The in situ force in the calcaneofibular ligament and the contribution of this ligament to ankle joint stability

Plantar flexion with inversion shows highest elastic modulus of calcaneofibular ligament using ultrasound share wave elastography

PURPOSE

The functional role of the calcaneofibular ligament (CFL) is still controversial. We aimed to investigate the anatomical features of the CFL on sonography and the elastic modulus of the CFL in different ankle positions using ultrasound shear-wave elastography (SWE).

METHODS

In 14 cadaveric ankles, the angle of the CFL with respect to the long axis of the fibula was measured in the following ankle positions: neutral (N), 30° plantar flexion (PF), and 20° dorsiflexion (DF). In addition, in 24 ankles of healthy adult volunteers, the elastic modulus of the CFL was evaluated with ultrasound SWE in the following ankle positions: neutral (N), 30° plantar flexion with inversion (PI), 30° plantar flexion with eversion (PE), 20° dorsiflexion with inversion (DI), and 20° dorsiflexion with eversion (DE).

RESULTS

The mean angle of the CFL in N, PF, and DF positions was 139.9° ± 12.7°, 121.3° ± 14.1°, and 158.6° ± 13.1°, respectively. The angle of the CFL in N was significantly greater than that in PF and smaller than that in DF (P < 0.0001, both). The mean elastic modulus of the CFL in the N, PI, PE, DI, and DE positions was: 63.6 ± 50.8, 148.0 ± 39.4, 75.8 ± 40.6, 88.1 ± 31.6, and 61.7 ± 29.4 kPa, respectively. The elastic modulus in PI was significantly higher than in other positions, while the values obtained in DI and DE were also significantly different (P < 0.001, both).

CONCLUSIONS

The angle of the CFL increased with DF. Moreover, ultrasound SWE showed that the CFL was tensed and likely to be injured in the PI position.

Ultrasound-Guided Anterior Talofibular Ligament Repair With Augmentation Can Restore Ankle Kinematics: A Cadaveric Biomechanical Study

Background:

Anterior talofibular ligament (ATFL) repair of the ankle is a common surgical procedure. Ultrasound (US)-guided anchor placement for ATFL repair can be performed anatomically and accurately. However, to our knowledge, no study has investigated ankle kinematics after US-guided ATFL repair.

Hypothesis:

US-guided ATFL repair with and without inferior extensor retinaculum (IER) augmentation will restore ankle kinematics.

Study Design:

Controlled laboratory study; Level of evidence, 4.

Methods:

A 6 degrees of freedom robotic testing system was used to apply multidirectional loads to fresh-frozen cadaveric ankles (N = 9). The following ankle states were evaluated: ATFL intact, ATFL deficient, combined ATFL repair and IER augmentation, and isolated US-guided ATFL repair. Three loading conditions (internal-external rotation torque, anterior-posterior load, and inversion-eversion torque) were applied at 4 ankle positions: 30° of plantarflexion, 15° of plantarflexion, 0° of plantarflexion, and 15° of dorsiflexion. The resulting kinematics were recorded and compared using a 1-way repeated-measures analysis of variance with the Benjamini-Hochberg test.

Results:

Anterior translation in response to an internal rotation torque significantly increased in the ATFL-deficient state compared with the ATFL-intact state at 30° and 15° of plantarflexion (P = .022 and .03, respectively). After the combined US-guided ATFL repair and augmentation, anterior translation was reduced significantly compared with the ATFL-deficient state at 30° and 15° of plantarflexion (P = .0012 and .005, respectively). Anterior translation was not significantly different for the isolated ATFL-repair state compared with the ATFL-deficient or ATFL-intact states at 30° and 15° of plantarflexion.

Conclusion:

Combined US-guided ATFL repair with augmentation of the IER reduced lateral ankle laxity due to ATFL deficiency. Isolated US-guided ATFL repair did not reduce laxity due to ATFL deficiency, nor did it increase instability compared with the intact ankle.

Clinical Relevance:

US-guided ATFL repair with IER augmentation is a minimally-invasive technique to reduce lateral ankle laxity due to ATFL deficiency. Isolated US-guided ATFL repair may be a viable option if accompanied by a period of immobilization.

Effects of the Ankle Flexion Angle During Anterior Talofibular Ligament Reconstruction on Ankle Kinematics, Laxity, and In Situ Forces of the Reconstructed Graft

BACKGROUND

This study aimed to evaluate the effects of the ankle flexion angle during anterior talofibular ligament (ATFL) reconstruction on ankle kinematics, laxity, and in situ force of a graft.

