The influence of infrapatellar fat pad resection on knee joint friction and damping: An in vitro study in New Zealand white rabbits

Abstract

The infrapatellar fat pad (IFP), an adipose tissue located in the anterior knee joint, is hypothesized to absorb shocks and aid in joint lubrication. We investigated the consequences of IFP removal on joint friction and damping in an in vitro animal model. The hindlimbs of female New Zealand white rabbits were dissected to retain the knee ligaments, joint capsule, and patellar retinaculum. Knees were mounted in a pendulum with the knee joint serving as the fulcrum while keeping the quadriceps tendon unloaded to assess joint friction and damping in each knee for three conditions: Control, Sham, and no IFP (IFP-R). Friction and damping were assessed under a 15N tibio-femoral joint load (40 % of body weight) at three flexion angles (50°, 100°, and 130°), and gyroscopic data were recorded to obtain the time decay of amplitude. Two models, a linear friction and an exponential decay friction model, were fit to the amplitude decay over time. The linear model provided Stanton's joint boundary friction coefficient (?L); the exponential decay model provided an exponential decay friction (?E) and a viscous damping (c) coefficient. When compared across all angles of testing, IFP removal decreased ?L by 6 % (p = 0.0057) vs Controls (?L = 0.0217 vs 0.0230); IFP removal decreased c by 9 % (p < 0.001) vs Controls (c = 0.00262 vs 0.00239 kgm2/s) and by 6 % vs Sham (p = 0.017, c = 0.00255 vs 0.00239 kgm2/s). IFP removal did not affect ?E (p = 0.12).

Publication Title

Journal of the Mechanical Behavior of Biomedical Materials

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