Ultrasound imaging has been used for performing single-injection peripheral nerve blocks and continuous catheters. One limitation with current technology is the inability to confirm the location of the needle or catheter tip. We describe a new needle and catheter design that permits distal tip visualization using color flow Doppler. An 18-gauge 100-mm insulated Tuohy needle and a 20-gauge 50-mm polyamide catheter (open tip) with a Teflon-coated steel stylet (B. Braun, Bethlehem, PA) were customized by adhering in place two piezoelectric actuators. These created 1-8 kHz vibrations when coupled to a function generator (FG502, Tektronix, Richardson, TX) and a 100 W audio amplifier (R3000, KLH, Sun Valley, CA). Mimicking a lateral popliteal fossa block, the needle and catheter were inserted into the leg of an unembalmed cadaver. When activated, the tip of each was highlighted in color when scanned in the short axis using the color Doppler mode of a two-dimensional ultrasound and a 12 MHz L38 probe (MicroMaxx, Sonosite, Bothell, WA). Vibration technology may be a useful adjunct while performing ultrasound-guided regional anesthesia. Further study evaluating its usefulness and safety in live tissue is warranted.
Robust biologic ingrowth of tendon into a porous tantalum implant surface can be achieved under conditions of secure initial mechanical fixation. The strength and stiffness of the tendon-implant construct reached normal levels by six to twelve weeks in this animal model.
Freiberg's infraction is a condition of cartilage degeneration of the lesser metatarsal heads. Adolescent females are the "textbook" patients but both males and females may present with this condition later in life. The second and third metatarsals are the most commonly affected, while involvement of the fourth and fifth is rare. The incidence is higher in females than in males. The pathophysiology is unknown, but studies suggest a combination of vascular compromise, genetic predisposition, and altered biomechanics. Diagnosis is made clinically and imaging is used to confirm. Early in the process, radiographs are normal however bone scans may demonstrate a photopenic center with a hyperactive collar and magnetic resonance imaging can reveal hypointensity of the metatarsal head. As Freiberg's infraction progresses, radiographs show a flattened and fragmented metatarsal head. Nonoperative treatment is based on decreasing foot pressure and unloading the affected metatarsal. Spontaneous healing with remodeling may occur in early stages of the disease. Operative options are dorsal closing wedge osteotomies, osteochondral transplant, and resection arthroplasty. Currently, we do not understand this disease sufficiently to prevent its occurrence. Outcomes of nonoperative and operative management are good to excellent and most patients are able to return to previous activity.
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