Knee – Posterior Approach

Modern Study Review (AI-Generated)

High-Yield Summary

The posterior approach to the knee offers direct access to the popliteal fossa and posterior joint capsule, essential for managing complex posterior knee pathologies such as neurovascular injuries, posterior capsule repair, and tumor excision. It is a technically demanding approach without a true internervous plane, requiring meticulous dissection to protect critical neurovascular structures. While still indispensable in select cases, this approach has been partially supplanted by arthroscopic and less invasive techniques for many posterior knee conditions.

Applied Anatomy & Intervals

Internervous Interval

• None: This approach lacks a defined internervous plane and necessitates careful dissection around multiple nerves.

Anatomic Landmarks

• Biceps femoris (BF) tendon laterally
• Medial and lateral heads of gastrocnemius muscle
• Popliteal fossa crease
• Lesser saphenous vein (central in fossa)
• Tibial nerve and common peroneal nerve (CPN) at apex of popliteal fossa

Patient Positioning & Setup

• Table Type: Standard operating table with tourniquet capability
• Patient Position: Supine with knee flexed (supported by bump or sandbag to relax posterior structures)
• Specialized Equipment:
• Pneumatic thigh tourniquet for bloodless field
• Limb positioner or assistant to maintain knee flexion
• C-arm fluoroscopy positioned laterally if intraoperative imaging is needed

Surgical Technique (The “Vital Steps”)

Incision & Superficial Dissection

• Make a longitudinal or slightly oblique incision starting lateral over the biceps femoris, curving obliquely across the popliteal fossa, then turning down over the medial head of the gastrocnemius.
• Reflect skin flaps carefully to preserve subcutaneous neurovascular structures.

Deep Dissection & Exposure

• Identify and preserve the lesser saphenous vein running centrally in the fossa.
• Locate the medial sural cutaneous nerve lateral to the lesser saphenous vein; incise fascia just medial to the vein to avoid nerve injury.
• Trace the medial sural nerve proximally to the tibial nerve.
• Follow the tibial nerve proximally to the apex of the popliteal fossa where the common peroneal nerve branches off laterally.
• Identify popliteal artery and vein; artery lies lateral to vein as it enters the fossa, then moves posteriorly and laterally above the knee joint.
• For posteromedial capsule exposure, detach the origin of the medial head of gastrocnemius from the femur and retract it laterally and inferiorly.
• For posterolateral corner exposure, detach the lateral head of gastrocnemius from the lateral femoral condyle and develop the interval between the lateral gastrocnemius and biceps femoris.
• Incise the posterior joint capsule as needed for access.

The “Danger Zone”

Post-Operative Pearl

Limit knee extension initially to protect the repaired posterior capsule and neurovascular structures. Early controlled range of motion is encouraged to prevent stiffness, but avoid hyperextension for 4-6 weeks.

Classic Clinical Notes

Knee – Posterior Approach

• Position: Supine & tourniquet

• Incision:
• Start lateral over biceps femoris (BF) and bring incision obliquely across popliteal fossa
• Turn down over medial head of gastrocnemius

• No internervous plane

• Dissection:
• Reflect skin flaps
• Expose lesser saphenous vein
• Running lateral to vein is medial sural nerve (branch of tibial nerve)
• Incise fascia of popliteal fossa just medial to lesser saphenous vein
• Trace medial sural nerve back to tibial nerve
• Dissect up to apex of popliteal fossa following tibial nerve
• At apex, common peroneal nerve (CPN) separates from tibial nerve
• Identify popliteal artery & vein
• Artery has 5 branches — 2 superior, 2 inferior & 1 middle genicular artery
• Vein lies medial to artery as it enters popliteal fossa from below
• Curves lying directly posterior while in fossa
• Moves to posterolateral side of artery above knee joint

• Posteromedial joint capsule:
• Detach origin of medial head of gastrocnemius from back of femur
• Retract head lateral & inferior
• Expose posteromedial joint

• Posterolateral corner:
• Detach origin of lateral head of gastrocnemius from lateral femoral condyle
• Develop interval between gastrocnemius & BF
• Incise joint capsule

• Dangers:
• Medial sural nerve — lies lateral to lesser saphenous vein so incise fascia medial to vein
• Tibial nerve
• Common peroneal nerve (CPN)
• Popliteal vessels

Last Updated on January 25, 2026 by orthonet