1. Kinematic effects on gait of a newly designed ankle-foot orthosis with oil damper resistance: A case series of 2 patients with hemiplegia 
Osamu Yokoyama, MD, Hironobu Sashika, MD, Akiyoshi Hagiwara, RPT, Sumiko Yamamoto, PhD, Tadashi Yasui, BEng 
Archives of Physical Medicine and Rehabilitation 
Volume 86, Issue 1, Pages (January 2005)
DOI: /j.apmr

2. Fig 1
The new AFO with (A) an oil damper and (B) a schematic design of the ankle joint with the oil damper unit. The ankle joint consists of the oil damper unit (1), a metal plate (2), and a ring portion (3). A hydraulic cylinder (4) was used as the oil damper. An adjustment screw (5) controls the rate of oil flow by changing the diameter of orifices. A spring (6) assists with dorsiflexion. The rod cap (7) is attached for setting the initial angle of the ankle joint.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )

3. Fig 2
Schematic design of the hydraulic cylinder in the oil damper. As the piston (1) moves into the oil-filled cylinder (2) with rotating plantarflexion of the ankle joint, the oil is forced out through orifices (3) of the cylinder wall. As the viscosity of the fluid increases and the diameter of the orifices decreases, the flow rate through the orifices slows, allowing greater resistance to ankle plantarflexion at heel strike. Oil is returned into the cylinder through check valves in the piston (4) without resistance. The flow of the oil is indicated by the dotted arrows.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )

4. Fig 3
Superimposed kinematic data at the ankle, knee, and hip joint of subjects A and B. (A) Wearing the AFO with the oil damper and (B) wearing the AFO with a plantarflexion stop. When subjects wore the AFO with the oil damper, there was an increase in ankle plantarflexion (1) and a decrease in knee maximum flexion at initial contact (2) and during late stance (3). There was no hyperextension of the knee during midstance phase (4) or remarkable plantarflexion of the ankle during swing phase (5), and hip maximum flexion (6) was increased in subject A and was decreased in subject B.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )