Biomechanical analysis of the ankle anterior drawer test for anterior talofibular ligament injuries

The effect of sectioning the anterior talofibular ligament on the load-displacemnt behavior of the ankle was evaluated in vitro during the anterior drawer test using the flexibility approach. Controlled forces were applied across the ankle joint in the anterior-posterior direction, and the resulting displacements were measured at four flexion angles (10° of dorsiflexion, neutral, and 10° and 20° of plantar flexion). The anterior talofibular ligament then was sectioned, and the anterior-posterior loadings were repeated at the four flexion angles. Two parameters were developed to describe the nonlinear load-displacemnt response of the ankle joint: neutral zone laxity (joint displacement between ± 2.5 N) and flexibility (a measure of the nonlinear load-displacement response of the ankle between 10 and 50 N of anterior drawer loading). After sectioning the anterior talofibular ligament, significant increases in neutral zone laxity were observed at all angles of ankle flexion. The largest increases in neutral zone laxity were found with the ankle in 10° of plantar flexion (76.3% increase) and 20° of plantar flexion (89.7% increase). After sectioning the ligament, a significant increase (19.3%) in flexibility of the ankle was observed at 10° of dorsiflexion, but no change in flexibility was observed with the ankle in the neutral and plantar flexed positions. These findings indicate that anterior drawer testing of the anterior talofibular ligament-deficient ankle between 10° and 20° of plantar flexion results in the largest increase in neutral zone laxity compared with the normal ankle with intact ligaments. They also suggest that an excessive magnitude of force during clinical application of the anterior drawer examination may not be needed to diagnose disruption of the anterior talofibular ligament.     

Rotational Instability after Anterior Talofibular and Calcaneofibular Ligament Section: The Experimental Basis for the Ankle Pivot Test

The clinical diagnosis of the anterior talofibular ligament (ATFL) rupture is based on the findings from the medical history and the anterior drawer test, a maneuver that allegedly pushes the talus and rearfoot anteriorly, although with great variability in its sensitivity. We consider that an ATFL rupture is best evaluated by a rotational vector (i.e., a pivot test) owing to the uncompromised medial ligaments that will block any pure anterior translation of the talus underneath the tibia. We idealized a constrained ankle cadaver model that only allows talar movements in the axial plane. Our hypothesis was that progressive sectioning of the lateral ankle ligaments in this model would cause a progressive and significant angular laxity in internal rotation. Our results showed 3.67 degrees ± 1.2 degrees of talus rotational laxity in the intact ankle, 9.6 degrees ± 3.2 degrees after ATFL sectioning, and 13.43 degrees ± 3.2 degrees after ATFL and calcaneofibular ligament sectioning, indicating almost threefold increase in internal talocrural rotation after single ATFL sectioning and an almost fourfold increase after double (ATFL and calcaneofibular ligament) sectioning. We consider this evidence of rotational ankle laxity to be a major step in defining the correct movement to diagnose an ATFL rupture and propose a new term to avoid further inconsistencies and variability, “the pivot test.”     

Effect of distal fibular resection on ankle laxity

Ten cadaver specimens were used to study the effect of distal fibular resection and ligamentous repair on ankle laxity. The distal fibula was resected sequentially at three levels. Talar tilt and anterior drawer were measured on stress radiographs after resection and then after ligament repair. Sequential resection of the distal fibula caused a progressive increase in talar tilt and anterior drawer at each cut level (p < 0.5), regardless of whether the ligaments were repaired or not. Ligament repair significantly decreased talar tilt at cuts above the ATFL insertion and decreased anterior drawer at cuts at the tibiotalar level, but these values did not approach control values.     

