The anterolateral ligament of the knee: A dissection study

The Anterolateral Ligament of the Knee Is a Nonisometric Thin Ligament With High Prevalence and Almost Constant Attachment to the Lateral Meniscus: A Systematic Review With Meta-analysis

PURPOSE

To provide comprehensive information about the anterolateral ligament (ALL) prevalence, morphometry, isometry, insertions, histology, and its relationship with the lateral meniscus (LM).

METHODS

The study was performed, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Eligible cadaveric studies investigating the frequency of the ALL presence, and anatomical features were identified through an online search of the PubMed, Scopus, and Cochrane Central databases from inception to June 2022. Statistical analysis was conducted with the open-source R programming language using the "meta" package. The Higgins I2 statistic was used for quantifying heterogeneity.

RESULTS

Thirty-three studies (1,478 cadaveric knees) were included. The ALL had a 79% prevalence. It was attached to the LM periphery in 97% of studies. Most studies reported a femoral insertion of the ALL, just proximal and posterior to the lateral epicondyle. Tibial attachment is constant at the midpoint between Gerdy's tubercle and fibular head. The mean ALL thickness at the joint line was 1.6 [1.2; 2.0] mm. The ALL length was found to significantly change across the knee flexion (P < .01). It was increased from 0° to 60° and decreased after 60° flexion. Seven histological studies demonstrated a typical ligamentous microstructure.

CONCLUSION

The ALL is a thin ligament, distinct to the knee capsule, which may be found in 79% of the knees having an almost constant attachment to the LM. The ALL is not isometric. It becomes tense during internal rotation and between 30° and 60° knee flexion. Pooled results should be interpreted with caution due to the high heterogeneity among the included studies.

CLINICAL RELEVANCE

This study sheds light on controversial issues and provides comprehensive and accurate information about the essential anatomical knowledge on ALL, which may contribute to optimizing ALL reconstruction surgical techniques and biomechanical settings.

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.

The effects of alteration in muscle activation on the iliotibial band during an exhaustive run

PURPOSE

Long exhausted running causes pain at the lateral femoral epicondyle for some runners. The pain has been revealed to be related to the behavior of the iliotibial band (ITB) during running. The purpose of this study is to examine the effects of in-series musculature on the behavior of the ITB in healthy participants during an exhaustive run.

METHODS

Twenty-five healthy participants (15 males, 10 females) were recruited in the current study. All participants performed a 30-minute exhaustive run at a self-selected speed with laboratory-provided footwear. Muscle activities of ITB-related muscles including tensor fascia latae (TFL), gluteus maximus (Gmax), gluteus medius (Gmed), biceps femoris (BF), and vastus lateralis (VL) were recorded using surface electromyography (EMG).

RESULTS

Maximum amplitudes at the initial stage (the first minute), the mid stage (the 15-minute), and the end stage (the 30-minute) were compared during the exhaustive running. Significant decreases (p < 0.05) were observed in the maximum amplitudes of the TFL, Gmax, Gmed, and BF at the mid (decreased by ~ 15%) and end (decreased by ~ 30%) stages compared to the initial stage. The onset and the offset remained unaltered during the running (p ≥ 0.05).

CONCLUSION

The behavior of the healthy ITB might be altered due to the activities of the in-series musculature. Excessive compression forces might be applied to the lateral femoral epicondyle from the ITB to provide stability for the knee joint during an exhaustive run. The findings could provide a basic understanding of the behavior of healthy ITB.

Sharing of proximal fibers by the anterolateral and lateral collateral ligaments in the human knee: a cadaveric study

Literature is highly inconsistent in describing the proximal attachment of the anterolateral ligament (ALL) and its relationship with the lateral collateral ligament (LCL) in human knees. This observational study aims to investigate that lacuna. The gross dissection was performed in the lower limbs (n = 83) from the donated adult-age (> 18 years) embalmed cadavers from medical institutions in the north and east India. The dissected knee specimens were first examined macroscopically. Further routine and special staining and microscopic examinations were performed. The ALL was absent in approximately 20.4% of the studied knee specimens (17/83). In remaining, the sharing of ALL and LCL proximal fibers was observed as a consistent finding (~ 97%) with rare exceptions. The mean length of the tibial and meniscal limbs of ALL was 1.57 ± 0.8 cm [Range (R) 0.5-4 cm] and 0.73 ± 0.47 cm [Range (R) 0.1-1.6 cm], respectively. In addition, multiple variations in its presentation were observed. We propose that the proximal sharing of LCL-ALL fibers is a dominant feature in the studied population. The sharing of the fibers may impact the biomechanics and injury mechanisms for both ligaments. The possibility of ethnic variations in the ALL morphology should be a concern during reconstruction surgery.

Anterolateral ligament of the knee-Cadaver study in a Caucasian population

INTRODUCTION

Despite the recognized importance of the anterolateral ligament (ALL) in rotational stability of the knee, some studies still deny its role and even its existence. We studied the prevalence of the ALL in a Caucasian population, as well as its characteristics and anatomical relationships.

MATERIALS AND METHODS

The study was performed on 20 knees from 10 embalmed cadavers. A lateral approach, as described by Steven Claes, was used and the relations of the ALL with the lateral epicondyle, lateral inferior genicular artery, lateral meniscus, Gerdy's tubercle and fibular head were recorded. Its length and its width were also measured.

RESULTS

The ALL was identified in 16 knees. Its origin was at a distance inferior to 1mm posterior and proximal to the lateral femoral epicondyle and insertion within a mean distance of 2.1±0.6mm from the tibial articular surface, 20.6±1.3mm from the Gerdy's tubercle and 20.3±1.2mm from the fibular head. In all cases ALL presented mutual fibers with the lateral meniscus. The length was 35.8±4.6mm and the width was 4.2±1.3/4.9±1.0/6.5±1.5mm at its proximal, middle and distal third, respectively. No difference was found between gender and the dimensions of the ligament.

CONCLUSIONS

The ALL was found in 80% of the knees. Its origin is closely related to the lateral collateral ligament and its insertion is halfway between the fibular head and the Gerdy's tubercle. In all cases, we verified the connection between ALL and the lateral meniscus.

Anterolateral ligament of the knee-Cadaver study in a Caucasian population

INTRODUCTION

Despite the recognized importance of the anterolateral ligament (ALL) in rotational stability of the knee, some studies still deny its role and even its existence. We studied the prevalence of the ALL in a Caucasian population, as well as its characteristics and anatomical relationships.

