PURPOSE--One of the most effective configurations fora transhumeral prosthesis is the hybrid prosthesis, whichcombines a cable-actuated body-powered elbow and anelectric-powered prehension device. The effectiveness ofthis configuration is attributed to two principalcharacteristics. First, the cable linking the elbow to themovement of the physiological shoulder provides control ofthe elbow's position, speed, and acceleration as well asperception of those quantities through the shoulder'sproprioception. Second, the electric-powered prehensiondevice produces grip forces three to four times greater thanis possible with a cable-actuated split hook and allowsmaintenance of low forces for delicate handling withoutphysiological effort to sustain the gripping force.
As an alternative, we have proposed todevelop a lighter electric prehensor for use by adults. Byreducing the weight of the prehensor, we believe it will bepossible to fit the hybrid configuration to a broader rangeof persons with upper-limb amputations, especially personswith short transhumeral limbs, and without significantlycompromising their ability to position the prosthesis inspace.
This makes mimicking the correct motion with an artificial limb very difficult. In the prosthetic industry a trans-humeral prosthesis is often referred to as a "AE" or above the elbow prothesis.
This is a basic list of terms for your information, and we are happy to provide you with further clarification about these or other terms if you require it. AK - Above the knee – Trans Femoral Alignment - Position of a prosthetic socket in relation to foot and knee Amputation - Removal of all or part of a limb due to infection, injury, tumor, disease or trauma Amputee - A person who has had all or part of a limb removed/amputated or is born without a limb Amputation (Traumatic) - A spontaneous removal of a limb for example as a result of an accident Bilateral - Bi means both, meaning both sides BE - Below elbow - Trans Radial BK - Below the knee - Trans Tibia Carbon Fiber - Non-stretch carbon fabric used to reinforce lightweight composite resin structures, such as prosthetic components and socket Claudication - Pain in the limb upon exertion – due to circulatory insufficiency Congenital limb deficiency - When all or parts of limb/s do not develop normally in the womb or are missing CPO - Certified Prosthetist and Orthotist (also known as CO - CP - CPOT) Disarticulation - Limb is amputated through the joint Doffing - Taking the prosthesis off Donning - Putting the prosthesis on ECG - Electro-Cardiograph, recording of the electrical activity of the heart Edema - Swelling of the tissues (also spelled oedema) Endo - Inside (as in: Endoskeletal Prosthesis – one with internal supporting structures) Exo - Outside (as in: Exoskeletal Prosthesis – one with external rigid fiberglass structure) Gait training - Learning to walk with a prosthesis Interface - Inner surface of socket, or portion of prosthesis closest to the skin Liner - Soft socket rolled or pulled over the residual limb and used for protection, comfort and in some cases as a suspension device Lower extremity - Lower limb Occupational therapy - Training to maximize independence in daily life PPAM - Pneumatic Post Amputation Mobility Aid is an inflatable device (not a prosthesis) that is used by some physiotherapists as part of the rehabilitation programme prior to prosthetic rehabilitation Patella - Kneecap Peripheral vascular disease - Disease of the blood vessels from a variety of causes Phantom pain - Painful feeling in the part of the extremity that has been amputated Phantom sensation - Awareness of the amputated limb although not described as pain Phantom limb - Sensation of the presence of the limb that has been amputated Physical therapy - Therapeutic exercises in order to treat a disease or a disability Pistoning - When a liner stretches so that the stump elongates – or the vertical motion of a residual limb inside a prosthetic socket Prosthesis - A fabricated/artificial substitute for a body part that is missing Prostheses - More than one prosthesis (plural form) Prosthetist (Canadian Certified) - Someone who designs, fits and makes artificial limbs and who’s education and training and expertise is recognized and credentialed by the Canadian Board for Certification of Prosthetists and Orthotists Residual limb - The remaining part of the limb after amputation (the stump) Socket - The part of the prosthesis (artificial limb) that fits around the residual limb – and fits around the Liner or socket insert if one is used Socket insert - A soft form that is contoured to fit around the residual limb and fits inside the Socket to provide for some increased padding and comfort for the residual limb Suction socket - A socket on an artificial leg that excludes the entry of air and is held to the residual limb by the suction of negative pressure maintained within the socket Total contact - Total contact between the residual limb and socket at all points Transradial - Amputation below the elbow (Through the radius and ulna bones) Transfemoral (TF) - Amputation above the knee (Through the femur bone) Transmetasatal (TM) - Amputation through the metatarsal foot bones (Partial foot amputation) Transtibial (TT) - Amputation below the knee (Through the tibia and fibula bones) Transhumeral - Amputation above the elbow (Through the humerus bone) Upper extremity - Upper limb Vascular amputation - Amputation surgery performed as a result of impaired circulation of blood through the blood vessels of the limb.
PROGRESS--During the past year, we have been assessingthe outcomes of these fittings and now have a high degree ofconfidence in this approach. We are especially convinced ofthe utility of the all mechanical, cable-actuatedfour-function control system used on the dominant side atthe transhumeral and shoulder disarticulation levels. Inthis configuration, a mechanical elbow, a wrist rotationunit, a wrist flexion unit, and a voluntary-opening splithook prehension device are arranged so that a single controlcable can be used to position any one of the fourcomponents. The single control cable and associated harnessprovide close coupling of the user and the prosthesis. Bodymovements and forces are transferred directly to theprosthetic components and the response of thecomponents (their position, velocity, acceleration, andforces acting on them) are perceived through the intactproprioception of the user. We believe, with the support ofusers' comments, that the extension of the user'sphysiological proprioception via the control cable reducesthe mental effort required in positioning and using theprosthesis.
The rotator design is intended for use with eitherbody-powered or electric-powered elbows. It can beaccommodated in prostheses for short transhumeral orhigher-level amputations and can be used unilaterally orbilaterally.
Myoelectric prostheses are well accepted by persons withtransradial amputations but less accepted by those withhigher level ones. The primary limitation at present lies inthe control system. Although these systems have beensuccessful for single device control (hand or elbow), theextension to the control of more than one device (eithersimultaneously or sequentially) has been difficult. It isthe control systems that now limits the performance and, attimes, the acceptance of the prosthetic fitting. For theperson with transhumeral or higher amputation and especiallyfor those with bilateral amputations, the need for improvedcontrol systems for multifunction prostheses is critical.