Table 1 Epidemiology, etiology, and pathology of canine and human anterior cruciate ligament (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