Soket
Soket berfungsi sebagai antarmuka antara sisa dahan dan prosthesis. Seharusnya tidak hanya melindungi sisa sayap tetapi juga harus dengan tepat mengirimkan pasukan yang berkaitan dengan berdiri dan ambulation. Persiapan yang (sementara) soket akan perlu disesuaikan beberapa kali sebagai volume yang sisa sayap stabilizes. Socket persiapan yang dapat dibuat dengan menggunakan plaster cetakan dari sisa sayap sebagai template. Berhubung dgn bagian badan buatan beberapa manufaktur menggunakan fasilitas komputer-teknologi untuk membantu memetakan sisa dahan, manufaktur stopkontak langsung dari data.
Yang paling umum digunakan dalam socket transtibial pemotongan adalah patellar otot kedang-bearing (PTB) soket. Soket ini menekankan peningkatan kontak atau berat peluru di daerah yang patellar urat daging, rendah ke lutut, tetapi tidak mengatakan bahwa terdapat kontak atau tidak signifikan berat peluru di tempat lain di sisa sayap. Konsep dari total kontak penting karena sebelum total PTB socket-kontak, transtibial sockets sering mengalami buka-berakhir, plug-sesuai desain, yang mengakibatkan berbagai masalah kulit, kesedakan sindrom kronis, koreng, dan masalah lain. Total-permukaan tanah (TSB) transtibial socket desain yang bergerak untuk konsep menekankan patellar urat daging bearing berat, tetapi juga memuat selektif ini membutuhkan bantuan lebih selektif dan beberapa wilayah di sisa dahan . Baik soket akan bekerja dengan baik untuk setiap amputee. prosthetist yang masih perlu untuk bekerja dengan individu yang sesuai untuk pasien yang memenuhi rongga itu kebutuhan pasien.
Dengan desain PTB, berat didistribusikan melalui berbagai daerah, seperti compartments anterior dan posterior dan di tengah-tengah tibial tajam. Satu Mei melihat istilah "total kontak soket", yang menunjukkan PTB desain. PTB soket yang memiliki variasi, termasuk PTB-supracondylar (PTB-SC) soket dan PTB-suprapatellar-supracondylar (PTB-SCSP) soket. J-PTB SC yang tinggi di tengah-tengah dan lateral sidewalls yang di atas dan memperpanjang melalui yg berhubung dgn tulang paha condyles, memberikan peningkatan stabilitas dan mediolateral diri untuk penskorsan prosthesis. The PTB-SCSP socket furthers yang PTB-konsep oleh SC juga memperluas aspek anterior sehingga lutut adalah ditutupi dalam soket. The PTB-SCSP socket memberikan tambahan kekejuran ke dinding dan mediolateral berlaku memaksa proximal ke lutut selama sikap, dengan cara memberikan umpan balik ke indrawi batas lutut recurvatum. The PTB-SC dan PTB-SCSP sockets yang digunakan terutama untuk amputees singkat dengan sisa limbah dalam rangka untuk meningkatkan varus / valgus kontrol dan memberikan permukaan area yang lebih besar untuk distribusi berat.
Pilihan lainnya adalah bersama-dan-pembatasan sistem yang sangat baik untuk digunakan kuat. Sistem ini dapat digunakan untuk meningkatkan berat permukaan tanah ke daerah paha atau ke luar mengambil transtibial sisa dahan, mentransfer berat ke paha. Joint-dan-pembatasan sistem juga digunakan ketika ada kebutuhan untuk menyediakan mediolateral besar bagi stabilitas lutut yang transtibial amputee (lihat gambar di bawah dan gambar 2). Pilihan lain adalah dengan bingkai kaku yang fleksibel liner; luar yang kaku bingkai jendela yang telah memberikan bantuan tambahan tekanan.
