2017 ISAKOS Biennial Congress ePoster #1523

 

Computer Supported Complex Osteotomy Procedures Around The Knee (CT Preoperative Planning, Navigation System, 3D Printing Technologies)

Bogdan Ambrozic, PhD, Ankaran SLOVENIA
Samo Novak, MD, Murska Sobota SLOVENIA

Valdoltra Orthopaedic Hospital, Ankaran, SLOVENIA

FDA Status Not Applicable

Summary

Computer Supported Complex Osteotomy Procedures Around The Knee

Abstract

The main aim of this paper is to show the surgical procedure of computer supported complex osteotomy around the knee.
Osteotomy for mono-compartment osteoarthritis of the knee is the most common indication for deformity correction surgery. In osteotomy treatment we have to identify source of malalignment, decide whether femoral and/or tibial osteotomy is needed. We have to define CORA (center of rotation of angulation) and choose the type of osteotomy, magnitude of correction and choose type of fixation. In cases of monocompartment osteoarthritis malalignment has single or multiple sources: tibial deformity, femoral deformity, condyle depressions, ligamentous laxity. If in varus malalignment there is mLDFA abnormality (>93°) with normal MPTA, femoral osteotomy is preferred. If MPTA is less than 85° and mLDFA is normal, tibial osteotomy is performed. If the mLDFA is slight in varus (<92°) and the MPTA is in the varus end of normal 85-87°), tibial osteotomy is preferred. If mLDFA and MPTA are in varus, combined osteotomy is indicated.
The daily practice on open or closed wedge osteotomy is based on two dimensional x-ray planning procedures, but we know that this approach cannot solve complex cases because the knee anatomy is three dimensional structure. First off all the open or closed wedge osteotomy planning in lower limb are mostly done in one plane which can be easy transfer into the surgical procedure.
In our surgical practice we used the navigation system GUIDING STAR from Ekliptik company with module TOCOS as control tool which shows that also simply angle correction in on plane can deform the angles in other two planes. We design new method to add accuracy in correcting deformity which is based on patient preoperative CT/MRI scan, 3D planning tool, plastic surgery guides and navigation control system. First the CT/MRI images of the knee are processed to reconstruct the 3D knee model. In the planning procedures we used EBS preoperative planning tool from Ekliptik Company to plan the osteotomy cut in all three planes. Based on cut angles and directions we make surgical plastic guides which are printed out from biocompatible plastic. To confirm the accuracy of designed plastic surgical guides we used navigation control system which allows us to have control in real time over the angles in all three planes.
The amount of correction should be equal to the amount of angular deformity at the CORA, plus the JLCA (joint line convergence angle), plus overcorrection amount. The best results were obtained when mechanical axis line was shifted through the Fugisaja point (62% on the lateral plateau region). In lateral compartment osteoarthritis the MAD should be corrected to neutral to not overload medial compartment.