Anatomic Measurement and Variability Analysis of the Anterior Talofibular Ligament and Calcaneofibular Ligament of the Ankle

Anatomic Variations of the Calcaneofibular Ligament

BACKGROUND

The lateral ankle joint comprises the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and posterior talofibular ligament (PTFL). The purpose of this study was to propose a classification of CFL morphology.

METHODS

The material comprised 120 paired lower limbs from human cadavers (30 male, 30 female), mean age 62.3 years. The morphology was carefully assessed, and morphometric measurements were performed.

RESULTS

A 4-part method for anatomic classification can be suggested based on our study. Type 1 (48.3%), the most common type, was characterized by a bandlike morphology. Type 2 (9.2%) was characterized by a Y-shaped band, and type 3 (21.7%) by a V-shaped band. Type 4 (20.8%) was characterized by the presence of 2 or 3 bands. Type 2 and 4 were divided into further subtypes based on origin footprint.

CONCLUSION

The aim of our study was to describe variations of calcaneofibular ligament. Our proposed 4-part classification may be of value in clinical practice in future recognition of CFL injuries and in its repair or reconstruction.

CLINICAL RELEVANCE

The anatomy of the CFL plays an important role in stability of the ankle. Greater recognition of anatomical variation may help improve reconstructive options for patients with chronic lateral ankle instability.

The calcaneofibular ligament groove at the inferior fibula, an ultrasonographic anatomical landmark

PURPOSE

Calcaneofibular ligament (CFL) injuries are harder to diagnose than anterior talofibular ligament (ATFL) ones. This study aimed to clarify the fibular attachment of the CFL and verify the bony landmark for evaluating the CFL on ultrasonography.

METHODS

Fifty-nine ankles were used in this anatomical study. To confirm the control function of the CFL, we performed passive movement manually using cadaveric ankles and observed the ankle positions where the CFLs were tense. Histological observation of CFL attachment of the fibula was performed using Masson's trichrome stain. The ATFL and CFL were removed, and the bone morphology of the CFL attachment and inferior fibular end was imaged using a stereomicroscope and a 3D scanner. Using ultrasonography, we evaluated the bone morphology of the fibular attachment of the CFL in short-axis images of 27 healthy adult ankles.

RESULTS

The CFL was tensed according to ankle motions: supination, maximum dorsi flexion, maximum plantar flexion, and mild plantar flexion-external rotation. Below the CFL attachment of the fibula was a slight groove between the inferior tip and the obscure tubercle of the fibula. This groove was observed in 81.5% of cases using short-axis ultrasonography.

CONCLUSION

The CFL was tensed in various ankle positions to control the movements of the talocrural and subtalar joints. There was a slight groove at the inferior end of the fibula where the CFL coursed downward. We called it the CFL groove and proposed that it could serve as a landmark for the short-axis image of ultrasonography.

Lateral Ankle Ligaments: An Insight Into Their Functional Anatomy, Variations, and Surgical Importance

BACKGROUND

Ankle sprains are prevalent injuries leading to functional impairment. The lateral ankle ligament complex (LLC), comprising the anterior talofibular ligament (ATFL), posterior talofibular ligament (PTFL), and calcaneofibular ligament (CFL), is weak and prone to injury. The morphometric data of these ligaments are essential for orthopedic practices, including techniques like direct repair or ATFL reconstruction with autograft/allograft, which are limited in the literature. The present study aims to document the anatomy and morphometry of the LLC.

METHODS

Fifteen adult Indian-origin embalmed cadavers were selected for the study. Ankles with antemortem or postmortem injuries or previous surgical interventions were excluded from the study. After precise dissection of the ankle's anterior and lateral aspects as per Cunningham's dissection manual, ligaments were exposed. Length and width were measured using a digital vernier caliper. Morphological attributes such as shape, orientation, and inter-fiber angles were documented.

RESULTS

The most common shape in ATFL was a single band (53.33%). Inner ATFL fibers merged with the ankle joint capsule in 73.33%. ATFL mean length and width were 14 ± 2.4 mm and 7.6 ± 2.0 mm. The angle between the fibula's long axis and ATFL fibers was 107 ± 22°, and the angle between tibiotalar joint lines and parallel ATFL fibers was 30 ± 9.5°. A single band of CFL was predominant (73.33%). The mean length and width of CFL were 18.4 ± 3.9 mm and 5.2 ± 1.3 mm; the angle between the anterior fibula border's long axes and parallel CFL line was 131°. PTFL length was 20.9 ± 3.3 mm and width was 6.2 ± 1.4 mm. The mean length and width of the anterior inferior talofibular ligament (AiTFL) were 11.7 ± 2.6 mm and 9.5 ± 1.6 mm, and of the posterior inferior talofibular ligament (PiTFL) were 12.8 ± 2.1 mm and 10.4 ± 2 mm.

