Contractures secondary to immobility: is the restriction articular or muscular? An experimental longitudinal study in the rat knee.

date: 01/01/2000
author: Trudel G, Uhthoff HK.
publication: Arch Phys Med Rehabilitation. 2000 Jan;81(1):6-13.
pubmed_ID: 10638868

OBJECTIVES: To measure articular structures’ contribution to the limitation of range of motion after joint immobility. STUDY DESIGN: Experimental, controlled study involving 40 adult rats that had one knee joint immobilized in flexion for durations of 2, 4, 8, 16, and 32 weeks; 20 rats underwent a sham procedure. The angular displacement was measured both in flexion and extension at three different torques. Myotomy of transarticular muscles allowed isolation of the arthrogenic component of the contracture. RESULTS: A contracture developed in all immobilized knees. The articular structures were incrementally responsible for the limitation in range of motion (from 12.6 degrees +/-6.7 degrees at 2 weeks to 51.4 degrees +/-5.4 degrees at 32 weeks). The myogenic restriction proportionately decreased over time (from 20.1 degrees +/-8.4 degrees at 2 weeks to only 0.8 degrees +/-7.2 degrees at 32 weeks). The increase in the arthrogenic component of contracture was predominant in extension. CONCLUSION: This study quantified the increasing role of arthrogenic changes in limiting the range of motion of joints after immobility, especially as the period of immobility extended past 2 weeks. These data provide a better understanding of joint contracture development and can be used to guide therapeutic approaches.