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Osteonecrosis of the Knee
Updated: Oct 4 2016

Microfracture of the Knee

Preoperative Patient Care
Operative Techniques

Preoperative Plan


Determine pathology using MRI

  • radial tear
  • horizontal cleavage tear
  • displaced bucket handle tear
  • meniscal root tear
  • discoid meniscus


Execute surgical walkthrough

  • describe steps of the procedure verbally to the attending prior to the start of the case
  • describe potential complications and steps to avoid them

Room Preparation


Surgical Instrumentation

  • standard arthroscopy pump
  • motorized meniscal shaver
  • toothed grasper
  • double loaded 2-0 or 0 nonabsorbable sutures with long flexible needles


Room setup and Equipment

  • standard OR table with leg holder


Patient Positioning

  • supine
  • leg holders
  • place leg holder 5 to 8 cm proximal to the superior pole of the patella to maximize control of the limb
  • contralateral leg is placed in a well leg holder
  • for the diagnostic portion of the procedure is placed at the foot of the bed
  • for the remainder of the procedure, the foot of the bed is dropped

Scope Insertion


Mark out the anatomy of the knee

  • draw out the patella, patellar tendon, medial and lateral joint lines and the posterior contours of the medial and lateral femoral condyles


Place anterolateral portal

  • use 22 gauge needle on syringe and bury the needle
  • make wheal at skin and then 11 blade in same direction as the needle
  • place scope in same direction as needle and blade
  • hug the patellar tendon


Place anteromedial portal

  • place knee in 30 degrees of flexion with valgus moment applied
  • use a spinal needle to assess direction and appropriate superior/inferior direction.
  • visualize with lateral portal

Diagnostic Arthroscopy



  • suprapatellar pouch
  • patellofemoral joint (take picture)
  • place bump under heel prn
  • lateral gutter
  • look for loose bodies and peripheral tears of LM
  • get MFC in view
  • bring knee into slight flexion and valgus as you go into medial compartment.
  • foot goes on to opposite hip and use standee to stabilize your foot
  • medial meniscus (take picture)
  • drop leg to flexion (bump should be under knee)


Establish far anteromedial portal

  • use 18-gauge needle to make sure that you clear the MFC and can get to the 2 o’clock (LEFT) or 10 o’clock (RIGHT) knee



  • medial compartment - probe medial meniscus, articular cartilage
  • intercondylar notch – ACL/PCL (take picture)
  • lateral compartment – probe lateral meniscus, articular cartilage (take picture)
  • assess the full thickness articular lesion

Initial Preparation


Debride all unstable cartilage

  • debride all of the exposed bone of all remaining unstable cartilage
  • use a hand held curved curette and a full thickness radius resector to debride the cartilage
  • it is critical to debride all loose or marginally attached tissue from the surrounding rim of the lesion


Remove the calcified cartilage layer

  • remove the calcified cartilage layer that remains as a cap to many lesions
  • this is preferabely done with a curette
  • thorough and complete removal of the calcified cartilage layer is extremely important


Maintain the integrity of the subchondral plate

  • do not debride to deeply
  • the prepared lesion with a stable perpendicular edge of healthy well attached viable cartilage surrounding the defect provides a pool that helps hold the marrow clot (super clot) as it forms



Make multiple holes

  • these are microfractures in the exposed subchondral bone plate
  • use an awl with an angle that permits the tip to be perpendicular to the bone as it is advanced
  • typically this is 30 or 45 degrees
  • use a 90 degree awl on the patella or other soft bone
  • this should only be advanced manually


Position the holes appropriately

  • make the holes close together but not so close that one breaks into another IE breaking the subchondral plate between them
  • this usually results in microfracture holes that are approximately 3 to 4 mm apart


Determine the appropriate depth of the holes

  • when fat droplets can be seen coming from the marrow cavity, the appropriate depth of 2-4 mm has been reached


Drill holes in the appropriate order

  • microfracture holes around the periphery of the defect should be made first
  • these holes should be made immediately adjacent to the healthy stable cartilage rim
  • complete the process by making the microfracture holes towards the center of the defect

Wound Closure


Use 3-0 and 4-0 biosyn for closure

  • Apply steristrips


Cover with tegaderm and occlusive dressings

Postoperative Patient Care
Private Note

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