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Biomechanical characteristics of human ankle-joint muscles.

Equivalent biomechanical characteristics of human ankle-joint muscles have been determined by impact and vibration tests. The estimate of the stiffness and damping coefficients has yielded, respectively, (2.67 +/- 0.48) X 10(4) N X m-1 and (811.58 +/- 201.3) N X s X m-1 by impact actions, n = 126; (1.49 +/- 0.35) X 10(4) N X m-1 and (430.1 +/- 36.1) N X s X m-1 -by vibration actions, n = 7. The characteristics of the ankle-joint muscles of subjects representing different kinds of sports have proved to be different.

Ankle Joint↗

Diabetic sensory neuropathy effect on ankle joint movement perception.

OBJECTIVE: To determine if diabetic subjects with lower extremity cutaneous sensory neuropathy also have a loss of ankle joint movement perception. The strength of association between measurements of ankle joint movement perception and measures of cutaneous sensory function was also investigated. DESIGN: Diabetic subjects with and without sensory neuropathy and individuals without diabetes participated in this study. SETTING: All subjects were community-living individuals. PARTICIPANTS: Fifty-one subjects, ages 40 to 68. Seventeen of the 34 subjects with diabetes had significant distal sensory neuropathy as determined by cutaneous perception of mechanical vibration. All individuals without diabetes were volunteers from the community. Most subjects with diabetes were recruited through direct referral from their physicians. INTERVENTIONS: Ankle joint movement perception threshold (JMPT) was assessed using a device designed for this study. Cutaneous sensory function under both halluces was measured for vibration perception using a vibrometer and for touch-pressure perception using Semmes-Weinstein monofilaments. MAIN OUTCOME MEASURES: Ankle JMPTs (degrees) were compared to measurements of cutaneous vibration perception (volts) and touch-pressure perception (monofilaments force ratings). RESULTS: Diabetic subjects with cutaneous sensory neuropathy demonstrated a significant loss of ankle movement perception (p < .01). Correlation between JMPT and cutaneous sensory tests ranged from Spearman's rank r = .43 to .67. CONCLUSIONS: Although individuals with cutaneous sensory loss secondary to diabetic neuropathy also demonstrated loss of movement perception at the ankle, the relatively low explained variance between the two types of assessment (18% to 45%) indicates that the severity of ankle joint movement perception deficits cannot be directly implied from cutaneous sensory tests.

Adult↗

A six-degrees-of-freedom instrumented linkage for measuring the flexibility characteristics of the ankle joint complex.

Diagnosis of ligament injuries to the ankle joint complex is a difficult clinical problem which relies primarily on manual physical examination and on radiographic evaluations. In an attempt to develop a reliable, quantitative diagnostic tool for such injuries we developed a six-degrees-of-freedom instrumented linkage (Ankle Flexibility Tester-AFT) capable of measuring the flexibility characteristics of the ankle joint complex in vivo. The unique non-serial structure of this linkage was such that these characteristics were recorded directly in an ]anatomical coordinate system which enhanced clinical interpretation. The goal of the present study was to develop this linkage and to test its accuracy and its test-retest reliability. The positional accuracy of the AFT was measured and was found to be better than 0.5 mm for translation and 1.2 degrees for rotations. The results obtained from a study conducted on two cadaveric specimens indicate negligible effect of loading rate on the flexibility characteristics within the range of possible manually applied loads. Finally, the reliability of the AFT was examined from test-retest studies conducted on a total of thirteen young healthy volunteers. The intraclass correlation coefficient (ICC), calculated from the test-retest data, indicated a reliability higher than 0.85. It was concluded that the high reliability and accuracy of the AFT, its simplicity of operation, the easy alignment procedure, the on-line load-displacement results, and the elimination of complex data processing render this device suitable for use in the clinic as well as in the research laboratory.

Ankle Injuries↗

In vivo determination of the anatomical axes of the ankle joint complex: an optimization approach.

