Radiographic landmarks for locating the femoral origin and tibial insertion of the knee anterolateral ligament

It is challenging to reproduce both anatomical and functional aspects of anterolateral reconstruction: postoperative 3D-CT analysis of the femoral tunnel position

BACKGROUND

This study aimed to evaluate the femoral tunnel position and fiber length of the anterolateral ligament (ALL) reconstruction compared with the natural anatomy of the ALL. We also evaluated whether the femoral tunnel position would affect residual pivot shift.

METHODS

This study was a retrospective review of 55 knees that underwent ALL reconstruction considering the anatomical and functional aspects, during primary anterior cruciate ligament (ACL) reconstruction in the presence of a high-grade pivot shift or revisional ACL reconstruction. We determined the position of the femoral tunnel and the length of graft using a three-dimensional (3D)-computed tomography (CT) model after ALL reconstruction. We also measured graft excursion during surgery and examined pivot shift 2 years after surgery. We conducted a subgroup analysis of femoral tunnel position, fiber length, isometricity, and residual pivot shift depending on whether the tunnel was anterior or posterior to the lateral epicondyle (LE). We also performed a subgroup analysis depending on whether the ACL reconstruction was primary or revisional.

RESULTS

The mean femoral tunnel position was 2.04 mm posterior and 14.5 mm proximal from the center of the LE. The mean lengths of the anterior and posterior fibers were 66.6 and 63.4 mm, respectively. The femoral tunnel was positioned more proximally than the anatomical position, and both anterior and posterior ALL fibers were longer than the natural anatomy. The anteroposterior femoral tunnel position was significantly correlated with anterior (p = 0.045) and posterior (p = 0.037) fiber excursion. In the subgroup analysis, there was no significant difference in the residual pivot shift between the posterior and anterior tunnel positions. However, there were significant differences for proximal position (p < 0.001) and fiber length (p = 0.006). There was no significant difference between primary and revisional ACL regarding femoral tunnel position and fiber lengths.

CONCLUSION

It is challenging to reproduce both anatomical and functional aspects of ALL reconstruction in both primary and revision ACL reconstruction. Especially for functional reconstruction, the femoral tunnel tended to be positioned more proximally than the anatomical position. However, the femoral tunnel position did not affect functional clinical outcomes at the 2-year follow-up.

LEVEL OF EVIDENCE

Level IV Case series.

Magnetic Resonance Imaging Features of Anterolateral Ligament in Young Adults without Anterior Cruciate Ligament Injury: Preliminary Evaluation

This study aimed to characterize the Magnetic Resonance Imaging (MRI) features of the Anterolateral Ligament (ALL) in young adults without Anterior Cruciate Ligament (ACL) injury and evaluate its visibility using MRI. In this retrospective analysis, MRI scans of 66 young adults without ACL injuries were assessed by two radiologists. The ALL was examined from its bone-to-bone attachment between the lateral femoral epicondyle and the lateral tibia. The visibility of the ALL was classified as normal, probably normal, abnormal, or non-visualized, based on ligament continuity and thickness relative to the Meniscotibial Ligament (MTL). A continuous structure with thickness equal to or greater than the MTL was considered normal; continuous but wavy and thin features were categorized as probably normal; discontinuity and angulation were deemed abnormal. The proximal attachment of the ALL was categorized as anterior, central, or posterior to the Fibular Collateral Ligament (FCL), while the distal attachment was noted as either at the same location or distal to the MTL. The ALL was identified in 87.9-95.5% of knees and was non-visualized in 4.5-12.1% of cases. Continuous ligamentous structures were observed in 63.7-71.2% of knees (normal in 30.3-37.9%; probably normal in 27.3-40.9%), whereas 19.7-30.3% exhibited abnormal features. Inter-observer agreement was moderate to substantial (κ = 0.66, 0.56), and intra-observer agreement was substantial to excellent (κ = 0.82, 0.66). Among the 58 visible ALLs, proximal attachments were predominantly anterior (63.8%) or central (32.8%) to the FCL, with a minority posterior (1.7%). In total, 4 of the 19 central insertions were incorporated into the FCL mid-substance, and one case was blended into the meniscofemoral ligament. Distal attachments were equally distributed between the same location (50%) and distal to the MTL (50%) (mean 3.7 mm distal). In conclusion, MRI was feasible for detecting the ALL in most young adults without ACL injury, revealing continuous ligament structures in about two-thirds of cases. Approximately 40% of cases exhibited a thickness equal to or greater than the MTL, with the majority of proximal attachments located anterior to the FCL and distal attachments evenly divided between the same insertion and distal to the MTL.

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.

Combined anterior cruciate ligament revision with reconstruction of the antero-lateral ligament does not improve outcome at 2-year follow-up compared to isolated acl revision; a randomized controlled trial

PURPOSE

It is essential to obtain rotational stability of the knee after anterior cruciate ligament reconstruction (ACL-R) and it is suggested that a supplementary reconstruction of the antero-lateral ligament (ALL-R) may supports this. Theoretically, ALL-R may be particularly advantageous to support revision of failed ACL-Rs. It was hypothesized that ACL revision combined with ALL-R will result in superior outcome compared to isolated ACL revision.

METHODS

The study was designed as a randomized controlled trial. Patients eligible for first time ACL revision were randomized to either isolated ACL revision (- ALL group) or ACL revision combined with a single-stranded allograft ALL-reconstruction (+ ALL group). Patient reported outcomes and function were evaluated at two-year follow-up by KNEES-ACL, KOOS, and Tegner activity scale. Objective knee laxity was evaluated at one-year follow-up using an instrumented Rolimeter test, the pivot shift test, and a manual Lachman test.

RESULTS

A total of 103 patients were enrolled with 49 patients randomized to the + ALL group and 54 patients in the - ALL group. There were no differences at baseline between groups regarding age, gender, body mass index, preoperative patient reported outcome scores and concomitant meniscus or cartilage injury. The ACL revision was performed with an allograft in 10 patients (20%) in the + ALL group and 8 patients (15%) in the -ALL group. At follow-up there was no significant difference between the groups in patient reported outcome scores and clinical knee laxity.

CONCLUSION

Supplementary ALL-R does not improve subjective outcome of first time ACL revision at two-years and clinical knee stability at one-year follow-up compared to isolated ACL revision.

LEVEL OF EVIDENCE

Level I.

