Ankle Loading Research Articles

Effect of Increased Weight on Ankle Mechanics and Spatial Temporal Gait Mechanics in Healthy Controls

Ankle osteoarthritis has been associated with trauma, instability, and inflammatory arthritis. Limited literature exists examining the effect of body weight on ankle joint loading. The purpose of this study was to examine the relationship between increased weight and gender on ankle kinematics and kinetics. Fifty-three (28 male, 25 female) subjects were recruited for the study. All subjects underwent a standard level walking gait analysis in four different weight conditions (normal, 10%, 15%, and 20% increased body weight). Testing order was randomized. A series of mixed-factor, repeated-measures analyses of variance (weight by gender) were used to determine statistical differences between the groups (p < .05). Walking speed was not significantly different between gender or weight conditions. No significant differences existed for step length, step time, stride length, swing time, or sagittal plane ankle kinematics and kinetics. A significant increase in plantarflexion moment existed for the males (p < .05). The peak plantarflexion moment increased as weight increased. Single support time (p = .042) was significantly different between the no weight and the 15% and 20% increased weight conditions. In addition, double support time was significantly longer in the males compared with females (p < .001) and significantly increased for each weight condition (p < .001). Increasing weight alters spatial temporal mechanics and sagittal plane ankle kinetics in a healthy control population. The effect of increasing weight appears to be similar between genders. The findings of the present study may be relevant for future studies to assess the role of weight as a potential covariate on postoperative outcomes and gait mechanics.

Comparative Three‐Dimensional Structure of the Trabecular Bone in the Talus of Primates and Its Relationship to Ankle Joint Loads Generated During Locomotion

The trabecular structure of the ankle bone in small to medium-bodied (60-5000 g) primates of distinct locomotor types was analyzed using high-resolution X-ray computed tomography. There are large inter-, intraspecific, and regional (medial vs. lateral) variations in the trabecular architecture of the talar body. Body mass has no effect on the bone volume fraction or on the fabric anisotropy. However, both the number and thickness of trabeculae seem to be body mass-dependent. All taxa show anisotropic trabecular bone, but the degree of anisotropy and elongation values vary, notably across the locomotion categories. The fabric orientation in the talar body indicates that, practically, all taxa studied display a generally consistent pattern of orientation restricted primarily to a dorsoplantar direction. We have observed a mediolateral difference in the bone volume fraction in most primates who are proficient or frequent climbers. This could reflect a specific reinforcement of the trabecular structure in response to the loads engendered in habitually sustained foot inversion. In contrast, tali of primates who are proficient or frequent leapers rather exhibit a different three-dimensional distribution of the material, which consists of a more anisotropic trabecular structure. This could reflect stronger unidirectional and stereotypical-loading conditions generated at the ankle joints during a leap. Finally, it appears that the talar trabecular bone structure has a good potential for predicting locomotion in extinct species. We have analyzed the trabecular bone structure of the talus of some Eocene European primates (Adapis, Leptadapis, and Necrolemur) and compared the functional signal of the external versus internal talar anatomy in these fossils.

Force and Displacement Measurements of the Distal Fibula during Simulated Ankle Loading Tests for High Ankle Sprains

Syndesmosis (high ankle) sprains produce disruption of the distal tibiofibular ligaments. Forces on the distal fibula that produce these injuries are unknown. Twenty-seven fresh-frozen lower extremities were used for this study. A load cell recorded forces acting on the distal fibula from forced ankle dorsiflexion and applied external foot torque; medial-lateral and anterior-posterior displacements of the distal fibula were recorded. Fibular forces and axial displacements were also recorded with applied axial force. During forced ankle dorsiflexion and external foot torque tests, the distal fibula always displaced posteriorly with respect to the tibia with no measurable medial-lateral displacement. With 10 Nm dorsiflexion moment, cutting the tibiofibular ligaments approximately doubled fibular force and displacement values. Cutting the tibiofibular ligaments significantly increased fibular displacement from applied external foot torque. Fibular forces and axial displacements from applied axial weight-bearing force were highest with the foot dorsiflexed. The highest mean fibular force in the study (271.9 N) occurred with 10 Nm external foot torque applied to a dorsiflexed foot under 1000 N axial force. Two important modes of loading that could produce high ankle sprains were identified: forced ankle dorsiflexion and external foot torque applied to a dorsiflexed ankle loaded with axial force. The distal tibiofibular ligaments restrained fibular displacement during these tests. Residual mortise widening observed at surgery may be the result of tibiofibular ligament injuries caused by posterior displacement of the fibula. Therefore, a syndesmosis screw used to fix the fibula would be subjected to posterior bending forces from these loading modes. Ankle bracing to prevent extreme ankle dorsiflexion during rehabilitation may be advisable to prevent excessive fibular motions that could affect syndesmosis healing.

The effect of external ankle support on knee and ankle joint loading in netball players

Background External ankle support has been successfully used to prevent ankle sprains [1]. However, some recent studies [2,3] have indicated that reducing ankle range of motion can place larger loads on the knee and increase the risk of knee injuries. The aim of this study is to investigate the effect of external ankle support (braces and high top shoes) on ankle kinematics and knee kinetics in high performance netball players. Materials and methods Eleven high performance netball players were recruited from NSW Institute of Sport. A 14-camera motion analysis system was used to synchronously collect threedimensional video and force plate data. Twenty-four retro-reflective markers were attached to anatomical landmarks to allow the formation of rearfoot, forefoot, shank, thigh, and pelvis segments. Each player performed a single-leg-landing whilst receiving a chest pass.

Task-specific initial impact phase adjustments in lateral jumps and lateral landings

Load-dependant adjustments in lateral jumps are thought to rely on foot placement and on upper leg's kinematic and neuromuscular adaptations. The aim of this study was to elucidate task-specific adjustments during the initial impact phase under varying stretch-loads by the comparison of lateral jumps and lateral landings. Ten subjects performed lateral jumps and landings from four distances. Electromyographic (EMG) data of five lower extremity muscles were measured, whilst lower extremity kinematics and kinetics were analysed by 3D motion analysis. Lateral jumps were characterized by increased impact forces, higher lower extremity joint moments with exception of the initial knee abduction moment, greater sagittal knee and hip joint displacements, and a further exorotated foot placement. In lateral landings frontal ankle and hip joint displacements were greater. Thigh muscle and m. tibialis anterior (TA) pre-activity as well as initial post-impact EMG were higher in lateral jumps than in lateral landings, whilst during the reflex-induced phase thigh and shank muscle EMG, except for TA, were enhanced in lateral jumps. From these findings it can be concluded that task specificity in lateral jumps in contrast to lateral landings impedes a stretch-load adequate modulation of initial impact forces which particularly affects ankle joint loading. Foot placement seems to play a decisive role for limiting lateral ankle and medial knee joint loading. Therefore, in sports containing high-impact frontal plane movements a special emphasis in training routines should be paid to foot placement strategy in those movements. Such training interventions might contribute to injury prevention in lateral movements.

Explanatory Variables for Adult Patients' Self-Reported Recovery After Acute Lateral Ankle Sprain

Longitudinal research on musculoskeletal disorders often makes use of a single measure of recovery, despite the large variation in reported recovery that exists. Patients with an acute ankle sprain often experience no pain or functional disability following treatment, yet report not being fully recovered, or vice versa. The purpose of this study was to find explanatory variables for reporting recovery by analyzing the extent to which different outcomes (eg, pain intensity) were associated with recovery and how baseline scores of different variables influence this association in adult patients after acute lateral ankle sprain. This was a cohort study based on data collected in a randomized controlled trial (RCT). This study was constructed within the framework of an RCT. One hundred two patients who incurred an acute ankle sprain were included. Recovery, pain intensity, giving way of the ankle, and Ankle Function Score (AFS) were assessed during the RCT at baseline and at 4 weeks, 8 weeks, 3 months, and 12 months postinjury. Mean differences were calculated between baseline and follow-up. Associations were calculated using linear mixed models, and the influence of baseline scores on these associations was determined using linear regression with interaction. Associations were found between recovery and the mean differences of pain during running on flat and rough surfaces (4 and 8 weeks, 3 months) and between recovery and the mean difference of giving way of the ankle during walking on a rough surface (8 weeks, 3 months). This study used data collected from an RCT. Therefore, the study was limited to the outcomes measured in that trial, and some explanatory factors easily could have been missed. This study is the first to identify explanatory variables for reporting recovery in adults after ankle sprain. Pain intensity and giving way of the ankle measured during high ankle load activities make it easier to measure and to generalize recovery in this population and should be the primary outcome measures of interest. This study indicates the huge need to reach consensus about primary outcome measures for research in patients sustaining ankle sprains.

