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Foot and ankle examination
Published in Maneesh Bhatia, Essentials of Foot and Ankle Surgery, 2021
Nikhil Nanavati, Nicholas Eastley, Maneesh Bhatia
Ask the patient to face a nearby wall and place both hands against it for support. Next, ask them to rise onto their tiptoes. In normal feet, the action of tibialis posterior on the naviculum will lead to varus tilt of the hindfoot (Figure 1.8). In cases of hindfoot stiffness, arthritis, coalition or tibialis posterior weakness, this will not occur and the hindfoot will remain in valgus. Note that in cases of severe ankle, subtalar or 1st MTPJ arthritis, patients may not be able to rise onto their tip toes due to pain. In cases of suspected pes planovalgus due to tibialis posterior insufficiency, ask the patient to perform repeated single heel raises. An inability to perform this ‘single stance’ test will highlight any subtle weakness in ankle plantar flexors (particularly tibialis posterior).
The Mechanics of Gait
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
With weight totally on the limb, stability is gained by extension of the knee and hip. During the early part of midstance the vector is still posterior to the knee and ankle. Therefore, dynamic mechanisms are needed. To allow knee extension, the rate of tibial advancement is slowed by action of the soleus muscle, assisted by the gastrocnemius. Quadriceps activity draws the femur forward. This action indirectly extends the hip, allowing the hip extensor muscles to relax. As the advancing vector becomes anterior to the knee, the quadriceps relaxes as well. Critical to this process is sufficient soleus muscle action to resist the anteriorly aligned vector that is inducing passive dorsiflexion. A contracture of the plantar flexors, which stabilizes the ankle at neutral, is a useful substitute.
Substantive Issues in Running
Published in Christopher L. Vaughan, Biomechanics of Sport, 2020
Carol A. Putnam, John W. Kozey
The RJM at the ankle is insignificant during the swing phase.79 A very brief phase of dorsiflexor ankle moment during the initial post-contact phase helps to pull the tibia forward following foot strike.94 The plantar flexors dominate for the remainder of the stance phase. This moment is initially eccentric and helps to absorb the shock of landing and control the forward rotation of the tibia over the ankle, and is later concentric as it aids in propulsion.78,94 The decrease in magnitude of this propulsive moment as toe-off is approached, may be due to the rapid rate of shortening of the plantar flexors.79 The propulsive role of the plantar flexors is considered to be very important in running.79 Ae et al.87 found that the positive work done by the plantar flexors was highly correlated with stride length and stride frequency.
Rehabilitation of Postural Control and Gait in Children with Cerebral Palsy: the Beneficial Effects of Trunk-Focused Postural Activities
Published in Developmental Neurorehabilitation, 2023
Jonathan Pierret, Christian Beyaert, Rajul Vasa, Emilie Rumilly, Jean Paysant, Sébastien Caudron
In our analysis of the WA phase of gait in children with CP, we observed moderate-to-strong correlations between the peak negative ankle power, on one hand, and the peak sternum anterior deceleration at M0, M3, and M6 and peak sacrum downward deceleration at M0 and M3 on the other. This correlation is in line with the early action exerted by the plantar flexors, since the angular deceleration of the trunk in the sagittal plane is strongly and primarily influenced by the plantar flexion moment generated at the ankle at the beginning of the stance phase.91 In toe-walking, the plantar flexors exert a decelerating action on ankle dorsiflexion, the associated anterior tilt of the tibia,92 and the downward and forward displacements of the CoM and the trunk from IC onwards.58,60
Cut-off score of the modified Ashworth scale corresponding to walking ability and functional mobility in individuals with chronic stroke
Published in Disability and Rehabilitation, 2023
Bruno Freire, Marja Bochehin do Valle, Fabio Juner Lanferdini, Clarissa Volpato Sombrio Foschi, Libak Abou, Caroline Pietta-Dias
According to the cut off score, a marked or considerable increased muscle tone in plantar flexors (MAS >2) corresponds to poor performance on TUG test. The low sensitivity values did not allow to identify individuals with low performance; however, the highest specificity allows to predict good mobility performance in individuals after stroke. Thus, reducing spasticity in the plantar flexors might induce an improvement in mobility. For example, one month after injecting botulinum toxin in individuals with chronic spasticity (35/39 caused by stroke), a previous study reported a significant statistical change on the TUG test (baseline = 23.03 s; follow up = 20.93 s; p = 0.01) [18]. Despite the change found was inferior to the minimal detectable change (MDC = 2.9 s) highlighted by Flansbjer et al. [19], participants achieved TUG test values close to the MDC even without performing specific exercises for mobility [20]. The finding on the low sensitivity of the TUG seems to show that test performance might be related to a smaller influence of the calf muscle group on the sit to stand task combined to walking when compared to walking alone (this behavior also justifies the finding observed for the FTSTS). Therefore, when clinicians identify limited TUG performance and mobility tasks, they should investigate factors beyond plantar flexor spasticity specifically, because that might not be the actual rehabilitation target.
Using Corticomuscular and Intermuscular Coherence to Assess Cortical Contribution to Ankle Plantar Flexor Activity During Gait
Published in Journal of Motor Behavior, 2019
Peter Jensen, Rasmus Frisk, Meaghan Elizabeth Spedden, Svend Sparre Geertsen, Laurent J. Bouyer, David M. Halliday, Jens Bo Nielsen
Ankle plantar flexor muscles are of fundamental importance for human gait since they exert their action directly on the supporting ground and are in a position to both support the body against gravity and help to propel the body forward by providing a forward thrust at push-off (Winter, 1983). Despite a long-standing debate there is no general consensus as to whether their main role is in support or forward propulsion (Honeine, Schieppati, Gagey, & Do, 2013; Neptune et al., 2001). According to the controlled roll-off theory the plantar flexors mainly contribute to ensure stability, while the body rotates over the stance leg (Honeine et al., 2013), whereas the push-off theory suggests that the plantar flexors actively push the body forward late in stance (Neptune & Kautz, 2001; Winter, 1983). It has also been suggested that the primary role of the plantar flexors would be to propel the limb into flexion and that the main forward propulsion is generated later as energy from the swing leg is transferred to the trunk (Hof, Nauta, van der Knaap, Schallig, & Struwe, 1992; Meinders, Gitter, & Czerniecki, 1998). Unfortunately, there are still several limitations to current forward kinematics modeling and inverse dynamics calculations obtained from biomechanical gait analysis that limit our ability to address the details of this question at the moment.