Changes

==='''Kinds of fractures'''===

==='''Kinds of fractures'''===

   

   

Bone, we have noted, is stronger under compression than under tension, while shear is intermediate.  Appropriate combinations of forces cause tensile fractures (Fig. 3.4 A) in bone mainly at the sites of attachment of tendons and ligaments.  Common sites of fracture are, in the horse, the proximal ulna, the patella, the proximal sesamoids, the calcaneus and the accessory carpal bone.  Such fractures are usually transverse.

Bone, we have noted, is stronger under compression than under tension, while shear is intermediate.  Appropriate combinations of forces cause tensile fractures (Fig. 3.4 A) in bone mainly at the sites of attachment of tendons and ligaments.  Common sites of fracture are, in the horse, the proximal ulna, the patella, the proximal sesamoids, the calcaneus and the accessory carpal bone.  Such fractures are usually transverse.

Compression fractures, (Fig. 3.4 B) by contrast, are usually oblique, at an angle of 45° that corresponds to the plane of maximal shear stress due to the compressive load.   

Compression fractures, (Fig. 3.4 B) by contrast, are usually oblique, at an angle of 45° that corresponds to the plane of maximal shear stress due to the compressive load.   

In torsion fractures, (Fig. 3.4 D) shear stress occurs over the entire shaft of a long bone, and is greatest at the periosteal surface.  The result is a spiralling fracture.

In torsion fractures, (Fig. 3.4 D) shear stress occurs over the entire shaft of a long bone, and is greatest at the periosteal surface.  The result is a spiralling fracture.

:::::'''Fig.3.4 Ways in which a long bone may fracture'''

:::::'''Fig.3.4 Ways in which a long bone may fracture'''