Arthroscopic-assisted percutaneous reduction and screw fixation of displaced scaphoid fractures.

Many scaphoid fractures can be treated with percutaneous screw insertion, but fracture displacement usually necessitates open reduction. Two surgeons treated 20 consecutive patients with displaced fractures of the scaphoid using arthroscopic-assisted percutaneous screw fixation. Thirteen patients had dorsal (antegrade) and seven had palmar (retrograde) percutaneous screw insertion. At an average follow-up of 18 (range 6-48) months, all of the fractures were healed and there were no implant problems. The early results of arthroscopic-assisted percutaneous screw fixation of displaced fractures of the scaphoid suggest that union can be obtained and good to excellent function achieved predictably without the need for open exposure. Avoidance of an open exposure limits wrist ligament injury and may preserve blood supply. Further evaluation of this procedure is merited.

Effects of long-term fixation on histological quality of undecalcified murine bones embedded in methylmethacrylate.

While long-term fixation and storage of specimens is common and useful for many research projects, it is particularly important for space flight investigations where samples may not be returned to Earth for several months (International Space Station) or years (manned mission to Mars). We examined two critical challenges of space flight experimentation: the effect of long-term fixation on the quality of mouse bone preservation and the preservation of antigens and enzymes for both histochemical and immunohistochemical analyses, and how the animal/sample processing affects the preservation. We show that long-term fixation minimally affects standard histological staining, but that enzyme histochemistry and immunolabeling are greatly compromised. Further, we demonstrate that whole animal preservation is not as suitable as whole leg or stripped leg preservation for long-term fixation and all histological analyses. Overall, we recommend whole leg processing for long-term storage of bone specimens in fixative prior to embedding in plastic for histological examination.

Results of nerve transfer techniques for restoration of shoulder and elbow function in the context of a meta-analysis of the English literature.

We report the results of 15 patients who underwent nerve transfer for restoration of shoulder and elbow function at our institution for traumatic brachial plexus palsy. We present these results in the context of a meta-analysis of the English literature, designed to quantitatively assess the efficacy of individual nerve transfers for restoration of elbow and shoulder function in a large number of patients. One thousand eighty-eight nerve transfers from 27 studies met the inclusion criteria of the analysis. Seventy-two percent of direct intercostal to musculocutaneous transfers (without interposition nerve grafts) achieved biceps strength > or =M3 versus 47% using interposition grafts. Direct intercostal transfers to the musculocutaneous nerve had a better ability to achieve > or =M4 elbow strength than transfers from the spinal accessory nerve (41% vs 29%). The suprascapular nerve fared significantly better than the axillary nerve in obtaining > or =M3 shoulder abduction (92% vs 69%). At our institution 90% of intercostal to musculocutaneous transfers (n = 10) achieved > or =M3 bicep strength and 70% achieved > or =M4 strength. Four of seven patients achieved > or =M3 shoulder abduction with a single nerve transfer and 6 of 7 regained > or =M3 strength with a dual nerve transfer. This study suggests that interposition nerve grafts should be avoided when possible when performing nerve transfers. Better results for restoration of elbow flexion have been attained with intercostal to musculocutaneous transfers than with spinal accessory nerve transfers and spinal accessory to suprascapular transfers appear to have the best outcomes for return of shoulder abduction. We conclude that nerve transfer is an effective means to restore elbow and shoulder function in brachial plexus paralysis.

Effect of suture locking and suture caliber on fatigue strength of flexor tendon repairs.

The objectives of this cadaveric study were 2-fold: to determine the effect of different locking configurations on the cyclical fatigue strength of flexor tendon repairs and to assess the differences between each repair when a 3-0 or 4-0 suture is used. One hundred twenty flexor digitorum profundus tendons were cut and repaired using nonlocked, simple locked, and cross-stitch locked variations of 2- and 4-strand flexor tendon repairs. Using an incremental cyclical loading protocol we performed 10 trials of each repair with both 3-0 and 4-0 sutures and analyzed the number of Newton-cycles to failure using a 3-way ANOVA. The use of a 3-0 suture led to a 2- to 3-fold increase in fatigue strength in all repairs tested and the fatigue strength of the 4-strand repairs was significantly greater than the 2-strand repairs. All repairs performed with 4-0 suture failed by suture rupture. Of the 3-0 suture repairs, the three 2-strand repairs and the 4-strand cross-stitch locked repair failed by suture rupture. In contrast, 6 of 10 of the 4-strand simple locked and nonlocked repairs failed by suture pullout. There was no significant difference in fatigue strength between the 2 locked and the nonlocked 2-strand repairs using either 3-0 or 4-0 suture. There also was no significant difference in holding capacity or fatigue strength between the simple locked or nonlocked 4-strand repairs. However, the 4-strand cross-stitch locked repair with a 3-0 suture had significantly improved fatigue strength and holding capacity compared with the other repairs tested. Based on the consistently inferior biomechanical performance of 4-0 suture, we recommend that 3-0 suture be considered for 2- or 4-strand tendon repairs when early active motion is planned. The orientation of the transverse and longitudinal components of simple locked repairs did not significantly influence their holding capacity or fatigue strength. The cross-stitch type of locked repair provides better holding capacity and fatigue strength compared with simple locked or nonlocked 4-stranded flexor tendon repairs.

Bacterial growth in space flight: logistic growth curve parameters for Escherichia coli and Bacillus subtilis.

Previous investigations have reported that bacterial suspension cultures grow to higher stationary concentrations in space flight than on Earth; however, none of these investigations included extensive ground controls under varied inertial conditions. This study includes extensive controls and cell-growth data taken at several times during lag phase, log phase, and stationary phase of Escherichia coli and Bacillus subtilis. The Marquardt-Levenberg, least-squares fitting algorithm was used to calculate kinetic growth parameters from the logistic bacterial growth equations for space-flight and control growth curves. Space-flight cultures grew to higher stationary-phase concentrations and had shorter lag-phase durations. Also, evidence was found for increased exponential growth rate in space.

Selection of small-colony variants of Enterobacteriaceae by in vitro exposure to aminoglycosides: pathogenicity for experimental animals.

Small-colony variants of gram-negative genera of Enterobacteriaceae were selected by in vitro exposure to gentamicin. These variants were shown to have decreased susceptibility in vitro to aminoglycosides. They were lethal for mice following intraperitoneal injection, with the LD50 (50% lethal dose) being the same as, or slightly less than, that for the parent organism. Variants of strain no. 2401 of Proteus mirabilis caused urinary tract infection in mice after implantation into their bladders. Although the variants grew somewhat less rapidly than did parent organisms, both parent and variant colonies alkalinized urine at the same rate. Electron microscopic study showed no differences between colonies of parents and variants. These studies indicated that small-colony variants of Enterobacteriaceae are pathogenic for experimental animals. Further, they may cause disease in humans and should not necessarily be regarded as only laboratory curiosities.