The role of ankle ligaments and articular geometry in stabilizing the ankle

Investigation into the effect of deltoid ligament injury on rotational ankle instability using a three-dimensional ankle finite element model

Background

Injury to the lateral collateral ligament of the ankle may cause ankle instability and, when combined with deltoid ligament (DL) injury, may lead to a more complex situation known as rotational ankle instability (RAI). It is unclear how DL rupture interferes with the mechanical function of an ankle joint with RAI.

Purpose

To study the influence of DL injury on the biomechanical function of the ankle joint.

Methods

A comprehensive finite element model of an ankle joint, incorporating detailed ligaments, was developed from MRI scans of an adult female. A range of ligament injury scenarios were simulated in the ankle joint model, which was then subjected to a static standing load of 300 N and a 1.5 Nm internal and external rotation torque. The analysis focused on comparing the distribution and peak values of von Mises stress in the articular cartilages of both the tibia and talus and measuring the talus rotation angle and contact area of the talocrural joint.

Results

The dimensions and location of insertion points of ligaments in the finite element ankle model were adopted from previous anatomical research and dissection studies. The anterior drawer distance in the finite element model was within 6.5% of the anatomical range, and the talus tilt angle was within 3% of anatomical results. During static standing, a combined rupture of the anterior talofibular ligament (ATFL) and anterior tibiotalar ligament (ATTL) generates new stress concentrations on the talus cartilage, which markedly increases the joint contact area and stress on the cartilage. During static standing with external rotation, the anterior talofibular ligament and anterior tibiotalar ligament ruptured the ankle's rotational angle by 21.8% compared to an intact joint. In contrast, static standing with internal rotation led to a similar increase in stress and a nearly 2.5 times increase in the talus rotational angle.

Conclusion

Injury to the DL altered the stress distribution in the tibiotalar joint and increased the talus rotation angle when subjected to a rotational torque, which may increase the risk of RAI. When treating RAI, it is essential to address not only multi-band DL injuries but also single-band deep DL injuries, especially those affecting the ATTL.

Plantar intrinsic foot muscle activity and its relationship with postural sway during tiptoe standing in ballet dancers and non-dancers

BACKGROUND

Minimizing postural sway during tiptoe standing is essential for ballet dancers. Investigation of the activity of the plantar intrinsic foot muscles (PIFMs) may provide insight into postural sway in dancers. Herein, we compared PIFM activity during tiptoe standing between dancers and non-dancers and examined its relationship with postural sway.

METHODS

We enrolled 14 female ballet dancers and 13 female non-dancers. Electromyography (EMG) amplitudes of 64 channels of PIFMs and center of pressure (COP) data were recorded during bipedal tiptoe standing tasks performed with ankle plantarflexion angles of 20°, 40°, and 60° (dancers only). The EMG amplitudes were normalized to those during the maximum voluntary contraction, and the muscle activity level and its coefficient of variation over time (EMG-CVtime) during the task were assessed. Standard deviations in the anteroposterior and mediolateral directions, velocity, and area were calculated from the COP data.

RESULTS

Most COP and EMG variables were significantly lower in dancers than in non-dancers in both the 20° and 40° tasks (p < 0.05). Significant correlations were found between most combinations of the COP and EMG variables in both the 20° and 40° tasks in the whole cohort (r = 0.468-0.807, p ≤ 0.014). In the 60° task in dancers, COP velocity was strongly correlated with EMG-CVtime (r = 0.700, p = 0.005).

CONCLUSION

These results provide novel evidence that the PIFMs do not require high activity, but rather that its low, steady activity is the key, to achieve less postural sway during bipedal tiptoe standing in dancers.

Ankle bone morphology affects the size of non-trauma related osteochondral lesions of the talus in skeletally immature children

BACKGROUND

This study aimed to elucidate the relationship between ankle morphology and the size of non-trauma related osteochondral lesions of the talus (OLT), because approximately half the OLT found in children is of unknown origin.

METHODS

34 ankles in 30 skeletally immature children with OLTs who underwent preoperative magnetic resonance imaging (MRI) were evaluated. Parameters measured included area of the OLT, tibial axis-medial malleolus angle (TMM), malleolar width (MalW), and talar surface angle (TSA; defined as the angle between the line perpendicular to the mid-diaphysis of the tibia and the talar joint surface; medial inclination, positive). The ankles were divided into two groups: the trauma group had a history of injury and the idiopathic group had no history of injury. The correlation between lesion area and MRI parameters were evaluated in each group.

RESULTS

Thirteen ankles in 13 patients comprised the trauma group, while 21 ankles in 17 patients were in the idiopathic group. Of the 17 patients in the idiopathic group, four had bilateral OLT. In the trauma group, MalW was significantly correlated with the area (r = 0.827, P = 0.0001). In the idiopathic group, TMM and MalW were significantly correlated with the area (r = 0.608, P = 0.003 and r = 0.566, P = 0.008). TSA was positively correlated with area in the idiopathic group (r = 0.516, P = 0.017), but negatively correlated with area in the trauma group (r = -0.609, P = 0.027). The other parameters showed no significant correlation.

CONCLUSIONS

The size of non-trauma related OLTs may have been affected by an ankle morphology showing poor bone conformity, such as an open medial malleolus and inclined talar joint surface. In addition, the evaluation of the contralateral ankle joint may be crucial when patients with OLT have no specific history of trauma.

Frontal plane ankle stiffness increases with axial load independent of muscle activity

Ankle sprains are the most common musculoskeletal injury, typically resulting from excessive inversion of the ankle. One way to prevent excessive inversion and maintain ankle stability is to generate a stiffness that is sufficient to resist externally imposed rotations. Frontal-plane ankle stiffness increases as participants place more weight on their ankle, but whether this effect is due to muscle activation or axial loading of the ankle is unknown. Identifying whether and to what extent axial loading affects ankle stiffness is important in understanding what role the passive mechanics of the ankle joint play in maintaining its stability. The objective of this study was to determine the effect of passive axial load on frontal-plane ankle stiffness. We had subjects seated in a chair as an axial load was applied to the ankle ranging from 10% to 50% body weight. Small rotational perturbations were applied to the ankle in the frontal plane to estimate stiffness. We found a significant, linear, 3-fold increase in ankle stiffness with axial load from the range of 0% body weight to 50% body weight. This increase could not be due to muscle activity as we observed no significant axial-load-dependent change in any of the recorded muscle activations. These results demonstrate that axial loading is a significant contributor to maintaining frontal-plane ankle stability, and that disruptions to the mechanism mediating this sensitivity of stiffness to axial loading may result in pathological cases of ankle instability.

