Operative Techniques in Orthopaedic Surgery (4 Volume Set) 1st Edition

131. Anterior Cruciate Ligament Reconstruction in the Skeletally Immature Patient

J. Todd R. Lawrence and Mininder S. Kocher

DEFINITION

images Skeletally immature patients have open growth plates, or physes, and thus have growth potential remaining.

images Intrasubstance anterior cruciate ligament (ACL) injuries were once considered rare in this population, with tibial eminence avulsion fractures considered the pediatric ACL injury equivalent.11 However, intrasubstance ACL injuries in children and adolescents are being seen with increasing frequency and result in an “ACL-deficient knee” as in adult patients.

images ACL deficiency in the skeletally immature patient usually results in an unstable knee at risk for further injury and accelerated degeneration.

images Conventional surgical reconstruction techniques risk potential iatrogenic growth disturbance due to physeal violation, and thus special consideration must be given to this patient population.9

images The physiologic age of the patient reflects the amount of remaining growth potential and heavily influences the treatment options.

ANATOMY

images The ACL originates from a semicircular area on the posterior portion of the medial aspect of the lateral femoral condyle and courses obliquely to the anteromedial aspect of the tibial plateau at the anterior tibial eminence (or spine).

images The primary role of the ACL is to resist anterior translocation and rotation of the tibia on the femur.

images The ligament is composed of two anatomically and biomechanically distinct bundles, the anteromedial and the posterolateral bundles.

images The anteromedial bundle is more anterior and vertical in orientation. It largely resists anterior translation and tightens in the last 30 degrees of extension.

images The posterolateral bundle is more posterior and oblique in orientation. It is more isometric and plays a greater role in rotational control.

images Not all skeletally immature patients are the same. Some have a tremendous amount of growth remaining, while others are essentially done growing.

images Most of the longitudinal growth of the lower extremities comes from the distal femur and the proximal tibia. The tibial physis can be as close as 15 to 20 mm to the tibial spine. The femoral physis comes within millimeters of the femoral attachment of the ACL at the most posterior aspect of its insertion (FIG 1).

PATHOGENESIS

images The etiology of ACL injury in skeletally immature patients is similar to that in the adult population. It is usually due to a noncontact injury involving a cutting, pivoting, or rapid deceleration maneuver.

images Patients often report hearing a “pop” followed by swelling of the knee. ACL injury has been reported in up to 65% of pediatric patients with acute traumatic hemarthroses.13

images The “shift” that occurs with the ACL-deficient knee at the time of injury causes an impaction injury on the posterior aspect of the tibial plateau against the distal femur at the sulcus terminalis as the tibia translates anteriorly on the femur. Characteristic bone bruises in this location on MRI are pathognomonic for ACL injury (FIG 2).

images Ligamentous, meniscal, and chondral injuries are commonly associated with ACL injury.

images The medial collateral ligament is commonly injured with the ACL.

images The posterolateral corner is less often injured with the ACL but is a common cause of failure of ACL reconstruction if it is not addressed as well.

images Tears of the lateral meniscus are associated with acute tears of the ACL.

images The posterior horn of the medial meniscus is a secondary restraint to anterior translation of the tibia. In the chronically ACL-deficient knee the posterior horn of the medial meniscus assumes a greater role in preventing anterior translation and is thus at increased risk of injury.

NATURAL HISTORY

images Partial tears may be successfully managed nonoperatively in some patients.8

images

FIG 1 • Sagittal MRI demonstrating the relationship of the anterior cruciate ligament to the distal femoral and proximal tibial physes. (From Kocher MS, Garg S, Micheli LJ. Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents: surgical technique. J Bone Joint Surg Am 2006;88A[Suppl 1 Pt 2]:283–293.)

images

FIG 2 • Sagittal MRI through the lateral aspect of the knee demonstrating characteristic bone bruise pattern for an acute anterior cruciate ligament injury (thin arrow). Note increased signal on the posterior aspect of the lateral tibial plateau and the distal aspect of the femur at the sulcus terminalis (thick arrow).

images Complete tears in skeletally immature patients generally have a poor prognosis, with near-universal recurrent instability leading to further meniscal and chondral injury.1,10

images Over half of patients show evidence of early degenerative changes 4 to 5 years after their injury.10

images Patients who have a greater amount of instability, as measured objectively with KT-1000 arthrometry, or pursue higher-level cutting and jumping sports, are at greater risk for recurrent injury.3

images ACL reconstruction can reduce the risk of recurrent meniscal and chondral injury. However, how this influences the risk of developing degenerative joint disease is not clear at this time.

