Table 1. Summary of key SASP components and inflammatory mediators implicated in post-traumatic osteoarthritis (PTOA).

SASP class	Representative mediators	Principal effects in PTOA	Key references
Pro-inflammatory cytokines	IL-6, IL-1β, TNF-α	Activate NF-κB / MAPK signalling; amplify catabolic gene expression	Loeser, Collins & Diekman (2016) and Goncalves et al. (2021)
Chemokines	CCL2, CCL5, CXCL8	Recruit monocytes/macrophages; sustain low-grade joint inflammation	Chambers et al. (2021)
Matrix-degrading proteases	MMP-13, ADAMTS-5	Cleave type II collagen & aggrecan; MMP activity remains elevated even in macroscopically intact cartilage	Nie et al. (2019a) and Nie et al. (2019b)
Growth factors	ANGPTL2, GDF-15	Promote angiogenesis and bone remodelling; correlate with bone-density loss	Konstantinidi, Talage & Kennedy (2017)
Extracellular vesicles / microRNAs	miR-34a-enriched EVs	Mediate paracrine senescence; expand senescent cell pool	Basisty et al. (2020)