Early radiographic outcomes following deltoid ligament repair in bimalleolar equivalent ankle fractures

BACKGROUND

Indications for deltoid ligament repair in bimalleolar equivalent ankle fractures are unclear. This study compared radiographic outcomes in bimalleolar equivalent ankle fractures undergoing open reduction internal fixation (ORIF) +/- deltoid ligament repair.

METHODS

A retrospective review of 1024 ankle fractures was performed. Bimalleolar equivalent injuries treated with ORIF +/- deltoid ligament repair were included. Radiographic assessment was performed preoperatively, and at three months postoperatively.

RESULTS

One hundred and forty-seven ankle fractures met inclusion criteria with 46 undergoing deltoid ligament repairs. There was a significant decrease in medial clear space (1.93 ± 0.65 mm vs. 2.26 ± 0.64 mm, p = 0.01), and tibiofibular clear space (3.89 ± 1.20 mm vs. 4.87 ± 1.37 mm, p = 0.0001) at 3 months postoperative in the deltoid repair group compared to the no repair group. When syndesmotic fixation was performed, there were no differences between groups.

CONCLUSION

Deltoid ligament repair in bimalleolar equivalent ankle fractures resulted in reduced medial clear space, and tibiofibular clear space in the early postoperative period. These differences were small and remained within established normal limits.

LEVEL OF CLINICAL EVIDENCE

Level III, retrospective cohort study.

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.

Eccentric ankle arthritis in the sagittal plane: a novel description of anterior and posterior ankle arthritis

BACKGROUND

To report radiographic characteristics of anterior and posterior ankle arthritis, which demonstrates the eccentric narrowing of either aspect of the tibiotalar joint in the sagittal plane.

METHODS

Radiographic analysis of 19 ankles with anterior arthritis and 16 ankles with posterior arthritis was performed, which were defined as having both (1) eccentric narrowing of the anterior or posterior tibiotalar joint space on lateral radiographs and (2) talar tilt angle less than 4 degrees on anteroposterior radiographs. Measured radiographic parameters were: Talar tilt angle, medial distal tibial angle (MDTA), talar center migration (TCM), anterior distal tibial angle (ADTA), tibial axis-to-talus ratio (TT ratio), talo-first metatarsal (Meary) angle, hindfoot alignment angle (HAA), hindfoot moment arm, and mechanical axis deviation (MAD). An Intergroup comparison analysis, including a normal control group, was also performed.

RESULTS

The TT ratio was significantly different between each group, indicating a distinct talus position in the sagittal plane. The anterior group had a significantly larger TCM than the control group and lower ADTA compared to other groups, indicating medial translation of the talus and anterior opening of the tibial plafond. The posterior group demonstrated a significantly higher Meary angle and lower HAA compared to other groups and lower MDTA compared to the control group, indicating lower medial longitudinal arch, valgus heel alignment, and varus tibial plafond. The MAD was significantly higher in both the anterior and posterior groups than the control group, indicating varus lower limb alignment.

CONCLUSION

Anterior ankle arthritis demonstrated anteromedial translation of the talus and anterior opening of the tibial plafond. Posterior ankle arthritis was associated with the lower medial longitudinal arch and hindfoot valgus, indicating an association with flatfoot deformity. Both anterior and posterior ankle arthritis were associated with varus lower limb alignment.

Frontal plane ankle stiffness increases with weight-bearing

Ankle sprains are among the most common musculoskeletal injuries. They are not isolated innocuous injuries as 30-40% of people who sprain their ankles develop chronic ankle instability. Ankle instability is typically assessed under passive unloaded conditions, ignoring any potential contribution of joint loading or muscle activation to the maintenance of ankle stability. Thus, the relevance of unloaded ankle stability assessments to the evaluation of impairments in chronic ankle instability or the prediction of future ankle sprains is questionable. Ankle impedance, which quantifies the resistance to an imposed rotation, has often been used to quantify ankle stability. However, few studies have investigated impedance in the frontal plane where sprains occur, and none have systematically investigated the effect of weight-bearing on ankle impedance. The objective of this study was to determine whether weight-bearing affects frontal plane ankle impedance. We had subjects systematically alter the weight on the tested ankle, while imposed frontal plane rotations were applied to estimate the impedance. We found that ankle stiffness, the static component of impedance, increased proportionally with the weight on the ankle. This increase in stiffness was due to a combination of the increase loading on the joint and the increase in muscle activation that occurs during weight-bearing. Finally, we found that men had a greater stiffness than women over the majority of the weight-bearing range. These results highlight the importance of clinically assessing ankle stability during weight-bearing conditions to better determine the impairments in chronic ankle instability and identify those at risk for ankle sprains.

The anterior talofibular ligament-posterior talofibular ligament angle decreased after ankle lateral stabilization surgery

PURPOSE

The angle between the anterior talofibular ligament (ATFL) and the posterior talofibular ligament (PTFL) is increased in patients with chronic ATFL injury. This study aimed to compare the AFTL-PTFL angle before versus after ankle lateral stabilization surgery, and to evaluate whether the ATFL-PTFL angle correlates with the ligament injury severity.

METHODS

This retrospective study included 48 patients with mechanical ankle instability treated between 2016 and 2018. After arthroscopic evaluation, all patients underwent ankle lateral stabilization surgery comprising ligament repair (n = 28) or reconstruction (n = 20). The ATFL-PTFL angle was measured in the axial plane on pre- and postoperative MRI. Comparisons were made of the pre- versus postoperative ATFL-PTFL angles, and the ATFL-PTFL angle of the repair versus reconstruction groups. Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic performance of the ATFL-PTFL angle in selecting the surgical technique.

RESULTS

The postoperative ATFL-PTFL angle was significantly decreased compared with preoperatively. The ATFL-PTFL angle was significantly smaller in the repair group than the reconstruction group preoperatively and postoperatively. The area under the ROC curve was 0.741 (P < 0.01). The optimal cutoff point for the selection of ligament reconstruction was an ATFL-PTFL angle of 89.4° (sensitivity 0.85, specificity 0.61).

CONCLUSION

The ATFL-PTFL angle decreases after ankle lateral stabilization surgery. The ATFL-PTFL angle is related to the severity of the ATFL injury. Ankle lateral ligament reconstruction should be considered when the ATFL-PTFL angle is > 89.4°.

LEVEL OF EVIDENCE

Level III.

Deep deltoid ligament injury is related to rotational instability of the ankle joint: a biomechanical study

PURPOSE

In the athletic population, the prevalence of isolated syndesmotic lesions is high. To detect potential instability of the ankle is crucial to define those lesions in need of surgical management. The aim was to define how the extent of tibio-fibular syndesmotic ligament injury influences the overall stability of the ankle joint in a cadaver model.