Effect of Ankle Taping on Knee and Ankle Joint Biomechanics in Sporting Tasks

Prophylactic taping is commonly used to prevent ankle injuries during sports. However, unnatural constraint of the ankle joint may increase the risk of injury to proximal joints such as the knee. The association between ankle taping and knee joint loading during open sporting tasks has not been quantified. This research aimed to measure changes in knee and ankle kinetics and kinematics during dynamic athletic activities undertaken with and without ankle taping. A kinematic and inverse dynamics model was used to determine ankle and knee joint motion and loading in 22 healthy male participants undertaking running and sidestepping tasks. Both tasks were randomized to planned and unplanned conditions and undertaken with and without the use of ankle tape. At the knee, peak internal rotation moments (P < 0.001) and peak varus moments (P < 0.05) were significantly reduced during all running and sidestepping trials (planned and unplanned) when undertaken with ankle tape. Internal rotation impulse (P < 0.001) was reduced for sidestepping tasks. Varus impulse during unplanned sidestepping maneuvers (P = 0.04) was reduced with the use of ankle tape. However, there was a trend toward increased valgus moments and impulse for planned sidestepping trials undertaken with ankle tape(P = 0.056). Taping reduced the range of motion at the ankle in all three planes (P < 0.05). Peak inversion (P < 0.001) was reduced for running trials only. Average eversion and peak dorsiflexion moments were significantly reduced in sidestepping tasks by use of taping. By limiting motion at the ankle, taping increased mechanical stability at this joint. Ankle taping also provided protective benefits to the knee via reduced internal rotation moments and varus impulses during both planned and unplanned maneuvers. Medial collateral and anterior cruciate ligament injuries may, however, occur through increased valgus impulse during sidestepping undertaken with ankle tape.

Lower extremity joint loading during level walking with Masai barefoot technology shoes in overweight males

The purpose of this study was to evaluate the effects of Masai barefoot technology (MBT) shoes on lower extremity joint loading in overweight males during level walking. Therefore, lower extremity kinematics, kinetics, and muscle electromyographic signals of the vastus lateralis (VL), biceps femoris (BF), and gastrocnemius medialis (GM) were recorded in 10 overweight males at a self-chosen walking speed with MBT shoes and conventional shoes. Selected peak joint moments, maximal joint force loading rates, mean muscle intensities, and co-activation indices of the VL/BF, as well as of the VL/GM were analyzed and compared for the two shoe conditions using paired Student's t-tests (α=0.05). Results showed that walking with MBT shoes reduced first peak knee adduction moments in overweight subjects. During midstance and terminal stance, increases in VL/GM co-activation, accompanied by increases in VL and GM (only terminal stance) intensities were found for the MBT situation. Kinetic variables analyzed to assess ankle and hip joint loading did not exhibit any statistical differences. These results suggest that using MBT shoes diminishes medial compartment loads at the knee without overloading hip or ankle joints in overweight males. However, the additional muscle loading should not be overlooked, and warrants further investigation.

Leg Asymmetries and Coordination Dynamics in Walking

ABSTRACT Models of interlimb coordination (H. Haken, J. A. S. Kelso, & H. Bunz, 1985; P. N. Kugler & M. T. Turvey, 1987) were tested in walking by examining the role of asymmetries between limbs. Participants walked on a treadmill with and without a metronome. Five asymmetry conditions were created via ankle loads of 0, 3, or 6 kg on either leg. With the metronome, participants matched the target period. Without the metronome, stride rate slowed as the mass was increased on either leg. The loads led to an increase in stride period that was predicted by Huygens’ law and the hybrid pendulum-spring model. In agreement with extended Haken–Kelso–Bunz model predictions, leg asymmetries led to deviations from antiphase coordination. Also, perception–action coordination was influenced by the asymmetry between the legs and metronome. In contrast, no predicted stability effects were observed. These findings reveal that some properties of interlimb coordination, apparent in laboratory-based tasks, can also be observed in human walking.

