Radiographic monitoring of the distal insertion of the calcaneofibular ligament in anatomical reconstructions of ankle instabilities: A preliminary cadaveric study

Accuracy of Cutaneous Landmarks Compared to Ultrasound to Locate the Calcaneal Footprint of the CFL

The purpose was to determine the accuracy of the techniques of Lopes et al. and Michels et al., compared to ultrasound, to locate the center of the calcaneal footprint of the CFL in healthy volunteers. The authors recruited 17 healthy adult volunteers at 1 center with no current ankle pathologies and no previous surgical antecedents on either ankle. The authors recorded the age, sex, height, BMI, and ankle side for each volunteer. Measurements were made on both ankles of the 17 volunteers to increase the sample size and ensure less dispersion of data, independently by 2 surgeons: 1 senior surgeon with 15 years' experience and 1 junior with 3 years' experience. The location of the center of the calcaneal footprint of the CFL was determined by each surgeon using 3 methods: (1) the cutaneous technique of Lopes et al., (2) the cutaneous technique of Michels et al., and (3) ultrasound imaging. The 17 volunteers (34 feet) had a mean age of 26.3 ± 8.7 and a BMI of 21.7 ± 2.9. The Michels point was significantly closer (4.6 ± 3.7 mm) than the Lopes point (11.1 ± 5.4 mm) to the true center of the calcaneal footprint of the CFL determined by ultrasound, notably in the vertical direction. The Michels point was located significantly closer to the true center of the calcaneal footprint of the CFL and demonstrated less dispersion than the Lopes point, indicated by significantly lower absolute mean deviation from the true center of the calcaneal footprint of the CFL, and that ultrasound is therefore preferred to locate the footprint the CFL.

Radiographic Anatomy of the Lateral Ankle Ligament Complex: A Cadaveric Study

BACKGROUND

When lateral ankle sprains progress into chronic lateral ankle instability (CLAI), restoring precise anatomic relationships of the lateral ankle ligament complex (LALC) surgically is complex. This study quantifies the radiographic relationships between the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and prominent osseous landmarks visible under fluoroscopy to assist in perioperative practices for minimally invasive surgery for CLAI.

METHODS

Ten fresh frozen ankle specimens were dissected to expose the LALC and prepared by threading a radiopaque filament through the ligamentous footprints of the ATFL and CFL. Fluoroscopic images were digitally analyzed to define dimensional characteristics of the ATFL and CFL. Directional measurements of the ligamentous footprints relative to the lateral process of the talus and the apex of the posterior facet of the calcaneus were calculated.

RESULTS

Dimensional measurements of the ATFL were a mean length of 9.3 mm, fibular footprint of 9.4 mm, and talar footprint of 9.1 mm. Dimensional measurements of the CFL were a mean length of 19.4 mm, fibular footprint of 8.2 mm, and calcaneal footprint of 7.3 mm. From the radiographic apparent tip of the lateral process of the talus, the fibular attachment of the ATFL was found 13.3 mm superior and 4.4 mm posterior, whereas the talar attachment was found 11.5 mm superior and 4.8 mm anterior. From the radiographic apparent posterior apex of the posterior facet of the calcaneus, the fibular attachment of the CFL was found 0.2 mm inferior and 6.8 mm anterior, whereas the calcaneal attachment was found 14.3 mm inferior and 5.9 mm posterior.

CONCLUSION

The ATFL and CFL were radiographically analyzed using radiopaque filaments to outline the ligamentous footprints in their native locations. These ligaments were also localized with reference to 2 prominent osseous landmarks. These findings may assist in perioperative practices for keyhole incision placement and arthroscopic guidance. Perfect lateral ankle joint imaging with talar domes superimposed is required to be able to do this.

CLINICAL RELEVANCE

Radiographic evaluation of the ATFL and CFL with reference to prominent osseous landmarks identified under fluoroscopy may assist in perioperative practices for minimally invasive surgery to address CLAI for keyhole incision placement and arthroscopic guidance.