This study investigates the feasibility of a subject-specific three-dimensional model of the ankle joint complex for kinematic and dynamic analysis of movement. The ankle joint complex was modelled as a three-segment system, connected by two ideal hinge joints: the talocrural and the subtalar joint. A mathematical formulation was developed to express the three-dimensional translation and rotation between the foot and shank segments as a function of the two joint angles, and 12 model parameters describing the locations of the joint axes. An optimization method was used to fit the model parameters to three-dimensional kinematic data of foot and shank markers, obtained during test movements throughout the entire physiological range of motion of the ankle joint. The movement of the talus segment, which cannot be measured non-invasively, is not necessary for the analysis. This optimization method was used to determine the position and orientation of the joint axes in 14 normal subjects. After optimization, the discrepancy between the best fitting model and actual marker kinematics was between 1 and 3 mm for all subjects. The predicted inclination of the subtalar joint axis from the horizontal plane was 37.4 +/- 2.7 degrees, and the medial deviation was 18.0 +/- 16.2 degrees. The lateral side of the talucrural axis was directed slightly posteriorly (6.8 +/- 8.1 degrees), and inclined downward by 7.0 +/- 5.4 degrees. These results are similar to previously reported typical results from anatomical, in vitro studies. Reproducibility was evaluated by repeated testing of one subject, which resulted in variations of about one-fifth of the standard deviation within the group, the inclination of the subtalar joint axis was significantly correlated to the arch height and a radiographic 'tarsal index'. It is concluded that this optimization method provides the opportunity to incorporate inter-individual anatomical differences into kinematic and dynamic analysis of the ankle joint complex. This allows a more functional interpretation of kinematic data, and more realistic estimates of internal forces.

Algorithms↗

Stress in the human ankle joint: a brief review.

The articular bones of the ankle joint are subjected to stress along their vertical axis by the resultant force Rt [13]. On this compressive stress is superimposed bending resulting from tensile forces exerted by the collateral ligaments. The loading by tensile forces is greatest in the lateral areas of the joint, especially at the fibular malleolus. The bony elements of the ankle joint are adapted to this specific mode of stress by the distribution of osseous material in the subchondral bone and by cancellous architecture. Results from photoelastic model tests correspond to the morphological findings if models are subjected to stress by both compressive forces and tensile forces. Zones with high fringe orders of isochromatics in the model correspond to areas with high density of the osseous tissue in equidensity pictures, and the trajectorial pattern in Plexiglas models mirrors the alignment of compressive and tensile cancellous trabeculae.

Ankle Joint↗

[Stable ankle joint fractures. Indication for surgical or conservative management?].

In German literature, ankle joint fractures are mostly classified in three groups according to Weber. In cases of the type A, the fracture line runs below, in cases of type B at height of the syndesmotic ligaments. C-type fractures are typically seen above this region. However, this practical and simple classification allows no inferences at accompanying injuries which in turn influence the functional outcome. We observed isolated fractures of the lateral malleolus in more than 60% of all type B-fractures, as soon as in the majority the type A-fractures. Since isolated medial ankle fractures occur very rarely, careful exclusion of further injuries is advisable here. In order to differentiate stable ones from unstable type B ankle injuries, we carry out a manual stress test, if there is less than 2 mm fracture dislocation and a congruent ankle mortise. In this manner we could find that stable lateral ankle fractures are characterized with a combination of an intact dorsal syndesmotic and medial ligament. Stable type B and undisplaced type A fractures were treated conservatively with an ankle brace (Aircast?). Unstable ankle injuries were treated by ORIF. Conservative treatment for undisplaced medial malleolar fractures is recommended, if x-rays showed less than 2 mm dislocation which allows a tibio-talare impingement. Biomechanical investigations could prove a significant increase in ankle joint stability, when an axial load of 300 N was applied to various horizontal loads. The talus does not follow automatically a displaced fibular fracture. The dorsal syndesmotic and the medial deltoid ligaments control ankle joint stability.

Ankle Injuries↗

Biomechanics of the unstable ankle joint and clinical implications.