CONCLUSION

Comprehensive knowledge of these ligaments' anatomy and relationships is vital for clinical examination and ultrasonography. Understanding LLC details aids radiologists and orthopedic surgeons in graft selection, sizing, and precise anatomical structure placement during surgical reconstruction.

The Distal Fascicle of the Anterior Inferior Tibiofibular Ligament: A Potential Landmark for Lateral Ankle Ligament Reconstruction

BACKGROUND

A reliable landmark and precise distances from the ligament attachments are needed for lateral ankle stabilization surgery. The distal fascicle of the anterior inferior tibiofibular ligament (AITFL) has been used to locate the anterior talofibular ligament (ATFL) or calcaneofibular ligament (CFL) centers on the fibula. However, there is no anatomic study to validate the distal fascicle of the AITFL as a landmark of lateral ankle ligament stabilization, and more importantly, the exact distances from the ATFL or CFL attachments to the distal fascicle of the AITFL are unknown.

METHODS

Sixteen frozen cadaveric specimens (8 paired specimens) with no previous history of ankle injury were used in this study. Whether the distal fascicle of AITFL was present in each specimen was confirmed. Then, the distances from the most distal insertion of the AITFL's distal fascicle to the footprint centers of the ATFL and CFL on the fibula were measured. All measurements were performed by 2 observers, and the intraobserver and interobserver reliabilities were analyzed by intraclass correlation coefficients (ICCs).

RESULTS

The distal fascicle of the AITFL was found in all specimens (100%). The mean distance from the most distal insertion of the AITFL's distal fascicle to the footprint centers of the ATFL, CFL, and the intersection center of the 2 ligaments on the fibula was 6.0 to 7.1 mm, 11.5 to 13.2 mm, and 9.0 to 10.0 mm, respectively. Excellent interobserver and intraobserver agreement (all ICCs > 0.9, P < .01) was shown in the anatomic measurements of these distances.

CONCLUSION

In this cadaveric study, we found that the distal fascicle was a constant structure of the AITFL in the lateral ankle. The distances from the most distal insertion of the AITFL's distal fascicle to the ligamentous footprint centers were reliable and may be used to identify the origins of the ATFL and CFL for lateral ankle ligament reconstruction.

CLINICAL RELEVANCE

This anatomic study validates the AITFL's distal fascicle as a potential landmark and, more importantly, determines the range of distances from AITFL's distal fascicle to the attachment centers of lateral ankle ligaments by anatomic measurements. The data may be used to identify the ATFL and CFL for lateral ankle stabilization surgery and become particularly valuable for endoscopic or arthroscopic techniques.

The ATFL inferior fascicle, the CFL and the PTFL have a continuous footprint at the medial side of the fibula

PURPOSE

Knowledge of the complex anatomy of the lateral ankle ligaments is essential to understand its function, pathophysiology and treatment options. This study aimed to assess the lateral ligaments and their relationships through a 3D view achieved by digitally marking their footprints.

METHODS

Eleven fresh-frozen ankle specimens were dissected. The calcaneus, talus and fibula were separated, maintaining the lateral ligament footprints. Subsequently, each bone was assessed by a light scanner machine. Finally, all the scans were converted to 3D polygonal models. The footprint areas of the talus, calcaneus and fibula were selected, analysed and the surface area was quantified in cm2.

RESULTS

After scanning the bones, the anterior talofibular ligament inferior fascicle (ATFLif), calcaneofibular ligament (CFL) and posterior talofibular ligament (PTFL) footprints were continuous at the medial side of the fibula, corresponding to a continuous footprint with a mean area of 4.8 cm2 (± 0.7). The anterior talofibular ligament (ATFL) footprint on the talus consisted of 2 parts in 9 of the 11 feet, whilst there was a continuous insertion in the other 2 feet. The CFL insertion on the calcaneus was one single footprint in all cases.

CONCLUSION

The tridimensional analysis of the lateral ligaments of the ankle demonstrates that the ATFLif, CFL and PTFL have a continuous footprint at the medial side of the fibula in all analysed specimens. These data can assist the surgeon in interpreting the ligament injuries, improving the imaging assessment and guiding the surgeon to repair and reconstruct the ligaments in an anatomical position.

Evaluation of chronic ankle instability and subtalar instability using the angle between the anterior talofibular ligament and calcaneofibular ligament

PURPOSE

A series of studies have reported a change in the length or thickness of the anterior talofibular (ATFL) and calcaneofibular (CFL) ligaments in patients with chronic ankle instability. However, no study has examined the changes in the angle between the ATFL and CFL in patients diagnosed with chronic ankle instability. Therefore, this study analyzed the change in the angle between the ATFL and CFL in patients diagnosed with chronic ankle instability to confirm its relevance.

