The Anterolateral Ligament of the Knee: An Inconsistent Finding in Pediatric Cadaveric Specimens

A Cadaveric Study of the Optimal Isometric Region on the Anterolateral Surface of the Knee in Anterolateral Ligament Reconstruction

OBJECTIVE

Isolated intra-articular anterior cruciate ligament (ACL) reconstruction is not capable of restoring instability in many cases leading some to recommend concomitant anterolateral ligament (ALL) reconstruction. The satisfactory fixation site and graft length change are crucial in ligament reconstruction to restore the ALL function and avoid some unwanted graft behavior. The purpose of this investigation is to determine the optimal isometric region on the anterolateral aspect of the knee for ALL reconstruction using a three-dimensional optical instrument and a suture similar to an intraoperative isometric test.

METHODS

Six freshly frozen cadaveric human knees were used in this study. Data regarding the anterolateral surface were obtained using an optical measurement system to create a three-dimensional model. Nine points were selected on the femur (F1-F9) and tibia (Ta-Ti) respectively. The three-dimensional length change between each pair of tibial and femoral points was measured during passive knee flexion from 0° to 90° in 15° increments. Subsequently, five femoral points (A-E) were selected from the lateral femur, located in different areas relative to the lateral femoral epicondyle, and three tibial reference points (T1-T3) were selected in the isometric test. The changes in the length between each pair of reference points were measured using sutures. The 95% confidence interval for the rate of length change was estimated using the mean and standard deviation of the maximum rate of length change at different flexion angles, and the data were expressed as the mean (95% confidence interval) and compared with the maximum acceptable rate of change (10%).

RESULTS

The maximum acceptable change rate for ligament reconstruction is 10%, and the mean maximum rates and the 95% confidence interval (CI) of length change for the point combinations were calculated. Among all the combined points measured using the optical measurement system and the suture, the qualified point combination for reconstruction was F3 (8mm posterior and 8mm proximal to the lateral femoral epicondyle)-Tb (8mm proximal to the midpoint between the center of Gerdy's tubercle and the fibula head), A (posterior and proximal to the lateral femoral epicondyle)-T2 (10mm below the joint line)and A-T3 (15 mm below the joint line). The position of F3-Tb and A-T2 are close to each other.

CONCLUSION

The most isometric area of the femur for ALL reconstruction was posterior and proximal to the lateral femoral epicondyle. We recommend that the initial location of the femoral point be set at 8 mm posterior and 8 mm proximal to the lateral femoral epicondyle and the tibial point at approximately 10 mm below the joint line, midway between Gerdy's tubercle and fibular head, and subsequently adjusted to the most satisfactory position according to the isometric test.

Progress in research on and classification of surgical methods of arthroscopic reconstruction of the ACL and ALL using a shared tendon graft through the femoral tunnel

Anterior cruciate ligament (ACL) tear is a common clinical injury, and ACL reconstruction has reached a very mature stage. However, with the accumulation of cases, scholars have found that isolated ACL reconstruction may not completely solve the problem of knee rotational stability. With the increase in our understanding of knee joint structure, ACL combined with anterolateral ligament (ALL) reconstruction has become accepted by most scholars, and this operation has also achieved good clinical results. At present, there is no unified surgical method for ACL combined with ALL reconstruction. There are differences in bone tunnel location, reconstruction methods, and graft selection. Compared with the independent reconstruction of the ACL and ALL during the operation, shared tendon graft reconstruction of the ACL and ALL has the advantages of preserving tendon and avoiding tunnel convergence. So far, there is no relevant literature summarizing the reconstruction of the ACL and ALL with a shared tendon graft. This paper reviews the anatomic study of the ALL, the study of isometric points, surgical indications, and surgical methods and their classification for shared tendon graft reconstruction of the ACL and ALL.

The Anterolateral Ligament of the Knee in Pediatric Patients: What Do We Know? A Scoping Review

The knowledge on the anatomy, function and biomechanics and the role of surgical procedures on the anterolateral ligament (ALL) of the knee is still controversial. Only a few papers have examined the ALL in children. The aim of this review is to analyze all the available literature about ALL in the pediatric population. Following the PRISMA criteria, the literature was systematically reviewed, examining all the articles about ALL in pediatric patients. Eight articles were involved in this study. Five cadaveric studies, two diagnostic studies, and one cross-sectional study were found. The identification of the ALL is not always possible in diagnostic studies using magnetic resonance (MRI) or in dissecting specimens. A high variability in the presence of the ligament and in its origin and insertion were found among the studies. It is more difficult to identify the ligament in younger patients than in older children, suggesting that its presence may develop at some point during the growth. Further studies are needed for a detailed knowledge of the ALL.

Distance to the Neurovascular Bundle for Iliotibial Band Graft Passage During Anterior Cruciate Ligament Reconstruction: A Pediatric Cadaveric Study

Background:

The Micheli technique for anterior cruciate ligament (ACL) reconstruction (ACLR) has proven to be a reliable method with a minimal risk for growth disturbance among skeletally immature patients.

Purposes:

To evaluate the Micheli technique of iliotibial band (ITB) graft passage for ACLR using cadaveric knee models and to measure the distance between the surgical instrument tip and the neurovascular bundle in the posterior knee joint: specifically, the peroneal nerve, tibial nerve, and popliteal artery.

Study Design:

Descriptive laboratory study.

Methods:

Gross dissection was performed on 17 pediatric cadaveric knees (12 male and 5 female) aged between 4 and 12 years. To simulate ITB graft passage, we passed a curved-tip hemostat clamp through the posterior capsule, with the knee flexed from 90° to 100°. Next, clinical photographs were taken, and digital imaging software was used to measure the distance in centimeters from the clamp tip to each respective neurovascular structure.

Results:

The mean distances from the clamp tip to the tibial nerve, popliteal artery, and peroneal nerve were 0.875 cm (range, 0.468-1.737 cm), 0.968 cm (range, 0.312-1.819 cm), and 1.149 cm (range, 0.202-2.409 cm), respectively. Mean values were further calculated for age groups of ≤8, 9-10, and 11-12 years. The mean distance from the clamp tip to the peroneal nerve was 1.400 cm larger for 11- to 12-year-old specimens than for ≤8-year-old specimens (95% CI, 0.6-2.2 cm; P = .005).