The influence of soccer cleat design on resultant joint moments

Footwear traction has previously been associated with lower extremity injury such as ankle and knee sprains. Recent changes in soccer shoe cleat design such as the introduction of bladed cleats have the potential to dramatically affect footwear traction. Therefore, the purpose of this study was to determine how soccer cleats of different designs and traction influence resultant ankle and knee joint moments during soccer movements. Two traditional soccer cleat designs and one bladed cleat design were compared to a standard running shoe as the control condition. Translational and rotational traction of the shoes on artificial turf were measured using a Stewart platform. Ankle and knee joint moments were quantified on a group of 12 recreational soccer players while performing cutting and turning movements at 4.0 m s−1 on the same artificial turf. All soccer shoes had significantly higher rotational traction than the running shoe but there were no significant differences between cleat designs. The bladed cleat design had significantly higher translational traction than the traditional cleat designs. As a result, the bladed cleat design that was tested appears effective at decoupling translational and rotational traction characteristics of soccer shoes, which could potentially be beneficial in reducing injuries. There were no significant differences in resultant ankle and knee joint moments between the shoes during the cutting movement. During the turning movement, the cleated shoes had significantly higher ankle and knee rotation moments than the control running shoe. Thus, increased rotational traction increases ankle and knee joint loading which in turn could lead to a greater incidence of injury, however, it is important to note that this was only true during a rotational movement.

How Isometric Are the Medial Patellofemoral, Superficial Medial Collateral, and Lateral Collateral Ligaments of the Knee?

Background Ligament isometry is a cornerstone in the description of normal knee function and thorough knowledge is mandatory for successful repair of torn ligaments. Purpose This study was undertaken to validate a novel experimental model for the study of ligament strains and to determine the length changes in the superficial medial collateral, lateral collateral, and medial patellofemoral ligaments. Study Design Descriptive laboratory study. Methods Passive motions and loaded squats of 12 cadaveric specimens were performed while controlling ankle load and optically tracking the motion of the bones. Preexperiment and postexperiment computed axial tomography scans allow the transformation of rigid body motion to relative motion of relevant anatomic landmarks on the femur, tibia, and patella. Results The superficial medial collateral ligament is a near-isometric ligament with a strain of less than 2%. The ligament is a little more slack in midflexion (30° to 50°) and in deep flexion, but length changes are not significant (P > .05). The lateral collateral ligament behaves near isometric (<2% strain) from 0° to 70° of knee flexion. Cartilage compression in a loaded environment relieves tension from the collateral ligaments (P < .05). The medial patellofemoral ligament is nonisometric. The cranial part of the medial patellofemoral ligament is most taut at full extension, while the caudal part is most taut at 30° of knee flexion. Conclusion Ligament insertion sites on the femur, patella, and fibula can be derived from computed axial tomography scans. The described model allows the study of dynamic ligament behavior. The superficial medial collateral ligament is a near-isometric ligament with no significant length changes. The medial patellofemoral ligament behaves differently in its cranial and caudal parts. Clinical Relevance In knees with chronic medial collateral ligament insufficiency, isometric repair of the superficial medial collateral ligament can be attempted. A medial patellofemoral ligament reconstruction with a double fixation on the medial patellar border is supported. The cranial bundle should be tightened at full extension and the caudal bundle at 30° of knee flexion.

Early independent walking: A longitudinal study of load perturbation effects

This study investigated infants' ability to adapt to experimentally induced changes in their body dimensions at walk onset, and how this ability is affected by increased walking experience. Fifteen infants were studied over their first 6 months of independent walking with a load perturbation design. They traversed a walkway with loads symmetrically placed around the shoulders, waist, or ankles, and without loading. At walk onset, infants fell more with shoulder and ankle loads than with waist or no loads. Shoulder loads further resulted in higher walking speed and longer steps, while waist loads resulted in increased walking speed and larger foot rotation. Ankle loads disrupted walking proficiency the most, as indicated by lower walking speed, shorter steps, larger foot rotation, and smaller step-to-step angle. Step width was not differentially affected by the conditions. With increased experience, walking proficiency increased across all conditions, but ankle loads lagged behind the other conditions. Loading effects are discussed with respect to walking experience and position of the loads on the body.

