The biomechanical efficacy of an oscillating K-wire driver.

A new oscillating drill, designed for insertional ease and safety, was biomechanically tested using an MTS 812 servohydraulic material testing machine (Instrom). Holding strength and drilling force were compared against a traditional rotary drill using rabbit tibias to approximate the diameter and cortical thickness of human metacarpals. Three differently sized (0.028-, 0.045-, and 0.062-in. diameter) K-wires were evaluated for each drill. Mean peak axial load (drilling force) was significantly different for each wire driver type in each of the three sized K-wires (p < or = 0.01). The oscillating drill used an average of 3 N less force to penetrate either cortex. Mean peak pull-out force (holding strength) was higher for the oscillating drill, but the difference was not significant (p > or = 0.5). This study indicated that the oscillating drill required less force for insertion and had a similar holding strength as the rotary drill. In addition, our drill has been shown to be less damaging to surrounding soft tissues. This new type of drill is likely to be advantageous in the fields of hand, microsurgery, orthopedic, and plastic surgery, where bone fixation is often near vital neurovascular structures.

Evaluation of a temporary arteriovenous shunt to establish neovascularization in a musculocutaneous flap: an experimental study.

On the dorsum of adult Sprague-Dawley rats, 3 x 7 cm pedicle flaps were raised and a temporary arteriovenous shunt (AVS) from anastomosis of the tail artery and vein was placed beneath. Fourteen, 21 and 28 days later, the pedicle flaps were converted to island flaps leaving only the AVS attachment. The degree of subsequent flap viability was directly related to the amount of time before flap conversion. At 14, 21 and 28 day intervals, there was 33.4%, 73.5% and 98% flap viability, respectively. Long-term AVS patency was found not to be required for flap survival. Normal hair growth, quantity and quality, occurred in only the 28 day delay group. Microangiography and histologic examination revealed extensive neovascularization from both the AVS artery and vein extending into the muscle, subcutaneous tissue and skin layers of each island flap. In summary, neovascularization of a large random pattern musculocutaneous island flap is possible using a temporary arteriovenous shunt. Flap survival is directly related to the length of time between AVS placement and cutaneous pedicle division, although long-term AVS patency is not required for continued flap viability. Hair growth may directly reflect the degree of underlying neovascular maturation. This AVS neovascularization technique could be applied to create new donor sites for free tissue transfer.