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Biomechanics and Joint Replacement of the Foot and Ankle
Published in Manoj Ramachandran, Tom Nunn, Basic Orthopaedic Sciences, 2018
Rohit Madhav, Amit Amin, Deborah Eastwood, Dishan Singh
The subtalar joint also demonstrates linear motion, i.e. anteroposterior movement. This is likened to the Archimedes spiral screw (mean helix angle 12°), where rotational movements are converted to linear motion. The calcaneum moves forwards in inversion and backwards in eversion. For practical purposes, foot motion can be considered to be of two distinct types – non-weight bearing and weight bearing. Active weight-bearing motion of the foot differs from passive motion because of forces produced by the body weight and by muscle contractions that act to stabilize the joints. When an individual stands on the ball of the foot, the hindfoot inverts slightly and the midfoot is in plantarflexion and the forefoot exhibits some pronation, creating an arch. Standing flatfooted on an externally rotating leg also raises the arch by moving the heel into slight inversion and causing the forefoot to twist into pronation. Rotating the leg internally has the opposite effect: it lowers the arch.
Paper 7 Questions
Published in Hayley Dawson, Anna Trigell, EMQs for the nMRCGP® Applied Knowledge Test, 2018
A 45-year-old woman complains of a sharp pain in the ball of her foot radiating into her toes when she goes out of the house. The pain is relieved when she removes her footwear and massages the foot. Examination reveals decreased sensation in the area that is causing the pain.
The ankle and foot
Published in Ashley W. Blom, David Warwick, Michael R. Whitehouse, Apley and Solomon’s System of Orthopaedics and Trauma, 2017
Morton’s metatarsalgia is a common problem, with neuralgia affecting a single distal metatarsal interspace, usually the third (affecting the third and fourth toes), sometimes the second (affecting the second and third toes), rarely others. The patient typically complains of pain on walking, with the sensation of walking on a pebble in the shoe, or of the sock being rucked-up under the ball of the foot. The pain is worse in tight footwear and often has to be relieved by removing the footwear and massaging the foot. Activities that load the forefoot (running, jumping, dancing) exacerbate the condition, which often consists of severe forefoot pain and then a reluctance to weight-bear. In Morton’s metatarsalgia the pain is typically reproduced by laterally compressing the forefoot while also compressing the affected interspace – this produces the pathognomic Mulder’s click as the ‘neuroma’ displaces between the metatarsal heads.
The dysmorphic metatarsal parabola in diabetes—clinical examination and management: a narrative review
Published in Journal of Endocrinology, Metabolism and Diabetes of South Africa, 2021
AT Thompson, B Zipfel, C Aldous
The metatarsal parabola functions to provide stability during the stance and propulsive portion of gait, as weight is transferred to the metatarsal heads.18 Morton’s concept of lateral movement of pressure states that, if the first metatarsal is too short, it cannot assume the body weight in a balanced way and thus compensatory changes in foot posture might occur.18 A study found that patients with a Morton’s toe registered higher pressures beneath the second metatarsal (mean of 320 kPa) compared with a non-Morton foot control group (mean 243 kPa).29 A further study found that 60% of patients who presented with metatarsalgia (ball-of-the-foot pain) displayed lesser metatarsophalangeal joint instability.30 One study considered that the cause of lesser metatarsophalangeal joint symptoms was a deficit in first ray weight-bearing.31 In a critical analysis of Morton’s concepts, a review found support for Morton’s notion that weight can shift laterally in individuals who have a short first ray.32
A standalone computing system to classify human foot movements using machine learning techniques for ankle-foot prosthesis control
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Sagittal plane rotation at the ankle occurs when the foot is moved relative to the lower leg and vice-versa. When a person moves the top of the foot toward the shin, it is called dorsiflexion. While raising the heel off the ground as go up on the ball of the foot, the movement is termed as plantarflexion. Eversion and inversion are the frontal plane movements of the foot. The outward rotation of the sole is termed eversion, and the inward rotation of the sole is called inversion. When the leg is rotated toward the midline of the body in the transverse plane, it is called medial rotation, and when the rotation is away from the body's midline, it is termed lateral rotation.
Quantifying the similarity of 2D images using edge pixels: an application to the forensic comparison of footwear impressions
Published in Journal of Applied Statistics, 2021
Soyoung Park, Alicia Carriquiry
Suppose that the toe and/or heel regions are visible for Q and K so that the examiner can coarsely align the two images, for example by making the toe area the top and heel area the bottom of the images. If the toe or the heel areas of Q are not visible, then the examiner can still select a circular area in Q and plausibly matching areas in K to initiate the comparison. Here, we suppose that Q and K are roughly aligned toe to toe at the top of the image. Selection of the three circular areas of interest in Q can be performed manually (for example, by an examiner looking at the image on a computer) or automatically. If the latter, it may be reasonable to focus on regions of the outsole that are most likely to be in contact with the floor, and where we would expect to find the most wear and tear. Those regions include the ball of the foot and the heel, in a typical complete print. Consider the impression on the left panel of Figure 12. The three circles we select in Q are located on the left and right upper half of the outsole image and on the heel area as follows: In image Q, define x and y coordinates, and with radius equal to 50-pixel units. The other two circles are placed in the upper right quadrant and on the bottom left quadrant of the impression. Circle x and y coordinate ranges. Circles Q is a partial impression, the location of the three circular areas can be adjusted to fit within the latent impression.