Quadriceps Lag
The inability to maintain full knee extension against gravity when lifting the leg, indicating quadriceps weakness or inhibition.
Full Definition
Quadriceps lag refers to the measurable gap between passive and active knee extension, typically assessed with the patient supine and attempting to perform a straight leg raise. This phenomenon occurs when the quadriceps muscle cannot generate sufficient force to maintain the knee in full extension against gravity. It is commonly observed after knee injuries, surgeries, or periods of immobilization and serves as an important indicator of quadriceps function in rehabilitation. The presence and degree of quadriceps lag helps clinicians assess muscle strength, plan intervention strategies, and monitor recovery progress. Addressing quadriceps lag is essential for restoring normal knee function and preventing compensatory movement patterns.
Usage
Usage note: Document the degree of lag in degrees when measuring; distinguish from true muscle weakness.
In Context
- "The patient demonstrated a 15-degree quadriceps lag during the straight leg raise test." — Physical therapy assessment
- "Electrical muscle stimulation was initiated to address the persistent quadriceps lag post-ACL reconstruction." — Treatment plan documentation