Lateral Extra-Articular Tenodesis in the Young Athlete: Can We Reduce the Risk of Re-Injury?

Graft rupture following ACL reconstruction is 1 of the major concerns for both patients and providers. Young athletes are the group with the highest risk for reinjury due to the demand they place on the reconstructed ACL. As a result, much consideration has been directed toward reducing the risk of graft rupture. Lateral extraarticular tenodesis (LET) is an adjunct procedure performed along with ACL reconstruction in an attempt to reduce the risk of reinjury. During this procedure, an additional soft tissue structure is constructed on the lateral portion of the knee to reduce residual rotatory instability, which is considered a risk factor for ACL graft rupture. This procedure has been shown in both pediatric and adult cohorts to significantly reduce reinjury rates and has been incorporated into the practice of many pediatric orthopedic surgeons. However, variation exists in the indications for LET, and concerns regarding the addition of a nonanatomical structure to the knee remain, making some surgeons hesitant to adopt this procedure. Promising findings suggest that LET is a strong option to reduce the risk of ACL graft rupture with low risk for additional complications, but more research is necessary regarding this procedure, particularly in pediatric cohorts.

Introduction

Among patients who undergo anterior cruciate ligament (ACL) reconstruction (ACLR), pediatric and adolescent patients have a particularly high risk of graft rupture. One meta-analysis reported rupture rates between 0% and 83.3%, with an overall estimate of 8.7%. A 2020 case series of nearly 1000 pediatric patients performed by DeFrancesco et al utilized survival analysis to estimate graft rupture rates and demonstrated a rate of 19.7%. Graft rupture is a destructive and damaging complication that is estimated to require surgical treatment in over 90% of cases. Additionally, revision procedures have demonstrated inferior patient-reported outcomes, higher complication rates, higher risk of contralateral ACL injury, and decreased return-to-sport rates.

Pediatric patients often have goals of returning high-impact, high-risk activities. The level of demand placed on ACL grafts by young athletes is postulated to contribute to the high rate of graft rupture. In addition, restoring rotatory stability has proved to be a particularly challenging component of ACLR and postoperative rehabilitation. Many postoperative patients continue to exhibit rotatory laxity, exhibited by a positive pivot shift. ^, The increased rate of graft rupture among pediatric patients, in tandem with the psychological, physical, and economic burden of ACL graft rupture, create particular interest in preventing ACL reinjury.

Lateral extra-articular tenodesis (LET) is a surgical technique that is used to augment anatomic ACLR in both primary and revision procedures. This procedure, first introduced by Lemaire in 1967, was originally developed as a primary treatment for ACL tears before intraarticular ACL reconstruction was developed. As an adjunct to intraarticular ACLR, LET is performed with the goal of reducing rotatory instability, thereby decreasing reinjury risk. The “pivot shift,” or subluxation of the tibia with internal rotation and valgus stresses, is an exam finding associated with rotatory laxity resulting from damage to the native ACL or ACL graft. Residual pivot shift following ACL reconstruction has been shown to correlate with decreased functional outcomes, a propensity to develop osteoarthritis, and higher graft rupture rates.

LET procedures have become a topic of much interest due to their potential to decrease ACL reinjury. The 2023 clinical practice guidelines published by the Journal of the American Academy of Orthopaedic Surgeons were the first to address LET procedures. Although the journal recommended surgeons consider performing an LET in select patients undergoing ACL reconstruction with hamstring autograft, the recommendation level was listed as “moderate” due to a paucity of long-term outcome research. Research in the pediatric population, especially skeletally immature patients is particularly limited. The presence of open growth plates further complicates the decision-making process for performing an LET as some techniques carry the risk of physeal injury and its attendant complications. As a result, debate persists regarding if, when, and how lateral extra-articular tenodesis procedures should be performed on the skeletally immature patient. This article aims to answer those questions by synthesizing the current literature on LET procedures for the skeletally immature patient by describing reported indications for LET, surgical techniques, biomechanical evidence, and clinical outcomes.

Anatomy of the Anterolateral Ligament

Significant overlap exists in the literature regarding reconstruction of the anterolateral ligament (ALL) and lateral extra-articular tenodesis (LET). While often used interchangeably and performed for many of the same reasons, it is important to note that these 2 procedures are distinct. The ALL is an anatomical structure that has been identified through cadaveric dissection. ^, LET is the addition of a nonanatomical structure for use as a lateral, external stabilizer. Therefore, while much of this article outlines the purpose of an LET, it is important to acknowledge the presence and function of the ALL. This section will outline the anatomy and development of the ALL in pediatric patients as it provides insight to the rationale and technique of constructing a lateral rotatory stabilizer, either anatomically through an ALLR, or nonanatomically through an LET.

