Whenever an adequate below-the-knee stump cannot be obtained, a knee disarticulation is the next procedure of choice. The operative procedure is quick, safe, and causes less shock than amputations through the thigh. The circulation in the thigh is preserved, to supply skin flaps which are accustomed to pressure.
Because muscle and bone are not transected, the spread of infection is minimised, and the stump heals rapidly. When the patellar tendon has been fixed distally, patellar pain and swelling have not been significant problems. The largest surface available in the lower extremity is provided for weight-bearing. The stump is firm and insensitive. There is less atrophy of the muscles in the stump than after amputations at a higher level and, because of this, earlier fitting of a prosthesis is possible. The shape of the stump provides greater balance and stability without rotation than that of stumps in higher amputations. The patient can walk with an excellent gait almost immediately.
The prosthesis for such stumps is easy to construct and to fit, requires fewer adjustments, and is superior to prostheses for higher levels of amputation through the thigh.
Without a prosthesis the patient can kneel in work or play, as weight bearing is possible on the end of the stump in much the same way as the Symes amputee can on his longer stump.
A Through knee amputation is also called a knee disarticulation amputation and is a fairly common amputation where the leg is amputated through the joint line of the knee. This enables you to weight bear on distal end of the femur as the bone isn’t cut during the surgery. This isn’t possible in Transfemoral and Transtibial amputations.
A Through knee prosthesis is challenging to use at first but with training independence from assistive devices such as crutches can be achieved after 4 to 12 weeks of receiving the prosthesis. Due the absence of a knee joint a prosthetic knee joint will be required.
A through knee socket is custom made according to the shape and size of the residual limb and this custom-made socket is the part of the prosthesis that interacts with your residual limb and the prosthetic components.
The prosthesis is suspended from the limb by means of a vacuum system, a silicone liner with a ring seal and one-way expulsion valve. It is usually not possible to use a pin lock system in this prosthesis as it will lower the centre of rotation of the knee. The centre of the knee joint isn’t symmetrical with the contralateral leg, this is due to the thickness of the liner, socket and the types of prosthetic knees available. Weight-bearing is distributed over the entire surface of the residual limb and the femoral condyles.
The prosthetic knee joint allows both flexion and extension and varies in function depending on which knee you and your prosthetist choose to use. Our prosthetists are experienced in using a wide range of knee joints and we are manufacturer certified to fit high-end componentry including the X3, Genium, C-leg and Rheo Knee joint.
A variety of feet can be used with this type of prosthesis and this will again be decided by you and your prosthetist.