Femoral-Physeal-Sparing ACL Reconstruction With Lateral Extra-articular Tenodesis and Inside-Out Repair of Lateral Meniscus in a Skeletally Immature Patient

Abstract

Background:

Anterior cruciate ligament (ACL) reconstructions in skeletally immature patients have an increased risk of graft failure and a decreased rate of successful return to sports. Anterior cruciate ligament reconstructions (ACLRs) combined with lateral extra-articular tenodesis (LET) procedures are reported to limit anterolateral rotary instability of the knee, decreasing tension on the ACL graft. However, the open physes found in pediatric patients present unique challenges for ACLR. This video demonstrates a technique to avoid the femoral physis and necessary precautions for performing an ACLR with LET in a skeletally immature patient.

Indications:

The indications for combined ACLR and LET, as opposed to ACLR alone, mainly center on the risk factors for graft failure. These include the following: posterior tibial slope >12°, revision ACLR, high-grade pivot shift on physical examination, meniscal deficiency, generalized ligamentous hyperlaxity, and—especially pertinent to this procedure—skeletally immature patients.

Technique Description:

Standard plain radiographs and long-leg alignment films, along with a magnetic resonance imaging (MRI) study, are necessary to assess for malalignment, bone age, and concomitant meniscal and chondral pathology. This technique describes the senior author’s preferred technique for pediatric ACLR with LET. The senior author’s preferred order of operations includes performing the autologous hamstring graft harvest and LET before performing the diagnostic arthroscopy. This is followed by the intra-articular work including the ACLR. It is also the senior author’s preference to perform physeal-sparing femoral tunnels, using fluoroscopy for tunnel placement.

Results:

Getgood et al reported that an ACLR with an LET in young patients with a high risk of graft failure had a significant reduction in graft rupture compared to an ACLR alone. Furthermore, Noyes et al reported a significantly lower rate of graft failure and a higher rate of return to sports in those who received LET in addition to ACLR compared with those who received ACLR alone.

Discussion:

An ACLR combined with an LET has been reported to reduce graft failure rates and improve clinical outcomes in high-risk patients. An ACLR with LET may also be considered in skeletally immature patients with appropriate indications and extra precautions to avoid growth arrest or deformity.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This presentation is entitled femoral-physeal-sparing anterior cruciate ligament (ACL) reconstruction with lateral extra-articular tenodesis (LET) and inside-out repair of lateral meniscus (LM) in a skeletally immature patient.

The authors’ disclosures are listed on this slide.

ACL tears are a common injury, presenting with pain, instability, and swelling. ACL deficiency and the associated instability, specifically in a younger more active patient population, can lead to secondary meniscal and chondral injuries. Large meniscal tears also contribute to instability and pain and increase the risk of ACL graft failure if left unrepaired.

Lateral extra-articular tenodesis is used concomitantly with ACL reconstruction in patients at high risk for graft failure. This includes patients with previous ACL failure, increased posterior tibial slope, high-level pivot shift, and positive Lachman tests on examination, and so on.^2,7

Skeletally immature patients pose additional challenges such as joint hypermobility, size and length of autograft options, and open physes. These challenges increase the risk of iatrogenic injury and ACL reconstruction failure. ²

The patient demonstrated in this case is a 9-year-old boy active in sports who injured his left knee on the trampoline 2 months prior to his initial office visit, resulting in pain and instability. Seven weeks after the initial visit, he jumped off a piece of playground equipment and worsened his injury. He was previously treated with an over-the-counter brace, and has no prior history of knee injury or medical problems. He desired to return to playing sports.

Examination of the left knee revealed no obvious deformities, with skin intact and without erythema, rashes, or swelling. He was neurovascularly intact with tenderness to palpation about the lateral joint line and decreased range of motion from 0° heel height to 140° flexion compared with 4° heel height and 140° flexion on the right. He had grade 2 Lachman and pivot shift tests with some guarding, and he was stable to varus and valgus stress.

The exam was ultimately suggestive of ACL injury with concern for a lateral meniscal tear.

Imaging was ordered. The patient’s AP, lateral, and full-length standing plain films were unremarkable apart from open physes.

Magnetic resonance imaging revealed a conspicuously absent ACL with a large lateral meniscal posterior horn tear. The final diagnosis was a complete ACL tear and lateral meniscal posterior horn tear in a skeletally immature patient with open physes.

