Above-Knee Amputation - Disarticulation at the Hip
Hip Disarticulation Specialist Tony van der Waarde | Award Prosthetics
Above-Knee Amputation - Disarticulation at the Hip ..
Many materials are suitable for socket fabrication. As is the case with other levels of lower-limb amputation, the most commonly utilized socket material is a rigid thermosetting resin: polyester or acrylic. An increasing trend toward more flexible thermoplastic materials is evident, as in other aspects of prosthetic practice. One of the authors (J.W.M.) has fitted more than two dozen polypropylene/polyethylene copolymer sockets for hip-level amputation over the past decade with good long-term results in durability, comfort, and patient acceptance (Fig 21B-14.).
Torque-absorbing devices are often added to hip dis-articulation/transpelvic prostheses to reduce the shear forces transmitted to the patient and components. Ideally, they are located just beneath the knee mechanism (Fig 21B-9.). This increases durability by placing the torque unit away from the sagittal stresses of the ankle while avoiding the risk of introducing swing-phase whips (which can occur if it is placed proximal to the knee axis). The major justification for such a component is that the high-level amputee has lost all physiologic joints and, hence, has no way to compensate for the normal rotation of ambulation.
What does "Disarticulation" Mean? (with pictures) - …
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.
Prosthetic fitting is typically limited to motivated and physiologically vigorous individuals; still, a significant number do not become long-term wearers. To investigate this further, the senior author (T.v.d.W) studied a group of 20 male and female hip disarticulation and transpelvic amputees who were representative of the age and diagnoses typically encountered. Only 15% had been full-time users of their initial prostheses; many complained of how cumbersome or uncomfortable their rigid sockets seemed.
Hip Disarticulation or Hemipelvectomy - …
Another hip joint option is the Otto Bock four-bar knee disarticulation joint mounted in reverse as proposed by Peter Tuil of The Netherlands (Fig 21B-6.). Benefits claimed are parallel to those expected from a polycentric knee unit: increased ground clearance during swing phase due to the inherent "shortening" of the linkage in flexion and enhanced stability at heel strike amputees comment favorably on the smooth deceleration and good appearance while sitting that this joint offers.
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.
What is a Hemipelvectomy? (with pictures) - wiseGEEK
Hip Disarticulation Amputations Flashcards | Quizlet
This presentation help to know the development of hip disarticulation prosthesis in developing P&O field.
Prosthesis for Hip-Disarticulation Amputation - VidInfo
20/11/2017 · A hip disarticulation involves total removal of ..
Hip Disarticulation and Hemi-Pelvectomy - [PDF …
Development of hip disarticulation prostheses using a simulator based on neuro-musculo-skeletal human walking model
EBS -PRO- Knee, for Hip Disarticulation;
The traditional device prior to 1954 consisted of a molded leather socket with a laterally placed locking hip joint called a tilting-table prosthesis. Often shoulder straps were required for suspension. Gross pelvic thrust was required to propel the prosthesis, and a vaulting gait was common.
September 2014 - Hip Disarticulation
This is now the standard for prosthetic fitting worldwide, and locking joints are very rarely necessary. A molded plastic socket encloses the ischial tuberosity for weight bearing, extends over the crest of the ilium to provide suspension during swing phase, and affords excellent mediolateral trunk stability by fully encasing the contralateral pelvis. The prosthetic hip joint is attached to the socket anteriorly, and this results in excellent stance-phase stability plus good swing-phase flexion.
Life and Limb: Hip Disarticulation
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.
Prothesis for hip disarticulation
Although the anatomic differences between hip disarticulation and transpelvic (hemipelvectomy) amputations are considerable, prosthetic component selection and alignment for both levels are quite similar. The major differences are in socket design and will therefore be discussed in some detail. A full surgical report identifying muscle reattachments along with postoperative radiographs can be extremely valuable during the initial examination of the amputation site, particularly if any portions of the pelvis have been excised. This information, combined with a thorough physical examination and a precise plaster impression, will influence the ultimate fit and function of the prosthesis.
Descending Stairs with a Hip Disarticulation Prosthesis
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.
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