Upper Limb Prostheses PDF

Upper limb prostheses Types Upper Limb Prostheses Cosmetic Functional Body Externally Hybrid powered powered Myoelectric Switch control Cosmetic prostheses They are usually constructed...

Upper limb prostheses Types Upper Limb Prostheses Cosmetic Functional Body Externally Hybrid powered powered Myoelectric Switch control Cosmetic prostheses They are usually constructed of light weight plastics, and are designed to match the color and shape of the patients intact hand. Disadvantages More difficult to keep clean Usually expensive Sacrifice some function for the increase the cosmetic appearance. Functional prostheses  I.Body power prostheses:(cable controlled) The prosthetic is powered through the tension of a cable, where the tension is generated through the mechanical transmission of muscular effort generated elsewhere in the body, remote from the amputation site.  Components of body powered prothesis Terminal Cosmetic Control- Units Socket Suspension device gloves cable system Wrist Elbow Shoulder  Terminal device Active Passive (prehensor) Voluntary Functional Cosmetic opening voluntary Child mitt closing Ball handle Child mitt Ball handle Terminal devices: 1) Passive Has no moving part, cables or batteries for operation Eg: children's mittens 2) Active or Prehensors Offer active grasp, based on how they work: it can be classified into A. Voluntary-opening: At rest held closed by a spring or rubber band and opens when the control cable is pulled. B. Voluntary-closing : Devices operate in a converse manner. This type of mechanism usually is heavier and less durable than a voluntary opening mechanism.  Voluntary-closing Voluntary-opening prehensor terminal Hook terminal device device  2. Cosmetic gloves A rubberized covering that determines the external appearance of the prosthesis. Applied over the shell of a passive hand or over the mechanism of an active prehensor Can be replaced when it deteriorates from use  3) Units A. Wrist units Prosthetic wrist units have two basic functions: 1. Attach the terminal device to the forearm of the prosthesis 2. Permit pre-positioning of the terminal device before operation (to substitute supination and pronation). N.B Above elbow transhumeral amputee has lost all ability to supinate and pronate the prosthetic forearm. Transradial amputee with a short residual forearm no longer retains active transmissible supination and pronation.  Types 1. Friction wrist units Commercially available wrist units permit the amputee to substitute for supination and pronation by manually rotating the terminal devices with the remaining normal hand. 2. Quick change wrist unit Designed to facilitate rapid interchange of different terminal devices (usually a hook and hand). It permit the amputee to do the followings: Remove the terminal device from the wrist unit Replace the terminal device with different terminal device Manually position the terminal device in supination and pronation and lock the terminal device in supination or pronation. 3. Wrist flexion unit: →Provide wrist flexion →Requires pressing a button to allow moving the wrist joint It can provide an amputee, especially a bilateral upper limb amputee, with improved function for midline activities (shaving, manipulating buttons).It usually is employed on only one side, most often the longer of the two residual limbs.  4. Electric wrist Electric wrist rotator B. Elbow units Below elbow amputation *Flexible hinge: suitable for long below elbow amputation, allows transmission of the residual forearm supination and pronation to the terminal device. *Rigid hinge: in case of short below elbow or above elbow amputation, supination and pronation is no long available. It must be associated with rotatable wrist unit to allow positioning of the terminal device Above elbow amputation *Body-powered elbows, controlled by the same cable that operates the terminal device with an additional attachment or button that operates elbow lock. When elbow is unlocked, pulling on the cable will flex the elbow. When the elbow is locked or fully flexed, pulling on the cable will operate the Terminal device. *Electronic powered elbows: Elbow lock is operated electronically.  C. Shoulder units Bulkhead The simplest Allow no motion at the shoulder Passive shoulder Can be positioned passively Further classified into single axis units permit only abduction Double axis units allow abduction and flexion Sockets an important connection between the individual and prosthesis Enable optimum ROM of the remaining anatomic joints resist torques and forces that act to twist or move the prosthesis relative to the residual limb. Protect the skin of the residual limb The socket should also be a rigid platform for distal components, such as the forearm and terminal device. The socket should be designed to be able to distribute the pressure so that it doesn’t add overpressure to fragile tissues.  