MATERIALS AND METHODS

The study was performed on 20 knees from 10 embalmed cadavers. A lateral approach, as described by Steven Claes, was used and the relations of the ALL with the lateral epicondyle, lateral inferior genicular artery, lateral meniscus, Gerdy's tubercle and fibular head were recorded. Its length and its width were also measured.

RESULTS

The ALL was identified in 16 knees. Its origin was at a distance inferior to 1mm posterior and proximal to the lateral femoral epicondyle and insertion within a mean distance of 2.1±0.6mm from de tibial articular surface, 20.6±1.3mm from the Gerdy's tubercle and 20.3±1.2mm from the fibular head. In all cases ALL presented mutual fibers with the lateral meniscus. The length was 35.8±4.6mm and the width was 4.2±1.3/4.9±1.0/6.5±1.5mm at its proximal, middle and distal third, respectively. No difference was found between gender and the dimensions of the ligament.

CONCLUSIONS

The ALL was found in 80% of the knees. Its origin is closely related to the lateral collateral ligament and its insertion is halfway between the fibular head and the Gerdy's tubercle. In all cases, we verified the connection between ALL and the lateral meniscus.

Function and strain of the anterolateral ligament part II: reconstruction

PURPOSE

Anterolateral rotatory instability (ALRI) may result from isolated ruptures of the anterior cruciate ligament (ACL) or combined lesions with the anterolateral ligament (ALL). Biomechanical studies have demonstrated that the ALL contributes to the overall rotational stability of the knee. The purpose of this study was to investigate the biomechanical function of anatomic ALL reconstruction (ALL_rec) in the setting of a combined ACL and ALL injury and reconstruction. The hypothesis was that combined ACL reconstruction (ACL_rec) and ALL_rec (ACL/ALL_rec) significantly reduces internal rotation and shows load sharing between both reconstructions compared with isolated ACL_rec.

METHODS

Eight fresh-frozen cadaveric knees were evaluated using a six degrees of freedom knee simulator. Continuous passive motion and external loads were tested. Kinematic differences between ACL_rec and combined ACL/ALL_rec were compared. Additionally, ACL graft tension and ALL graft strain were measured continuously throughout the testing protocol.

RESULTS

Combined anatomic ACL/ALL_rec significantly improved the internal rotatory stability compared with isolated ACL_rec at 30°-90° under an internal rotation moment. During a static pivot-shift test, additional ALL_rec showed no significant reduction of ap-translation. ALL_rec resulted in an increase in ACL graft tension during continuous passive motion and with additional internal rotation moment.

CONCLUSION

In the case of a combined ACL and ALL deficiency, concurrent ACL_rec and ALL_rec significantly improved the rotatory stability of the knee compared with solely reconstructing the ACL at flexion angles ≥ 30°. Nevertheless, additional ALL_rec with fixation at 60° and with low tension could not restore extension-near rotatory stability. For that reason, ALL_rec with fixation at 60° flexion cannot be recommended in clinical application.

The Association Between Bone Bruises and Concomitant Ligaments Injuries in Anterior Cruciate Ligament Injuries: A Systematic Review and Meta-analysis

Background

Bone bruises and concomitant ligament injuries after anterior cruciate ligament (ACL) injuries have attracted attention, but their correlation and potential clinical significance remain unclear.

Purpose

To assess the relationship between bone bruises and concomitant ligamentous injuries in ACL injuries.

Study design

Systematic review.

Methods

A comprehensive search of PubMed, Embase, Web of Science, and Cochrane Library was completed from inception to October 20, 2021. All articles that evaluated the relationship between bone bruises and related ligaments injuries were included. Methodological Index for Non-Randomized Studies (MINORS) was used for quality assessment as well as Review Manager 5.3 was used for data analysis.

Results

A total of 19 studies evaluating 3292 patients were included. After meta-analysis, anterolateral ligament (ALL) injuries were associated with bone bruising on the lateral tibial plateau (LTP) (RR = 2.33; 95% CI 1.44-3.77; p = 0.0006), lateral femoral condyle (LFC) (RR = 1.97; 95% CI 1.37-2.85; p = 0.0003) and medial tibial plateau (MTP) (RR = 1.62; 95% CI 1.24-2.11; p = 0.0004); Moreover, medial collateral ligament (MCL) injuries were associated with bone bruising on the femur (RR = 1.49; 95% CI 1.17-1.90; p = 0.001), and no statistical significance was found between bone bruising on the MTP and Kaplan fiber (KF) injuries (RR = 1.58; 95% CI 1.00-2.49; p = 0.05). Nonetheless, the current evidence did not conclude that bone bruises were associated with lateral collateral ligament (LCL) injuries.

Conclusion

For individuals with an ACL injury, bone bruises of the LTP, LFC, and MTP can assist in the diagnosis of ALL injuries. Furthermore, femoral bruising has potential diagnostic value for MCL injuries. Knowing these associations allows surgeons to be alert to ACL-related ligament injuries on MRI and during operations in future clinical practice.

Graft choices for anterolateral ligament knee reconstruction surgery: Current concepts

The anterolateral ligament (ALL) is a primary structure of the anterolateral complex of the knee that contributes to internal rotational stability of the joint. Injury of the ALL is commonly associated with rupture of the anterior cruciate ligament. If left untreated, ALL lesions may lead to residual anterolateral rotational instability of the knee after anterior cruciate ligament reconstruction, which is a common cause of anterior cruciate ligament graft failure. The function of the ALL can be restored by lateral extraarticular tenodesis or anterolateral ligament reconstruction (ALLR). In the lateral extraarticular tenodesis procedure, a strip of the iliotibial band is placed in a non-anatomical position to restrain the internal rotation of the tibia, while in ALLR, a free graft is fixed at the insertion points of the native ALL. Gracilis and semitendinosus grafts have mainly been utilized for ALLR, but other autografts have also been suggested. Furthermore, allografts and synthetic grafts have been applied to minimize donor-site morbidity and maximize the size and strength of the graft. Nevertheless, there has been no strong evidence to fully support one method over another thus far. The present review presents a detailed description of the graft choices for ALLR and the current literature available in regard to the effectiveness and outcomes of published surgical techniques.

Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction Using a Single Achilles Tendon Allograft: A Technical Note

Clinical outcomes after anterior cruciate ligament reconstruction (ACLR) have improved remarkably. However, residual rotational instability of the knee joint remains a major concern. The anterolateral ligament (ALL) has recently gained interest as a secondary stabilizer of knee joint rotatory instability, and this has led to the attempt of ALL reconstruction (ALLR) in combination with ACLR to restore rotational stability in patients with anterior cruciate ligament (ACL) injury. Although several techniques for ALLR have recently been introduced, the ideal graft type and surgical technique for combined ACLR and ALLR are yet to be established. This technical note therefore aimed at introducing a novel surgical procedure involving the use of a single Achilles tendon allograft as a relatively simple and minimally invasive procedure for combined ALL and ACL reconstruction.

Injuries to the anterolateral ligament are observed more frequently compared to lesions to the deep iliotibial tract (Kaplan fibers) in anterior cruciate ligamant deficient knees using magnetic resonance imaging

PURPOSE

To determine the accuracy of detection, injury rate and inter- and intrarater reproducibility in visualizing lesions to the anterolateral ligament (ALL) and the deep portion of the iliotibial tract (dITT) in anterior cruciate ligament (ACL) deficient knees.

METHODS

Ninety-one consecutive patients, out of those 25 children (age 14.3 ± 3.5 years), with diagnosed ACL tears were included. Two musculoskeletal radiologists retrospectively reviewed MRI data focusing on accuracy of detection and potential injuries to the ALL or dITT. Lesion were diagnosed in case of discontinued fibers in combination with intra- or peri-ligamentous edema and graded as intact, partial or complete tears. Cohen's Kappa and 95% confidence intervals (95% CI) were determined for inter- and intrarater reliability measures.

RESULTS

The ALL and dITT were visible in 52 (78.8%) and 56 (84.8%) of adult-and 25 (100%) and 19 (76.0%) of pediatric patients, respectively. The ALL was injured in 45 (58.5%; partial: 36.4%, compleate: 22.1%) patients. Partial and comleate tears, where visualized in 21 (40.4%) and 16 (30.8%) adult- and seven (28.0%) and one (4%) peditric patients. A total of 16 (21.3%; partial: 13.3%, compleate: 8.0%) dITT injuries were identified. Partal and complete lesions were seen in seven (12.5%) and five (8.9%) adult- and three (15.8%) and one (5.3%) pediatric patients. Combined injuries were visualized in nine (12.7%) patients. Inter-observer (0.91-0.95) and intra-observer (0.93-0.95) reproducibility was high.

CONCLUSION

In ACL injured knees, tears of the ALL are observed more frequently compared to lesions to the deep iliotibial tract. Combined injuries of both structures are rare. Clinically, the preoperative visualization of potentially injured structures of the anterolateral knee is crucial and is important for a more personalized preoperative planning and tailored anatomical reconstruction. The clinical implication of injuries to the anterolateral complex of the knee needs further investigation.

LEVEL OF EVIDENCE

II.

Prevalence and morphometric characteristics of the anterolateral ligament of the knee in a sample of Colombian human cadavers

Introduction: The anatomy of the knee and its ligaments is clearly described in the relevant literature; however, several studies have found new structures associated with this joint, such as the anterolateral ligament (ALL) of the knee. The prevalence of this ligament varies a lot around the world, and studies addressing this topic in Colombian population are scarce. Objective: To determine the prevalence of ALL and its morphometric characteristics in a sample of Colombian human cadavers. Materials and methods: Cross-sectional study in which the knee joints of 15 human cadavers were dissected and analyzed. In order to ensure the integrity of anatomical structures such as ligaments and tendons, specimens should have not undergone previous dissections, so only 29 knees were included for analysis. The presence of the ligament was verified, and the proximal and distal insertion site, as well as its length and width, were established through the dissection. Results: The prevalence of ALL was 24.13%, as it was identified in 7 of the 29 dissected knees (4 left and 3 right knees). The average length and width of the ALLs found were 37.5mm (range: 24-52.4mm) and 3.9mm (range: 2.6-6mm), respectively. Conclusions: This study allowed confirming the presence of the ALL in Colombian population, although with a lower prevalence than that described in countries such as France, India, China, USA and Brazil. In turn, its morphometric characteristics were similar to those reported worldwide, since the average length and width found here are consistent with those described in the literature.

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.

Microstructural and Mechanical Properties of the Anterolateral Ligament of the Knee

BACKGROUND

The variable anatomy and controversy of the anterolateral ligament (ALL) reflect the complex relationship among the anterolateral knee structures.

PURPOSE/HYPOTHESIS

The purpose was to quantify the microstructural and mechanical properties of the ALL as compared with the anterolateral capsule (ALC) and lateral collateral ligament (LCL). The primary hypotheses were that (1) there is no difference in these properties between the ALL and ALC and (2) the LCL has significantly different properties from the ALL and ALC.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The LCL, ALL, and ALC were harvested from 25 cadaveric knees. Mechanical testing and microstructural analyses were performed using quantitative polarized light imaging. The average degree of linear polarization (AVG DoLP; mean strength of collagen alignment) and standard deviation of the angle of polarization (STD AoP; degree of variation in collagen angle orientation) were calculated.

RESULTS

Linear region moduli were not different between the ALC and ALL (3.75 vs 3.66 MPa, respectively; P > .99). AVG DoLP values were not different between the ALC and ALL in the linear region (0.10 vs 0.10; P > .99). Similarly, STD AoP values were not different between the ALC and ALL (24.2 vs 21.7; P > .99). The LCL had larger modulus, larger AVG DoLP, and smaller STD AoP values than the ALL and ALC. Of 25 knee specimens, 3 were observed to have a distinct ALL, which exhibited larger modulus, larger AVG DoLP, and smaller STD AoP values as compared with nondistinct ALL samples.

CONCLUSION

There were no differences in the mechanical and microstructural properties between the ALL and ALC. The ALC and ALL exhibited comparably weak and disperse collagen alignment. However, when a distinct ALL was present, the properties were suggestive of a ligamentous structure.

CLINICAL RELEVANCE

The properties of the ALL are similar to those of a ligament only when a distinct ALL is present, but otherwise, for the majority of specimens, ALL properties are closer to those of the capsule. Variability in the ligamentous structure of the ALL suggests that it may be more important in some patients than others and reconstruction may be considered in selective patients. Further study is needed to better understand its selective role and optimal indications for reconstruction.