Conclusion:

The neurovascular structures in the posterior knee were in close proximity to the path of graft passage, with distances <1 cm in many specimens in this study. When passing the graft through the knee for an over-the-top position, surgeons should consider these small distances between the path of graft passage and critical neurovascular structures.

Clinical Relevance:

As the incidence of ACL tears is continuously increasing within the pediatric population, there are a larger number of ACLR procedures being performed. Although neurovascular injuries during ACLR are rare, this study clarifies the close proximity of neurovascular structures during ITB graft passage using the Micheli technique of ACLR.

Pediatric Revision Anterior Cruciate Ligament Reconstruction: Current Concepts Review

OBJECTIVE

We present a review of revision anterior cruciate ligament (ACL) reconstruction in pediatric patients, discussing risk factors for rerupture, physical examination and imaging, treatment principles and surgical techniques, postoperative rehabilitation, and clinical outcomes.

DATA SOURCES

PubMed, Cochrane, and Embase databases were queried for relevant articles about revision ACL topics. All types of manuscripts, including clinical studies, basic science studies, case series, current concepts reviews, and systematic reviews were analyzed for relevant information. Current concepts on risk factors for rerupture, physical examination and imaging, treatment principles and surgical techniques, postoperative rehabilitation, and clinical outcomes were synthesized.

MAIN RESULTS

Surgical treatment should be individualized, and the graft type, fixation devices, tunnel placement, and complementary procedures (eg, extra-articular tenodesis) should be tailored to the patient's needs and previous surgeries. Rehabilitation programs should also be centered around eccentric strengthening, isometric quadriceps strengthening, active flexion range of motion of the knee, and an emphasis on closed chain exercises. Despite adherence to strict surgical and postoperative rehabilitation principles, graft refailure rate is high, and return to sports rate is low.

CONCLUSION

Rerupture of the ACL in the pediatric population is a challenging complication that requires special attention. Diagnostic evaluation of repeat ACL ruptures is similar to primary injuries. Although outcomes after revision ACL reconstruction are expectedly worse than after primary reconstruction, athletes do return to sport after proper rehabilitation. Further research is needed to continue to improve outcomes in this high-risk population, aimed at continued knee stability, graft survivorship, and improved quality of life.

The anterolateral ligament of the knee is not a solid structure in human fetuses

PURPOSE

The purpose of this study was to investigate if the anterolateral ligament of the knee (ALL) is present in the human fetus and describe its topography along with other structures of the region.

METHODS

Forty human fetuses knee joints, at mean age 34 weeks (± 2.57 weeks), fixed in 10% formalin, were submitted to cross-sectional dissection and mesoscopic analysis.

RESULTS

The ALL was not identified, although the usual topography of the region was identified in all specimens: skin, subcutaneous tissue, iliotibial tract (ITT), fibular collateral ligament, popliteal muscle tendon, lateral meniscus, patellar ligament, infrapatellar fat pad, lateral patellar retinaculum, knee joint capsule, lateral inferior genicular vessels, and the biceps femoris tendon. The ITT reveals anterior (n = 12) and lateral thickening (n = 17) in some specimens. This thickening was found in both knees of the same subject in 6/20 specimens.

CONCLUSION

The anterolateral ligament of the knee is not a congenital or solid structure. Our results suggest that the ALL may be a deep layer of the ITT or part of the knee joint capsule, or its identification is evaluator dependent.

The Anterolateral Ligament of the Knee

The femoral attachment of the anterolateral ligament (ALL) of the knee is still under debate, but the tibial attachment is consistently between Gerdy's tubercle and the fibular head. The structure is less identifiable and more variable in younger patients. The ALL likely plays a role in rotational stability, but its impact on anterior stability is less clear. Numerous ALL reconstruction techniques have been described. Biomechanical analysis of these techniques has not shown clear benefits, but this literature is limited by the heterogeneity of techniques, graft choices, and study methodology. Clinical studies of combined anterior cruciate ligament (ACL) and ALL reconstruction are few but promising in lowering the risk of an ACL reinjury. To our knowledge, there are no studies showing the clinical outcomes of combined ACL and ALL reconstruction in pediatric patients, who are at higher risk for ACL graft failure than adults.

Combined Anterolateral Ligament Reconstruction and Capsular Reinforcement in the Skeletally Immature Knee

Graft failure after anterior cruciate ligament reconstruction remains a challenging complication in the pediatric population. The anterolateral ligament (ALL) contributes to rotational stability, and early evidence in adults suggests that ALL reconstruction may lower the risk of anterior cruciate ligament graft rupture. We present a technique for combined ALL reconstruction and anterolateral capsular reinforcement using iliotibial band autograft in skeletally immature patients. This procedure seeks to provide additional rotational stability in varying degrees of flexion while avoiding the physes and eliminating the need for implants.

Truly Existing or Hyped up? Unravelling the Current Knowledge Regarding the Anatomy, Radiology, Histology and Biomechanics of the Enigmatic Anterolateral Ligament of the Knee Joint

Ever since its description, anterolateral ligament (ALL) of the knee joint remains as the hotspot of controversies. Though it has been described under various descriptions, the structure gained its limelight when it was christened as anterolateral ligament by Claes in 2013. The main reason for the controversies around it is the lack of concrete evidences regarding its attachments, morphology, biomechanical aspects and radiological appearance. Similarly the role of ALL in pivot shift phenomenon also remains as a point of debate. The advocates of ALL suggest that because of its ability to modulate internal rotation and attachment to the lateral meniscus, ALL contributes to the pivot shift phenomenon. Similarly, the orientation of ALL stands as the reason for varied documentation with respect to imaging techniques. With the growing body of evidence, it is imperative to fix our stand regarding the structure because, if found to be morphologically persistent, it can be used for concomitant anterolateral stabilization along with anterior cruciate ligament reinforcement surgeries. The present review tries to systematically review the anatomy, variations in classifications, descriptions, histology, radiology and biomechanical features of ALL. At the end of the review, we would like to find the answer for the question: Is ALL a distinct ligamentous structure located at the anterolateral aspect of the knee? What is the contribution of it to the tibial internal rotation stability?

