The ideal group to review this material would be Orthopedic Foot & Ankle Fellows and Senior Podiatric Surgical Residents. This demographic possesses the foundational anatomical knowledge required to understand the landmarks discussed but remains within the "learning curve" phase where the technical nuances of transitioning from freehand to guided MIS (Minimally Invasive Surgery) are most critical.
Abstract
This technical demonstration outlines a standardized protocol for performing a minimally invasive bunionectomy using the Arthrex guided system. Dr. Noman Siddiqui details the transition from inconsistent freehand methods to a guided approach designed to optimize rotation, translation, and fixation of the capital fragment. The presentation emphasizes preoperative preparation, including high-thigh draping and specific fluoroscopic positioning (declination of the first metatarsal) to ensure visualization of the first tarsometatarsal (TMT) joint. Key surgical steps highlighted include the use of a "gooseneck" intramedullary guide for automatic translation, the application of accessory wires for sagittal plane stabilization, and the importance of oscillating wire techniques to prevent cortical skiving. The procedure concludes with a dual-screw fixation strategy, utilizing parallel guides and non-compressive screws to maintain the achieved correction while avoiding osteotomy distraction.
Surgical Summary: Guided MIS Bunionectomy Protocol
0:00 System Overview and Learning Curve: The Arthrex MIS system replaces freehand techniques with a guided method to improve consistency in rotation and fixation. The guided approach reduces the surgical learning curve from 30–50 cases to approximately 15–20.
1:02 Positioning and Draping: Optimal exposure requires draping to the mid-thigh to allow unobstructed medial access for wire firing. A limb-holding device (e.g., Trumano) is recommended to free the surgeon’s hands for precise positioning.
2:01 Fluoroscopic Landmarks: To visualize the first TMT clearly, a wedge is placed under the fifth ray to elevate the foot, providing a slight declination of the first metatarsal relative to the 90° C-arm beam.
2:51 Pre-Incision Marking: Surgeons should mark the projected trajectory of the hardware and the anatomical axis of the first metatarsal. The primary incision is located between the first TMT and the naviculocuneiform (NC) joint to prevent hardware skiving.
4:46 Osteotomy Technique: The osteotomy is performed approximately 2.5 cm proximal to the MTP joint. The medial cortex is addressed first, followed by a lateral pilot hole. The burr must be directed toward the surgeon (rather than the ceiling) to maintain proper sagittal plane declination.
7:00 Translation and De-rotation: A "gooseneck" translational component is seated in the intramedullary canal to achieve an automatic 50% lateral shift. The surgeon manually supinates the hallux to de-rotate the capital fragment and realign the sesamoids before wire fixation.
9:47 Sagittal Plane Stabilization: An accessory guide wire is placed through the capital fragment into the second metatarsal. This "tack" prevents dorsal or plantar translation of the head during subsequent drilling and fixation.
10:46 Targeting Arm Application: The targeting guide is aligned with the proximal markings (just below the tibialis anterior tendon). It must be tightened securely while maintaining contact with the proximal landmarks to ensure the wire hits the capital fragment accurately.
13:47 Preventing Cortical Skiving: When advancing wires through the lateral cortex, the surgeon should use an oscillating maneuver rather than aggressive pushing. This allows the wire tip to cut the bone effectively without deflecting or skiving off the cortex.
16:18 Parallel Fixation: Following the initial proximal wire, a 25° or 30° parallel guide is used to place the second wire. This ensures both screws capture the capital fragment while maintaining the intermetatarsal (IM) angle correction.
19:25 Final Fixation and Seating: Non-compressive screws are used. The drill must be advanced slightly deeper than the screw length to prevent distraction at the osteotomy site. The screw bevel must be oriented toward the bone, verified by the marking on the driver handle.