ACL Repair of Femoral Osseous Avulsion in a 13-Year-Old Using Suture Pullout Technique

Abstract

Background:

The incidence of pediatric anterior cruciate ligament (ACL) injuries has been increasing over the past 20 years, with the majority comprised of mid substance tears or tibial eminence avulsion fractures. Pediatric femoral sided osseous avulsion is rarely reported in orthopedic literature and specific surgical indications and contraindications, as well as recommended surgical techniques and postoperative rehabilitation protocols, are underdefined.

Indications:

The surgical indications for femoral-sided repair of ACL osseous avulsion includes a displaced osseous fragment and ligamentous laxity on physical examination. There was no concomitant midsubstance tear necessitating reconstruction.

Technique Description:

Two sutures piercing the proximal ligamentous bony junction of the ACL were fed through 2.4-mm transphyseal tunnels and secured with cortical button and backup fixation with a 3.9-mm swivel lock anchor in the proximal lateral femoral metaphysis. The patient was immobilized in a hinged-knee brace locked in extension during ambulation and limited to 90 degrees of flexion while nonweightbearing for the first 6 weeks after surgery. Standard ACL protocol was followed thereafter.

Results:

Successful fixation and restoration of ligamentous tension and impingement-free range of motion were achieved without complication. There was stable Lachman, negative pivot shift, 125 degrees of knee flexion, and evidence of early healing at 3 months follow-up.

Discussion/Conclusion:

This report demonstrates successful reduction and fixation of proximal bony avulsion of the ACL. Although this patient exhibits stable physical examination and undisturbed growth at early follow-up, more research is required to establish treatment and rehabilitation guidelines for this rare injury.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

In this video, we present the “ACL Repair of Femoral Osseous Avulsion in a 13-Year-Old Using Suture Pullout Technique.” My name is Andrew Moore, with the Medical University of South Carolina, working alongside Dr. Kathy McGurk and Dr. Harris Slone, associate professor of orthopaedic surgery. Also contributing is Jess Rames at Duke University.

Of note, Dr. Harris Slone is an editorial board member for the Video Journal of Sports Medicine. The authors report no disclosures otherwise.

There are few previous reports of pediatric femoral anterior cruciate ligament (ACL) osseous avulsions with high variability in surgical technique. In this report, we demonstrate our surgical technique for repair of femoral-sided osseous avulsion with 2.4 mm transphyseal tunnels secured with cortical button. Successful fixation and restoration of ligamentous tension and impingement-free range of motion were achieved. Early follow-up demonstrates stable ligamentous examination to date. Although growth disturbance is not reported in the literature, this risk was mitigated by using small 2.4 mm femoral tunnels. More research is required to establish treatment and rehabilitation guidelines for this rare injury.

A previously healthy 13-year-old boy was evaluated in the pediatric emergency department after sustaining a left knee injury while wrestling, in which he twisted his left leg after being thrown onto the mat by his opponent. He endorsed immediate knee swelling, as well as sharp anterosuperior pain, rated an 8/10 in intensity, and difficulty with weight bearing. Radiographs obtained in the emergency department showed a large effusion on sunrise, anteroposterior, and lateral views, along with a subtle, linear cortical irregularity on the lateral femoral condyle on anteroposterior view. Therefore, given concern for ligamentous injury, an magnetic resonance imaging (MRI) was immediately obtained. The patient was placed into a knee immobilizer and sent for outpatient orthopedic follow-up.

Upon presentation to our office later that week, the patient’s pain had improved significantly. There was a moderate effusion and range of motion was limited from neutral to 60 degrees of knee flexion. There was a grade 2B Lachman, but pivot shift was limited secondary to guarding. The knee was stable to coronal plane stress at 0 and 30 degrees of flexion. Previously acquired MRI revealed osseous ACL avulsion off the femoral side.

The incidence of pediatric ACL injuries has been increasing significantly over the past 20 years, with the majority comprised of midsubstance tears or tibial eminence avulsion fractures. Femoral-sided osseous avulsion injuries are relatively uncommon, with very few case reports available in orthopedic literature, especially in adolescent patients. Given the rarity of these injuries, specific surgical indications and contraindications, as well as recommended surgical techniques and postoperative rehabilitation protocols, are underdefined.