METHODS

Twenty fresh-frozen through knee cadaveric leg specimens were subjected to different simulated syndesmotic ligament lesions. In Group 1 (n = 10), the order of ligament sectioning was: anterior tibio-fibular ligament (ATFL), superficial deltoid ligament (SDL), deep deltoid ligament (DDL), posterior tibio-fibular ligament (PTFL), and progressive sectioning at 10, 50 and 100 mm of the distal interosseous membrane (IOM). In Group 2 (n = 10), the sequence was: ATFL, PITFL, 10 and then 50 mm of the distal IOM, SDL, DDL, and 100 mm of the distal IOM. Diastasis of 4 mm in the coronal or sagittal plane and external rotation of the ankle greater than 20° were considered indicative of instability.

RESULTS

Both coronal and sagittal diastasis exceeded 4 mm with injury patterns characterized by IOM lesions extending beyond 5 cm. External rotation of the ankle exceeded 20° with injury patterns characterized by a DDL lesion.

CONCLUSION

Coronal and sagittal plane diastases of the tibio-fibular syndesmosis are particularly affected by sequential lesions involving the IOM, whereas increased external rotation of the ankle most depends on DDL. The identification of the specific syndesmotic and deltoid ligament injuries is crucial to understanding which lesions need operative management. The knowledge of which pattern of tibio-fibular syndesmotic ligament injury influences the ankle joint stability is crucial in defining which lesions need for surgical management.

Deltoid Ligament Injuries Associated With Ankle Fractures: Arguments For and Against Direct Repair

Ankle fractures are an extremely common orthopaedic injury treated by surgeons on a routine basis. The deltoid ligament is torn in a large number of these fractures and is commonly seen with associated radiographic changes of medial clear space widening. The clinical relevance of addressing the injured deltoid ligament with acute surgical repair has been debated for decades. The early literature documenting repair or reconstruction of the deltoid ligament dates back to the 1950s. Most commonly, orthopaedic surgeons restore the lateral column directly with fibula fracture fixation. The injury may then be further evaluated intraoperatively by stress testing to ensure syndesmosis integrity and mortise stability with indirect medial column reduction, which allows for secondary healing of the medial deltoid ligamentous complex. This popular treatment paradigm is based primarily on literature from the 1980s and has not been thoroughly evaluated with modern surgical implants, techniques, and research methods. A review and background of the supportive literature for and against deltoid ligament repair in the setting of acute ankle fractures is presented. Undeniably, the deltoid ligament complex has been proven to confer some element of stability to maintaining a congruent ankle mortise. The commonly cited data in favor of not repairing the deltoid ligament warrants careful consideration to allow accuracy in obtaining the best patient outcomes with the most predictable surgical methods available.

Is load control necessary to produce physiological AP displacement and axial rotation in wear testing of TAR?

The International Standard Organization, ISO 22622, specifies two options for joint wear simulator evaluation of total ankle replacements (TARs): load-controlled and displacement-controlled. In the present study, the load-controlled testing parameters were applied to cadaveric specimens to quantify and compare the observed sagittal translations and axial rotations to those specified under the displacement-controlled option. Twelve cadaveric specimens were stripped of extraneous tissues, keeping surrounding ankle ligaments. A halo was used to produce plantarflexion and dorsiflexion of the talus through two screws, while a baseplate resisted axial loads. The axial force and torque were applied to the tibia and fibula under force and torque feedback control. An anterior-posterior force was applied to the tibia. Plantarflexion-dorsiflexion were applied using rotation control. To protect the cadaveric specimens, loads were applied at 50% of the specified load profile while plantarflexion-dorsiflexion rotation was applied as specified. There was variation among specimens in magnitudes of anterior-posterior displacement with peaks ranging from 3.3 mm posteriorly to 3.0 mm anteriorly. Likewise, there was variation among specimens in magnitude of axial rotation, with peaks ranging from 11° external rotation to 4.5° internal rotation. However, the mean magnitudes of AP displacement and axial rotation did not exceed those specified by ISO 22622.

A systematic review of the "Logsplitter" injury: how much do we know?

BACKGROUND

As an emerging proposed type of ankle joint injury, the concept of logsplitter injury is a unified overview of the high-energy ankle fracture and dislocation accompanied by distal tibiofibular syndesmosis separation and displacement. Since the concept of logsplitter injury is still relatively novel, there is no uniform standard for its clinical classification, diagnosis and treatment currently. Thus, we reviewed previous literatures here to provide certain references for its better clinical diagnosis and treatment in future.

METHODS

The available literatures from January 1985 to June 2020 in five medical databases were searched and analyzed. The original articles that evaluated the outcomes of patients treated surgically for the logsplitter injury were included. The detailed data were then extracted from each research, including the researchers, type of study, level of evidence, type of center research, groups, number of patients, gender, age, causes of injury, time from injury to surgery, operative time, intraoperative blood loss, length of follow-up, postoperative complications and clinical outcomes. The overall search procedures were performed by the two independent reviewers.

RESULTS

Seven pieces of researches (199 patients) were eligible for inclusion. All researches were either retrospective or prospective study, and all but one was single center study. Falling from height ranked first in the causes of injury (52.8%), and followed by the traffic accidents (29.6%). Clinical outcomes were all measured using the American Orthopaedic Foot and Ankle Society (AOFAS) score, and the mean AOFAS score at the final follow-up was 77.9 points.

CONCLUSIONS

None of the definitive consensuses exists on how logsplitter injury should be diagnosed and surgically managed. In light of the novel concept, short presentation time and numerous postoperative complications, the logsplitter injury has not been well understood by most surgeons currently, and its overall situation still needs to be supported by a larger sample size of multicenter research in the future.

Biomechanical evaluation of total ankle arthroplasty. Part I: Joint loads during simulated level walking

In total ankle arthroplasty, the interaction at the joint between implant and bone is driven by a complex loading environment. Unfortunately, little is known about the loads at the ankle during daily activities since earlier attempts use two- or three-dimensional models to explore simplified joint mechanics. Our goal was to develop a framework to calculate multi-axial loads at the joint during simulated level walking following total ankle arthroplasty. To accomplish this, we combined robotic simulations of level walking at one-quarter bodyweight in three cadaveric foot and ankle specimens with musculoskeletal modeling to calculate the multi-axial forces and moments at the ankle during the stance phase. The peak compressive forces calculated were between 720 and 873 N occurring around 77%-80% of stance. The peak moment, which was the internal moment for all specimens, was between 6.1 and 11.6 N m and occurred between 72% and 88% of the stance phase. The peak moment did not necessarily occur with the peak force. The ankle joint loads calculated in this study correspond well to previous attempts in the literature; however, our robotic simulator and framework provide an opportunity to resolve the resultant three-dimensional forces and moments as others have not in previous studies. The framework may be useful to calculate ankle joint loads in cadaveric specimens as the first step in evaluating bone-implant interactions in total ankle replacement using specimen specific inputs. This approach also provides a unique opportunity to evaluate changes in joint loads and kinematics following surgical interventions of the foot and ankle.