Anterior Cruciate Ligament Re-tear and Revision Reconstruction in the Skeletally Immature Athlete

PURPOSE OF REVIEW

With an increase in high-demand sporting activity, the rate of pediatric and adolescent anterior cruciate ligament (ACL) reconstruction is increasing. Yet, the failure rates after reconstruction are much higher than the adult population. The purpose of this paper is to understand failure rates, reasons for graft failure, and strategies for successful revision surgery.

RECENT FINDINGS

A complete understanding of the failure etiology is essential for the clinician treating this population prior to revision. This begins with an assessment of post-operative patient compliance and sporting activity. Surgical technique must then be scrutinized for non-anatomic tunnel placement and poor graft size/type. Concurrent bony deformity must also be addressed including lower extremity valgus alignment and tibial slope abnormalities. Meniscus and chondral injury must be aggressively treated. Furthermore, imaging must be examined to look for missed posterolateral corner injury. Lateral extra-articular tenodesis (in the setting of ligamentous laxity or rotational instability) may be also indicated as well. The surgeon can then choose a graft type and surgical technique that optimizes outcome and respects skeletal growth. Prior to surgical intervention, the clinician must also counsel patients in regard to the guarded prognosis and outcomes in this setting. Prolonged rehabilitation protocols/return-to-play timing as well as sporting activity modification in the post-operative period after revision are critical. There is limited literature on revision ACL reconstruction in the skeletally immature athlete. An understanding of all the risk factors for failure is essential in order to achieve treatment success.

Biomechanical Evaluation of Pediatric Anterior Cruciate Ligament (ACL) Reconstruction Techniques With and Without the Anterolateral Ligament (ALL)

BACKGROUND

Two popular physeal-sparing procedures used in the management of anterior cruciate ligament (ACL) injuries in skeletally immature patients are the iliotibial band (ITB) ACL reconstruction (ACLR) and the all-epiphyseal (AE) ACLR. Although there has been concern for overconstraint of the lateral compartment of the knee with the ITB ACLR technique, rotational stability, as provided by the anterolateral ligament (ALL) and ACL, has not been assessed in the setting of pediatric ACLR techniques. Our hypothesis is that the ITB ACLR and AE ACLR with ALL reconstruction (ALLR) will best replicate the biomechanical profile of the intact ACL that is lost with transection of the ACL and ALL.

METHODS

Eight cadaveric legs were statically loaded with an anterior drawer force and varus, valgus, internal and external rotational moments at 0, 30, 60, and 90 degrees of flexion. Displacement and rotation were recorded in the following conditions: intact ACL/intact ALL, ACL-deficient/intact ALL, ITB ACLR/intact ALL, ITB ACLR/ALL-deficient, ACL-deficient/ALL-deficient, AE ACLR/ALL-deficient, AE ACLR/ALLR.

RESULTS

Both ACLR techniques reduced anterior tibial translation from the ACL-deficient state, but neither restored it to the intact state (P<0.05), except in full extension. ALL deficiency increased anterior tibial translation in the ACL-deficient state (P<0.05). In rotational testing, no significant increase was seen with transection of the ACL, but the ACL-deficient/ALL-deficient state had a significant increase in internal rotation (P<0.05). This was significantly restored to the intact state at most flexion angles with the ITB ACLR without rotational overconstraint of the lateral compartment. The AE ACLR/ALL-deficient state and AE ACLR/ALLR improved rotational stability at lower flexion angles, but not at 60 and 90 degrees. There were no significant changes in varus/valgus moments.

CONCLUSIONS

In this model, the ITB ACLR provided the superior biomechanical profile between our tested reconstructions. It best corrected both AP and rotatory stability without overconstraining the knee. The AE ACLR and AE ACLR/ALLR improved both parameters but not at all flexion angles and not as robustly. ACL deficiency in the knee increased anterior tibial translation, but did not affect rotatory stability. ALL deficiency in the knee increased anterior displacement and rotational moments in the ACL-deficient state.

CLINICAL RELEVANCE

Cadaveric Laboratory Study. The ITB ACLR seems to be the biomechanically superior pediatric ACLR technique to regain translational and rotational stability.

Ultrastructural Assessment of the Anterolateral Ligament

Background:

The anterolateral ligament (ALL) has been identified as a structure on the lateral side of the knee, but debate exists regarding whether it is a capsular thickening or a ligament.

Hypothesis:

A detailed ultrastructural characterization of the ALL and its ultrastructure collagen arrangement will reveal it more closely resembles ligamentous tissue than joint capsule.

Study Design:

Descriptive laboratory study.

Methods:

Eight paired knee samples from 4 fresh-frozen male cadavers were used for this study. Samples were harvested from the ALL, the joint capsule, and the medial collateral ligament (MCL). All samples were evaluated with light microscopy (LM), transmission electron microscopy (TEM), and variable pressure scanning electron microscopy (VP-SEM). With LM, the 3 tissues were analyzed and their morphology described. With TEM, the ultrastructure and collagen characteristics were quantified and compared among specimens. Then, the 3-dimensional characteristics were compared with VP-SEM.

Results:

Ultrastructure analysis demonstrated similar morphology between the ALL and MCL, with significant differences in these 2 structures as compared with the joint capsule. On LM, the ALL and MCL were characterized by the presence of a dense collagen fiber oriented in the longitudinal and transversal directions of the fiber bundles, while the joint capsule was found to have a more disorganized architecture. On TEM, the collagen fibers of the ALL and MCL demonstrated similar ultrastructural morphology, with both having collagen fibers in parallel, longitudinal alignment. A quantitative analysis was also performed, with the mean (± SD) diameter of fibrils in the ALL and MCL being 80 ± 2.66 nm and 150 ± 3.35 nm, respectively (all P < .001). The VP-SEM highlighted that ALL and MCL morphology demonstrated arrangements of fiber bundles that are densely packed and organized, in contrast to the disorganized fibers of the joint capsule.

Conclusion:

The ALL and MCL have comparable ultrastructures that are distinctly different from the joint capsule, as visualized on LM, TEM, and VP-SEM.

Clinical Relevance:

The ALL should be considered a distinctive structure of the knee, although strictly connected to the surrounding capsule.