The contribution of the anterior talofibular ligament to ankle laxity

The motion responses of thirty fresh-frozen cadaver tibiotalar joints were measured for applied anterior-posterior force, inversion-eversion moment, and internal-external rotary torque. The load-motion response curves obtained after sectioning the anterior talofibular ligament were compared with those for intact specimens in three positions of flexion of the ankle. Laxity of the intact ankle was shown to be dependent on flexion position; dorsiflexion was consistently the position of least laxity, reflecting the effects of talar geometry and its articulation with the tibiotalar syndesmosis. Section of the anterior talofibular ligament produced significant increases in laxity for all modes tested. Total anterior-posterior laxity increased by 4.3 millimeters in dorsiflexion, which was the position of maximum change. In contrast, the greatest increases in total inversion-eversion laxity (5.2 degrees) and total internal-external rotation laxity (10.8 degrees) were recorded in plantar flexion.     

Effects of lateral ligament sectioning on the stability of the ankle and subtalar joint

Patients with subtalar joint instability are often diagnosed with ankle instability. Only after a prolonged period of time in which a patient does not improve after treatment for ankle instability is subtalar joint instability considered. To develop a clinically relevant method to diagnose subtalar joint instability, the kinematics of the simulated unstable subtalar joint were examined. A 6 degree‐of‐freedom positioning and loading device was developed. Plantarflexion/dorsiflexion, inversion/eversion, and internal/external rotation were applied individually or as coupled motions along with an anterior/posterior drawer. Kinematic data were collected from sensors attached to the calcaneus, talus, and tibia by keeping all the ligaments intact, and by serially sectioning anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), cervical ligament, and talocalceneal interosseous ligament. Kinematic results were reported using Euler angles. The ATFL and CFL contributed talocrural instability, similar to previous studies. The interosseous ligament was the greatest contributor to subtalar joint stability. The hindfoot motion (calcaneus relative to tibia) showed significant increases in motion when the ankle and/or subtalar joint was made to be unstable. Therefore, it is difficult to diagnose subtalar joint instability on physical examination alone. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29: 1459–1464, 2011     

Analysis of ankle-hindfoot stability in multiple planes: an in vitro study

BACKGROUND: It is necessary to have an understanding of ankle and hindfoot motion and stability to accurately diagnosis and treat ankle-hindfoot disorders. METHODS: We devised an ankle ligament testing apparatus to more critically determine ankle stability in all planes with a constant rotational force applied (inversion, eversion, internal rotation, external rotation) throughout the range of sagittal plane motion in 13 cadaver specimens. Three-dimensional kinematics were determined with a magnetic tracking device. RESULTS: With inversion force applied, calcaneal-tibial inversion was greatest in maximal plantarflexion (mean 22.1 +/- 6.0 degrees) and gradually decreased with dorsiflexion, which indicated that the ankle had the most inversion instability in plantarflexion. With eversion force applied, calcaneal-tibial eversion gradually increased with increasing dorsiflexion to 12.7 +/- 7.4 degrees indicating that the most eversion instability was in dorsiflexion. With internal rotation force applied, calcaneal-tibial internal rotation from plantarflexion to neutral ankle position increased. With external rotation force application, external rotation from neutral to maximal dorsiflexion increased. CONCLUSIONS: Ankle laxity was not constant but varied depending on the plantarflexion-dorsiflexion position and the direction of the applied force. The degree of ankle laxity was greater with inversion and internal rotation torque. Variation in laxity between specimens was observed, consistent with previous reports. These data indicate that the ankle is less stable in plantarflexion when inversion and internal rotation forces are applied. This may explain why the lateral ankle ligaments are most prone to injury in this position. The ankle was less stable in dorsiflexion when eversion and external rotation forces were applied. This is consistent with the observation that deltoid ligament injuries occur in the neutral to dorsiflexion position. The study demonstrates the importance of examining patients with suspected ankle ligament injuries in several ankle positions. The ankle testing device has potential application for in vivo testing of patients with suspected ankle ligament instability.     

