Joint Contracture Resulting From a Two-Hour Daily Joint Immobility: An Experimental Study in Rats

Area of Science:

• Biomedical Engineering
• Physiology
• Orthopedics

Background:

• Joint contracture prevention often emphasizes exercise duration, but effective methods remain elusive.
• Limited joint movement is suspected in contracture development, yet this link lacks quantitative evidence.
• Hospitalized patients and the elderly may face prolonged immobility (≥2 hours) due to repositioning schedules.

Purpose of the Study:

• To investigate if two hours of daily joint immobility over two weeks induces joint contractures.
• To assess contracture development in a non-weight-bearing hindlimb suspension model.
• To quantitatively evaluate the relationship between short-term immobility and joint contracture.

Main Methods:

• Six Wistar rats underwent hindlimb suspension with one hindlimb immobilized in plantar flexion for two hours daily over two weeks.
• The contralateral hindlimb served as the control group with unrestricted movement.
• Measurements included ankle dorsiflexion angle, muscle fiber cross-sectional area, and soleus muscle relative weight.

Main Results:

• A significant decrease in ankle dorsiflexion range of motion was observed in the immobilized group compared to the control.
• The immobilized ankle dorsiflexion angle reduced by 9.8% over two weeks, versus 1.7% in the control.
• Muscle fiber cross-sectional area and soleus muscle relative weight also showed significant changes.

Conclusions:

• Two hours of daily joint immobility, coupled with hindlimb suspension, is associated with reduced ankle range of motion.
• This model suggests that even short, intermittent immobility periods can contribute to joint contracture development.
• The findings offer a novel experimental perspective distinct from continuous immobilization models.