PATIENT HISTORY AND PHYSICAL FINDINGS

images Adolescents are notoriously bad historians, but every attempt should be made to garner an appreciation for the mechanism of injury, a history of acute or recurrent effusions, and a sense of instability with activities or mechanical symptoms.

images Physiologic age should be established informally in the office using the Tanner staging system.14 This can be confirmed in the operating room after the induction of anesthesia. Skeletal age can be determined via hand and wrist radiographs per the method of Greulich and Pyle.4

images A complete examination of the knee should be performed. Particular attention should be given to evaluating the knee for associated pathology.

images Patella ballottement and fluid wave test should be done to evaluate for the presence of an effusion.

images Range of motion (ROM) is important to assess because regaining full ROM before ACL reconstruction may be critical to prevent postoperative arthrofibrosis. Loss of extension should alert the clinician to the possibility of a displaced bucket-handle tear or preoperative arthrofibrosis. Loss of flexion may be due to pain secondary to a tense effusion.

images Tenderness to palpation should be assessed and localized specifically as it can greatly direct the diagnosis of related injuries.

images Tenderness to palpation along the joint line, particularly the posterior aspect of the joint line, should alert the clinician to the possibility of a meniscal tear. Pain or palpable popping with provocative maneuvers, such as McMurray, Apley compression, or duck walk, will help to confirm this finding.

images Pain along the course of or at the femoral or tibial insertion points for the collateral ligaments should alert the clinician to the possibility of a collateral ligament tear.

images Pain at the physis should prompt an investigation for a physeal injury, although in our experience this is not commonly associated with complete ACL injuries.

images Tenderness along the medial retinaculum or the course of the medial patellofemoral ligament can indicate an acute patellar dislocation that reduced spontaneously.

images Ligamentous evaluation should include the anterior and posterior cruciate ligaments, the medial and lateral collateral ligaments, and the posterolateral corner.

images Skeletally immature athletes have a greater degree of physiologic laxity than adult athletes, and as such a comparison should always be made to the uninjured knee.

images Evaluation of the ACL is best done with the Lachman test in the cooperative patient. In the patient who voluntarily or involuntarily guards against traditional Lachman testing, the prone Lachman may encourage relaxation and give a more reliable examination.

images Pivot shift testing may be performed in the office but is usually not well tolerated by pediatric patients. It should be performed in the operating room as part of the preoperative evaluation of every patient.

images The posterior cruciate ligament should be evaluated using the posterior drawer test. The relative starting point should always be assessed first and compared to the contralateral side. The utility of posterior drawer stress radiographs is unclear at this time. Injuries of grade II and above should alert the clinician to the possibility of an associated posterolateral corner injury.

images Medial and lateral collateral ligament injuries are assessed through stress opening with valgus and varus stress at 0 and 30 degrees of knee flexion. In the pediatric patient, opening with varus and valgus stress can be due to physeal injuries, and the clinician should always be vigilant for this.

images Evaluation of the posterolateral corner is best done with the dial test. The posterolateral drawer and the external rotation recurvatum tests are also useful for evaluating posterolateral corner injuries.

images Evaluation for patellar instability with apprehension testing should be performed.

images Evaluation of quadriceps bulk and strength is important for postoperative recovery.

IMAGING AND OTHER DIAGNOSTIC STUDIES

images All pediatric patients with a complaint of knee pain should receive an initial plain radiographic evaluation including AP, lateral, and patellar views. Special attention should be given to evaluate for physeal injuries as well as other injuries on the differential diagnosis.

images AP and frog-lateral plain radiographs of the hip should be considered in the evaluation of all pediatric patients with complaints of knee pain.

images Overall varus and valgus malalignment, if present clinically, should be evaluated with full-length, hip-to-ankle radiographs.

images MRI is the diagnostic imaging test of choice for further evaluation of ACL tears in the skeletally immature patient. However, it is significantly less sensitive and specific for diagnosing ACL injuries in this population compared with the adult population.5 Findings on MRI signifying an ACL tear include a discontinuity in the fibers on the ACL and a characteristic bone bruise pattern on the distal femur and the posterior tibial plateau of the lateral hemi-joint.

