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Ankle arthroscopy

Uses

  • Debridement of lateral soft tissue impingement
  • Anterior osteophytes
  • Loose bodies
  • Osteochondral fractures
  • Synovial biopsy & resection
  • Ankle fusion (when there is minimal deformity)

Superficial peroneal nerve anatomy

  • The superficial peroneal nerve divides into intermediate & medial dorsal cutaneous branches about 6.5cm proximal to the fibular tip
  • IDCN runs towards the 3-4 webspace
  • MDCN runs parallel & just lateral to the EHL tendon

Portals

  • Anteromedial – medial to tibialis anterior
    • Saphenous nerve
  • Anterolateral – lateral to peroneus tertius
    • 6mm medial to IDCN
    • intermediate branch of SPN
  • Posterolateral – lateral to Achilles tendon
    • 1.5cm proximal to fibula tip
    • Insert needle at 45° towards malleolus
  • (Posteromedial) – not used because of risk of damage to NV bundle
  • (Trans Achilles) – not used because of postoperative tendinitis

Technique

  • Position
    • general anesthesia
    • 30-degree 2.7-mm scope
    • Inflow through gravity assistance
    • Place the patient supine & apply a tourniquet around the midthigh
    • Use a thigh holder to hold the thigh in a slightly flexed position, with the end of the table flexed & the knee extended distally enough to prevent the table from impeding posterior instrumentation
    • inflate the tourniquet
  • bony landmarks
    • medial & lateral malleolar tips
  • incision
    • identify joint line is approximately 2.5 cm proximal to the lateral malleolus
    • insert 18-gauge spinal needle in the anteromedial portal site
      • direct it toward the center of the joint
      • inflate the joint with 20 ml of saline
      • watch for
        • bulging of the joint capsule laterally
        • return of fluid through the spinal needle
    • Make the lateral portal
      • Use a no. 11 blade to make a vertical 5-mm skin incision at the joint line
      • Use a haemostat
        • spread soft tissues down to the joint capsule
        • use a blunt trocar & cannula to enter the anterolateral capsule & pass toward the center of the joint
    • Make the anteromedial portal under direct vision
    • examine the ankle joint
    • Posterolateral portal may be necessary for evaluation of loose bodies
    • anteromedial compartment
      • deep portion of the deltoid ligament
      • medial talomalleolar articulation
      • medial tibiotalar joint
    • Moving centrally
      • examine the dome of the talus
      • corresponding tibial plafond
      • probe for articular damage
    • Traction with plantar flexion & dorsiflexion of the foot
      • improves exposure of the dome & articular surface
    • On the lateral side,
      • examine the lateral tibial plafond & corresponding talus
      • The talofibular articulation
      • lateral talomalleolar articulation
      • anterior talofibular ligament
    • Sweep the scope anteriorly & distally on the neck of the talus
      • to examine the anterior lip of the tibia & the neck of the talus for osteophyte formation
      • to examine the anterior gutter for loose bodies
    • Posterior compartment
      • In ankles with adequate ligamentous laxity, the posterior compartment also can be examined in a systematic fashion
      • including the posteromedial, central, & lateral tibiotalar articulations & the tibiofibular articulation
      • The posteroinferior tibiotalar ligaments & syndesmosis should be evaluated visually for chronic inflammation & manually stressed to evaluate stability
      • Loose bodies can become entrapped posterior to the tibiofibular ligaments
      • posterior ankle should be massaged to express potential loose bodies from this area
    • Examine the posterior gutter
      • for loose bodies & the posterior aspect of the talus for osteophyte formation that might impair range of motion
    • If a posterolateral portal
      • is needed for adequate evaluation, insert an 18-gauge needle just lateral to the tendo calcaneus & approximately 1 cm distal to the corresponding anterior portal to account for curvature of the talar dome
      • This portal is approximately 1.5 to 2 cm above the tip of the lateral malleolus
      • If an additional posterior portal is needed, the transtendinous portal, would seem to be safer & to have fewer complications than a posteromedial portal, but this has not been clinically proven
  • Postoperatively the wounds are closed with a stitch to avoid a synovial fistula

Complications

  • Overall rate of 9%.
    • Nerve damage
    • Saphenous nerve with anteromedial portal
    • Intermediate branch of SPN with lateral portal
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