Posterior approach to the Knee

Aims

Primary a neurovascular approach

Position

prone
longitudinal bolsters to support chest & abdomen & allow expansion

Landmarks

2 heads of gastrocnemius
semimembranosus & semitendinosis
biceps tendons

Incision

longitudinal gently curved incision
Start: laterally over the biceps femoris muscle
Obliquely across the popliteal fossa
End: over medial head of gastrocnemius & inferior over calf

Superficial Dissection

reflect the skin flaps
identify small saphenous vein & medial sural cutaneous nerve on it's lateral side (branch of tibial nerve)
incise the fascia of popliteal fossa medial to small saphenous vein
trace the media sural cutaneous nerve proximally back to it's source
dissect up to the apex of the popliteal fossa following the tibial nerve
dissect the common peroneal nerve at the apex of the popliteal fossa
- it runs along the posterior border of biceps femoris
identify the popliteal artery & vein
- lies deep & medial to tibial nerve
- artery has 5 branches
  - two superior
  - two inferior
  - one middle genicular artery
  - may need to be ligated to mobilise the artery
- Distally
  - Vein is medial to artery
  - Then it moves posterior to artery
  - Then lies posterolateral to artery above the knee joint

Deep Dissection

Retract the muscles that form the boundaries of popliteal fosa to expose the various parts of posterior joint capsule
Can detach either medial or lateral heads of gastrocnemius

Dangers

Nerves
- Medial sural cutaneous nerve
- Tibial nerve
- Common peroneal nerve
Vessels
- Small saphenous vein