images MRI in the pediatric population also has a high falsepositive rate for meniscal tears. This is likely due to the increased vascularity of the meniscus, which is often interpreted as intrasubstance degeneration or a tear of the meniscus.5

DIFFERENTIAL DIAGNOSIS

images Tibial eminence (spine) fracture

images Other intra-articular or physeal fracture

images Patellar dislocation

images Meniscal tear

images Posterior cruciate ligament tear

images Medial or lateral collateral tear

images Posterolateral corner injury

images Physiologic laxity

images Hip etiology

NONOPERATIVE MANAGEMENT

images Partial or incomplete tears can be successfully managed nonoperatively in some patients if clinical and functional stability is possible. The following criteria have been shown to be associated with successful nonoperative treatment of partial tears:8

images Tears of less than 50% of the ligament

images Relative preservation of the posterolateral bundle

images Age less than 14 years

images Normal or near-normal Lachman or pivot shift test

images Up to a third of patients may require subsequent reconstruction and should be made aware of that risk at the onset of treatment.

images Successful treatment based on the above criteria includes.

images A hinged knee brace is worn for 12 weeks.

images Touch-down weight bearing is maintained for 6 to 8 weeks.

images Passive terminal extension is restricted for the first 6 weeks.

images Active terminal extension is restricted for 12 weeks.

images Physical therapy emphasizes hamstring muscle strengthening.

images Return to sports and active play is permitted at 3 months with the use of a functional knee brace for 2 years for cutting and pivoting activities.

images Nonoperative management of complete tears in skeletally immature patients generally has a poor prognosis.

images For prepubescent patients with a complete ACL tear and without concurrent chondral injury requiring stabilization or meniscal injury requiring repair, we favor attempted nonoperative treatment with activity modification, functional bracing, and continued rehabilitation.

images In our experience, compliance with activity modification and brace use and effectiveness limits the success of this treatment.

images Delay in surgical stabilization can lead to further meniscal and chondral injury due to recurrent instability.

images Although results of nonoperative management are generally poor, the risk of further intra-articular injury by waiting until skeletal maturity to undergo reconstruction must be weighed against the risk of growth disturbance with early reconstruction.

images Some patients are able to cope with their ACL insufficiency or modify their activities, allowing for further growth and aging such that an adolescent-type reconstruction can be performed with transphyseal hamstrings tendons in a more anatomic manner.

images For prepubescent patients with recurrent instability despite the above treatment, reconstruction is indicated.

images For adolescent patients with growth remaining who have a complete ACL tear, we do not advocate initial nonoperative treatment since the risk of functional instability with injury to the meniscal and articular cartilage is high, the risk and consequences of growth disturbance from ACL reconstruction are less, and the transphyseal technique is an anatomic reconstruction.

SURGICAL MANAGEMENT

images Conventional adult ACL reconstruction techniques risk potential iatrogenic growth disturbance due to physeal violation, and cases of growth disturbance have been reported in animal models and clinical series.9

images The following principles should be applied when considering any reconstructive strategy:

images Hard fixation, such as with an interference screw, or any bone crossing the physis, has a high risk of inducing a growth disturbance.

images A tensioned soft tissue graft in a bone tunnel across the physis can also induce a growth disturbance.

images The approach to ACL reconstruction in the skeletally immature patient should be based on physiologic age (FIG 3).

images A variety of reconstructive techniques have been used, including physeal-sparing, partial transphyseal, and transphyseal methods using various grafts.

images In prepubescent patients with large amounts of growth potential remaining, we perform a physeal-sparing, combined intra-articular and extra-articular reconstruction using autogenous iliotibial band.

images Recognizing that the physeal-sparing reconstruction described here is nonanatomic, we counsel patients and families that revision reconstruction may be needed if recurrent instability develops, but that this procedure may temporize for further growth such that the patient may then undergo a more conventional reconstruction with drill holes.

images A variety of other physeal-sparing reconstructions have been described to avoid tunnels across either the distal femoral or proximal tibial physis, but they will not be described here.

images In adolescent patients with significant growth remaining, we perform transphyseal ACL reconstruction with autogenous hamstring tendons with fixation away from the physes.

images In adolescent patients approaching skeletal maturity, we perform conventional adult ACL reconstruction with interference screw fixation using either autogenous centralthird patellar tendon or autogenous hamstrings (see Chap. SM-10).

images In skeletally immature patients, as in adult patients, acute ACL reconstruction is not performed within the first 3 weeks after injury to minimize the risk of arthrofibrosis.

images Prereconstructive rehabilitation is performed to regain ROM, decrease swelling, and resolve the reflex inhibition of the quadriceps.

images

FIG 3 • Algorithm for management of complete anterior cruciate ligament injuries in skeletally immature patients.

images Skeletally immature patients must be emotionally mature enough to actively participate in the extensive rehabilitation required after ACL reconstruction.