METHODS

Twelve cadaveric ankles were evaluated using a 6-degrees of freedom robotic system to apply passive plantar flexion and dorsiflexion motions and multidirectional loads. A repeated measures experiment was designed using the intact ATFL, transected ATFL, and reconstructed ATFL. During ATFL reconstruction (ATFLR), the graft was fixed at a neutral position (ATFLR 0 degrees), 15 degrees of plantar flexion (ATFLR PF15 degrees), and 30 degrees of plantar flexion (ATFLR PF30 degrees) with a constant initial tension of 10 N. The 3-dimensional path and reconstructed graft tension were simultaneously recorded, and the in situ force of the ATFL and reconstructed grafts were calculated using the principle of superposition.

RESULTS

The in situ forces of the reconstructed grafts in ATFLR 0 degrees and ATFLR PF 15 degrees were significantly higher than those of intact ankles. The ankle kinematics and laxity produced by ATFLR PF 30 degrees were not significantly different from those of intact ankles. The in situ force on the ATFL was 19.0 N at 30 degrees of plantar flexion. In situ forces of 41.0, 33.7, and 21.9 N were observed at 30 degrees of plantar flexion in ATFLR 0, 15, and 30 degrees, respectively.

CONCLUSION

ATFL reconstruction with the peroneus longus (PL) tendon was performed with the graft at 30 degrees of plantar flexion resulted in ankle kinematics, laxity, and in situ forces similar to those of intact ankles. ATFL reconstructions performed with the graft fixed at 0 and 15 degrees of the plantar flexion resulted in higher in situ forces on the reconstructed graft.

CLINICAL RELEVANCE

Fixing the ATFL tendon graft at 30 degrees of plantar flexion results in an in situ force closest to that of an intact ankle and avoids the excessive tension on the reconstructed graft.

Characteristics and predictors of muscle strength deficit in mechanical ankle instability

Purpose

Muscle strength training is a common strategy for treating chronic ankle instability (CAI), but the effectiveness decreases for mechanical ankle instability (MAI) patients with initial severe ligament injuries. The purpose of this study was to investigate the characteristics and the potential predictors of muscle strength deficit in MAI patients, with a view to proposing a more targeted muscle strength training strategy.

Methods

A total of 220 MAI patients with confirmed initial lateral ankle ligament rupture and a postinjury duration of more than 6 months were included. All patients underwent a Biodex isokinetic examination of the ankle joints of both the affected and unaffected sides. Then, the associations between the limb symmetry index (LSI) (mean peak torque of the injury side divided by that of the healthy side) and the patients’ sex, body mass index, postinjury duration, presence of intra-articular osteochondral lesions, presence of osteophytes and ligament injury pattern (i.e., isolated anterior talofibular ligament (ATFL) injury or combined with calcaneofibular ligament injury) were analysed.

Results

There was significantly weaker muscle strength on the affected side than on the unaffected side in all directions (p < 0.05). The LSI in plantar flexion was significantly lower than that in dorsiflexion at 60°/s (0.87 vs 0.98, p < 0.001). A lower LSI in eversion was significantly correlated with female sex (0.82 vs 0.94, p = 0.016) and isolated ATFL injury (0.86 vs 0.95, p = 0.012). No other factors were found to be associated with muscle strength deficits.

Conclusion

MAI patients showed significant muscle strength deficits on the affected side, especially in plantar flexion. There were greater strength deficits in eversion in females and individuals with an isolated ATFL injury. Thus, a muscle strength training programme for MAI patients was proposed that focused more on plantar flexion training and eversion training for females and those with an isolated ATFL injury.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03754-9.

Open Brostrom for Lateral Ligament Stabilization

PURPOSE OF REVIEW

Lateral ankle ligament sprains are one of the most commonly reported injuries in high-level athletes and the general population. Unfortunately, up to 40% of these can go on to develop chronic lateral ankle instability which in the right circumstances requires surgical intervention. The purpose of this review is to present the gold standard surgical treatment for chronic lateral instability with anatomic ligament repair and to highlight the techniques, outcomes, and importance of anatomy when considering surgical treatment.