Advantages of ultrasound identification of the distal insertion of the calcaneofibular ligament during ligament reconstructions

INTRODUCTION

In lateral ankle instability, anatomical ligament reconstructions are generally performed using arthroscopy. The ligament graft is passed through the talar, fibular and calcaneal tunnels, reconstructing the anterior talofibular and calcaneofibular (CFL) bundles. However, the calcaneal insertion of the CFL needs to be performed in an extra-articular fashion, and cannot be carried out under arthroscopy, thus requiring specific anatomical landmarks. For obtaining these landmarks, methods based on radiography or surface anatomy have already been described but can only offer an approximate identification of the actual CFL anatomical insertion point. In contrast, an ultrasound technique allows direct visualization of the insertion point and of the sural nerve that may be injured during surgery. Our study aimed to assess the reliability and accuracy of ultrasound visualization when performing calcaneal insertion of the CFL with specific monitoring of the sural nerve.

MATERIALS AND METHODS

Our anatomical study was carried out on 15 ankles available from a body donation program. Ultrasound identification of the sural nerve was obtained first with injection of dye. A needle was positioned at the level of the calcaneal insertion of the CFL. After dissection, in all the ankles, the dye was in contact with the sural nerve and the needle was located in the calcaneal insertion area of the CFL. The mean distance between the sural nerve and the needle was 4.8 mm (range 3-7 mm).

DISCUSSION AND CONCLUSION

A pre- or intra-operative ultrasound technique is a simple and reliable means for obtaining anatomical landmarks when drilling the calcaneal tunnel for ligament reconstruction of the lateral plane of the ankle. This tunnel should preferably be drilled obliquely from the heel towards the subtalar joint (1 h-3 h direction on an ultrasound cross section), which preserves a maximum distance from the sural nerve for safety purposes, while allowing an accurate anatomical positioning of the osseous tunnel.

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.

Accuracy of radiographic techniques in detection of the calcaneofibular ligament calcaneal insertion for lateral ankle ligament complex surgery

BACKGROUND

Grade III ankle sprains that fail conservative treatment can require surgical management. Anatomic procedures have been shown to properly restore joint mechanics, and precise localization of insertion sites of the lateral ankle complex ligaments can be determined through radiographic techniques. Ideally, radiographic techniques that are easily reproducible intraoperatively will lead to a consistently well-placed CFL reconstruction in lateral ankle ligament surgery.

PURPOSE

To determine the most accurate method to locate the calcaneofibular ligament (CFL) insertion radiographically.

METHODS

MRIs of 25 ankles were utilized to identify the "true" insertion of the CFL. Distances between the true insertion and three bony landmarks were measured. Three proposed methods (Best, Lopes, and Taser) for determining the CFL insertion were applied to lateral ankle radiographs. X and Y coordinate distances were measured from the insertion found on each proposed method to the three bony landmarks: the most superior point of the postero-superior surface of the calcaneus, the posterior most aspect of the sinus tarsi, and the distal tip of the fibula. X and Y distances were compared to the true insertion found on MRI. All measurements were made using a picture archiving and communication system. The average, standard deviation, minimum, and maximum were obtained. Statistical analysis was performed using repeated measures ANOVA, and a post hoc analysis was performed with the Bonferroni test.

RESULTS

The Best and Taser techniques were found to be closest to the true CFL insertion when combining X and Y distances. For distance in the X direction, there was no significant difference between techniques (P = 0.264). For distance in the Y direction, there was a significant difference between techniques (P = 0.015). For distance in the combined XY direction, there was a significant difference between techniques (P = 0.001). The CFL insertion as determined by the Best method was significantly closer to the true insertion compared to the Lopes method in the Y (P = 0.042) and XY (P = 0.004) directions. The CFL insertion as determined by the Taser method was significantly closer to the true insertion compared to the Lopes method in the XY direction (P = 0.017). There was no significant difference between the Best and Taser methods.

CONCLUSION

If the Best and Taser techniques can be readily used in the operating room, they would likely prove the most reliable for finding the true CFL insertion.

A calcaneal tunnel for CFL reconstruction should be directed to the posterior inferior medial edge of the calcaneal tuberosity

PURPOSE

Anatomical reconstruction of the calcaneofibular ligament (CFL) is a common technique to treat chronic lateral ankle instability. A bone tunnel is used to fix the graft in the calcaneus. The purpose of this study is to provide some recommendations about tunnel entrance and tunnel direction based on anatomical landmarks.

METHODS

The study consisted of two parts. The first part assessed the lateral tunnel entrance for location and safety. The second part addressed the tunnel direction and safety upon exiting the calcaneum on the medial side. In the first part, 29 specimens were used to locate the anatomical insertion of the CFL based on the intersection of two lines related to the fibular axis and specific landmarks on the lateral malleolus. In the second part, 22 specimens were dissected to determine the position of the neurovascular structures at risk during tunnel drilling. Therefore, a method based on four imaginary squares using external anatomical landmarks was developed.