Ankle Load Modulates Hip Kinetics and EMG During Human Locomotion

The purpose of this research was to examine the role of isolated ankle-foot load in regulating locomotor patterns in humans with and without spinal cord injury (SCI). We used a powered ankle-foot orthosis to unilaterally load the ankle and foot during robotically assisted airstepping. The load perturbation consisted of an applied dorsiflexion torque designed to stimulate physiological load sensors originating from the ankle plantar flexor muscles and pressure receptors on the sole of the foot. We hypothesized that 1) the response to load would be phase specific with enhanced ipsilateral extensor muscle activity and joint torque occurring when unilateral ankle-foot load was provided during the stance phase of walking and 2) that the phasing of subject produced hip moments would be modulated by varying the timing of the applied ankle-foot load within the gait cycle. As expected, both SCI and nondisabled subjects demonstrated a significant increase (P < 0.05) in peak hip extension moments (142 and 43% increase, respectively) when given ankle-foot load during the stance phase compared with no ankle-foot load. In SCI subjects, this enhanced hip extension response was accompanied by significant increases (P < 0.05) in stance phase gluteus maximus activity (27% increase). In addition, when ankle-foot load was applied either 200 ms earlier or later within the gait cycle, SCI subjects demonstrated significant phase shifts ( approximately 100 ms) in hip moment profile (P < 0.05; i.e., the onset of hip extension moments occurred earlier when ankle-foot load was applied earlier). This study provides new insights into how individuals with spinal cord injury use sensory feedback from ankle-foot load afferents to regulate hip joint moments and muscle activity during gait.

Prediction of Three-Dimensional Contact Stress and Ligament Tension in the Ankle During Stance Determined from Computational Modeling

Our goal was to quantify and visualize the three-dimensional loading relationship between the ligaments and articular surfaces of the ankle to identify and determine the stabilizing roles of these anatomical structures during the stance phase of gait. We applied discrete element analysis to computationally model the three-dimensional contact characteristics and ligament loading of the ankle joint. Physiologic loads approximating those at five positions in the stance phase of a normal walk cycle were applied. We analyzed joint contact pressures and periankle ligament tension concurrently. Most ankle joint loading during the stance phase occurred across the articular surfaces of the joint, and the amount of ligament tension was small. The tibiotalar articulation showed full congruency throughout most of the stance phase, with peak pressure developing anteriorly toward the toe-off frame. Of the periankle ligaments, the deep deltoid ligament transferred the most force during the stance phase (57.2%); the superficial deltoid ligament transferred the second-most force (26.1%). The anterior talofibular ligament transferred force between the talus and fibula continuously, whereas the calcaneofibular ligament did not carry force during gait. The distal tibiofibular ligaments and the interosseous membrane were loaded throughout the stance phase. Force transmission through the ankle joint during the stance phase is predominantly through the articular surfaces, and the periankle ligaments do not play a major stabilizing role in constraining ankle motion. The medial ligaments have a more important role than do the lateral ligaments in stabilizing the ankle joint. In addition to ligament insufficiency, other factors, such as varus tilt of the tibial plafond, may be important in the development of recurrent instability. Continuous loading of syndesmosis ligaments provides a theoretical basis for evidence of syndesmosis screw breakage or loosening. The analysis method has potential applications for clarifying ankle joint function and providing a basis for comparison between normal and abnormal joint conditions.

Joint loading-driven bone formation and signaling pathways predicted from genome-wide expression profiles

Joint loading is a recently developed loading modality that induces anabolic responses by lateral loads applied to a synovial joint such as an elbow and a knee. The present study extended this loading modality to an ankle and addressed a question: does ankle loading promote bone formation in the tibia? If so, what signaling pathways are involved in the anabolic responses? Using C57BL/6 female mice as a model system, lateral loads of 0.5 N were applied to the ankle at 5 Hz for 3 min/day for 3 consecutive days and load-driven bone formation was evaluated at three tibial cross-sections (the proximal, middle, and distal diaphysis). Furthermore, total RNA was isolated for 3 pairs of microarray experiments as well as quantitative real-time PCR analyses. The histomorphometric results revealed that in all cross-sections ankle loading elevated the cortical area and thickness as well as the calcein-labeled surface. Signaling pathway analysis from microarray-derived whole-genome mRNA expression profiles and quantitative real-time PCR predicted that molecules in phosphoinositide 3-kinase (PI3K), ECM-receptor interactions, TGFβ signaling, and Wnt signaling were involved in the joint-loading driven responses. Since ankle loading stimulates bone formation throughout the tibia both in the endosteum and the periosteum, it may provide a non-pharmacological approach to effectively activate molecular signaling necessary for preventing bone loss.