RECENT FINDINGS

Recent and remote literature agrees that the initial treatment for chronic ankle instability is non-operative rehabilitation. In the cases where this fails, the gold standard of surgical treatment is open anatomic repair using the Brostrom-Gould technique which stands out as having very good results over the course of time. Recent studies have shown equally good outcomes with arthroscopy as well as with internal brace devices, and both techniques show potential for earlier rehabilitation. In those with contraindications for anatomic repair including innate soft tissue laxity, high BMI, and in the revision setting, anatomic ligament reconstruction is an appropriate surgical option. Open modified Brostrom lateral ligament repair continues to be the preferred method of surgical treatment for chronic lateral ligament instability. In the setting of new modifications and techniques, long-term outcome studies are necessary to identify both their usefulness in long term and to compare them to the open surgery outcomes. It would be useful to standardize rehabilitation protocols as well as return to sport metrics in order to better evaluate outcomes moving forward.

Effect of Initial Graft Tension During Anterior Talofibular Ligament Reconstruction on Ankle Kinematics, Laxity, and In Situ Forces of the Reconstructed Graft

BACKGROUND

Although a variety of surgical procedures for anterior talofibular ligament (ATFL) reconstruction have been reported, the effect of initial graft tension during ATFL reconstruction remains unclear.

PURPOSE/HYPOTHESIS

This study investigated the effects of initial graft tension on ATFL reconstruction. We hypothesized that a high degree of initial graft tension would cause abnormal kinematics and laxity.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve cadaveric ankles were tested with a robotic system with 6 degrees of freedom to apply passive plantarflexion and dorsiflexion motions and a multidirectional load. A repeated measures experiment was designed with the intact ATFL, transected ATFL, and reconstructed ATFL at initial tension conditions of 10, 30, 50, and 70 N. The 3-dimensional path and reconstructed graft tension were simultaneously recorded, and the in situ forces of the ATFL and reconstructed graft were calculated with the principle of superposition.

RESULTS

Initial tension of 10 N was sufficient to imitate normal ankle kinematics and laxity, which were not significantly different when compared with those of the intact ankles. The in situ force on the reconstructed graft tended to increase as the initial tension increased. In situ force on the reconstructed graft >30 N was significantly greater than that of intact ankles. The in situ force on the ATFL was 19 N at 30° of plantarflexion. In situ forces of 21.9, 30.4, 38.2, and 46.8 N were observed at initial tensions of 10, 30, 50, and 70 N, respectively, at 30° of plantarflexion.

CONCLUSION

Approximate ankle kinematic patterns and sufficient laxity, even with an initial tension of 10 N, could be obtained immediately after ATFL reconstruction. Moreover, excessive initial graft tension during ATFL reconstruction caused excessive in situ force on the reconstructed graft.

CLINICAL RELEVANCE

This study revealed the effects of initial graft tension during ATFL reconstruction. These data suggest that excessive tension during ATFL reconstruction should be avoided to ensure restoration of normal ankle motion.

Repair of only anterior talofibular ligament resulted in similar outcomes to those of repair of both anterior talofibular and calcaneofibular ligaments

PURPOSE

To compare the surgical outcomes of the two different ankle stabilization techniques.

METHODS

This randomized controlled trial aimed to compare the outcomes of the modified Broström procedure with [calcaneofibular ligament (CFL) group] or without CFL repair [anterior talofibular ligament (ATFL) only group]. Of the 50 patients randomly assigned to two groups, 43 were followed up prospectively for ≥ 2 years (CFL group: 22 patients, 36.6 ± 13.1 months; ATFL Only group: 21 patients, 35.3 ± 11.9 months). Functional outcomes were assessed using the Karlsson-Peterson and Tegner activity level scoring systems. Anterior talar translation (ATT), talar tilt angle (TTA), and degrees of displacement of the calcaneus against the talus on stress radiographs were measured. All parameters were compared between the two groups. Multiple regression analysis setting the postoperative Karlsson-Peterson score as the dependent variable was performed to determine the significant variable.

RESULTS

There were no significant differences between the two groups in functional (Karlsson-Peterson and Tegner activity level) scores at the last follow-up and their changes. There were no significant differences between the two groups in the ATT, TTA, their differences compared with the contralateral ankles, and degrees of displacement of the calcaneus against the talus at the last follow-up. Osteochondral lesion of the talus rather than CFL repair was the significant variable related to functional outcome.

CONCLUSION

The modified Broström procedure with additional CFL repair did not result in a significant advantage in any measured outcome at 3 years.

