Table 1.

Epidemiology, etiology, and pathology of canine and human anterior cruciate ligament (ACL) rupture

Parameter	Canine ACL rupture	Human ACL rupture
Heritability	0.27–0.48 in high-risk breeds	Unknown
ACL bundles	Anteromedial and posterolateral	Anteromedial and posterolateral
Sex	Increased risk with neutering	Increased risk in athletic females
Incidence	Up to ~ 2610/100,000 dogs per year in high-risk breeds	~ 13.5–75/100,000 persons per year
Pathophysiology	Mainly non-contact rupture	Mainly non-contact rupture
Prodromal fiber rupture	Typical	Unknown
Contralateral ACL rupture	Up to 73% of cases	Up to 12.5% of cases
Secondary meniscal damage	Typical	Typical
Development of knee OA	Associated with ACL fiber rupture, often precedes knee instability	Multifactorial, often follows ACL rupture
Epidemiological risk factors	Breed, neutering, obesity	Increased risk in women. Activity that increases shoe playing surface friction and torsional forces
Molecular pathways	Altered ECM homeostasis and synovitis	Altered ECM homeostasis

ACL anterior cruciate ligament, ECM extracellular matrix, OA osteoarthritis