Two versus 3 lag screws for fixation of long oblique proximal phalanx fractures of the fingers: a cadaver study.

PURPOSE: To compare 2- versus 3-screw fixation for oblique fractures of the proximal phalanx in a cadaver model that simulates active finger motion. METHODS: We experimentally cut the proximal phalanges of the index, middle, and ring fingers of 9 cadaveric hands. Five fingers were assigned to a control group with no fixation, and 22 were fixed with either 2 or 3 lag screws. One digit was excluded because of iatrogenic fracture during preparation. The fingers were fitted with a differential variable reluctance transducer that measured maximum interfragment displacement while the fingers were subjected to 2,000 full flexion and extension cycles to simulate a 6-week active motion protocol. RESULTS: Analysis of variance revealed a significant difference between the control group and both the 2- and the 3-screw group. The 2- and 3-screw group average displacements were not significantly different. Both of these groups were equivalent with a power of 90%. CONCLUSIONS: Biomechanical stability during simulated active motion protocol did not differ in simulated proximal phalanx fractures treated with 2 lag screws or 3. CLINICAL RELEVANCE: Fracture fixation using 2 screws may be more cost and time effective and, therefore, more attractive to the surgeon, even when 3 screws can be placed. Furthermore, surgeons may consider using 2 screws rather than resorting to plate fixation when 3-screw fixation is not possible for these types of fractures.

Zygomaticomaxillary complex fractures and their association with naso-orbito-ethmoid fractures: a 5-year review.

BACKGROUND: Zygomaticomaxillary complex fractures associated with ipsilateral naso-orbito-ethmoidal fractures are more complex injuries than isolated zygomaticomaxillary complex fractures. This injury pattern can have significant long-term morbidity if not recognized and treated appropriately during the initial operation. The purpose of this study is to compare mechanisms of injury, treatment, and outcome between patients with zygomaticomaxillary complex fractures and those with zygomaticomaxillary complex and ipsilateral naso-orbito-ethmoidal fractures. METHODS: A 5-year retrospective review of all patients treated with zygomaticomaxillary complex fractures at a level I trauma center was performed. Computed tomographic scans were reviewed to divide patients into those with zygomaticomaxillary complex fractures alone and those with zygomaticomaxillary complex and ipsilateral naso-orbito-ethmoidal fractures. Demographics, treatment protocols, outcomes, complications, reoperations, and length of follow-up were identified for both groups and compared to determine differences between these populations. RESULTS: A total of 245 patients were identified by the Current Procedural Terminology codes for zygomaticomaxillary complex fractures. One hundred eighty-five patients had zygomaticomaxillary complex fractures and 60 patients had zygomaticomaxillary complex/naso-orbito-ethmoidal injuries. The demographics for both populations were similar. There are differences between the groups with regard to mechanism of injury, operative findings, and techniques. The patients with zygomaticomaxillary complex/naso-orbito-ethmoidal fractures had higher rates of postoperative complications and deformities. CONCLUSIONS: Patients who sustain a zygomaticomaxillary complex fracture associated with an ipsilateral naso-orbito-ethmoidal fracture have a higher incidence of postoperative complications and deformities. It is important to recognize this fracture pattern early to help minimize postoperative morbidity. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.

Biomechanics and histology of intact and repaired digital nerves: an in vitro study.

PURPOSE: To investigate the biomechanical properties of intact and repaired cadaver digital nerves. METHODS: Ultimate tensile failure strength and stiffness were determined in 67 human cadaver digital nerves. Total nerve area, fascicular area, and nonfascicular (connective tissue) area were determined from the metacarpophalangeal to the distal interphalangeal joint in another 35 axial nerve sections to determine regional anatomic variation. Thirty-eight additional digital nerves were transected, and epineural repairs were performed using simple, interrupted sutures. Suture number (2 vs 4), gauge (8-0 vs 9-0), and purchase length (1 mm vs 2 mm) were used in various combinations, and then the repaired nerves were pulled to failure. The mechanism of repair-site failure was determined for each suture. In situ tension of the intact digital nerves was measured during passive metacarpophalangeal and proximal interphalangeal joint motion in another 19 intact digital nerves. RESULTS: There were no significant differences in failure load or stiffness with respect to the radial or ulnar nerves within a finger or between fingers. The primary tactile side of the finger tended to have a larger diameter digital nerve. Digital nerve failure was more common proximally than distally. Intact digital nerves failed at 6 N with a stiffness of 1 N/mm. Histologic analysis showed that fascicular area and total area decreased from proximal to distal, whereas the nonfascicular-to-fascicular area ratio increased. Four epineural sutures were statistically stronger than 2 sutures. Suture purchase length and gauge did not affect repair strength. The 8-0 nylon sutures failed primarily by cut-out, whereas the 9-0 sutures failed by cut-out or breakage. Repaired nerves failed at 1 to 2 N. Maximal metacarpophalangeal joint hyperextension resulted in 4 N of digital nerve tension. When the metacarpophalangeal joint was not hyperextended, proximal interphalangeal joint motion did not generate tension. CONCLUSIONS: Similar to flexor tendons, the number of suture strands crossing the repair site was the most important variable affecting digital nerve repair strength in this cadaveric model.

Biscyclization reactions in butadiyne- and ethyne-linked triazenes and diazenes: concerted versus stepwise coarctate cyclizations.

A series of alkyne-linked bis-2H-indazoles has been prepared by the double cyclization of ethyne- or butadiyne-linked phenyltriazene or phenyldiazene moieties. Even though there are two five-membered ring cyclizations and several triple bond shifts involved, the reactions proceed rapidly under neutral conditions with mild heating, affording the heterocycles in excellent yields. DFT calculations, in agreement with experimental observations, indicate that the reactions: (1) occur via a very short-lived carbene intermediate, (2) are concerted via an asymmetrical transition state, or (3) are even synchronous, with as many as 16 bonds that are made or broken simultaneously. The biscyclizations presented herein strikingly illustrate the concept of coarctate reactions, the stabilization of transition states by coarctate Möbius aromaticity, the ethynologation principle, and the stereochemical rules.