Localizing the position of the Segond fracture bed under CT measurements to determine the functional tibial insertion of an anterolateral ligament

Background

Many studies have confirmed the existence of ligament structures in the anterolateral region of the knee that maintain rotational stability of the knee joint, namely, the anterolateral ligament (ALL). Most scholars believe that knee joint reconstruction should be considered during revision surgery and a high level of pivot displacement test (stage 2 or 3). During ALL reconstruction, the choice of ligament reconstruction sites affects the success rate and prognosis of the operation. Therefore, the choice of ligament reconstruction sites is particularly important. There is little research on the lateral ALL tibia insertion point, and most clinicians use the midpoint Gerdy's tubercle and fibular head as insertion points. However, the reconstruction effect is not ideal.

Objective

This study aims to measure the position of the Segond fracture bed on CT images to determine the ALL position of the tibia.

Method

To determine the position of the Segond fracture bone bed, the CT AM Volume Share 2 system was used to manually measure the position of bone fragments in 23 Segond fracture patients. Using the highest point of Gerdy's tubercle in the CT axial slices and the outermost point of the fibular head in the CT axial slices as reference points, the direction and angle of the CT slices were adjusted to ensure that the highest point of the Gerdy tubercle, the outermost point of the fibular head, and the center of Segond fracture bed were in the same sagittal slice. A CT sagittal slice measures the vertical distance from the center of the Segond fracture bed to the Gerdy-fibular line segment (G-F line segment), which is the line connecting the highest point of the segment to the outermost point of the fibula. The distance from the vertical point at the center of the Segond fracture bed of the G-F line to the highest point of the Gerdy tubercle was measured. All measurements were performed using the same measurement standard and were expressed as a percentage of the length of the G-F line. The measured results were statistically analyzed using SPSS 25.0 descriptive statistical research methods.

Results

The average length of the G-F segment measured on CT images was 39.6 ± 2.0 mm, and the average vertical length from the center of the Segond fracture bed to the G-F segment was 13.1 ± 1.1 mm, accounting for 33.2% ± 2.1% of the length of the G-F segment. The length from the vertical point of the fracture bed on the G-F line segment to the highest point of the Gerdy tubercle was 14.7 ± 1.3 mm, accounting for 37.1% ± 2.9% of the length of the G-F segment.

Conclusion

Through the study of the CT measurement of the Segond fracture location, we obtained the location of the functional tibial insertion of ALL, which is different from the anatomical insertion of ALL and is more inclined to the Gerdy tubercle and above, which has reference value for the treatment of recovering the function of anterolateral ligament after reconstruction.

Combined All-Inside Anterior Cruciate Ligament Reconstruction With Semitendinosus Plus Anterolateral Ligament Reconstruction With Intact Gracilis Tibial Insertion and Transtibial Passage

The indications for combining anterior cruciate ligament reconstruction with anterolateral ligament reconstruction have increased considerably in recent years since several anatomical, clinical, and biomechanical studies have proven the importance of the anterolateral periphery in knee rotational stability. Much is still being discussed on how to combine these techniques in terms of which grafts and fixation options to use, as well as avoiding tunnel convergence. This study aims to describe anterior cruciate ligament reconstruction with a triple-bundle semitendinosus tendon graft all-inside technique combined with an anterolateral ligament reconstruction maintaining the gracilis tendon insertion on the tibia, using independent anatomical tunnels. With this, we were able to reconstruct both using only hamstring autografts, reducing morbidity in other possible donor areas, in addition to allowing stable fixation of both grafts without tunnel convergence.

Anatomical and Biomechanical Characteristics of the Anterolateral Ligament: A Descriptive Korean Cadaveric Study Using a Triaxial Accelerometer

Background and Objectives: The anterolateral ligament (ALL) could be the potential anatomical structure responsible for rotational instability after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to investigate the anatomical and biomechanical characteristics of the ALL in Korean cadaveric knee joints. Materials and Methods: Twenty fresh-frozen cadaveric knees were dissected and tested. Femoral and tibial footprints of the ALL were recorded. Pivot shift and Lachman tests were measured with KiRA. Results: The prevalence of ALL was 100%. The average distance of the tibial footprint to the tip of the fibular head was 19.85 ± 3.41 mm; from the tibial footprint to Gerdy's tubercle (GT) was 18.3 ± 4.19 mm; from the femoral footprint to the lateral femoral epicondyle was 10.25 ± 2.97 mm. ALL's footprint distance was the longest at 30° of flexion (47.83 ± 8.05 mm, p < 0.01) in a knee with intact ALL-ACL and neutral rotation. During internal rotation, the footprint distance was the longest at 30° of flexion (50.05 ± 8.88 mm, p < 0.01). Internal rotation produced a significant increase at all three angles after ACL-ALL were transected (p = 0.022), where the footprint distance was the longest at 30° of flexion (52.05 ± 7.60 mm). No significant difference was observed in KiRA measurements between intact ALL-ACL and ALL-transected knees for pivot shift and Lachman tests. However, ACL-ALL-transected knees showed significant differences compared to the intact ALL-ACL and ALL-transected knees (p < 0.01). Conclusions: The ALL was identified as a distinct ligament structure with a 100% prevalence in this cadaveric study. The ALL plays a protective role in internal rotational stability. An isolated ALL transection did not significantly affect the ALL footprint distances or functional stability tests. Therefore, the ALL is thought to act as a secondary supportive stabilizer for rotational stability of the knee joint in conjunction with the ACL.

Imaging Findings of Complications After Lateral Extra-Articular Tenodesis of the Knee: A Current Concepts Review

Background

Despite successful anterior cruciate ligament (ACL) reconstruction, many patients continue to experience persistent anterolateral rotatory instability. Lateral extra-articular tenodesis (LET) is used to address this instability by harvesting a portion of the iliotibial band, passing it underneath the fibular collateral ligament, and attaching it just proximal and posterior to the lateral femoral epicondyle. Based on the most recent clinical evidence, the addition of LET to ACL reconstruction improves clinical outcomes, which has led to an increase in the use of this technique.

Purpose

To provide an overview of the postoperative complications of the LET procedure and their associated imaging findings, with a focus on magnetic resonance imaging (MRI).

Study Design

Narrative review.

Methods

In this scoping review, the authors reviewed available radiographic, computed tomography, and MRI scans of patients who experienced postoperative complications after ACL reconstruction with LET, in which the complication was determined to be from the LET procedure. Images were reviewed and subsequently described by an on-staff musculoskeletal radiologist.

Results

The authors found 9 different complications associated with LET: graft failure, hematoma, infection, chronic pain, tunnel convergence, fixation device migration, muscular hernia, peroneal nerve palsy, and knee stiffness. They supplemented these findings with radiographic evidence from 6 patients.

