Technique: Anterior Cruciate Ligament Reconstruction: All-Epiphyseal Sockets

Elizabeth B. Gausden

Daniel W. Green

Frank A. Cordasco

INTRODUCTION

Although previously considered uncommon in skeletally immature patients, given the strength of the cruciate ligaments over physeal integrity, current literature suggests an increase in incidence of anterior cruciate ligament (ACL) injury in pediatric patients.¹,² Dodwell et al.³ reported that the rate of ACL reconstruction per 100,000 population aged 3 to 20 years in New York State has increased from 17.6 in 1990 to 50.9 in 2009. In a Scandinavian database study, the incidence of ACL reconstruction was 76 in 100,000 girls and 47 per 100,000 boys between the ages of 10 and 19 years.⁴,⁵

Nonoperative management of ACL injuries in the skeletally immature population is associated with poor outcomes, including cartilage and meniscal damage as well as instability.⁶ Children with ACL tears treated nonoperatively have a 50% sport dropout rate because of recurrent instability.⁶ As standard adult ACL reconstruction involves drill holes that traverse physes, there is a risk of physeal damage and potentially leg length discrepancy over time. Orthopedic surgeons and researchers have not been able to fully quantify the risk of angular deformities and growth disturbances resulting from standard ACL reconstruction with transphyseal tunnels. Part of the difficulty in assessing risk is that the injury creating an ACL tear may independently cause a growth disturbance.⁷

One meta-analysis of 55 studies found a rate of growth disturbance following ACL reconstruction in the skeletally immature patient of 2%.⁸ Similarly, Kocher et al.⁹ found that 11% of knee surgeons reported a growth disturbance in skeletally immature patients following ACL reconstruction. A study that assessed physeal injury with magnetic resonance imaging (MRI) found that the graft diameter was the most critical variable affecting the volume of physeal injury, whereas increased drill angle was associated with less physeal injury.¹⁰

In the past, delaying ACL reconstruction until patients reached skeletal maturity was a more common approach. However, studies indicate that delaying ACL reconstruction can predispose the young athlete to chondral injury and meniscal tears as a result of recurrent knee instability. Furthermore, fewer patients and parents are willing to accept bracing and activity restriction required for nonoperative management or delayed surgical management.

Both the increasing incidence of ACL injuries in juvenile populations as well as consistently poor results with nonoperative treatment have stimulated interest in developing ACL reconstruction techniques suitable for the pediatric population.⁹,¹¹,¹² Therefore, we recommend pediatric ACL reconstruction for the majority of our young active pediatric and adolescent athletes with a complete tear. Although various techniques for pediatric ACL reconstruction have been published in the literature, there is currently a lack of high-level research to suggest that one technique is superior to the others at this time.

TECHNIQUES DESCRIBED IN LITERATURE

As described in the previous and subsequent chapters, there are a variety of surgical techniques used to reconstruct the ACL in a skeletally immature patient. These techniques can be classified into three broad categories: extraphyseal reconstruction, transphyseal reconstruction, and the all-epiphyseal reconstruction. The most popular “over-the-top” reconstruction uses a pedicled iliotibial band and is known as the modified McIntosh reconstruction, which is an extraphyseal reconstruction using a combined extra- and intra-articular approach.¹³

The disadvantage of extraphyseal reconstructions is that they do not accurately recreate the anatomy of the ACL and may tend to overconstrain the knee, but the clinical consequence of this has yet to be fully elucidated.³¹ There are numerous transphyseal or partial transphyseal techniques that involve transphyseal stabilization of an ACL graft on either the femoral or tibial side, or both.¹⁴ Finally, a number of all-epiphyseal techniques, or techniques that involve graft fixation within the epiphysis without crossing the physes, have been popularized recently.¹⁵,¹⁶,¹⁷,¹⁸,¹⁹

The remainder of this chapter focuses on the all-epiphyseal technique developed by the co-editors of this textbook (F.A.C. & D.W.G).¹⁶

One of the unique aspects of this technique is that, in addition to socket positioning that is all-epiphyseal, the sockets are created from the inside out, leaving a cortical bone bridge on the lateral femoral condyle and medial proximal tibia. These sockets may allow for improved graft to bone healing.^19a Furthermore, our technique uses suture tensioning buttons across the bone rather than tenodesis screws within the softer noncortical epiphyseal bone to achieve graft fixation.

