Prosthetic devices are provided to patients to not only replace a missing limb but also to help the patient achieve their mobility goals with the prosthesis. In the beginning, their mobility goals focus on stability, safe utilization, volume management, strength, coordination, and balance. As the user progresses, the prosthesis can be further customized to meet their unique functional goals and quality of life requirements. Below you'll find a description of different prosthetic types and designs incorporated in the treatment plan.
A preparatory prosthesis is an initial prosthesis intended for use in the patient's first stage of prosthetic rehabilitation for training purposes. Typically the preparatory prosthesis is used for 3 months to one year following amputation. After the preparatory phase, the patient will advance to using a permanent prosthesis and the preparatory prosthesis may be used in case of emergency.
It is medically necessary to provide the patient with the opportunity to train and rehabilitate with a preparatory prosthesis (in advance of a permanent prosthesis): (1) residual limb will undergo significant changes in volume, muscle tone, and soft tissue consistency, (2) patient requires time to recover, condition, and strengthen the body and retrain the body in ambulation, (3) prosthetist requires time and experience to fully assess the patient's activity level, functional needs, and ability to manage their prosthesis and associated componentry.
A permanent prosthesis is a definitive prosthesis intended for use after the training and rehabilitation phase, as the primary means of mobility for the next 3 to 5 years, depending on the exact circumstances. The permanent prosthesis is typically fit following successful usage and management of a preparatory prosthesis (exceptions apply). There are some cases where a patient will not be fit with a preparatory prosthesis in advance of a permanent prosthesis. Regardless, the permanent prosthesis is intended to enhance the patient's mobility and activity level and enable the patient to reach full functional potential.
It is medically necessary to provide the patient with a permanent prosthesis as a means for mobility and participation in activities of daily living, vocational tasks, and/or recreational activities. In most cases, the permanent prosthesis is fit after the initial prosthesis in response to the following: (1) residual limb volume has stabilized, muscle tone and soft tissue consistency have changed, and limb has matured, (2) patient has demonstrated ability to manage their prosthesis, (3) patient has identified functional needs based on experience, (4) patient has outperformed their training-level componentry, and (5) prosthetist has gained a full understanding of the patient's potential and can make informed decisions about the new prosthesis design and componentry. Additionally, a permanent prosthesis may be required at any time that the patient has demonstrated the need(s) for a new socket system and new componentry, including changes in their physiological condition and/or changes in their functional level and demands.
A replacement socket system consists of a replacement socket, including multiple design variations, and the corresponding interface and suspension system. It is medically necessary to provide the patient with a replacement socket system when the patient has undergone physiological changes, such as in body weight, residual limb volume and/or shape, or medical condition, and/or when the current prosthetic socket system is no longer providing appropriate safety/protection, comfort, and/or function. A socket system must allow for safe ambulation, adequately protect the residual limb from undue pressure, provide comfort to all contact areas of the limb, and function well. A well-functioning socket maintains stability in sagittal and coronal planes, maintains consistent suspension between limb and prosthesis, reacts harmoniously with the components, limits gait compensations, supports soft tissue, and limits skin irritation.
It is medically necessary to provide the patient with a replacement socket system when the patient has undergone physiological changes, such as in body weight, residual limb volume and/or shape, or medical condition, and/or when the current prosthetic socket system is no longer providing appropriate safety/protection, comfort, and/or function. A socket system must allow for safe ambulation, adequately protect the residual limb from undue pressure, provide comfort to all contact areas of the limb, and function well. A well-functioning socket maintains stability in sagittal and coronal planes, maintains consistent suspension between limb and prosthesis, reacts harmoniously with the components, limits gait compensations, supports soft tissue, and limits skin irritation.
Prosthetic Test Socket
A test socket is a diagnostic tool for establishing optimal prosthetic fit. Test sockets are fabricated from clear thermoplastic material, which offers visibility and adjustability. The socket can be seen through, facilitating an accurate assessment of total contact, tension values, pressure, anatomical contouring, and suspension. Additionally, thermoplastic is heat-moldable, allowing for minor adjustments to shape as needed also during an assessment.
It is medically necessary to provide the patient with up to two test sockets over the course of fitting for any new socket system. Test socket(s) are medically necessary to fully assess and adjust the fit and suspension of the socket, by way of the transparency and moldability of the material, prior to finalizing the socket design. Multiple test sockets are medically necessary because the residual limb undergoes volume changes during the prosthetic fitting process. A new socket system applies new pressures to the limb, which re-distributes fluid and thus changes limb volume and possibly its shape. When this occurs in the first test socket, a second test socket is necessary to accommodate for the changes and then reassess fit and suspension.
Flexible Socket, Rigid Frame
A prosthesis needs to enable the patient to regain mobility and resume everyday activities. For most amputees, this requires the ability to walk, or ambulate. Building strong ambulation skills requires motivation, practice, and expert gait training, typically provided in conjunction with a therapy program. As patients progress in their ability to ambulate (at increased speeds, over obstacles, across challenging terrain), adjustments to the prosthesis will become necessary in order to maintain comfort, function, and mobility. This development process requires adherence to the recommended training program and follow-up schedule.