METHODS

This retrospective study included 60 patients who had undergone surgery for chronic ankle instability. Stress radiographs comprising the anterior drawer test, varus stress test, Broden's view stress test, and magnetic resonance imaging (MRI) were performed in all patients. The angle between the ATFL and CFL was measured by indicating the vector at the attachment site, as seen on the sagittal plane. Three groups were classified according to the angle between the two ligaments measured by MRI: group I when the angle was > 90°, Group II when the angle was 71-90°, and Group III when the angle was ≤ 70°. The accompanying injuries to the subtalar joint ligament were analyzed via MRI.

RESULTS

A comparison of the angles between the ATFL and CFL measured on MRI in Group I, Group II, and Group III with the angles measured in the operating room revealed a significant correlation. Broden's view stress test revealed a statistically significant difference among the three groups (p < 0.05). The accompanying subtalar joint ligament injuries differed significantly among the three groups (p < 0.05).

CONCLUSION

The ATFL-CFL angle in patients with ankle instability is smaller than the average angle in ordinary people. Therefore, the ATFL-CFL angle might be a reliable and representative measurement tool to assess chronic ankle instability, and subtalar joint instability should be considered if the ATFL-CFL angle is 70° or less.

LEVEL OF EVIDENCE

Level III.

Arthroscopic and Open Procedures Result in Similar Calcaneal Tunnels for Anatomical Reconstruction of Lateral Ankle Ligaments

Purpose

The purpose of this study was to validate the accuracy and reliability of arthroscopic markers of distal insertion of the calcaneofibular ligament (CFL), and to compare the calcaneus bone tunnels of the CFL that were made under arthroscopy and open procedures.

Methods

Fifty-seven patients who underwent lateral ankle ligament reconstruction procedures were enrolled and divided into open (n = 24) and arthroscopic groups (n = 33). Lateral ankle radiography was performed postoperatively, and the calcaneus bone tunnels referenced to several landmarks, including the subtalar joint, calcaneus superior edge, fibular tip, angulation with fibula axis, cross point of the fibular and tangential line of the fibular obscure tubercle cross point of the tangential lines of the talar posterior edge and deepest point of the subtalar joint, and cross point of the fibular axis and perpendicular line across fibular tip. These results were compared between the two groups.

Results

No significant intergroup differences were observed between the parameters. When the bone tunnels of the CFL were referenced to the cross point of tangential lines of the talar posterior edge and deepest point of the subtalar joint, and the cross point of the fibular axis and perpendicular line across fibular tip, the coefficient variations were very high, which indicated that the locations of the bone tunnels were scattered over a large area in both groups.

Conclusions

Arthroscopic and open procedures achieved similar results for calcaneus bone tunnel making of the CFL. However, large variations were observed in both groups.

Level of Evidence

Level III, retrospective cohort study.

Anatomy of the Ankle and Subtalar Joint Ligaments: What We Do Not Know About It?

Understanding of the ankle and subtalar joint ligaments is essential to recognize and manage foot and ankle disorders. The stability of both joints relies on the integrity of its ligaments. The ankle joint is stabilized by the lateral and medial ligamentous complexes while the subtalar joint is stabilized by its extrinsic and intrinsic ligaments. Most injuries to these ligaments are linked with ankle sprains. Inversion or eversion mechanics affect the ligamentous complexes. A profound knowledge of the ligament's anatomy allows orthopedic surgeons to further understand anatomic or nonanatomic reconstructions.

Progress in diagnosis and treatment of acute injury to the anterior talofibular ligament

Injury to the anterior talofibular ligament (ATFL) is a common acute injury of the lateral foot ligament. Untimely and improper treatment significantly affects the quality of life and rehabilitation progress of patients. The purpose of this paper is to review the anatomy and the current methods of diagnosis and treatment of acute injury to the ATFL. The clinical manifestations of acute injury to the ATFL include pain, swelling, and dysfunction. At present, non-surgical treatment is the first choice for acute injury of the ATFL. The standard treatment strategy involves the “peace and love” principle. After initial treatment in the acute phase, personalized rehabilitation training programs can be followed. These may involve proprioception training, muscle training, and functional exercise to restore limb coordination and muscle strength. Static stretching and other techniques to loosen joints, acupuncture, moxibustion massage, and other traditional medical treatments can relieve pain, restore range of motion, and prevent joint stiffness. If the non-surgical treatment is not ideal or fails, surgical treatment is feasible. Currently, arthroscopic anatomical repair or anatomical reconstruction surgery is commonly used in clinical practice. Although open Broström surgery provides good results, the modified arthroscopic Broström surgery has many advantages, such as less trauma, rapid pain relief, rapid postoperative recovery, and fewer complications, and is more popular with patients. In general, when treating acute injury to the ATFL, treatment management and methods should be timely and reasonably arranged according to the specific injury scenario and attention should be paid to the timely combination of multiple therapies to achieve the best treatment results.

