Management of neglected Bennett fracture in manual laborers by tension fixation.

PURPOSE: To report the results of open reduction and internal fixation (ORIF) of Bennett fractures in young, active patients using a K-wire and wire loop construct to achieve anatomical reduction and to allow return to manual labor. METHODS: In this prospective series, we treated 10 male manual laborers (mean age, 30 y; range, 20-44 y) with Bennett fractures diagnosed after a minimum of 12 weeks (mean, 16 wk; range, 12-18 wk). ORIF using 2 K-wires with a wire loop and a neutralizing transarticular K-wire was performed with direct articular visualization. Patients were evaluated for range of motion, grip strength, and pinch strength, and a visual analog scale score rated pain before surgery and 12 months later. RESULTS: The mean follow-up was 16 months (range, 12-36 mo). The average visual analog scale improved from 6 to 2, mean palmar abduction improved from 15° to 40°, mean radial abduction increased from 22° to 39°, average pinch strength improved from 9.9 kg to 15.5 kg, and average grip strength increased from 34 kg to 49 kg. Complications included transient irritation of the radial sensory nerve or lateral cutaneous nerve of the forearm in 3 patients, pin track granuloma formation in 2 patients, and marginal osteophyte formation in 2 patients. Union was achieved in all 10 patients, and 9 patients returned to their previous manual labor occupation. CONCLUSIONS: Our results suggest that neglected Bennett fractures can be effectively managed by ORIF using K-wires and a wire loop without compromising strength or motion. This technique reliably restored the anatomy and provided adequate thumb motion and strength to allow a return to manual labor. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Nerve physiology: mechanisms of injury and recovery.

Peripheral nerve injuries are common conditions, with broad-ranging groups of symptoms depending on the severity and nerves involved. Although much knowledge exists on the mechanisms of injury and regeneration, reliable treatments that ensure full functional recovery are scarce. This review aims to summarize various ways these injuries are classified in light of decades of research on peripheral nerve injury and regeneration.

The rapidly evolving centromere-specific histone has stringent functional requirements in Arabidopsis thaliana.

Centromeres control chromosome inheritance in eukaryotes, yet their DNA structure and primary sequence are hypervariable. Most animals and plants have megabases of tandem repeats at their centromeres, unlike yeast with unique centromere sequences. Centromere function requires the centromere-specific histone CENH3 (CENP-A in human), which replaces histone H3 in centromeric nucleosomes. CENH3 evolves rapidly, particularly in its N-terminal tail domain. A portion of the CENH3 histone-fold domain, the CENP-A targeting domain (CATD), has been previously shown to confer kinetochore localization and centromere function when swapped into human H3. Furthermore, CENP-A in human cells can be functionally replaced by CENH3 from distantly related organisms including Saccharomyces cerevisiae. We have used cenh3-1 (a null mutant in Arabidopsis thaliana) to replace endogenous CENH3 with GFP-tagged variants. A H3.3 tail domain-CENH3 histone-fold domain chimera rescued viability of cenh3-1, but CENH3's lacking a tail domain were nonfunctional. In contrast to human results, H3 containing the A. thaliana CATD cannot complement cenh3-1. GFP-CENH3 from the sister species A. arenosa functionally replaces A. thaliana CENH3. GFP-CENH3 from the close relative Brassica rapa was targeted to centromeres, but did not complement cenh3-1, indicating that kinetochore localization and centromere function can be uncoupled. We conclude that CENH3 function in A. thaliana, an organism with large tandem repeat centromeres, has stringent requirements for functional complementation in mitosis.