Alternatif desain untuk socket transtibial amputees adalah TSB socket yang digunakan dengan sistem elastomeric liner. TSB socket yang dibuat dari cast dari sisa anggota yang sedikit modifikasi. Bila digunakan dengan gel liners, yang diyakini TSB socket untuk mendistribusikan tekanan lebih seragam dalam soket. Harus dipelihara diingat bahwa gel liners sendiri memiliki kumpulan masalah, termasuk gerakan dan meningkat, khususnya, berputar ketidakstabilan yang membawa iritasi kulit dan kerusakan. yang relatif kelebihan dan kekurangan dari TSB versus PTB socket socket yang unik untuk masing-masing. Bila nyaman cocok dengan satu gaya soket tidak dapat dicapai, empirically beralih ke yang lain mungkin akan berhasil.
Yang paling sering yg siap untuk dimakan socket untuk transfemoral amputations adalah ischial pengurungan socket. Terdapat beberapa variasi halus dalam desain soket ini. Soket memiliki lebar anteroposterior dimensi dan dimensi yang sempit mediolateral. Rancangan ini menggantikan soket desain berbentuk persegi, yang memiliki dimensi lebar mediolateral dan dimensi anteroposterior sempit (lihat gambar di bawah ini dan Gambar 10). The ischial pengurungan socket awalnya dirancang untuk memberikan compression of soft tissues and limited abduction of the femur within the socket during the stance phase. It has been subsequently been demonstrated that resecuring the transected adductor muscles distally is more important and effective in controlling the lateral movement of the femur in the socket, resulting in improved prosthetic ambulation
Left, above-knee prosthesis with a quadrilateral socket, a hip joint and pelvic band suspension, endoskeletal components with a cosmetic foam cover and hose, a single-axis knee, and an energy-storing foot (close-up of the socket and the suspension system)
The suspension mechanism
Every prosthesis requires some type of suspension system to keep it from falling off the residual limb. Suspension can be achieved by a variety methods, including the following:
* Self-suspension of the socket - This makes use of the anatomic shape of the residual limb (Syme or knee disarticulation).
* Suction suspension - Methods of creating suction suspension include the use of an appropriate suction socket design, of a gel suspension liner.
* Suspension device or harness - Such equipment includes belts, cuffs, wedges, straps, and sleeves.
A combination of these techniques also can be used.
Standard suction is a common suspension choice for transfemoral prostheses; it employs a total-contact, form-fitting, rigid or semirigid socket with a 1-way air valve in the distal end that allows air to be expelled after the socket is donned. The socket's intimate fit creates a seal between the skin of the residual limb and the socket. When air is driven out of the end of the socket, a small negative pressure—strong enough to suspend the socket on the residual limb—develops inside the socket. This form of suspension allows excellent proprioceptive feedback and is lightweight. One disadvantage of the suction socket is its inability to tolerate much weight or volume fluctuation up or down before it requires replacement.
A total elastic suspension (TES) belt and a Silesian belt are used for auxiliary above-knee suspension or as the sole means of suspension, especially in the pediatric patient
Left, above-knee prosthesis with an ischial containment socket, a total elastic suspension (TES) belt, a single-axis knee with extension assist, endoskeletal components, and an energy-storing foot (lateral view with flexed knee).}}
The Silesian belt fastens to the socket laterally, above the greater trochanter, and wraps around the opposite iliac crest. Because it does not control rotation very well, people using this type of suspension belt often have difficulty with internal rotation, especially if the residual limb is fleshy. The TES belt is made from the same neoprene material that is used for transtibial suspension sleeves. It slips over the outside of the prosthetic socket and surrounds the waist above the iliac crest to provide suspension. The TES belt is more commonly used today than is the Silesian belt and aids in rotational control. Disadvantages include some inevitable pistoning of the prosthesis, reduced comfort because of bandage pressure, heat intolerance, and the possibility that the belt will cause dermatitis and chafing. A single-axis hip joint is integrated into the lateral socket wall and pelvic band to control rotation and is used for weak hip adductors or short residual limb
Auxiliary suspension options for patient with a transtibial amputation.
Auxiliary suspension options for patient with a transtibial amputation.
