PROCEDURE 37

Transphyseal ACL Reconstruction in Skeletally Immature Patients Using Autogenous Hamstring Tendon

Mininder S. Kocher, Craig J. Finlayson and Adam Nasreddine

Indications

 Adolescent patient with significant growth remaining (Tanner stage 3 or greater) with a complete anterior cruciate ligament (ACL) tear and functional instability (Fig. 1)

 Adolescent patient with significant growth remaining with a partial ACL tear that has failed nonoperative treatment

 Adolescent patient with significant growth remaining with an ACL tear and other injuries such as meniscal tears or chondral injury

 Adolescent patient with significant growth remaining with congenital ACL insufficiency and symptomatic instability despite bracing

Pitfalls

• Delaying ACL reconstruction by 3 months is recommended in the case of a meniscal tear that requires extensive repair in order to protect the meniscal repair from early mobilization prescribed by ACL reconstruction.

• Patients must be emotionally mature enough to actively participate in the extensive rehabilitation required after ACL reconstruction.

Examination/Imaging

 An examination under anesthesia is performed.

 Range of motion is checked.

• Normal range can have slight hyperextension up to 130° of flexion.

 Varus/valgus stress test

• This test is done at both 0° and 30° of flexion.

• The surgeon must determine if there is increased laxity of either the medial or lateral collateral ligament.

 Lachman test

• With the knee at 30° of flexion, the tibia is translated anteriorly without a solid endpoint.

• The patient is re-evaluated at the end of the case for comparison.

 Pivot shift test

• The knee is taken from extension to flexion while placing valgus stress on the knee and internally rotating the tibia.

• The surgeon should feel for a gliding or shifting sensation of the tibiofemoral joint.

 Tanner stage

• Staging is done by assessing for the presence and distribution of pubic hair and for breast/testicular development.

 Plain radiographs

• Posteroanterior (PA), lateral, Merchant’s, and tunnel views are obtained before surgery to evaluate for any bony abnormalities.

• Radiographs allow for initial evaluation of the physis before surgery has been completed.

• A anteroposterior (AP) radiograph of the left hand and wrist is obtained to determine bone age.

 Magnetic resonance imaging (MRI) (Fig. 2)

• MRI scans are evaluated for edema patterns consistent with recent ACL tear: lateral femoral condyle, posterolateral tibial plateau.

• Scans are also evaluated for other injuries, such as chondral or meniscal injuries.

• MRI allows for preoperative planning.

Treatment Options

• Conservative treatment with activity modification and protective bracing

Surgical Anatomy

 Anterior cruciate ligament

• The ACL orginates on the lateral wall of the intercondylar notch of the femur.

• It inserts on the anterior tibial spine.

 Proximal tibial and distal femoral physes

• The origin of the ACL is approximately 3–5 mm distal to the femoral physis in adolescents.

 Hamstring tendons (gracilis and semitendinosus)

• These tendons are palpable at their insertion at the pes anserinus on the medial surface of the proximal tibia.

• They lie deep to the sartorius fascia.

 Saphenous nerve

• This nerve runs along the posterior border of the sartorius posterior to the pes anserinus.

Positioning

 The patient is positioned supine.

 A tourniquet is placed on the thigh of the operative leg.

 The leg, including the foot, is prepped sterilely.

Pearls

• Apply the tourniquet and drapes as proximally as possible to allow passage of the femoral guide pin.

• Ensure that the knee can be flexed to at least 90° to facilitate proper femoral tunnel placement.

Pitfalls

• Inability to flex the knee to at least 90° may result in a vertical femoral tunnel.

Equipment

• A lateral post or leg holder may be used.

Portals/Exposures

 Two standard arthroscopic portals are used (Fig. 3).

• The anterolateral portal is the primary viewing portal.

• The anteromedial portal is the primary working portal.

 Hamstring harvest/tibial tunnel

• A 4-cm incision is made over the palpable pes anserinus on the proximal medial tibia (see Fig. 3).

• Dissection is carried down to the level of the sartorius fascia.

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