Finite Element Analysis Of The Biomechanics Of The Patellofemoral Joint After Medial High Tibial Biplanar Osteotomy(ascending Osteotomy And Descending Osteotomy)

Objective: To investigate the biomechanical changes of the patellofemoral joint after two types of medial tibial high biplanar osteotomies using a three-dimensional finite element method to provide some reference for clinical work.Methods: A healthy male,27 years old,was randomly recruited,and CT(computed tomography)and MRI(magnetic resonance imaging)scans of the left knee were completed,and a finite element model of the inversion deformity(inversion 7°)of the knee joint was established using ABAQUS version 2020 software.The corresponding patellofemoral joint pressures and stresses on the patella and femur were measured at 15°,30°,45°,60°,75°,90°,105°,and 120° angles,and the changes in patellar height were also measured under different force distributions during the osteotomy correction process of the two osteotomies.Results: In our experiment,the knee joint was corrected to 62.5% of the lower extremity force line through the tibial plateau after surgery,and we could see that the two types of osteotomy(ascending osteotomy and descending osteotomy)had some effects on the biomechanics of the patellofemoral joint after surgery,and the patellofemoral joint pressure,patellofemoral and femoral stresses were changed at different knee flexion angles.After ascending osteotomy,the pressure on the patellofemoral joint was the lowest at 90° of knee flexion,and the highest at 120° of knee flexion,with a 4.41-fold increase in pressure,while after descending osteotomy,the femur produced the least stress at 90° of knee flexion and the greatest stress at 15° of knee flexion,with an increase in pressure of approximately 3.34 times.After ascending osteotomy,the femur produced the least stress at 90° of knee flexion and the greatest stress at 105° of knee flexion,with an increase in pressure of approximately 12.35 times,while after descending osteotomy,the femur produced the least stress at 90° of knee flexion and the greatest stress at 120° of knee flexion,with an increase in pressure of approximately 10.65 times.After ascending osteotomy,the patella produced the least stress at 90° of knee flexion and the greatest stress at 15° of knee flexion,with an increase in pressure of about 1.42 times,while after descending osteotomy,the patella produced the least stress at 120° of knee flexion and the greatest stress at 15° of knee flexion,with an increase in pressure of about 1.50 times.Meanwhile,the patellar height was basically unchanged after ascending osteotomy,which had less effect,while the patellar height decreased after descending osteotomy,which might have produced a low patella.Conclusions: The biomechanics of the patellofemoral joint is affected after both biplanar osteotomies.After surgery,the biomechanics of the patellofemoral joint changes with the change of knee flexion angle,and the stress on the femur changes more and is more sensitive;compared with the descending osteotomy,the stress on the patellofemoral joint pressure,patella and femur at each angle of knee flexion is smaller after ascending osteotomy;there is no significant effect on patellar height after ascending osteotomy In contrast,patellar height decrease after descending osteotomy.