Inadequate knee flexion
during swing phase
A person who cannot shorten the lower limb sufficiently to clear it during swing phase often demonstrates one or more of a variety of swing phase deficits, including:
- Abduction or circumduction of the limb
- Pelvic elevation during swing (hip hiking), sometimes accompanied by contralateral trunk lean
- Vaulting, which involves excessive midstance plantar flexion on the contralateral (stance) limb
Therapists should recognize that these deficits' roots begin during PRESWING, the phase when the ground reaction force ordinarily produces a flexor moment that initiates knee flexion, which in turn permits the entire lower extremity to clear the ground during swing phase.
Inadequate knee flexion is due to one or several of the following preswing phase problems:
- Inadequate force in the hip flexors
- Inadequate force in the plantar flexors
- Inadequate forward rotation of the pelvis during preswing
- Inadequate ground reaction force
When clients' knee flexion is inadequate during swing, therapists' knowledge of gait compensations helps them target those aspects of the preswing movement patterns that they can change. Therapists can instruct clients to:
- use another muscle in a closed chain
They can activate hip flexors more forcefully to flex the knee in a closed chain.
- move so that they relocate the GRF vector, increasing the force's knee flexor moment.
They can rotate the pelvis forward appropriately during preswing .
- move so that they relocate the joint axis, increasing the ground reaction force's flexor moment at the knee.
They can forcefully activate the plantar flexors, and produce an appropriate heel rise during terminal stance.
- grade how quickly they shift their body weight off the preswing limb.
Even if the ground reaction force's location is appropriate, it still must be large enough to flex the knee.