Ankle motions

Nonarticulated feet are typically the simplest and least expensive. The foot and ankle are combined in a single component, and shock absoiption and ankle motion are provided by the materials and structure of the foot. Since these feet are nonarticulated, diey are quiet and typically require little maintenance. These feet are also cosmetic, lightweight, and provide good shock absorption and limited inversion/eversion on uneven terrain. Disadvantages of nonarticulated feet are the limited range of plantarflexion/dorsiflexion, difficulty with inclines due to heel compression, lack of adjustability for different heel heights, and little torque-absorption capability. 

Continuous Passive Ankle Motion Device for Patient Undergoing Tibial Distraction... 

Taylor, G. J. (1988). Ankle motion after external fixation of tibial fractures. Journal of the Royal Sodety of Medidne, 81. 

The Irvine ankle prosthesis (also called the Howmedica total ankle) was a two-part, nonconstrained prosthesis with a UHMWPE tibial component and metal talar component that was designed in 1975 [28, 29] (Figure 11.8). It has been described as a multi-axial joint, which allows tibial motion about any of the three major axes and did not restrict rotational motion [18,19]. The device was cemented and permitted dorsiflexion/plantarflexion of 114 degrees and abduction/adduction of 40 degrees [29]. Initial clinical results were satisfactory [28]. A biomechanics study in cadaveric human ankle specimens indicated that it did not reproduce normal ankle motion because there was increased coupled motion and hysteresis in ankles with the prosthesis during plantarflexion/dorsiflexion and axial rotation [30]. 

Michelson ID, Schmidt GR, Mizel MS. Kinematics of a total arthroplasty of the ankle comparison to normal ankle motion. Foot Ankle Int 2000 April 21(4) 278-84. 

The joints affected most frequently by rheumatoid arthritis are the small joints of the hands, wrists, and feet (Fig. 89-3). In addition, elbows, shoulders, hips, knees, and ankles may be involved. Patients usually experience joint stiffness that typically is worse in the morning. The duration of stiffness tends to be correlated directly with disease activity, usually exceeds 30 minutes, and may persist all day. Chronic inflammation with lack of an adequate exercise program results in loss of range of motion, atrophy of muscles, weakness, and deformity. 

Fig. 3.5 Notional dielectric elastomer devices that can harvest human kinetic energy. Kinetic energy is available from vertical motion and from the negative work done at the ankles, knees, and hips. Energy harvesting devices can be strategically located in equipage to selectively harvest this energy in order to provide power to electronic systems. This arrangement will not hamper mobility and should actually reduce fatigue. [Source adapted from Infoscitex Corp. and SRI International]...

Joint motion of the talocrural joint has been studied to define the axes of rotation and their location with respect to specific anatomic landmarks (Table 49.2). The axis of motion of the talocrural joint essentially passes through the inferior tibia at the fibular and tibial maUeoh (Figure 49.3). Three types of motion have been used to describe the axes of rotation fixed, quasi-instantaneous, and instantaneous axes. The motion that occurs in the ankle joints consists of dorsiflexion and plantarflexion. Minimal or no transverse rotation takes place within the talocrural joint. The motion in the talocrural joint is intimately related to the motion in the talocalcaneal joint which is described next. 

Orthotic support in this context is the mechanical support, or orthosis, that enables the range of motion of a given joint or joints, but limiting movement beyond the norm. Such support can be found in the ankle detail of a walking boot or running shoe. Issues that must be addressed when using an orthotic component are ... 

Wu, G., Siegler, S., Allard, R, Kirtley, C. et al., ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion— Rart I Ankle, hip, and spine. /. Biomech., 35, pp. 543-548,2002. 

The human skeleton consists of both fused and individual bones supported and supplemented by ligaments, tendons, and skeletal muscles. The articular ligaments and tendons are the main parts holding together the joint(s). hr respect to the movement, there are freely moveable, partially moveable, and immovable joints. Synovial joints, the freely moveable ones, allow for a large range of motion and encompass wrists, knees, ankles, shoulders, and hips. 

STAUFFER, R.N., CHAO, E.Y.S. and BREWSTER, R.C. Force and motion analysis of the normal, diseased and prosthetic ankle joint, Clin. Orthop., 1977, 127. 189-196. 

None of the theoretical approaches outlined above considered adequately the cyclic nature of physiological loading and motion In synovial joints. Medley et al (6) Included such effects In their studies of ankle joint lubrication and they found that a reasonable approximation to the Instantaneous film thickness at any instant In the loading cycle could be obtained by means of an extended... 

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