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  • Patella tendonitis
  • Jumper’s knee
  • Infrapatellar tendinitis

  • 726.64 Patellar tendinitis

  • M76.50 Patellar tendinitis, unspecified knee


  • Fibers in the middle portion of the tendon breakdown, degenerate, swell, and thicken.
  • Pain common in inferior patella region
  • Overload of eccentric quadriceps contraction
  • Typically lacks the presence of inflammatory cells
    • Terms “tendonitis” or “tendinitis” incorrect
  • Typically associated with tissue degeneration
    • Two Types
      • Lipoid: fatty tissue deposited in the tendon
      • Mucoid: conversion of tendon in softer material with gray or brown appearance
    • Thickening of tendon
    • Neovascularization
    • Increased presence of varicose nerve fibers
      • Most likely source of pain

Essentials of Diagnosis

  • Insidious onset
  • Improves initially with movement
  • Diagnosis made by patient history and clinical examination
  • Ultrasound or MRI

General Considerations

  • Must address training errors and biomechanics deficits to prevent recurrence
  • Is it truly a tendon? It runs from the patella (bone) to the tibia (bone), which would be labeled as a ligament.


  • People participating in athletic activity (though, it also occurs in sedentary individuals)
    • Runners
    • Jumping sports
  • Onset more common during training verse competitive event

Signs and Symptoms

  • Pain with palpation of tendon
  • Pain in anterior knee
  • Tenderness changes position with tendon movement during extension
  • Increased swelling throughout the day
  • Thickening of the tendon
  • Decreased flexion ROM
  • Decreased extension strength

Functional Implications

  • Inability to climb stairs or ladder
  • Inability to push-off during ambulation
  • Decreased stride length during ambulation
  • Decreased squat depth

Possible Contributing Causes

  • Intrinsic risk factors
    • Decreased knee flexion ROM
    • Decreased quadriceps strength
    • Greater pronation/calcaneal varus and faster rate of maximum pronation
    • Obesity
    • Patella alta
    • Muscle imbalance
    • Hyperlipidemia
    • Hypertension
    • Increased Q angle
  • Extrinsic risk factors
    • Training errors
      • Sudden increase in mileage or intensity or incline
      • Increasing in jumping
      • Return too fast from inactivity
    • Environmental factors
      • High incidence with training in cold weather
    • Faulty equipment
      • Surface too hard
      • Shoes not supportive

Differential Diagnosis

  • Tendon rupture
  • Tendon partial tear
  • Bone spur
  • Chondromalacia
  • Bursitis
  • Meniscal tear
  • ACL instability
  • L4 radiculopathy
  • Osgood-Schlatter
  • Sinding-Larsen Johansson disease
  • Osteoarthritis


  • Ultrasonography
  • MRI
  • X-ray

  • Hypertrophic tendon
  • Hyperechoic mass at midtendon
  • Irregular tendon structure


  • NSAIDs
  • Prolotherapy: sclerotic injection (most common dextrose)

Medical Procedures

  • Tendon debridement
  • Extracorpeal shock wave therapy (ESWT)

  • For imaging, radiologist
  • For injection, orthopeadist

  • Pain with movement after prolonged immobility with the knee flexed (i.e. after sitting at a desk, driving, movies) ...

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