Quadriceps Tendon Rupture: Pathogenesis and clinical findings
Author:
Molly Joffe
Reviewers:
Liam Thompson, Alyssa Federico, Tara Shannon, Gentson Leung* *MD at time of publication
Repetitive activities involving, rapid, active flexion and extension of the knee
Quadriceps tendon inflammation and micro-tearing
Immobilization of leg/knee
Steroid use (including intraarticular injections)
Quadricep muscles atrophy
↓ Quadricep muscle strength
Smoking
Chronic disease (e.g. renal failure, gout, rheumatoid arthritis, and diabetes)
Fluoroquinolone (antibiotic class) use
Changes in collagen fibrils composing tendonàimpaired tendon strength (exact mechanism unknown)
Quadriceps tendon shortens
↓ Quadricep tendon flexibility
Disrupted blood supply to quadriceps tendon and poor healing
Compromised integrity of the quadriceps tendon and ↓ strength
Sudden heavy load on flexed knee while foot is plantedàquadriceps muscles contract while lengthening (eccentric contraction)
Force on quadriceps tendon exceeds its strength
Quadriceps Tendon Rupture
Tendon detaches from bony attachment on patella
↑ Force on patella during quadriceps tendon detachment
Collagen fibres in quadriceps tendon tear
No connection of quadriceps to tibia via quadriceps tendon
Patellar tendon tension pulls patella downwards with no resistance from quadriceps muscles
Quadriceps tendon innervated by common peroneal (fibular) nerve
Nociceptors (pain receptors) within tendon activated by tendon rupture
Pain and tenderness above the patella
Trauma to tendon ruptures blood vessels
Coagulation cascade and inflammatory mediators released at rupture site
Quadriceps muscles unable to stabilize patellar tracking
Knee joint instability
Patella baja (low sitting patella) on X-ray
Palpable gap above the patella
Loss of patellar reflex
Patellar tendon cannot use proximal attachment site for leverage
Knee extensor muscles unable to effectively contract
Inability to perform a straight leg raise (hip flexes while knee cannot remain straight)
Bruising above the patella
Swelling above the patella
Avulsion fracture of patella
Tearing or popping
sensation at time of injury
Knee buckling
Abnormal gait
↑ Risk of falls
Hematoma (blood collection under the skin)
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published October 2, 2022 on www.thecalgaryguide.com