Postoperative pain score does not correlate with injury severity in isolated tibial plateau fractures.

PURPOSE: Appropriate management of acute postoperative pain is critical for patient care and practice management. The purpose of this study was to determine whether postoperative pain score correlates with injury severity in tibial plateau fractures. METHODS: A retrospective review of prospectively collected data was completed at a single academic level one trauma center. All adult patients treated operatively for tibial plateau fractures who did not have concomitant injuries, previous injury to the ipsilateral tibia or knee joint, compartment syndrome, inadequate follow-up, or perioperative regional anesthesia were included (n = 88). The patients were split into groups based on the AO/OTA fracture classification (B-type vs C-type), energy mechanism, number of surgical approaches, need for temporizing external fixation, and operative time as a proxy for injury severity. The primary outcome measure was the visual analog scale (VAS) pain score (average in the first 24 h, highest in the first 24 h, two- and six-week postoperative appointments). Psychosocial and comorbid factors that may affect pain were studied and controlled for (history of diabetes, neuropathy, anxiety, depression, PTSD, and previous opioid prescription). Additionally, opioid use in the postoperative period was studied and controlled for (morphine milligram equivalents (MME) administered in the first 24 h, discharge MME/day, total discharge MME, and opioid refills). RESULTS: VAS scores were similar between groups at each time point except the two-week postoperative time point. At the two-week postoperative time point, the absolute difference between the groups was 1.3. The groups were significantly different in several injury and surgical variables as expected, but were similar in all demographic, comorbid, and postoperative opioid factors. CONCLUSIONS: There was no clinical difference in postoperative pain between AO/OTA 41B and 41C tibial plateau fractures. This supports the idea of providers uncoupling nociception and pain in postoperative patients. Providers should consider minimizing extended opioid use, even in more severe injuries.

Stiffening of Circumferential F-Actin Bands Correlates With Regenerative Failure and May Act as a Biomechanical Brake in the Mammalian Inner Ear.

The loss of inner ear hair cells causes permanent hearing and balance deficits in humans and other mammals, but non-mammals recover after supporting cells (SCs) divide and replace hair cells. The proliferative capacity of mammalian SCs declines as exceptionally thick circumferential F-actin bands develop at their adherens junctions. We hypothesized that the reinforced junctions were limiting regenerative responses of mammalian SCs by impeding changes in cell shape and epithelial tension. Using micropipette aspiration and atomic force microscopy, we measured mechanical properties of utricles from mice and chickens. Our data show that the epithelial surface of the mouse utricle stiffens significantly during postnatal maturation. This stiffening correlates with and is dependent on the postnatal accumulation of F-actin and the cross-linker Alpha-Actinin-4 at SC-SC junctions. In chicken utricles, where SCs lack junctional reinforcement, the epithelial surface remains compliant. There, SCs undergo oriented cell divisions and their apical surfaces progressively elongate throughout development, consistent with anisotropic intraepithelial tension. In chicken utricles, inhibition of actomyosin contractility led to drastic SC shape change and epithelial buckling, but neither occurred in mouse utricles. These findings suggest that species differences in the capacity for hair cell regeneration may be attributable in part to the differences in the stiffness and contractility of the actin cytoskeletal elements that reinforce adherens junctions and participate in regulation of the cell cycle.