Updated: 2/26/2017

Posterior Approach to Knee

Review Topic
  • Introduction
    • Overview
      • primarily a neurovascular approach
      • pathology related to posterolateral and posteromedial corners of the knee should be approached using lateral and medial approaches to knee respectively
    • Indications
      • neurovascular repair in traumatic injury
      • PCL avulsion repair
      • gastrocnemius recession in knee contractures
      • hamstring lengthening
      • Baker's / popliteal cyst excision
      • tibial nerve compression by soleus
  • Key Anatomy
    • Muscles
      • gastrocnemius
      • semimembranosus
      • semitendinosus
    • Nerves
      • medial sural nerve
    • Vessels
      • small saphenous vein
      • popliteal artery and vein
      • genicular vessels (two superior, two inferior, one middle)
  • Internervous Plane
    • The is no true internervous plane
  • Preparation & Positioning
    • Preparation
      • table
        • use radioopaque table when performing fixation (PCL avulsion)
      • tourniquet
        • used in most cases except when a vascular repair is being performed
        • may delay exsanguination until vein is identified
    • Position
      • patient is placed prone
  • Approach
    • Incision
      • identify superficial landmarks
        • gastrocnemius
        • semimembranous
        • semitendinosus
        • biceps femoris
      • make lazy-S incision running
        • from lateral biceps femoris
        • to medial head of gastrocnemius muscle and into calf
    • Superficial Dissection
      • make subcutaneous skin flaps
        • generous skin flaps will facilitate closure
      • identify small saphenous vein and medial sural nerve
        • medial sural nerve runs on lateral side of vein
        • small sapheneous vein can assist in locating the medial sural nerve
        • the medial sural nerve is a branch of the tibial nerve and can be used as a guide and into popliteal fossa
      • incise fascia of popliteal fossa
        • make fascial incision just medial to small saphenous vein
      • disect to apex of popliteal fossa
        • use tibia nerve as a guide to apex of popliteal fossa
        • apex is formed by semimembranous (medial) and biceps femoris (lateral)
      • mobilize common peroneal nerve
        • branches from tibial nerve at apex of popliteal fossa
        • runs along posterior border of biceps femoris
      • mobilize popliteal artery and vein
        • lies deep and medial to tibial nerve
        • popliteal vein lies medial to artery as it enters the fossa, then it curves and lies directly posterior to the artery at the midpoint in the fossa
        • must identify and ligate at least one of the five genicular branches in the posterior knee that include
    • Deep Dissection
      • evaluate posteromedial joint capsule
        • faciliated by detaching medial head of gatrocnemius at origin
      • evaluate posterolateral corner of joint
        • develop plane between lateral head of gastrocnemius and biceps femoris
        • faciliated by detaching lateral head of gatrocnemius at origin
  • Dangers & Complications
    • Medial sural cutaneous nerve injury
      • avoid injury by entering fossa medial medial to small saphenous vein (nerve lies lateral)
      • injury make lead to painful neuroma or anesthesia
    • Tibial nerve injury
      • injury at this level leads to paralysis of foot and toes flexors
    • Common peroneal nerve injury
      • injury at this level leads to paralysis of extensors and evertor of the foot
    • Popliteal artery

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