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  • Author or Editor: Philip D. van Harreveld x
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Abstract

Objective—To determine microradiographic appearance, bone histomorphometry, and mineral density of the long bones of the metacarpophalangeal joint in horses after immobilization followed by remobilization.

Animals—5 healthy horses.

Procedure—One forelimb of each horse was immobilized in a fiberglass cast for 7 weeks, followed by 8 weeks of increasing exercise. Calcein and oxytetracycline were administered IV during the immobilization and exercise phases, respectively, for bone labeling and analysis after euthanasia. Sagittal sections of metacarpal bones and proximal phalanges were examined via radiography, dual energy x-ray absorptiometry, histomorphometry, and bone label analysis.

Results—Radiography revealed loss of bone mineral opacity in the subarticular regions of the immobilized metacarpal bones and phalanges and subchondral lesions in metacarpal bones in 2 horses. In phalanges, a significant decrease in subarticular volumetric bone mineral density was detected. There was significantly less bone volume and calcein-labeled bone surface and more vascular volume and oxytetracycline-labeled bone surface in immobilized phalanges, compared with contralateral phalanges.

Conclusions and Clinical Relevance—Eight weeks of exercise after single-limb immobilization is insufficient for recovery of volumetric bone mineral density. During immobilization and remobilization, the subchondral and trabecular bone appear to be actively remodeling. (Am J Vet Res 2002;63:276–281)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate clinical effects of immobilization followed by remobilization and exercise on the metacarpophalangeal joint (MPJ) in horses.

Animals—5 healthy horses.

Procedure—After lameness, radiographic, and force plate examinations to determine musculoskeletal health, 1 forelimb of each horse was immobilized in a fiberglass cast for 7 weeks, followed by cast removal and increasing amounts of exercise, beginning with hand-walking and ending with treadmill exercise. Lameness examination, arthrocentesis of both MPJ, single-emulsion radiographic examination, nuclear scintigraphic examination, ground-reaction force-plate analysis, and computed tomographic examination were done at various times during the study.

Results—All horses were lame in the immobilized MPJ after cast removal; lameness improved slightly with exercise. Force plate analysis revealed a significant difference in peak forces between immobilized and contralateral limbs 2 weeks after cast removal. Range of motion of the immobilized MPJ was significantly decreased, and joint circumference was significantly increased, compared with baseline values, during the exercise period. Osteopenia was subjectively detected in the immobilized limbs. Significant increase in the uptake of radionucleotide within bones of the immobilized MPJ after cast removal and at the end of the study were detected. Loss of mineral opacity, increased vascular channels in the subchondral bone, and thickening within the soft tissues of the immobilized MPJ were detected.

Conclusions and Clinical Relevance—Results indicate that 8 weeks of enforced exercise after 7 weeks of joint immobilization did not restore joint function or values for various joint measurements determined prior to immobilization. (Am J Vet Res 2002;63:282–288)

Full access
in American Journal of Veterinary Research