RESULTS

For the tunnel entrance on the lateral side, the mean distance to the centre of the CFL footprint was 2.8 ± 3.0 mm (0-10.4 mm). The mean distance between both observers was 4.2 ± 3.2 mm (0-10.3 mm). The mean distance to the sural nerve was 1.4 ± 2 mm (0-5.8 mm). The mean distance to the peroneal tendons was 7.3 ± 3.1 mm (1.2-12.4 mm). For the tunnel exit on the medial side, the two anterior squares always contained the neurovascular bundle. A safe zone without important neurovascular structures was found and corresponded to the two posterior squares.

CONCLUSION

Lateral landmarks enabled to locate the CFL footprint. Precautions should be taken to protect the nearby sural nerve. A safe zone on the medial side could be determined to guide safe tunnel direction. A calcaneal tunnel should be directed to the posterior inferior medial edge of the calcaneal tuberosity.

Prediction of suspicious ankle instability using the calcaneofibular ligament cross-sectional area

Background

An injured calcaneofibular ligament (CFL) is a major cause of ankle instability (AI). Previous research has demonstrated that the thickness of the calcaneofibular ligament (CFLT) is correlated with higher-grade sprains and ankle instability. However, inflammatory hypertrophy is distinct from ligament thickness; accordingly, we considered that the calcaneofibular ligament cross-sectional area (CFLCSA) as a potential morphological parameter to analyze inflammatory CFL. We hypothesized that the CFLCSA was a key morphologic parameter in AI diagnosis.

Methods

We gathered the CFL data of 26 AI patients and 25 control subjects who had undergone ankle magnetic resonance imaging (A-MRI), and it had revealed no evidence of AI. Ankle level T1-weighted coronal A-MRI images were acquired. Using our image analysis program (INFINITT PACS), we analyzed the CFLT and CFLCSA at the CFL on the A-MRI. The CFLCSA was measured as the whole ligament cross-sectional area of the CFL that was most hypertrophied in the transverse A-MR images. The CFLT was measured at the thickest level of CFL.

Results

The mean CFLT was 3.49±0.82 mm in the control group, and 4.82±0.76 mm in the AI group. The mean CFLCSA was 33.31±7.02 mm² in the control group, and 65.33±20.91 mm² in the AI group. The AI patients had significantly greater CFLT (P<0.001) and CFLCSA (P<0.001) than the control group participants. A receiver operating characteristic (ROC) curve analysis in the evaluation of the diagnostic tests showed that the optimal cut-off score of the CFLT was 4.06 mm, with 76.9% sensitivity, 76.0% specificity, and an area under the curve (AUC) of 0.89 (95% CI, 0.79-0.99). The optimal cut-off threshold of the CFLCSA was 43.85 mm², with 92.3% sensitivity, 92.0% specificity, and AUC of 0.94 (95% CI, 0.86-1.00).

Conclusions

Even though the CFLT and CFLCSA were both significantly associated with AI, the CFLCSA was a more sensitive diagnostic test.

No Difference between Percutaneous and Arthroscopic Techniques in Identifying the Calcaneal Insertion during Ankle Lateral Ligament Reconstruction: A Cadaveric Study

Background. Both percutaneous and arthroscopic techniques have been introduced in anatomic ankle lateral ligaments reconstruction. The purpose of this study was to compare these two techniques in identifying the calcaneal insertion of the calcaneofibular ligament (CFL). Methods. Fifteen fresh-frozen human ankle cadaver specimens were used in this study. Each specimen was tested in three stages. For stage 1, each specimen was evaluated under arthroscopy. After debridement was performed, the insertion of the CFL on the calcaneus was identified, and a 1.5mm Kirschner wire was drilled at the center of the insertion. For stage 2, a percutaneous technique was used to identify the center of the insertion of the CFL. A second 1.5 mm Kirschner wire was drilled through the skin marker. For stage 3, the ankle was dissected, the footprint of the CFL was identified under direct vision, and the distances between the center of the CFL insertion on the calcaneus and the two Kirschner wires were measured, respectively. Results. In the arthroscopic technique group, the mean distance from the Kirschner wire to the center of the CFL insertion in the calcaneus was 3.4 ± 1.3 mm. In the percutaneous technique group, the mean distance from the Kirschner wire to the center of the CFL insertion was 3.2 ± 1.4 mm. No significant difference was found between the two groups. Conclusion. No difference in identifying the calcaneal insertion of the CFL was found between the percutaneous and the arthroscopic ankle lateral ligaments reconstruction technique. Both techniques can be used during anatomic ligaments reconstruction in treatment of chronic ankle instability.

