Accuracy of magnetic resonance imaging in predicting anterior cruciate ligament tear location and tear degree

Magnetic Resonance Imaging of Anterior Cruciate Ligament Injury

The Anterior Cruciate Ligament (ACL) is considered the most commonly injured ligament of the knee. Magnetic Resonance Imaging (MRI) has become an indispensable imaging tool and modality of choice for assessing and managing knee conditions. This article outlines an effective MRI imaging technique that improves the diagnostic accuracy of ACL injuries of the knee, covering the appropriate pulse sequences and optimal imaging planes. Furthermore, the article provides a comprehensive review of the appearance of complete and partial ACL tears on MRI in the acute and chronic phases. In addition, it identifies and illustrates the primary MRI signs (signs related to the absence or abnormal visualization of the ACL fibers) and secondary MRI signs (signs related to the mechanism of injury or associated knee injuries) of ACL injury.

The Functional Integrity of the Anterior Cruciate Ligament Can Be Objectively Assessed With the Use of Stress Radiographs: A Systematic Review

Background

Stress radiography is a viable imaging modality that can also be used to assess the integrity of the anterior cruciate ligament (ACL) after primary or secondary injury. Because conventional radiography is relatively easy, affordable, and available worldwide, the diagnostic efficacy of ACL standing, lateral decubitus, and supine stress radiography should be evaluated.

Purpose

To examine the existing literature regarding the application of stress radiography in evaluating the integrity of the ACL.

Study Design

Systematic review; Level of evidence, 3.

Methods

Using the PubMed and MEDLINE databases for relevant articles published between 1980 and the present, a systematic review was conducted to identify evidence related to the radiographic diagnosis or assessment of ACL tears. The literature search was conducted in September 2022.

Results

Of 495 studies, 16 (1823 patients) were included. Four studies examined standing stress radiography, and 12 investigated lateral decubitus or supine stress radiography. Significant heterogeneity in imaging technique and recorded anterior tibial translation was identified. Anterior tibial translation for ACL-injured knees ranged from 1.2 to 10.6 mm for standing stress radiographs and 2.7 to 11.2 mm for supine stress radiographs, with high sensitivities and specificities for both.

Conclusion

Stress radiography was a dependable diagnostic method for identifying ACL rupture. Further research is necessary to determine the ideal anatomic landmarks, optimal patient positioning, and appropriate applied stresses to establish a standardized protocol for both assessing ACL tears and evaluating the postoperative integrity of ACL reconstruction using stress radiography.

American Academy of Orthopaedic Surgeons Clinical Practice Guideline Case Study: Management of Anterior Cruciate Ligament Injuries

Considering the frequency of anterior cruciate ligament (ACL) tears, optimal management of these injuries was the subject of a 2022 clinical practice guideline update from The American Academy of Orthopaedic Surgeons (AAOS) with input from representatives from the American Orthopaedic Society for Sports Medicine, the Pediatric Orthopaedic Society of North America, the American Orthopaedic Society for Sports Medicine, the American Medical Society for Sports Medicine, the American Academy of Physical Medicine and Rehabilitation, and the American College of Emergency Physicians. The eight recommendations and seven options to guide orthopaedic surgeons and other physicians managing patients with these anterior cruciate ligament injuries are based on the best current available evidence. The cases presented in this article are examples designed to demonstrate the clinical application of these guidelines.

Mechanical and fatigue behaviour of artificial ligaments (ALs)

A flexible biologic band, ACL is the most injured and ruptured ligament in the knees of humans and animals. This research aims to produce synthetic anterior cruciate ligaments (ACLs) and compare these ligaments' mechanical and fatigue life properties with the natural ACL and commercial synthetic grafts. Artificial ligaments were designed as a core-sheath type structure. The core consisted of straight, parallel yarns and the sheath was a tubular fabric produced by weaving or braiding techniques from polyester or Vectran® yarns. The mechanical properties of the resulting artificial ligaments (AL) were tested before and after the fatigue test and compared to those of the natural ACL and commercial artificial ACLs in the market. Results showed that all ligaments had sufficient tensile strength, and they retained it after the fatigue test. If constructed sheath and core parts were from the same type of yarns, the breaking load of ligaments was higher. The breaking strain and stiffness of woven structures, particularly with Vectran cores, were better than braided ones. After the fatigue test, the breaking strain and stiffness of AL structures with a braided sheath or polyester core were improved. This finding suggests that to prevent the laxity of knee preconditioning of the ligament is necessary if the fabric structure or yarn inherently has high breaking strain and low stiffness. Overall, this study shows that a variety of suitable candidates for replacing ruptured anterior cruciate ligaments could be developed by carefully combining the fatigue-resistant yarns with leno, narrow, and braided structures.

The posterior cruciate ligament inclination angle is higher in anterior cruciate ligament insufficiency

PURPOSE

Magnetic resonance imaging (MRI) is the gold standard image examination for anterior cruciate ligament (ACL) lesion diagnosis. Our hypothesis was that measuring the posterior cruciate ligament inclination angle (PCLIA) using MRI images may be an auxiliary tool to aid the recognition of ACL insufficiency. The purpose of this study was to compare the PCLIA measurement in MRIs of individuals with and without ACL injury.

METHODS

The PCLIA was measured by two radiologists in 65 knee MRIs of patients with intact ACL (control group) and in 65 knee MRIs of people with ACL injury (study group). In both groups, the posterior cruciate ligament was intact. The control group was included 35 men (53.8%) and 30 women (46.1%). The patients' average age was 38.7 years (range 15-75; SD ± 14.8 years). In this group, 31 (47.6%) MRIs were from right knees and 34 (52.3%) were from left knees. The study group consisted of 45 men (69.2%) and 20 women (30.7%). The patients' average age was 36.8 years (range 14-55; SD ± 10.3 years). In this group, 33 (50.7%) were right knees and 32 (49.2%) were left knees. PCLIA was formed by the intersection of two lines drawn in MRI sagittal images. The first passed tangentially to the articular surface of the tibial condyle and the second was drawn over the fraction of the ligament that originated where the first crossed the PCL, outlined proximally.

RESULTS

The average PCLIA was 44.2 ± 3.8° in the control group and 78.9 ± 8.6° in the study group. Statistical analyses showed that the PCLIA was higher in the group with ACL injury (p < 0.05). Conclusion The PCLIA was significantly higher in individuals with ACL injuries. The measurement of this angle using MRI images may allow for detection of ACL insufficiency and thus assist in an individualized and precise approach to the treatment of injuries to the ACL.

CLINICAL RELEVANCE

PCLIA may be a way to detect ACL insufficiency and thus help surgeons to decide which patient might need ACL reconstruction.

LEVEL OF EVIDENCE

III.