Tips for all-epiphyseal over-the-top ACL reconstruction in pediatric patients
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The incidence of pediatric knee injuries has been increasing in the last several years due to increased sports participation; in particular, the ACL is the most commonly injured knee ligament.
Over time, treatment strategies of pediatric ACL injuries have changed from conservative to early surgical treatment. Indeed, it has been shown that not treating an unstable knee leads to a higher prevalence of meniscal and chondral injuries. The main problem with early treatment is possible physeal disruption, which may impair bone growth.
Source: Silvia Bassini
To avoid this, several surgical techniques have been described, including physeal-sparing (extra-physeal or all-epiphyseal) and trans-physeal (partial or complete) techniques. The procedure developed by Maurilio Marcacci, MD, and Stefano Zaffagnini, MD, combines an all-epiphyseal intra-articular reconstruction with the addition of a lateral extra-articular tenodesis.
Surgical technique, graft harvesting
The patient is placed supine on the operating table and a pneumatic tourniquet is used. Under arthroscopic control, chondral and meniscal treatments are performed as needed. Next, the tibial ACL footprint and the intercondylar notch are prepared with a motorized shaver. It is essential to carefully remove all soft tissues in the posterior part of the roof as it may cause impingement with the graft.
The patient’s limb is positioned in the Figure four position, and an oblique incision of about 2 cm to 3 cm is made at the anteromedial aspect of the proximal tibia over the location of the pes anserinus. The subcutaneous tissue is dissected and then the fascial incision is made parallel to the orientation of the tendons. Special care should be taken to avoid the infrapatellar branches of the saphenous nerve.
The sartorius tendon is retracted superiorly, and the gracilis and semitendinosus tendons are meticulously separated from the surrounding soft tissue. Dissection scissors are used to isolate tendons from fascial adhesions to allow complete mobilization and avoid the “killer loop,” which can result in an incomplete tendon harvest. The superficial medial collateral ligament lies deep to the expansion of pes anserinus and should not be confused with it.
The tendons are then stripped separately with a blunt tendon stripper while maintaining firm tension on the tendon distally and with the knee in flexion at about 70°. Extreme caution is required to try to achieve maximum tendon length. The distal attachment of the tendons is dissected up to the tibial surface to gain an additional 1 cm to 2 cm in length. The tendons are not detached from the tibia to maintain the neurovascular supply, enhancing graft maturation and mechanical properties in the early phase. The harvested tendons are sutured together with nonabsorbable #2 stitches.
All-epiphyseal tibial tunnel
Special considerations are made to avoid physeal disruption while drilling the tibial tunnel, which is horizontally oriented and should not cross the physis. Under fluoroscopic control, the epiphyseal plate of the tibia is visualized together with the optimal entry point of the tibial tunnel, which is usually a few centimeters proximal and about 1 cm medial from the sampling site (Figures 1a and 1b).
A vertical incision is made, and the tibia is internally rotated. The guide pin is advanced through the tibia aiming at the ACL anatomical footprint under arthroscopic visualization. Then the tunnel is over-reamed with a 6-mm to 7-mm drill, according to the graft size.
A shaver is used to remove debris and smooth the edges of the tibial tunnel. A wire loop passer is introduced into the tibial tunnel into the notch and, under arthroscopic visualization, is retrieved through the anteromedial portal.
Over-the-top position
The knee is placed on the operating table at 90° of flexion. A 3-cm to 4-cm incision is performed superolterally, proximal to the lateral femoral epicondyle. The iliotibial band is split in the posterior third and retracted anteriorly. With electrocautery, the lateral portion of the thigh is dissected and the lateral intermuscular septum is reached. This septum inserts into the lateral femoral condyle and divides the vastus lateralis superiorly from the proximal portion of the gastrocnemius inferiorly.
Once the lateral intermuscular septum has been identified, the posterior portion of the capsule can be reached over these structures. The correct position of the over-the-top technique is found by palpating the posterior tubercle of the lateral femoral condyle with a finger. This maneuver allows the surgeon to protect the posterior neurovascular structures.
Graft passage, femoral fixation
A curved Kelly clamp is introduced into the joint via the anteromedial portal. Its tip is placed against the posterior portion of the capsule as proximal as possible. Once the clamp can be palpated from the lateral incision of the femur, posterior to the intermuscular septum, it is pushed through the thin layer of the capsule until it reaches the previously prepared posterior space.