Computer-Aided Ankle Ligament Injury Diagnosis from Magnetic Resonance Images Using Machine Learning Techniques

Ankle injuries caused by the Anterior Talofibular Ligament (ATFL) are the most common type of injury. Thus, finding new ways to analyze these injuries through novel technologies is critical for assisting medical diagnosis and, as a result, reducing the subjectivity of this process. As a result, the purpose of this study is to compare the ability of specialists to diagnose lateral tibial tuberosity advancement (LTTA) injury using computer vision analysis on magnetic resonance imaging (MRI). The experiments were carried out on a database obtained from the Vue PACS-Carestream software, which contained 132 images of ATFL and normal (healthy) ankles. Because there were only a few images, image augmentation techniques was used to increase the number of images in the database. Following that, various feature extraction algorithms (GLCM, LBP, and HU invariant moments) and classifiers such as Multi-Layer Perceptron (MLP), Support Vector Machine (SVM), k-Nearest Neighbors (kNN), and Random Forest (RF) were used. Based on the results from this analysis, for cases that lack clear morphologies, the method delivers a hit rate of 85.03% with an increase of 22% over the human expert-based analysis.

Difference in the fibular attachment structure between the superior and inferior fascicles of the anterior talofibular ligament using ultrasonography and histological examinations

PURPOSE

The anterior talofibular ligament (ATFL) is divided into superior (SB) and inferior bands (IB). Although the differences in length and width are known, the structure of the fibular attachment had not been elucidated. The present study aimed to clarify the differences in the fibular attachment structure between ATFL's SB and IB using cross-sectional images along the ligament.

METHODS

An anatomical study using 15 formalin-fixed ankles was performed. The lateral ankle ligament complex was collected after a longitudinal image of SB/IB was visualized by ultrasonography. The specimens were decalcified and sectioned longitudinally at the center of SB/IB using a microtome. Histological evaluation of the enthesis structure at the fibular attachment of SB/IB was performed using hematoxylin-eosin and Masson's trichrome stains.

RESULTS

A fibrillar pattern could not be observed in the longitudinal image at the IB level by ultrasonography. The lengths of ATFL's SB and IB were 20.6 ± 1.6 and 15.3 ± 1.3 mm, respectively, with thicknesses of 1.8 ± 0.4 and 1.0 ± 0.4 mm, respectively. The ATFL's IB was significantly shorter and thinner than the ATFL's SB. The fibular attachment of ATFL's SB had distinct enthesis structure, whereas in the attachment structure of the ATFL's IB, there were several variations including a type with a narrower enthesis structure than the ATFL's SB and a type that merged with or wrapped around the calcaneofibular ligament.

CONCLUSION

The fibular attachment structure between ATFL's SB and IB differs. Our results could be useful information when performing ultrasonography and MRI diagnosis.

Anterior talofibular ligament remnant quality is important for achieving a stable ankle after arthroscopic lateral ankle ligament repair

PURPOSE

The relationship between ligament remnant quality and postoperative outcomes after arthroscopic lateral ankle ligament repair for chronic lateral ankle instability is controversial. This study aimed to determine whether the signal intensity of the anterior talofibular ligament on preoperative magnetic resonance imaging and ligament remnant quality identified on arthroscopy are associated with recurrent ankle instability after arthroscopic lateral ankle ligament repair.

METHODS

A total of 68 ankles from 67 patients with chronic lateral ankle instability who underwent arthroscopic lateral ankle ligament repair were retrospectively studied. The signal intensity of the anterior talofibular ligament was evaluated using T2-weighted magnetic resonance imaging. Arthroscopy was used to evaluate the thickness and mechanical resistance of the anterior talofibular ligament by hook palpation and to classify ankles into two groups: the present anterior talofibular ligament group with adequate mechanical resistance and the absent anterior talofibular ligament group with no mechanical resistance. The outcomes included recurrent ankle instability (respraining of the operated ankle after surgery) and Self-Administered Foot Evaluation Questionnaire scores.

RESULTS

Thirteen ankles were diagnosed with recurrent ankle instability. Patients with a high anterior talofibular ligament T2 signal intensity experienced more recurrent ankle instability than those with a low intensity. As determined via arthroscopy, the absent anterior talofibular ligament group had a higher rate of recurrent ankle instability than the present anterior talofibular ligament group. There were no significant differences in Self-Administered Foot Evaluation Questionnaire scores between patients with high and low anterior talofibular ligament T2 signal intensity, as well as between absent and present anterior talofibular ligament groups based on arthroscopy.

CONCLUSION

Poor quality of the anterior talofibular ligament remnant could result in recurrent ankle instability after arthroscopic lateral ankle ligament repair. Therefore, when treating chronic lateral ankle instability, surgeons should consider ligament quality.

LEVEL OF EVIDENCE

IV.