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Updated: May 31 2021

Idiopathic Chondromalacia Patellae


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Images chondro grade ii.jpg
  • summary
    • Idiopathic chondromalacia patellae is a condition characterized by idiopathic articular changes of the patella leading to anterior knee pain.
    • Diagnosis is clinical with a history of anterior knee pain made worse with squatting, prolonged sitting or ascending stairs and pain on patellar compression in knee extension.
    • Treatment is generally nonoperative with resting, ice, activity modifications and physical therapy to focus on hamstring, quadriceps and core strengthening.
  • Epidemiology
    • Demographics
      • most common occurs in adolescents and young adults
      • women > men
  • Etiology
    • Pathophysiology
      • pain generator is not clearly understood and multi-factorial
        • may result from roughening or damage to the undersurface cartilage of the patella
        • numerous factors have been proposed including
          • limb malaligment
          • muscle weakness
          • chondral lesions
          • patella maltracking
            • patella maltracking can create narrow contact pressure points and further attenuate pain.
            • elevated contact pressures between patella and femoral groove are associated with anterior knee pain
    • Associated conditions
      • miserable malalignment syndrome
        • a term coined for anatomic characteristics that lead to an increased Q angle and an exacerbation of patellofemoral dysplasia. They include
          • femoral anteversion
          • genu valgum
          • external tibial torsion / pronated feet
  • Anatomy
    • Patellofemoral joint
      • articulation between patella and intracondylar groove of femur
    • Pain receptors of the knee
      • subchondral bone has weak potential to generate pain signals
      • anterior fat pad and joint capsule have highest potential for pain signals
  • Classification
      • Outerbridge MRI Classification of Chondromalacia
      • Grade 0
      • Normal Cartilage
      • Grade I
      • Surface intact and heterogenous; high signal intensity
      • Grade II
      • Fissures and fragmentation extending down to the articular surface
      • Grade III
      • Partial thickness defect, with focal ulceration
      • Grade IV
      • Exposed subchondral bone
  • Presentation
    • Symptoms
      • diffuse pain in the peripatellar or retropatellar area of the knee (major symptom)
      • insidious onset and typically vague in nature
      • aggravated by specific daily activities including
        • climbing or descending stairs
        • prolonged sitting with knee bent (known as theatre pain)
        • squatting or kneeling
      • always consider the physical, mental and social elements of knee pain
    • Physical exam
      • quadricep muscle atrophy
      • signs of patella maltracking
        • increased femoral anteversion or tibial external rotation
        • lateral subluxation of patella or loss of medial patellar mobility
        • positive patellar apprehension test
      • palpable crepitus
      • pain with compression of patella with knee range of motion or resisted knee extension
  • Imaging
    • Radiographs
      • recommended views
        • AP, lateral and notch radiographs of knee
      • findings
        • may see chondrosis on xray
        • shallow sulcus, patella alta/baja, or lateral patella tilt
    • CT scan
      • indications
        • patellofemoral alignment
        • fracture
      • findings
        • trochlear geometry
        • TT-TG distance
        • torsion of the limb
    • MRI
      • indications
        • best modality to assess articular cartilage
      • views
        • T2 best sequence to assess cartilage
        • abnormal cartilage is usually of high signal compared to normal cartilage
  • Differential
    • Quadriceps or patellar tendinitis
    • Saphenous neuroma
    • Post-operative neuromas
  • Treatment
    • Nonoperative
      • rest, rehab, and NSAIDS
        • indications
          • mainstay of treatment and should be done for a minimum of one year
        • technique
          • NSAIDS are more effective than steroids
          • activity modification
          • rehabilitation with emphasis on
            • vastus medialis obiquus strengthening
            • core strengthening
            • closed chain short arc quadriceps exercises
            • strengthening of hip external rotators
    • Operative
      • arthroscopic debridement
        • indications
          • Outerbridge grade 2-3 chondromalacia patellofemoral joint
        • techniques
          • mechanical debridement
          • radiofrequency debridment
      • lateral retinacular release
        • indications
          • tight lateral retinacular capsule, loose medial capsule and lateral patellar tilt
        • techniques
          • open arthrotomy
          • arthroscopy
      • patellar realignment surgery
        • indications
          • severe symptoms that have failed to improve with extensive physical therapy
        • techniques
          • Maquet (anterior tubercle elevation)
            • only elevate 1 cm or else risk of skin necrosis
          • Fulkerson (anterior-medialization)
            • indications (controversial)
              • increased Q angle
              • patellar instability
            • contraindications
              • superior medial arthrosis (scope before you perform the surgery)
              • skeletal immaturity
          • Elmslie-Trillat osteotomy
          • MPFL reconstruction
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