Medial Approach to Knee Joint

Medial Approach to Knee Joint indications:

The medial approach to knee joint provides a good exposure of the ligamentous structures on the medial side of the knee.

Medial Approach to Knee Joint indications include:

1. Repair of medial knee ligaments.
2. Medial meniscus tear repair or meniscectomy.
3. Anterior cruciate ligament injury repair.

See Also: Knee Meniscus Tear

Position of the Patient

• Place the patient supine on the operating table.
• Flex the affected knee to about 60, abduct and externally rotate the hip on that side, placing the foot on the opposite shin.

Landmarks and Incision

• Landmark:
  • Adductor tubercle along medial aspect of knee.
• Incision:
  • Make a long, curved incision, beginning at a point 2 cm proximal to the adductor tubercle of the femur. Curve it antero-inferiorly to a point 6 cm below the joint line on the anteromedial aspect of the tibia. The middle of this incision runs parallel to the medial border of the patella about 3 cm medial to it.

Internervous plane

• There is no true internervous plane in the medial approach to knee joint, because the nerves at the level of the knee pass posterior to the approach in the popliteal fossa, dissection is quite safe.
• The only cutaneous nerve that may be damaged is the saphenous nerve and its branches.

Superficial dissection

• Raise the skin flaps to expose the fascia.
• The exposure should extend from the midline anteriorly to the posteromedial corner of the knee posteriorly.

The infrapatellar branch of the saphenous nerve crosses the operative field transversely and is sacrificed; however, the saphenous nerve itself, which emerges from between the gracilis and sartorius muscles, must be preserved, as must the long saphenous vein in the posteromedial aspect of the dissection.
(The infrapatellar branch of the saphenous nerve should be cut and the end buried in fat to diminish the chances of the formation of a painful neuroma.)

Deep dissection

Exposing the deep structures within the knee involves incising the layers that cover them, either in front of or behind the superficial medial ligament (the medial collateral ligament).

These separate incisions provide access to the anterior and posterior parts of the medial side of the joint, respectively.

1. Anterior to the Superficial Medial Ligament:

Use the anterior approach to expose the superficial medial ligament, the anterior part of the medial meniscus, and the cruciate ligament.

• Incise the fascia along the anterior border of the sartorius muscle in line with the muscle’s fibers, starting from its attachment to the subcutaneous surface of the tibia and extending proximally to a point 5 cm above the joint line.
• The anterior border of the sartorius is hard to define at the level of the knee joint, so it should be sought either at the muscle’s tibial insertion or at the proximal end of the wound.
• Now, flex the knee further to allow the sartorius muscle to retract posteriorly, uncovering the other two components of the pes anserinus, the semitendinosus and gracilis muscles, which lie beneath and behind the sartorius.
• Retract all three muscles posteriorly to expose the tibial insertion of the superficial medial ligament, which lies deep and distal to the anterior edge of the sartorius. Note that the ligament inserts some 6 to 7 cm below the joint line, not close to it.
• Apply gentle traction to the superficial medial ligament to reveal its point of injury. Alternatively, apply a strong outward force to the knee, which will make obvious the site of the ligamentous disruption.
• Make a longitudinal medial parapatellar incision to gain access to the inside of the front of the joint.
• To avoid damage to the underlying medial meniscus, begin the incision well above the joint line and cut down carefully.

2. Posterior to the Superficial Medial Ligament:

The posterior approach exposes the posterior third of the meniscus and the posteromedial corner of the knee.

• Incise the fascia along the anterior border of the sartorius muscle in the same way as for the anterior approach.
• Retract the muscle posteriorly, together with the semitendinosus and gracilis muscles.
• In cases of damage to the posteromedial joint capsule, the back of the medial femoral condyle usually will be seen, with its underlying meniscus visible through the torn posteromedial joint capsule.
• If the capsule is intact, expose the posteromedial corner of the joint by separating the medial head of the gastrocnemius muscle from the semimembranosus muscle. Although both muscles are supplied by the tibial nerve, this intermuscular plane is a safe area for dissection, because the semimembranosus receives its nerve supply well proximal to the approach and the gastrocnemius receives it well distal.
• Finally, separate the medial head of the gastrocnemius muscle from the posterior capsule of the knee joint almost to the midline by blunt dissection.
• Full exposure allows the posteromedial corner of the capsule to be inspected for damage.
• A second arthrotomy posterior to the superficial medial ligament (the tibial collateral ligament) permits inspection or treatment of posterior intraarticular or periarticular pathology. Repair of the posteromedial comer of the joint also is possible.

Approach Extension

• The medial approach to knee joint cannot be extended usefully in either direction .

Dangers

The structures at risk during medial approach to knee joint include:

1. Infrapatellar branch of the saphenous nerve: It crosses transversely across operative field, and usually sacrificed and should be buried in fat to prevent neuroma.
2. Saphenous vein: it’s located between sartorius and gracilis muscles.
3. Medial inferior genicular artery: it may be damaged as medial head of gastrocnemius is lifted off tibia.
4. Popliteal artery: it lies along midline posterior joint capsule adjacent to medial head of gastrocnemius.

References

• Surgical Exposures in Orthopaedics book – 4th Edition

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