Updated: 2/14/2018

Knee Parapatellar Approach

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Introduction
  • Provides exposure to 
    • most structures of the anterior aspect of knee
      • is extensile
  • Indications
    • total knee arthroplasty
    • synovectomy
    • open medial menisectomy
    • open removal of loose bodies 
    • open ligamentous reconstructions 
    • patellectomy
    • I&D of knee
    • ORIF of distal femoral fractures
      • with a medial plate
  • Contraindications
    • relative
      • previous utilization of a lateral parapatellar arthrotomy
Preparation
  • Anesthesia
    • general
    • spinal, epidural, and/or femoral blocks
  • Position
    • supine
      • with sandbag below buttock to internally rotate operative leg
      • with sandbag on end of table to support heel when knee is flexed to 90 degrees
  • Tourniquet
Intermuscular Plane
  • Intermuscular plane
    • incise between
      • rectus femoris (femoral nerve) and
      • vastus medialis (femoral nerve) 
Preparation & Position
  • Anesthesia
    • spinal, epidural, sciatic and/or femoral blocks
  • Position
    • supine
    • tape sandbag under hip to externally rotate leg
  • Tourniquet
    • usually placed
Approach
  • Incision
    • landmark
      • palpate midline of patella in line to tibial tubercle
    • make midline longitudinal incision
      • beginning  5 cm above superior pole of the patella
      • extending to the level of the tibial tubercle
      • curved or straight incision can be used
        • and can be done with knee flexed
  • Superficial Dissection
    • divide subcutaneous tissues below skin incision
    • deepen dissection between the vastus medialis and quadriceps tendon
    • develop medial skin flap to expose the  quadriceps tendon, medial border of the patella, and medial border of the patellar tendon
    • perform medial parapatellar arthrotomy 
      • taking care not to damage the anterior insertion of the medial meniscus (irrelevant for TKA)
    • retract or excise the infrapatellar fat pad
  • Deep dissection
    • dislocate patella and flip laterally
      • try to protect insertion of patellar tendon on tibia
      • if difficult to flip patella then extend incision between rectus femoris and vastus medialis proximally
      • if contractures continue to prevent dislocation of the patella then can detach tibial tuberosity bone block and reattach afterwards with a screw
    • flex knee to 90 degrees to gain exposure to entire knee joint
  • Extension
    • proximal
      • may extend to distal two thirds of femur
      • incise between rectus femoris and vastus medialis
      • split underlying vastus intermedius to expose femur
  • Variations
    • midvastus approach
      • proximal portion of the arthrotomy extends into the muscle belly of the vastus medialis 
      • patella can be difficult to evert and is subluxated laterally instead
    • subvastus (Southern) parapatellar approach 
      • muscle belly of the vastus medialis is lifted off the intermuscular septum
      • patella can be difficult to evert and is subluxated laterally instead
      • benefits include
        • preserving the blood supply to the patella
        • preserving the anatomy of the quadriceps tendon (maintains stability of knee)
Dangers
  • Superior lateral genicular artery
    • at risk during lateral retinacular release
    • may be last remaining blood supply after medial parapatellar approach and fat pad excision
  • Infrapatellar branch of saphenous nerves
    • saphenous nerve becomes subcutaneous on medial aspect of knee after piercing the fascia lata between the sartorius and gracilis
    • saphenous nerve then gives of infrapatellar branch that provides sensory to the anteromedial aspect of the knee
    • injury can lead to postoperative neuroma
      • if cut during surgery, resect and bury end to decrease chance of painful neuroma
 

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