The anterolateral ligament of the knee and the lateral meniscotibial ligament - Anatomical phantom versus constant structure within the anterolateral complex

BACKGROUND

Concerning the ongoing controversy about the existence and nature of the anterolateral ligament (ALL) of the knee joint, we reinvestigated the formation of the anterolateral part of its fibrous capsule in anatomic specimens. Furthermore, we wanted to clarify if the lateral meniscus has established a constant anchoring to the lateral tibial condyle via a lateral meniscotibial ligament (lmtl).

METHODS

Forty paired embalmed lower extremities taken from 20 human body donors (15 men and five women) underwent exact macroscopic dissection. For the detailed evaluation of the lmtl, additionally 12 specially dissected joint specimens were used. In two of these specimens, the lmtl underwent further histological examination.

RESULTS

In all specimens, the anterolateral part of the knee joint fibrous capsule was established by the iliotibial tract and the anterior arm of the aponeurosis of the biceps femoris muscle. According to their close connection and the fact that the anterolateral part of the fibrous capsule is exclusively assembled by these two aponeuroses, they do not leave any space for a distinct ALL connecting the lateral femoral epicondyle and the lateral tibial condyle. The constantly present lmtl was identified as a flat, rectangular bundle of collagen and also elastic fibers reinforcing the inner aspect of the fibrous capsule. Following an oblique direction, it connected the lateral face of the lateral meniscus with the superolateral margin of the lateral tibial condyle. The lmtl measured, on average, 17.1mm in longitudinal and 13mm in anteroposterior direction.

CONCLUSION

Our results show that there is no evidence for the existence of an ALL in human knee joints. It is represented either by the iliotibial tract or - most likely - by the anterior arm of the short head of the biceps femoris muscle. On the other hand, the lmtl was found to be a constantly present structure.

Editorial Commentary: Anterolateral Ligament-Anatomy, Evaluation, and Future Applications to Knee Stability

Magnetic resonance imaging evaluation of anterolateral ligament injury may be reliable for individuals experienced and trained to identify it, but it does not reference a diagnostic gold standard. The structural anatomy and radiographic diagnosis may differ from those of more traditional ligaments, which should influence concepts of reconstruction.

The anatomy of the anterolateral structures of the knee - A histologic and macroscopic approach

BACKGROUND

The anatomy of the anterolateral structures of the knee is complex and still controversial. The aim of our study was to analyze this anatomy by histologic and macroscopic evaluation, with a particular emphasis on the anterolateral ligament (ALL).

MATERIAL AND METHODS

Twenty-three cadaveric knee joints were dissected followed by a qualitative and quantitative anatomic analysis of the anterolateral knee structures. Histology and comparison of different anterolateral structures was performed in addition.

RESULTS

The ALL was identified in all of the dissected cadaveric knee specimens. It runs in an oblique course from its proximo-dorsal insertion at the distal femur into a ventro-distal direction to the anterolateral tibia. The femoral insertion site was found to be posterior and slightly proximal to the lateral femoral epicondyle and the femoral attachment of the lateral collateral ligament (LCL). The femoral insertion of the ALL overlapped the LCL in all dissected knees. The tibial insertion site was midway between Gerdy's tubercle (GT) and the tip of the fibular head (FH). In 15 of the dissected 23 knee joints, thin attachments to the lateral meniscus were observed. Histology confirmed differences in the composition of the anterolateral knee joint capsule, the ALL and the iliotibial band (ITB).

CONCLUSIONS

The ALL occurs as a regular separate anterolateral ligamentous structure. It is distinguishable from the ITB and the anterolateral joint capsule in both embalmed and non-embalmed specimens. Histology of the ALL indicates typical ligamentous tissue which clearly differs from the anterolateral knee joint capsule and the thicker ITB.

LEVEL OF EVIDENCE

Level II, descriptive anatomic study.

Anterolateral ligament of the knee: a step-by-step dissection

Background

The number of studies and clinical interest in the anterolateral ligament of the knee (ALL) has grown in recent years. A meticulous and accurate ALL dissection is vital in anatomic and biomechanical studies, and a standardized technique is not yet established. As such, the aim of this study was to describe a step-by-step ALL dissection technique that could help authors consistently identify the ALL.

Methods

Twenty knees from frozen adult cadavers, with no preference for sex or age, were included in the study. All the cadavers were dissected using the same technique to determine the incidence of the ALL.

Results

A transverse incision is performed in the iliotibial band (ITB), around 10 cm proximal to the topography of the lateral epicondyle of the femur. Next, the ITB undergoes anterograde blunt dissection until its insertion at Gerdy’s tubercle in the tibia. Maintaining biceps femoris insertion, a dissection is performed anteriorly to it, until the lateral collateral ligament (LCL) is found. Using the LCL, internal rotation and 30 to 60° flexion as references, the ALL can be located in the anterolateral topography of the knee, with its origin near the lateral epicondyle (proximal and posterior) and insertion between Gerdy’s tubercle and the fibula (4.0 mm to 7.0 mm below the tibial plateau), expanding to the lateral meniscus (between the body and anterior horn), exhibiting a mean length of 4.0 ± 0.4 cm and mean width of 5.5 ± 0.8 mm.

Conclusions

The present article describes an effective and reproducible ALL dissection technique that made it was possible to identify the ligament in 100% of the cases in the present study.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2517-0) contains supplementary material, which is available to authorized users.

Lateral Augmentation Procedures in Anterior Cruciate Ligament Reconstruction: Anatomic, Biomechanical, Imaging, and Clinical Evidence

BACKGROUND

There has been an increasing interest in lateral-based soft tissue reconstructive techniques as augments to anterior cruciate ligament reconstruction (ACLR). The objective of these procedures is to minimize anterolateral rotational instability of the knee after surgery. Despite the relatively rapid increase in surgical application of these techniques, many clinical questions remain.

PURPOSE

To provide a comprehensive update on the current state of these lateral-based augmentation procedures by reviewing the origins of the surgical techniques, the biomechanical data to support their use, and the clinical results to date.

STUDY DESIGN

Systematic review.