Conclusion

As extra-articular reconstruction techniques including LET become more popular among orthopaedic surgeons, it is important that radiologists and surgeons be adept at recognizing the normal imaging findings of LET and associated complications.

Effects of the Anterolateral Ligament and Anterior Cruciate Ligament on Knee Joint Mechanics: A Biomechanical Study Using Computational Modeling

Background:

Recent studies on lateral knee anatomy have reported the presence of a true ligament structure, the anterolateral ligament (ALL), in the anterolateral region of the knee joint. However, its biomechanical effects have not been fully elucidated.

Purpose:

To investigate, by using computer simulation, the association between the ALL and anterior cruciate ligament (ACL) under dynamic loading conditions.

Study Design:

Descriptive laboratory study; Level of evidence, 5.

Methods:

The authors combined medical imaging from 5 healthy participants with motion capture to create participant-specific knee models that simulated the entire 12 degrees of freedom of tibiofemoral (TF) and patellofemoral (PF) joint behaviors. These dynamic computational models were validated using electromyographic data, muscle activation data, and data from previous experimental studies. Forces exerted on the ALL with ACL deficiency and on the ACL with ALL deficiency, as well as TF and PF contact forces with deficiencies of the ACL, ALL, and the entire ligament structure, were evaluated under gait and squat loading. A single gait cycle and squat cycle were divided into 11 time points (periods 0.0-1.0). Simulated ligament forces and contact forces were compared using nonparametric repeated-measures Friedman tests.

Results:

Force exerted on the ALL significantly increased with ACL deficiency under both gait- and squat-loading conditions. With ACL deficiency, the mean force on the ALL increased by 129.7% under gait loading in the 0.4 period ( P < .05) and increased by 189% under high flexion during the entire cycle of squat loading ( P < .05). A similar trend of significantly increased force on the ACL was observed with ALL deficiency. Contact forces on the TF and PF joints with deficiencies of the ACL, ALL, and entire ligament structure showed a complicated pattern. However, contact force exerted on TF and PF joints with respect to deficiencies of ACL and ALL significantly increased under both gait- and squat-loading conditions.

Conclusion:

The results of this computer simulation study indicate that the ACL and the ALL of the lateral knee joint act as secondary stabilizers to each other under dynamic load conditions.

Femoral Positioning of the Anterolateral Ligament Graft With and Without Ultrasound Location of the Lateral Epicondyle

BACKGROUND

In anterior cruciate ligament (ACL) reconstruction with anterolateral ligament (ALL) reconstruction, precise positioning of the ALL graft on the femur and tibia is key to achieve rotational control. The lateral femoral epicondyle is often used as a reference point for positioning of the ALL graft and can be located by palpation or with ultrasound guidance.

PURPOSE

To compare the ALL graft positioning on the femoral side between an ultrasound-guided technique and a palpation technique for the location of the lateral epicondyle.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 120 patients receiving a primary combined ACL and ALL reconstruction between June and December 2019 were included. The location of the lateral epicondyle was determined by palpation in the palpation group (n = 60) and with preoperative ultrasound guidance in the ultrasound group (n = 60). Groups were comparable in age, sex, body mass index (BMI), and operated side. The planned positioning of the femoral ALL graft was proximal and posterior to the lateral epicondyle. The effective positioning of the femoral ALL graft was evaluated on postoperative lateral radiographs. The primary outcome was location of the graft in a 10-mm quadrant posterior and proximal to the lateral epicondyle. Results were analyzed in 2 subgroups according to BMI.

RESULTS

All 60 anterolateral grafts (100%) in the ultrasound group were positioned in a 10-mm quadrant posterior and proximal to the lateral epicondyle, as opposed to 52 (87%) in the palpation group (P = .006). Errors in graft positioning with palpation occurred in overweight patients (BMI >25) as well as nonoverweight patients (P = .3).

CONCLUSION

Femoral positioning of the ALL graft posterior and proximal to the lateral epicondyle is more reproducible with ultrasound guidance when compared with palpation alone, regardless of BMI.

Increased Rotatory Laxity after Anterolateral Ligament Lesion in Anterior Cruciate Ligament- (ACL-) Deficient Knees: A Cadaveric Study with Noninvasive Inertial Sensors

The anterolateral ligament (ALL) has been suggested as an important secondary knee restrain on the dynamic laxity in anterior cruciate ligament- (ACL-) deficient knees. Nevertheless, its kinematical contribution to the pivot-shift (PS) phenomenon has not been clearly and objectively defined, and noninvasive sensor technology could give a crucial contribution in this direction. The aim of the present study was to quantify in vitro the PS phenomenon in order to investigate the differences between an ACL-deficient knee and an ACL+ALL-deficient knee. Ten fresh-frozen paired human cadaveric knees (n = 20) were included in this controlled laboratory study. Intact, ACL-deficient, and ACL+ALL-deficient knees were subjected to a manual PS test quantified by a noninvasive triaxial accelerometer (KiRA, OrthoKey). Kinematic data (i.e., posterior acceleration of the tibial lateral compartment) were recorded and compared among the three statuses. Pairwise Student's t-test was used to compare the single groups (p < 0.05). Intact knees, ACL-deficient knees, and ACL+ALL-deficient knees showed an acceleration of 5.3 ± 2.1 m/s², 6.3 ± 2.3 m/s², and 7.8 ± 2.1 m/s², respectively. Combined sectioning of ACL and ALL resulted in a statistically significant acceleration increase compared to both the intact state (p < 0.01) and the ACL-deficient state (p < 0.01). The acceleration increase determined by isolated ACL resection compared to the intact state was not statistically significant (p > 0.05). The ALL sectioning increased the rotatory laxity during the PS after ACL sectioning as measured through a user-friendly, noninvasive triaxial accelerometer.

Comparative Analysis of Sagittal-Plane Radiographic Landmarks Used to Identify the Femoral Attachments of Lateral Knee Structures

PURPOSE

To compare previously described radiographic parameters for the localization of the lateral knee (LK) structures, including the popliteal tendon (Pop), anterolateral ligament (ALL), and lateral collateral ligament (LCL), to determine which method best estimates the femoral attachment of each LK structure.

