Constant tension springs of long leg braces to assist the quadriceps femoris.

Patients with weakness or paralysis of the extensors of the knee, espe­ cially when this is associated with weakness or paralysis of the hip extensors, have great difficulty standing and walking. Many devices have been de­ signed to support the knees, ranging from simple gutter splints, plaster splints, and nonjointed bars to jointed knee braces with knee locks. Am­ bulation with a stiff knee is difficult for a person who has normal strength and is a great problem for a person with paresis or other disabilities. For this reason many attempts have been made to design a brace which allows flexion during sitting and flexion and support during walking, A knee joint allowing 2 to 4 degrees of extension beyond 180 degrees offers fairly good support to the patient with moderate weakness in both hip and knee when he is standing or walking, but it requires active muscular force, either in the knee extensors, themselves or in the hip extensors, to extend the knee.