[Finite element analysis of mechanical of acupotomy release on popliteus muscle for knee osteoarthritis]

To evaluate impact of needle-knife dissection of popliteus muscle on stress distribution of knee joint by establishing finite element models of knee joint before and after needle-knife intervention.

CT data from a patient (male, 42 years old, weighted 82 kg, the course of disease ranged from 15 months, left side, K-L gradeⅡ)with early-stage knee osteoarthritis (KOA) were used to construct a finite element model of knee joint by using Mimics 21.0, Geomagic 2021, SolidWorks 2021, and Ansys 2021R1. The distal tibia was fixed with complete constraints to simulate single-leg standing. A vertical downward force of 500 N was applied to the proximal femur, and 200 N upward force parallel to Q-angle was applied to quadriceps tendon. The knee joint was simulated at 30° and 90° flexion angles to compare stress distribution and magnitude changes in meniscus, femoral cartilage, and patellar cartilage before and after acupotomy intervention.

At 30° of knee flexion, the peak surface stresses of femoral cartilage, patellar cartilage, and meniscus in intervention group decreased by 5.910 MPa (31.23%), 0.441 MPa (2.05%), and 6.216 MPa(26.38%), respectively, compared with non-intervention group. At 90° of knee flexion, the corresponding decreases were 1.999 MPa (7.10%), 2.736 MPa (6.49%), and 4.671 MPa (10.51%), respectively. After acupotomy release, the area of stress distribution increased, and abnormal stress concentration was alleviated.

Acupotomy release of popliteus muscle effectively improves stress distribution on tibiofemoral and patellofemoral joint surfaces, reduces peak stress on articular surfaces, and promotes more uniform stress distribution, thereby providing a therapeutic approach for early-stage knee osteoarthritis.