METHODS

Twenty-nine human cadaveric knee specimens were carefully dissected to identify the LCL, ALL, and Pop. The femoral attachment for each structure was labeled with a radiopaque bead. LK radiographic images were obtained using fluoroscopy. Two radiographic approaches were used to identify each LK structure (Pop-A, Pop-B, LCL-A, LCL-B, ALL-A, and ALL-B) via previously published methods based on radiographic landmarks including the posterior femoral cortex and the Blumensaat line. The identification of radiographic landmarks was performed at 2 different time points by 2 different surgeons to determine the Pearson correlation between values, as well as interobserver and intraobserver reliability and reproducibility. The paired t test was conducted to compare the distance between the actual attachment site (as determined by the bead location) and the 2 radiographically identified estimations of attachment locations.

RESULTS

For the LCL, the mean difference between the actual location and the estimated location via application of the LCL-B method (5.0 ± 2.4 mm) was significantly less than that estimated using the LCL-A method (8.2 ± 3.3 mm, P < .0001). Likewise, the Pop-B (5.7 ± 2.0 mm) and ALL-B (9.3 ± 4.5 mm) methods were shown to have smaller differences between the actual and estimated femoral attachment sites of the Pop insertion and ALL insertion, respectively (P < .0001). Methods for estimating the ALL femoral origin were the worst among the LK structures analyzed, with 90% of estimated values greater than 5 mm from the anatomic origin. Interobserver and intraobserver intraclass correlation coefficients were 0.785 or higher.

CONCLUSIONS

Previously described radiographic methods for localization of the femoral attachment sites of the LK structures resulted in estimated locations that were significantly different from the locations of the radiographic beads placed at the anatomic femoral attachment sites of these structures. Therefore, radiographic methods used to localize the femoral attachments of the LK structures may not be reliable.

CLINICAL RELEVANCE

This study shows the variability of the anatomy of the LK structures and the lack of reproducible radiographic criteria to identify these structures. As a result, there will be decreased reliance on radiographic landmarks to identify the placement of femoral grafts and fixation when reconstructing these structures.

Editorial Commentary: Fluoroscopy Is Seldom Required During Knee Posterolateral Reconstruction

Identifying the structures of the lateral knee is critical during knee posterolateral corner reconstruction. Several methods exist that can help estimate the femoral insertions of these structures on lateral radiographs. However, it is important to recognize the limitations of these methods and that anatomic visualization is often more practical and more accurate. Until percutaneous or more minimally invasive techniques become standardized, intraoperative fluoroscopy is seldom needed or used for posterolateral corner reconstruction, whereas radiographic analysis of lateral knee structures could be of benefit in cases of failed reconstruction to assess tunnel placement.

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.

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?

The anterolateral ligament is a secondary stabilizer in the knee joint: A validated computational model of the biomechanical effects of a deficient anterior cruciate ligament and anterolateral ligament on knee joint kinematics

Objectives

The aim of this study was to investigate the biomechanical effect of the anterolateral ligament (ALL), anterior cruciate ligament (ACL), or both ALL and ACL on kinematics under dynamic loading conditions using dynamic simulation subject-specific knee models.

Methods

Five subject-specific musculoskeletal models were validated with computationally predicted muscle activation, electromyography data, and previous experimental data to analyze effects of the ALL and ACL on knee kinematics under gait and squat loading conditions.

Results

Anterior translation (AT) significantly increased with deficiency of the ACL, ALL, or both structures under gait cycle loading. Internal rotation (IR) significantly increased with deficiency of both the ACL and ALL under gait and squat loading conditions. However, the deficiency of ALL was not significant in the increase of AT, but it was significant in the increase of IR under the squat loading condition.

Conclusion

The results of this study confirm that the ALL is an important lateral knee structure for knee joint stability. The ALL is a secondary stabilizer relative to the ACL under simulated gait and squat loading conditions.Cite this article: Bone Joint Res 2019;8:509-517.

Biomechanical Effects of Additional Anterolateral Structure Reconstruction With Different Femoral Attachment Sites on Anterior Cruciate Ligament Reconstruction

BACKGROUND

Recently reported anterolateral structure reconstructions (ALSRs) to augment intra-articular anterior cruciate ligament reconstruction (ACLR) use various femoral attachment sites, and their biomechanical effects are still unknown.

HYPOTHESIS

ALSR concomitant with ACLR would control anterolateral rotational instability better than ACLR alone, and if ALSR had different femoral attachment sites, there would be different effects on its control of anterolateral rotational instability.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve fresh-frozen hemipelvis lower limbs were included. Anterior tibial translation during the Lachman test and tibial acceleration during the pivot-shift test were measured with a 3-dimensional electromagnetic measurement system in situations with the (1) ACL and ALS intact, (2) ACL and ALS cut, (3) ALSR without ACLR (ALSR alone), (4) ACLR without ALSR (ACLR alone), and (5) ALSR with ACLR. Three femoral attachment sites were used for ALSR: F1, 2 mm anterior and 2 mm distal to the lateral epicondyle; F2, 4 mm posterior and 8 mm proximal to the lateral epicondyle; and F3, over-the-top position for the lateral extra-articular tenodesis. The Steel test and Wilcoxon signed rank test were used for statistical analysis.

RESULTS

Anterior tibial translation during the Lachman test in the ACL and ALS-cut state was significantly larger than it was in the ACL and ALS-intact state, while its difference disappeared after ACLR. As for the pivot-shift test, additional ALSR with F2 to ACLR significantly decreased the acceleration (P = .046), although additional ALSR with F1 and F3 showed no significant effect.

CONCLUSION

ALSR with the femoral attachment site 4 mm posterior and 8 mm proximal to the lateral epicondyle in addition to ACLR played a role in reducing anterolateral rotational instability the most effectively among the measured attachment sites.

CLINICAL RELEVANCE

The present data will contribute to determine the appropriate femoral attachment site for ALSR to better control anterolateral rotational instability after ACL reconstruction.

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.

Identification of Normal and Injured Anterolateral Ligaments of the Knee: A Systematic Review of Magnetic Resonance Imaging Studies

PURPOSE

To identify the normal and injured magnetic resonance imaging appearance of the anterolateral ligament (ALL).

METHODS

A systematic review was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The PubMed and Cochrane Library electronic databases were used to search for studies that reported the imaging outcomes of the appearance of the ALL. Two authors performed the searches in duplicate up to April 30, 2018, and interobserver agreement was calculated. The methodologic quality of included articles was assessed using an adaptation of the Arrivé methodologic quality scale for clinical studies of radiologic examinations.