METHODS

A systematic search of the literature was conducted via the Medline, EMBASE, Scopus, SportDiscus, and CINAHL databases. The search was designed to encompass the literature on lateral extra-articular tenodesis (LET) procedures and the anterolateral ligament (ALL) reconstruction. Titles and abstracts were reviewed for relevance and sorted into the following categories: anatomy, biomechanics, imaging/diagnostics, surgical techniques, and clinical outcomes.

RESULTS

The search identified 4016 articles. After review for relevance, 31, 53, 27, 35, 45, and 78 articles described the anatomy, biomechanics, imaging/diagnostics, surgical techniques, and clinical outcomes of either LET procedures or the ALL reconstruction, respectively. A multitude of investigations were available, revealing controversy in addition to consensus in several categories. The level of evidence obtained from this search was not adequate for systematic review or meta-analysis; thus, a current concepts review of the anatomy, biomechanics, imaging, surgical techniques, and clinical outcomes was performed.

CONCLUSION

Histologically, the ALL appears to be a distinct structure that can be identified with advanced imaging techniques. Biomechanical evidence suggests that the anterolateral structures of the knee, including the ALL, contribute to minimizing anterolateral rotational instability. Cadaveric studies of combined ACLR-LET procedures demonstrated overconstraint of the knee; however, these findings have yet to be reproduced in the clinical literature. The current indications for LET augmentation in the setting of ACLR and the effect on knee kinematic and joint preservation should be the subject of future research.

Anatomy of the Anterolateral Ligament of the Knee: A Systematic Review

PURPOSE

To conduct a systematic literature review to search for studies on the anatomy of the anterolateral ligament (ALL) of the knee, presenting the most accepted findings, as well as the evolution of anatomic information on this structure.

METHODS

We reviewed the PubMed, MEDLINE, and ClinicalKey databases for anatomic studies on the ALL, involving cadaveric, histologic, and biochemical dissection and/or anatomic imaging. The primary data researched were the presence of the ligament; measures of length, width, and thickness; ligament path; insertions; number of bands; histologic assessment; and innervation.

RESULTS

We identified 53 studies. The ALL was found in 82.87% of adult dissections (more easily visualized in fresh cadavers), 74.07% of fetal dissections, and 84.80% of magnetic resonance imaging (MRI) studies. In 29 articles, the ALL was found in 100% of cases. There are 3 ALL insertion points: femoral, tibial, and meniscal. Histologic sections showed dense, well-organized collagen fibers, with an average of 121 fibroblasts/mm² in adults, in addition to the presence of vascular and nervous tissue. MRI was shown to be a good examination tool to visualize the ALL, primarily in the coronal plane and with T2-weighted images.

CONCLUSIONS

The ALL is a distinct structure in the anterolateral portion of the knee. It exhibits typical ligament characteristics and can be visualized on imaging examinations, especially MRI. It has a femoral attachment near the lateral epicondyle, with a trend in recent years showing it to be located posterior and proximal to it, following an anteroinferior trajectory, with an insertion into the lateral meniscus and proximal tibia at the midpoint between the fibular head and Gerdy tubercle. Among the studies, the length of the ALL varied from 30.41 to 59.0 mm, the width ranged between 4.0 and 7.0 mm, and the thickness ranged between 1.0 and 2.0 mm.

CLINICAL RELEVANCE

During the past few years, much controversy has been raised about the correct anatomy of the ALL. The main clinical relevance of this study is not only to end the discussion about the ALL's existence but also to clarify and synthesize the main evidence on the ALL's anatomy, mainly the currently most accepted attachments according to the recent literature, to enable more precise development of biomechanical settings and surgical techniques.

An Overview of Anatomy and Imaging of the Anterolateral Structures of the Knee

Despite several previous articles in the literature, never before have so many studies with regard to anterolateral knee structures been performed. The anterolateral knee complex consists briefly of the iliotibial band, with its proximal and distal attachments, the joint capsule, and the anterolateral ligament (ALL). The recently introduced ALL has several different descriptions, making it difficult to build a consensus with regard to its anatomy. An extensive description of these structures, particularly the iliotibial band and the ALL, with regard to anatomy and imaging, will be provided in this article.

Anatomic and Histological Study of the Anterolateral Aspect of the Knee: A SANTI Group Investigation

Background:

The structure and function of the anterolateral aspect of the knee have been significantly debated, with renewed interest in this topic since the description of the anterolateral ligament (ALL).

Purpose:

To define and describe the distinct structures of the lateral knee and to correlate the macroscopic and histologic anatomic features.

Study Design:

Descriptive laboratory study.

Methods:

Twelve fresh-frozen human cadavers were used for anatomic analysis. In the left knee, a layer-by-layer dissection and macroscopic analysis were performed. In the right knee, an en bloc specimen was obtained encompassing an area from the Gerdy tubercle to the posterior fibular head and extending proximally from the anterior aspect to the posterior aspect of the lateral femoral epicondyle. The en bloc resection was then frozen, sliced at the level of the joint line, and reviewed by a musculoskeletal pathologist.

Results:

Macroscopically, the lateral knee has 4 main layers overlying the capsule of the knee: the aponeurotic layer, the superficial layer including the iliotibial band (ITB), the deep fascial layer, and the ALL. Histologically, 8 of 12 specimens demonstrated 4 consistent, distinct structures: the ITB, the ALL, the lateral collateral ligament, and the meniscus.

Conclusion:

The lateral knee has a complex orientation of layers and fibers. The ALL is a distinct structure from the ITB and is synonymous to the previously described capsulo-osseous layer of the ITB.

Clinical Relevance:

Increasingly, lateral extra-articular procedures are performed at the time of anterior cruciate ligament reconstruction. Understanding the anatomic features of the anterolateral aspect of the knee is necessary to understand the biomechanics and function of the structures present and allows surgeons to attempt to replicate those anatomic characteristics when performing extra-articular reconstruction.

Magnetic resonance imaging assessment of the normal knee anterolateral ligament in children and adolescents

OBJECTIVE

To characterize the anterolateral ligament (ALL) in normal knees of pediatric patients by magnetic resonance imaging (MRI) and to establish the age at which it is possible to visualize its presence and whether there are differences between male and female populations.

MATERIALS AND METHODS

MRI scans of patients younger than 18 years were retrospectively evaluated. The exams were performed in 1.5-T scanners. The ALL was characterized dichotomously as visualized or not visualized based on the assessment criteria of this structure in adult patients. The characterization of the ALL was divided according to sex and age.

