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quadriceps-tendon-rupture-pathogenesis-and-clinical-findings

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