Two cadaveric studies performed by Shea et al. examined both the presence and anatomy of the anterolateral ligament in skeletally immature knees. The first study involved dissection of 8 specimens, all younger than 5 years old. Only 1 of the 8 specimens demonstrated presence of an ALL. The second study built upon the findings of the first and included 14 knees ranging from age 7 to 11. In this study, the presence, appearance, and anatomy of the ALL varied with patient age. Among the 7 younger specimens, only 2 had an identifiable ALL, which was described in both cases as a thin sheet-like structure. In all 7 of the older specimens the ALL was visualized and described as a white pearly band. Taken together, the presence of the anterolateral ligament in older populations and its absence in younger populations suggests that the presence of the ALL is related to maturity and develops during the prepubertal period. ^,

Magnetic resonance imaging (MRI) has been used to assess the presence of the all in children of various ages. Among a sample of 363 knees (200 males, 163 females) of patients under the age of 18 years, Helito et al. found that the ALL was visualized in 69.4%. While the study team reported 100% visualization of the ALL in patients aged 17-18 years, the ALL was not visulaized in female patients under 7 years nor males under 6 years, supporting a relationship between ALL development and maturity.

The origin of the ALL and its anatomic relationship to the lateral collateral ligament (LCL) were shown to vary by Shea et al. The tibial attachment was found to be consistent during these dissections, while femoral origin varied. The median tibial insertion was 9 mm proximal to the tibial physis, at which point the ALL had a median width of 4 mm. The femoral origin demonstrated more variability. The median femoral origin was 10 mm distal to the femoral physis and 3 mm in width. In relation to the LCL, 3 ALL origins were located distal and anterior to LCL origin, 1 was proximal and anterior, 2 were proximal and posterior, 1 was purely anterior, and 2 shared the same origin as the LCL.

Indications for LET

Fig. 1 Indications for LET vary among surgeons. However, factors that are associated with increased risk of ACL graft failure are commonly considered indications for performing an LET. Patients under 25 years old, females, patients who participate in pivoting sports or activities, and those with generalized ligamentous laxity, operationalized as a Beighton score greater than 6 or more than 10 degrees of knee hyperextension, are often considered candidates for LET. ^, Other common indications for LET include high-grade pivot shift, defined as Grade 2 or higher, revision ACLR, increased posterior tibial slope, meniscus root injuries, and suspected ramp lesions. ^, ^, Presence of a Segond fracture —an avulsion fracture of the tibia at the site of ALL attachment may also be a relative indication for an LET.

A study surveying 87 surgeons belonging to the Pediatric Research in Sports Medicine society found that the most commonly reported indications for LET procedures during primary ACLR were high-grade pivot shift, knee hyperextension greater than 10 degrees, generalized laxity, and type of sports participation. However, only 22 of the 87 surgeons reported that they would perform an LET during primary ACLR. Reasons against performing LET or ALLR in the primary setting included the most common response that “there was not significant evidence to warrant” performing the procedure, as well as concerns of over constraining the knee. Some surgeons reported thinking that the risks do not outweigh the benefits. Additionally, those who oppose performing LETs often argue that the ALL is not a distinct ligament, but simply a thickening of the anterolateral joint capsule. Investigations utilizing magnetic resonance imaging and ultrasonography, as well as comparative analysis of the variable findings within cadaveric studies provide support for this argument. Those who hold this belief argue that construction of a ligament that is not universally present may affect normal biomechanics of the knee.

Biomechanical analysis

Many biomechanical studies have investigated the role of the ALL in maintaining rotatory stability in the native and ACL-deficient knee, as well as the benefits provided by an adjunctive LET in controlling rotation. However, due to the limited number of pediatric cadaver specimens available, almost all research has been performed on adult specimens.

The role of the native ALL in limiting anterior translation and restoring rotational stability in the setting of ACL deficiency was evaluated by Trentacosta et al. In a sample of 8 knees of average age 62.6 years, anterior drawer, varus, valgus, internal rotation, and external rotation forces were applied and translation and rotation were measured in knees with intact ACL and ALL, transected ACL and intact ALL, and transected ACL and ALL. The study found that ACL- and ALL-deficient knees exhibited increased anterior tibial translation in comparison to ACL deficient knees with intact ALL ( P < 0.05). Further, the study found that in ALL-intact knees, ACL deficiency had no effect on rotational stability but noted that rotational movement increased significantly in ACL- and ALL-deficient knees, indicating that the ALL plays a role in native knee stability. These findings are consistent with the results of other studies that have evaluated knee stability following simulated ACL and ALL injury. ^,

Wytrykowski et al. studied the biomechanical properties of the different grafts used in ALLR/LET procedures, as well as the biomechanical effects of graft tension and knee positioning at fixation. Their study, consisting of 13 cadaver knees determined that both gracilis and iliotibial band (ITB) grafts have a higher maximum tensile load to failure than the native ALL when constructed in the configuration used for LET, however this finding was only significant for the gracilis graft. The ITB graft and ALL were found to have similar biomechanical properties in terms of maximum load to failure, stiffness and elongation.

The gracilis tendon graft was reported to be 6 times stiffer than the native ALL, and the authors raise concerns that excessive graft tension could increase pressure on the lateral compartment, limit range of motion and potentially lead to arthritis. Due in part to these concerns, debate persists regarding the optimal graft choice for LET. The study also found that graft fixation with the tibia in an over-reduced, externally rotated position successfully reduced rotational laxity, but also overly constrained anterior translation of the knee. However, fixation at 70 degrees of flexion and at neutral rotation was found to maintain anatomical movement.

Inderhaug et al. performed a biomechanical analysis of 12 cadaver knees with surgically-created ACL and ALL injuries, to assess the kinematic effects of LET procedures in combination with ACLR. The study found residual knee laxity in terms of both anterior translation and internal rotation following isolated intra-articular ACLR in patients that had an anterolateral lesion. ACLR combined with either the Lemaire or MacIntosh procedures, when performed at 30° of flexion with 20 N of tension at fixation, did restore native knee kinematics. Of particular note, they reported that fixation at greater than 20 N and a Lemaire technique with a graft superficial to the LCL both over constrained the knee during deep flexion. Interestingly, ALL reconstruction was not found to restore native knee kinematics, a finding contrary to most literature.

The modified Ellison procedure was evaluated by Devitt et al in a trial of twelve cadaveric knees. This technique is a distally based tenodesis in which a strip of ITB is elevated from Gerdy’s tubercle with a sliver of bone, or cartilaginous periosteum in the case of pediatric patients, reflected proximally, passed deep to the LCL, and reattached at the Gerdy’s tubercle. The technique was designed to limit constraint of natural knee kinematics, as the construct will tighten in extension, but not in flexion. Further, the technique has been proposed as a safe technique within the pediatric population as fixation at the proximal tibial epiphysis is thought to eliminate risk of physeal disruption.

Devitt et al. performed the modified Ellison technique on adult cadavers with intact ACLs in an attempt to provide findings relevant to the adolescent population. The group tested kinematics of the native knee, the knee following anterolateral capsule injury, and after the modified Ellison procedure. Their results showed that in ACL-intact knees, a surgically-created injury to the anterolateral capsule increased anterior drawer and internal rotation, but laxity returned to near-native values following the modified Ellison procedure. Notably, the procedure was found to over-constrain the knee during early range of knee flexion with decreased internal rotation noted up to 30 degrees of flexion.

Operative Technique

ACLR, including graft tensioning and fixation, is typically performed prior to LET. One technique, however, reports performing the LET subsequent to the ACL graft dissection, but prior to graft fixation. Lemaire, Ellison, and MacIntosh LET techniques have been described and used in both pediatric and adult patients. According to the previously mentioned survey collected from 87 practicing surgeons, among the 22 (34.9%) surgeons who perform LET in the primary setting, 18 (81.8%) preferred the modified Lemaire technique, 3 (13.6%) preferred the modified MacIntosh, and 1 (4.5%) performed a separate technique. In the revision ACLR setting, the number of surgeons who performed LET increased to 32 (50.8%), 28 (87.5%) of whom used the modified Lemaire technique, while the other 4 (12.5%) reported using the modified MacIntosh procedure.

The senior author’s preferred technique is a modified version of the Lemaire technique with a divergence in distal fixation, which will be described in further detail. The patient is in a supine position with a small bump under the affected hip. Following successful completion of the ACL reconstruction, attention is turned to the lateral extra-articular tenodesis. A longitudinal incision is made over the distal lateral femur from the origin of the lateral collateral ligament to a position equidistant between Gerdy’s tubercle and the fibular head ( Fig. 2 A). Dissection is then carried down to the ITB. A strip of ITB approximately 1 centimeter in width ( Fig. 2 B) is left attached distally at Gerdy’s tubercle and released proximally between 7.5 and 8 centimeters from the maintained attachment point. This 1-centimeter band is located slightly posterior to the middle of the ITB, providing a more robust portion of ITB.