Foot & ankle international
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The management of proximal fifth metatarsal ("Jones") fractures in athletes has become increasingly more aggressive, despite a lack of biomechanical data in the literature. A cadaver biomechanical study was conducted to evaluate the strength of intramedullary fixation of simulated Jones fractures loaded to failure via three-point bending on a Materials Testing System machine. In a series of eight intact fifth metatarsal control specimens, the force to failure (fracture) was measured for comparison with repaired specimens. ⋯ There was no statistical difference between the average forces at initial displacement or at complete displacement in the fixed metatarsal specimens for the two different types of screws, but the forces at complete displacement for each screw type were significantly greater than the forces at initial displacement (P < 0.05). On the basis of literature review and data generated from this study, it is apparent that the forces necessary to cause displacement of the stabilized Jones fracture are above what would be transmitted within the lateral midfoot during normal weightbearing. The choice of screw and intramedullary technique of fixation is a matter of surgeon preference, because the choice of screw makes no biomechanical difference.
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We investigated peroneal reaction time (PRT) of 18 patients (21 ankles) with functional instability of the ankle and 8 healthy volunteer controls (9 ankles) before and after injecting local anesthetic into the sinus tarsi. The median PRT in patients before the injection was 82.0 ms, a significant delay from 71.0 ms in controls. ⋯ A disorder of the gamma-muscle-spindle system, induced by proprioceptive deficit after damage to a ligament, has been advocated as a cause of prolonged PRT. We suggest that irritability of mechanoreceptors or nociceptors or both, induced by inflammation at the sinus tarsi, may suppress the activities of gamma motor neurons of peroneal muscles, which in turn might cause the symptoms of functional instability and prolonged PRT.
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Fifty consecutive patients, studied prospectively, underwent an elective first metatarsophalangeal joint arthrodesis or proximal metatarsal osteotomy and modified McBride bunionectomy, with or without concomitant lesser toe procedures. A field block was administered only at and distal to the level of the tarsometatarsal joints using 30 cc equal parts 0.25% bupivacaine and 1% lidocaine without epinephrine. Before injection, the monitoring anesthesiologist gave the patient intravenous (IV) sedation, usually an amnestic agent. ⋯ The average duration of the local block was 8 hr (range, 5-14 hr); none of the patients had recall of negative events, and overall patient satisfaction was 98%. Midfoot blocks are easy to administer and provide reliable anesthesia for reconstructive forefoot surgery. Monitored IV sedation enhances patient acceptance, facilitates block administration, and provides a valuable measure of patient safety and comfort.