The Anterolateral Ligament of the Knee: What the Radiologist Needs to Know

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.

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.

Imaging Diagnosis of Injury to the Anterolateral Ligament in Patients With Anterior Cruciate Ligaments: Association of Anterolateral Ligament Injury With Other Types of Knee Pathology and Grade of Pivot-Shift Examination: A Systematic Review

PURPOSE

The purpose of this study is to systematically review the literature to evaluate the reliability, or the ability of a repeated measurement to yield consistent results, and validity of ultrasound (US) and magnetic resonance imaging (MRI) at evaluating anatomy and pathology of the anterolateral ligament of the knee (ALL) in the setting of anterior cruciate ligament (ACL) injuries. Furthermore, the incidence and association of ALL injury with the pivot-shift examination, and other structural injuries, will be reviewed for additional clinical relevance.

METHODS

Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 2 reviewers independently searched the Medline, Embase, Cochrane, EBSCOhost, OVID, and Web of Science databases for all studies related to imaging of the ALL. All eligible articles and their references were screened by both reviewers. Studies discussing diagnostic imaging of the ALL with regard to identification of injury to the structure in patients with suspected ACL injury were included. No restrictions regarding date of publication, type of publication, or language in the included article were applied. The exclusion criteria included commentaries, case reports, and studies that did not attempt to identify the ALL as a discrete structure. Quality assessment and data extraction was performed for each included study before final analysis was performed.

RESULTS

A total of 13 articles were included for final analysis. In the included studies, at least 1 portion of the ALL could be visualized on MRI in 76% to 100% of knees, and injury to the ALL was identified in 10.8% to 62.5% of patients. Inter- and intraobserver reliabilities ranged from moderate to almost perfect. There was a consensus among studies that ALL injuries were significantly associated with injuries to the lateral collateral ligament, popliteus tendon, iliotibial band, and bony contusions to the lateral tibia and femur. Most of the included studies found a significant association of injuries to the ALL and a high-grade pivot-shift examination. Only 2 studies used US to evaluate for injury to the ALL, and both studies had almost perfect interobserver reliability. Only 1 study confirmed initial diagnoses at the time of the ACL reconstruction surgery.

CONCLUSIONS

In patients with ACL injuries, concomitant ALL injuries can be identified on MRI or US with high levels of inter- and intraobserver reliability, and are often associated with a high-grade pivot-shift examination, lateral collateral ligament injury, and lateral femoral condyle and tibial plateau bone bruises.

LEVEL OF EVIDENCE

Level IV, systematic review of level II-IV studies.

The magnetic resonance imaging appearance of the anterolateral ligament of the knee in association with anterior cruciate rupture

OBJECTIVE

The magnetic resonance imaging (MRI) appearance of the anterolateral ligament (ALL) has been described. However, the appearance of this structure and injury, in the presence of anterior cruciate ligament (ACL) injury, is less well defined. We studied the incidence of injury to the ALL and the pattern of this injury on MRI.

MATERIALS AND METHODS

Following Institutional Review Board approval, a retrospective study of 375 consecutive MRI studies was performed. Cases were identified from a prospective database of ACL reconstruction patients. Following exclusions, 280 MRIs (277 patients; 197 males: 80 females; mean age 30.2 years, range, 16-54) were evaluated. Injury was defined as full thickness, partial thickness, or an avulsion fracture. Each study was independently assessed by two consultant musculoskeletal radiologists.

RESULTS

Injury to the ALL was identified (by at least one observer) in only 10.7% of cases (2.50% full thickness, 7.50% partial thickness, and 0.71% avulsion fracture). There was an almost perfect level of interobserver agreement for both the identification of an injury (κ = 0.854) and grading of injury (κ = 0.858). The MRI incidence of ALL injury was significantly greater within 6 weeks of the knee injury (18.5 vs. 8.37%; p < 0.05).

CONCLUSIONS

ALL injury was identified in only one-tenth of cases of ACL rupture. MRI changes can be reliably identified with strong agreement between observers. ALL injury is found more frequently on MRI within 6 weeks of the knee injury (compared to scans performed after this time period) suggesting that some injuries may resolve or become less visible.

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.

The Annual Scientific Meeting of the European Society of Musculoskeletal Radiology (ESSR) 2016 in Zurich, Switzerland: summary

The 23rd Annual Scientific Meeting of the European Society of Musculoskeletal Radiology (ESSR) 2016 in Switzerland, Zurich will be summarized.