Experimental instability of the ankle. A radiographic investigation

For determination of the optimal position in examining the ankle joint for anterior drawer sign and talar tilting, 12 legs freshly amputated above the knee were radiographically examined after successive transection of the lateral ankle ligaments in three different sequences. Apparatuses secured the position of the ankle joint in 25 degrees of inward rotation and 10 degrees and 30 degrees, respectively, of plantarflexion. Examination for anterior drawer sign gave significantly greater displacement with the foot in 10 degrees than with the foot in 30 degrees of plantarflexion and was most pronounced after the cutting of the anterior talofibular ligament. Examination for talar tilt gave a non-significantly greater displacement at 10 degrees of plantarflexion, except when cutting both the posterior talofibular and the anterior talofibular ligament. Isolated cutting of the calcaneofibular ligament gave only little displacement irrespective of the method used. Radiographic examination should be performed with 10 degrees of plantarflexion to obtain maximal displacement and 25 degrees of inward rotation of the leg to obtain a free ankle mortise in the anteroposterior projection and concentric arcs of the joint surfaces in the side projection.     

Simultaneous strain measurement with determination of a zero strain reference for the medial and lateral ligaments of the ankle

The strain changes of the central part of the anterior talofibular ligament (ATFL), the posterior talofibular ligament (PTFL), the calcaneofibular ligament (CFL), and the tibiocalcaneal ligament (TCL) were measured simultaneously for a full range of ankle motion. Twelve fresh frozen amputated ankles were used. To measure the strain changes of the ligaments, a Galium-Indium-filled silastic strain transducer was implanted in the center of each ligament. The zero strain reference was determined immediately after the measurement of strain changes in five of the 12 ankles by tensile testing of each bone-ligament-bone preparation. The maximum strain change of the ATFL, the PTFL, the CFL and the TFL were 7.9%, 5.9%, 5.3% and 5.2%, respectively. The ATFL was elongated in plantar flexion and shortened in dorsiflexion. The PTFL and the CFL were shortened in plantar flexion and elongated in dorsiflexion. The TCL was the longest around the neutral position and became shorter in planter flexion and dorsiflexion. The results showed that the ATFL was taut in plantar flexion over 16.2 degrees, the PTFL and the CFL were taut in dorsiflexion over 18 degrees and 17.8 degrees respectively, and the TCL was taut between 9.5 degrees of dorsiflexion and 9.5 degrees of plantar flexion. The length change pattern was different among the ankle ligaments, although there was only a slight difference between that of the PTFL and the CFL. This study provides fundamental data useful in studying ankle ligament reconstruction.     

Instability of the hindfoot after lesion of the lateral ankle ligaments: investigations of the anterior drawer and adduction maneuvers in autopsy specimens

The mobility patterns in the tibiotalocalcaneal joint complex with a solitary lesion of the anterior talofibular ligament (ATL) and a combined lesion of the ATL and calcaneofibular ligament (CFL) were studied in 22 human lower-extremity autopsy specimens mounted in a kinesiologic testing device. A solitary lesion of the ATL increased the anteroposterior (AP) laxity in the ankle joint in the entire range of flexion, with a maximum median of 3.1 mm in neutral flexion. Further cutting of the CFL increased AP laxity most obviously in dorsiflexion. A solitary lesion of the ATL resulted in a minor instability in adduction, whereas further lesion to the CFL increased adduction in the entire range of flexion, with a maximum median of 14.2 degrees in dorsiflexion. The anterior drawer maneuver can reveal a combined lesion of the ATL and CFL if performed with the tibiotalocalcaneal joint complex in dorsiflexion. Significant clinical instability in adduction will only take place when a combined lesion of the ATL and CFL is present.     