Editorial Commentary: Another Take on the Anterolateral Ligament: High-Grade Are Worse Than Low-Grade Injuries, But the Categorization Is Problematic

The anatomy, function, and existence of the anterolateral ligament (ALL) is still hotly debated and a controversial topic. Currently both basic biomechanical and clinical studies are not providing sufficient and strong evidence to either support or refute that the ALL plays an important role for knee stability. One could argue that stability is provided by the anterolateral complex, including the iliotibial band, Kaplan fibers, and the anterolateral capsule, which may contain a structure called the ALL. Magnetic resonance imaging (MRI) is routinely performed in patients with anterior cruciate ligament (ACL) injury, but unfortunately ALL injuries cannot be reliably diagnosed in patients with concomitant ACL tears. When dividing ALL injuries into high and low grade using preoperative MRI and investigating clinical outcomes after double-bundle ACL reconstruction, patients with high-grade injuries have inferior outcomes and a significantly greater revision rates. However, the limitations of this research reduce the validity of these conclusions: high rate of loss to follow-up above accepted standard, unequal size of their study groups, fragility index of zero, the inaccuracy of diagnosing ALL injuries in the presence of ACL tears on MRI, and the dilemma with randomly classifying high- and low-grade ALL injury based on MRI.

Knee laxity in anterolateral complex injuries versus medial meniscus posterior horn injuries in anterior cruciate ligament injured knees: A cadaveric study

INTRODUCTION

There is considerable debate regarding the function of anterolateral knee structures, including the anterolateral ligament (ALL) and anterolateral capsule, as knee stabilizers in anterior cruciate ligament (ACL) injured knees. Medial meniscus posterior horn (MMPH) injuries have also been associated with increased knee laxity in ACL injured knees. The purpose of this cadaveric biomechanical study was to compare the effects of the anterolateral complex (ALC) injury and meniscectomy of MMPH on knee laxity in ACL injured knees.

HYPOTHESIS

ALC injury would have a greater effect on internal rotational laxity in ACL-injured knee than meniscectomy of MMPH.

MATERIAL AND METHODS

Matched-pair 10 fresh-frozen cadaveric knees underwent biomechanical evaluation of knee laxity. After testing the intact knee and ACL sectioned knee (ACL-) in matched-pair 10 fresh-frozen cadaveric knees, two groups were established: an ALC sectioning (ACL-/ALC-) group (n=5) and a MMPH meniscectomy (ACL-/MMPH-) group (n=5). Knee laxity was measured in terms of internal-external rotation, anterior-posterior translation, and varus-valgus angulation for each condition at knee flexion angles of 0°, 30°, 60° and 90°.

RESULTS

After the additional sectioning of the ALC (ACL-/ALC-), the mean internal rotation at 0°, 30°, 60° and 90° of knee flexion showed the greater internal rotation laxity compared than intact knee (p=0.020, 0.011, 0.005 and<0.001). It also significantly increased anterior translation from ACL- at 30° and 60° (p=0.011 and 0.005). In contrast, additional meniscectomy of the MMPH (ACL-/MMPH-) significantly increased external rotation laxity compared to intact knee (p=0.021, 0.018 and 0.024) and ACL- (p=0.037, 0.011 and 0.025) at 30°, 60° and 90°. ACL-/MMPH- also resulted in significantly increased anterior translation from ACL- at 30°, 60° and 90° (p=0.004, 0.008 and 0.002).

DISCUSSION

In conclusion, the anterolateral complex, which include the ALL and anterolateral capsule, may play an important role in stabilizing the knee against internal rotation and anterior translation, while the MMPH may contribute to resisting external rotation and anterior translation stability in ACL-injured knee.

LEVEL OF EVIDENCE

II, controlled laboratory study.

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?

MRI visibility of the anterolateral ligament and the deep structures of the iliotibial tract

Purpose

The visualization of potentially injured anatomical structures is crucial. Lately the anterolateral ligament (ALL) and the deep structures of the iliotibial tract (ITT) have been of increased clinical interest because of their role as important lateral stabilizers of the knee. The aim of this study was to assess the visibility of the ALL and the deep structures of the ITT using MRI. Good intra- and inter-observer reproducibility was hypothesized.

Methods

Knee MRI data from patients without ligamentous lesions were retrospectively analyzed by two radiologists at two time points using axial and coronal sequences. The visibility of the different parts of the ALL (femoral, meniscal and tibial part) and of the deep ITT, namely the deep attachments of the ITT to the distal femur and capsulo-osseous layer of the ITT, were determined on a binary (yes/no) basis.

Results

Seventy-one cases (42 men, 29 women) were studied. Inter-observer agreement was high. Cohen’s kappa was 0.97 for the tibial part of the ALL and 0.76 for the femoral part. For the deep attachments of the ITT to the distal femur Cohen’s kappa was 0.94. For each of the investigated parameters absolute agreement between the observers was at least 88%. Regarding intra-observer agreement Cohen’s kappa was 0.62 for the femoral part of the ALL and 0.85 for the tibial part of the ALL. For the deep attachments of the ITT to the distal femur Cohen’s kappa was 0.94. For each investigated parameter absolute agreement between the two time points was at least 83%.

Conclusions

The presence of the anterolateral structures of the knee can be determined with substantial inter- and intra-observer agreement using MRI examination. This is applicable for both the ALL and the deep ITT.

Level of evidence

Diagnostic study – Level III.

Anterior Cruciate Ligament Injury and the Anterolateral Complex of the Knee-Importance in Rotatory Knee Instability?

PURPOSE OF REVIEW

In the setting of rotatory knee instability following anterior cruciate ligament (ACL) reconstruction, there has been a resurgence of interest in knee's anterolateral complex (ALC). Reconstruction or augmentation of the ALC with procedures such as a lateral extra-articular tenodesis (LET) has been proposed to reduce rotatory knee instability in conjunction with ACL reconstruction. The current review investigates the recent literature surrounding the role of the ALC in preventing rotatory knee instability.

RECENT FINDINGS

The knee's anterolateral complex (ALC) is a complex structure composed of the superficial and deep portions of the iliotibial band, the capsulo-osseous layer, and the anterolateral capsule. Distally, these various layers merge to form a single functional unit which imparts stability to the lateral knee. While the iliotibial band and the capsule-osseous layer have been shown to be primary restraints to rotatory motion after ACL injury, the biomechanical role of the anterolateral capsule remains unclear. Biomechanical studies have shown that the anterolateral capsule and the anterolateral thickening of this capsule act as a sheet of fibrous tissue which does not resist motion around the knee as other longitudinally oriented ligaments do. Augmentation of the ALC, with LET, has been performed globally for over 30 years. This procedure can decrease rotatory knee instability, but long-term studies have found little difference in patient-reported outcomes, osteoarthritis, or ACL reconstruction failure with the addition of LET. Further research is needed to clarify indications for the clinical use of ALC-based procedures.