RESULTS

A total of 363 knee MRI scans were evaluated, 200 from male and 163 from female patients. The ALL was more frequently visualized in coronal sequences. The mean ALL visualization in pediatric patients was 69.4% and was lower in younger patients and higher in patients close to 18 years. It was not possible to visualize the ALL in female patients younger than 7 years or in male patients younger than 6 years. In patients between 17 and 18 years of age, the ALL was visualized in 100% of cases in both sexes.

CONCLUSIONS

Visualization of the ALL increased with age in both sexes. Only after age 13 in females and age 15 in males was visualization of the ALL close to 70%; thus, below these ages, we believe that the characterization of this structure with conventional protocols is still imprecise.

The prevalence and morphological characteristics of the knee anterolateral ligament in a Chinese population

The anterolateral ligament, a distinct structure connecting the lateral femoral epicondyle to the anterolateral proximal tibia, is gaining attention because of its possible function in ensuring internal rotational stability of the tibia. To study the prevalence and precise anatomical characteristics of the anterolateral ligament and its relationship to adjacent structures in a Chinese population, a total of 20 amputated knee specimens were collected. The anterolateral regions of the knees underwent detailed surgical dissection, followed by precise measurement of the anterolateral ligament and its adjacent structures. Histological analysis of the anterolateral ligament was performed using hematoxylin and eosin (H&E) staining. A thin soft tissue deep to the iliotibial band running obliquely across the lateral fibula ligament and connecting the lateral head of the gastrocnemius with the tibia, termed the 'gastrocnemius-tibial ligament' or superficial layer of the anterolateral ligament, was observed in 18 of the 20 specimens, corresponding to a prevalence of 90%. Furthermore, a well-defined anterolateral ligament deep to the gastrocnemius-tibial ligament and distinct from the lateral fibula ligament was found in all 20 knees (prevalence, 100%). The independent gastrocnemius-tibial ligament and anterolateral ligament had separate femoral originations at the lateral head of the gastrocnemius and the lateral femoral epicondyle, and the same osseous tibial insertion at the midpoint between Gerdy's tubercle and the most lateral aspect of the fibular head. H&E staining showed that both the anterolateral ligament and gastrocnemius-tibial ligament were ligaments consisting of collagenous bundles. In the Chinese Han population, the gastrocnemius-tibial ligament and anterolateral ligament may form a complex at the anterolateral aspect of the knee, which is likely involved in ensuring the internal rotational stability of the tibia.

All-Epiphyseal Anterior Cruciate Ligament Femoral Tunnel Drilling: Avoiding Injury to the Physis, Lateral Collateral Ligament, Anterolateral Ligament, and Popliteus-A 3-Dimensional Computed Tomography Study

PURPOSE

To investigate the relation of the at-risk structures (distal femoral physis, lateral collateral ligament, anterolateral ligament, popliteus, and articular cartilage) during all-epiphyseal femoral tunnel drilling. A second purpose was 2-fold: (1) to develop recommendations for tunnel placement and orientation that anatomically reconstruct the anterior cruciate ligament (ACL) while minimizing the risk of injury to these at-risk structures, and (2) to allow for maximal tunnel length to increase the amount of graft in the socket to facilitate healing.

METHODS

Three-dimensional models of 6 skeletally immature knees (aged 7-11 years) were reconstructed from computed tomography and used to simulate all-epiphyseal femoral tunnels. Tunnels began within the ACL footprint and were directed laterally or anterolaterally, with the goal of avoiding injury to at-risk structures. The spatial relation between the ideal tunnel and these structures was evaluated. Full-length tunnels and partial length condyle sockets were simulated in the models using the same trajectories.

RESULTS

An anterolateral tunnel could be placed to avoid direct injury to lateral structures. The safe zone on the anterolateral aspect of the femur was larger than that of a tunnel with a direct lateral trajectory (median 127 mm² vs 83 mm², P = .028). Anterolateral tunnels were longer than direct lateral tunnels (median 30 mm vs 24 mm, P = .041). Safe angles for anterolateral tunnels were 34° to 40° from the posterior condylar axis; direct lateral tunnels were drilled 4° to 9° from the posterior condylar axis. Sockets could be placed without direct injury to structures at risk with either orientation.

CONCLUSIONS

An all-epiphyseal ACL femoral tunnel can be placed without causing direct injury to at-risk structures. A tunnel angled anterolaterally from the ACL origin is longer and has a larger safe zone compared with the direct lateral tunnel.

CLINICAL RELEVANCE

The largest safe zone for femoral all-epiphyseal ACL drilling was (1) anterior to the lateral collateral ligament origin, (2) distal to the femoral physis, and (3) proximal to the popliteus tendon origin. A direct lateral tunnel may also be used, but has a smaller safe zone. Sockets or partial length tunnels may have a lower risk of injury to at-risk structures.

Current Concepts of the Anterolateral Ligament of the Knee: Anatomy, Biomechanics, and Reconstruction

In 1879, Paul Segond described an avulsion fracture (now known as a Segond fracture) at the anterolateral proximal tibia with the presence of a fibrous band at the location of this fracture. Although references to this ligament were occasionally made in the anatomy literature after Segond's discovery, it was not until 2012 that Vincent et al named this ligament what we know it as today, the anterolateral ligament (ALL) of the knee. The ALL originates near the lateral epicondyle of the distal femur and inserts on the proximal tibia near Gerdy's tubercle. The ALL exists as a ligamentous structure that comes under tension during internal rotation at 30°. In the majority of specimens, the ALL can be visualized as a ligamentous structure, whereas in some cases it may only be palpated as bundles of more tense capsular tissue when internal rotation is applied. Biomechanical studies have shown that the ALL functions as a secondary stabilizer to the anterior cruciate ligament (ACL) in resisting anterior tibial translation and internal tibial rotation. These biomechanical studies indicate that concurrent reconstruction of the ACL and ALL results in significantly reduced internal rotation and axial plane tibial translation compared with isolated ACL reconstruction (ACLR) in the presence of ALL deficiency. Clinically, a variety of techniques are available for ALL reconstruction (ALLR). Current graft options include the iliotibial (IT) band, gracilis tendon autograft or allograft, and semitendinosus tendon autograft or allograft. Fixation angle also varies between studies from full knee extension to 60° to 90° of flexion. To date, only 1 modern study has described the clinical outcomes of concomitant ALLR and ACLR: a case series of 92 patients with a minimum 2-year follow-up. Further studies are necessary to define the ideal graft type, location of fixation, and fixation angle for ALLR. Future studies also must be designed in a prospective comparative manner to compare the clinical outcomes of patients undergoing ACLR with ALL reconstruction versus without ALL reconstruction. By discovering the true effect of the ALL, investigators can elucidate the importance of ALLR in the setting of an ACL tear.