不同踝关节外侧韧带重建术的有限元比较

[目的]通过有限元分析的方法研究不同踝关节外侧韧带重建术对踝关节稳定状态的影响。[方法]选取1例32岁健康男性志愿者的踝关节三维CT数据,构建骨骼的实体模型。设计正常对照模型、单韧带重建模型、Y形重建模型、双隧道重建模型。网格划分、定义材料力学属性及接触关系。在踝关节中立位、跖屈20°、背伸10°三种状态添加150 N牵引力模拟前抽屉试验,1.7 N·m内旋扭矩模拟跟骨内翻试验。[结果]ATFL的Von Mises应力在中立位和跖屈20°位距,4个模型间差异无统计学意义(P>0.05),但背伸10°位单韧带重建模型和双隧道重建模型的Von Mises应力显著小于对照模型和Y形重建模型,差异有统计学意义(P<0.05)。内翻载荷下,CFL的Von Mises应力双隧道重建模型、Y形重建模型和对照模型之间差异无统计学意义(P>0.05)。在前抽屉应力下,距骨的前移距离在中立位和跖屈20°位,4模型之间差异无统计学意义(P>0.05),而在背伸10°位,Y形重建模型和对照模型均显著小于单韧带重建模型和双隧道重建模型(P<0.05)。内翻应力下,在中立位、跖屈20°位、背伸10°位,单韧带重建模型的距骨倾斜度均大于其他三个模型(P<0.05),而对照模型、Y形重建模型、双隧道重建模型差异无统计学意义(P>0.05)。[结论]双隧道和Y形重建踝关节外侧复合体的稳定性优于单纯重建距腓前韧带,而Y形重建作为一种功能解剖重建优于双隧道重建。     

Detecting Ankle Instability With an Instrumented Ankle Arthrometer: An Experimental Study

A new instrumented device was developed to quantify ankle joint stability during an anterior talar drawer test. The aim of the present study was to validate this device comparing bone kinematics with arthrometer measurement outcomes. An anterior talar drawer test was performed with 14 cadaver legs using a custom instrumented ankle arthrometer. Using clusters of bone‐pin markers, the relative three‐dimensional movement of calcaneus, talus, and fibula was simultaneously measured. Anterior drawer test was applied on the intact foot and after sequentially sectioning the anterior talofibular ligament, the calcaneofibular ligament, and the posterior talofibular ligament. Cutting the anterior talofibular ligament caused a significant increase in bone‐pin measured anterior translations of calcaneus and talus as well as in the anterior translation of the arthrometer. Analysis of receiver operating characteristic curves indicates a fair to good ability to discriminate between the intact and the sectioned conditions with the arthrometer. Distal distraction, inversion, and internal rotation movements were observed when two and three ligaments were cut. Results revealed that the ankle arthrometer was sensitive to detect changes in bone‐to‐bone movements during an anterior talar drawer test, when the anterior talofibular ligament was sectioned. Presumably due to movements in additional planes of motion, the arthrometer was not able to differentiate between situations with one or more ligaments cut. In conclusion, the instrumented anterior talar drawer tester may augment current procedures in assessing ankle instability primarily caused by ruptures of the anterior talofibular ligament. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2019–2026, 2019     

Narrowing the Normal Range for Lateral Ankle Ligament Stability with Stress Radiography

Stress radiographs are commonly performed to evaluate lateral ankle ligament stability; however, little agreement exists on the physiologic limits obtained from the anterior drawer and talar tilt stress tests. Published studies have reported the normal range for the anterior drawer test to be 3 to 10 mm and the normal range for the talar tilt test to be 0° to 23° for the uninjured ankle, leading to inconsistent interpretation. The primary objective of the present study was to narrow the threshold for the diagnosis of ankle ligament injury using stress radiographs by refining the values seen in the normal ankle. An improved understanding of normal ankle motion could allow for a more accurate determination of ligament injury using stress imaging. Conducted in a simplified, yet reproducible, manner, we hoped the present study would draw a parallel with generalized use in an office setting and would allow physicians the ability to more effectively diagnose ankle ligament injury. Bilateral radiographic images of anterior drawer and talar tilt stress tests were taken of 50 participants (100 ankles) with no history of ankle fracture or surgical intervention for ankle instability. Participants with a previous ankle sprain were later excluded from the result computations. Factors such as patient age and gender were evaluated. In the final analysis, 46 participants (76 ankles) were included, with a mean anterior drawer test result of 2.00 mm ± 1.71 mm and talar tilt test result of 3.39° ± 2.70° in the normal ankle. The results of the present study suggest that stress radiographs for lateral ankle stability can be performed in a simple and reliable manner. These results also support a much lower threshold for the diagnosis of lateral ankle injury than previously reported.     