The anterolateral ligament of the knee joint: a review of the anatomy, biomechanics, and anterolateral ligament surgery

Residual knee instability and low rates of return to previous sport are major concerns after anterior cruciate ligament (ACL) reconstruction. To improve outcomes, surgical methods, such as the anatomical single-bundle technique or the double-bundle technique, were developed. However, these reconstruction techniques failed to adequately overcome these problems, and, therefore, new potential answers continue to be of great interest. Based on recent anatomical and biomechanical studies emphasizing the role of the anterolateral ligament (ALL) in rotational stability, novel surgical methods including ALL reconstruction and anterolateral tenodesis have been introduced with the possibility of resolving residual instability after ACL reconstruction. However, there is still little consensus on many aspects of the ALL, including: several anatomical issues, appropriate indications for ALL surgery, and the optimal surgical method and graft choice for reconstruction surgery. Therefore, further studies are necessary to advance our knowledge of the ALL and its contribution to knee stability.

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.

Correlation Analysis of the Anterolateral Ligament Length with the Anterior Cruciate Ligament Length and Patient's Height: An Anatomical Study

The aim of this study was to evaluate the anatomical characteristics of the anterolateral ligament of the knee (ALL) with the focus on potential gender differences. The ALL length and the length of the lateral collateral ligament (LCL) were taken in extension. The length of the anterior cruciate ligament (ACL) was measured at 120° flexion. We correlated the length of the ALL with the LCL and ACL with respect to potential gender differences. The ALL was significantly (p = 0.044) shorter in females (mean length: 32.8 mm) compared to males (mean length: 35.7 mm). The length of the ALL correlated significantly positively with the lengths of the ACL (p < 0.001) and the LCL (p < 0.001). There was no significant correlation with the total leg length (TLL) (p = 0.888) and body size (p = 0.046). Furthermore, TLL and donor size correlated significantly positively (p < 0.001). The ALL length correlated significantly positively with the ACL and the LCL length. The ALL length did neither correlate with the TLL nor the donor size. This fact may contribute to planning of graft harvesting in the upcoming techniques for ALL reconstruction.

Elongation Patterns of the Anterior and Posterior Borders of the Anterolateral Ligament of the Knee

PURPOSE

To compare the elongation patterns of the anterior and posterior borders of the anterolateral ligament (ALL) at varying knee flexion angles with the knee in a neutral position without any external forces and with external forces applied, including anterior-posterior translation, internal-external rotation, and varus-valgus angulation.

METHODS

Eight cadaveric knees were tested in a custom knee testing system. Elongation of the anterior and posterior borders of the ALL was measured using a MicroScribe 3DLX system at knee flexion angles of 0°, 30°, 60°, and 90° and after the application of internal-external rotation, anterior-posterior translation, and varus-valgus angulation.

RESULTS

The anterior border showed a slight noncontinuous increase in percentage elongation (0.8% ± 2.2%) whereas the posterior border showed a continuous decrease in percentage elongation (-12.0% ± 2.8%) as knee flexion increased (P < .001). Apart from the elongation of the posterior border at 90° of knee flexion, internal rotation, varus angulation, and anterior translation resulted in a significant increase in the percentage elongation of the anterior and posterior borders at each flexion angle compared with external rotation, valgus angulation, and posterior translation, respectively.

CONCLUSIONS

The ALL shows different elongation patterns between the anterior and posterior borders, with a continuous decrease in the percentage elongation of the posterior border as knee flexion increases.

CLINICAL RELEVANCE

This study presents useful evidence to resolve the uncertainty regarding the change in length of the ALL at various degrees of knee flexion. This information may be helpful for deciding the optimal knee flexion angle during ALL graft fixation. The findings from this study suggest that graft fixation during ALL reconstructions should be performed at close to full extension of the knee.

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.

Anatomical Consideration of the Anterolateral Ligament of the Knee

Many researchers have studied the structures of the anterolateral part of the knee. Several researchers have investigated the existence of the anterolateral ligament (ALL) and its frequency has been inconsistently reported. Therefore, we assessed whether the ALL is the anatomical true ligament and studied the morphological variations of this structure. Sixty-four Korean adult cadavers (120 knees, mean age: 79.1 years) were used for this study. The lateral part of the knee joint was carefully dissected with internal rotation of the tibia. We checked the existence and morphological features and measured the dimensions (length, width, and thickness) of the ALL. The ALL was clearly distinguished from the capsulo-osseous layer of the iliotibial tract and runs obliquely from the lateral femoral epicondyle to the tibial plateau. The ALL was found in 42.5% of the samples, and 15 cadavers had ALLs in both knees. There was no prevalence difference between females and males. Most of the anterior border of the ALL was blended with the knee capsule. Therefore, we concluded that this structure is a local thickening of the capsule in the anterolateral region of the knee, where it possibly developed against some external physical stress. Therefore, the ALLs in this present study can be defined as a capsular ligament of the knee and, as per the nomenclature of the capsular ligament, can be also called the ‘anterolateral (capsular) ligament'.

Proximal fixation anterior to the lateral femoral epicondyle optimizes isometry in anterolateral ligament reconstruction

PURPOSE

Concomitant anterolateral ligament (ALL) injury is often observed in patients with an anterior cruciate ligament injury leading some to recommend concurrent ALL reconstruction. In ligament reconstruction, it is imperative to restore desirable ligament length changes to prevent stress on the graft. The purpose of this investigation is to identify the optimal femoral and tibial locations for fixation in ALL reconstruction.

METHODS

3D computerized tomography (CT) knee models were obtained from six fresh-frozen, unpaired, cadaveric human knees at 0°, 10°, 20°, 30°, 40°, 90°, 110°, and 125°of knee flexion. Planar grids were projected onto the lateral knee. Isometry between each tibial and femoral grid point was calculated at each angle of flexion by the length change in reference to the length at 0° of knee flexion. The mean normalized length change over the range of motion was calculated for each combination of points at all angles of flexion were calculated.

RESULTS

Fixation of the ALL to the lateral femoral epicondyle or 5 mm anterior to the epicondyle with tibial fixation on the posteroinferior aspect of the tibial condyle (14-21 mm posterior to Gerdy's tubercle and 13-20 mm below the joint line) provided the lowest average length change for all possible ALL tibial insertion points. Minimal length change for all femoral fixation locations occurred from 20° to 40° of flexion, which identifies the angle of flexion where graft tensioning should occur intraoperatively.