RESULTS

From the original 270 records, a total of 24 studies (κ = 0.94) comprising 2,427 knees in 2,388 patients (mean age, 33.3 years; 66% male patients; 63% with anterior cruciate ligament [ACL] injury) were included. The ALL appeared in 51% to 100% of all assessed knees (71%-100% in ACL-injured knees and 64%-97% in uninjured knees) and was injured in 11% to 79% of ACL-injured knees. Reliability rates varied considerably (0.04-1.0 for intraobserver and 0.143-1.0 for interobserver agreement), and the entire portion of the ligament was often not seen. The tibial insertion was seen in 21% to 96% of cases, followed by the meniscal (range, 0%-100%) and femoral (range, 0%-90%) insertions. The mean methodologic quality score was 5.1 ± 1.8 out of a possible score of 9.

CONCLUSIONS

High variability was found in the identification of normal and injured ALL definition methods and the respective magnetic resonance imaging findings. Reliability rates varied considerably, and the entire portion of the ligament was often not seen.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II to IV studies.

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.

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.

Combined reconstruction of the anterolateral ligament in chronic ACL injuries leads to better clinical outcomes than isolated ACL reconstruction

PURPOSE

To evaluate the results of combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction in patients with chronic ACL injury. It was hypothesized that patients who underwent combined ACL and ALL reconstruction would exhibit less residual laxity and better clinical outcomes.

METHODS

Two groups of patients were evaluated and compared retrospectively. Both groups consisted only of patients with chronic (more than 12 months) ACL injuries. Patients in group 1 underwent anatomical intra-articular reconstruction of the ACL and patients in group 2 underwent anatomic intra-articular ACL reconstruction combined with ALL reconstruction. The presence of associated meniscal injury, the subjective International Knee Documentation Committee (IKDC) and Lysholm functional outcome scores in the postoperative period, KT-1000 evaluation, the presence of residual pivot shift and graft rupture rate were evaluated.

RESULTS

One hundred and one patients who underwent reconstruction of chronic ACL injuries were evaluated. The median follow-up was 26 (24-29) months for group 1 and 25 (24-28) months for group 2. There were no significant differences between groups regarding gender, age, duration of injury until reconstruction, follow-up time or presence of associated meniscal injuries in the preoperative period. Regarding functional outcome scores, patients in group 2 presented better results on both the IKDC (p = 0.0013) and the Lysholm (p < 0.0001) evaluations. In addition, patients in group 2 had better KT-1000 evaluation (p = 0.048) and a lower pivot shift rate at physical examination, presenting only 9.1% positivity versus 35.3% in the isolated ACL reconstruction (p = 0.011). Regarding re-ruptures, group 1 presented 5 (7.3%) cases, and group 2 presented no cases.

CONCLUSION

The combined ACL and ALL reconstruction in patients with chronic ACL injury is an effective and safety solution and leads to good functional outcomes with no increase in complication rate. The clinical relevance of this finding is the possibility to indicate this type of procedure when patients present with more than 12 months after injury for surgery.

LEVEL OF EVIDENCE

Level III.

Assessment of the Anterolateral Ligament of the Knee by Magnetic Resonance Imaging

Purpose  The purpose of this study was to describe the anatomy of the anterolateral ligament (ALL) of the knee by the use of 1.5 Tesla (T) magnetic resonance imaging (MRI) in a series of young patients without knee injuries.

Methods  Subjects aged 18 years or older without an anterior cruciate ligament injury, as confirmed on MRI, were included. MRI examinations were all performed on 1.5 T scans. The ALL was defined as the low signal band originating from the region of the lateral epicondyle of the femur, crossing the proximal surface of the lateral collateral ligament, deep to the iliotibial band, and inserting onto the tibia between the Gerdy's tubercle and the fibular head.

Results  Twenty-six patients met the eligibility criteria and were enrolled into the study. In one patient, it was not possible to visualize the ALL. In all the other subjects, the ligament originated anterior and distal to the lateral epicondyle and inserted on the proximal tibia approximately 5 mm below the joint line and just distal to the Gerdy's tubercle. It had an average length of 33 ± 1.2 mm, an average width of 5.5 ± 0.3 mm, and an average thickness of 2 mm.

Conclusion  The ALL is a distinct structure of the anterolateral capsule that can be easily identified using 1.5 T MRI scans.

Level of Evidence  This is a level IV, observational study.

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.

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.

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.

Ultrasonographic assessment of the anterolateral ligament of the knee in healthy subjects

Objective

The aim of our study was to determine inter-observer agreement in the ultrasonographic identification of the anterolateral ligament (ALL) and in the evaluation of its length and thickness in healthy subjects.

Methods

80 healthy volunteers (160 knees) (42 males and 38 females) were enrolled in the study. All subjects underwent ultrasound (US) examination of both knees, performed by two physicians with over ten years of musculoskeletal US experience. In order to keep the ALL under optimal tension, the knee was flexed at approximately 30-35°, slightly internally rotated and length and thickness of the ligament were measured.

Results

ALL was identified in 93.8% (150 out of 160) and in 92.5% (148 out of 160) of the knees by Evaluator 1 and Evaluator 2, respectively. Interobserver agreement was substantial to almost perfect for the visualization of the ALL ( =0.90) and for measurements of its length (ICC = 0.83), and strong for measurements of its thickness (ICC = 0.75).

Conclusion

In our study on healthy subjects, ALL has been visualized with a high rate of reproducibility. Further studies are needed to see if US may be a reliable and reproducible diagnostic tool in patients with traumatic or degenerative knee disorders.

Level of evidence

II, evidence obtained from cohort study.

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.

An Overview of Clinically Relevant Biomechanics of the Anterolateral Structures of the Knee

Residual anterolateral rotatory laxity following injury and reconstruction of the anterior cruciate ligament (ACL) has become a popular topic and has generated interest in characterizing the relative contribution from the anterolateral structures of the knee. Studies have reported on the anatomic and biomechanical features of the anterolateral ligament (ALL), revealing a role in restraining internal tibial rotation in both ACL-intact and ACL-deficient knees. The Kaplan fibers of the iliotibial band have also been reported to provide significant restraint to internal tibial rotation. The ACL is the primary restraint to anterior tibial translation, and both the proximal and distal bundles of the iliotibial band, with a divergent orientation, also provide significant static restraint against internal tibial rotation, and each bundle may have a distinct individual role. In the setting of ACL deficiency, subsequent sectioning of the ALL and Kaplan fibers led to further increases in anterior tibial translation. Residual rotatory laxity that may be seen clinically following ACL reconstruction may be attributable to an associated anterolateral structure injury even in the setting of an anatomic ACLR, leading to consideration for a concomitant anterolateral structure reconstruction. Studies evaluating the kinematic influence of anatomic ALL reconstruction or lateral extra-articular tenodesis have focused on internal rotation, axial plane translation, and anterior tibial translation, with variable results having been reported. Further, despite the long history of anterolateral structure reconstruction, most commonly with a lateral extra-articular tenodesis, the clinical use of these combined techniques is still in its relative infancy, and long-term patient outcomes have yet to be published for relative comparisons.

