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Chondromalacia Patella

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Other Names

  • Chondromalacia Patellae (CMP)
  • Chondromalacia of the patella
  • Patellar chondral defects
  • Idiopathic Chondromalacia Patellae


  • This page refers to chondromalacia of the Patella (CMP), a degenerative process of the articular cartilage


  • First described by Budinger in 1906 (need citation)
  • Chondromalacia is derived from the Greek words
    • Chrondros: cartilage
    • Malakia: softening


  • Overall, epidemiology is poorly understood
  • Men > women (need citation)
  • Most common cause of chronic knee pain


  • General: Chondromalacia (Main)
    • The undersurface of the patella is covered with hyaline cartilage that articulates with the hyaline cartilage femoral groove
    • Chondromalacia is defined by softening and then subsequent tearing, fissuring, and erosion of hyaline cartilage
    • Causes include post-traumatic injuries, microtrauma wear and tear, and iatrogenic injections of medication
  • Pain generation
    • Poorly understood and likely multifactorial


  • Overuse
    • Majority of chondromalacia associated with repetitive microtrauma of the patellofemoral hyaline cartilage
  • Patella Tracking issues
  • Other etiologies that can cause quad atrophy
    • Complication of knee trauma
    • Immobilization
    • Surgical procedures


Risk Factors

  • Biomechanical
  • Muscle
    • Tight Rectus Femorus
    • Tight Tensa Fascia lata
    • Tight Hamstrings
    • Tight Gastrocnemius
    • Vastus medialis insufficiency

Differential Diagnosis

Clinical Features

  • History
    • Patients will complain of anterior knee pain
    • Worse with stairs, squatting, kneeling, running, prolonged periods of sitting
    • May complain of bucking due to quadriceps inhibition reflex
    • Onset is insidious
  • Physical Exam: Physical Exam Knee
    • Quadriceps muscle atrophy may be present
    • Tenderness on palpating under the medial or lateral border of the patella
    • Crepitus with range of motion
    • Swelling/ effusion is often mild to non-exist




  • Findings
    • Increased signal in cartilage


  • Indications
    • Fracture
    • Evaluate patellofemoral alignment
  • Findings
    • Trochlear Geometry
    • Tibial-tuberosity to trochlear groove distance (TT-TG distance)


  • Ultrasound is generally not indicated
  • May be used to evaluate other causes of anterior knee pain


Outerbridge Classification

  • Describes the severity of the degenerative process
    • As seen on arthroscopy or MRI (fat saturated sequences)
    • Often varied within the same knee
  • Level 1
    • Softening or swelling of the cartilage
    • Arthroscopy: focal areas of hyper intensity with normal contour
  • Level 2
    • Defined by fibrillation, fragmentation of the hyaline cartilage
    • Arthroscopy: blister-like swelling/fraying of articular cartilage extending to surface
  • Level 3
    • Fissuring of the articular cartilage to the level of subchondral bone, crab-meat appearance
    • Arthroscopy: partial thickness cartilage loss with focal ulceration
  • Level 4
    • Eburnated bone devoid of articular cartilage covering.
    • Arthroscopy: cartilage loss with underlying bone reactive changes



  • There is no definitive cure for chondromalacia patella


Regenerative Therapy


  • Indications
    • Refractory cases
  • Technique
    • Chondral debridement
    • Plica release
    • Lateral retinacular release
    • Patellar realignment surgery

Rehab and Return to Play


  • No established guidelines

Return to Play

  • No established guidelines


See Also


  1. Pak, Jaewoo, Jung Hun Lee, and Sang Hee Lee. "A novel biological approach to treat chondromalacia patellae." PloS one 8.5 (2013): e64569.
  2. Hauser, Ross A., and Ingrid Schaefer Sprague. "Outcomes of prolotherapy in chondromalacia patella patients: improvements in pain level and function." Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders 7 (2014): CMAMD-S13098.
Created by:
John Kiel on 23 February 2021 16:12:10
Last edited:
4 October 2022 15:54:18