CONCLUSION

With the use of 3D reconstructed models of knee-CT scans, we observed that there was no ALL fixation point that was truly isometric throughout range of motion. Fixation of the anterolateral ligament on the lateral femoral epicondyle or anterior to the lateral femoral epicondyle and on the inferoposterior aspect of the tibial condyle restores isometry. Additionally, minimal length change was observed between 20° and 40° of flexion, which is the most appropriate range of knee flexion to tension the graft. Reproducing isometry reduces stress on the graft, which minimizes the risk of graft failure.

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.

The anterolateral ligament and the deep structures of the iliotibial tract: MRI visibility in the paediatric patient

PURPOSE

To assess the visibility of both the anterolateral ligament (ALL) and the deep structures of the iliotibial tract (ITT) by means of MRI in paediatric patients. To determine reproducibility for such measurements.

METHODS

Knee MRI data from patients aged <18a without lesions of the capsule or ligaments, fractures, bone edemas, foreign material or motion artifacts were analyzed by two musculoskeletal radiologists separately and twice. The visibility of the different parts of the ALL was determined (femoral, meniscal, tibial parts). Similarly, the visibility of the different parts of the deep ITT was determined: deep attachments of the ITT to the distal femur (insertion near septum, supracondylar insertion and retrograde insertion) and capsulo-osseous layer of the ITT.

RESULTS

We studied 61 cases (36 female, 25 male). Age was 15 years (±2.3). Interobserver agreement was high. Cohen's Kappa was 0.864 (95%CI: 0.715-1.000) for the tibial part of the ALL and 1.0 for the femoral part of the ALL. For the deep attachments of the ITT to the distal femur Kappa was 0.828 (95%CI: 0.685-0.971). Regarding intraobserver agreement, Cohen's Kappa was 1.0 for the femoral part of the ALL and 0.955 (95%CI: 0.867-1.000) for the tibial part of the ALL. For the deep attachments of the ITT to the distal femur Cohen's Kappa was 0.896 (95%CI: 0.782-1.000).

CONCLUSION

On the basis of our findings it is concluded that the presence of the anterolateral structures of the knee can be determined by MRI in a pediatric population with substantial inter- and intraobserver agreement. This is true for both the ALL and the deep structures of the ITT.

LEVEL OF EVIDENCE

Diagnostic study - Level 3.

Determining the change in length of the anterolateral ligament during knee motion: A three-dimensional optoelectronic analysis

BACKGROUND

The variation of the anterolateral ligament (ALL) length during knee motion is still unclear, and the knee position in which a reconstruction graft should be tensioned remains controversial. The objective of this study was to determine the variation of the ALL length during knee motion using a three-dimensional optoelectronic system.

METHODS

Kinematic analyses of 20 cadaveric knees were performed using a Motion Analysis® system. The variability of the measurements made during the five acquisition cycles was studied. Reliability was evaluated by two separate measurement sessions, with complete system reinstallation, using different cadavers and a new operator. The ALL length was analysed from extension to full flexion in three rotational conditions.

FINDINGS

When analysing the reliability of the five cycles, 82% of the measurements we found to have an Intra Class Correlation (ICC) >0.85. The reproducibility of inter-sessional measures by different operators and different cadavers was either good (ICC >0.75) or excellent (ICC >0.85). The ALL length was maximum in full internal rotation with the knee at 25° of flexion.

INTERPRETATION

This three-dimensional optoelectronic protocol allowed us to analyse the variation of the ALL length during intact knee motion with good reliability and the required accuracy to analyse this variable. The maximal length and highest tension of the ALL was reported at 25° of knee flexion in internal rotation, suggesting this as the optimal position for the knee joint when tensioning an ALL reconstruction.

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.

Anterolateral Ligament Repair With Suture Tape Augmentation

Recent insights into the structure and function of the anterolateral ligament (ALL) of the knee has resulted in a recognition of its contribution in rotational control of the knee. Several ALL reconstruction techniques have been described in the literature. This article describes, with video illustration, a percutaneous repair technique using suture tape augmentation. A tendon graft is not needed. This technique allows early mobilization and encourages natural healing of the ligament by protecting the ligament during the healing phase as a secondary stabilizer.

The Anterolateral Ligament of the Knee: A Proposed Classification System

The anterolateral ligament (ALL) is a potential stabilizer of the knee and cooperates with the anterior cruciate ligament (ACL). It originates on the lateral epicondyle of the femur, to which it is mainly posterior and proximal; insertion is posterior to Gerdy's tubercle. Its anatomical characteristics vary. Recent publications have focused on morphological variations concerning mainly the femoral and tibial attachments, and on morphometric measurements. Histological and cystochemical examinations have also been performed. Classical anatomical dissection was performed on 111 lower limbs (25 isolated and 86 paired) fixed in 10% formalin. The knee region was dissected using traditional techniques and the morphological features of the ALL were assessed: morphometric measurements and the types of ALL. The ALL was present in 70 individuals (37 woman and 33 men). In 30 cases, it was absent symmetrically, and in 11, it was present on just one side (P = 0.0011). The ALL was morphologically very variable. In type I (the most common form - 64.3%), a single band traveled parallel to the fibular collateral ligament (FCL); in type II the band crossed it. In type III, the origin was located on the lateral epicondyle of the femur and also on the lateral-posterior surface of the joint capsule, and the insertion was in the deep fascia of the leg: this type could be called a capsule. Type IV was characterized by a double ALL, type IIb by ligaments that bifurcated, and type V by the ALL starting directly from the FCL rather than the femoral epicondyle. The ALL is characterized by high morphological variability, both in its femoral and in its tibial attachments and in its course. Clin. Anat. 31:966-973, 2018. © 2018 Wiley Periodicals, Inc.

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.

Three-dimensional Magnetic Resonance Imaging of the Anterolateral Ligament of the Knee: An Evaluation of Intact and Anterior Cruciate Ligament-Deficient Knees From the Scientific Anterior Cruciate Ligament Network International (SANTI) Study Group

PURPOSE

To determine the visualization rate of the anterolateral ligament (ALL) in uninjured and anterior cruciate ligament (ACL)-deficient knees using 3-dimensional (3D) magnetic resonance imaging (MRI) and to characterize the spectrum of ALL injury observed in ACL-deficient knees, as well as determine the interobserver and intraobserver reliability of a 3D MRI classification of ALL injury.