Relative surgical indications for femoral-sided repair of an ACL osseous avulsion include a displaced osseous fragment, ligamentous laxity on examination, or associated chondral and/or meniscal injuries requiring surgery. Osseous avulsion fractures with concomitant midsubstance tears would necessitate reconstruction rather than repair. Nondisplaced avulsion fractures or patients with stable ligamentous examination may be treated nonoperatively. We elected to repair the osseous avulsion in an attempt to restore stability to the native knee without formal reconstruction and preserve natural biomechanics and proprioception. In this report, we describe our surgical technique for repair of a displaced femoral-sided osseous ACL avulsion in addition to a postoperative protocol.

The previously mentioned noncontrast MRI revealed displaced osseous avulsion of the femoral ACL attachment. Other findings included bone bruise consistent with pivot shift mechanism, no significant meniscal or chondral injury, low-grade medial collateral ligament sprain, lipohemarthrosis, and open physes. Additionally, there was subtle increased signal within the substance of the ACL, but the majority of ACL fibers were intact. Operative versus nonoperative interventions were discussed, and the patient’s family elected to proceed with surgical intervention. They consented for fixation of osseous fragment versus physeal sparing reconstruction with quadriceps tendon autograft in the event that midsubstance tearing was encountered intraoperatively.

The patient was placed supine on an operating room table, and general and regional (adductor canal block) anesthesia were administered. Examination under anesthesia revealed a grade 2B Lachman and grade 2 pivot shift. A nonsterile tourniquet was applied to the operative thigh.

The operative extremity was prepped and draped in a sterile manner. A surgical pen was used to outline the patellar borders and mark the proposed locations for the arthroscopy portals. Local anesthetic with epinephrine was then injected into the subcutaneous tissue surrounding proposed portal sites in order to reduce intraoperative blood loss and postoperative pain. At this point, the surgery was started.

An Esmarch bandage was used to exsanguinate the extremity, and the tourniquet was inflated. The anterolateral portal was made, and diagnostic arthroscopy performed, beginning with the suprapatellar pouch and patellofemoral joint. A significant amount of hemarthrosis was immediately encountered and successfully evacuated. An arthroscopic probe was introduced, and all portions of the medial meniscus were probed and noted to be stable. The lateral compartment and meniscus were examined in a similar fashion, and no meniscal tears nor chondral injuries discovered.

At this point, the ACL was probed, and was noted to be lax. The tibial ACL attachment was normal as well as the mid substance of the ligament. Consistent with MRI findings, there was proximal bony and periosteal avulsion from the medial aspect of the femoral intercondylar notch. At 90 degrees of flexion, the fragment was relatively reduced; however, the femoral attachment displaced as the knee was brought into extension. The avulsion was temporarily reduced with the probe to ensure the ACL maintained a correct length, and if repaired, would restore proper tension. The arthroscope was placed through the anteromedial portal to further evaluate the femoral-sided injury. Of note, the ligamentous fibers were intact, and based on these findings it was determined that the osseous avulsion would be amenable to repair.

Next, a cinch stitch was placed using a Suturetape Fiberlink (Arthrex, Naples, Florida) suture at the proximal ligamentous bony junction by means of a labral passer through the anteromedial portal. This stitch was used to retract the proximal ACL for the purpose of exposing the femoral donor site for debridement and manipulating the bony fragment for ease of suture placement. The cinch stitch was brought out through a small accessory anteromedial percutaneous portal that was established under arthroscopic visualization just above the medial meniscus.

A Passport cannula (Arthrex) was placed in the anteromedial portal. With the knee remaining at 90 degrees flexion, the first stitch was passed through the posterior aspect of the ACL at the bone-ligament junction. A second stitch was placed toward the anterior aspect of the femoral ACL at the bone-ligament junction.

A Freer elevator was used through the accessory medial portal to gently retract the osseous fragment. The bony footprint was prepared by debriding interposed hematoma and periosteum with a shaver.

