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Condition/Disorder Synonyms

  • Patella tendonitis

  • Jumper's knee

  • Infrapatellar tendinitis

ICD-9-CM Code

  • 726.64 Patellar tendinitis

ICD-10-CM Code

  • M76.50 Patellar tendinitis, unspecified knee

Preferred Practice Pattern1

Key Features


  • 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

Clinical Findings

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

Means of Confirmation or Diagnosis


  • Ultrasonography

  • MRI

  • X-ray

Findings and Interpretations

  • Hypertrophic tendon

  • Hyperechoic mass at midtendon

  • Irregular tendon structure



  • NSAIDs

  • Prolotherapy: sclerotic injection (most common dextrose)

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