Medical Devices : Surgical devices


Minimally Invasive Spinal Fusion

UW–Madison researchers have developed a method and surgical instrumentation to enable minimally invasive spinal fusion. In the procedure, a sharp pointed tube (a trocar) is inserted along the spine. Using the trocar as a guide, the bone graft material is pulled into place. The trocar is removed, releasing the graft in the desired location along the spine.

Minimally Invasive Microwave Ablation Antennas

UW–Madison researchers have developed two minimally invasive, balun-free antenna designs that are small enough to treat cancers otherwise out of the reach of microwave ablation.

The first design can take any base-fed monopole, spiral or bent wire configuration. Alternatively, the antenna can use a structure more suitable for higher frequencies (five GHz to 30 GHz). This design uses cable shielding over a balanced two-wire transmission line. The design protects surrounding tissue and eliminates the need for baluns.

Surgical Manipulator with Finer Motion Control and Capability

A UW–Madison researcher has developed a new device, called an interleaved continuum-rigid manipulator, that combines safety and high performance. The device is made of flexible segments interleaved with small, rigid-link joints. The segments elastically flex upon insertion into tissue, and are designed for tendon-driven articulation and telescoping motion. The rigid joints serve as limited stroke actuators to move and control the flexible segments.

Monitoring Tumor Ablation in Real Time

UW–Madison researchers have developed a method that uses radiofrequency signals transmitted from a microwave ablation probe to monitor the boundaries between a tumor, ablation zone and background healthy tissue.

The probe emits and then detects the signals as they echo off the different tissue boundaries. Since the boundary between a tumor and background tissue becomes less distinct as the ablation progresses, clinicians can determine when treatment is complete based on these echoes.

Portable Carbon Monoxide Source for Therapy and Organ Delivery

UW–Madison researchers have developed a portable carbon monoxide generator for medical use that creates precise, therapeutically relevant, concentrations of medical grade CO out of the surrounding air in real time. The device is inherently safe, as it produces only the amount of CO needed for therapy. The device is incapable of producing enough CO to pose a safety hazard.

The heart of the generator is a reaction chamber holding a small cartridge of purified carbon. The CO is produced by heating the carbon in the presence of air that is fed continuously into the reaction chamber. The carbon can be heated by any controllable energy source, such as an electrical filament or laser.

The amount of CO in the output stream is monitored by a sensor. Using feedback on both the gas flow rate and the heat source, the amount of CO generated is controlled to match the prescribed, adjustable value.

Calibrated Drill Sleeve Also Protects Soft Tissue

UW–Madison researchers have developed a separable drill sleeve that provides braking resistance and can be used with conventional orthopedic drills and bits. The sleeve protects soft tissue from the drill bit, measures the depth of the bore hole and prevents the drill from plunging through the far side of the bone.

The sleeve features upper and lower tube segments. At the lower end is a base that contacts bone and provides a passage for the drill bit. The upper segment is able to slide relative to the base and indicate bore depth. In between the segments is a fluid damper that resists sudden acceleration of the drill bit as it pushes beyond the bone.

Adjustable Implant for Treatment of Glottic Insufficiency

UW-Madison researchers have developed an inflatable, adjustable laryngeal implant for the treatment of glottic insufficiency. The implant utilizes an implantable balloon stabilized by a titanium frame. The titanium frame is implanted into the thyroid cartilage of the larynx to provide a mount for the implant and to prevent it from shifting into the airway. The adjustable implant is filled with saline, which pushes the paralyzed vocal fold closer to the functioning fold to restore vocal fold capabilities and alleviate breathing, swallowing and voicing issues. The balloon is filled through a port and valve configuration that also can be used to remove any excess saline, allowing for post-operative adjustment.

Fan-Beam Microwave Horn for Improved Organ Resection

UW-Madison researchers have developed a dielectric-filled microwave waveguide-fed horn antenna applicator for bloodless surgery and resection, especially resection of the liver.  The applicator is placed against the surface of the liver and microwave power is applied.  The horn antenna applicator radiates microwaves uniformly into the tissue, causing coagulation.  This design provides fast and efficient control of coagulation while allowing a bloodless resection area. 

The planar design of the horn antenna application is superior to small or cylindrical radiator sources in that it provides less attenuation and a more constant temperature range in the coagulation region.  The surface applicator also offers the user control because there is no need for imaging modalities such as ultrasound to confirm placement or coagulation.

Electrode Array for Radiofrequency Tissue Ablation

UW-Madison researchers have developed a faster method of bipolar RF ablation that uses an electrode array to heat tissue between electrodes. The electrodes are inserted into the tissue along a resection cut line. To heat the tissue, RF energy is applied in bipolar mode between pairs of probes set in a comb-like configuration. Power is switched between pairs of electrodes in half-second intervals, allowing all probes to heat the tissue, but avoiding increased impedance, which compromises effective heating.

Surgical Tool with Integrated Pressure and Flow Sensors

UW-Madison researchers have developed a surgical tool with an integrated pressure sensor that can be used to measure the pressure and flow of liquid being delivered to or removed from the surgical area. The surgical tool includes a needle-like portion that enters the tissue. The integrated sensor is coupled directly to a fluid flow channel in the tool, through which fluid may be injected into or drawn from a patient. The tool could be designed as a micromachined silicon tool with a fully integrated sensor formed from a silicon nitrate membrane and polysilicon resistors. Alternatively, the tool could be an ultrasonically actuated cutting tool.

Ultrasonically Actuated Needle Pump System

UW-Madison researchers have developed a needle pump system composed of two needles – an outer, stationary tubular needle having a penetrating tip and a hollow bore, and an inner tubular needle that is mounted in the bore of the outer needle. The dimensions of the device are only 1.6 cm by 1.5 cm. The inner needle is ultrasonically vibrated by an ultrasonic actuator without vibrating the outer needle.