Transfemoral & Knee Disarticulate
AK Custom Shaped Cover and Flexible Protective Outer Surface Covering System
Custom Shaped Cover
A custom shaped cover is made of flexible foam that is attached to the outside of a definitive prosthesis and then shaped to resemble the sound side limb as closely as possible.
Flexible Protective Outer Surface Covering System
A flexible protective outer surface covering protects the prosthesis from excessive wear and adds cosmesis (makes it more attractive). This “skin” is applied to the foam once the patient receives a definitive prosthesis and the custom shaped cover is complete.
AK Thermoplastic Preparatory Prosthesis
The thermoplastic preparatory prosthesis is most often prescribed for transfemoral (above the knee) amputees. It is a temporary prosthesis used by active patients until the residual limb has healed well enough to be molded for a permanent prosthesis. Usually the patient’s limb is measured and molded while he/she is in the hospital, and the prosthesis is fit within 48 hours. This prosthesis has an adjustable socket to accommodate changes in volume in the residual limb, a manual locking knee, and a single axis or SACH foot. The prosthesis is held in place with a TES belt.
Dynamic Response Foot
The dynamic response foot provides energy storage and return for active amputees (K3, K4). This foot is often prescribed for active amputees who walk greater distances or run.
Hip Joint with Pelvic Band and Belt Suspension
The hip joint with pelvic band and belt suspension is used with transfemoral (above knee) prostheses. This style of suspension provides rotational control and mediolateral (side to side) stability of the pelvis (hips). It works best for patients who are obese or for those who have a large amount of redundant tissue that is difficult to stabilize. This suspension can also be effective for patients who have weak abductor muscles.
The hydraulic knee is a single axis prosthetic knee in which the flexion and extension of the shin section of the prosthetic leg are controlled by a fluid-filled cylinder to offer the patient cadence control (this allows the patient to walk at a self-selected walking speed).
Ischial Containment Socket
The ischial containment socket is designed for transfemoral (above knee) amputees. The weight bearing is primarily on the ischium and the ischial ramus. This socket design contains the ischial tuberosity and ramus to create a boney lock for mediolateral (side to side) stability. This socket can be held in place on the residual limb by suction, a Silesian or TES belt, or by the use of a soft insert with a suspension locking mechanism. In comparison to the quadrilateral socket, this design better accommodates fleshy limbs and high activity patients.
The knee disarticulation procedure is a surgical procedure in which the tibia and fibula (shin bones) are separated from the femur (thigh bone). Then the lower leg and foot are removed from the body. No bones are cut in this procedure, which usually allows the patient to bear some weight on the end of the femur (thigh bone).
Manual Locking Knee
A manual locking knee is the most stable prosthetic knee because it automatically locks when it is extended. This type of knee requires more energy expenditure and is not cosmetic because the amputee must walk with a stiff knee. The knee is unlocked for sitting by a lever on the prosthesis. This type of prosthetic knee is recommended for patients with very little or no muscular control of the residual limb. However, it can also be used by patients engaged in activities that require greater stability, such as standing in a boat.
The MAS socket design is used by transfemoral (above knee) amputees. The socket contains the ischio-ramal complex and excludes the gluteal (buttocks) muscles. This socket can be held in place on the residual limb by suction, a Silesian or TES belt, or by the use of a soft insert with a suspension locking mechanism. Because of the design, this socket is the most cosmetic (best looking) and allows for the greatest mobility in comparison to the quadrilateral and ischial containment sockets. However, the fitting of a MAS socket design is extremely time-consuming. It is not uncommon for the fitting process to involve 3-5 check socket fittings, which is several more than conventional prosthetic sockets typically require. This style of socket is recommended for very active patients with stable residual limb volume.
Microprocessor controlled knees offer constant adjustment of the prosthetic knee mechanism during the entire gait cycle. Force sensors in the pylon detect loading of the foot and ankle and additional sensors read the precise angle of the knee joint. This data, along with swing speed input, is read 50 times per second by the on-board microprocessor. The result is increased stability, ease of swing, and greater efficiency with every step. As the range of walking speed and activity increases, the knee adapts appropriately, optimizing cadence response for individuals while they progress to higher levels of function.
Multi Axis Foot
The multi axis foot provides inversion, eversion and rotation at the ankle of the prosthesis. This type of foot is typically prescribed for active prosthetic patients (K3, K4) who need to traverse uneven surfaces.
The pneumatic knee is a single axis knee in which flexion and extension of the shin section of the prosthetic leg are controlled by an air-filled cylinder to offer the patient cadence control (this allows the patient to walk at a self-selected walking speed).
