The Safety of Volar to Dorsal Percutaneous Screw Fixation of Bennett Fracture-Dislocation - A Cadaveric Study.

Background: Bennett fractures are traditionally fixed with percutaneous K-wires from dorsal to volar, or with a volar to dorsal screw via a volar open approach. While volar to dorsal screw fixation is biomechanically advantageous, an open approach requires extensive soft tissue dissection, thus increasing morbidity. This study aims to investigate the practicality and safety of Bennett fracture fixation using a percutaneous, volar to dorsal screw, particularly with regard to the median nerve and its motor branch during wire and screw insertion. Methods: Fifteen fresh frozen forearm and hand specimens were obtained from the University of Auckland human cadaver laboratory. A guidewire is placed under image intensifier from volar to dorsal with the thumb held in traction, abduction and pronation. The wire is passed through the skin volarly under image intensifier, then the median nerve is dissected from the carpal tunnel and the motor branch of the median nerve (MBMN) is dissected from its origin to where it supplies the thenar musculature. The distance between the K-wire to the MBMN is measured. Results: In 14 of 15 specimens, the wire was superficial and radial to the carpal tunnel. The mean distance to the origin of the MBMN is 6.2 mm (95% CI 4.1-8.3) with the closest specimen 1 mm away. The mean closest distance the wire gets to any part of the MBMN is 3.7 mm (95% CI 1.6-5.8); in two specimens, the wire was through the MBMN. Conclusions: Wire placement, although done under image intensifier, is subject to significant variation in exiting location. While research has shown the thenar portal in arthroscopic thumb surgery is safe, our guidewire needs to exit further ulnar to capture the Bennett fracture fragment, placing the MBMN at risk. This cadaveric study has demonstrated the proposed technique is unsafe for use.

Opioid Prescription Usage after Benign Gynecologic Surgery: A Prospective Cohort Study.

STUDY OBJECTIVE: To compare the amount of opioids (tablets and morphine milligram equivalents [MMEs]) prescribed by physicians and used by patients after benign gynecologic surgery. DESIGN: Prospective cohort study. SETTING: Tertiary center: main hospital operating room and outpatient surgery center. PATIENTS: Women undergoing benign gynecologic surgery. INTERVENTIONS: Major and minor gynecologic surgeries. MEASUREMENTS AND MAIN RESULTS: The surgery groups were minor laparoscopy (Minor), major minimally invasive (Major), and laparotomy (Laparotomy). Demographic, medical, and surgical data were abstracted from electronic medical records. On postoperative day (POD) 7, women completed a telephone survey describing pain levels, prescription use, and satisfaction with pain control. Patients who continued to use opioids for pain relief were surveyed on POD 14. If use continued, patients were surveyed again on POD 28. The primary outcome was amount of opioid prescribed compared with opioid used. Of 193 screened participants 172 were enrolled (89%), and data were analyzed for 154 (90%): 59 (38%) Major, 71 (56%) Minor, and 24 (16%) Laparotomy. The median number of tablets and MMEs prescribed was lowest for the Minor group (Minor, 24 tablets; Major, 30 tablets; Laparotomy, 30 tablets [p <.01]; Minor, 150 MMEs; Major, 225 MMEs; Laparotomy, 225 MMEs [p = .01]). We found no difference in the number of tablets (Minor, 8; Major, 8; Laparotomy, 9; p = .77) or MMEs used (Minor, 45 MMEs; Major, 45 MMEs; Laparotomy, 55 MME; p = .81) between the groups. On POD 7 there was no difference in median numerical rating scale pain scores (Minor, 3; Major, 2; Laparotomy, 2; p = .07) or satisfaction with analgesia on POD 7 (p = .44), 14 (p = .87), and 28 (p = .18). Patients with prior chronic pain used more total amounts of opioids (68 MME vs 30 MME, p <.01) and were more likely to require opioid refill (odds ratio, 10.4; 95% confidence interval, 1.3-83.6) compared with those without a similar history. CONCLUSION: In this cohort, gynecologic surgeons prescribed nearly 3 times more opioid tablets and MMEs than was used by patients despite patients reporting similar levels of pain after minor and major surgeries.

Wound Infiltration With Extended-Release Versus Short-Acting Bupivacaine Before Laparoscopic Hysterectomy: A Randomized Controlled Trial.

STUDY OBJECTIVE: To evaluate if preincision infiltration with extended-release liposomal bupivacaine provides improved overall pain relief compared with 0.25% bupivacaine after laparoscopic or robotic-assisted hysterectomy. DESIGN: A single-center double-masked randomized controlled trial (Canadian Task Force Classification I). SETTING: A tertiary-care community hospital. PATIENTS: Patients recruited from July 2015 through January 2016. Sixty-four patients were randomized, and 59 were analyzed for the primary outcome. INTERVENTIONS: Women scheduled to undergo multiport laparoscopic or robotic-assisted total hysterectomy for benign indications were randomized to receive preincision infiltration with undiluted liposomal bupivacaine or 0.25% bupivacaine. MEASUREMENTS AND MAIN RESULTS: The primary outcome was overall average pain intensity by numeric rating scale (0-10) using the Brief Pain Inventory (BPI) via telephone survey on postoperative day (POD) 3. A sample size of 28 per group (N = 56) was planned to detect a 30% change in pain scores. Secondary outcomes were overall average and worst numeric pain scores on PODs 1, 2, and 14; pain scores in hospital; BPI pain interference scores; and total opioid use. There were no demographic differences between the 2 groups. For the primary outcome, we found a decrease in the average (p = .02) pain scores on POD 3 in the liposomal bupivacaine group. We also found a decrease in worst pain scores on POD 2 (p = .03) and POD 3 (p = .01). There were no differences in pain scores while in the hospital or on POD 1 or POD 14. There were no differences in BPI pain interference scores, opioid use, or reported adverse effects. CONCLUSION: For laparoscopic and robotic-assisted multiport hysterectomies, there is evidence of decreased average postoperative pain with liposomal bupivacaine compared with 0.25% bupivacaine for port-site analgesia on POD 3, but no difference in opioid use or measures of functioning.

Magnetic microbead transport during resistive pulse sensing.

Tunable resistive pulse sensing (TRPS) experiments have been used to quantitatively study the motion of 1 µm superparamagnetic beads in a variable magnetic field. Closed-form theory has been developed to interpret the experiments, incorporating six particle transport mechanisms which depend on particle position in and near a conical pore. For our experiments, calculations indicate that pressure-driven flow dominates electrophoresis and magnetism by a factor of ∼100 in the narrowest part of the pore, but that magnetic force should dominate further than ∼1 mm from the membrane. As expected, the observed resistive pulse rate falls as the magnet is moved closer to the pore, while the increase in pulse duration suggests that trajectories in the half space adjacent to the pore opening are important. Aggregation was not observed, consistent with the high hydrodynamic shear near the pore constriction and the high magnetization of aggregates. The theoretical approach is also used to calculate the relative importance of transport mechanisms over a range of geometries and experimental conditions extending well beyond our own experiments. TRPS is emerging as a versatile form of resistive pulse sensing, while magnetic beads are widely used in biotechnology and sensing applications.