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patellar-tendon-rupture-pathogenesis-and-clinical-findings

Patellar Tendon Rupture: Pathogenesis and clinical findings Author: Molly Joffe Reviewers: Liam Thompson, Alyssa Federico, Tara Shannon, Gentson Leung* *MD at time of publication Chronic disease (e.g. renal failure, gout, rheumatoid arthritis, and diabetes) Repetitive activities involving rapid knee flexion and extension Tendon inflammation and micro-tearing Fluoroquinolone (antibiotic class) use Smoking Immobilization of knee ↓ Muscle and tendon flexibility and strength Steroid use (including intraarticular injections) Changes in collagen fibrils composing tendon (exact mechanism unknown) Disrupted blood supply to tendon and poor healing Compromised integrity and strength of the tendon Sudden heavy load on flexed knee while foot is planted Quadriceps muscles contract while lengthening (eccentric contraction)àforce exceeds tendon strength Patellar tendon innervated by common peroneal (fibular) nerve Nociceptors (pain receptors) within tendon activated by tendon rupture Pain and tenderness below the patella Collagen fibres in tendon tear Tearing or popping sensation at time of injury Patellar Tendon Rupture Tendon/Ligament detaches from bony attachment on patella or tibial tubercle No connection of quadriceps to tibia via patellar tendon ↑ Force on tibial tubercle during tendon detachment Avulsion fracture of tibial tubercle Trauma to tendon ruptures surrounding blood vessels Coagulation cascade and inflammatory mediators released at rupture site Quadriceps muscles unable to stabilize patellar tracking Instability of knee joint Quadriceps muscle tension pulls patella upwards with no resistance from patellar tendon Patellar tendon cannot use distal attachment site for leverage Knee extensor muscles unable to effectively contract Knee buckling Abnormal gait Patella alta (high sitting patella) on X-ray Palpable gap below the patella Bruising below the patella Swelling below the patella ↑ Risk of falls Loss of patellar reflex Inability to perform a straight leg raise (hip flexes and knee cannot remain straight) Hematoma (blood collection under the skin) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 28, 2022 on www.thecalgaryguide.com