After consulting with the patient and his parents about the risks and benefits of operative versus nonoperative or delayed operative treatment, they elected to proceed with single-staged ACL reconstruction with hamstring autograft, concurrent lateral meniscus inside-out repair and LET. The senior author’s indications for LET include patients, adult or pediatric, who have increased risk of ACL graft failure. More specifically, these risk factors include but are not limited to increased posterior tibial slope >12°, increased hypermobility via the Beighton score and specifically increased recurvatum, revision ACL, high-grade pivot shift on examination, and young age. Given this patient’s young age, the known high failure rates in ACL reconstruction (ACLR) in this population combined with the patient having a high-grade pivot-shift on examination persuaded us to include the LET in the hopes of reducing his risk of failure.^2,5,7

An examination under anesthesia revealed a 3+ anterior Lachman and pivot shift examinations.

For this technique, the patient is positioned supine with a leg abduction stirrup and a standard leg holder.

For the quadruple hamstring graft, an incision is made over the pes anserinus and dissection commences down to the gracilis and semitendinosus tendons. After blunt release of tendinous vinculi, an open hamstring harvester used to isolate and release the tendons proximally. Sharp dissection is used to remove the distal tendon from the tibia.

The graft is prepared on the back table by doubling each tendon to form a quadruple bundle with a diameter of 7.5 mm and then whipstitching them over a 10-mm surgical button with passing sutures.

Attention is now turned to the LET. An incision is made 8 cm proximal to Gerdy tubercle along the IT band, being sure to expose the posterior 1/3 of the IT band. A 1 cm × 8 cm strip of IT band within the posterior 1/3 is marked out and incised, leaving it attached to Gerdy’s tubercle and ensuring enough posterior Kaplan fibers remain to close the IT band later. The end of the graft is whipstitched. The fibular collateral ligament (FCL) is identified, and a passing tunnel created under it with blunt dissection. The graft is passed under the FCL, and the insertion site proximal to the physis is identified using fluoroscopy and prepared.

We proceed with arthroscopy through standard medial and lateral incisions, and the joint is insufflated with normal saline. Diagnostic arthroscopy reveals an intact patellofemoral compartment and medial meniscus with good cartilage throughout. The LM is noted to have a large peripheral tear starting near the posterior root and extending vertically to a point anterior to the popliteus tendon. The posterior cruciate ligament (PCL) is intact, but the ACL is almost completely absent with only a few fibers remaining on the femoral and tibial attachment sites.

After debridement with an arthroscopic shaver, the coagulator is used to mark the center of the femoral ACL footprint, posterior to the lateral intercondylar ridge and just proximal to the bifurcate ridge. A retrograde pinpoint guide is placed and the femoral tunnel is drilled with a 2.4-mm guide pin. Fluoroscopy is used to confirm tunnel placement and ensure the reamer will not overlap with the physis.

The tunnel is then reamed using a 7-mm retro-reamer in this patient, leaving 4 mm of bone on the lateral cortex for the surgical button. The arthroscope is used to visualize the tunnel and ensure the physis has not been violated.

With the femoral ACL tunnel prepared, attention is turned to the lateral meniscus repair. An inside-out technique is used in this patient, as the lateral aspect of the knee is conveniently open for the LET and femoral tunnel. Starting inferior to the IT graft site, dissection is carried down to the posterolateral capsule, and a retractor is placed to protect the gastrocnemius and biceps femoris musculotendinous structures.

An arthroscopic self-passing device is used to carefully pass double-ended suture needles through the lateral meniscus and lateral capsule on either side of the tear site. The needles are caught outside and removed, and the sutures are eventually tied down over the capsule. Seven vertical mattress sutures were required in this patient. The final construct is probed and found to be secure.

It was noted that the anterior tibial translation was diminished after this repair, indicating the additional stability the posterior meniscus offers for stability of the tibiofemoral joint.

Returning attention to the ACL reconstruction, the tibial ACL footprint is identified and the center marked with the coagulator near the anterior horn of the lateral meniscus. The tibial tunnel guide is set to 70° in this patient to ensure it is as vertical as possible as it crosses the tibial physis. Care is taken to ensure the tunnel is placed anterior to the MCL on the tibia. A guidepin is drilled and then over-reamed with a 7-mm acorn reamer. The tunnel is assessed with the arthroscope from both sides to ensure the grafts can be easily passed. The passing stitch for the ACL graft is then passed through the tibial tunnel and subsequently used to pass the graft. The surgical button is pulled through the femoral cortex and flipped, after which tension is applied to secure it against the periosteum. The graft is checked arthroscopically to ensure there is no impingement on the roof of the intercondylar notch.

