The hindlimb in walking horses: 2. Net joint moments and joint powers.
ABSTRACT The objective of the study was to describe net joint moments and joint powers in the equine hindlimb during walking. The subjects were 5 sound horses. Kinematic and force data were collected synchronously and combined with morphometric information to determine net joint moments at each hindlimb joint throughout stance and swing. The results showed that the net joint moment was on the caudal/plantar side of all hindlimb joints at the start of stance when the limb was being actively retracted. It moved to the cranial/dorsal side around 24% stride at the hip and stifle and in terminal stance at the more distal joints. It remained on the cranial/dorsal side of all joints during the first half of swing to provide active limb protraction, then moved to the caudal/plantar aspect to reverse the direction of limb motion prior to ground contact. The hip joint was the main source of energy generation throughout the stride. It was assisted by the tarsal joint in both stance and swing phases and by the fetlock joint during the stance phase. The coffin joint acted as an energy damper during stance, whereas the stifle joint absorbed almost equal amounts of energy in the stance and swing phases. The coffin and fetlock joints absorbed energy as the limb was protracted and retracted during the swing phase, suggesting that their movements were driven by inertial forces. Future studies will apply these findings to detect changes in the energy profiles due to specific soft tissue injuries.
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ABSTRACT: Leg problems are a burden to both the pigs and the farmers in modern pig production, because leg problems decrease the welfare of the pigs, they are highly prevalent and one of the main reasons for removing the pigs prematurely from production. One of the principal causes of leg problems is the pig pen floor, or rather inappropriate floors. Especially inadequate frictional properties leading to slippery floor conditions may contribute to these leg problems. Until now the effect of floor condition on the gait of pigs has not been characterised scientifically. The overall objectives of the present thesis were to characterize the gait of pigs biomechanically and to examine the effect of floor condition on the pigs’ gait. These objectives were achieved via two types of studies, namely morphometric studies of the body segment parameters and joint rotation axes of pigs’ limbs, and a biomechanical analysis of walking pigs. By combining the data from these studies through inverse dynamics the joint loads in the limbs of walking pigs can be calculated. The thesis is based on three papers which more specifically aimed to: 1) Measure the body segment parameters and determine the joint rotation axes of pigs’ limbs; 2) Characterize the walk of pigs on dry solid concrete floor, evaluate whether pigs modify their gait according to floor condition, and suggest a coefficient of friction that ensures pigs safe walking on solid concrete floors; 3) Calculate the net joint forces and moments of the fore- and hindlimb joints of pigs walking on solid concrete floor and examine the effect of floor condition on the net joint reaction forces and joint moments. The results showed that the joint rotation axes were located mainly at or near the attachment site of the lateral collateral ligament of the joints. The body segment parameters revealed that the pigs’ forelimb was lighter and shorter than their hindlimb. Furthermore, the biomechanical analysis showed that on wet and greasy floor conditions the pigs lowered the walking speed and the peak utilized coefficient of friction compared to dry floor. Moreover, the pigs shortened the progression length, i.e. step length, and prolonged the stance phase duration on greasy floor. The inverse dynamics revealed that the forelimb peak horizontal joint reaction force and the hindlimb minimum horizontal joint reaction force were lowest on greasy floor. Also the forelimb joint moments were displaced to a lower level on greasy floor compared to dry and wet floors. In addition the gait analysis showed that during walk the forelimbs carried more body weight and received higher peak ground reaction forces than the hindlimbs. Finally the hindlimb stance phase was shorter than the stance phase of the forelimbs. In conclusion this thesis presents the first experimental data on the joint rotation axes and body segment parameters of pigs’ limbs. The locations of the joint rotation axes were described relative to bony landmarks and may serve as skin marker positions in kinematics. Furthermore the quantification of the body segment parameters enables inverse dynamic analysis of the locomotion of pigs. Moreover, the biomechanical analysis showed that floor condition did affect the pigs’ gait in several ways. Among other things the pigs lowered their walking speed and peak utilized coefficient of friction, shortened their steps and prolonged their stance phase duration on greasy and potentially slippery floor. The inverse dynamics revealed that, as a consequence of these gait adaptations, numerous joint parameters were affected by floor condition, especially in the forelimbs. Overall, greasy floor appeared the most slippery condition to the pigs, whereas wet floor was intermediate of dry and greasy conditions. The gait analysis also revealed some biomechanical differences between the limbs, as the forelimbs carried more weight and had longer stance phases than the hindlimbs, consequently the pigs’ forelimb joints responded more markedly to floor condition than their hindlimb joints. Finally the gait analysis indicated that a high static coefficient of friction is needed to prevent pigs from slipping on dry concrete floors.10/2007, Degree: Ph.D., Supervisor: B.R. Jensen, B.L. Nielsen, B. Jørgensen
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ABSTRACT: Functional recovery in animal models of nervous system disorders commonly involves behavioural compensation, in which animals alter the use of their limbs after injury, making it difficult to distinguish 'true' recovery from substitution of novel movements. The purpose of this study is to investigate how abnormal movements are produced by using biomechanical assessment of limb joint motion, an approach commonly used to diagnose human pathological gait. Rats were trained to cross a runway whilst kinetic (ground reaction forces) and kinematic (limb segment positions) data were synchronously recorded. Inverse dynamic analysis was used to calculate limb joint moments, or torques, and joint mechanical power throughout the stride for major joints of the forelimbs and hindlimbs, both before and after denervation of a major ankle extensor muscle. Before surgery, rats moved with joint moment and power profiles comparable to other quadrupeds, with differences attributable to species variation in limb posture. After surgery, rats trotted asymmetrically, with a near plantigrade stance of the left hindlimb. Surprisingly, ankle joint moments and power were largely preserved, with dramatic reductions in range of motion and joint moments at the proximal joints of the affected limb. Stiffening of the proximal limb compensated for increased compliance at the ankle but decreased the total mechanical work done by the injured limb. In turn, more work was done by the opposite, i.e. uninjured, hindlimb. This is the first study to quantify the biomechanical adjustments made within and between limbs in laboratory rodents after nervous system injury.Behavioural brain research 04/2012; 229(2):391-400. · 3.22 Impact Factor
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ABSTRACT: Subjective evaluation of canine gait has been used for many years. However, our ability to perceive minute details during the gait cycle can be difficult and in some respects impossible even for the most talented gait specialist. The evolution of computer technology in computer assisted gait analysis over the past 20 years has improved the ability to quantitatively define temporospatial gait characteristics. These technological advances and new developments in methodological approaches have assisted researchers and clinicians in gaining a better understanding of canine locomotion. The use of kinematic and kinetic analysis has been validated as a useful tool in veterinary medicine. This paper is an overview of the kinematic and kinetic analytical techniques of the last decade.The Veterinary Journal 11/2008; · 2.42 Impact Factor