[Anterior cruciate ligament reconstruction with semitendinosus tendon in children].

OBJECTIVE: To present the technique of arthroscopy-assisted anterior cruciate ligament (ACL) reconstruction in children with complete ACL rupture.

INDICATIONS: The indications for surgery are intraligamentous ruptures of the ACL with persistent signs and symptoms due to instability in spite of a minimum 6-month trial with conservative management and reduction of sports activities. Other decision-making factors for surgery include secondary injuries to the menisci or limitation of daily activities due to the instability produced by the ACL rupture. The indication for surgical intervention has to be judged individually and carefully in younger children.

CONTRAINDICATIONS: Poor compliance on the part of the patient to participate in postoperative rehabilitation. Overexpectations regarding the surgical outcome (ability to participate in professional sports without limitations). Younger age of the patient (Tanner stage 2 or younger maturity), without trial of conservative treatment over a period of 6 months. ACL rupture at the bone-ligament region (tibial or femoral), partial rupture or lengthening of the ACL without rupture; in these instances, the instability may improve with growth.

SURGICAL TECHNIQUE: Diagnostic arthroscopy to evaluate the knee joint and to identify associated or secondary injuries to the menisci and articular cartilage. If possible, these injuries should be addressed in the same surgical session. Preparation and stripping of the semitendinosus tendon using a tendon stripper. The technique used is transepiphyseal with extraosseous fixation. Depending on the thickness, the semitendinosus tendon is either tripled or quadrupled and prepared for transplantation. Single-canal technique. The diameter of the canal has to be selected depending on the size of the child's knee (usually between 6-8 mm). The tendon transplant is placed such that the canal is also filled with the tendon in the epiphyseal part (tendon transplant length usually 7 cm). Tibial canal entry medial to the tibial tuberosity, entering the joint at the level of the anterior horn of lateral meniscus in the intercondylar notch. Optimal positioning confirmed by an intraoperative negative impingement test of the guiding pin before drilling. Femoral canal entry placed at the 10:00-10:30 o'clock position on the right side, and 01:30-02:00 o'clock position on the left side. Care must be taken to avoid injury to the perichondral ring. In younger children (Tanner stage 3 or lower), avoidance of fixation material transfixing the epiphysis - femoral fixation performed using endobutton and tibial fixation with the Suture-disc. In older children (Tanner stage 4 or above) alternative fixation methods are possible (interference screw). The fixation of the ACL tendon transplant is such that reconstruction is in minimal tension in 30 degrees flexion.

POSTOPERATIVE MANAGEMENT: Postoperative treatment regimen in the first 6 weeks after surgery depends on the extent of additive surgeries (menisci, chondral injuries) performed in the same sitting. In the absence of associated injuries, weight bearing is gradually increased with the aim of achieving full weight bearing at the end of the 1st postoperative week. In case of additional meniscal sutures, knee flexion is restricted to 60 degrees maximum and non-weight bearing for 4 weeks is advised. Postoperative mobilization is performed using an adjustable knee orthesis. Between 4-6 weeks postoperatively, the permitted flexion is gradually increased to a maximum of 90 degrees and partial weight bearing is started. Full weight bearing and free movements with muscle training are started after 6 weeks. Avoidance of weight transmission on the flexed and rotated knee until 12 weeks postoperatively. Start with sports activities under supervision after 6 months, trial with professional sports activities after 9 months.

RESULTS: 57 children with remaining growth potential around the knee underwent ACL reconstruction using the semitendinosus tendon at the Pediatric Orthopedic Unit, Department of Pediatric Surgery, Graz, Austria, between 2002-2007. 45 patients received ACL reconstruction with associated meniscal injuries. The described endobutton technique for fixation of the transplant has been performed since 2006. As the patients are under follow-up, the long-term effects of this technique on growth around the knee are, to date, not known. 30 patients were operated before 2006 using the bioresorbable interference screw for fixation by ACL reconstruction with the semtendinosus tendon. All these patients were at Tanner stage 4 or older. 15 of these cases were evaluated after completion of growth, and all showed a good to excellent outcome in Tegner, Lysholm and IKDC (International Knee Documentation Committee) Scores without any growth disturbances.