Three-Dimensional computed tomography tunnel assessment of allograft anatomic reconstruction in chronic ankle instability: 33 cases

INTRODUCTION

Although clinical results of anatomic reconstruction using allograft are reportedly good, studies on how accurately the tunnel has been made after surgery are very rare. The purpose of this study was to analyze the postoperative locations of the tunnels through 3-dimensional computed tomography (3D-CT) after anatomic ligament reconstruction and to evaluate its clinical results.

HYPOTHESIS

We hypothesized that anatomic lateral ligament reconstruction could lead to excellent results in clinical outcomes by repositioning anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) accurately.

MATERIALS AND METHODS

Thirty-three special forces of soldiers who were diagnosed as chronic ankle instability (CAI) were included. Visual analogue scale (VAS), American orthopaedic foot and ankle society (AOFAS) ankle-hind foot functional scores, and Tegner activity scale were comparatively analyzed before the surgery and at final follow-up. The locations of the talar, fibular and calcaneal tunnels were evaluated with 3D-CT taken after the surgery. Talar tilt and anterior drawer displacement were measured on stress radiographs.

RESULTS

The mean follow-up period was 26.8±3.6 months. The VAS decreased from 6.9±1.6 to 1.7±1.3, AOFAS ankle-hindfoot functional score increased from 61.3±14.8 to 88.7±9.2, and Tegner activity scale improved from 5.3±1.2 to 6.4±1.3 (p<0.001). Talar tunnel for ATFL was located about68% of the way from the lateral talar process, and fibular tunnels for ATFL and CFL were approximately 52% and 20% of the way from the fibular tip. The calcaneus tunnel was approximately 17mm posterosuperior from the peroneal tubercle on 3D-CT. Talar tilt decreased from 15.8±4.8 to 3.9±2.1 degrees (p<0.001). There were excellent inter-observer agreements for CT evaluation (Kappa values were from 0.83 to 0.92). There was no relapse of lateral instability.

DISCUSSION

Anatomic reconstruction of the lateral ligaments using allograft and the interference screw for CAI showed good results in postoperative stability and subjective clinical evaluation by repositioning the location of ATFL and CFL accurately on radiological determination.

LEVEL OF EVIDENCE

IV, Case-series.

Anatomic validation of the lateral malleolus as a cutaneous marker for the distal insertion of the calcaneofibular ligament

PURPOSE

An anatomic study was performed to confirm whether the lateral malleolus could serve as a simple and reproducible anatomic reference for the distal insertion of the calcaneofibular ligament (CFL).

METHODS

Dissection was performed after placement of a Kirschner wire to simulate the calcaneal tunnel for the distal insertion of the CFL. The skin was penetrated 1 cm distal and posterior to the tip of the lateral malleolus. The main information recorded was the distance from the Kirschner wire to the centre of the distal insertion of the CFL. Other elements were noted (characteristics of the CFL, distance between the distal insertion of the CFL-peroneal tubercle, nerve or tendon injuries).

RESULTS

Thirty ankles were dissected. The mean distance from the Kirschner wire to the centre of the distal insertion of the CFL was 2.4 ± 1.8 mm. Only one case of peroneal injury was noted. The sural nerve was usually located a mean 1.8 ± 1.1 mm from the Kirschner wire. The posterior tibial vascular pedicle was a mean 27.8 ± 3.5 mm from the point of exit of the Kirschner wire.

CONCLUSION

Using the lateral malleolus as the cutaneous reference for the distal insertion of the CFL seems to be more reliable than the pure arthroscopic technique. This study describes a percutaneous technique to obtain a calcaneal tunnel for distal insertion of the CFL. The sural nerve is at the greatest risk of injury with this technique and requires careful subcutaneous incision to prevent injury. This new percutaneous technique is less invasive than a purely arthroscopic technique and more accurately identifies the location of the tunnel. It can be used to do calcaneal tunnel in clinical practice during anatomic ligament reconstruction for chronic ankle instability.