Theory 36/Tissue/Joint lubrication
Lubrication Needs a Film
The claim
Cartilage friction is set by the ratio of interstitial fluid film thickness to surface roughness, so wear begins when the film falls below the asperities.
01Mechanism
A continuous film separates surfaces; below the roughness scale, asperities touch and friction rises steeply.
02Prediction
Friction should jump at a film-to-roughness ratio.
03Refutation
Friction tracking load alone would remove the film.