Effects of lateral ankle sprain on range of motion, strength and postural balance in competitive basketball players: a cross-sectional study

BACKGROUND

Lateral ankle sprain is the most common injury in basketball, and many of these sprains resulted in residual functional deficits. This study aimed to compare ankle strength and range of motion, and postural balance between competitive basketball players with and without lateral ankle sprain.

METHODS

This was a cross-sectional study involving 42 male competitive basketball players. Subjects were divided into the injured and uninjured groups based on self-reported questionnaires. Ankle range of motion (ROM) was measured using a goniometer, ankle isokinetic strength testing performed using Biodex System 4 PRO, and single-leg stability tests performed using Biodex Balance System SD.

RESULTS

Between the injured and uninjured ankles, there was a decrease in plantarflexion ROM (44.89±6.85 vs. 50.75±9.31, P<0.05) and an increase in eversion ROM (14.50±5.63 vs. 11.74±4.53, P<0.05). There was a reduction in inversion and plantarflexion strength at 30°/s peak torque and 120 °/s peak torque (P<0.05). However, no significant difference observed in the postural stability indexes between the two groups.

CONCLUSIONS

This study proves that there are residual ROM and strength deficits after an ankle sprain, however, these deficits do not affect their balance ability.

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.

An extended discrete element method for the estimation of contact pressure at the ankle joint during stance phase

Abnormalities in the ankle contact pressure are related to the onset of osteoarthritis. In vivo measurements are not possible with currently available techniques, so computational methods such as the finite element analysis (FEA) are often used instead. The discrete element method (DEM), a computationally efficient alternative to time-consuming FEA, has also been used to predict the joint contact pressure. It describes the articular cartilage as a bed of independent springs, assuming a linearly elastic behaviour and absence of relative motion between the bones. In this study, we present the extended DEM (EDEM) which is able to track the motion of talus over time. The method was used, with input data from a subject-specific musculoskeletal model, to predict the contact pressure in the ankle joint during gait. Results from EDEM were also compared with outputs from conventional DEM. Predicted values of contact area were larger in EDEM than they were in DEM (4.67 and 4.18 cm², respectively). Peak values of contact pressure, attained at the toe-off, were 7.3 MPa for EDEM and 6.92 MPa for DEM. Values predicted from EDEM fell well within the ranges reported in the literature. Overall, the motion of the talus had more effect on the extension and shape of the pressure distribution than it had on the magnitude of the pressure. The results indicated that EDEM is a valid methodology for the prediction of ankle contact pressure during daily activities.

Reverse anterolateral drawer test is more sensitive and accurate for diagnosing chronic anterior talofibular ligament injury

PURPOSE

To diagnose chronic anterior talofibular ligament (ATFL) injury, three different physical examinations were compared: the anterior drawer test (ADT), the anterolateral drawer test (ALDT), and the reverse anterolateral drawer test (RALDT).

METHODS

A total of 72 ankles from potential ATFL-injured patients and the normal population were included and examined using the ADT, ALDT, and RALDT by two examiners without knowing the injury histories of any of the participants. Ultrasound examination was then applied as the gold standard to divide the ankles into the ATFL-injured group and the control group. The sensitivity (Se), specificity (Sp), false negative rate (FNR), false positive rate (FPR), accuracy, κ value, and p value of the two examiners' diagnoses were calculated to assess the diagnostic ability of each examination.

RESULTS

There were 38 ankles in the injured group and 34 ankles in the control group. No significant difference was found between the two groups in terms of gender, age, body mass index (BMI), and included ankles. In the ADT and ALDT groups, the specificity reached one, while the sensitivity was relatively low (0.053 and 0.477 for the junior examiner and 0.395 and 0.500 for the senior examiner). In the RALDT, both the sensitivity and specificity were greater than 85% (0.868 and 0.912 for the senior examiner and 0.921 and 0.882 for the junior examiner). The κ value of the RALDT (0.639) was higher than that of the ALDT (0.528) and the ADT (0.196), whereas all the p values were less than 0.05.

CONCLUSION

The ADT and ALDT are valuable physical tests to assess ATFL injuries. Compared with the traditional ADT and ALDT, however, the RALDT is more sensitive and accurate in diagnosing chronic ATFL injuries.

LEVEL OF EVIDENCE

II (diagnostic).

Adding deltoid ligament repair in ankle fracture treatment: Is it necessary? A systematic review

BACKGROUND

Deltoid ligament injuries are typically caused by supination-external rotation or pronation injury. Numerous ligament reconstruction techniques have been proposed; however, clear indications for operative repair have not yet been well established in the literature.

METHODS

We reviewed primary research articles comparing ORIF treatment for ankle fracture with versus without deltoid ligament repair.

RESULTS

Five studies were identified with a total of 281 patients. 137 patients underwent ORIF with deltoid repair, while 144 patients underwent ORIF without deltoid ligament repair. Clinical, radiographic, and functional outcomes, as well as complications were considered. The average follow-up was 31 months (range, 5-120).

CONCLUSIONS

Current literature does not provide clear indication for repair of the deltoid ligament at the time of ankle fracture repair. There may be some advantages of adding deltoid ligament repair for patients with high fibular fractures or in patients with concomitant syndesmotic fixation.

LEVEL OF CLINICAL EVIDENCE

III.

Diagnosis and Management of Deltoid Ligament Insufficiency

Background:

Surgical management of patients with acute and chronic ankle instability (CAI) has historically focused on the lateral ligament complex. Recent studies in CAI patients have shown that magnetic resonance imaging (MRI) and arthroscopy demonstrate concomitant injury to the deltoid ligament complex We performed a systematic review to determine if consistent clinical, diagnostic imaging, or arthroscopic findings of deltoid ligament injury in the setting of CAI have been described. In addition, we sought to determine if treatment options and/or clinical outcomes have been described.

Methods:

A systematic review was conducted using the PubMed, MEDLINE, and Embase databases. Articles were included if they had a majority of patients 18 years of age or older, focused on deltoid ligament injury in ankle instability, and reported diagnostic and/or treatment methods. Articles were excluded if the study focused on the deltoid ligament in the acute fracture setting. All included articles were assessed for diagnostic criteria, treatments, and patient outcomes.