METHODS

A total of 100 knees (60 ACL deficient and 40 uninjured) underwent 3D MRI. The ALL was evaluated by 2 blinded orthopaedic surgeons. The ALL was classified as follows: type A, continuous, clearly defined low-signal band; type B, warping, thinning, or iso-signal changes; and type C, without clear continuity. The comparison between imaging performed early after ACL injury (<1 month) and delayed imaging (>1 month) was evaluated, as was intraobserver and interobserver reliability.

RESULTS

Complete visualization of the ALL was achieved in all uninjured knees. In the ACL-deficient group, 24 knees underwent early imaging, with 87.5% showing evidence of ALL injury (3 normal, or type A, knees [12.5%], 18 type B [75.0%], and 3 type C [12.5%]). The remaining 36 knees underwent delayed imaging, with 55.6% showing evidence of injury (16 type A [44.4%], 18 type B [50.0%], and 2 type C [5.6%]). The difference in the rate of injury between the 2 groups was significant (P = .03). Multivariate analysis showed that the delay from ACL injury to MRI was the only factor (negatively) associated with the rate of injury to the ALL. Interobserver reliability and intraobserver reliability of the classification of ALL type were good (κ = 0.86 and κ = 0.93, respectively).

CONCLUSIONS

Three-dimensional MRI allows full visualization of the ALL in all normal knees. The rate of injury to the ALL in acutely ACL-injured knees identified on 3D MRI is higher than previous reports using standard MRI techniques. This rate is significantly higher than the rate of injury to the ALL identified on delayed imaging of ACL-injured knees.

LEVEL OF EVIDENCE

Level IV, diagnostic, case-control study.

The anterolateral ligament is a distinct ligamentous structure: A histological explanation

BACKGROUND

The aim was to determine whether the anterolateral ligament (ALL) had a histological structure that defined it as a real ligament.

METHODS

Histological examination of 30 ALL samples taken from fresh-frozen knees were performed. The ALL femoral insertion and its relationship with the lateral collateral ligament (LCL) were studied and the tibial insertion and its relationship with articular cartilage of the tibial joint surface were analyzed. For the ligamentous part, its histological structure and its differences with the articular capsule were studied.

RESULTS

This connective tissue is composed of a dense fibrous core constituted by a network of oriented collagenous fibers. The periphery of this dense connective center is made up of loose fibrocollagenous tissue with vascular structures and focal deposits of adipose tissue. This part was in contact but different to the joint capsule. With a perpendicular orientation of the collagen fibers relative to the bone, a fibrocartilaginous zone with an unmineralized hyalinized aspect, a mineralization front, its bone insertions presented a typical ligamentous insertion. With a cleavage plane between ALL and LCL femoral insertion, the ALL appeared to have a femoral insertion distinct from the LCL. ALL tibial insertion was less characteristic with less organized connective tissue and was at a distance from the articular cartilage.

CONCLUSION

From its bony insertion to its tissue composition and organization, the ALL has all the histological characteristics of a ligamentous structure. Our study confirms that ALL can be considered a real and distinct ligament.

Anterolateral Ligament of the Knee: Anatomy, Function, Imaging, and Treatment

The anterolateral ligament (ALL) of the knee has gained attention recently for its potential role in rotational stability of the knee, especially in association with anterior cruciate ligament (ACL) injuries. Anatomic studies have characterized the ALL as it runs in an anteroinferior and oblique direction from the lateral distal femur to the anterolateral proximal tibia, although the prevalence and variance of this ligament are not well understood. Magnetic resonance imaging and ultrasound have identified the ligament and linked it with the classically described Segond fracture. While the ALL likely plays a role in rotational stability of the knee, further studies investigating the significance of ALL injuries and the role of ALL reconstruction in combination with ACL reconstruction are warranted.

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.

[Anatomical study on anterolateral ligament in a Chinese population]

Objective

To make further exploration of the structure characteristics of anterolateral ligament (ALL) and provide clinical reference for diagnosis and treatment of ALL injury, especially for ALL reconstruction through anatomical study of ALL in a Chinese population.

Methods

Sixteen cadaveric knees, including 8 left knees and 8 right knees with sex ratio of 1∶1 and a mean age of 73.5 years (range, 57-84 years), were dissected to reveal the ALL through a standard approach. A qualitative and a quantitative characterizations of the ALL were performed.

Results

ALL was seen in 75.0% of the specimens, originating on the lateral femoral epicondyle, proximal and posterior to the lateral collateral ligament (LCL). It coursed on LCL or was parallel to LCL, anterodistally to its anterolateral tibial attachment approximately midway between the center of the Gerdy's tubercle and the lateral margin of the fibular head. A strong connection was observed between the middle part of the ALL and the periphery of the meniscal body of the lateral meniscus. The distance between the center of the insertion and Gerdy's tubercle was (23.9±3.3) mm; and the distance between the center of the insertion and the lateral margin of the fibular head was (23.8±4.0) mm. The ALL length at 0° and 60° flexion and neutral knee rotation were (44.8±5.1) mm and (47.8±5.5) mm respectively ( t=14.071, P=0.000), and the ligament had its great extend at 60° of knee flexion and internal rotation. Furthermore, the ALL length at 0° and 60° flexion of males were both significantly higher than those of females ( t=2.920, P=0.015; t=2.806, P=0.019), while other measurements differences were significant between males and females ( P>0.05).

Conclusion

ALL is an independent and a non-isometric ligament located in the anterolateral area to the knee, of which the length is different between males and females. ALL plays a role in rotational stability of the knee, and should be put much emphasis in clinical practice.

The Anterolateral Complex of the Knee

Background:

Significant controversy exists regarding the anterolateral structures of the knee.

Purpose:

To determine the layer-by-layer anatomic structure of the anterolateral complex of the knee.

Study Design:

Descriptive laboratory study.

Methods:

Twenty fresh-frozen cadaveric knees (age range, 38-56 years) underwent a layer-by-layer dissection to systematically expose and identify the various structures of the anterolateral complex. Quantitative measurements were performed, and each layer was documented with high-resolution digital imaging.