The primary interface between the residual limb and prosthetic socket is one of the following methods: Skin-fit The skin may contact the inside of the socket directly. This method offers the most direct control of the prosthetic limb Suitable for myoelectric prosthetics to receive electrical signals from the underlying muscles. The limitation is potentially exposing the skin to areas of high pressures and sheering forces. Prosthetic sock, socks provide an easy method to don the socket and provide some cushioning between the skin and the socket. However, this method requires additional means to suspend the socket, normally through the harness of a body-powered control system. Silicone liner. rolled onto the residual limb and inserted into the socket. Silicone liners may be prefabricated or custom-made for the individual and offer a superior way to protect the skin (especially for those with skin grafts or fragile skin)  4) Suspension Harnessed- Self-suspending Suction based systems sockets sockets A) Harnessed-based systems Transradial *Axillary loop: serves as the primary anchor from which two other straps originates. It encircles the shoulder girdle on the nonamputated side. *Anterior support strap: or inverted Y shape suspensor. It originates at the axilla loop passes over the shoulder on the amputated side and is attached to the anterio- proximal margins of the triceps pad of the prosthesis. which in turn supports the socket through the flexible elbow hinges The primary function of this strap is to resist displacement of the socket on the residual limb when the prosthesis is subjected to heavy loading. The control attachment strap: originates at the axilla loop and terminates at the proximal end of prosthetic control cable. it acts as an extension of the control cable. Its position is between the spine and the inferior angle of scapula; it permits the use of scapular abduction and shoulder flexion to operate the terminal device. The posterior junction of the axilla loop with the anterior support and the control attachment straps can be sewn together or connected by a stainless steel ring which is called O-ring is formed stainless steel which allow alternation of the length of strap. transhumeral Like the standard transradial harness, the transhumeral harness consists of →Axilla loop, →Anterior support strap, →Lateral support strap, →Control attachment strap →Elbow lock control strap 5-Control-cable system Cable is firmly attached at its proximal end to the straps of the harness. Distally, it terminates at the terminal device Control-cable system Transradial control system: a one-cable or "single- control" system which allow perhension movement and grasping. Transhumeral control system : operated by two distinctly separate cables. →One serves to flex the prosthetic elbow joint and to operate the terminal device. → A second cable permits locking and unlocking the prosthetic elbow.  Two cables systems Cable responsible for locking and unlocking elbow Cable responsible to flex elbow and Cable close terminal responsible to flex elbow and device close terminal device Cable responsible for locking and unlocking elbow In standard transradial harness the single cable originated proximally from the straps , and inserted distally in the terminal device, the patient use body movement to produce tension on the cable and allow movement of the terminal device: Common body movement 1: shoulder flexion for open the terminal device and back to neutral to the relaxed position closes the device.. 2: Scapular abduction →open terminal device , scapular adduction → close terminal device. In standard transhumeral harness: Dual cable movement: →One cable serves to flex the prosthetic elbow joint and operate the terminal device. →A second cable permits the amputee to lock and unlock the prosthetic elbow. The elbow flexion/terminal device control cable Originates at the control attachment strap of the harness. Passing through the proximal portion of the split housing, the control cable is anterior to the mechanical elbow axis so it flex the elbow joint The housing through which the elbow flexion/terminal device cable passes is split into two separate parts, The proximal portion of the split housing is attached to the posterior surface of the humeral section of the prosthesis (cross bar assembly). The distal portion of the split housing is fixed to the prosthetic forearm by a device called an “Elbow flexion attachment. The elbow flexion/terminal device control cable continues through the distal portion of the split housing and terminates with its attachment at the terminal device, The flexion is limited to the gap between the two cable housings. The ease with which the amputee can operate the elbow unit and terminal device depends on the location of the elbow flexion attachment. Greater force and less cable excursion are required when: The elbow flexion attachment is closest to the elbow axis. Conversely, A more distal placement of the attachment requires less force but greater cable excursion. 2) Elbow lock control cable: The proximal end of the elbow lock control cable originates at: →The anterior suspension strap, →Passing down the anteromedial surface of the humeral section of the prosthesis, →The distal end of the cable engages the elbow locking mechanism. The elbow lock works on an alternator principle: pull and release to lock, pull and release to unlock. B) self-suspending and suction sockets Capable of providing adequate prosthetic suspension without the use of a harness. However, either design can also be used with a harness suspension to provide for a more secure suspension of the prosthesis. Self-suspending sockets are largely limited to wrist or elbow disarticulations and to transradial amputations. Advantages and disadvantage of body power prostheses: Advantages: Durable and simple Positional and control awareness through proprioception. Can operate in wet, dirty or dusty environments. Low cost and light weight Disadvantages: Bad cosmetic due to exposed cable and hooks. It depend on the muscle effort. Harness may restrict the amputees work. Requirements for using body power prostheses →Muscle control of gross body movement: →Glenohumeral flexion →Scapular abduction or adduction →Shoulder depression and elevation →Chest expansion  II.Myoelectrically controlled prosthesis: Is an externally powered prosthesis that uses EMG signals from residual voluntary counteracted muscles in the limb. Electrode sensors are embedded in prosthetic socket make contact with the surface of the skin. Uses muscle contractions as a signal to activate the prosthesis. It detect electrical activity from selected residual limb muscles through a surface electrodes.  