Results:

Our search yielded 157 articles, of which a total of 13 were included in our study. Arthroscopy was described as the gold standard to diagnose and evaluate the severity of deltoid ligament injury, however, little objective data on the arthroscopic diagnosis of deltoid ligament insufficiency was reported. MRI was the imaging modality of choice to evaluate deltoid ligament injury and had a high sensitivity and specificity when compared with arthroscopy. No standard MRI diagnostic criteria for deltoid ligament injury were identified in the literature. Specific treatment techniques and long-term outcomes were not well described in the manuscripts included in this review.

Conclusion:

There is limited knowledge on deltoid ligament insufficiency in the setting of chronic ankle instability. Criteria for characterizing deltoid ligament damage with diagnostic imaging appear to be evolving, but there is no standard classification. Only 1 author has described a method to evaluate deltoid ligament competency on arthroscopic examination. There are currently no objective data to guide treatment decisions.

Level of Evidence:

Level III.

Deltoid ligament repair reduces and stabilizes the talus in unstable ankle fractures

Introduction

Treatment of supination external rotation type IV (SER-IV) ankle injuries has focused on reduction and fixation of the fibula and syndesmosis (ORIF), not repair of the deltoid ligament.

Methods

Twenty-one ankles were analyzed with a motion capture system. Uninjured ankles were stressed and compared to ankles with SER-IV injuries, then with ORIF, and finally ORIF and deltoid repair.

Results

After deltoid ligament repair, talar coronal and axial rotation normalized to the uninjured state and were significantly reduced compared to ORIF alone.

Discussion

Deltoid ligament repair after an SER-IV ankle injury can help directly reduce and stabilize the tibiotalar joint.

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.

Evaluation of Transsyndesmotic Fixation and Primary Deltoid Ligament Repair in Ankle Fractures With Suspected Combined Deltoid Ligament Injury

The present prospective study examined the utility of the intraoperative tap test/technique for distal tibiofibular syndesmosis in the diagnosis of deltoid ligament rupture and compared the outcomes of transsyndesmotic fixation to deltoid ligament repair with suture anchor. This diagnostic technique was performed in 59 ankle fractures with suspected deltoid ligament injury. The width of the medial clear space of 59 cases was evaluated to assess the sensitivity and specificity. Those with deltoid ligament rupture were randomly assigned to 2 groups and treated with deltoid ligament repair with a suture anchor or with syndesmosis screw fixation. All the patients were assessed with the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale, short-form 36-item questionnaire (SF-36), and visual analog scale (VAS). The tap test was positive in 53 cases. However, surgical exploration demonstrated that 51 cases (86.4%) had a combined deltoid ligament injury and fracture. The sensitivity and specificity of the tap test was 100.0% and 75.0%, respectively. Finally, 26 cases (96.3%) in the syndesmosis screw group and 22 (91.7%) in the deltoid repair group were followed up. No statistically significant differences were found in the AOFAS ankle-hindfoot scale score, SF-36 score, or VAS score between the 2 groups. The malreduction rate in the syndesmosis screw group was 34.6% and that in the deltoid repair group was 9.09%. The tap test is an intraoperative diagnostic method to use to evaluate for deltoid ligament injury. Deltoid ligament repair with a suture anchor had good functional and radiologic outcomes comparable to those with syndesmotic screw fixation but has a lower malreduction rate. We did not encounter the issue of internal fixation failure or implant removal.

Investigation of factors related to the occurrence of osteochondral lesions of the talus by 3D bone morphology of the ankle

Aims

The aims of this study were to evaluate the morphology of the ankle in patients with an osteochondral lesion of the talus using 3D CT, and to investigate factors that predispose to this condition.

Patients and Methods

The study involved 19 patients (19 ankles) who underwent surgery for a medial osteochondral lesion (OLT group) and a control group of 19 healthy patients (19 ankles) without ankle pathology. The mean age was significantly lower in the OLT group than in the control group (27.0 vs 38.9 years; p = 0.02). There were 13 men and six women in each group. 3D CT models of the ankle were made based on Digital Imaging and Communications in Medicine (DICOM) data. The medial malleolar articular and tibial plafond surface, and the medial and lateral surface area of the trochlea of the talus were defined. The tibial axis-medial malleolus (TMM) angle, the medial malleolar surface area and volume (MMA and MMV) and the anterior opening angle of the talus were measured.

Results

The mean TMM angle was significantly larger in the OLT group (34.2°, sd 4.4°) than in the control group (29.2°, sd 4.8°; p = 0.002). The mean MMA and MMV were significantly smaller in the OLT group than in the control group (219.8 mm2, sd 42.4) vs (280.5 mm2, sd 38.2), and (2119.9 mm3, sd 562.5) vs (2646.4 mm3, sd 631.4; p < 0.01 and p = 0.01, respectively). The mean anterior opening angle of the talus was significantly larger in the OLT group than in the control group (15.4°, sd 3.9°) vs (10.2°, sd 3.6°; p < 0.001).

Conclusion

3D CT measurements showed that, in patients with a medial osteochondral lesion of the talus, the medial malleolus opens distally, the MMA and MMV are small, and the anterior opening angle of the talus is large. This suggests that abnormal morphology of the ankle predisposes to the development of osteochondral lesions of the talus. Cite this article: Bone Joint J 2018;100-B:1487–90.

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.

[Injuries of the medial collateral ligament and spring ligament complexes]

The medial collateral ligament (MCL) complex is characterized by a complex anatomical arrangement of the individual ligamentous structures including three joints and the spring ligament complex. Biomechanically it serves as the main stabilizing structure in the ankle region against rotational and pronating forces. Lesions in the region of the MCL complex are more frequent than previously thought and like lesions of the spring ligament complex can lead to pain and instability. A thorough examination including the patient history with possible injury mechanisms often yields valuable information on the diagnosis of injuries to the MCL or spring ligament complex. In many cases these are primarily overlooked and concomitant lesions, such as fractures, syndesmotic and lateral ligament lesions frequently occur; however, the clinical assessment of stability is often primarily impossible in an acute setting. High-resolution magnetic resonance imaging (MRI) plays a key role in identifying the ligamentous components. In addition, MRI plays a supportive role in the preoperative planning before reconstruction of acute and especially chronic lesions. In most cases the surgical treatment of acute ruptures of the MCL is not indicated. Various options for treatment of acute and chronic lesions of the MCL and spring ligament complex are available including the use of free tendon grafts. Controversy exists regarding the operative treatment of MCL lesions in the case of ankle fractures. It is recommended for cases with impinging tissue in the medial gutter serving as a barrier to adequate reduction of the joint and in cases of unstable fractures after reduction.