Lateral ligament reconstruction with allograft in patients with severe chronic ankle instability

Introduction

Chronic ankle instability is a condition of perception of giving way and persistent pain usually following multiple ankle sprains. In case of severe joint laxity, surgical treatment with reconstruction of the lateral ligamental complex is recommended. The aim of this study was to evaluate the functional outcome of patients treated with lateral ligament reconstruction with allograft for severe chronic lateral ankle instability.

Materials and methods

We performed a retrospective cohort study of ten patients who underwent allograft external non-anatomic ligamentoplasty for severe chronic lateral ankle instability between 2009 and 2011, with an average follow-up of 16.3 months (SD 8.2). Median age at surgery was 29 years (range 25–35). All patients presented both ATFL and CFL lesion. Patients were evaluated using American Orthopaedic Foot and Ankle Society score, Karlsson–Peterson score, Tegner activity level, Sefton stability scale, and objective examination comprehending range of motion, anterior drawer sign and talar tilt test. Telos stress equipment was used for pre- and post-operative radiographic laxity testing.

Results

Follow-up examination at an average of 16.3 months (SD 8.2) after surgery showed significant improvement of all variables compared to pre-operative values (p < 0.001). Most patients rated their outcome as good/excellent. Telos stress radiographs documented improvement in joint stability.

Conclusions

Lateral ligament reconstruction with allograft represents a valid treatment option in patients with severe chronic lateral ankle instability.     

An analysis of the function of the posterior talofibular ligament

The function of the posterior talofibular ligament was studied using an apparatus which subjected the ankle joint to a measured torque and allowed the simultaneous recording of rotatory movements in two planes. Thirty osteoligamentous preparations of ankle joints were examined, half in the sagittal and horizontal planes and the remainder in the sagittal and frontal planes. Successive section of the lateral collateral ligaments was performed, including, in particular, selective division of the short and long fibres of the posterior talofibular ligament. The function of this ligament was investigated in combination with the other two collateral lateral ligaments, with the calcaneofibular ligament alone, and finally as the only remaining intact ligament. The posterior talofibular ligament plays only a supplementary role in ankle stability when the lateral ligament complex is intact. After rupture of the anterior talofibular and the calcaneofibular ligaments, however, the short fibres of the posterior ligament restrict internal and external rotation, talar tilt, and dorsiflexion, while its long fibres inhibit only external rotation, talar tilt, and dorsiflexion. As the posterior talofibular ligament has no independent stabilizing function in the intact ankle joint, an isolated rupture of this ligament is unlikely.     

Rekonstruktion des Au?enbandapparats mittels Kniebeugesehnentransplantat bei chronischer Au?enbandinstabilit?t des OSG

Objective

Reconstruction of the anterior talofibular (ATFL) and calcaneofibular (CFL) ligament in patients with chronic lateral ankle instability.

Indications

Symptomatic chronic lateral ankle instability.

Contraindications

Bony malalignment, advanced arthritic changes of the ankle joint, diabetic foot syndrome.

Surgical technique

Reconstruction of the ATFL and CFL with a free gracilisor or semitendinosus tendon graft through a V-shaped tunnel at the insertion site of the ATFL on the talar neck as well as a transfibular tunnel directed anterior to posterior through the fibula tip to a blind ending tunnel in the calcaneus at the insertion site of the CFL. Insertion of the graft through the talar tunnel, passing both graft ends through the fibular tunnel to the calcaneus. Fixation with a bioabsorbable screw.

Postoperative management

Short leg cast for 10?C14?days and partial weight-bearing. Afterwards ankle brace for 6?weeks and functional physical therapy.