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.

A Comprehensive Reanalysis of the Distal Iliotibial Band: Quantitative Anatomy, Radiographic Markers, and Biomechanical Properties

BACKGROUND

The qualitative anatomy of the distal iliotibial band (ITB) has previously been described. However, a comprehensive characterization of the quantitative anatomic, radiographic, and biomechanical properties of the Kaplan fibers of the deep distal ITB has not yet been established. It is paramount to delineate these characteristics to fully understand the distal ITB's contribution to rotational knee stability. Purpose/Hypothesis: There were 2 distinct purposes for this study: (1) to perform a quantitative anatomic and radiographic evaluation of the distal ITB's attachment sites and their relationships to pertinent osseous and soft tissue landmarks, and (2) to quantify the biomechanical properties of the deep (Kaplan) fibers of the distal ITB. It was hypothesized that the distal ITB has definable parameters concerning its anatomic attachments and consistent relationships to surgically pertinent landmarks with correlating plain radiographic findings. In addition, it was hypothesized that the biomechanical properties of the Kaplan fibers would support their role as important restraints against internal rotation.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten nonpaired, fresh-frozen human cadaveric knees (mean age, 61.1 years; range, 54-65 years) were dissected for anatomic and radiographic purposes. A coordinate measuring device quantified the attachment areas of the distal ITB to the distal femur, patella, and proximal tibia and their relationships to pertinent bony landmarks. A radiographic analysis was performed by inserting pins into the attachment sites of relevant anatomic structures to assess their location relative to pertinent bony landmarks with fluoroscopic guidance. A further biomechanical assessment of 10 cadaveric knees quantified the load to failure and stiffness of the Kaplan fibers' insertion on the distal femur after a preconditioning protocol.

RESULTS

Two separate deep (Kaplan) fiber bundles were identified with attachments to 2 newly identified femoral bony prominences (ridges). The proximal and distal bundles inserted on the distal femur 53.6 mm (95% CI, 50.7-56.6 mm) and 31.4 mm (95% CI, 27.3-35.5 mm) proximal to the lateral epicondyle, respectively. The centers of the bundle insertions were 22.5 mm (95% CI, 19.1-25.9 mm) apart. The total insertion area of the distal ITB on the proximal tibia was 429.1 mm² (95% CI, 349.2-509.1 mm²). A distinct capsulo-osseous layer of the distal ITB was also identified that was intimately related to the lateral knee capsule. Its origin was in close proximity to the lateral gastrocnemius tubercle, and it inserted on the proximal tibia at the lateral tibial tubercle between the fibular head and the Gerdy tubercle. Radiographic analysis supported the quantitative anatomic findings. The mean maximum load during pull-to-failure testing was 71.3 N (95% CI, 41.2-101.4 N) and 170.2 N (95% CI, 123.6-216.8 N) for the proximal and distal Kaplan bundles, respectively.

CONCLUSION

The most important finding of this study was that 2 distinct deep bundles (Kaplan fibers) of the distal ITB were identified. Each bundle of the deep layer of the ITB was associated with a newly identified distinct bony ridge. Radiographic analysis confirmed the measurements previously recorded and established reproducible landmarks for the newly described structures. Biomechanical testing revealed that the Kaplan fibers had a strong attachment to the distal femur, thereby supporting a role in rotational knee stability.

CLINICAL RELEVANCE

The identification of 2 distinct deep fiber (Kaplan) attachments clarifies the function of the ITB more definitively. The results also support the role of the ITB in rotatory knee stability because of the fibers' vectors and their identified maximum loads. These findings provide the anatomic and biomechanical foundation needed for the development of reconstruction or repair techniques to anatomically address these deficiencies in knee ligament injuries.

Combined Anatomic Anterior Cruciate Ligament and Double Bundle Anterolateral Ligament Reconstruction

The results of arthroscopic anterior cruciate ligament (ACL) reconstruction are so far satisfactory and improving over time as a result of the improved understanding of the anatomy and biomechanics of the ACL. Rotational instability confirmed by a positive pivot shift is present in more than 15% of cases who underwent successful ACL reconstruction. Persistent rotational instability interferes with performing pivoting sports, and also may lead to meniscal and chondral injuries, or re-rupture of the reconstructed ACL. Surgeons reconsidered the anatomy and biomechanics of the ACL and introduced the double bundle ACL reconstruction technique aiming to achieve a more rotational control by reconstructing the anteromedial and anterolateral bundles of the ACL. To date, the results of double bundle ACL reconstruction are mixed and inconsistent. The improved understanding of the existence, function, and biomechanical role of the anterolateral ligament (ALL) in controlling the rotational instability of the knee has redirected and refocused attention on a supplemental extra-articular reconstruction of the ALL in conjunction with the intra-articular ACL reconstruction so as to restore normal kinematics of the knee. In this Technical Note, we describe a technique that allows for a combined ACL and double bundle ALL reconstruction using autogenous hamstring graft (semitendinosus and gracilis) tendons. This technique is an extension of our previously described technique of a combined anatomic ACL and single bundle ALL reconstruction. The improved understanding of the anatomy of the ALL makes a double bundle ALL reconstruction more anatomic than single bundle ALL reconstruction, as the native ALL is triangular or inverted Y in shape, with a narrow proximal femoral attachment and a broad distal tibial attachment between Gerdy's tubercle and the head of the fibula.

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.

Segond's fracture: a biomechanical cadaveric study using navigation

Background

Segond’s fracture is a well-recognised radiological sign of an anterior cruciate ligament (ACL) tear. While previous studies evaluated the role of the anterolateral ligament (ALL) and complex injuries on rotational stability of the knee, there are no studies on the biomechanical effect of Segond’s fracture in an ACL deficient knee. The aim of this study was to evaluate the effect of a Segond’s fracture on knee rotation stability as evaluated by a navigation system in an ACL deficient knee.

Materials and methods

Three different conditions were tested on seven knee specimens: intact knee, ACL deficient knee and ACL deficient knee with Segond’s fracture. Static and dynamic measurements of anterior tibial translation (ATT) and axial tibial rotation (ATR) were recorded by the navigation system (2.2 OrthoPilot ACL navigation system B. Braun Aesculap, Tuttlingen, Germany).