The polycentric knee is designed to have more than one axis of rotation to better simulate the anatomy of the human knee. This type of knee has greater mechanical stability than the single axis knee. Its design creates varying stability throughout the gait cycle, creating greater mechanical stability at heel strike and less stability at toe-off to ease the transition to swing phase. Because of the design, the shank of the prosthesis shortens as the knee bends, allowing better cosmesis (appearance) during ambulation (walking) and while seated.
The quadrilateral socket is designed for transfemoral (above knee) amputees. The weight bearing in this socket is primarily on the ischium and the gluteal musculature (buttocks). This combination of bone and muscle rests on the posterior brim (back edge) of the socket which creates a wide seat parallel to the ground. This socket can be held in place on the residual limb with suction, a Silesian or TES belt, or by the use of a soft insert with a suspension locking mechanism. This design aids in ease of sitting and, in comparison to the ischial containment socket, is more successful on long, firm residual limbs.
The SACH foot is typically provided to amputees who most often walk at single speeds and on even surfaces (K1, K2). This foot is also used for new amputees while they are learning to use a prosthesis. It provides stability and a smooth transition from heel to toe during a normal gait cycle.
Silesian Belt Suspension
A Silesian belt can be made of leather, cotton webbing, or nylon webbing. This belt is used to suspend a transfemoral (above knee) prosthesis on the patient’s body. The belt is worn around the patient’s waist, above the iliac crest (hip bone), and attaches to the lateral (outside) and anterior (front) surfaces of the prosthesis.
Single Axis Foot
The single axis prosthetic foot has a movable ankle joint. This joint allows the patient to reach foot flat quickly, thus increasing stability. This foot is often prescribed for above knee amputees and patients who require greater stability (K1, K2).
Single Axis Knee
The single axis knee is a simple hinge mechanism. The stability is dependent on the alignment of the prosthesis and the amputee’s muscular control. This knee can be used in conjunction with an extension assist to help the amputee reach full extension of the prosthetic knee before initiating weight bearing on the prosthesis.
Suction and Semi-Suction Suspension
Suction and semi-suction socket designs can be used in both transfemoral (above knee) and transtibial (below knee) prostheses. In this case, an expulsion valve is installed in the bottom of the prosthetic socket. As the patient dons (puts on) the prosthesis, air escapes through the valve creating negative pressure, or suction, on the residual limb. This type of suspension requires that the patient maintains consistent limb volume and that his/her socket fits precisely.
Suspension Locking Mechanism: Lanyard Strap for Lower Extremity
Suspension locking mechanism is a term used to describe the way the prosthesis will be attached to the patient’s residual limb. The two most commonly used types of suspension locking mechanism are the attachment pin and lock body, and the lanyard strap. The lanyard strap method is often used with transfemoral (above knee) prostheses. The lanyard is attached to the distal (bottom) end of a silicone or urethane insert. As the patient dons (puts on) the prosthesis, the lanyard is fed through a hole in the bottom of the prosthetic socket, through a buckle on the anterior (front) surface, and secured in place with Velcro.
TES Belt Suspension
The TES belt is an elastic sleeve and belt combination used with transfemoral (above knee) prostheses. The sleeve is placed around the prosthetic socket and the belt is wrapped around the patient’s waist to keep the prosthesis on the body.
The transfemoral (above knee) amputation is a surgical procedure in which a portion of the femur (thigh bone) is cut and removed from the body along with the lower leg and foot.
Transfemoral Immediate Post-Operative Dressing
The transfemoral immediate post-operative dressing is a semi-rigid dressing applied in the operating room following a transfemoral amputation (above the knee). The incision is dressed by the surgical staff and then mild compression socks are applied to the limb. The dressing is made of plastizote (perforated foam) and held in place with a waist belt. This dressing is usually left in place for 2-4 days to protect the limb and control edema (swelling).
Transfemoral Rigid Removable Dressing
The transfemoral (above knee) rigid removable dressing is usually applied to an amputated limb 2-4 days after surgery. The incision line is covered with non-stick gauze and then mild compression socks are applied to the limb. The rigid removable dressing is placed over the socks and secured to the patient’s body with a belted compression sock. The rigid removable dressing can be made of thermoplastic (white plastic) or fiberglass. This dressing will protect the amputated limb and control edema (swelling).
Weight Activated Stance Control Knee
The weight activated stance control knee has a weight activated braking system to prevent the knee from buckling under the amputee. This type of knee is often prescribed for patients with little muscular control.