|
Year |
2002 |
|---|---|
|
Question Number |
164. |
|
Category |
Rehabilitation |
Question
What type of prosthetic knee is considered most appropriate for a 65 year old man with a knee disarticulation?
1- Constant friction
2- Variable friction
3- Weight activated
4- Polycentric
5- Fluid control
Figures
Answer (click for answer)
Preferred response: (4) Polycentric.
Six basic types of prosthetic knees are available: constant friction, variable friction (cadence control), stance phase control (weight-activated or safety), polycentric (four-bar linkage), manual locking, and fluid control (hydraulic and pneumatic). A polycentric knee has a moving instant center of rotation that provides for different stability characteristics during the gait cycle and may allow increased flexion for sitting. It is recommended for patients with trans-femoral amputations, patients with knee disarticulations, and bilateral amputees.
Knee disarticulation is a muscle balanced amputation level that can be used in patients with diabetes, peripheral vascular disease, and trauma. Patients who are capable of sitting in a chair retain an excellent platform for sitting, a lever arm for transfer, and are unlikely to have joint contractures develop. In patients who are ambulatory and have vascular disease and in patients with trauma, this amputation level provides a well padded residual limb that allows distal end-bearing. The use of a polycentric (four bar linkage) prosthetic knee joint confers intrinsic knee joint stability during walking.
Reference: Koval KJ (ed): OKU Update 7. Rosemont, IL AAOS 2002; 139-48.
Pinzur MS, Bowker JH: Knee disarticulation. Clin Orthop 1999:361:23-8.
Gottschalk F. Rehabilitation: gait, amputations, prosthetics, orthotics. In Miller review of orthopedics, 3rd ed. 2000; 442-459.