Short-Term Results of a Ruptured Deltoid Ligament Repair During an Acute Ankle Fracture Fixation

BACKGROUND

There is no consensus on the optimal treatment or preferred method of operation for the management of acute deltoid ligament injuries during an ankle fracture fixation. This study aimed to analyze the outcomes of repairing the deltoid ligament during the fixation of an ankle fracture compared to conservative management.

METHODS

We retrospectively evaluated 78 consecutive cases of a ruptured deltoid ligament with an associated ankle fracture between 2001 and 2016. All of the ankle fractures were treated with a plate and screw fixation. Patients in the conservative treatment for ruptured deltoid ligament underwent management from 2001 to 2008 (37 fractures, group 1), while the operative treatment for ruptured deltoid ligament was included from 2009 to 2016 (41 fractures, group 2). The outcome measures included radiographic findings, the American Orthopaedic Foot & Ankle Society ankle-hindfoot scores, visual analog scale scores, and the Foot Function Index. All patients were followed for an average of 17 months.

RESULTS

Radiologic findings in both groups were comparable, but the final follow-up of the medial clear space (MCS) was significantly smaller in the group 2 ( P < .01). Clinical outcomes were similar between the two groups ( P > .05). Comparing those who underwent syndesmotic fixation between both groups, group 2 showed a significantly smaller final follow-up MCS, and all clinical outcomes were better in group 2 ( P < .05). Linear regression analysis showed that the final follow-up MCS had a significant influence on clinical outcomes ( P < .05).

CONCLUSION

Although the clinical outcomes were not significantly different between the 2 groups, we obtained a more favorable final follow-up MCS in the deltoid repair group. Particularly when accompanied by a syndesmotic injury, the final follow-up MCS and the clinical outcomes were better in the deltoid repair group. In the case of high-grade unstable fractures of the ankle with syndesmotic instability, a direct repair of the deltoid ligament was adequate for restoring medial stability.

LEVEL OF EVIDENCE

Level III, retrospective comparative case series.

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

BACKGROUND

Numerous biomechanical studies of the lateral ankle ligaments have been reported; however, the isolated function of the calcaneofibular ligament has not been clarified. We hypothesize that the calcaneofibular ligament would stabilize the ankle joint complex under multidirectional loading, and that the in situ force in the calcaneofibular ligament would change in each flexed position.

METHODS

Using seven fresh frozen cadaveric lower extremities, the motions and forces of the intact ankle under multidirectional loading were recorded using a 6-degree-of-freedom robotic system. On repeating these intact ankle joint complex motions after the calcaneofibular ligament transection, the in situ force in the calcaneofibular ligament and the contribution of the calcaneofibular ligament to ankle joint complex stability were calculated. Finally, the motions of the calcaneofibular ligament-transected ankle joint complex were recorded.

FINDINGS

Under an inversion load, significant increases of inversion angle were observed in all the flexed positions following calcaneofibular ligament transection, and the calcaneofibular ligament accounted for 50%-70% of ankle joint complex stability during inversion. The in situ forces in the calcaneofibular ligament under an anterior force, inversion moment, and external rotation moment were larger in the dorsiflexed position than in the plantarflexed position.

INTERPRETATION

The calcaneofibular ligament plays a role in stabilizing the ankle joint complex to multidirectional loads and the role differs with load directions. The in situ force of the calcaneofibular ligament is larger at the dorsiflexed position. This ligament provides the primary restraint to the inversion ankle stability.

Predicting tibiotalar and subtalar joint angles from skin-marker data with dual-fluoroscopy as a reference standard

Evidence suggests that the tibiotalar and subtalar joints provide near six degree-of-freedom (DOF) motion. Yet, kinematic models frequently assume one DOF at each of these joints. In this study, we quantified the accuracy of kinematic models to predict joint angles at the tibiotalar and subtalar joints from skin-marker data. Models included 1 or 3 DOF at each joint. Ten asymptomatic subjects, screened for deformities, performed 1.0m/s treadmill walking and a balanced, single-leg heel-rise. Tibiotalar and subtalar joint angles calculated by inverse kinematics for the 1 and 3 DOF models were compared to those measured directly in vivo using dual-fluoroscopy. Results demonstrated that, for each activity, the average error in tibiotalar joint angles predicted by the 1 DOF model were significantly smaller than those predicted by the 3 DOF model for inversion/eversion and internal/external rotation. In contrast, neither model consistently demonstrated smaller errors when predicting subtalar joint angles. Additionally, neither model could accurately predict discrete angles for the tibiotalar and subtalar joints on a per-subject basis. Differences between model predictions and dual-fluoroscopy measurements were highly variable across subjects, with joint angle errors in at least one rotation direction surpassing 10° for 9 out of 10 subjects. Our results suggest that both the 1 and 3 DOF models can predict trends in tibiotalar joint angles on a limited basis. However, as currently implemented, neither model can predict discrete tibiotalar or subtalar joint angles for individual subjects. Inclusion of subject-specific attributes may improve the accuracy of these models.

The contribution of anterior deltoid ligament to ankle stability in isolated lateral malleolar fractures

The treatment of isolated lateral malleolar fractures with deltoid ligament rupture remains controversial. We prospectively analysed 35 patients with isolated lateral malleolar fractures during 2006-2013. Radiography and magnetic resonance imaging (MRI) were performed to assess the degree of reduction, ligament damage, and stability. Internal fixation was performed for all unstable valgus fractures with unacceptable fracture parameters. Fractures with residual valgus instability after fixation underwent anterior deltoid repair. The mean anterior deltoid ligament grade based on MRI was significantly different between the high-grade unstable group and the stable and low-grade unstable groups (p=0.037 and 0.004, respectively). Postoperative medial clear space measurements were not significantly different between groups. MRI was shown to be a useful tool in the preoperative identification of isolated lateral malleolus fractures prone to valgus instability. In the case of high-grade unstable fractures of the lateral malleolus, repair of the anterior deltoid ligament is adequate for restoring medial stability.

Peroneal tendinosis as a predisposing factor for the acute lateral ankle sprain in runners

PURPOSE

A painful episode in the region of the peroneal tendons, within the retromalleolar groove, is a common precipitating event of an acute lateral ankle sprain. A forefoot striking pattern is suspected to cause peroneal tendinosis. The aim of this study is to analyse the role of peroneal tendinosis as a predisposing factor for ankle sprain trauma in runners.

METHODS

Fifty-eight runners who had experienced acute ankle sprain trauma, with pre-existing pain episodes for up to 4 weeks in the region of the peroneal tendons, were assessed clinically. Fractures were excluded by conventional radiography. An magnetic resonance imaging (MRI) scan had been performed within 14 days after the traumatic event and was subsequently evaluated by two experienced radiologists.