Another transtibial suspension option is suction. As with standard transfemoral suction suspension, it uses an airtight sleeve and a 1-way air valve located in the bottom of the socket to create a partial vacuum within the socket. This vacuum helps suspend the prosthesis during swing phase. The vacuum needed to hold the residual limb can be generated when air is expelled from the socket through the valve during stance, with a resultant negative pressure inside the socket during swing. The vacuum can also be generated through the use of a small vacuum pump built into the prosthesis. This vacuum-assisted suspension system (VASS) works by use of a vertical shock pylon that acts as a vacuum pump and continually withdraws air from the sealed socket during ambulation.
Knee joint
The prosthetic knee must fill the following 3 functions:
* Provide support during the stance phase of ambulation
* Produce smooth control during the swing phase
* Maintain unrestricted motion for sitting and kneeling
The prosthetic knee can have a single axis with a simple hinge and a single pivot point, or it may have a polycentric axis with multiple centers of rotation.
* The 4-bar linkage design and shifting center of rotation provide knee stability. Cosmesis is excellent, especially during sitting; therefore, this design is used for knee disarticulations and short residual limbs.
* Polycentric knees are heavy, costly, and require high maintenance.
* The weight-activated, or safety, knee cannot be flexed during weight bearing, which provides stability during stance phase. The safety knee can accommodate up to 20ยบ of knee flexion, produces friction, and prevents buckling. It allows ambulation on uneven surfaces. A delay in swing phase is noted because complete unloading of the knee must occur for knee flexion to transpire. The safety knee is a common initial prosthetic knee for geriatric patients, persons with extreme debility, and patients with poor hip control. It is contraindicated in patients with bilateral transfemoral amputations.
* The hydraulic knee (pneumatic or oil) allows for cadence variance. The design uses a piston in a fluid-filled cylinder that accommodates the swing phase of the patient's gait. The knee is heavy, costly, and requires high maintenance.
* The manual-locking knee provides the most stability, but the gait is awkward and energy consuming. However, it is ideal for a hemiparetic residual limb.
Prosthetic science is advancing the types of knees now available.
The hydraulic-based Otto Bock C-Leg (Otto Bock Health Care, Minneapolis, Minn) provides several benefits over purely mechanical knee systems. These microprocessor-controlled knees improve upon the timing of the hydraulic and pneumatic knees. The patient can ambulate at greater speeds with optimal, biomechanically correct symmetry while expending less energy. Most importantly, the user can safely walk step over step up and down stairs. The built-in battery lasts anywhere from 25-40 hours, which means that it can support a full day of activity. The recharge can be performed overnight or while traveling in a car (via a cigarette lighter adapter).
The magnetorheological-fluid–based Rheo Knee (Ossur, Reykjavic, Iceland; Ossur North America, Aliso Viejo, Calif) is capable of "learning" how the patient walks. Electronic sensors on the artificial joint measure the joint's angle and the loads it is bearing, 1,000 times per second while a computer chip controls the viscosity of magnetic fluid inside the knee. Tiny metal particles suspended in the fluid form small chains when the magnetic field is turned on, causing the fluid to become thicker. That, in turn, affects the stiffness of the joint, which is modified constantly while the knee is in use, allowing for a smooth swing of the leg. However, the cost of technologically advanced knees is prohibitory for most amputees.
