Tendinopathy as Cyclic-Fatigue Unjamming of the Tendon Collagen Network
Tendinopathy is the tendon analogue of osteoarthritis: cyclic-fatigue unjamming of a load-bearing collagen network. Overuse drives the same Paris/Basquin damage law (§12) on the tendon contact number, so fibres are lost progressively — 25.6% at overuse — while sub-threshold use is protected and loss accelerates with overuse. Shape verified [V] on the cited damage-law form.
A tendon is a load-bearing collagen contact network; tendinopathy is its cyclic-fatigue degeneration under overuse. Reusing the OA Paris/Basquin law (exponent m=2, FORM cited) on the tendon contact number: sub-threshold use is protected, fibre loss rises with overuse load and is convex. Same kernel, different tissue. Shape [V]; damage-law form [L]; absolute progression rate [O].
The same unjamming, a different tissue
Tendon is modelled as a load-bearing collagen network — the same kind of contact-number order parameter as cartilage. Tendinopathy is overuse fatigue of that network: repetitive supra-threshold loading accumulates damage and progressively degrades the collagen, exactly as cyclic loading unjams cartilage in OA. So the OA fatigue kernel transfers directly, with no new mechanism, only a different tissue.
Sub-threshold protected, overuse accelerates
| loading | σ/σ* | final contact no. | fibre loss |
|---|---|---|---|
| rest (sub-threshold) | 0.8× | 1.000 | 0.000 |
| normal use | 1.3× | 0.964 | 0.036 |
| overuse | 1.8× | 0.744 | 0.256 |
| severe overuse | 2.3× | 0.324 | 0.676 |
Rest and sub-threshold use are protected (no loss); fibre loss rises with overuse load and is convex — the documented dose effect of training overload. The mechanism is collagen-network unjamming under cyclic fatigue.
What is NOT claimed
The SHAPE is the result and the Paris/Basquin damage-law FORM is cited [L]; the absolute progression rate (the rate constant) is not fixed by the substrate and stays [O]. Tendinopathy was a registered open-material item in the previous version; giving it the OA kernel moves it from [O] to a verified shape, while the absolute rate remains open.
Analgesic lever map (cross-reference)
Tendinopathy pain reuses the same cyclic-fatigue kernel, so the L2 (deload) lever lowers both the crossing rate and the tendon contact loss; the mirror disease-modifying step then ADDS eccentric loading, a separate up-step that is not analgesia. See §25 the three-lever threshold logic for the inherited technique (concept DOI 10.5281/zenodo.20733420), and §26 L2 convergence for the worked lever sweeps. The analgesic axis adds no new physics: pain is a threshold-crossing rate on the same R19 barrier this chapter already uses.