Finite Element Analysis of Patellofemoral Contact Pressure with Varying Fixation of Transverse Patella Fractures.

Abstract

Background: Understanding patellofemoral contact pressure is crucial for knee biomechanics, as abnormalities can lead to joint issues. This study investigates the changes in contact pressure after surgical fixation of patellar fractures.

Methods: Finite element model of the knee was created using cadaveric data on transverse patellar fractures. Models were analyzed and evaluated at 0°, 45°, and 90° flexion under quadriceps force to assess peak pressure, contact pattern, and pressure irregularity.

Results: The plate and wire fixation models exhibited distinct stress distribution patterns at 45° and 90° flexion angles. At 45°, the plate model had a higher peak stress (6.14 MPa) in a 21.0-mm ovular contact area, while the wire model had lower peak stress (2.42 MPa) in a smaller, more fragmented region. At 90°, the plate model exhibited concentrated stress (13.26 MPa) in a heart-shaped area, whereas the wire model had 3 dispersed stress points (9.88 MPa) over a broader surface. These findings highlight the plate model's greater stress concentration and the wire model's more irregular distribution of stress. At 0°, the plate model exhibited minimal contact pressure compared with the wire model, with a pressure of 6.67 MPa.

Conclusion: The plate model better preserves patellofemoral biomechanics, potentially reducing complications and improving long-term outcomes. Further research is needed to confirm its superiority as a fixation method.

Clinical relevance: Although the prevalence of patellar fractures remains high, the gold-standard method for surgical fixation has a postoperative complication rate as high as 52.5%. Addressing the lack of understanding surrounding patellofemoral contact pressure in this scenario is an essential step toward improving outcomes for these patients.