RESULTS

MRI revealed peroneal tendinosis in 55 patients (95% of the total study population). Peroneus brevis (PB) tendinosis was found in 48 patients (87% of all patients with peroneal tendinosis), and peroneus longus (PL) tendinosis was observed in 42 cases (76%). Thirty-five patients (64%) had combined PB and PL tendinosis. A lesion of the anterior talofibular ligament was found to be the most common ligament injury associated with peroneal tendinosis (29 cases; 53%), followed by a lesion of the calcaneofibular ligament (16 cases; 29%) and a lesion of the posterior tibiofibular ligament (13 cases; 24%).

CONCLUSION

The results of this study reflect the correlation between peroneal tendinosis and ankle sprain trauma. Injuries of one or more ligaments are associated with further complications. A period of rest or forbearance of sports as well as adequate treatment of the peroneal tendinosis is essential to prevent subsequent ankle injuries, especially in runners. Modification of the running technique would also be beneficial.

LEVEL OF EVIDENCE

IV.

Anterolateral Drawer Versus Anterior Drawer Test for Ankle Instability: A Biomechanical Model

BACKGROUND

The addition of unconstrained internal rotation to the physical examination could allow for detection of more subtle degrees of ankle instability. We hypothesized that a simulated anterolateral drawer test allowing unconstrained internal rotation of the ankle would provoke greater displacement of the lateral talus in the mortise versus the anterior drawer test.

METHODS

Ten cadaveric lower extremities were tested in a custom apparatus designed to reproduce the anterior drawer test and the anterolateral drawer test, in which the ankle was allowed to internally rotate about the intact deep deltoid ligament while being subluxed anteriorly. Specimens were tested intact and with anterior tibiofibular ligament sectioned. A differential variable reluctance transducer was used to measure lateral talar displacement with anterior forces of 25 and 50 N.

RESULTS

No significant differences in talar displacement or ankle rotation were noted in intact specimens between the groups. Among sectioned specimens, significantly more talar displacement (25 N [6.5 ± 1.7 mm vs 3.8 ± 2.4 mm] and 50 N [8.7 ± 0.9 mm vs 4.5 ± 2.5 mm], P < .001) and ankle rotation (25 N [13.9 ± 8.0 degrees vs 0.0 ± 0.0 degrees] and 50 N [23.7 ± 5.8 degrees vs 0.0 ± 0.0 degrees], P < .001) were found in the anterolateral drawer versus anterior drawer group.

CONCLUSION

In an ankle instability model, the anterolateral drawer test provoked almost twice the lateral talus displacement found with the anterior drawer test.

CLINICAL RELEVANCE

Allowing internal rotation of the ankle while testing for ankle instability may allow the examiner to detect more subtle degrees of ankle instability.

Posterolateral ankle ligament injuries affect ankle stability: a finite element study

BACKGROUND

We have already discovered 23 patients during the work of the outpatient department and operations whose unstable signs on the posterolateral ankle. The anterior drawer test demonstrated normal during the physical examinations while the spaces of the posterior tibiotalar joints increased in stress X-ray plain films. ATFL intact and posterolateral ligaments lax were found during operations too. It is important to make existence claims and illuminate the mechanism of posterolateral ankle instability.

METHODS

A finite element model of the ankle was established for simulating to cut off posterolateral ligaments in turn. Ankle movements with tibia rotation under load on five forefoot positions were simulated as well.

RESULTS

The difference values with tibia external rotation were negative, and the positive results occurred with tibia internal rotation. The tibia-talus difference values in some forefoot positions were 2 ~ 3 mm after PTFL together with CFL or/and PITFL were cut off. The tibula-talus difference values were 2.21 ~ 2.76 mm after both PTFL and CFL were cut off. The tibia-fibula difference values were small. The difference values increased by 2 ~ 5 mm after cutting off the PITFL.

CONCLUSIONS

Posterolateral ankle ligaments, especially CFL and PITFL, play a significant role in maintaining ankle stability. The serious injuries of both CFL and PITFL would affect posterolateral ankle stabilities. PITFL was important to subtalar joint stability.

In Vivo Talocrural Joint Contact Mechanics With Functional Ankle Instability

BACKGROUND

Functional ankle instability (FAI) may involve abnormal kinematics and contact mechanics during ankle internal rotation. Understanding of these abnormalities is important to prevent secondary problems in patients with FAI. However, there are no in vivo studies that have investigated talocrural joint contact mechanics during weightbearing ankle internal rotation. The objective of this study to determine talocrural contact mechanics during weightbearing ankle internal rotation in patients with FAI.

METHODS

Twelve male subjects with unilateral FAI (age range, 18-26 years) were enrolled. Computed tomography and fluoroscopic imaging of both lower extremities were obtained during weightbearing passive ankle joint complex rotation. Three-dimensional bone models created from the computed tomographic images were matched to the fluoroscopic images to compute 6 degrees of freedom for talocrural joint kinematics. The closest contact area in the talocrural joint in ankle neutral rotation and maximum internal rotation during either dorsiflexion or plantar flexion was determined using geometric bone models and talocrural joint kinematics data.

RESULTS

The closest contact area in the talus shifted anteromedially during ankle dorsiflexion-internal rotation, whereas it shifted posteromedially during ankle plantar flexion-internal rotation. The closest contact area in FAI joints was significantly more medial than that in healthy joints during maximum ankle internal rotation and was associated with excessive talocrural internal rotation or inversion.

DISCUSSION

This study demonstrated abnormal talocrural kinematics and contact mechanics in FAI subjects. Such abnormal kinematics may contribute to abnormal contact mechanics and may increase cartilage stress in FAI joints.

LEVEL OF EVIDENCE

Therapeutic, Level IV: cross-sectional case-control study.

Ankle Joint Contact Loads and Displacement With Progressive Syndesmotic Injury

BACKGROUND

Ligamentous injuries to the distal tibiofibular syndesmosis are predictive of long-term ankle dysfunction. Mild and moderate syndesmotic injuries are difficult to stratify, and the impact of syndesmosis injury on the magnitude and distribution of forces within the ankle joint during athletic activities is unknown.

METHODS

Eight below-knee cadaveric specimens were tested in the intact state and after sequential sectioning of the following ligaments: anterior-inferior tibiofibular, anterior deltoid (1 cm), interosseous/transverse (IOL/TL), posterior-inferior tibiofibular, and whole deltoid. In each condition, specimens were loaded in axial compression to 700 N and then externally rotated to 20 N·m torque.

RESULTS

During axial loading and external rotation, both the fibula and the talus rotated significantly after each ligament sectioning as compared to the intact condition. After IOL/TL release, a significant increase in posterior translation of the fibula was observed, although no syndesmotic widening was observed. Mean tibiotalar contact pressure increased significantly after IOL/TL release, and the center of pressure shifted posterolaterally, relative to more stable conditions, after IOL/TL release. There were significant increases in mean contact pressure and peak pressure along with a reduction in contact area with axial loading and external rotation as compared to axial loading alone for all 5 conditions.