Results

Static measurements at 30° showed that the mean ATT at 30° of knee flexion was 5.1 ± 2.7 mm in the ACL intact condition, 14.3 ± 3.1 mm after ACL cut (P = 0.005), and 15.2 ± 3.6 mm after Segond’s fracture (P = 0.08). The mean ATR at 30° of knee flexion was 20.7° ± 4.8° in the ACL intact condition, 26.9° ± 4.1° in the ACL deficient knee (P > 0.05) and 30.9° ± 3.8° after Segond’s fracture (P = 0.005). Dynamic measurements during the pivot-shift showed that the mean ATT was 7.2 ± 2.7 mm in the intact knee, 9.1 ± 3.3 mm in the ACL deficient knee(P = 0.04) and 9.7 ± 4.3 mm in the ACL deficient knee with Segond’s fracture (P = 0.07). The mean ATR was 9.6° ± 1.8° in the intact knee, 12.3° ± 2.3° in the ACL deficient knee (P > 0.05) and 19.1° ± 3.1° in the ACL deficient knee with Segond’s lesion (P = 0.016).

Conclusion

An isolated lesion of the ACL only affects ATT during static and dynamic measurements, while the addition of Segond’s fracture has a significant effect on ATR in both static and dynamic execution of the pivot-shift test, as evaluated with the aid of navigation.

Anterolateral Ligament Expert Group consensus paper on the management of internal rotation and instability of the anterior cruciate ligament - deficient knee

Purpose of this paper is to provide an overview of the latest research on the anterolateral ligament (ALL) and present the consensus of the ALL Expert Group on the anatomy, radiographic landmarks, biomechanics, clinical and radiographic diagnosis, lesion classification, surgical technique and clinical outcomes. A consensus on controversial subjects surrounding the ALL and anterolateral knee instability has been established based on the opinion of experts, the latest publications on the subject and an exchange of experiences during the ALL Experts Meeting (November 2015, Lyon, France). The ALL is found deep to the iliotibial band. The femoral origin is just posterior and proximal to the lateral epicondyle; the tibial attachment is 21.6 mm posterior to Gerdy's tubercle and 4-10 mm below the tibial joint line. On a lateral radiographic view the femoral origin is located in the postero-inferior quadrant and the tibial attachment is close to the centre of the proximal tibial plateau. Favourable isometry of an ALL reconstruction is seen when the femoral position is proximal and posterior to the lateral epicondyle, with the ALL being tight upon extension and lax upon flexion. The ALL can be visualised on ultrasound, or on T2-weighted coronal MRI scans with proton density fat-suppressed evaluation. The ALL injury is associated with a Segond fracture, and often occurs in conjunction with acute anterior cruciate ligament (ACL) injury. Recognition and repair of the ALL lesions should be considered to improve the control of rotational stability provided by ACL reconstruction. For high-risk patients, a combined ACL and ALL reconstruction improves rotational control and reduces the rate of re-rupture, without increased postoperative complication rates compared to ACL-only reconstruction. In conclusion this paper provides a contemporary consensus on all studied features of the ALL. The findings warrant future research in order to further test these early observations, with the ultimate goal of improving the long-term outcomes of ACL-injured patients. Level of evidence Level V-Expert opinion.

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.

A New Reconstructive Technique of the Anterolateral Ligament with Iliotibial Band-Strip

Background:

Anterior cruciate ligament (ACL) reconstruction is a well-established surgical procedure for the correction of ACL ruptures. However, the incidence of instability following ACL reconstruction is substantial. Recent studies have led to greater insight into the anatomy and the radiographic characteristics of the native anterolateral ligament (ALL), along with its possible role in residual instability after ACL reconstruction.

Method:

The current paper describes a lateral extra-articular tenodesis to reconstruct the ALL during ACL procedures, using a short iliotibial band strip. The distal insertion of this strip is left intact on the anterolateral side of the proximal tibia, and the proximal part is fixed at the anatomic femoral insertion of the ALL.

Results:

Our technique avoids the sacrifice of one of the hamstring tendons for the ALL reconstruction. Additionally, there is no interference with the anatomical location or function of the LCL.

Conclusion:

Our technique offers a minimally invasive and nearly complete anatomical reconstruction of the ALL with minimal additional operative time.

Combined Anatomic Reconstruction of the Anterior Cruciate and Anterolateral Ligaments Using Hamstring Graft Through a Single Femoral Tunnel and With a Single Femoral Fixation

Patients with complete anterior cruciate ligament (ACL) injury have different degrees of rotational (internal rotation) laxity. A residual pivot shift has been found to be positive in more than 15% of cases after an accurate ACL reconstruction. Improved understanding of the existence, function, and biomechanical role of the anterolateral ligament (ALL) in controlling rotational instability of the knee has redirected and refocused attention on a supplemental extra-articular reconstruction of the ALL in conjunction with the intra-articular ACL reconstruction so as to restore normal kinematics of the knee. This Technical Note describes a technique that allows for a combined ACL and ALL reconstruction using autogenous hamstring graft (semitendinosus and gracilis tendons). One femoral tunnel is used connecting the anatomic femoral attachment of the ALL on the lateral wall of the lateral femoral condyle to the anatomic femoral ACL footprint on the medial wall of the lateral femoral condyle. The remaining part of the graft is fixed to the proximal tibia midway between Gordy's tubercle and the head of the fibula. This Technical Note describes a technique of both ACL and ALL reconstruction with a continuous hamstring graft.

The Anterolateral Ligament Has Similar Biomechanical and Histologic Properties to the Inferior Glenohumeral Ligament

PURPOSE

To characterize the tensile and histologic properties of the anterolateral ligament (ALL), inferior glenohumeral ligament (IGHL), and knee capsule.

METHODS

Standardized samples of the ALL (n = 19), anterolateral knee capsule (n = 15), and IGHL (n = 13) were isolated from fresh-frozen human cadavers for uniaxial tensile testing to failure. An additional 6 samples of the ALL, capsule, and IGHL were procured for histologic analysis and determination of elastin content.

RESULTS

All investigated mechanical properties were significantly greater for both the ALL and IGHL when compared with capsular tissue. In contrast, no significant differences between the ALL and IGHL were found for any property. The elastic modulus of ALL and IGHL samples was 174 ± 92 MPa and 139 ± 60 MPa, respectively, compared with 62 ± 30 MPa for the capsule (P = .001). Ultimate stress was significantly lower (P < .001) for the capsule, at 13.4 ± 7.7 MPa, relative to the ALL and IGHL, at 46.4 ± 20.1 MPa and 38.7 ± 16.3 MPa, respectively. The ultimate strain at failure was 37.8% ± 7.9% for the ALL and 39.5% ± 9.4% for the IGHL; this was significantly greater (P = .041 and P = .02, respectively) for both relative to the capsule, at 32.6% ± 8.4%. The strain energy density was 7.8 ± 3.1 MPa for the ALL, 2.1 ± 1.3 MPa for the capsule, and 7.1 ± 3.1 MPa for the IGHL (P < .001). The ALL and IGHL consisted of collagen bundles aligned in a parallel manner, containing elastin bundles, which was in contrast to the random collagen architecture noted in capsule samples.