OUR PREOPERATIVE PLANNING

Our preferred all-inside, all-epiphyseal ACL reconstruction technique is intended for skeletally immature patients with more than 3 years of growth remaining. The specific algorithm we use for addressing ACL injuries in pediatric patients is discussed in a later chapter.²⁰

In preparation for ACL reconstruction in a skeletally immature patient, we routinely obtain a posteroanterior (PA) radiograph of the patient’s left hand to assess skeletal age as well as standing radiographs to evaluate leg length and overall alignment. An MRI of the affected knee including physeal-specific sequences (frequency-selective fat suppressed 3D spoiled gradient recalled echo [SPGFR]) is a routine component of the workup. After the acute injury phase, patients are enrolled in a strengthening program prior to surgery, depending on their age.

Once in the operating room (OR), a thorough exam under anesthesia is performed. The landmarks are identified, including the tibial tubercle, the distal femoral physis laterally along with the popliteus tendon insertion, the joint line, the inferior pole of the patella, and the anteromedial and anterolateral arthroscopic portals (Fig. 8.1).

Figure 8.1. Prior to incision, the landmarks are identified including the borders of the patella, tibial tubercle, the incision for hamstring harvest, the popliteus tendon insertion, and the femoral condyles.

Step 1: Graft Harvest

Hamstring autograft is the graft choice in this skeletally immature population. A 2-cm vertical incision over the distal insertion of the hamstring tendon is the preferred approach. The vertical incision allows evaluation of the tibial physis and will be used later for placement of the tibial guide (see Step 5).

Layer one of the medial structures of the knee, the sartorius fascia, is incised.²¹ The gracilis and semitendinosus tendons, which lie between the first and second layers of the knee, are identified. In general, both tendons are harvested unless the semitendinosus is large enough to provide a diameter of 9 mm or more. The semitendinosus and gracilis are left attached distally to facilitate the graftlink preparation. A native graft length of 27 cm will provide enough tissue to allow for an appropriate length for the final graftlink autograft (between 55 and 65 mm for the all-epiphyseal construct). If the combined tendons do not allow for a final diameter of at least 8.5 mm, we consider adding an allograft semitendinosus to the construct. This is discussed as a routine part of the consent preoperatively with the patient and family. Although it is clear from the literature that allograft alone is not an appropriate choice in this population of young athletes,²²,²³ we have not found that adding allograft to autograft tissue when the diameter is less than 8.5 mm has been a clinical problem and we are not comfortable using a graft less than 8.5 mm in diameter given the evidence in the literature.²⁴,²⁵,²⁶,²⁷ An alternative is to harvest the contralateral semitendinosus in this setting. Given the incidence of contralateral injury in this population of young athletes, we prefer to supplement with allograft than to harvest contralateral autograft.

Step 2: Graft Preparation

A graft preparation table is used to construct the tendon graft and to secure the surgical fixation on the femoral end (Fig. 8.2). The tendons are looped together on this table to increase the graft’s diameter. The result is a shorter and thicker graft, which is biomechanically stiffer (Fig. 8.3). A TightRope RT suture (Arthrex, Naples, FL) is used on the femoral end of the graft, and a free TightRope Attachable Button System (ABS) is used for fixation on the tibial end.

Our preference is to secure the graft on both the tibial and femoral side using suspensory fixation in the form of a reverse tensioning (RT) button (TightRope RT device) and a free tensioning button (ABS device) on the tibial side using the GraftLink technique. We modified the original technique of using TightRope RT buttons on both sides, as we found that passing the tibial button through the anteromedial portal and through the tibial socket was unnecessary. The length of the graft is generally 55 to 65 mm (Fig. 8.4). If the length of the graft is too long, it will “bottom out” in one of the sockets; but if it is too short, it may compromise biologic fixation within the socket. The diameter of the graft is assessed through the same sizing block.

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