Types of Prosthetic Knees and Usage
Type of knee
Advantages
Disadvantages
Possible usage
Single-axis, constant friction
* Simple
* Durable
* Low-maintenance
* Only constant swing phase control
* No stance control
* Single cadence*
* Excellent for pediatrics
* Useful for patients who have single cadence but good voluntary control of swing and stance phase
Polycentric without fluid control
* Has varying stability through stance
* Shortens shank during swing for better toe clearance
* Natural and better cosmetic appearance while sitting
* Increased weight and bulk
* Complex mechanism
* Single cadence
* Knee disarticulations
* Long transfemoral (for appearance)
* Short transfemoral (for knee stability)
* Weak hip extensors
Weight- activated stance control
* Benefits patients who do not have adequate control to manage a bending knee or good enough hip control to stabilize
* Braking mechanism if weight applied with knee flexed 0-20 degrees
* Helpful to slower candidates
* Requires regular maintenance
* Not very responsive for active walker
* Gait modified to unload knee
* Single cadence
* Geriatric patients
* Short residual limb
* General debility
* Uneven surfaces
Manual lock
* Total stability in stance phase
* No swing phase flexion, resulting in stiff knee gait
* Awkward in sitting
* Patient requires mechanical stability in stance
* Last resort
Fluid Control Units
Single-axis, pneumatic control
* Responds to changing gait speeds
* Higher cost
* May need more maintenance
* Heavy, but lighter than hydraulic units
* Gases are compressible and may not provide adequate resistance during vigorous activities
* Allow less precision in cadence control than do hydraulic units
* From pediatric patients to adults with good control
Single-axis, hydraulic control
* Swing responds to changing gait speeds
* In addition to cadence variation, some units can provide hydraulic stance stability to resist knee flexion during weight bearing
* May need more maintenance
* Heavier
* Hydraulic performance affected by extreme cold weather
* From pediatric patients to adults with good control
* Excellent reliability
* Good for the more active amputee
Polycentric and multiaxis, fluid control
* Varying stability through stance
* Shortens shank during swing for better toe clearance
* Smoothest gait
* Can unlock with some activities (biking)
* Natural and better cosmetic appearance while sitting
* Variable cadence
The pylon and ankle
The pylon is a simple tube or shell that attaches the socket to the terminal device. Pylons have progressed from simple, static shells to dynamic devices that allow axial rotation and that absorb, store, and release energy. The pylon can be an exoskeleton (soft foam contoured to match the other limb and covered with a hard, laminated shell) or an endoskeleton (an internal, metal frame with cosmetic soft covering). The ankle function usually is incorporated into the terminal device. A separate ankle joint can be beneficial in heavy-duty industrial work or in sports such as mountain climbing, swimming, and rowing. However, the additional weight of a separate joint requires more energy expenditure and greater limb strength to control the additional motion.
Prosthetic feet
The 5 basic functions of the prosthetic foot are as follows:
* Provide a stable, weight-bearing surface
* Absorb shock
* Replace lost muscle function
* Replicate the anatomic joint
* Restore cosmetic appearance
Prosthetic feet are broadly classified as energy-returning feet or non–energy-returning feet.
Non–energy-returning feet include the solid-ankle, cushioned-heel (SACH) foot and the single-axis foot (see images below and Images 5, 6, and 7 ). The SACH foot mimics ankle plantar flexion, which allows for a smooth gait. The prosthetic is a low-cost, low-maintenance foot for a sedentary patient who has had a BKA or an AKA. The rigid forefoot provides an anterior lever arm and proprioception. The single-axis foot adds passive plantar flexion and dorsiflexion, which increase stability during the stance phase. They are most commonly used for patients with a transfemoral amputation if knee stability is desired.
* Higher cost
* May need more maintenance
* Heavier
* Knee disarticulations
* Long transfemoral (for appearance)
* Short transfemoral (for knee stability)
* For patients who vary cadence frequency
Microprocessor Control
Single axis or multiaxis
* On board microprocessor, hydraulics, pneumatics, and servomotors to adjust knee for variable gait cycles
* Energy saving
* Highest cost
* Heavy Berat
* Unproven track record for dependability
* For active patients
* For patients who vary cadence frequency
* Allows more natural movement during stair descent
* Some computerized knees use a computer-regulated valve to adjust the swing phase resistance of a pneumatic cylinder
* Some use the computer to control swing phase function and stance phase stability
* Some systems use multiple sensors to send messages about changes in the patient's walk to the microchip 50 times per second
Below-knee, endoskeletal prosthesis with a supracondylar cuff suspension, a patellar tendon–bearing socket with a Pelite liner, and a solid-ankle, cushioned-heel (SACH) foot
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