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Maximal Extension (maximal + extension)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

The effect of rising and sitting trot on back movements and head-neck position of the horse

EQUINE VETERINARY JOURNAL, Issue 5 2009
P. de COCQ
Summary Reason for performing study: During trot, the rider can either rise from the saddle during every stride or remain seated. Rising trot is used frequently because it is widely assumed that it decreases the loading of the equine back. This has, however, not been demonstrated in an objective study. Objective: To determine the effects of rising and sitting trot on the movements of the horse. Hypothesis: Sitting trot has more extending effect on the horse's back than rising trot and also results in a higher head and neck position. Methods: Twelve horses and one rider were used. Kinematic data were captured at trot during over ground locomotion under 3 conditions: unloaded, rising trot and sitting trot. Back movements were calculated using a previously described method with a correction for trunk position. Head-neck position was expressed as extension and flexion of C1, C3 and C6, and vertical displacement of C1 and the bit. Results: Sitting trot had an overall extending effect on the back of horses when compared to the unloaded situation. In rising trot: the maximal flexion of the back was similar to the unloaded situation, while the maximal extension was similar to sitting trot; lateral bending of the back was larger than during the unloaded situation and sitting trot; and the horses held their heads lower than in the other conditions. The angle of C6 was more flexed in rising than in sitting trot. Conclusions and clinical relevance: The back movement during rising trot showed characteristics of both sitting trot and the unloaded condition. As the same maximal extension of the back is reached during rising and sitting trot, there is no reason to believe that rising trot was less challenging for the back. [source]

Effects of 6° elevation of the heels on 3D kinematics of the distal portion of the forelimb in the walking horse

EQUINE VETERINARY JOURNAL, Issue 8 2004
H. CHATEAU
Summary Reasons for performing study: Understanding of the biomechanical effects of heel elevation remains incomplete because in vivo studies performed with skin markers do not measure the actual movements of the 3 digital joints. Objective: To quantify the effects of 6° heel wedge on the 3-dimensional movements of the 4 distal segments of the forelimb in the walking horse. Methods: Four healthy horses were used. Kinematics of the distal segments was measured invasively with a system based on ultrasonic triangulation. Three-dimensional rotations of the digital joints were calculated by use of a ,joint coordinate system' (JCS). Data obtained with heel wedges were compared to those obtained with standard shoes during the stance phase of the stride. Results: Heel wedges significantly increased maximal flexion of the proximal (PIPJ) and distal (DIPJ) interphalangeal joints and maximal extension (mean ± s.d. +0.8 ± 0.3°) of the metacarpophalangeal joint (MPJ). Extension of the PIPJ and DIPJ was decreased at heel-off. Few effects were observed in extrasagittal planes of movement. Conclusions: Heel wedges affect the sagittal plane kinematics of the 3 digital joints. Potential relevance: Controversial effects previously observed on the MPJ may be explained by the substantial involvement of the PIPJ, which was wrongly neglected in previous studies performed on the moving horse. [source]

Sinus augmentation analysis revised: the gradient of graft consolidation

CLINICAL ORAL IMPLANTS RESEARCH, Issue 10 2009
Dieter Busenlechner
Abstract Objective: Graft consolidation follows a gradient that reflects the properties of bone substitutes at sites of sinus augmentation. Here we present an analytical method to investigate the process of graft consolidation taking the distance from the maxillary host bone into account. Material and methods: We therefore evaluated histological specimens, 6 and 12 weeks after the sinus of minipigs was augmented with Bio-Oss®, a deproteinized bovine bone mineral, and Ostim®, an aqueous paste of synthetic nanoparticular hydroxyapatite. A curve was drawn that represents the changes in histomorphometric parameters within a given distance from the maxillary host bone. Results: Based on this curve, three regions of interest were defined: R1 (0,1 mm) the bridging distance where new bone is laid onto the host bone, R2 (2,3 mm) a region of osteoconduction where new bone exclusively grows on the biomaterial, R3 (4,5 mm) and a region of osteoconduction where bone formation has reached its maximal extension. Qualitative and quantitative analysis of the three regions can reveal differences in graft consolidation, depending on the bone substitutes and the observation period [Bone volume (BV) per tissue volume after 6 weeks: R1: 19±8.4% for Bio-Oss® and 42.9±13.2% for Ostim® (P=0.03), R2: 3±2.4% for Bio-Oss® and 14.7±9.5% for Ostim® (P=0.03), R3: 5±4.1% for Bio-Oss® and 5.3±5.3% for Ostim® (P=0.86). BV per tissue volume after 12 weeks: R1: 38.0±13.3% for Bio-Oss® and 53.3±6.6 for Ostim® (P=0.04), R2: 14±12.2 for Bio-Oss® and 26.4±11 for Ostim® (P=0.18), R3: 6.6±7 for Bio-Oss® and 10.7±5.8 for Ostim® (P=0.32) after 12 weeks]. Conclusion: Based on the graft consolidation gradient, the impact of bone substitutes to modulate the process of bone formation and the kinetic of degradation within a distinct region of the augmented sinus can be investigated. [source]