Results

From December 2003 to August 2005, reconstruction of the ATFL and CFL with a hamstring tendon autograft was performed in 20 patients with chronic lateral instability of the ankle joint. All patients were evaluated after a mean follow-up time of 1.8?years (15?C36?months). Clinical evaluation referred to the AOFAS score. Stress radiography was performed for objective assessment of lateral ankle stability. Postoperatively 19 of 20 patients reported good subjective stability with no further ankle sprains. The mean postoperative AOFAS score was 92 of 100 points (72?C100). Stress radiography showed a significant reduction of both lateral ankle instability and talar tilt.     

Radiological Diagnosis of Lateral Ligament Lesion of the Ankle: A Comparison Between Talar Tilt and Anterior Drawer Sign

In a prospective study of 244 patients with ankle lesions a comparison between the talar tilt and the anterior drawer sign was made, leading to the following conclusions

Ligament lesions which are not disclosed by the talar tilt examination may be diagnosed by the anterior drawer sign. The anterior drawer sign cannot replace the talar tilt examination, or vice versa. The two methods are complementary. It is not possible to differentiate between an isolated lesion of the anterior talofibular ligament and a combined lesion of the anterior talofibular and the calcaneofibular ligaments by the two methods.     

Ankle ligament tensile forces at the end points of passive circumferential rotating motion of the ankle and subtalar joint complex

BACKGROUND: Ankle ligament injuries and instability are commonly observed. Knowledge of the relationship between the foot position and tensile forces of the ankle ligaments could be useful for treatment of ankle ligament disorders. The aim of this study was to measure the tensile forces of the ankle ligaments at the end points of passive circumferential rotating motion of the ankle and subtalar joint complex in various foot positions. METHODS: Ligament tensile forces of the anterior talofibular (ATF), calcaneofibular (CF), posterior talofibular (PTF), and tibiocalcaneal (TC) ligaments were measured simultaneously in eight cadaver specimens, with a force probe in each ligament in a custom-made ankle ligament testing device. Weights of 0.5 kg and 1 kg were applied to the foot through a loading arm to provide axial compression and a bending moment to the foot and ankle. The position of the loading arm was changed circumferentially in 10-degree increments. RESULTS: Maximal tensile force in the ATF ligament was observed in supination with plantarflexion (108 +/- 62.8 N at 0.5 kg and 130 +/- 39.1 N at 1 kg). The maximal tensile force in the CF ligament was observed in pronation with plantarflexion (68 +/- 48.6 N at 0.5 kg and 135 +/- 92.9 N at 1 kg). The maximal tensile force in the PTF ligament was observed in dorsiflexion (131 +/- 80.1 N at 0.5 kg and 109 +/- 36.3 N at 1 kg). The maximal tensile force of the TC ligament was observed in pronation with plantarflexion (49.0 +/- 80.1 N at 0.5 kg and 67.4 +/- 69.6 N at 1 kg). Relatively high magnitudes of tensile force were observed in the ankle ligaments, and the peak forces were related to the anatomic position of individual ligaments. CONCLUSIONS: The ATF ligament has an important role in the supination position in plantarflexion, CF and TC ligaments also are important for pronation in plantarflexion, and the PTF is an important stabilizer in dorsiflexion. This study provides baseline information for further research related to ligament instability and reconstruction operations.     

The effect of partial deltoid ligament injuries on the external rotation stability: A cadaveric study

BackgroundThe anterior and posterior part of the deltoid ligament have different functions during ankle flexion motion. Partial ligament injuries have been demonstrated in previous clinical reports. However, the efficacy of external rotation stress test in partial injured cases is unavailable till now.MethodsThirty-two fresh cadaveric specimens were included and allocated into two destabilization groups. In the first group, the anterior portion of deltoid ligament (DL) and syndesmotic ligament were sequentially severed, while in the second group, the posterior portion of DL and syndesmotic ligament were sequentially severed. Mortise view radiographs were taken after each destabilization stage when the ankles were placed at plantarflexion and dorsiflexion positions and stressed in standard external rotation force. The medial clear space (MCS) and talar tilt (TT) angle were measured and compared among different destabilization stages.ResultsWhen the ankles were placed at neutral position, the TT significantly increased in all destabilization stages. The MCS significantly increased after the partial deltoid ligament ruptures only with presence of syndesmotic ligament injuries. There was no significant difference of MCS at plantarflexion for all stages of destabilization if the anterior portion of DL is preserved. Similarly, no significant increase of MCS was detected at dorsiflexion if the posterior portion of DL and posterior inferior tibiofibular ligament are intact.ConclusionPartial DL rupture causes ankle rotational instability at different ankle joint positions, especially when combined with syndesmotic injuries. The neutral position is recommended for diagnosis of partial DL ruptures under external rotation stress.     

Comparison Between the Simultaneous Reconstructions of the Anterior Talofibular Ligament and Calcaneofibular Ligament and the Single Reconstruction of the Anterior Talofibular Ligament for the Treatment of Chronic Lateral Ankle Instability

This study aimed to evaluate the procedures of reconstruction surgery for chronic lateral ankle instability. We compared single anterior talofibular ligament reconstruction to simultaneous reconstructions of the anterior talofibular and calcaneofibular ligaments. From 2015 to 2019, 14 consecutive patients diagnosed with chronic lateral ankle instability underwent arthroscopic anterior talofibular ligament reconstruction with or without calcaneofibular ligament reconstruction after conservative treatment. Seven patients underwent single anterior talofibular ligament reconstruction (group AT), and 7 patients underwent simultaneous reconstructions of the anterior talofibular ligament and calcaneofibular ligament (group AC). The Japanese Society for Surgery of the Foot scale scores and Karlsson scores significantly improved in all patients 1 year postoperatively. The radiographic measurement of the talar tilt angle and the talar anterior drawer distance at 1 year after surgery were also significantly improved compared to preoperative values. The postoperative talar tilt angle was significantly greater in group AT (median 6°, range 3°-7°) than that in group AC (median 3°, range 2°-5°; p = .038). The postoperative talar anterior drawer distance, Japanese Society for Surgery of the Foot scale score, and Karlsson score were not significantly different between the 2 groups.We found that although the clinical outcomes after the anterior talofibular ligament reconstruction with or without the calcaneofibular ligament reconstruction for chronic lateral ankle instability were good, instability of the talar tilt angle at 1 year postoperatively in patients who underwent single anterior talofibular ligament reconstruction was greater than that in patients who underwent simultaneous anterior talofibular and calcaneofibular ligament reconstructions.     

Tibiotalar motion--effect of fibular displacement and deltoid ligament transection: in vitro study

The purpose of this study was to quantify tibiotalar translation and rotation under various stages of fibular displacement and injury to the syndesmotic and deltoid ligaments. Ten unpaired specimens amputated below the knee were studied using an unconstrained testing apparatus. The specimens were moved through a dorsiflexing and plantarflexing arc of 55 degrees (20 degrees dorsiflexion and 35 degrees plantarflexion). Dorsiflexion of the intact lower leg was associated with an average of 4.2 degrees of external talar rotation, and plantarflexion was associated with an average of 1.4 degrees of internal talar rotation. Fibular osteotomy and displacement of the distal fibular fragment did not change the talar rotation significantly. Additional transection of the deltoid ligament, however, decreased external talar rotation significantly, to 1.4 degrees, and decreased talar internal rotation to 0.6 degrees. Talar shift was not affected in dorsiflexion or plantarflexion by fibular fracture, displacement of the distal fibular fragment, or transection of the deltoid ligament. These data may suggest that in dorsiflexion or plantarflexion, an intact lateral malleolus is not necessary for physiological talar tracking. They further suggest that in a fibular fracture with a significant injury to the deltoid ligament, healing of the ligament at its resting length is crucial to restoring physiological talar rotation.