Approach for Medial Meniscectomy
The approach for medial meniscectomy14 was a common formal incision for the knee. It is quite flexible, with several acceptable locations for incision and many different ways to position the patient. Some surgeons advocate a transverse skin incision over the joint line; although this limits the view of the knee, it provides better access to the meniscus itself. Others prefer longitudinal or oblique incisions, which offer a better view of such other intra-articular structures as the cruciate ligaments. Although operative arthroscopy has almost abolished the need for this approach, it remains a useful one in those parts of the world where arthroscopy is not available.
The uses of the anteromedial approach include the following:
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Medial meniscectomy
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Partial meniscectomy
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Removal of loose bodies
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Removal of foreign bodies
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Treatment of osteochondritis of the medial femoral condyle15
Position of the Patient
Arrange the patient in a supine position on the operating table. Place a sandbag under the affected thigh, taking care that it is not directly beneath the popliteal fossa, where it will compress the popliteal artery and posterior joint capsule against the back of the femur and tibia, increasing the risk of accidental injury during excision of the posterior third of the meniscus (Fig. 10-15). Remove the end of the table so that the knee can be flexed beyond a right angle.
This position requires good lighting so that the meniscus can be seen during surgery. The light must be adjusted continually to keep it shining directly into the depths of the wound. A headlamp is the best light source.
Exsanguinate the limb by elevating it for 2 to 5 minutes or by applying
a soft rubber bandage. Then, inflate a tourniquet.
Landmarks and Incision
Landmarks
The medial joint line must be accurately identified because incisions can easily be made too high. To allow the line to be palpated with certainty flex and extend the knee.
Locate the inferomedial corner of the patella.
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Figure 10-15 A: Position of the patient for medial meniscectomy. B: Improper placement of the sandbag pushes the popliteal artery against the posterior joint capsule. C: Proper placement of the sandbag under the affected thigh.
Incision
Begin the incision at the inferomedial corner of the patella. Angle it inferiorly and posteriorly, ending about 1 cm below the joint line. Incisions
Internervous Plane
There is no internervous plane in this approach because the deep incision is made through the medial patellar retinaculum and joint capsule.
Superficial Surgical Dissection
Deepen the wound in line with the skin incision down to the anteromedial aspect of the joint capsule, the true joint capsule, which is reinforced by the medial retinaculum of the patella (Fig. 10-17). Incise the capsule in line with the skin incision, which also is in line with the capsular fibers (Fig. 10-18).
Deep Surgical Dissection
Open the synovium, together with the extrasynovial fat, well above the joint line to gain access to the anteromedial portion of the joint (Fig. 10-19). Opening the joint above the joint line avoids damage to the intrasynovial fat pad, medial meniscus, and coronary ligament (Figs. 10-20 and 10-21).
Dang
Nerves
The infrapatellar branch of the saphenous nerve may be cut if the incision is extended farther inferiorly than 1 cm below the joint line (see Fig. 10-16).
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Figure 10-16 Incision for anteromedial approach for medial meniscectomy.
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Figure 10-17 Incise down to the anteromedial aspect of the joint capsule.
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Figure 10-18 Incise the joint capsule in line with the incision to reveal the extrasynovial fat.
Vessels
Because the popliteal artery is immediately behind the posterior joint capsule, any injury to the posterior joint capsule may damage the artery. If the knee is flexed, the posterior joint capsule falls away from the tibia and femur, taking the artery with it. A sandbag placed directly under the
popliteal fossa prevents the capsule from moving posteriorly and must be avoided at all costs (see Fig. 10-15B,C).
Muscles and Ligaments
The coronary ligament (the meniscotibial element of the deep medial ligament) connects the periphery of the meniscus with the joint capsule and tibia, and may be damaged if the incision through the synovium is made at the joint line (see Figs. 10-33 and 10-34).
Incisions made too far posteriorly may cut the superficial medial ligament (the tibial collateral ligament) as it runs from the medial epicondyle of the femur to its insertion on the tibia under cover of the pes anserinus (see Figs. 10-27 and 10-28).
Special Structures
The fat pad occupies varying amounts of the anterior portion of the knee joint and should not be damaged. Damage may produce adhesions within the joint and, in theory, can interfere with the blood supply to the patella (see Fig. 10-12).
The medial meniscus may be incised accidentally during the opening of the synovium unless the knee joint is entered well above the joint line.
How to Enlarge the Approach
Local Measures
Three factors may improve the exposure offered by this approach:
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Figure 10-19 Incise the synovium to gain access to the joint.
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Figure 10-20 Open the joint capsule and synovium to the joint line to prevent
damage to the meniscus and synovial fat pad.
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Figure 10-21 Flex the knee and use retractors to gain further access to the meniscus.
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Retraction. Retractors must be positioned and repositioned carefully to ensure the best possible view of the intra-articular structures.
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Position of light. Light should shine directly into the wound, usually from over the surgeon’s shoulder. Constant readjustment is necessary, and the use of a headlamp is invaluable.
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A valgus stress will open up the medial side of the joint. Flexion of the knee allows better access to the back of the medial side of the joint. If the posterior horn of the medial meniscus must be seen, however, a better view is obtained by putting the leg into full extension and
applying a distraction and valgus force. However, visualization of the peripheral parts of the posterior horn is always very limited in this surgical approach when compared to arthroscopic approaches.
Extensile Measures
Posterior Extension. The dissection is limited posteriorly by the superficial medial ligament, which crosses the joint just in front of the midpoint of the femur. For better access to the posterior half of the joint, a second incision must be made behind this ligament. This is usually only required for excision of a retained posterior horn.
Insert a blunt instrument into the joint and push it slowly backwards, running along the inside the knee at the level of the joint itself. As the instrument is pushed backwards apply some outward pressure. The superficial medial ligament will be sensed as a firm structure beneath the tip of the instrument. As the instrument is passed posteriorly there will be a sudden give in the resistance to outward pressure corresponding to the posterior edge of the superficial medial ligament (Fig. 10-22). At that point, make a second longitudinal posterior incision through the skin and knee joint capsule (Fig. 10-23).
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Figure 10-22 Insert a blunt instrument into the joint, and push it backward along the inside of the medial joint capsule. Palpate posteriorly until the instrument can be felt beneath the skin.
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Figure 10-23 Make a second longitudinal posterior incision to enter the posteromedial aspect of the joint.
Superior Extension. To extend the incision superiorly, continue incising the skin along the medial border of the patella. Then, incise the medial patellar retinaculum and the underlying joint capsule in the same line to reach the back of the patella. Further superior extension exposes the suprapatellar pouch, which is a frequent site of loose bodies in the knee.
The incision may be extended still farther proximally in the muscular plane between the vastus medialis and rectus femoris muscles, exposing the distal two-thirds of the femur.
Inferior Extension. Inferior extension can cut the infrapatellar branch
of the saphenous nerve and is not recommended.