The graft is fixed to the tibia with the knee in full extension using two small bone staples. This eliminated the patient’s Lachman test.

The anchor guide for the suture anchor to fix the LET is assessed fluoroscopically to ensure it is placed superior to the physis and angled such that it does not enter the physis. The anchor is then drilled and deployed, after which the graft is tied down with the knee in 30° flexion and the foot in neutral rotation. The ACL graft is visualized one last time to verify there is no graft impingement and the ACL graft is taut, and the incisions are closed with suture, including the IT band.

Given the complexity of this case, there are complications which can be encountered. Physeal disruption during femoral tunnel drilling can occur and should be aimed to be avoided. Using fluoroscopy and retrograde drilling help to ensure appropriate tunnel entrance and exit points which allow optimal anatomic tunnel position which avoids the physis. Neurovascular injury during inside-out meniscal repair has been reported in the literature and should be avoided. Using the same incision from the LET graft harvest, the interval deep to the lateral head of the gastrocnemius and anterior to the posterolateral capsule and above the long biceps tendon can be developed. Then a protective retractor can be placed in this interval to ensure adequate visualization. Finally, communication between suture passer and catcher is paramount to ensure safe needle trajectory. Inadequate hamstring size is another complication that can be encountered and can be avoided by appropriate preoperative planning with an MRI and assessment of hamstring size.

Fluoroscopy is used to find an appropriate start point for entry of the retrograde reamer for creation of the ACL femoral tunnel. As the preferred technique of the senior author is physeal sparing, the starting point is therefore distal to the physis. The IT band tenodesis site may be easily ascertained proximal to the physis using fluoroscopy, and further the anchor may be slightly angled proximally to ensure it will not deviate distally through the physis. Convergence of the tunnel and anchor therefore is not a concern in this technique due the fact that they are located on opposite sides of the physis and their location and trajectory are confirmed by fluoroscopy. ²

Postoperative rehabilitation for these patients is immediate weightbearing as tolerated with ambulatory aid only until limping ceases. There are no limits on range of motion, and physical therapy should be aggressive with regaining full knee extension. The goal for return to sport is 10 to 14 months. Because open-growth plates pose a risk of growth arrest or deformity, follow-up plain radiographs will be assessed at 6 months postoperatively and then annually until the physes are closed. Due to this patient’s age, only mechanical DVT prophylaxis was used.

The decision to perform ACL reconstruction in children has a controversial past; to that end, an international panel of experts has put out consensus guidelines for diagnosis, management and treatment of these injuries. Relevant to our patient, the accepted indications for surgical treatment include associated injuries requiring surgery such as our patient’s concomitant large meniscal tear, persistent symptoms despite nonoperative management—especially instability, and unacceptable limitations on the child’s participation in daily or desired activities. They also delineate the advantages and disadvantages of various tunnel-placement techniques, with the admonition that compared to transphyseal techniques, physeal-sparing femoral tunnel placement includes ideal ACL placement and avoids physeal damage but is technically challenging to place. ⁴

Regarding physeal-sparing femoral tunnel placement for ACLR in skeletally immature patients, Shea et al performed a laboratory-based anatomy study with the aid of CT imaging to help surgeons determine the precise location of the ACL footprint on lateral intraoperative fluoroscopy of the femur. The precise location was found to be 14%, the distance from posterior to anterior and 38% proximal to distal, which is epiphyseal, posterior and inferior to the FCL footprint, and posterior to the popliteus tendon attachment. ⁶

Lateral extra-articular tenodesis has been shown in prior studies to reduce the rate of ACL graft rupture and persistent rotatory instability in young patients, as demonstrated in this randomized controlled trial by Getgood et al with 2-year follow-up which found the rate of both clinical failure and graft rupture to be decreased by over 50% when LET was added to the ACL reconstruction. ³

A systemic review of ACLR with LET in skeletally immature patients by Carrozzo et al reviewed 5 studies with 381 patients that showed a graft failure rate reduction similar to that seen with ACLR and LET in adults. ¹

Final postoperative day 1 imaging shows the knee in good alignment on AP and lateral views with hardware in good position and no overlap with the physes.