If the difference between R1 and R2 is small, what does this indicate?

If the difference between R1 and R2 is small, what does this indicate?

• A. Spasticity
• B. Contracture
• C. Hypotonia
• D. Normal ROM

Answer: (B)

The difference between the angles R1 and R2 reflects how much of the motion limitation comes from velocity-dependent reflex activity (spasticity) versus fixed tissue shortening (contracture). R1 is the angle where a catch occurs with a fast stretch, while R2 is the full passive ROM with a slow stretch. If spasticity were driving the resistance, the fast stretch would stop the motion early (R1 is small) but the slow stretch would allow more range (R2 larger), giving a noticeable gap. A small difference means the range is similarly limited even when stretched slowly, indicating a structural shortening of the muscle-tendon unit or joint—contracture. So a small R1–R2 gap points to contracture rather than spasticity. Hypotonia would typically show reduced resistance and not this pattern of limitation, and normal ROM would not have a persistent restriction tied to tissue shortening.

The difference between the angles R1 and R2 reflects how much of the motion limitation comes from velocity-dependent reflex activity (spasticity) versus fixed tissue shortening (contracture). R1 is the angle where a catch occurs with a fast stretch, while R2 is the full passive ROM with a slow stretch. If spasticity were driving the resistance, the fast stretch would stop the motion early (R1 is small) but the slow stretch would allow more range (R2 larger), giving a noticeable gap. A small difference means the range is similarly limited even when stretched slowly, indicating a structural shortening of the muscle-tendon unit or joint—contracture. So a small R1–R2 gap points to contracture rather than spasticity. Hypotonia would typically show reduced resistance and not this pattern of limitation, and normal ROM would not have a persistent restriction tied to tissue shortening.