The influence of muscle load on tibiofemoral knee kinematics

A comparative kinematics study was conducted on six cadaver limbs, comparing tibiofemoral kinematics in five conditions: unloaded, under a constant 130 N ankle load with a variable quadriceps load, with and without a simultaneous constant 50 N medial and lateral hamstrings load. Kinematics were described as translation of the projected centers of the medial (MFT) and lateral femoral condyles (LFT) in the horizontal plane of the tibia, and tibial axial rotation (TR) as a function of flexion angle. In passive conditions, the tibia rotated internally with increasing flexion to an average of -16 degrees (range: -12/-20 degrees , SD = 3.0 degrees ). Between 0 and 40 degrees flexion, the medial condyle translated forwards 4 mm (range: 0.8/5.5 mm, SD = 2.5 mm), followed by a gradual posterior translation, totaling -9 mm (range: -5.8/-18.5 mm, SD = 4.9 mm) between 40-140 degrees flexion. The lateral femoral condyle translated posteriorly with increasing flexion completing -25 mm (range: -22.6 to -28.2 mm, SD = 2.5 mm). Dynamic, loaded measurements simulating a deep knee bend were carried out in a knee rig. Under a fixed ankle load of 130 N and variable quadriceps loading, tibial rotation was inverted, mean TR = 4.7 degrees (range: -3.3 degrees /11.8 degrees SD = 5.4 degrees ), MFT = -0.5 mm (range: = -4.3/2.4 mm, SD = 2.4 mm), LFT = 3.3 mm (range: = -3.6/10.6 mm, SD = 5.1 mm). Compared to the passive condition, all these excursions were significantly different (p < or = 0.015). Adding medial and lateral hamstrings force of 50 N each reduced TR, MFT, and LFT significantly compared to the passive condition. In general, loading the knee with hamstrings and quadriceps reduces rotation and translation compared to the passive condition. Lateral hamstring action is more influential on knee kinematics than medial hamstrings action.

Intralimb compensation strategy depends on the nature of joint perturbation in human hopping

Due to the well-described spring-mass dynamics of bouncing gaits, human hopping is a tractable model for elucidating basic neuromuscular compensation principles. We tested whether subjects would employ a multi-joint or single-joint response to stabilize leg stiffness while wearing a spring-loaded ankle-foot orthosis (AFO) that applied localized resistive and assistive torques to the ankle. We analyzed kinematics and kinetics data from nine subjects hopping in place on one leg, at three frequencies (2.2, 2.4, and 2.8 Hz) and three orthosis conditions (freely articulating AFO, AFO with plantarflexion resistance, and AFO with plantarflexion assistance). Leg stiffness was invariant across AFO conditions, however, compensation strategy depended upon the nature of the applied load. Biological ankle stiffness increased in response to a resistive load at twice the rate that it decreased with an assitive load. Ankle adjustments alone fully compensated for an assistive load with no net change in combined (biological plus applied) total ankle stiffness ( p⩾0.133). In contrast, a resistive load resulted in a 7.4–9.0% increase in total ankle stiffness across frequencies and a concomitant 10–15% increase in knee joint stiffness at each frequency ( p⩽0.037). The increased knee joint stiffness in response to resistive ankle load allowed subjects to maintain a more flexed knee at mid-stance, which attenuated the effect of the increased total ankle joint stiffness to preserve leg stiffness and whole limb biomechanical performance. Our findings suggest humans maintain invariant leg stiffness in bouncing gaits through different intralimb compensation strategies that are specific to the nature of the joint loading.

Spastic Reflexes Triggered by Ankle Load Release in Human Spinal Cord Injury

The rapid decrease in firing of load-sensitive group Ib muscle afferents during unloading may be particularly important in triggering the swing phase of gait. However, it still remains unclear whether load-sensitive muscle afferents modulate reflex activity in human spinal cord injury (SCI), as suggested by studies in the cat. The right hip of 12 individuals with chronic SCI was subjected to ramp (60 degrees /s) and hold (10 s) movements over a range from 40 degrees flexion to 0-10 degrees extension using a custom servomotor system. An ankle dorsiflexion load was imposed and released after the hip reached a targeted position using a custom-designed pneumatic motor system. Isometric joint torques of the hip and knee, reaction torque of the ankle, and surface electromyograms (EMGs) from eight muscles of the leg were recorded following the imposed hip movement and ankle load release. Reflexes, characterized by hip flexion torque, knee extension, and coactivation of ankle flexors and extensors, were triggered by ankle load release when the hip was in an extended position. The ankle load release was observed to enhance the reflexes triggered by hip extension itself, suggesting that ankle load afferents play an important role in spastic reflexes in human SCI and that the reflex pathways associated with ankle load afferents have important implications in the spinal reflex regulation of human movement. Such muscle behaviors emphasize the role of ankle load afferents and hip proprioceptors on locomotion. This knowledge may be especially helpful in the treatment of spasms and in identifying rehabilitation strategies for producing functional movements in human SCI.

Ground reaction force in basketball cutting maneuvers with and without ankle bracing and taping

In basketball, the most common injuries are ankle sprains. For this reason, players frequently use external ankle devices or taping as prophylactic and rehabilitation measures. The purpose of this study was to evaluate ground reaction force (GRF) responses in basketball players while performing typical cutting maneuvers with and without ankle bracing and ankle taping. Comparative study with experimental design of single-group repeated measurements, at Medical Rehabilitation Division, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo. Vertical (Fy) and medial-lateral (Fz) GRF measurements were made under three conditions (taping, Aircast-type orthosis and basketball shoes alone), with analysis of peak forces at foot contact (Fymax1, Fzmax1, Fymax2 and Fzmax2), growth gradient (peak/time) (GG Fymax1, GG Fzmax1, GG Fymax2 and GG Fzmax2) and impulse after foot contact. Bracing significantly reduced Fymax2 and GG Fymax2. GG Fzmax1 was significantly higher for the sport shoe condition than for the taping condition. Taping increased Fy in relation to the sport shoe at foot contact, but over a longer time interval, without increasing excessive ankle loading. Fz reached a peak in less time, which might generate greater inversion/eversion loading on a player's foot. The Aircast exerted better shock-absorbing effect than did the other two conditions, since it generated less vertical force over longer time intervals and smaller medial-lateral forces in relation to taping. Ankle bracing and ankle taping action mechanisms are still unclear and therefore should be carefully prescribed. More studies are needed to clarify taping and bracing effects on sporting activities.

Extensor Retinaculum Augmentation Reinforces Anterior Talofibular Ligament Repair

Repair of the anterior talofibular ligament often is augmented with the inferior extensor retinaculum because it is thought to reinforce the primary ligament repair. The additional dissection and suturing extend the duration of surgery, and not all surgeons routinely include inferior extensor retinaculum augmentation in anterior talofibular ligament repairs. To determine whether there is a reasonable basis for this surgery, we ascertained the degree to which inferior extensor retinaculum augmentation reinforced the primary anterior talofibular ligament repair. Matched pairs of cadaveric ankles had controlled inversion while monitoring resistance to inversion, first with the anterior talofibular ligament sectioned, then with primary anterior talofibular ligament repair alone or with inferior extensor retinaculum augmentation. The resistance to ankle inversion was greater at 5 degrees, 10 degrees, 15 degrees, 20 degrees, and 25 degrees rotation in ankles that had inferior extensor retinaculum augmentation. Anterior talofibular ligament failure occurred at similar inversion angles in both treatment groups, but the primary anterior talofibular ligament repair required more torque to fail in the augmented group. With these ankle loading conditions, inferior extensor retinaculum augmentation provided protection to the primary anterior talofibular ligament repair, indicating that broader clinical use of augmentation may be warranted.