Preoperative Planning

images All imaging studies, including plain radiographs and MRI, should be reviewed and associated injuries identified.

images In general, associated injuries, such as meniscal, articular cartilage, or other multiple ligament injuries, should be addressed at the time of ACL reconstruction. However, reconstruction may be staged in some cases, such as nonoperative treatment of a medial collateral ligament injury before ACL reconstruction.

images Consideration should be given to using pediatric anesthesia services, given the age of the patient.

images Tanner staging should be confirmed at the time of surgery after the induction of general anesthesia.

images A complete ligamentous knee examination, including Lachman, pivot shift, varus and valgus stress, posterior drawer, and dial tests, should be performed and the findings compared to the contralateral side to confirm the diagnosis.

Positioning

images For both procedures described here, the physeal-sparing combined intra-articular and extra-articular reconstruction with autogenous iliotibial band and the transphyseal reconstruction with autogenous hamstrings with metaphyseal fixation, positioning and setup are very similar.

images The procedure is performed under general anesthesia with overnight observation. Regional anesthesia can assist with pain relief but is not required. Local anesthesia with sedation may not be reliable in this population and has the potential for a paradoxical effect of sedation.

images The patient is placed supine on the operating room table and moved close to the operative side of the table such that the operative leg easily drapes over the edge of the table.

images A tourniquet is placed high about the upper thigh. It is routinely used during the physeal-sparing procedure but is not routinely used during the transphyseal technique.

images A side post is placed two fingerbreadths above the flexed knee as it drapes over the side of the bed. It is used in the “up” position for the diagnostic arthroscopy and dropped to the “down” position to provide a ledge for supporting the knee during the ACL reconstruction.

Approach

images The approach depends on the technique employed and the choice of graft.

images Autograft is preferred, but soft tissue allograft could be considered based on patient preference. Allograft would negate the need for hamstring harvest in the transphyseal reconstruction.

TECHNIQUES

PHYSEAL-SPARING, COMBINED INTRA-ARTICULAR AND EXTRAARTICULAR RECONSTRUCTION WITH AUTOGENOUS ILIOTIBIAL BAND IN PREPUBESCENT PATIENTS

Harvest of Iliotibial Band Graft

images  An incision of about 6 cm is made obliquely from the lateral joint line to the superior border of the iliotibial band.

images  Proximally, the iliotibial band is separated from subcutaneous tissue using a periosteal elevator under the skin of the lateral thigh.

images  The anterior and posterior borders of the iliotibial band are incised and the incisions carried proximally under the skin using curved meniscotomes (TECH FIG 1A).

images  The iliotibial band is detached proximally under the skin using a curved meniscotome or an open tendon stripper. Alternatively, a counter-incision can be made at the upper thigh to release the tendon.

images  Dissection is performed distally to separate the iliotibial band from the joint capsule and from the lateral patellar retinaculum (TECH FIG 1B).

images  The iliotibial band is left attached distally at the tubercle of Gerdy (TECH FIG 1C).

images  The free proximal end of the iliotibial band is tubularized with a no. 5 Ethibond whipstitch and wrapped in a moist sponge until needed later.

Arthroscopy

images  Diagnostic arthroscopy of the knee is performed through standard anterolateral viewing and anteromedial working portals.

images  Management of meniscal injury or chondral injury is performed if present.

images  The ACL remnant is excised with the use of biting instruments and the shaver.

images  The over-the-top position on the femur and the overthe-front position under the intermeniscal ligament are identified and cleared of excess tissue to allow passage of the graft.

images  Minimal notchplasty is performed to avoid iatrogenic injury to the perichondrial ring of the distal femoral physis, which is very close to the over-the-top position.2

Graft Passage

images  The free end of the iliotibial band graft is brought through the over-the-top position using a full-length clamp (TECH FIG 2A) or a two-incision rear-entry guide (TECH FIG 2B) and out the anteromedial portal (TECH FIG 2C,D).

images  A second incision of about 4.5 cm is made over the proximal medial tibia in the region of the pes anserinus insertion.

images  Dissection is carried through the subcutaneous tissue to the periosteum.

images  A curved clamp is placed from this incision into the joint under the intermeniscal ligament (TECH FIG 2E).

images  A small groove is made in the anteromedial proximal tibial epiphysis under the intermeniscal ligament using a curved rat-tail rasp to bring the tibial graft placement more posterior.

images  The free end of the graft is then brought through the joint, under the intermeniscal ligament in the anteromedial epiphyseal groove, and out the medial tibial incision (TECH FIG 2F).

