Contractures secondary to immobility: Is the restriction articular or muscular? An experimental longitudinal study in the rat knee  Guy Trudel, MD, Hans K. Uhthoff, MD  Archives of Physical Medicine and Rehabilitation  Volume 81, Issue 1, Pages 6-13 (January 2000) DOI: 10.1016/S0003-9993(00)90213-2 Copyright © 2000 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 1 Components of contractures in immobilized knee joints over time. (A) Data in degrees. With the increasing times of immobilization, the arthrogenic component increased sharply. Error bars = 1 SEM. Asterisks indicate a significant contribution to the difference in ROM between immobilized and control knees. (B) Data in percentages of the total restriction: ■, myogenic total; ▩, arthrogenic total. Past the 2-week mark, the arthrogenic component constituted more than 80% of the total restriction in ROM. Torque = 1,060g-cm. Archives of Physical Medicine and Rehabilitation 2000 81, 6-13DOI: (10.1016/S0003-9993(00)90213-2) Copyright © 2000 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 2 Extension. Components of the limitation in extension angular displacement in immobilized knee joints over time. (A) Data in degrees. The data are very similar to the data on total restriction indicating that most of the changes took place in extension (not in flexion). Error bars = 1 SEM. Asterisks indicate a significant contribution to the difference in ROM between immobilized and control knees. (B) Data in percentages: ■, myogenic extension; ▩, arthrogenic extension. A progressive increase in the arthrogenic component is seen with increasing periods of immobilization. Even after 32 weeks of immobility, a plateau was not reached. Normalized data. Torque = 1,060g-cm. Archives of Physical Medicine and Rehabilitation 2000 81, 6-13DOI: (10.1016/S0003-9993(00)90213-2) Copyright © 2000 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 3 Flexion. Components of the limitation in flexion angular displacement in immobilized knee joints over time: —●—, combined flexion; --●--, arthrogenic flexion;    ●   , myogenic flexion. Changes in flexion were of much smaller magnitude than changes in extension. In flexion, negative numbers were obtained in situations where the immobilized animals gained more angular displacement than the controls. Normalized data. Torque = 1,060g-cm. Error bars = 1 SEM. Asterisks indicate a significant contribution to the difference in ROM between immobilized and control knees. Archives of Physical Medicine and Rehabilitation 2000 81, 6-13DOI: (10.1016/S0003-9993(00)90213-2) Copyright © 2000 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 4 Effect of torque on the proportion of each component of contractures: ■, arthrogenic restriction; ▩, myogenic restriction. Increasing torques led to a smaller proportion of the arthrogenic component of contractures. See the text for explanations as to which torque data are most applicable to clinical situations. Data combined from all time points (from 2 to 32 weeks). Archives of Physical Medicine and Rehabilitation 2000 81, 6-13DOI: (10.1016/S0003-9993(00)90213-2) Copyright © 2000 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions