Mechanical Ankle Instability Patients Research Articles

Characteristics and predictors of muscle strength deficit in mechanical ankle instability

PurposeMuscle strength training is a common strategy for treating chronic ankle instability (CAI), but the effectiveness decreases for mechanical ankle instability (MAI) patients with initial severe ligament injuries. The purpose of this study was to investigate the characteristics and the potential predictors of muscle strength deficit in MAI patients, with a view to proposing a more targeted muscle strength training strategy.MethodsA total of 220 MAI patients with confirmed initial lateral ankle ligament rupture and a postinjury duration of more than 6 months were included. All patients underwent a Biodex isokinetic examination of the ankle joints of both the affected and unaffected sides. Then, the associations between the limb symmetry index (LSI) (mean peak torque of the injury side divided by that of the healthy side) and the patients’ sex, body mass index, postinjury duration, presence of intra-articular osteochondral lesions, presence of osteophytes and ligament injury pattern (i.e., isolated anterior talofibular ligament (ATFL) injury or combined with calcaneofibular ligament injury) were analysed.ResultsThere was significantly weaker muscle strength on the affected side than on the unaffected side in all directions (p < 0.05). The LSI in plantar flexion was significantly lower than that in dorsiflexion at 60°/s (0.87 vs 0.98, p < 0.001). A lower LSI in eversion was significantly correlated with female sex (0.82 vs 0.94, p = 0.016) and isolated ATFL injury (0.86 vs 0.95, p = 0.012). No other factors were found to be associated with muscle strength deficits.ConclusionMAI patients showed significant muscle strength deficits on the affected side, especially in plantar flexion. There were greater strength deficits in eversion in females and individuals with an isolated ATFL injury. Thus, a muscle strength training programme for MAI patients was proposed that focused more on plantar flexion training and eversion training for females and those with an isolated ATFL injury.

Increased ATFL-PTFL angle could be an indirect MRI sign in diagnosis of chronic ATFL injury.

Magnetic resonance imaging (MRI) has relatively low accuracy in diagnosing chronic anterior talofibular ligament (ATFL) injury. This study's purpose was to evaluate the angle between the ATFL and posterior talofibular ligament (PTFL) as a new indirect MRI sign of chronic ATFL injury in patients with mechanical ankle instability (MAI). This study included 200 participants: 105 patients with MAI and 95 patients seen at our institution for reasons unrelated to ankle instability. MR images of all 200 participants were reviewed. The ATFL-PTFL angle in the axial plane was measured and compared between groups. Receiver operating characteristic curves (ROC) were used to analyze ATFL-PTFL angles in participants with and without ATFL injury. The sensitivity and specificity of this method for diagnosing ATFL injury were calculated. The mean ATFL-PTFL angle was significantly larger among MAI patients than among control patients (81.5° ± 9.8° vs 75.2° ± 8.9°, respectively; P < 0.01). The area under the ROC was 0.789 (P < 0.01). The optimal cut-off point for diagnosing ATFL injury on the basis of the ATFL-PTFL angle was 79.0° (sensitivity 0.89, specificity 0.67). The ATFL-PTFL angle was significantly larger among MAI patients than among those without MAI. Increased ATFL-PTFL angle offers a new indirect MRI sign for diagnosing chronic ATFL injury. The ATFL-PTFL angle can be used not only to improve the accuracy of diagnosis of chronic ATFL injury, but also to evaluate the restoration of normal ankle joint geometry after lateral ligament reconstruction. III.

Impaired Balancing Function in Patients of Chronic Mechanical Ankle Instability

Category: Ankle Introduction/Purpose: Chronic ankle instability (CAI) is a disease entity commonly seen after ankle ligament injury. It is divided into mechanical ankle instability (MAI) and functional ankle instability (FAI), with different pathological conditions. The purpose of this study was to test the balancing ability of MAI and FAI patients. Methods: 30 CAI patients and 10 normal subjects were included according to the injury history, clinical symptom and MRI presentation. Stress tests were given under fluoroscopy to find out those with mechanical instability in CAI patients. Among them there were 18 MAI and 12 FAI patients. All patients were tested on a customized balancing ability assessment system developed by Shanghai Jiaotong University. Subjects were asked to stand on the platform for 30 seconds for both feet, 10 seconds for single foot, with eyes open. And 30 seconds for both feet, 5 seconds for single foot, with eyes closed. Each condition was tested for 3 trials and results were averaged. Parameters of balance like the swaying trajectory length and speed at both medial-lateral and anterior-posterior directions, the trajectory length per unit were obtained. Results were compared among three groups. Results: The MAI group presented significantly greater imbalance in both medial-lateral and anterior-posterior directions compared with that in the control group while standing on the single diseased foot, with eyes open or closed. While in the FAI group, no significant difference was found in postural sway compared with that in the control group. The MAI group presented significantly greater imbalance in both medial-lateral and anterior-posterior directions than the FAI group while standing on the single diseased foot with eyes open or closed. No significant difference in balancing was found of the contralateral ankle in the two groups. Conclusion: The balancing ability of MAI patients was impaired and then make them vulnerable to falling. Thus either balance training program or reconstructive surgery is needed to restore the balancing ability in those patients.

MRI Identification of the Fibular and Talus Position in Patients with Mechanical Ankle Instability.

Specific anatomic variations of the ankle mortise may be found in people with ankle instability. The purpose was to evaluate the fibular and talus position in subjects with mechanical ankle instability (MAI). In this study, MR images of 54 patients with MAI and 51 patients from the author's institution for reasons unrelated to ankle instability were reviewed. The position of the fibular in relation to the talus (axial malleolar index, AMI) and medial malleolus (intermalleolar index, IMI) were evaluated at the axial plane. Meanwhile, the rotation of the talus was measured and calculated using a new index, the Malleolar Talus Index (MTI), which is measured in relation to the medial malleolar. The results showed that the AMI in the MAI patients increased significantly when compared to that in the control group. However, there was no statistically significant difference in the IMI between instability and control groups. The MTI increased significantly in the MAI patients when compared to that in the control group. The conclusion was that the patients with MAI have more of an internally rotated talus than a variation of fibular position.

The Effect of Lateral Ankle Ligament Repair in Muscle Reaction Time in Patients with Mechanical Ankle Instability

Studies have shown that functional ankle instability can result in prolonged muscle reaction time. However, the deficit in muscle reaction time in patients with mechanical ankle instability (MAI) and the effect of lateral ankle ligament repair on muscle reaction time are unclear. The purpose of this study was to identify the deficit in muscle reaction time, and to evaluate the role of lateral ligament repair in improving muscle reaction time in MAI patients. Sixteen MAI patients diagnosed with lateral ankle ligament tears by ultrasonography and magnetic resonance imaging underwent arthroscopic debridement and open lateral ankle ligament repair with a modified Broström procedure. One day before the operation, reaction times of the tibialis anterior and peroneus longus muscles were recorded following sudden inversion perturbation while walking on a custom walkway, and anterior drawer test (ADT) and American Orthopaedic Foot and Ankle Society (AOFAS) scale score were evaluated. Six months postoperatively, muscle reaction time, ADT and AOFAS scale score were reevaluated, and muscle reaction times in 15 healthy controls were also recorded. Preoperatively, the affected ankles in the MAI group had significantly delayed tibialis anterior and peroneus longus muscles reaction times compared with controls. Six months after the operation, median AOFAS scale scores were significantly greater than preoperatively, and ADT was negative in the MAI group. However, the affected ankles in the MAI group showed no difference in muscle reaction time compared with preoperative values. MAI patients had prolonged muscle reaction time. The modified Broström procedure produced satisfactory clinical outcomes in MAI patients, but did not shorten reaction times of the tibialis anterior and peroneus longus muscles.

Difference in Postural Control Between Patients With Functional and Mechanical Ankle Instability

Lateral ankle sprain is one of the most common injuries. Since the structural and pathological differences in mechanical ankle instability (MAI) and functional ankle instability (FAI) may not be the same, it may be better to treat these as separate groups. The purpose of this study was to compare the difference in postural sway between MAI and FAI in patients with chronic ankle instability (CAI). Twenty-six patients with CAI and 14 healthy control participants were included in the study. The CAI patients were subdivided into MAI (15 patients) and FAI (11 patients) groups. Patients who were diagnosed with lateral ankle ligaments rupture by magnetic resonance imaging and ultrasonography were assigned to the MAI group. All participants performed single-limb postural sway tests 3 times on each leg with eyes closed and open. The average distances from the mean center of pressure position in the mediolateral and anteroposterior directions were recorded and compared among the 3 groups. The unstable ankles in the MAI group showed significantly greater postural sway in the anterior, posterior, and medial directions compared with those in the control group with eyes closed. With eyes open, significantly greater postural sway was found in the anterior direction. In the FAI group, no difference was found in postural sway compared with those in the control group. The MAI group showed significantly greater postural sway in the anterior direction compared with the FAI group with eyes closed and open. No significant difference in postural sway was found between the unstable and stable ankles in the MAI or FAI groups, with or without vision. Patients with MAI have deficits in postural control, especially in anterior-posterior directions. However, no difference was found in postural sway in patients with FAI compared with healthy people. As MAI patients suffer from deficits in postural control, balance training should be applied in those patients. In addition, special training should also include the contralateral side after a unilateral ankle ligament injured.