Graft Fixation

images  Through the lateral incision, the iliotibial band graft is sutured near the over-the-top position to the intermuscular septum and the periosteum of the posterior lateral femoral condyle with the knee flexed 90 degrees, tension on the graft, and the foot externally rotated 30 degrees (TECH FIG 3A).

images  Fluoroscopic imaging is used to assess the location of the proximal tibial physis.

images  A longitudinal incision is made in the periosteum distal to the proximal tibial physis.

images

TECH FIG 1 • Harvest of iliotibial band graft for physeal-sparing anterior cruciate ligament reconstruction. The anterior and posterior aspects of the iliotibial band are identified through a laterally based incision at the knee. A. A meniscotome or an open tendon stripper is then used to harvest the proximal aspect of the graft. B. The graft is then freed distally. C. The free proximal aspect of the graft is tubularized and left attached distally to the tubercle of Gerdy. (A,B: From Kocher MS, Weiss JM. ACL reconstruction in the skeletally immature patient. In Tolo VT, Scaggs DL, eds. Master Techniques in Orthopaedic Surgery: Pediatrics. Philadelphia: Lippincott Williams & Wilkins, 2008:277–287.)

images

TECH FIG 2 • Graft passage for physeal-sparing anterior cruciate ligament reconstruction. A. The graft is brought through the knee in the over-the-top position using a full-length clamp introduced through the anteromedial portal and out the lateral incision. B. Alternatively, a two-incision rear-entry guide can be used. C,D. The lead sutures are used to bring the graft through the notch and out the anteromedial portal. E. After a rasp is used to create a groove in the anterior tibia, under the intermeniscal ligament, a curved clamp is placed under the intermeniscal ligament (F) and the graft is brought to the anterior aspect of the knee. (A,C,E,F: From Kocher MS, Weiss JM. ACL reconstruction in the skeletally immature patient. In Tolo VT, Scaggs DL, eds. Master Techniques in Orthopaedic Surgery: Pediatrics. Philadelphia: Lippincott Williams & Wilkins, 2008:277–287.)

images  The edges are gently elevated and a trough is made in the proximal tibial medial metaphyseal cortex.

images  The knee is flexed 20 degrees and tension applied to the graft.

images  The graft is sutured to the periosteum at the roughened margins with mattress sutures (TECH FIG 3B).

images  The knee is checked for stability to Lachman testing and ROM.

Wound Closure

images  The wounds are copiously irrigated.

images  The tourniquet is deflated and meticulous hemostasis is achieved.

images  The wounds are then closed in layers in a standard fashion.

images

TECH FIG 3 • Graft fixation for physeal-sparing anterior cruciate ligament reconstruction. A. With the knee flexed 90 degrees, tension on the graft, and the foot externally rotated 30 degrees, the graft is secured to the intermuscular septum and the periosteum of the posterior lateral femoral condyle near the over-the-top position. B. With the knee flexed to 20 degrees, the tensioned graft is secured to the periosteum at the roughened margins of a trough in the proximal tibia. Fluoroscopic imaging is used to ensure that the proximal tibial physis is not disturbed. (A: From Kocher MS, Weiss JM. ACL reconstruction in the skeletally immature patient. In Tolo VT, Scaggs DL, eds. Master techniques in orthopaedic surgery: pediatrics. Philadelphia: Lippincott Williams & Wilkins, 2008:277–287.)

TRANSPHYSEAL RECONSTRUCTION WITH AUTOGENOUS HAMSTRINGS WITH METAPHYSEAL FIXATION IN ADOLESCENT PATIENTS WITH GROWTH REMAINING

images  The transphyseal reconstruction is similar to the singlebundle ACL reconstruction technique.

images  The basic principles of graft harvest, notch preparation, tunnel placement, and tunnel creation are the same.

images  This technique uses an all-soft-tissue graft with metaphyseal fixation. We describe fixation with an EndoButton (Smith & Nephew Arthroscopy, Andover, MA) on the femoral side and an all-metaphyseal interference screw on the tibial side, but other all-metaphyseal options exist.

