In this paper, stress distribution in patella was studies by 3-D photoelastic experiments and finite element calculations. The experimental conditions were in good agreement with that of body mechanics: (1) The ratios of m. quadriceps femoris force F_Q to lig. patella force F_P were 1.03-1.42. (2) The angles between F_Q and F_P were 8.4°-18.7°. (3) The ratio of modulus of elasticity for epoxy resin and silicone rubber matched that for patella and cartilage, i.e., 145:1.

The principal stresses and their path line, normal stresses, contact stresses between patella and ossis femoris were determined in various flexion angles (15°, 30°, 45°, 60°, 75°, 90°). Two of the correlations were:

(1) Maximum principal stress in the front of patella

σ_max=35.8Wexp(0.024α) KPa

(2) Maximum contact stress between patella and ossis femoris

σ_max=−(6.86−0.14α+0.02α²)W KPa

where W was body weight subjected by a single foot.

It was proved that the transverse break of patella resulted from the case that the principal stress in the front of patella exceeded ultimate tensile strength. And Tension Band Wiring (TBW) therapy conformed to the law of physiological stress field. A modified K-needles position in TBW therapy was suggested. These results are useful for further research of human patella mechanics and recovery therapy. No similar result has been found in American MEDLIN Data Bank.

Date Published: 1 December 1991
PDF
Proc. SPIE 1554, Second International Conference on Photomechanics and Speckle Metrology, (1 December 1991); doi: 10.1117/12.49563

Published in SPIE Proceedings Vol. 1554:
Second International Conference on Photomechanics and Speckle Metrology
Fu-Pen Chiang; Fu-Pen Chiang, Editor(s)