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- Author or Editor: Marc H. Ratzlaff x
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Abstract
Objective—To define relationships between hoofacceleration patterns of galloping horses and dynamic properties of the track.
Animals—8 Thoroughbred horses without lameness.
Procedure—Acceleration-time curves were recorded by use of accelerometers attached to each hoof as each horse galloped over the track straightaway. Four sessions were conducted for each horse, with the track surface modified by sequentially adding water before each session. These acceleration-time curves were analyzed to determine peak accelerations during the support phase of the stride. Track dynamic properties (hardness, rebound, deceleration rate, rebound rate, and penetration) were recorded with a track-testing device. Moisture content and dry density were measured from soil samples. Stepwise multiple regression was used to identify relationships between hoof-acceleration variables and track dynamic properties.
Results—Track rebound rate was most consistently related to hoof variables, especially through an inverse relationship with negative acceleration peaks for all hooves. Also, rebound rate was related to initial acceleration peak during propulsion of the hooves of the forelimb and the nonlead hind limb as well as to the second acceleration peak during propulsion of the lead hooves of the hind limb and nonlead forelimb.
Conclusions and Clinical Relevance—The inverse relationship between track rebound rate and negative acceleration peaks for all hooves reflects the most important dynamic property of a track. Any factor that reduces negative acceleration of the hooves will increase stride efficiency by allowing smoother transition from retardation to propulsion and therefore may be important in determining the safety of racing surfaces. (Am J Vet Res 2005;66:589–595)
Abstract
Objective—–To compare transfixation and standard full-limb casts for prevention of in vitro displacement of a mid-diaphyseal third metacarpal osteotomy site in horses.
Sample Population—6 forelimbs from 6 horses euthanatized for reasons not related to the musculoskeletal system.
Procedure—A 30° osteotomy was performed in the mid-diaphysis of the third metacarpal bone. Two 4.5-mm cortical bone screws were placed across the osteotomy site to maintain alignment during casting. Two 6.35-mm Steinmann pins were placed from a lateral-to-medial direction in the distal aspect of the radius. A full-limb cast that incorporated the pins was applied. An extensometer was positioned in the osteotomy site through a window placed in the dorsal aspect of the cast, and after removal of the screws, displacement was recorded while the limb was axially loaded to 5,340 N (1,200 lb). Pins were removed, and the standard full-limb cast was tested in a similar fashion.
Results—The transfixation cast significantly reduced displacement across the osteotomy site at 445 N (100 lb), 1,112 N (250 lb), 2,224 N (500 lb), and 4,448 N (1,000 lb), compared with the standard cast.
Conclusion and Clinical Relevance—A full-limb transfixation cast provides significantly greater resistance than a standard full-limb cast against axial collapse of a mid-diaphyseal third metacarpal osteotomy site when the bone is placed under axial compression. Placement of full-limb transfixation casts should be considered for the management of unstable fractures of the third metacarpal bone in horses. (Am J Vet Res 2000;61:1633–1635)