CONCLUSION

Significant increases in tibiotalar contact pressures occur when external rotation stresses are added to axial loading. Moderate and severe injuries are associated with a significant increase in mean contact pressure combined with a shift in the center of pressure and rotation of the fibula and talus.

CLINICAL RELEVANCE

Considerable changes in ankle joint kinematics and contact mechanics may explain why moderate syndesmosis injuries take longer to heal and are more likely to develop long-term dysfunction and, potentially, ankle arthritis.

The role of the medial ligaments in lateral stabilization of the ankle joint: an in vitro study

PURPOSE

The deltoid ligament complex is known as medial stabilizer in the ankle against pronation/eversion. Lateral dual-ligament laxity often results in chronic ankle instability with recurring ankle sprain trauma. The goal of this study is to examine the lateral stabilizing role of the deltoid ligament complex against supination/inversion in case of existing lateral ligament instability.

METHODS

A torsion simulation was performed on 12 fresh human lower leg cadaver specimens in a loading frame and a specially designed mounting platform. The preset torsion between tibia and calcaneus was primarily set at 30° of internal rotation on specimen in plantar flexion and hindfoot inversion. The measured variable was the resisting torque recorded around mechanical tibial axis, which ensures stability in ankle sprain trauma. The first series of measurements were performed on healthy specimens and the following after transecting structures in following order: anterior talofibular ligament (ATFL) in combination with calcaneofibular ligament (CFL), followed by anterior tibiotalar ligament and posterior tibiotalar ligament and finally tibiocalcaneal ligament (TCL).

RESULTS

The combined lateral ATFL and CFL instability showed a decrease in the resisting torque, which ensures stability in ankle sprain trauma. Only a transection of TCL (superficial layer of deltoid ligament complex) with existing lateral dual-ligament instability results in a significant decrease in torque (p<0.0001).

CONCLUSION

The goal of the study was to provide the orthopaedic and/or trauma surgeon with quantitative data that may be referred to the substantial stabilizing effect of TCL against supination/inversion in the ankle joint in case of repetitive sprain trauma at a present lateral ligament lesion. Diagnostics of and treatment for lateral ligament instability need to consider the deltoid ligament complex,especially TCL in clinical routine.

Repair of the acute deltoid ligament complex rupture associated with ankle fractures: a multicenter clinical study

Controversy exists concerning the need for operative repair of the deltoid ligament during management of acute ankle fractures. The purpose of our report was to identify the indications for surgical intervention for deltoid ligament injury in the setting of ankle fractures. Furthermore, we aimed to elucidate the clinical outcomes after deltoid ligament repair in this setting. This was a multicenter study, involving 4 clinical institutions. From January 2006 to December 2011, 1533 ankle fractures underwent surgical intervention. Of this group, 131 deltoid ligament ruptures (8.55%) were identified and repaired operatively. Of the 131 patients, 74 were male (56.5%) and 57 were female (43.5%), with a mean age of 33.2 (range 16 to 63) years. The outcome measures included the clinical examination findings, radiographic findings, American Orthopaedic Foot and Ankle Society ankle-hindfoot scores, visual analog scale (VAS) scores, and Medical Outcomes Study Short Form 36-item questionnaire scores. All incisions healed primarily. A total of 106 patients were followed up for a minimum of 12 (range 12 to 72) months, with an average follow-up period of 27 months. The mean interval to fracture union was 14.5 (range 9 to 16) weeks. The mean American Orthopaedic Foot and Ankle Society ankle-hindfoot score at the latest follow-up visit was 91.4 (range 83 to 100) points. The mean visual analog scale score was 1.2 (range 0 to 6) points. The mean Short Form-36 score was 91.2 (range 80 to 96) points. Compared with the preoperative scores, all the 3 outcome measures had improved significantly postoperatively (p < .05). The postoperative stress radiographs did not reveal any ankle instability. None had evidence of post-traumatic arthritis of the ankle from the clinical examination and radiographs. A reasonable clinical evaluation and surgical repair was executed, with an appropriate repair technique chosen according to the site of deltoid ligament rupture. The results of the present multicenter study have shown that deltoid ligament rupture can be repaired in patients with an unstable medial ankle after fracture fixation and prevent ankle stabilization-related complications.

American Society of Biomechanics Clinical Biomechanics Award 2013: tibiofemoral contact location changes associated with lateral heel wedging--a weight bearing MRI study

BACKGROUND

Vertically open magnetic resonance imaging permits study of knee joint contact during weight bearing. Lateral wedging is a low cost intervention for knee osteoarthritis that may influence load distribution and contact. This study assessed the ability of feedback-assisted weight bearing magnetic resonance imaging to detect changes in tibiofemoral contact associated with lateral wedging.

METHODS

One knee in each of fourteen subjects with symptomatic knee osteoarthritis was studied, without specification of compartmental involvement. Knees were imaged during upright standing and at 20° knee flexion. Bilateral external heel wedges were used to provide non-wedged and 5° lateral wedging conditions. Computer modeling was used to measure the medial and lateral compartment contact patch center coordinates on the tibial plateau and the respective contact areas.

FINDINGS

Lateral heel wedging in flexion was associated with a significant anterior shift of the contact patch of the lateral femoral condyle. Changes with knee flexion were similar to previous reports: both medial and lateral contact centers moved posteriorly with flexion, and lateral condyle contact also moved laterally. Lateral condyle contact area significantly reduced with flexion, while lateral wedging did not significantly affect contact areas.

INTERPRETATION

In symptomatic knee osteoarthritis patients standing in knee flexion, weight bearing magnetic resonance imaging recorded an anterior shift of lateral condyle contact in response to lateral heel wedging. Future studies may investigate lateral wedging effects more specifically in candidates for this clinical intervention.

Anterior ankle impingement: diagnosis and treatment

Anterior ankle impingement is a common clinical condition characterized by chronic anterior ankle pain that is exacerbated on dorsiflexion. Additional symptoms include instability; limited ankle motion; and pain with squatting, sprinting, stair climbing, and hill climbing. Diagnosis is typically confirmed with plain radiographs. Nonsurgical management includes physical therapy, strengthening exercises, activity modification, bracing, and anti-inflammatory medication. Although arthroscopic treatment is sufficient in some patients, most require an open approach to address related pathology. We advocate aggressive range of motion as well as weight bearing postoperatively. Further study is needed to confirm current understanding of anterior ankle impingement and to better define treatment options and prevention strategies.