Citations

Abstract Myopericytomas belong to a benign group of tumors consisting of perivascular myopericytes or pericytes with a characteristic myoid differentiation pattern. The tumor is histologically and radiographically heterogenous, similar to superficial myofibromas. We report on a case of a myopericytoma arising in the hypothenar eminence of a 58-year-old man with a history of over 15 years of ulnar-sided and midcarpal wrist pain. Decision was made to excise the mass after it had increased in size by over 50 % over a 10-year period. Excision of the mass led to remarkable relief of his symptoms in the hypothenar as well as midcarpal regions. Consideration of this rare perivascular tumor should be included in patients with slow-growing benign appearing masses within the subcutaneous tissues of the hand.

The purpose of this study was to evaluate the effect of wrapping bioabsorbable nerve conduit around primary suture repair on motor nerve regeneration in a rat model. Forty rats were randomly divided into two experimental groups according to the type of repair of the rat sciatic nerve: group I had primary suture repair; group II had primary suture repair and bioabsorbable collagen nerve conduit (NeuraGen® 1.5 mm, Integra LifeSciences Corp., Plainsboro, NJ) wrapped around the repair. At 12 weeks, no significant differences in the percentage of recovery between the two groups were observed with respect to compound muscle action potentials, isometric muscle force, and muscle weight (P = 0.816, P = 0.698, P = 0.861, respectively). Histomorphometric analysis as compared to the non‐operative sites was also not significantly different between the two groups in terms of number of myelinated axons, myelinated fiber area, and nerve fiber density (P = 0.368, P = 0.968, P = 0.071, respectively). Perineural scar tissue formation was greater in primary suture repair group (0.36 ± 0.15) than in primary repair plus conduit wrapping group (0.17 ± 0.08). This difference was statistically significant (P < 0.001). Wrapping bioabsorbable nerve conduit around primary nerve repair can decrease perineural scar tissue formation. Although the scar‐decreasing effect of bioabsorbable nerve wrap does not translate into better motor nerve recovery in this study, it might have an effect on the functional outcome in humans where scar formation is much more evident than in rats. © 2014 Wiley Periodicals, Inc. Microsurgery 34:562–567, 2014.

Object Choline acetyltransferase (ChAT) is an enzyme synthesized within the body of a motor neuron whose role is to form the neurotransmitter acetylcholine. Quantification of ChAT levels in motor or mixed nerves has been proposed to provide information regarding the viability of a proximal nerve stump for motor neurotization following brachial plexus injury. To do so requires information regarding normal ChAT levels and those in injured nerves, as well as the correlation of ChAT level determined at surgery with eventual motor recovery. The purpose of this study was to determine ChAT activity in the normal and injured sciatic/peroneal nerve in a rat model, evaluate the correlation between ChAT and motor recovery, find the relationship between ChAT activity and isometric muscle force, and elucidate the parallel between ChAT activity and acetylcholinesterase (AChE) activity. Methods Sixty animals were divided into 3 groups. The sciatic nerves in Group 1 were transected without repair. Nerves in Group 2 were transected and repaired. Nerves in Group 3 sustained a crush injury followed by transection and reconstruction. All animals were allowed 12 weeks of recovery followed by evaluation of ChAT levels in the peroneal nerve, correlated with measures of maximal isometric tibialis anterior muscle force and muscle weight (the operated side normalized to the control side). Karnovsky AChE staining of peroneal nerve segments was also compared with radiochemical assay of ChAT activity in the same nerve. Results A significant difference in the tibialis anterior isometric tetanic force and the tibialis anterior muscle weight index (TAMI) was noted between Group 1 and Groups 2 and 3 (p < 0.0001); no significant difference was found comparing Group 2 with Group 3. The correlation between the force measurement and the TAMI was 0.382. Both AChE measurement and ChAT activity demonstrated significantly fewer fibers in the operated nerve compared with the contralateral nerve. Intergroup variability could also be illustrated using these tests. The correlation coefficient between the isometric tetanic force measurement and the ChAT analysis in Groups 1 and 2 was 0.468. The correlation for the AChE staining and the isometric tetanic force measurement was 0.111. The correlation between the TAMI and the ChAT levels was 0.773. The correlation between the TAMI and the AChE-stained fibers was 0.640. Correlating AChE staining to the ChAT analysis produced a correlation of 0.712. Conclusions The great variability in all groups and weak correlations to the functional muscle assessments and the ChAT radiochemical assay made this technique an unreliable method of determining motor nerve viability.

The purpose of this study is to evaluate the rate of union after four-corner arthrodesis with a locking, dorsal circular plate comprised of polyether-ether-ketone. A retrospective review was conducted of all patients who underwent four-corner arthrodesis with a locking, dorsal circular plate at our institution from January 2005 to May 2009. The primary outcome measure was radiographic and clinical union. During the study period, 26 consecutive wrists underwent four-corner arthrodesis with a locking, dorsal circular plate. Twenty-three wrists were included. The mean clinical follow-up was 16 months (range 3–37). Union was achieved in 22 of 23 wrists at a mean time of 3 months (range 1–12). There was one partial union that underwent successful revision arthrodesis. In summary, four-corner fusion with a polyether-ether-ketone locking, dorsal circular plate results in high union rates. The use of a radiolucent plate allows for more accurate assessment of union with the biomechanical advantages of a fixed angle construct.