Computed tomographic imaging of subchondral fatigue cracks in the distal end of the third metacarpal bone in the thoroughbred racehorse can predict crack micromotion in an ex-vivo model.

Articular stress fracture arising from the distal end of the third metacarpal bone (MC3) is a common serious injury in Thoroughbred racehorses. Currently, there is no method for predicting fracture risk clinically. We describe an ex-vivo biomechanical model in which we measured subchondral crack micromotion under compressive loading that modeled high speed running.

Arthroscopic assessment of stifle synovitis in dogs with cranial cruciate ligament rupture.

Cranial cruciate ligament rupture (CR) is a degenerative condition in dogs that typically has a non-contact mechanism. Subsequent contralateral rupture often develops in dogs with unilateral CR. Synovitis severity is an important factor that promotes ligament degradation.

Systemic effects of ulna loading in male rats during functional adaptation.

Functional skeletal adaptation is thought to be a local phenomenon controlled by osteoctyes. However, the nervous system also may have regulatory effects on adaptation. The aim of this study was to determine the effects of loading of a single bone on adaptation of other appendicular long bones and whether these responses were neuronally regulated.

Functional adaptation to loading of a single bone is neuronally regulated and involves multiple bones.

Regulation of load-induced bone formation is considered a local phenomenon controlled by osteocytes, although it has also been hypothesized that functional adaptation may be neuronally regulated. The aim of this study was to examine bone formation in multiple bones, in response to loading of a single bone, and to determine whether adaptation may be neuronally regulated. Load-induced responses in the left and right ulnas and humeri were determined after loading of the right ulna in male Sprague-Dawley rats (69 +/- 16 days of age).

Effect of short-term treatment with alendronate on ulnar bone adaptation to cyclic fatigue loading in rats.

Targeted remodeling of fatigue-injured bone involves activation of osteoclastic resorption followed by local bone formation by osteoblasts. We studied the effect of parenteral alendronate (ALN) on bone adaptation to cyclic fatigue. The ulnae of 140 rats were cyclically loaded unilaterally until 40% loss of stiffness developed.

Effect of fatigue loading and associated matrix microdamage on bone blood flow and interstitial fluid flow.

Functional adaptation of bone to cyclic fatigue involves a complex physiological response that is targeted to sites of microdamage. The mechanisms that regulate this process are not understood, although lacunocanalicular interstitial fluid flow is likely important. We investigated the effect of a single period of cyclic fatigue on bone blood flow and interstitial fluid flow.

Progressive arthropathy in mice with a targeted disruption of the Mop3/Bmal-1 locus.

Disruption of the murine Mop3 (also known as Bmal1 or Arntl) locus results in a loss of behavioral and molecular circadian rhythms. Although Mop3 null mice do not display anomalies in early development, they do display reduced activity as they age. In an effort to explain this decreased activity, we characterized the physiological and anatomical changes that occurred with age.

Effect of focused and radial extracorporeal shock wave therapy on equine bone microdamage.

Objectives: To determine whether bone microcracks are altered after application of focused and radial extracorporeal shock wave therapy (ESWT) to the equine distal limb.

Study Design: An ex vivo experimental model.

Sample Population: A contralateral limb specimen was obtained from 11 Thoroughbred racehorses with a unilateral catastrophic injury.

Fatigue microdamage in the radial predilection site for osteosarcoma in dogs.

Objective: To evaluate whether body size and anatomic site influence the quantity of bone microdamage in dogs without osteosarcoma (OS).

Sample Population: Pairs of radii were collected from 10 small dogs (< 15 kg) and 10 large dogs (> 25 kg).

Procedure: Specimens were stained in basic fuchsin for bone microdamage.