Clinical evaluation of the effects of immobilization followed by remobilization and exercise on the metacarpophalangeal joint in horses.

The research investigates the impacts of immobilization, remobilization, and exercise on horse’s metacarpophalangeal joint (MPJ), showing that even after 8 weeks of exercise, post 7 weeks of joint immobilization, the joint function or other joint measures did not return to their original state.

Methodology

• The study involved 5 healthy horses.
• Each of these horses had one forelimb immobilized in a fiberglass cast for 7 weeks.
• After the period of immobilization, the cast was removed, and the horses were subjected to increasing amounts of exercise. This started with hand-walking and eventually led to treadmill exercises.
• The horses’ health was monitored throughout the study period using various methods including lameness examination, arthrocentesis of both MPJ, single-emulsion radiographic examination, nuclear scintigraphic examination, ground-reaction force-plate analysis, and computed tomographic examination.

Results

• After the cast removal, all horses displayed signs of lameness in the immobilized MPJ. While this condition improved slightly with exercise, it did not completely recover.
• Two weeks after cast removal, the force plate analysis identified a significant difference in peak forces between the immobilized limb and the non-immobilized limb.
• The study also found a significant decrease in the range of motion for the immobilized MPJ, and a corresponding increase in joint circumference, in comparison with the baseline values, during the exercise period.
• Osteopenia, a condition marked by a decrease in bone density, was observed in the immobilized limbs.
• Radiological observations showed increased uptake of radionucleotides within the bones of the immobilized MPJ after cast removal and at the end of the study.
• Additional findings included loss of mineral opacity, increased numbers of vascular channels in the subchondral bone, and thickening in the soft tissues of the immobilized MPJ.

Conclusions

• The study concludes that even after 8 weeks of enforced exercise following 7 weeks of joint immobilization, the joint function and measurements did not return to their pre-immobilization state.
• This indicates that the process of immobilization, followed by remobilization and exercise, leads to a lasting impact on the health and functionality of the horse’s MPJ.