Updated: 5/31/2021

Idiopathic Chondromalacia Patellae

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  • 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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(OBQ12.99) A 15-year-old female cross country runner presents with 5 weeks of right knee pain. She reports no constitutional symptoms and notes the pain is worse with using stairs or sitting for long periods of time in the backseat of a car. Physical examination shows that her range of motion is full and there is no effusion. There is approximately one quadrant of passive medial or lateral patellar glide. She has pain with resisted open chain knee extension. There is more hip external rotation than internal rotation bilaterally and hip range of motion is painless. Radiographs of the right knee are found in Figures A-C. What is the next most appropriate step in management?

QID: 4459

Obtain AP, frog leg lateral, Dunn view, and false profile hip radiographs



CT scan to obtain tibial tubercle-trochlear groove measurements



Physical therapy regimen focused on quadriceps and core muscle strengthening program



Physical therapy regimen focused on Graston, ASTYM, and iontophoresis techniques



Obtain chest CT, skeletal survey, and refer to an orthopaedic oncologist



L 2 B

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