Posterior Approach To Knee Joint

The posterior approach to knee joint is neurovascular approach primarily.
It’s rarely is needed by orthopedic surgeon because the medial and lateral approaches each provide good access to half the posterior capsule.
The posterior approach to knee joint uses include:
1. Repair of the neurovascular structures in the popliteal fossa.
2. Repair of avulsion fractures of the posterior cruciate ligament (it’s insertion to the tibia).
3. Recession of gastrocnemius muscle heads in cases of contracture.
4. Lengthening of hamstring tendons.
5. Excision of Baker’s cyst and other popliteal cysts.
6. Access to the posterior capsule of the knee .

Landmarks:
1. Gastrocnemius muscle.
2. Semimembranosus and semitendinosus
  muscles.
Incision:
1. Inverted L-shaped incision is made:
  - Horizontal limb is in Langer’s lines in the popliteal space.
  - Vertical limb begins at the medial corner of the popliteal fossa and extends distally.
2. S-curve incision:
  - Incision can be extended proximally on the lateral side for more extensile exposure.

There is No true internervous or intermuscular plane for the posterior approach to knee joint.
Dissection is maintained underneath the gastrocnemius muscle belly.

Tendon of the gastrocnemius is seen and the muscle is retracted laterally:
- the posterior aspect of the knee capsule is then seen.
Popliteus and soleus are subperiosteally elevated off the posterior tibia:
- this exposes almost all of the posterior tibia.

If additional medial access is necessary, the medial head of the gastrocnemius can be released.
Posterolateral extension should be limited due to risk of common peroneal nerve injury.

The structures at risk during the posterior approach to knee joint includes:
1. Popliteal artery:
  - Risk is minimized with maintenance of access under the gastrocnemius muscle.
2. Tibial nerve:
  - Risk is minimized with maintenance of access under the gastrocnemius muscle.
3. Sural nerve and short saphenous vein.