Minimally invasive total knee arthroplasty surgery through navigated freehand bone cutting: winner of the 2005 "HAP" PAUL AWARD.

Navigated freehand bone cutting (NFC) is introduced as a concept to eliminate alignment jigs and facilitate smaller arthroplasty incisions. We compare experimental cuts with this technique to conventional jigs. Using an in-house-built computer-aided orthopedic surgery system directly navigating a bone saw, users with different levels of surgical skills were timed performing full sets of distal femoral total knee arthroplasty cuts with jigs and with NFC. The cut surfaces were digitized to measure roughness and 3-dimensional translational/rotational errors. Navigated freehand cutting was 15% faster and produced 200% rougher surfaces than jigs, although its worst peaks/valleys were less than 1.2 mm. Implant fit/looseness, assessed by special navigated tools, was similar; but alignment was 400% better with NFC. Even at its infancy, NFC appears not to prohibitively compromise time and quality of cutting. Without requiring jigs, it has potential for radically less invasive total knee arthroplasty surgery.