The Anterolateral Ligament is Not the Whole Story: Reconsidering the Form and Function of the Anterolateral Knee and its Contribution to Rotatory Knee Instability

The heterogeneity of available cadaveric, histologic, and radiographic results related to the anterolateral ligament (ALL) does not support its existence as a discrete anatomic structure. Moreover, focusing narrowly on the ALL in isolation, what has previously been referred to as “ALL myopia,” obscures a thorough appreciation for the stability contributions of both capsular and extracapsular structures. We consider injury to the soft tissues of the anterolateral knee–the anterolateral complex—just one component of what is frequently found to be a spectrum of pathology observed in the rotationally unstable, anterior cruciate ligament (ACL)-deficient knee. Increased lateral tibial slope, meniscal root tears, and “ramp” lesions of the medial meniscocapsular junction have all been implicated in persistent rotatory knee instability, and the restoration of rotational stability requires a stepwise approach to the assessment of each of these entities. Through an appreciation for the multifactorial nature of rotatory knee instability, surgeons will be better equipped to perform durable ACL reconstructions that maximize the likelihood of optimal clinical outcomes for patients. The purposes of this review are to provide an update on the relevant anatomy of the anterolateral knee soft tissues and to explain the multifactorial nature of rotatory knee instability in the setting of ACL deficiency.

Update on Anterior Cruciate Ligament Rupture and Care in the Female Athlete

As female athlete sports participation has continued to increase, the rate of anterior cruciate ligament (ACL) rupture in female athletes has also increased. Individualized, patient-specific treatment is crucial to achieving optimal outcomes; ACL reconstruction must accurately restore native ACL anatomy and address any concomitant injury to secondary stabilizers. Rehabilitation programs should target hip, core, and trunk neuromuscular control; allow adequate time for graft ligamentization; and address the psychosocial needs of the athlete.

Anterolateral Ligament of the Knee Shows Variable Anatomy in Pediatric Specimens

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction failure rates are highest in youth athletes. The role of the anterolateral ligament in rotational knee stability is of increasing interest, and several centers are exploring combined ACL and anterolateral ligament reconstruction for these young patients. Literature on the anterolateral ligament of the knee is sparse in regard to the pediatric population. A single study on specimens younger than age 5 years demonstrated the presence of the anterolateral ligament in only one of eight specimens; therefore, much about the prevalence and anatomy of the anterolateral ligament in pediatric specimens remains unknown.

QUESTIONS/PURPOSES

We sought to (1) investigate the presence or absence of the anterolateral ligament in prepubescent anatomic specimens; (2) describe the anatomic relationship of the anterolateral ligament to the lateral collateral ligament; and (3) describe the anatomic relationship between the anterolateral ligament and the physis.

METHODS

Fourteen skeletally immature knee specimens (median age, 8 years; range, 7-11 years) were dissected (12 male, two female specimens). The posterolateral structures were identified in all specimens, including the lateral collateral ligament and popliteus tendon. The presence or absence of the anterolateral ligament was documented in each specimen, along with origin, insertion, and dimensions, when applicable. The relationship of the anterolateral ligament origin to the lateral collateral ligament origin was recorded.

RESULTS

The anterolateral ligament was identified in nine of 14 specimens. The tibial attachment point was consistently located in the same region on the proximal tibia, between the fibular head and Gerdy's tubercle; however, the femoral origin of the anterolateral ligament showed considerable variation with respect to the lateral collateral ligament origin. The median femoral origin of the anterolateral ligament was 10 mm (first interquartile 6 mm, third interquartile 13) distal to the distal femoral physis, whereas its median insertion was 9 mm (first interquartile 5 mm, third interquartile 11 mm) proximal to the proximal tibial physis.

CONCLUSIONS

The frequency of the anterolateral ligament in pediatric specimens we observed was much lower than other studies on adult specimens; future studies might further investigate the prevalence, development, and functional role of the anterolateral ligament of the knee.

CLINICAL RELEVANCE

This study expands our understanding of the anterolateral ligament and provides important anatomic information to surgeons considering anterolateral ligament reconstruction concomitantly with primary or revision ACL reconstruction in pediatric athletes.

Anatomic and Histological Investigation of the Anterolateral Capsular Complex in the Fetal Knee

BACKGROUND

There is currently disagreement with regard to the presence of a distinct ligament in the anterolateral capsular complex of the knee and its role in the pivot-shift mechanism and rotatory laxity of the knee.

PURPOSE

To investigate the anatomic and histological properties of the anterolateral capsular complex of the fetal knee to determine whether there exists a distinct ligamentous structure running from the lateral femoral epicondyle inserting into the anterolateral tibia.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twenty-one unpaired, fresh fetal lower limbs, gestational age 18 to 22 weeks, were used for anatomic investigation. Two experienced orthopaedic surgeons performed the anatomic dissection using loupes (magnification ×3.5). Attention was focused on the anterolateral and lateral structures of the knee. After the skin and superficial fascia were removed, the iliotibial band was carefully separated from underlying structures. The anterolateral capsule was then examined under internal and external rotation and varus-valgus manual loading and at different knee flexion angles for the presence of any ligamentous structures. Eight additional unpaired, fetal lower limbs, gestational age 11 to 23 weeks, were used for histological analysis.

RESULTS

This study was not able to prove the presence of a distinct capsular or extracapsular ligamentous structure in the anterolateral capsular complex area. The presence of the fibular collateral ligament, a distal attachment of the biceps femoris, the entire lateral capsule, the iliotibial band, and the popliteus tendon in the anterolateral and lateral area of the knee was confirmed in all the samples. Histological analysis of the anterolateral capsule revealed a loose, hypocellular connective tissue with less organized collagen fibers compared with ligament and tendinous structures.