Results:

The anterolateral complex of the knee consisted of different distinct layers, with the superficial and deep iliotibial band (ITB) representing layer 1. The superficial ITB had a distinct connection to the distal femoral metaphysis and femoral condyle (Kaplan fibers), and the deep layers of the ITB were identified originating at the level of the Kaplan fibers proximally. This functional unit, consisting of the superficial and deep ITB, was reinforced by the capsulo-osseous layer of the ITB, which was continuous with the fascia of the lateral gastrocnemius and biceps femoris muscles. These 3 components of the ITB became confluent distally, and the insertion spanned from the Gerdy tubercle anteriorly to the lateral tibia posteriorly on a small tubercle (lateral tibial tuberosity). Layer 3 consisted of the anterolateral capsule, in which 35% (7/20) of specimens had a discreet mid-third capsular ligament.

Conclusion:

The anterolateral complex consists of the superficial and deep ITB, the capsulo-osseous layer of the ITB, and the anterolateral capsule. The anterolateral complex is defined by the part of the ITB between the Kaplan fibers proximally and its tibial insertion, which forms a functional unit. A discrete anterolateral ligament was not observed; however, the anterolateral ligament described in recent studies likely refers to the capsulo-osseous layer or the mid-third capsular ligament.

Clinical Relevance:

The anterolateral knee structures form a complex functional unit. Surgeons should use caution when attempting to restore this intricate structure with extra-articular procedures designed to re-create a single discreet ligament.

The anterolateral ligament: Anatomic implications for its reconstruction

BACKGROUND

The purpose of this study was to define the best anatomic parameters with which to perform an accurate anterolateral ligament (ALL) reconstruction. These parameters were anatomical insertions, allowing favorable isometry, length variation during flexion, and anthropometric predictors of ALL lengths.

METHODS

A total of 84 fresh-frozen cadaver knees were dissected to analyze the ALL, focusing on its femoral insertion. The ALL length was measured in different degrees of flexion (extension, 30°, 60°, and 90° of flexion) and rotation (neutral, internal or external rotation). The ALL width and thickness were measured. A correlation between ALL length, the general knee size and individual characteristics was investigated.

RESULTS

The ALL was present in 80 specimens (95%). The femoral footprint was always posterior (5.52±0.93 mm, range 3.83-6.94) and slightly proximal (1.51±0.75mm, range 0.63-2.37) to the lateral femoral epicondyle. The mean ALL length increased with internal rotation and decreased with external rotation (P<0.05). The maximum ALL length was found at 30° of flexion, and the minimum at 90°. There was a significant correlation between the ALL length and height, sex, and proximal femur dimensions.

CONCLUSION

In order to get an anatomical reconstruction with favorable isometry, it is recommended that the ALL femoral graft is implanted posterior and slightly proximal to the epicondyle. It is also suggested that the tension be adjusted by fixing the graft between 0 and 30° of flexion, being tighter near extension. This will allow good rotational stability without implying any stiffness.

The Segond Fracture Is an Avulsion of the Anterolateral Complex

BACKGROUND

The Segond fracture was classically described as an avulsion fracture of the anterolateral capsule of the knee. Recently, some authors have attributed its pathogenesis to the "anterolateral ligament" (ALL). Biomechanical studies that have attempted to reproduce this fracture in vitro have reported conflicting findings.

PURPOSE

To determine the anatomic characteristics of the Segond fracture on plain radiographs and magnetic resonance imaging (MRI), to compare this location with the location of the ALL described in prior radiographic and anatomic publications, and to determine the fracture's attachments to the soft tissue anterolateral structures of the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 36 anterior cruciate ligament-injured patients with Segond fractures (33 male, 3 female; mean age, 23.2 ± 8.4 years) were enrolled. MRI scans were reviewed to determine the anatomic characteristics of the Segond fracture, including the following: proximal-distal (PD) length, anterior-posterior (AP) width, medial-lateral (ML) width, PD distance to the lateral tibial plateau, AP distance to the Gerdy tubercle (GT), and AP distance from the GT to the posterior aspect of the fibular head. The attachment of the anterolateral structures to the Segond fragment was then categorized as the iliotibial band (ITB) or anterolateral capsule. Interrater reliability of the measurements was determined by calculating the Spearman rank correlation coefficient. MEDLINE, Web of Science, and the Cochrane Library were searched from inception to May 2016 for the following keywords: (1) "Segond fracture," (2) "anterolateral ligament," (3) "knee avulsion," (4) "lateral tibia avulsion," and (5) "tibial plateau avulsion." All studies describing the anatomic location of the Segond fracture and the ALL were included in the systematic review.

RESULTS

On plain radiographs, the mean distance of the midpoint of the fracture to the lateral tibial plateau was 4.6 ± 2.2 mm. The avulsed fracture had a mean PD length of 9.2 ± 2.5 mm and a mean ML width of 2.4 ± 1.4 mm. On MRI, the mean distance of the proximal fracture to the tibial plateau was 3.4 ± 1.6 mm. The mean PD length was 8.7 ± 2.2 mm, while the mean AP width was 11.1 ± 2.2 mm. The mean distance between the GT and the center of the fracture was 26.9 ± 3.3 mm, while the mean distance between the GT and the posterior fibular head was 53.9 ± 4.4 mm. The mean distance of the midpoint of the fracture to the tibial plateau was 7.8 ± 2.7 mm, while the center of the fracture was 49.9% of the distance between the GT and the posterior aspect of the fibular head. Analysis of soft tissue structures attached to the fragment revealed that the ITB attached in 34 of 36 patients and the capsule attached in 34 of 36 patients. One patient had only the capsule attached, another had only the ITB attached, and the last showed neither clearly attached. A literature review of 20 included studies revealed no difference between the previously described Segond fracture location and the tibial insertion of the ALL.

CONCLUSION

The results of this study confirmed that while the Segond fracture occurs at the location of the tibial insertion of the ALL, as reported in the literature, MRI was unable to identify any distinct ligamentous attachment. MRI analysis revealed that soft tissue attachments to the Segond fracture were the posterior fibers of the ITB and the lateral capsule in 94% of patients.

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.

The anterolateral complex of the knee: a pictorial essay

Injuries to the anterolateral complex of the knee can result in increased rotatory knee instability. However, to diagnose and treat patients with persistent instability properly, surgeons need to understand the multifactorial genesis as well as the complex anatomy of the anterolateral aspect of the knee in its entirety. While recent research focused primarily on one structure (anterolateral ligament-ALL), the purpose of this pictorial essay is to provide a detailed layer-by-layer description of the anterolateral complex of the knee, consisting of the iliotibial band with its superficial, middle, deep, and capsulo-osseous layer as well as the anterolateral joint capsule. This may help surgeons to not only understand the anatomy of this particular part of the knee, but may also provide guidance when performing extra-articular procedures in patients with rotatory knee instability. Level of evidence V.