PURPOSE: The aim of this paper is to provide fundamental information about the biomechanics of the unstable ankle joint and to establish a rational for the daily clinic when dealing with patients in both, the acute and chronic unstable condition of the ankle joint complex. METHODS: The problem of the unstable ankle joint is worked up by analyses of the basic anatomy and biomechanics followed by an overview of its clinical manifestation including a differential diagnosis. RESULTS: The ankle joint and its surrounding ligaments represent a complex mechanical structure whose mechanical properties highly depend on ligament integrity. Recent in vitro studies have supported the hypothesis that, besides maintaining lateral ankle stability, the lateral ankle ligaments play a significant role in maintaining rotational ankle stability and in transferring movement between leg and foot. Instability of the ankle results from acute ligament injuries and may become chronic when complete ligament healing does not occur. Chronic instability syndrome may manifest with recurrent injuries with chronic lateral pain, tenderness, swelling, or induration with great difficulties in sports and daily activities. Symptomatic instability can be caused by mechanical instability with demonstrable instability, but it can be also present with no demonstrable instability. Impairment of ankle proprioception has been shown to be a major cause of symptomatic ankle instability. Other conditions may mimic ankle instability. CONCLUSIONS: The cause of chronic functional instability is often not mechanical instability but impairment of ankle proprioception. A history of insecurity, instability, and giving way is far more important in diagnosis than the physical and radiographic examination. If surgical treatment is advised, anatomical reconstruction of the ankle ligaments is mandatory for fear of altering the biomechanics.

Ankle Joint↗

[Indications, technique and results in treatment of the chronically unstable ankle joint].

This paper shall prove that with the chronic unstable ankle-joint the unit of both joints is to be taken into account. This unit consists anatomically as well as biomechanically and neuromuscularly. The practicable diagnostic of the instability in the lower ankle-joint ist presented. Then the known therapy methods are analysed. In our clinic some treatment methods for the single decompensate instabilities have proved success. The results of 119 operated decompensate ankle-joints are satisfied.

Adolescent↗

Relation between ankle joint dynamics and patellar tendinopathy in elite volleyball players.

OBJECTIVE: Ankle joint complex dynamics developed during volleyball spike jumps take-offs and landings were quantified to assess potential relations between these joint dynamics and patellar tendinopathy. DESIGN: Three-dimensional kinematic data provided information about movements of the lower limbs, while the kinetic data permitted analysis of ground reaction forces as players took-off and landed from full-speed spike jumps. SETTING: Simulated volleyball court with net in a biomechanics research laboratory. PARTICIPANTS: 10 members of the Canadian Men's National Volleyball Team. From history and physical examination, 3 of the 10 players had patellar tendon pain associated with activity and were diagnosed with patellar tendinopathy at the time of the study. Investigators were blinded about the injury status of the players. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Three-dimensional kinematics and joint moments of the ankle, knee, and hip joints. RESULTS: Our analysis revealed that maximal external tibial rotation occurred at or near maximal dorsiflexion while maximal internal tibial rotation coincided with maximal plantarflexion. The plantarflexion moment was 3 to 10 times greater than all the other moments measured, with the maximal plantarflexor moment being calculated at 0.4 BWm (360 Nm). In blinded logistic regression analyses, we found one of the dynamics variables (inversion moment during the landing of the spike jump) was a significant predictor of patellar tendinopathy. CONCLUSIONS: Coupling the results of the current analysis of ankle joint complex dynamics with previously reported results of knee joint dynamics related to patellar tendinopathy suggests that a cluster of variables linked to patellar tendinopathy includes: high ankle inversion-eversion moments, high external tibial rotation and plantarflexion moments, large vertical ground reaction forces, and high rate of knee extensor moment development.

Adult↗

Changes in ground reaction force during jump landing in subjects with functional instability of the ankle joint.

OBJECTIVE: To identify changes in ground reaction force during jump landing in subjects with functional instability of the ankle joint. DESIGN: Comparison of ground reaction force during jump landing between subjects with functional instability and healthy controls. BACKGROUND: We have recently demonstrated significantly altered patterns of ankle and knee movement immediately pre- and post-impact in subjects with functional instability compared to healthy controls. We now examine the changes in timing and magnitude of forces sustained by the unstable ankle during jump landing. METHODS: Fourteen subjects with unstable ankles and 10 age, sex and activity matched controls performed five single leg jumps onto a force platform whilst ground reaction forces were sampled. Timing and magnitudes of forces during the first 150 ms following impact were analysed and compared between groups. RESULTS: Lateral and anterior force peaks occurred significantly earlier in subjects with functional instability. Significant differences were seen between groups' time-averaged vertical, frontal and sagittal components of ground reaction force. These ranged from 5% (frontal force) to 100% (vertical force) of body mass. These changes occur immediately post-impact and too early for reflex correction/modification. CONCLUSIONS: The disordered force patterns observed in subjects with functional instability are likely to result in repeated injury due to significant increase in stress on ankle joint structures during jump landing. We suggest that they are most likely to result from deficits in feed-forward motor control. RELEVANCE: These results identify the potentially injurious nature of the changes in the forces applied to the unstable ankle joint during jump landing. The timing of these changes suggests that they are caused by a motor control deficit. Treatment approaches aimed at retraining feed-forward control of ankle joint movement could succeed in restoring more normal patterns of force absorption and reduce the occurrence of repeated micro-trauma to ankle structures.

Adaptation, Physiological↗

[Observation on therapeutic effect of acupuncture at Yanglingquan (GB 34) on sprain of external ankle joint].

OBJECTIVE: To observe the increasing effect of Yanglingquan (GB 34) on sprain of external ankle joint. METHODS: Seventy-nine cases of sprain of external ankle joint were semi-randomly divided into a treatment group (n = 46) and a control group (n = 33). The treatment group were treated with acupuncture at Yanglingquan (GB 34) and electro-magnetic therapy at local acupoints, and the control group with electro-magnetic therapy. RESULTS: The cured rate and the total effective rate were 67.4% and 91.3% in the treatment group, and 36.4% and 69.7% in the control group, respectively, with a significant difference between the two groups (P<0.01, P<0.05). CONCLUSION: Acupuncture at Yanglingquan (GB 34) has a better therapeutic effect on sprain of the external ankle joint.

Acupuncture Points↗

The effect of ankle joint position and effort on quadriceps reflex sensitivity.

OBJECTIVE: To investigate a possible ankle-knee synergy, experiments with normal subjects were performed to compare changes of the quadriceps motor pool excitability due to ankle position and effort. METHODS: Vastus medialis H reflex amplitude was examined during ankle isometric contractions conditioned by different ankle positions (dorsiflexion, neutral, and plantarfiexion) with or without voluntary effort (either in the dorsiflexion or plantarflexion direction). Repeated measures ANOVAs were performed on the mean and standard deviation of the H peak-to-peak amplitude. RESULTS: Mean vastus medialis H reflex amplitudes were significantly different among the trials of different ankle efforts (P<0.05), and significantly increased during plantarfiexion efforts. In contrast, mean vastus medialis H reflex amplitude did not vary with respect to changes of ankle position (P>0.05). CONCLUSIONS: The data suggest that (1) the position of the ankle joint did not significantly modify the excitability of the neuromotor pool of the VM muscle, in either static or active cases, and (2) the effort effect from the ankle joint on the VM neuromotor pool is most significant during ankle plantarfiexion effort. Possible mechanisms are central motor irradiation and peripheral force-dependent pathways from the ankle joint that influence the VM neuromotor pool.

Adult↗

Comparison of plain MRI and MR arthrography in the evaluation of lateral ligamentous injury of the ankle joint.

BACKGROUND: The purpose of this study was to determine the efficacy of plain magnetic resonance imaging (MRI) and magnetic resonance (MR) arthrography for detecting collateral ligamentous injury of the ankle joint. METHODS: Fifty patients (October 2001 to November 2003) suffering from ankle disability who underwent plain MRI and MR arthrographic studies were enrolled in this study. The diagnostic criteria for ligament disruption on plain MRI included nonvisualization, disruption, waviness of the ligament, or coexistent avulsion fracture. The MR arthrographic findings of ligament disruption were based on leakage of gadolinium contrast medium anterior to the anterior talofibular (ATaF) ligament following ATaF ligament disruption, and the contrast medium filling into the common peroneal tendon sheath after calcaneofibular (CF) ligament disruption. The 2 modalities were interpreted respectively and blindly. RESULTS: Seventeen patients received surgical intervention. There were 14 patients who had a torn ATaF ligament and 6 patients who suffered from CF ligament disruption proved by surgery. Limited detection of preoperative plain MRI survey, which showed 12 patients had torn ATaF and 2 patients had torn CF ligament, was noted. However, most patients with ligamentous injury were correctly diagnosed by MR arthrography preoperatively (only 1 case of CF injury was missed). The plain MRI alone had a higher incidence of false negative and false positive detection. MR arthrography was also valuable for evaluating the coexisting intra-articular pathologies of the ankle joint. CONCLUSION: For evaluating ankle disability, using plain MRI alone is not adequate for correctly detecting lateral collateral ligamentous injury of the ankle joint. MR arthrography improves the sensitivity and the accuracy for ATaF and CF ligament injuries. It also helps in assessing coexisting pathologic lesions of ankle joints, especially impingement syndromes and osteochondral lesions, and provides more information for therapeutic decision making.

Adolescent↗

Different frequency treadmill running in immobilization-induced muscle atrophy and ankle joint contracture of rats.

We investigated the effects of different frequencies of treadmill running on immobilization-induced soleus and gastrocnemius muscle atrophy and ankle joint contracture in rats using morphology and histochemistry. The right ankle joint of rat was immobilized for 2 weeks. Thereafter, the rats were randomly assigned to four groups for 6 weeks of exercise under different conditions: free cage activity and free remobilization (FR), once-a-week treadmill running (low-frequency running program (LFR)), three-time-a-week running (middle-frequency running program (MFR)), and six-time-a-week running (high-frequency running program (HFR)) groups. Two weeks of immobilization significantly reduced the cross-sectional area of soleus type I (62%, P<0.05) and type II muscle fibers (66%, P<0.05), gastrocnemius type I (78%, P<0.05) and type II muscle fibers (68%, P<0.05), and the range of ankle joint movement (46%, P<0.05). Immobilization also increased the ratio of type II to total fiber numbers in the soleus (P<0.05), and gastrocnemius (P<0.05), and induced pathological changes in muscle fibers. Some of these changes could not be corrected by free remobilization; however, the LFR, MFR, and HFR groups clearly recovered toward normal levels with exercise frequency, the effect on muscle recovery being more beneficial in the MFR and HFR groups. In addition, the range of ankle joint contracture was improved in LFR, MFR, and HFR groups in comparison with that in the FR group. These findings indicate that treadmill running exercise improved the immobilization-induced muscle fiber histochemical alterations and the range of the ankle motion in rats. Running three times and six times a week was more beneficial for recovery of immobilization-induced muscle atrophy and joint contracture compared with no running or once-a-week running.

Animals↗

Stabilometry recordings in functional and mechanical instability of the ankle joint.

Functional instability, i.e. recurrent sprains or a feeling of giving way in the joint, is common after ankle sprain. Using stabilometry, an objective and quantitative method for studying postural control, we earlier showed that soccer players with pathological stabilometric results are at risk for ankle joint injury. In the present study we found that the ability to maintain postural equilibrium as demonstrated by stabilometry was reduced among players with functional instability, but was not affected by mechanical instability. The results indicate that coordination and postural control are important for functional instability of the ankle.

Ankle Joint↗

Dependence of ankle joint width on plantar flexion.

Joint space narrowing is the first roentgenologic sign of osteoarthrosis of the ankle. In this report the dependence of ankle joint width on plantar flexion was investigated. In 30 adult volunteers without ankle symptoms, standardized anteroposterior views of the left ankle joint in neutral position and in 25 degrees plantar flexion were obtained. The average width of the joint space in neutral position was 2.7 mm in women, and 3.0 mm in men. A 25 per cent increment of the joint width following 25 degrees plantar flexion was observed. Accurate standardized positioning of the ankle appears to be decisive for the estimation of ankle joint width.

Adult↗

Effects of deep brain stimulation and medication on strength, bradykinesia, and electromyographic patterns of the ankle joint in Parkinson's disease.

We investigated the control of movement in 12 patients with Parkinson's disease (PD) after they received surgically implanted high-frequency stimulating electrodes in the subthalamic nucleus (STN). The experiment studied ankle strength, movement velocity, and the associated electromyographic patterns in PD patients, six of whom had tremor at the ankle. The patients were studied off treatment, ON STN deep brain stimulation (DBS), on medication, and on medication plus STN DBS. Twelve matched control subjects were also examined. Medication alone and STN DBS alone increased patients' ankle strength, ankle velocity, agonist muscle burst amplitude, and agonist burst duration, while reducing the number of agonist bursts during movement. These findings were similar for PD patients with and without tremor. The combination of medication plus STN DBS normalized maximal strength at the ankle joint, but ankle movement velocity and electromyographic patterns were not normalized. The findings are the first to demonstrate that STN DBS and medication increase strength and movement velocity at the ankle joint.

Ankle Joint↗