Harvest and Preparation of Autogenous Hamstrings Tendon Graft

images  Hamstrings are routinely harvested at the start of the case if the diagnosis is not in question. However, if the diagnosis is in doubt, arthroscopy can be performed first to confirm ACL tear.

images  The leg is placed in a slightly externally rotated position with the knee slightly bent.

images  A 4-cm incision is made over the palpable pes anserinus tendons on the medial side of the upper tibia.

images Dissection is carried through skin to expose the sartorius fascia.

images  The underlying gracilis (superior) and semitendinosus (inferior) tendons are identified by palpation.

images  A longitudinal incision is made in the flat sartorius fascia. The cordlike gracilis and semitendinosus tendons are identified on its deep surface.

images  The tendons are dissected free distally and their free ends whipstitched with no. 2 or no. 5 Ethibond suture.

images  They are dissected proximally using sharp and blunt dissection. Fibrous bands to the medial head of the gastrocnemius should be sought and must be completely released before proceeding with tendon stripping.

images  A closed tendon stripper is used to dissect the tendons free proximally. Firm, steady longitudinal retraction is placed on the tendons individually as the tendon stripper is gently and slowly advanced proximally collinear to the vector of pull of the tendon.

images Alternatively, the tendons can be left attached distally and an open tendon stripper used to release the tendons proximally.

images  The tendons are taken to the back table and excess muscle is removed by scraping with the side of a no. 15 blade or a Freer.

images  The ends are whipstitched with no. 2 or no. 5 Ethibond suture.

images  The tendons are folded over a closed loop EndoButton.

images  The graft diameter is sized and the graft is placed under tension with wet gauze around it.

Arthroscopy

images  Arthroscopy of the knee is then performed through standard anterolateral viewing and anteromedial working portals.

images  Management of meniscal injury or chondral injury is performed if present.

images  The ACL remnant is excised with the use of biting instruments and the shaver to reveal the anatomic footprint on the tibia and the over-the-top position on the femur.

images  Minimal notchplasty is performed to avoid iatrogenic injury to the perichondrial ring of the distal femoral physis, which is very close to the over-the-top position (see Fig 1).2

Tibial Tunnel Preparation

images  A tibial tunnel guide (set at 50 to 55 degrees) is used through the anteromedial portal.

images  The hamstrings harvest incision is used and a guidewire is drilled into the posterior aspect of the ACL tibial footprint.

images  The guidewire entry point on the tibia should be kept medial to avoid injury to the tibial tubercle apophysis.

images  The guidewire is reamed with the appropriate-diameter reamer based on the size of the graft.

images  Excess soft tissue around the tibial tunnel is excised to avoid the formation of a cyclops lesion, which may limit postoperative ROM.

images  The posterior rim of the tunnel is smoothed with a rasp to prevent graft abrasion over a sharp tunnel edge.

Femoral Tunnel Preparation

images  The transtibial over-the-top guide of the appropriate offset to ensure a 1-mm or 2-mm back wall is passed through the tibial tunnel and hooked around the back wall of the femur in the notch. Rotating the guide and slightly extending the knee help facilitate passage past the posterior cruciate ligament.

images  It is rotated to the 10:30 position on a right knee (1:30 on a left knee) and used to pass the femoral guide pin.

images  The femoral guide pin is overdrilled with the EndoButton reamer.

images  Both are removed and a depth gauge is used to measure the femoral tunnel length.

images  The guide pin is replaced and brought through the distal lateral thigh.

images  The femur is reamed to the appropriate depth (femoral tunnel length − EndoButton length + 6 to 7 mm to flip the EndoButton).