LEVEL OF EVIDENCE

Randomized controlled trial, Level I.

Function of ankle ligaments for subtalar and talocrural joint stability during an inversion movement - an in vitro study

Background

The lateral ankle ligament complex consisting of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL) and the posterior talofibular ligament (PTFL) is known to provide stability against ankle joint inversion. As injuries of the ankle joint have been reported at a wide range of plantarflexion/dorsiflexion angles, the aim of the present study was to evaluate the stabilizing function of these ligaments depending on the sagittal plane positioning of the ankle joint.

Methods

Eight fresh-frozen specimens were tested on a custom-built ankle deflection tester allowing the application of inversion torques in various plantarflexion/dorsiflexion positions. A motion capture system recorded kinematic data from the talus, calcaneus and fibula with bone-pin markers during inversion movements at 10° of dorsiflexion, at neutral position and at plantarflexion 10°. ATFL, CFL and PTFL were separately but sequentially sectioned in order to assess the contribution of the individual ligament with regard to ankle joint stability.

Results

Joint- and position-specific modulations could be observed when the ligaments were cut. Cutting the ATFL did not lead to any observable alterations in ankle inversion angle at a given torque. But subsequently cutting the CFL increased the inversion angle of the talocrural joint in the 10° plantarflexed position, and significantly increased the inversion angle of the subtalar joint in the 10° dorsiflexed position. Sectioning of the PTFL led to minor increases of inversion angles in both joints.

Conclusions

The CFL is the primary ligamentous stabilizer of the ankle joint against a forced inversion. Its functioning depends greatly on the plantar−/dorsiflexion position of the ankle joint complex, as it provides the stability of the talocrural joint primarily during plantarflexion and the stability of the subtalar joint primarily during dorsiflexion.

Electronic supplementary material

The online version of this article (10.1186/s13047-019-0330-5) contains supplementary material, which is available to authorized users.

Kinematics and Laxity of the Ankle Joint in Anatomic and Nonanatomic Anterior Talofibular Ligament Repair: A Biomechanical Cadaveric Study

BACKGROUND

Although it is crucial to accurately identify the anterior talofibular ligament (ATFL) attachment site, it may not be feasible to fully observe the ATFL attachment site during arthroscopic surgery. As a result, the repair position might often be an unintentionally nonanatomic ATFL attachment site.

HYPOTHESIS

Anatomic ATFL repair restores kinematics and laxity to the ankle joint, while nonanatomic ATFL repair does not.

STUDY DESIGN

Controlled laboratory study.

METHODS

Seven normal fresh-frozen human cadaveric ankles were used. The ankles were tested with a 6 degrees of freedom robotic system. The following ankle states were evaluated: intact, ATFL injured, ATFL anatomic repair, and ATFL nonanatomic repair. The ATFL nonanatomic repair position was set 8 mm proximal from the center of the ATFL attachment site of the fibula. For each state, a passive plantarflexion (PF)-dorsiflexion (DF) kinematics test and a multidirectional loading test (anterior forces, inversion moment, and internal rotation moment) were performed.

RESULTS

The kinematics and laxity of the anatomic repair were not significantly different from those of the intact state. In nonanatomic repair, the inversion-eversion angle showed significant inversion (3.0°-3.4°) from 5° to 15° of DF, and the internal rotation-external rotation angle showed significant internal rotation (2.0°) at neutral PF-DF versus the intact state. In addition, internal rotation laxity was significantly increased (5.5°-5.8°) relative to the intact state in the nonanatomic repair at 30° and 15° of PF. There were no significant differences in anterior-posterior translation between the repairs.

CONCLUSION

Although the anatomic ATFL repair state did not show significant differences in kinematics and laxity relative to the intact state, the nonanatomic ATFL repair state demonstrated significant inversion and internal rotation kinematics and internal rotation laxity when compared with the intact state.

CLINICAL RELEVANCE

Nonanatomic repair alters kinematics and laxity from the intact condition.

