The functional anatomy of the pelvic limb of the ostrich ( Struthio camelus ) was investigated in order to assess musculoskeletal specialization related to locomotor performance. The pelvic limbs of ten ostriches were dissected and detailed measurements of all muscle tendon units of the pelvic limb were made, including muscle mass, muscle length, fascicle length, pennation angle, tendon mass and tendon length. From these measurements other muscle properties such as muscle volume, physiological cross-sectional area (PCSA), tendon cross-sectional area, maximum isometric muscle force and tendon stress were derived, using standard relationships and published muscle data.Larger muscles tended to be located more proximally and had longer fascicle lengths and lower pennation angles.This led to an expected proximal to distal reduction in total muscle mass. An exception to this trend was the gastrocnemius muscle, which was found to have the largest volume and PCSA and also had the highest capacity for both force and power production. Generally high-power muscles were located more proximally in the limb, while some small distal muscles (tibialis cranialis and flexor perforatus digiti III), with short fibres, were found to have very high force generation capacities. The greatest proportion of pelvic muscle volume was for the hip extensors, while the highest capacity for force generation was observed in the extensors of the ankle, many of which were also in series with long tendons and thus were functionally suited to elastic energy storage.

Muscle moment arms were measured for major muscles of the pelvic limb of the ostrich ( Struthio camelus ) in order to assess specific functional behaviour and to apply this to locomotor performance. Pelvic limbs of six juvenile ostriches were used for this study. The tendon travel technique was used to measure moment arms of 21 muscles at the hip, knee, ankle and metatarsophalangeal joints throughout the ranges of motion observed during level running. Six of the 21 muscles measured were found to have moment arms that did not change with joint angle, whilst the remainder all demonstrated angle-dependent changes for at least one of the joints crossed. Moment arm lengths tended to be longest for the large proximal muscles, whilst the largest relative changes were found for the moment arms of the distal muscles. For muscles where moment arm varied with joint angle: all hip muscles were found to have increasing moment arms with extension of the joint, knee flexors were found to have moment arms that increased with extension, knee extensor moment arms were found to increase with flexion and ankle extensor moment arms increased with extension. The greatest relative changes were observed in the flexors of the metatarsophalangeal joint, for which a three-fold increase in moment arm was observed from flexion to full extension. Changes in muscle moment arm through the range of motion studied appear to optimize muscle function during stance phase, increasing the effective mechanical advantage of these muscles.

A mobile system that reliably detects and quantifies hindlimb lameness in horses during unconstrained locomotion could be a valuable tool to perform an evidence-based assessment of lameness in horses in a clinical setting, e.g. before and after nerve blocks or before and after surgery.

SUMMARYKinematic and kinetic parameters of running gait were investigated through growth in the ostrich, from two weeks up to 10 months of age, in order to investigate the effects of increasing body size. Ontogenetic scaling relationships were compared with published scaling relationships found to exist with increasing body size between species to determine whether dynamic similarity is maintained during growth. During the study, ostrich mass ( ), significantly exceeding the close to geometric scaling observed between mammalian and avian species of increasing body size. Scaling of kinematic variables largely agreed with predicted scaling for increasing size and demonstrated relationships close to dynamic similarity and, as such, ontogenetic scaling of locomotor parameters was similar to that observed with increasing body mass between species. However, the ways in which these scaling trends were achieved were very different, with ontogenetic scaling of locomotor mechanics largely resulting from simple scaling of the limb segments rather than postural changes, likely to be due to developmental constraints. Small deviations from dynamic similarity of kinematic parameters and a reduction in the predicted scaling of limb stiffness (ϰM b 0.59 ) were found to be accounted for by the positive allometric scaling of the limb during growth.

SUMMARYAnimals in their natural environments are confronted with a regular need to perform rapid accelerations (for example when escaping from predators or chasing prey). Such acceleration requires net positive mechanical work to be performed on the centre of mass by skeletal muscle. Here we determined how pelvic limb joints contribute to the mechanical work and power that are required for acceleration in galloping quadrupeds. In addition, we considered what, if any, biomechanical strategies exist to enable effective acceleration to be achieved. Simultaneous kinematic and kinetic data were collected for racing greyhounds undergoing a range of low to high accelerations. From these data, joint moments and joint powers were calculated for individual hindlimb joints. In addition, the mean effective mechanical advantage (EMA) of the limb and the ʻgear ratioʼ of each joint throughout stance were calculated. Greatest increases in joint work and power with acceleration appeared at the hip and hock joints, particularly in the lead limb. Largest increases in absolute positive joint work occurred at the hip, consistent with the hypothesis that quadrupeds power locomotion by torque about the hip. In addition, hindlimb EMA decreased substantially with increased acceleration -a potential strategy to increase stance time and thus ground impulses for a given peak force. This mechanism may also increase the mechanical advantage for applying the horizontal forces necessary for acceleration.

ostriches did use acceleration or braking forces to control body rotation, their morphology allowed for both crossovers and sidesteps to be accomplished with minimal net acceleratory/braking force production. Moreover, body roll and ab/adduction of the leg shifted the foot position away from the turn direction, reducing the acceleratory/braking forces required to prevent under-or over-rotation and aligning the leg with the ground reaction force.

Objective-To compare the mechanical properties and interoperator variabilities of 2 crimp clamp systems for extracapsular, fabello-tibial, nylon loop stabilization of the cranial cruciate ligamentdeficient stifle in dogs. Study Design-In vitro mechanical testing. Methods-Three operators with different grip strengths each secured 20 standardized nylon loops using stainless-steel crimp clamps: 10 using a Veterinary Instrumentation system (45 kg [100 lb] test nylon leader line, 12 mm crimp clamps) and 10 using a Securos system (36 kg [80 lb] test nylon leader line, 36 kg [80 lb] crimp clamps). Loops were tensile loaded to failure in a materials testing machine. Results-Mean ultimate load and mean stiffness were significantly higher for the Securos (336.9 N, 60.6 N/mm) than for the Veterinary Instrumentation system (113.8 N, 37.0 N/mm). For both systems, ultimate load was subject to interoperator variability. Conclusions-The Securos loops were significantly stronger and stiffer than the Veterinary Instrumentation loops for all operators, but significant differences between operators for ultimate load existed for both systems. Clinical Relevance-Securos fabello-tibial sutures will withstand greater loads than Veterinary Instrumentation sutures and this is particularly true for sutures created by surgeons with reduced grip strength. It may be necessary to use more than 1 Veterinary Instrumentation suture to match the ultimate load and stiffness of a Securos suture. r

The hand tightening method described is a valuable technique for unassisted surgeons without access to tensioning devices.