1. Field of the Invention
The present invention generally relates to surgical instruments used for carpal tunnel release, and is particularly directed to an improved hub and handle design.
2. Background Description
MicroAire Surgical Instruments has been marketing for a number of years a surgical tool based on U.S. Pat. No. 4,962,770 to Agee et al., U.S. Pat. No. 4,963,147 to Agee et al., U.S. Pat. No. 5,089,000 to Agee et al., and U.S. Pat. No. 5,306,284 to Agee et al, each of which is incorporated fully herein by reference. This surgical tool is used to inspect and manipulate selected tissue in a body cavity, and has particular application to performing safe and effective carpal tunnel release. These tools include a handle assembly, a probe member, an optical system, and a cutting system. The optical system and cutting system extend through the handle and into the probe and permit a surgical blade to be selectively deployed and retracted from a lateral opening in the top surface of the probe at its distal end.
The preferred use of the surgical instrument in performing carpal tunnel release is accomplished by forming a short transverse incision located proximal to the carpal tunnel and the wrist flexion crease. After longitudinal spreading dissection, to avoid injury to the sensory nerves, the incision is continued through the deep fascia of the forearm, the distal extension of which leads to the flexor retinaculum. After an incision through the finger flexor synovium, extension of the wrist will then expose the proximal opening of the carpal tunnel, thereby forming a passage to the carpal tunnel. The rotational orientation of the probe relative to the handle or holder is adjustable to suit the needs of the surgeon. After adjusting the rotational orientation of the probe, the probe is inserted through the incision and desirably through the length of the carpal tunnel to the distal edge of the flexor retinaculum.
By employing the optical system, and through manipulation of the patient's extremities, the anatomy within the carpal tunnel can be clearly visualized on a display of a video monitor connected to a video camera and lighting source associated with the optical system. The distal end of probe will desirably have gently displaced the tendons, bursa and median nerve found within the carpal tunnel to facilitate insertion of the probe. Then the lateral aperture of the probe will be positioned adjacent the medial surface of the flexor retinaculum and, desirably, the configuration of the probe upper surface (which is preferably a flat surface) will exclude the displaced tissues from the region surrounding the lateral aperture. Markers can be used to indicate the point on the probe where the blade elevates, and help facilitate proper placement of the probe relative to the distal edge of the flexor retinaculum.
At the appropriate location, a cutting blade will be extended to contact the distal edge of the flexor retinaculum, while the surgeon views the tissue to be divided via the display. The blade point will desirably be extended to a position sufficient to completely release the ligament. While viewing (through the lateral aperture in the probe) the intended path of the extended cutting blade, the probe is then withdrawn, thereby dividing the flexor retinaculum and releasing the carpal tunnel.
The surgical tool described by Agee et al. is safe and effective and well regarded in the surgical community. Improvements to the mechanism for securely fastening the probe to the handle and for orienting the lateral opening of the probe to either side of the handle will be well regarded within the community. Currently, the tool includes a spring loaded knob and locking member which cooperates with an annular groove in the probe end. To align the probe to one side or another, the surgeon must align indicia or a rib member on the probe with indicia on the handle and screw the knob a sufficient amount to tighten the locking member against the probe