The loading parameters in the canine hip were determined from multiple studies, involving the collection of kinematic and force plate data in vivo joint reaction force from an instrumented hip replacement prosthesis, and in vivo femoral cortical bone strain gauge data in different dogs. In the middle of the stance phase of gait the canine femur was flexed 110 degrees with respect to the pelvis and formed a 20 degree angle relative to the floor. At this point in the gait cycle, a line passing from the superior to the inferior aspect of the pubic symphysis was parallel to the floor. The joint reaction force measurements showed that the net force vector during midstance was directed inferiorly, posteriorly, and laterally, with a peak magnitude of up to 1.65 times the body weight. A torsional moment of 1.6 N m is exerted about the femoral shaft. In vivo strain data showed that during gait peak compressive strains of -300 to -502 microstrain were produced on the medial aspect of the femoral cortex and peak tensile strains of +250 to +458 midstrain were produced on the femoral cortex. At the midstance phase of gait, principal cortical bone strains were rotated up to 29 degrees relative to the long axis of the femur, suggesting torsional loads on the femur. These data in combination provide valuable insights on the loading parameters of the canine hip which can be used in future applications of the canine as a model for evaluating mechanically based phenomena such as bone ingrowth and remodeling or hip prostheses.
"Muscle excitation in the muscular sling of the forelimb may therefore be expected to reflect braking forces that pass through the proximal fulcrum as well as the absorption of collisional energy (Ruina et al., 2005; Bertram and Gutmann, 2009). This situation is different from that of the hindlimb, in which forces aligned with the limb axis can pass through the hip joint [e.g. in dogs (Page et al., 1993; Shahar and Banks-Sills, 2002)]. "
[Show abstract][Hide abstract] ABSTRACT: The extrinsic limb muscles perform locomotor work and must adapt their activity to changes in gait and locomotor speed, which can alter the work performed by, and forces transmitted across, the proximal fulcra of the limbs where these muscles operate. We recorded electromyographic activity of 23 extrinsic forelimb and hindlimb muscles and one trunk muscle in dogs while they walked, trotted and galloped on a level treadmill. Muscle activity indicates that the basic functions of the extrinsic limb muscles - protraction, retraction and trunk support - are conserved among gaits. The forelimb retains its strut-like behavior in all gaits, as indicated by both the relative inactivity of the retractor muscles (e.g. the pectoralis profundus and the latissimus dorsi) during stance and the protractor muscles (e.g. the pectoralis superficialis and the omotransversarius) in the first half of stance. The hindlimb functions as a propulsive lever in all gaits, as revealed by the similar timing of activity of retractors (e.g. the biceps femoris and the gluteus medius) during stance. Excitation increased in many hindlimb muscles in the order walk-trot-gallop, consistent with greater propulsive impulses in faster gaits. Many forelimb muscles, in contrast, showed the greatest excitation at trot, in accord with a shorter limb oscillation period, greater locomotor work performed by the forelimb and presumably greater absorption of collisional energy.
"During normal walking, maximal forces in dogs are 1.66% of body weight. When running or climbing stairs, hip loading is supposedly higher . Given that the forces on the human hip can increase to 2–3 times body weight, we accounted for sufficient loading by applying a maximal force of 1000 N to the dog bone (i.e., 3 times body weight ). "
[Show abstract][Hide abstract] ABSTRACT: Use of the proximal part of the femur in total hip arthroplasty enables preservation of the distal femur for later revisions. To use this advantage, different types of short-stem prosthesis have been developed in recent years. Although cementless hip arthroplasty is not common in the treatment of canine osteoarthritis, the use of cementless short-stems might be an alternative therapy. The new cementless short-stem prosthesis called Spiron® is self-tapping, and is constructed with a conical shape with threads. We measured the relative motion in the bone/prosthesis interface with specified loads in the femora of dogs to investigate two aspects: the primary stability of two systems of uncemented prosthesis with different principles of anchoring, and the theoretical use of the Spiron® in dog bone. We measured the cyclic behaviour (i.e., reversible, elastic), subsidence (i.e., irreversible, plastic, migration) and maximal applied load.
Twenty-four pairs of fresh femur bones from adult German shepherd dogs were used. After measuring the total bone mineral density (TBMD), 16 bones were used in each of the short-stem prosthesis group (group A), the Zweymuller prosthesis group (group B), and the no-prosthesis control group (group C). Micromotion between bone and prostheses was measured for 16,200 N axial load steps, beginning with 200 N and increasing to 3000 N (1600 cycles/femur). Simple analysis of variance and non-parametric tests were used to compare the groups.
The Spiron prosthesis had significantly less motion in the bone/prosthesis interface compared with the Zweymuller prosthesis.
The new principle of anchoring of the Spiron short-stem prosthesis may provide higher primary stability compared with conventional techniques. The findings of this study support the assumption that the use of the Spiron prosthesis to treat osteoarthritis in the dog is feasible.
Technology and health care: official journal of the European Society for Engineering and Medicine 01/2011; 19(4):271-82. DOI:10.3233/THC-2011-0634 · 0.70 Impact Factor
"Such anatomic differences potentially involve appreciably different effective joint loading (Alexander 2004). While joint contact forces have been extensively investigated in various traditional quadrupedal animal models of orthopaedic disorders (Page et al. 1993;Rumph et al. 1995;Bergmann et al. 1999), biomechanical investigations of avian species have focused more on comparative kinematics, energetics, and bone development (Carrano and Biewener 1999;Main and Biewener 2007). Therefore, an anatomy-based model of normal emu walking gait was developed to determine emu hip contact forces for comparison to those of the human. "
[Show abstract][Hide abstract] ABSTRACT: The emu is a large, (bipedal) flightless bird that potentially can be used to study various orthopaedic disorders in which load protection of the experimental limb is a limitation of quadrupedal models. An anatomy-based analysis of normal emu walking gait was undertaken to determine hip contact forces for comparison with human data. Kinematic and kinetic data captured for two laboratory-habituated emus were used to drive the model. Muscle attachment data were obtained by dissection, and bony geometries were obtained by CT scan. Inverse dynamics calculations at all major lower-limb joints were used in conjunction with optimization of muscle forces to determine hip contact forces. Like human walking gait, emu ground reaction forces showed a bimodal distribution over the course of the stance phase. Two-bird averaged maximum hip contact force was approximately 5.5 times body weight, directed nominally axially along the femur. This value is only modestly larger than optimization-based hip contact forces reported in literature for humans. The interspecies similarity in hip contact forces makes the emu a biomechanically attractive animal in which to model loading-dependent human orthopaedic hip disorders.
Journal of Biomechanics 02/2008; 41(4):770-8. DOI:10.1016/j.jbiomech.2007.11.022 · 2.75 Impact Factor
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