A flip cutter ACL guide with 2.4-mm bullet was then inserted through the anterolateral portal while visualizing the knee through the anteromedial portal. A small incision was made over the lateral aspect of the knee. A hemostat was used to spread soft tissues down to bone and the bullet was placed down to the lateral metaphysis. With the knee at 90 degrees of flexion, a 2.4-mm beath pin was then drilled in an outside in fashion, with the pin exiting posteriorly in the donor site. A parallel guide was used to place a second pin anterior to the first. We elected to use 2.4-mm pins to reduce the risk of physeal injury. The anatomical orientation of the tunnels corresponded to the sutures previously placed on the ACL such that all of the suture tension translated into appositional force between the osseous fragment and femur, restoring normal anatomy.

The 2.4-mm guide pins were replaced with cannulated 2.4-mm passing needles. Nitinol passing wires were consecutively fed through the cannulated guide pins and used as a passing stiches to shuttle the repair stitches through their corresponding femoral tunnels. The ACL sutures were sequentially passed through the femur and out of the lateral metaphysis. Reduction of the fragment was achieved with tension on the repair sutures.

The ACL was probed with the ACL stump temporarily held in apposition, and there was appropriate ligament length and tension. Under direct visualization, the knee was brought through range of motion with tension on the sutures and there was no impingement of the repaired ACL at this point.

Sutures were then passed through the existing incision in the iliotibial band to avoid a soft tissue bridge. Femoral sided fixation strategies are numerous and based on surgeon preference. A cortical button was placed down to bone, and sutures were tied over top in standard fashion. After the button was secured, the sutures were fed underneath iliotibial tract tissue toward the more proximal aspect of the lateral femoral metaphysis where a 3.9-mm swivel lock anchor was utilized as backup fixation.

Following fixation, a Lachman maneuver was performed, and the knee was well tensioned. The arthroscope was reinserted, and the ACL was anatomically positioned. Probe of the repaired ACL revealed appropriate tension. Range of motion was assessed a final time and there was no restriction of motion or impingement. Arthroscopic fluid was drained from the knee. The iliotibial band, overlying skin, and arthroscopy portals were closed, and sterile dressings applied. The tourniquet was deflated, and the knee was immobilized in full extension.

Potential complications include failure of fixation, growth disturbance, nonunion, stiffness, residual laxity, and retear. Reoperation after femoral avulsion fracture fixation has not been reported in a pediatric patient, however, failure of primary soft-tissue ACL femoral avulsion repairs in the young population has a high failure rate. Additionally, reoperation rate for tibial eminence fracture repairs, an analogous procedure, has been reported as high as 20%.

Growth disturbance is associated with fixation spanning across the lateral distal femoral physis and is likely a risk that warrants close follow-up. We attempted to minimize this risk by drilling two 2.4-mm holes, limiting the cross-sectional area of damage to the physis. Upon our review of the limited available literature, there have been no documented growth disturbances in previous reports of transphyseal femoral osseous avulsion repair in pediatric patients. However, our technique could easily be modified to an all-epiphyseal technique if desired.

Immediately postoperative and for the first 6 weeks following surgery, the patient was immobilized in a hinged-knee brace locked in extension during ambulation and limited to 90 degrees of flexion while nonweightbearing. Physical therapy focusing on quad sets and straight leg raises was started immediately postoperative as well. Standard ACL protocol was followed after 6 weeks.

Postoperative x-rays were obtained at 2 weeks, 6 weeks, and 3 months. Long leg x-rays will be obtained at 6 months postoperatively to assess for growth disturbance.

As with ACL reconstruction, there is significant individual variability regarding return of normal neuromuscular function, and our patient’s return to sport will be dictated by his progression through the stages of therapy. Functional testing and comanagement with a qualified physical therapist will help determine return to sport timing.

There were no apparent postoperative complications. Anteroposterior and lateral x-rays at 3 months postoperative showed no evidence of early growth disturbance, and anatomic reduction of osseous fragment with evidence of early interval healing. On physical examination, there was stable Lachman, negative pivot shift, over 125 degrees of knee flexion, and the knee was stable to varus and valgus stress.

There is a paucity of data regarding surgical treatment and outcomes of pediatric femoral osseous ACL avulsion, however, various surgical techniques have been reported without documented growth deformities. This report will expand the existing literature and knowledge base for the benefit of future patients with this rare injury.