Graft Passage and Fixation

images  The no. 5 Ethibond sutures on the EndoButton are placed in the slot of the guidewire and pulled through the tibial tunnel, through the femoral tunnel, and out the lateral thigh.

images  One set of sutures is used to “lead” the EndoButton, while the other set of sutures is used to “follow.” The lead sutures are used to pull the graft through the tibial tunnel and into the femoral tunnel (TECH FIG 4A).

images  Once the graft is fully seated in the femoral tunnel, the “follow” sutures are pulled to flip the EndoButton (TECH FIG 4B). The flip can be palpated in the thigh, and tension is applied to the graft to ensure that there is no graft slippage.

images  The knee is then extended to ensure that there is no graft impingement and cycled about 10 times with tension applied to the graft.

images  The knee is flexed to 20 to 30 degrees, tension is applied to the graft, and a posterior force is placed on the tibia.

images  On the tibial side, the graft is fixed either with a soft tissue interference screw if there is adequate tunnel distance (at least 30 mm) below the physis to ensure metaphyseal placement of the screw or with a post and spiked washer (TECH FIG 4C,D).

images  Fluoroscopy can be used to ensure that the fixation is away from the physis.

images

TECH FIG 4 • Graft passage and fixation for transphyseal reconstruction with metaphyseal fixation. A. The “lead” sutures (blue) are used to advance the EndoButton and graft through the tibial tunnel and into the femoral tunnel. B. Once the EndoButton is through the femoral cortex completely, pulling (1) on the other set of “follow” sutures (red) “flips” (2) the EndoButton perpendicular to the cortex. Pulling on the graft (3) seats the EndoButton and ensures stable fixation of the graft. C. Tibial fixation is with an interference screw if enough graft and tunnel length is present inferior to the proximal tibial physis. D. Alternatively, a post and spiked washer may be used.

images

POSTOPERATIVE CARE

images Rehabilitation after ACL reconstruction in skeletally immature patients is essential to ensure a good outcome, allow return to sports, and avoid reinjury.

images Rehabilitation in prepubescent children can be challenging. A therapist who is used to working with children and can make therapy interesting and fun is very helpful.

images Compliance with therapy and restrictions should be carefully monitored.

images Weight bearing is limited to touch-down weight bearing for 6 weeks for the physeal-sparing technique and for 2 weeks for the transphyseal technique in adolescents with growth remaining.

images A protective brace is used for 6 weeks postoperatively.

images ROM is limited from 0 to 90 degrees for the first 2 weeks, followed by progressive full ROM.

images A continuous passive motion (CPM) machine from 0 to 90 degrees and cryotherapy are used for 2 weeks postoperatively.

images Progressive supervised rehabilitation consists of ROM exercises, patellar mobilization, electrical stimulation, pool therapy (if available), proprioception exercises, and closed-chain strengthening during the first 3 months postoperatively. A running program that progresses through straight-line jogging, plyometric exercises, and finally sport-specific exercises follows.

images Return to full activity, including cutting sports, is usually allowed at 6 months if the patient has achieved full ROM, has 90% strength compared to the uninjured leg, and can perform a single-leg hop to 90% of the uninjured leg.

images A functional knee brace is routinely used during cutting and pivoting activities for the first 2 years after return to sports.

OUTCOMES

images Performed properly, physeal-sparing combined intra-articular and extra-articular ACL reconstruction using iliotibial band in preadolescent skeletally immature patients appears to provide an excellent functional outcome, with a low revision rate and a minimal risk of growth disturbance.

images The largest study of outcomes after physeal-sparing reconstruction noted a 4.5% revision rate for graft failure at 4.7 and 8.3 years postoperatively, which is comparable to rates for reconstructive procedures in adults (2.3% to 5.3%).6,12

images No cases of significant angular deformity measured radiographically or leg-length discrepancy measured clinically were noted in this series.

COMPLICATIONS

images Growth disturbanc.

images Leg-length discrepancy

images Distal femoral valgus

images Tibial recurvatum with an arrest of the tibial tubercle apophysis

images Arthrofibrosis, particularly loss of extension

images Graft failure

images Recurrent instability despite an intact graft, requiring revision to more anatomic reconstruction at skeletal maturity

images Tunnel widening

images Infection

images Deep venous thrombosis

REFERENCES

1. Aichroth PM, Patel DV, Zorrilla P. The natural history and treatment of rupture of the anterior cruciate ligament in children and adolescents: a prospective review. J Bone Joint Surg Br 2002;84B:38–41.

2. Behr CT, Potter HG, Paletta GA Jr. The relationship of the femoral origin of the anterior cruciate ligament and the distal femoral physeal plate in the skeletally immature knee: an anatomic study. Am J Sports Med 2001;29:781–787.

3. Daniel DM, Stone ML, Dobson BE, et al. Fate of the ACL-injured patient: a prospective outcome study. Am J Sports Med 1994;22:632–644.

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