CONCLUSIONS

The ALL has similar tensile and histologic properties to the IGHL. The tensile properties of the ALL are significantly greater than those observed in the knee capsule. CLINICAL RELEVANCE: The ALL is not just a thickening of capsular tissue and should be considered a distinct ligamentous structure comparable to the IGHL in the shoulder. The tensile behavior of the ALL is similar to the IGHL, and treatment strategies should take this into account.

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

BACKGROUND

The anterolateral ligament (ALL) of the knee has been identified as a structure that limits internal rotation, and thus, affects the pivot shift mechanism. It has previously been reported in a high percentage of adult subjects. The purpose of the current study was to evaluate whether the ALL could be identified on pediatric cadaveric knee specimens and compare these findings to previously published reports.

METHODS

Eight skeletally immature cadaver knee specimens were examined through gross dissection: ages 3 months, 4 months, 1 year, 2 years, 3 years, 3 years, 8 years, and 10 years. There were 3 male and 5 female (7 right, 1 left) specimens. The presence or absence of the ALL was documented in each specimen, through dissection, intermittent internal and external rotation of the tibia, and anterior translation of the tibia, to produce tension of the lateral collateral tissues and joint capsule. These dissections were performed by a group of fellowship-trained orthopaedic surgeons.

RESULTS

The iliotibial band, entire lateral joint capsule, lateral collateral ligament, and popliteus were readily identified in each specimen. In 7 specimens, a distinct ALL structure was not identified during dissection. The ALL was identified in 1 of 8 specimens (1-year-old female, right knee). The ALL was further delineated under applied internal rotational stress.

CONCLUSIONS

Previous research has suggested that this ligament is present in the majority of adult specimens. This finding was not reproduced in the current study of pediatric cadaveric specimens, where only one of 8 specimens had an identifiable ALL. This suggests that this ligament may develop later in life, after physiological loads are applied to the joint capsule. Further research in both adult and pediatric knees needs to be conducted to further elucidate the development of this ligament, and the role of this structure in knee stability.

CLINICAL RELEVANCE

The ALL is a knee ligament that has been described in adults. However, it is unclear whether this structure is present or fully developed in younger populations. The current study sought to identify the ALL in pediatric cadaver knee specimens, identifying this structure in only one of 8 specimens. The findings of this study suggest that the ALL may be an inconsistent structure in the pediatric population.

Patients with high-grade pivot-shift phenomenon are associated with higher prevalence of anterolateral ligament injury after acute anterior cruciate ligament injuries

PURPOSE

To compare the prevalence of concomitant anterolateral ligament (ALL) injury between patients with high-grade (grades II and III) pivot-shift and those with low-grade (grades 0 and I) pivot-shift phenomenon after acute anterior cruciate ligament (ACL) injuries.

METHODS

Sixty-eight patients with an acute ACL injury who showed high-grade (grades II and III) pivot-shift phenomenon were enrolled as the study group. They were matched in a 1:1 fashion to another 68 ACL-injured control participants who showed low-grade (grades 0 and I) pivot-shift phenomenon during the same study period. Patients were matched by age, sex, and time from injury to surgery. A standardized pivot-shift test was performed under anesthesia for all the patients. Two blinded musculoskeletal radiologists reviewed the magnetic resonance imaging (MRI) scans for the presence of concomitant ALL injury. The grade of an ALL injury was divided into grade 0 (normal), grade I (sprain), grade II (partial tear), and grade III (complete tear). The prevalence and the grade of concomitant ALL injury were further compared between the study group and the control group.

RESULTS

Overall, the prevalence of concomitant ALL injury in the study group (94.1%, 64/68) was significantly higher than that in the control group [60.3%, (41/68), P < 0.05]. Specifically, there were 49 patients (49/64, 76.6%) who showed grade II/III (partial/complete tear) MRI evidence of concomitant ALL injury, which was also significantly higher than that in the control group (12/41, 29.3%).

CONCLUSIONS

Patients with high-grade pivot-shift phenomenon showed higher prevalence of concomitant ALL injury compared to those with low-grade pivot-shift phenomenon after acute ACL injuries. Careful assessment and proper treatment of this concomitant injury should be considered especially in knees with high-grade pivot-shift phenomenon.

LEVEL OF EVIDENCE

III.

Sectioning the anterolateral ligament did not increase tibiofemoral translation or rotation in an ACL-deficient cadaveric model

PURPOSE

The anterolateral ligament (ALL) has been proposed as a possible extra-articular stabiliser of the knee. Injury to the ALL may result in residual instability following surgical reconstruction of a ruptured anterior cruciate ligament (ACL). Few studies have evaluated the biomechanical role of the ALL. The purpose of this study was to investigate whether sectioning the ALL would have an influence on tibiofemoral translation or rotation during the anterior drawer, Lachman, pivot shift, external rotation, and internal rotation tests in an ACL-deficient knee.

METHODS

Only whole-body specimens having an ALL were included in this study. Lachman, anterior drawer, external rotation, and internal rotation tests were performed manually. Pivot shift test was done using a mechanised pivot shifter. The amount of tibiofemoral translation and rotation was recorded by a navigation system. Each specimen was tested in its native state, after sectioning the ACL, and after combined sectioning of the ACL and the ALL.

RESULTS

In six out of 14 cadaveric knees, an ALL could be identified. The ACL-deficient knee had significantly more tibiofemoral translation and rotation compared to the native knee (P < 0.05). However, no changes in the magnitudes of translation or rotation were seen after subsequent sectioning of the ALL compared to the ACL-deficient knee (P > 0.05).

CONCLUSION

Adding an ALL lesion in an ACL-deficient knee did not increase tibiofemoral instability in this cadaveric model. It remains unclear whether injury to the ALL would result in substantial knee instability in the setting of ACL injury in vivo. Further research is warranted to fully elucidate the role of the ALL during knee kinematics and to determine in which scenarios ALL repair would be warranted. Understanding the function of the ALL may improve the current treatment strategies for ACL ruptures.