Arm and Leg Synergies are Different and the Same

The hemiplegic arm is dominated by the flexion synergy while the hemiplegic leg is dominated by the extension synergy.  Muscles that straighten the knee and point the toes (extensors) are strong while muscles that bend the hip, knee, and ankle (flexors) are weak.  Yet arm and leg synergies are the same because both make it difficult to move a single joint.  When clients who are synergy-bound want to move a limb we have to move all the joints in the limb whether we want to or not.  

To point my toes I have to straighten my whole leg (photo on left).  To bend my ankle I have to bend my hip and knee (photo on right).  

Here is a synergy-related problem that my leg brace corrects.  My weak hip and knee flexors don't lift my leg high enough to clear my toes as I take a step.  My leg is mostly straight when I swing my leg to take a step so the extension synergy forces my toes to point.  Both weak hip flexors and the extension synergy produce foot drop which makes me stub my toes (photo on left).  The brace holds my toes and ankle up as I walk.  I faithfully wear my leg brace because it prevents falls.  Two trips to the emergency room after bad falls were enough for me. 

Here is another synergy-related problem that my brace corrects.  Hamstring muscles on the back of the thigh (the pink line) are supposed to keep my knee from snapping into a hyper extended position when I walk.  Hyper extension that occurs repeatedly can damage my knee.  My leg brace keeps my knee slightly bent (the green line) when I take a step to put weight on my hemiplegic foot.  I faithfully wear my leg brace because it defers the need for knee surgery.  I'm not interested in learning how to survive rehab after a knee replacement.