CONCLUSION

The main finding of this study was that the presence of a distinct ligamentous structure in the anterolateral complex is not supported from a developmental point of view, while all other anatomic structures were present.

CLINICAL RELEVANCE

The inability to prove the existence of a distinct ligamentous structure, called the anterolateral ligament, in the anterolateral knee capsule may indicate that the other components of the anterolateral complex, such as the lateral capsule, the iliotibial band, and its capsule-osseous layer, are more important for knee rotatory stability.

STUDY OF THE ANTEROLATERAL LIGAMENT OF THE KNEE IN FORMALIN-EMBEDDED CADAVERS

OBJECTIVE

To verify the incidence and characterize morphologically the anterolateral ligament of the knee (ALL) in cadaveric samples of the collection of the Laboratory of Anatomy of the Department of Morphology of the Universidade Federal do Espírito Santo.

METHODS

Dissections and cross sections were performed for mesoscopic analysis of the anterolateral region of 15 knees preserved in 4% formalin solution in order to identify the ALL.

RESULTS

After dissection of the skin and subcutaneous tissue of the knee anterolateral region, it was possible to identify the iliotibial tract (ITT), the patellar ligament and the femoral biceps tendon. The ITT was removed from the Gerdy tubercle and the following structures were visualized: knee joint capsule, fibular collateral ligament and popliteal tendon. However, the ALL was not identified in any of the samples.

CONCLUSIONS

The ALL could not be identified in any of the specimens studied, either through dissection or mesoscopic analysis. Level of Evidence III, Diagnosis Studies - Investigation of an Exam for Diagnosis.

Anatomic dissection of the anterolateral ligament (ALL) in paired fresh-frozen cadaveric knee joints

INTRODUCTION

Different dissection studies as well as comparative studies about the anterolateral ligament of the knee (ALL) already exist and the structure's topology and properties have been shown. However, most of the studies investigating the ligament were performed in embalmed knees, which is thought to change the structural integrity of ligaments and thus the topologic and dynamic measurements. Since the biomechanical function of the ALL is not fully understood until today and a correlation with the pivot shift phenomenon is yet speculative, further studies will have to clarify its definitive importance. Its function as a limiter of internal rotation and lateral meniscal extrusion leads to the assumption of a secondary knee stabilizer.

METHODS

Twenty paired fresh-frozen cadaveric knees of ten donors have been dissected in a layerwise fashion. After identification of the ALL, topologic measurements were undertaken using a digital caliper.

RESULTS

The ALL could be identified as a tender, pearly structure in front of the anterolateral joint capsule in only 60% of the dissected knee joints. Only 20% of donors had a bilateral ALL while 80% had an ALL only in one side. Mean length, thickness and width as well as topographic measurements were comparable to other available studies investigating fresh-frozen cadavers.

CONCLUSION

Anatomy and topography of the ALL seem to be highly variable, but consistent within certain borders. Prevalence has to be argued though as it strongly differs between studies. The impact of an ALL absence, even if only unilateral, needs to be investigated in clinical and imaging studies to finally clarify its importance.

Anterolateral Ligament of the Fetal Knee: An Anatomic and Histological Study

BACKGROUND

The anterolateral ligament (ALL) of the knee has recently been described in detail. Most studies of the ALL have been conducted in adults; therefore, little is known about the anatomy and histology of the ALL in younger patients, and nothing is known about the fetal presence of the ALL.

PURPOSE

To evaluate the ALL in human fetuses to determine its presence or absence and to describe its microscopic anatomy and histological features compared with the findings of studies conducted in adults.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twenty human fetal cadaveric specimens were used. The mean age of the fetuses was 28.64 ± 3.20 weeks. The ALL was dissected in the anterolateral region of the knee, and its anatomic parameters, including its origin, insertion, and path in relation to known adjacent anatomic landmarks, in addition to its length, width, and thickness over the path toward the tibia, were measured. After dissection, the ALL was removed en bloc with a portion of the lateral meniscus for histological analysis of 4-μm sections, hematoxylin and eosin staining, and immunohistochemical staining for type I collagen.

RESULTS

The ALL was located in all dissected knees. Its origin was located at a mean distance of 1.87 mm from the origin of the lateral collateral ligament, with variations from the center of the lateral epicondyle to posterior and proximal to it, and it exhibited an anterior-inferior path toward the tibia, an insertion in the lateral meniscus approximately 2.08 mm anterior to the popliteal tendon, and another insertion in the tibia between the Gerdy tubercle and the fibular head at 2.46 mm below the articular cartilage. The histological sections of the ALL showed well-organized, dense collagenous tissue fibers with elongated fibroblasts (mean, 1631 fibroblasts/mm²) and a predominance of type I collagen.

CONCLUSION

The ALL is present during fetal development, with anatomic and histological features similar to those of the adult ALL.

CLINICAL RELEVANCE

The findings of this study help to better understand the ALL's anatomy and histology from the fetal period to adulthood. The study presents the existence of the ALL since fetal development, emphasizes the characterization of the ALL, and brings important information to future pediatric ALL lesion studies.

Kinematic outcomes following ACL reconstruction

Anterior cruciate ligament (ACL) reconstruction aims to restore the translational and rotational motion to the knee joint that is lost after injury. However, despite technical advancements, clinical outcomes are less than ideal, particularly in return to previous activity level. A major issue is the inability to standardize treatment protocols due to variations in materials and approaches used to accomplish ACL reconstruction. These include surgical techniques such as the transtibial and anteromedial portal methods that are currently under use and the wide availability of graft types that will be used to reconstruct the ACL. In addition, concomitant soft tissue injuries to the menisci and capsule are frequently present after ACL injury and, if left unaddressed, can lead to persistent instability even after the ACL has been reconstructed. Advances in the field of biomechanics that help to objectively measure motion of the knee joint may provide more precise data than current subjective clinical measurements. These technologies include extra-articular motion capture systems that measure the movement of the tibia in relation to the femur. With data gathered from these devices, a threshold for satisfactory knee stability may be established in order to correctly identify a successful reconstruction following ACL injury.