Mal alignment of the hip, knee, and ankle leads to premature cartilage damage and to development of degenerative arthritis of knee joint. Femoral and tibial osteotomies around the knee are established procedures for the restoration of the physiological load distribution of pressure at the knee joint. Accurate preoperative planning is mandatory to avoid under correction or overcorrection of axes or placing the joint-line in obliquity that ends to insufficient postoperative alignment.The majority of osteotomies are still planned and performed using conventional techniques drawing over transparent papers, cumbersome measurements etc.
The app assists at preoperative correction planning by calculating :
-the amount of correction preoperatively by calculating the dimension of wedge size , the correction angle and osteotomy gap opening or closing.
-mechanical axis deviation (in mm) MAD, anatomical and mechanical femoral axes angle (aMFA),mechanical lateral proximal femoral angle (mLPFA), mechanical lateral distal femoral angle(mLDFA), joint line convergence angle (JLCA),mechanical medial proximal tibial angle (mMPTA), Mechanical lateral distal tibial angle (mLDTA), Hip Knee Ankle line (HKA) ,Mid joint line (MJL) orientation.
-objectively the deviation or deformity in the frontal plane (varus or valgus) and differentiate the level of deformity (femoral and or tibial origin) and according to measured angles objectively suggest where indicated, medial or lateral, open or closed-wedge distal femur osteotomy or high-tibial osteotomy or double osteotomies and avoiding unwanted obliquity of the joint line
App allows he surgeon to
-change the planned mechanical axis to pass at the preferred percentage (Fujisawa point) after evaluation of the residual cartilage thickness left on the involved compartment.
select the location of hinge point of correction osteotomy for planning of varus or valgus corrections
-evaluate in real time the success of intended osteotomy by evaluating the kinematic alignment of the knee (KAO), avoiding residual joint obliquity or malalignment.
-measure the correction angle adjusted due to ligament instability and preoperatively calculate the height of osteotomy gap opening.
-pressing + or - button, one degree of correction is added or subtracted respectively and the second plane of osteotomy emerges and printed in screen real offering real time simulation of the wedge osteotomy in an instant to comprehend in real time what parameters are affected and modify favourably the correction angle. All above mentioned angles and all limp axes are redrawn and updated accordingly for the given new correction angle. The drawn schematic gives the impression of settings act as a whole interchangable interacting unit.
- dynamicaly preview and easily predict potential intraoperative errors, that could emerge and choose the optimal degree of correction without disruption kinematic alignment of the limp.
-to combine correction- Biplanar-, at coronal plane and sagittal plane (based on Hernigou 2001 calculations ) on tibia slope and provide the direction of the plane (ω angle) in which the osteotomy (open or closed) should be made ,the height the opening or closing wedge and the correction angle (Δ angle),
-to simulate, before real bone cuts are done and try different strategies in relation to the location, the type of osteotomy, the joint obliquity without to redraw in paper board countless drawings in an effort to achieve the optimal correction and mean while taking into account and balancing all influencing preoperative factors.
-real time dynamically change of mechanical axis lines, modify also the drawings of femur and the tibia and in instant depicting a precise preview of the whole preoperative plan for optimal results.
-categorisation of the deformities based to international literature normal references values, help to indicate to user the type of osteotomy.