A suture loop is placed into the tip of the clamp, dragged anteriorly through the anteromedial portal and inserted into the metal wire loop previously inserted in the portal. The wire is drawn through the tibial tunnel, thereby shuttling the suture through the tibial tunnel and out of the tibial incision. Using Klemmer forceps, the wire is dragged from the tibial tunnel incision to the tibial sampling incision (Figure 2). Using the shuttle suture loop, the stitches on the free end of the graft are dragged below the soft tissue to the tibial tunnel incision, in the tibial tunnel, into the joint and exiting posteriorly from the lateral aspect of the femur.
The graft is tensioned with the knee at 70° with the foot neutrally rotated and about 10 knee flexion-extension cycles are performed. A posterior drawer maneuver is performed, then the graft is fixed under fluoroscopic control to the lateral femoral cortex with two 6-mm staples, proximal to the superolateral geniculate artery, which is a landmark for the growth plate of the femur.
Lateral extra-articular tenodesis
A 1-cm skin incision is performed just below Gerdy’s tubercle. A Kelly clamp is inserted into this incision between the fascia and the lateral collateral ligament, bringing the tip out of the lateral incision of the thigh. The remaining portion of the graft is dragged inferiorly with the Kelly clamp and pulled out of the incision on Gerdy’s tubercle.
The graft is tensioned, and the isometric point is identified through flexion-extension cycles of the knee (Figure 3). The graft is fixed below Gerdy’s tubercle with one 6-mm staple under fluoroscopic control with the knee at 70° and neutral rotation of the foot (Figures 4a to 4d). The iliotibial tract defect is closed, as opposed to the fascia over the pes anserinus, to avoid compartment syndrome.
Postoperative protocol
A brace is not routinely used postoperatively. From the first day after surgery, passive range of motion exercises, quadriceps activation exercises, extended leg raises and prone hamstring stretching exercises are started. Progressive loading is allowed to reach full weight-bearing at about 3 weeks. At 15 days postoperatively, after the skin sutures are removed, rehabilitation in water and recovery of the active range of motion is initiated.
Stationary bike and proprioception exercises are started 1 month after surgery, and running is reintroduced at 3 to 4 months. At 6 months, sport-specific rehabilitation begins. Return to sport should be no earlier than 12 months. Rehabilitation is best performed under the supervision of a physical therapist. Ultimately, the decision to return to sport is the surgeon’s responsibility. Anti-thromboembolic prophylaxis is not recommended if there are no associated risk factors, such as obesity, birth control medicaton or a history of hypercoagulation condition. An MRI of the knee is performed 6 months after surgery to document the condition of the reconstruction, as well as other soft tissues involved in the injury or procedure (Figure 5).
- References:
- Funahashi KM, et al. Am J Sports Med. 2014;doi:10.1177/0363546514525584.
- Marcacci M, et al. Knee Surg Sports Traumatol Arthrosc. 1998;doi:10.1007/s001670050075.
- Moksnes H, et al. Knee Surg Sports Traumatol Arthrosc. 2016;doi:10.1007/s00167-015-3746-x.
- Pierce TP, et al. Am J Sports Med. 2017;doi:10.1177/0363546516638079.
- Roberti di Sarsina T, et al. Knee Surg Sports Traumatol Arthrosc. 2019;doi:10.1007/s00167-018-5132-y.
- Vavken P, et al. J Pediatr Orthop. 2018;doi:10.1097/BPO.0000000000000777.
- Yoo WJ, et al. J Pediatr Orthop. 2011;doi:10.1097/BPO.0b013e3182210952.
- Zaffagnini S, et al. Clin Anat. 2003;doi:10.1002/ca.10073.
- Zaffagnini S, et al. J Exp Orthop. 2023;doi:10.1186/s40634-023-00599-8.
- For more information:
- Alberto Grassi, MD; Gian Andrea Lucidi; Nicolò Maitan, MD; and Stefano Zaffagnini, MD, can be reached at the University of Bologna in Bologna, Italy. Grassi’s email: alberto.grassi@ior.it. Lucidi’s email: gianandrea.lucidi@ior.it. Maitan’s email: nicolo.maitan@ior.it. Zaffagnini’s email: stefano.zaffagnini@unibo.it.
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