Development and validation of a robotic system for ankle joint testing

Ankle sprains are the most common sports injury. Gaining a better understanding of ankle mechanics will help improve current treatments, enabling a better quality of life for patients following surgery. In this paper, the development of a robotic system for ankle joint testing is presented. It is composed of an industrial robot, a universal force/torque sensor and bespoke holders allowing high repositioning of specimens. A specimen preparation protocol that uses optical tracking to register the ankle specimens is used. A registration technique is applied to define and calibrate the task related coordinate system needed to control the joint's degrees of freedom and to simulate standardised, clinical ankle laxity tests. Experiments were carried out at different flexion angles using the robotic platform. Optical tracking was used to record the resulting motion of the tibia for every simulated test. The measurements from the optical tracker and the robot were compared and used to validate the system. These findings showed that the optical tracking measurements validate those from the robot for ankle joint testing with interclass coefficients equal to 0.991, 0.996 and 0.999 for the anterior-posterior translations, internal-external and inversion-eversion rotations.

Effect of Initial Graft Tension During Calcaneofibular Ligament Reconstruction on Ankle Kinematics and Laxity

BACKGROUND

Although a variety of surgical procedures for lateral ankle ligament reconstruction have frequently been reported, little is known about the effects of initial graft tension. Purpose/Hypothesis: The purpose was to investigate the effects of initial graft tension in calcaneofibular ligament (CFL) reconstruction. It was hypothesized that a high degree of initial graft tension would cause abnormal kinematics, laxity, and excessive graft tension.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve cadaveric ankles were tested with a 6 degrees of freedom robotic system to apply passive plantarflexion-dorsiflexion motion and multidirectional loads. A repeated-measures experiment was designed with the CFL intact, CFL transected, and CFL reconstructed with 4 initial tension conditions (10, 30, 50, and 70 N). The 3-dimensional path and reconstructed graft tension were simultaneously recorded.

RESULTS

The calcaneus in CFL reconstruction with an initial tension of 70 N had the most eversion relative to the intact condition (mean eversion translations of 1.2, 3.0, 5.0, and 6.2 mm were observed at initial tensions of 10, 30, 50, and 70 N, respectively). The calcaneus also moved more posteriorly with external rotation as the initial tension increased. The reconstructed graft tension tended to increase as the initial tension increased.

CONCLUSION

Ankle kinematic patterns and laxity after CFL reconstruction tended to become more abnormal as the initial graft tension increased at the time of surgery. Moreover, excessive initial graft tension caused excessive tension on the reconstructed graft.

CLINICAL RELEVANCE

This study indicated the importance of initial graft tension during CFL reconstruction. Overtensioning during CFL reconstruction should be avoided to imitate a normal ankle.

ACL Function in Bicruciate-Retaining Total Knee Arthroplasty

BACKGROUND

Bicruciate-retaining total knee arthroplasty (BCR-TKA) is attracting attention because of the functional and satisfaction outcomes associated with keeping the anterior cruciate ligament (ACL) intact. However, knowledge of the functional importance of the ACL after BCR-TKA is limited. We performed a biomechanical investigation of ACL function following BCR-TKA compared with that in the intact knee.

METHODS

We investigated 8 fresh-frozen human cadaveric knees using a 6-degrees-of-freedom robotic system that allowed natural joint motion. Three knee states-intact knee, BCR-TKA, and BCR-TKA with ACL transection (BCR-TKA + ACLT)-were evaluated. For each knee state, the kinematics during passive flexion-extension motion (from 0° to 120°) and anteroposterior laxity at 0°, 15°, 30°, 60°, and 90° of flexion in response to a 100-N load were investigated. The recorded knee motions of the intact and BCR-TKA knees during each test were repeated after ACLT to calculate the ACL in situ force.

RESULTS

The femur in the BCR-TKA group translated posteriorly and rotated externally during passive knee flexion and was in an anterior position compared with the femur in the intact-knee state. After ACLT, the femur translated posteriorly, compared with the BCR-TKA group, at 0° and 10° (p < 0.05). The anteroposterior laxities of the BCR-TKA and intact knees were comparable at all flexion angles and increased 2-fold or more after ACLT (p < 0.01). The ACL in situ force in the BCR-TKA knees was 2-fold to 6-fold higher than that in the intact knees at 0°, 15°, 90°, and 120° during a passive path (p < 0.05) and equivalent to that in the intact knees under anterior loading.

CONCLUSIONS

The preserved ACL in the BCR-TKA knees was functional, like the ACL in the intact knees, under anterior tibial loading and contributed to good anteroposterior stability. However, the kinematics and ACL in situ force differed between the intact and BCR-TKA knees during passive flexion-extension movements.

CLINICAL RELEVANCE

Surgeons may not be able to prevent overtensioning of the ACL during a standardized BCR-TKA procedure, which could potentially limit range of motion.