Above-Knee Prosthetics – Hanger Clinic
Pioneering innovative above-knee prosthetic socket designs
Above Knee Prosthetics - Prosthetic Legs | MCOP Prosthetics
Under the direction of certified prosthetist Kevin Carroll, M.S., C.P., a nationwide team of lower extremity practitioners undergo extensive socket design training.The LEPP provides options for all levels of patients, including symes, below knee, above knee, hip disarticulation and hemi-pelvectomy ."The most important feature we offer the lower extremity patient is the patented Hanger Socket System.
In an effort to overcome this limitation, the hip flexion bias system was developed for the young, active amputee who wished to walk rapidly. At toe-off, kinetic energy from the coil spring is released, and the prosthetic thigh is thrust forward. Not only does this provide the amputee with a more normal-appearing gait, it also improves ground clearance. As a result, the prosthesis can be lengthened to a nearly level configuration in most cases (Fig 21B-5.). However, two potential problems have been noted with this approach. One is the development of annoying squeaks in the spring mechanisms after a few months of use, which sometimes tend to recur inexorably. A more significant concern is that as the spring compresses between heel strike and midstance, it creates a strong knee flexion moment. Unless this is resisted by a stance control knee with a friction brake or a polycentric knee with inherent stability, the patient may fall. Since the friction-brake mechanisms lose their effectiveness as the surface wears, the polycentric knee is the preferred component with this hip mechanism.
Recent Advances in Above-Knee Prosthetics ..
Other than the exception discussed above, knee mechanisms are selected by the same criteria as for transfemoral (above-knee) amputees. The single-axis (constant-friction) knee remains the most widely utilized due to its light weight, low cost, and excellent durability. Friction resistance is often eliminated to ensure that the knee reaches full extension as quickly as possible. A strong knee extension bias enhances this goal and offers the patient the most stable biomechanics possible with this mechanism. Although the single-axis type was proposed as the knee of choice for the Canadian hip disarticulation design, more sophisticated mechanisms have proved their value and are gradually becoming more common.
One of the inherent limitations of the Canadian design is that the prosthesis must be significantly short (1 cm+) to avoid forcing the amputee to vault for toe clearance. Fig 21B-3. and Fig 21B-4. illustrate why this is so. At toe-off, the heel rises up during knee flexion and pulls the hip joint firmly against its posterior (extension) stop. The thigh segment remains vertical until the knee has reversed its direction of motion and contacted the knee stop. Only then does the thigh segment rotate anteriorly and cause the hip joint to flex. In essence, the prosthesis is at its full length during midswing. Since the patient has no voluntary control over any of the passive mechanical joints, the prosthetist is forced to shorten the limb for ground clearance.
The articulated above-knee prosthesis functions as a compound ..
A third type that has proved advantageous for this level of amputation is the polycentric (four-bar) knee. Although slightly heavier than the previous two types, this component offers maximum stance-phase stability. Because the stability is inherent in the multilinkage design, it does not erode as the knee mechanism wears during use. In addition, all polycentric mechanisms tend to "shorten" during swing phase, thus adding slightly to the toe clearance at that time. Many of the endoskeletal designs feature a readily adjustable knee extension stop. This permits significant changes to the biomechanical stability of the prosthesis, even in the definitive limb. Because of the powerful stability, good durability, and realignment capabilities of the endoskeletal polycentric mechanisms, they are particularly well suited for the bilateral amputee. Patients with all levels of amputation, up to and including translumbar (hemicorporectomy), have successfully ambulated with these components.
For many years, the use of fluid-controlled knee mechanisms for high-level amputees was considered unwarranted since these individuals obviously walked at only one (slow) cadence. The development of hip flexion bias mechanisms and more propulsive foot designs have challenged this assumption. Furthermore, a more sophisticated understanding of the details of prosthetic locomotion has revealed an additional advantage of fluid control for the hip-level amputee.
Below-Knee Prosthetics – Hanger Clinic
A Hanger Clinic prosthetist is fitting a bilateral above-knee patient
Above Knee Prosthetics
OSSUR Above/Below Knee Titanium Prosthetic left ..
of the knee joint improves the amputee's prognosis for ambulation with a below-knee prosthesis.
Below Knee Prosthesis for Amputees 5.10.12 ..
amputation of Hanger's leg above the knee, ..
Bilateral Above Knee Prosthetics Training - VidInfo
Many authors have noted that the rejection rates for lower-limb prostheses are the highest at these proximal levels. The energy requirements to use such prostheses has been reported to be as much as 200% of normal ambulation. At the same time, the lack of muscle power at the hip, knee, and ankle/foot results in a fixed, slow cadence. As a practical matter, only those who develop sufficient balance to ambulate with a single cane (or without any external aids at all) are likely to wear such a prosthesis long-term. Those who remain dependent on dual canes or crutches for balance eventually realize that mobility with crutches and the remaining leg, without a prosthesis, is much faster and requires no more energy expenditure than using a prosthesis does.
Although these patients will wear an above-knee prosthesis with a ..
It is well accepted that any fluid-control mechanism (hydraulic or pneumatic) results in a smoother gait. Motion studies conducted at Northwestern University have confirmed that a more normal gait for the hip dis-articulation/transpelvic amputee is also produced. Gait analysis has demonstrated that utilization of a hydraulic knee in a hip disarticulation prosthesis results in a significantly more normal range of motion at the hip joint during the walking cycle than is possible with conventional knees. In addition, a more rapid cadence was also possible.
fitted above the knee with a prosthetic leg, ..
Finally, a number of new components have been developed recently that combine the characteristics of some of the above classes of knee mechanisms. For example, Teh Lin manufactures a "Graphlite" knee consisting of a polycentric unit with pneumatic swing-phase control in a carbon fiber receptacle. Such "hybrid" designs are expected to increase over the next few years.
Genium Knee Bionic Prosthetic System - Hanger Clinic …
One of the first great minds in surgery and prosthetic design was Ambroise Paré, whose many contributions include an above-knee contraption and a much more functional foot prosthesis.
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