Chondromalacia patellae

Chondromalacia patellae refers to softening and degeneration of the articular hyaline cartilage of the patella and is a frequent cause of anterior knee pain.

Tends to occur in young adults. There is a recognised female predilection.

Associations

Chondromalacia patellae can either occur in isolation or secondary to other conditions, including 1-4:

Patients with chondromalacia patellae usually present with anterior knee pain on walking up or down stairs. Additionally, there may be knee pain when kneeling or squatting or after sitting for long periods of time. Knee stiffness, crepitus and effusions may also be present.  In some cases, a history of patellar dislocation may be present 4.

Plain radiograph

Plain radiographs of the knee cannot assess for chondral changes and can only demonstrate features of osteoarthritis (OA) involving the patellofemoral joint in end-stage disease. A joint effusion may be visible.

CT

CT arthrograms can be used to diagnose plicae and focal cartilage defects but are insensitive to early chondral injury 3.

MRI

MRI is the modality of choice for assessing patellar cartilage.

  • T1
    • poor sequence for cartilage and surface irregularity and subtly signal change may be inapparent
    • areas of hypointensity may be seen in cartilage
    • subchondral reactive bone marrow oedema pattern (low signal)
    • secondary changes of osteoarthritis may be seen 
  • T2/PD
    • best sequences for assessing cartilage
    • abnormal cartilage is usually of high signal compared to normal cartilage
    • findings range from subtle increase in signal to complete loss of cartilage
    • the grading system of chondromalacia patella is based on T2/PD weighted MRI findings and arthroscopic correlation: see Chondromalacia grading  Outebridge method or modified Noyes

In the absence of an effusion, plicae may be difficult to identify 3.

Nonoperative treatment

Initial management is with a reduction of strenuous activities, NSAIDs and exercises to stretch and strengthen quadriceps muscle (especially vastus medialis) 4.

Operative treatment

A variety of operative options exists including 4:

  • arthroscopic debridement and lavage: diagnostic but only offers short term symptomatic relief
  • articular resurfacing
  • surgical correction for instability
  • patellectomy

General imaging differential considerations include:


Knee pathology

The knee is a complex synovial joint that can be affected by a range of pathologies:

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Article Information

rID: 9173
Section: Pathology
Tag: knee
Synonyms or Alternate Spellings:
  • Patellofemoral syndrome
  • Patellofemoral chondromalacia
  • Chondromalacia patella

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