It is medically necessary to provide a flexible inner socket/rigid frame to increase the comfort and protection of the skin and underlying soft tissues throughout the socket and especially at the proximal brim. A flexible inner socket also allows for an increased range of motion at the knee joint as the rigid frame may be safely lowered to increase brim flexibility yet maintain rigidity of the overall system. This design is also necessary to provide maximal adjustability of socket fit, which will likely be needed over the lifetime of the socket. For example, a flexible inner may be molded and/or frame may be fenestrated to provide localized relief over bony prominences; additionally, the two-layer system enables multiple volume management solutions.
Ischial containment is a feature of transfemoral or hip disarticulation socket design in which the proximal brim of the socket encompasses the patient's medial pelvis, namely the ischial tuberosity and ischio-pubic ramus. “Narrow ML” is another feature of transfemoral socket design that describes the relative narrowing of the ML dimension in the socket or increased pressure intentionally placed medially and laterally in the socket.
Ischial containment is medically necessary to compensate for the loss of natural control and stability of the hip and thigh following a transfemoral amputation or hip disarticulation. For transfemoral amputation, containing the ischium and creating a narrow ML dimension restores the natural femoral adduction angle, which (1) maximizes the efficiency of the remaining thigh musculature and (2) promotes a narrow-based gait (versus abducted gait deviation). Without ischial containment, the femur will drift into abduction, which decreases the efficiency of the thigh muscles. For hip disarticulation, there is no femur and so the adduction angle of the proximal pylon can be set; ischial containment still serves to increase coronal plane hip stability by countering the lateral displacement of the socket. For both cases, a narrow base of support during ambulation is essential to bring the weight line medially enough to ensure coronal plane stability during single-limb stance on the prosthetic side. To maintain this coronal plane stability, pressure increases medially and by containing the ischium and narrowing the ML, this medial pressure is born primarily by the pelvis as opposed to soft tissues.
Suction suspension is a form of subatmospheric suspension in which a one-way expulsion valve functions with an airtight seal to create a subatmospheric socket environment that secures the entire limb in place. A suction socket is fabricated with an impermeable plastic interface or resin such that the internal environment of the socket can be completely sealed off to the outside. A suction socket also includes the one-way expulsion valve, through which air may flow out of the socket but not back in.
It is medically necessary to provide a suspension method for any new socket system. A suspension system secures the residual limb to the socket, which is fundamental to the function of a prosthesis. A suction socket is a medically necessary element that comprises a suction suspension system. The suction socket enables an airtight seal to be created between the limb and the socket to ensure a strong, consistent connection with the prosthesis. Suction suspension system is superior to alternative forms of suspension because it is relatively unaffected by the downward pull of gravity, which minimizes relative movements inside the socket. Minimizing relative movement conserves energy, provides increased proprioceptive feedback to the patient, decreases risk for pressure points, decreases the perception of prosthesis weight, increases rotational control, and increases comfort.
Locking system is a form of mechanical suspension in which a suspension locking mechanism (shuttle lock or lanyard lock ) functions with a locking gel liner to provide a single distal point of attachment between the limb and the socket. In either system, the locking gel liner is tethered to the base of the socket and is disengaged by a release button (shuttle/pin lock) or by detaching the lanyard.
It is medically necessary to provide a suspension method for any new socket system. A suspension system secures the residual limb to the socket, which is fundamental to the function of a prosthesis. Suspension locking mechanism is medically necessary to provide consistent suspension, independent of fluctuations in residual limb volume and with superior connection compared with earlier suspension systems like waist belt and fork strap, suprapatellar cuff, sleeve, joint and thigh corset and plug fit. Locking suspension is simple and reliable and is most appropriate for patients using a preparatory prosthesis and/or who have decreased cognition, hand strength/dexterity, or are unable to tolerate suction or a suspension sleeve. This suspension is medically necessary for patients that require reliable suspension with improved connection and a simple solution for daily limb volume adjustments.
An elevated vacuum system consists of a suction suspension system and a vacuum pump. In this system, the socket environment is maintained at subatmospheric pressure at all times because the vacuum pump continually draws air out. A vacuum pump may be mechanical or electronic in nature. Mechanical pumps may be a separate component or integrated into the prosthetic foot and draw air from the system via compression from the user bearing weight. Electronic pumps are separate components that use sensors to detect the air pressure in the socket and remove air automatically as needed to maintain a set level of vacuum.
A vacuum pump is a medically necessary component of any elevated vacuum system. An elevated vacuum system is medically necessary for the following purposes: managing volume, allowing prosthesis use during wound healing, decreasing forces exerted on the limb, and improving proprioception by way of reduced movement within the socket. Elevated vacuum is the only means of managing daily limb volume fluctuations that does not depend upon the patient's involvement. Volume management is medically necessary to protect the patient against socket discomfort, skin breakdown, infection, revision, decreased mobility, inability to bear full weight on the prosthesis, overuse of the sound side limb, and/or rejection of a prosthesis. Many patients struggle with more traditional volume management methods, resulting in many of the aforementioned problems. Elevated vacuum system, including a vacuum pump, is medically necessary to aid patients who struggle with volume management on their own.
An adjustable prosthetic socket providers the user flexibility and control of their prosthetic fit. Depending on the design, the may be able to add additional control/stability, improve donning capability, control rotation, or volumetrically alter the socket in order to match the size of the residual limb. This is achieved through a dial attached to a lacing system that tightens with removing the prosthesis.
An adjustable socket is medically necessary for patients that require donning/doffing assistance, fluctuate in volume, provide additional comfort and stability, or permit the user to micro-adjust the prosthesis quickly.
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