Cadaver Demonstration and Surgical Techniques Summary

Cadaver Demonstration and Surgical Techniques

Initial Dissection and Observation

  • The initial process involves dissecting a cadaver foot, specifically focusing on the femur and TMT (Tarsometatarsal) joint.
  • The stiffness of the cadaver foot is noted, indicating it's less flexible than a live foot.
  • Surgical correction of a bunion is intended with the demonstrated procedure.

Surgical Guide Placement

  • The surgical guide is positioned on the foot, aligning with the metatarsal to correct declination.
  • The joint is marked, and a second pin entry point is marked 5mm behind the joint, creating a factory jawline.
  • The flat part of the guide aids in maintaining alignment along the metatarsal.
  • Wire placement is bicortical and distal.

Pin Insertion Technique

  • One pin is inserted into the dorsal medial aspect of the first metatarsal.
  • The distal end is held in place to avoid blackboarding (incorrect plantar flexion).
  • Adjustments are made due to the cadaver's limited pronation, creating pronation for demonstration.
  • Thumb screws are used to lock the toes and control sagittal plane movement by plantar flexing the metatarsal. Thumb screw number one locks over the first toe. Thumb screw number two locks over the second toe.
  • Thumb screw number four and three lock down after plantar flexion.

Adjustments and Corrections

  • Fine adjustments are made by compressing and repositioning the clamp.
  • Wires or Steinman pins may bend under excessive force, but the clamp remains intact.
  • Adjustments and corrections can be easily performed.

Model Rigidity and Simulation

  • The first TMT joint feels stiffer than in a live patient due to the absence of a proper joint.
  • The presenter suggests creating a simplified model for demonstration.
  • The metatarsal broke during the procedure, causing wire canting.

MIS (Minimally Invasive Surgery) Technique

  • Transition to MIS technique involves moving the pin to position three.
  • Wires are inserted vertically before making any cuts.
  • Thumb screws can be removed to provide more room when using a burr.
  • Sagittal plane is maintained using thumb screws.
  • Frontal plane adjustments are made before locking down the clamp.

Burr Usage

  • The burr is used with thumb screws to maintain the sagittal plane.
  • The clamp allows for readjustments and repositioning during the procedure.
  • Sagittal adjustments are fine-tuned and then tightened.

Wire Insertion and Stability

  • Wires are inserted using a blue-handled wire driver. Ensure straight vertical placement.
  • The device holds the correction with screws, freeing up the surgeon's hands.
  • The presenter prefers to hold the reduction manually but acknowledges this device's utility.

Device Utility and Marketability

  • The device is useful for those less familiar or comfortable with the technique and those who rely on jigs.
  • The device may offer better correction than manual methods, appealing to surgeons who need assistance.
  • It is particularly useful for surgeons who perform bunionectomies infrequently.

Cutting Head Prototype

  • Demonstration moves to a polycarbonate cutting head prototype on a saw bone.
  • The presenter observes the force required to use the device.
  • The old staple is used to create a seal.

Staple Insertion

  • Tapping is used for staple insertion, generally requiring minimal force (approximately 40 decibels).
  • Force applied should be comfortable; excessive force is not necessary.
  • Barrels often slide in easily during the procedure.

Prototype Demonstration

  • The arc of the prototype is demonstrated by Dr. Wrigley.
  • The presenter has switched to MIS for about 10% of their procedures.
  • A green line on the device aids in aligning the body with the point of resection.

Device Alignment and Usage

  • The device is aligned smoothly with the joint and positioned over the cuneiform for oblique cuts.
  • Prototype thumb screws are not as smooth as the final product will be.
  • Angulations on the device indicate the intermetatatarsal angle (IMA).
  • Hashtag markers help align subsequent cuts.

Wire Placement and Visualization

  • An Olivier wire is inserted through a hole in the device to visualize the resection plane.
  • The wire helps dial in the amount of resection needed.
  • Three-hole options ensure contact with the cuneiform.
  • The device holds the position while the cut is made.

Cutting and Repositioning

  • The device is moved distally to cut the base of the first metatarsal.
  • Rotation to approximately 15 degrees sets the angle for the cut, perpendicular to the long axis of the first metatarsal.
  • A wire is inserted to freeze the position.

Chevron Cut Simulation

  • The device simulates a chevron cut, allowing the toe to be cut off.
  • Cuts should sit parallel to each other.
  • A relative clamp can be used to hold everything together, followed by fixation.

Simultaneous Use of Devices

  • Simultaneous use of the clamp and cutting guide may be possible, particularly on smaller feet.
  • Separate left and right versions of the device will be available.
  • Adjustments can be made based on pre-op measurements, accommodating slight variations.

Radiopaque Indicators

  • Radiopaque lines on the device allow for X-ray verification of alignment.
  • A radiopaque extension can be added to ensure parallelism with the metatarsal.

MIS Chevron Osteotomy

  • The discussion shifts to the marketability of MIS Chevron osteotomy.
  • It allows for a smaller (one-centimeter) incision, appealing to surgeons who perform open procedures.
  • The Chevron jig facilitates accurate cuts through a small incision.

Device Features and Adjustments

  • The device provides a pre-trajectory screw for added stability.
  • Gray cannulas hold the guide in place, while a clear cuff protects the surrounding tissue.
  • Thumb screws allow the guide to sit off the foot in cases of a large bunion eminence, creating a tripod effect.

Micro Adjustments

  • Ratcheting thumb screws allow micro adjustments by sliding the device off-center and using one of the other gatling gun-like holes around the perimeter.
  • A targeting guide and K-wire are used for precise placement in the center of the met head.
  • This allows for micro-adjustments.
  • A cannulated guide can be used to perform a Chevron osteotomy, aiding in apex alignment.