oral mucosa. The aim of this in vitro study was to compare immediate tensile strength of the wound closure between suture alone and suture combined with CO2 laser welding.
METHODS: The study was conducted in 40 samples of the tissue blocks from ventral sides of pig tongues. A 20 mm-length and 5 mm-depth incision was made in each sample. The samples were randomly allocated into 2 groups namely: the control group and the experimental group. The samples of the control group were sutured with 3- stitch of 4-0 black silk. The samples of the experimental group were irradiated with CO2 laser (ultrapulse mode, 800 Watt peak power, 10 Hz, 0.2 ms pulse duration and 2,262.62 J/cm(2) energy density) before sutured. The immediate tensile strength of the wound was measured by using customized tensiometer under stereomicroscope.
RESULTS: The median of tensile strength of the control group and the experimental group were 30.40 g/cm(2) and 40.50 g/cm(2), respectively. There was no statistically significant difference between the groups (P value = 0.58). The proportions of the samples without wound dehiscence at the maximum limit of the tensiometer (120 g/cm(2)) were 0.15 (3/20) in the control group and 0.35 (7/20) in the experimental group.
CONCLUSIONS: The CO2 laser welding used in this study failed to show a greater immediate tensile strength but had a higher proportion of the wound without dehiscence at the 120 g/cm(2) tensile strength by comparison with the suture alone.