The 2-site/2-function (dual-site) system has separate electrodes for paired prosthetic activity, such as flexion/extension. This is more physiologic and easier to control. 1-site/2-function (single-site) when limited control sites (muscles) in a residual limb are available. This system uses 1 electrode to control both functions of a paired activity. The patient uses muscle contractions of different degrees to differentiate between flexion and extension. For instance, a strong contraction opens the device, and a weak contraction closes it. Switch-controlled, externally powered prostheses: Utilize small switches, rather than muscle signals, to operate the electric motors. Switches are enclosed inside the socket or incorporated into the suspension harness of the prosthesis. Switch can be activated by the movement of a digit or part of a bony prominence against the switch or by a pull on a suspension harness (similar to a movement a patient might make when operating a body-powered prosthesis). This can be a good option to provide control for external power when myoelectric control sites are not available or when the patient cannot master myoelectric control. Externally powered prostheses Advantages Disadvantages Electric motors may provide Heavy more proximal function. Expensive Greater grip strength Uses batteries and motors Improved cosmetics less sensory feedback Require more maintenance. Physical therapy management for Upper limb amputation  Rehabilitation program Goals: Residual limb shrinkage and shaping. Residual limb desensitization. Pain management Scar mobilization Maintain the normal ROM. Increase muscle strength. Maximize independence. Myoelectric site testing. Residual limb shrinking and shaping: Started once wounds are sufficiently healed and are able to tolerate increased shearing forces. Compression by bandaging in figure of 8 from distal to proximal. Decreasing the amount of compression as we progress proximally. Thus fluids will be moved proximally Reapplied every few hours Worn full-time except during bathing Intermittent positive pressure compression Below Elbow Above elbow  Gentle massage and tapping techniques. Residual limb desensitization: Vibration. Minimize the physical or psychological Constant touch. over responses to a stimulus. Input of various textures to the sensitive area Pain management Phantom sensation: sensations perceived as originating from the amputated limb. Phantom pain: sensations of pain perceived as originating from the amputated limb. Residual limb pain: pain in the part of the limb left after the amputation. Vibration therapy. Ultrasound. Analgesics. Mirror therapy. Virtual reality.  Mirror therapy. The use of a mirror box in which the uninvolved side is visually reflected as the missing side, has been shown to decrease phantom limb pain Scar Mobilization. This technique is done to keep the skin and scar tissue on your residual limb loose. Scar adherence to underlying tissue can be a source of pain when using your prosthesis It is best performed when you are not wearing your compression dressing.  Technique Place two fingers over a bony portion of your residual limb. Press firmly and, keeping your fingertips in the same place on the skin, move your fingers in a circular fashion across the bone for about 1 minute. Continue this procedure on all of the skin and underlying tissue around the bone of your residual limb.  Maintain the normal ROM and improve muscle strength Increase effective gross motor movements and appropriate mechanics. This helps reduce the use of compensation strategies that may lead to injuries. Normal scapular mobility and residual joint mobility should be restored Once ROM is addressed, overall strengthening, postural exercises, and cardiovascular endurance are introduced Treatment focuses on individual activation of the targeted muscles and progresses to motor control exercises. identify potential muscles which can be used to control electrodes that control the prosthesis.  Body symmetry postural awareness training begins with observation of static postures in front of a mirror progressed to dynamic postural awareness by incorporating the use of a mirror during therapeutic dynamic activities. performing exercises and tasks in front of a mirror and the therapist provides additional verbal and tactile cues as necessary. Isometric and isotonic strengthening exercises are initiated with the use of a mirror to provide visual feedback. Strengthening equipment is modified as necessary to allow the use of the residual limb. Scapular stabilization exercises and core strengthening are also introduced to support good posture. Myoelectric site testing and training Using myotester to pick the electric potential generated by the muscle. 1-Simulation and training product 2-Provides biofeedback  Maximize independence Change of the dominant hand in case of dominant side amputation Interventions are directed at increasing fine motor coordination, and reaction time, improving handwriting, and developing one-handed typing skills. Fine motor activities used according to the nature of the ADLs of the patient Teaching one-handed activities Ensuring independence with and without the prosthesis is an important component of overall function in variable situations throughout life. Training on one-handed keyboarding to facilitate success in computer operations.  Fitting A recommended wear schedule is three 30-minute sessions per day with advancement of 30 minutes each day. The residual limb should be examined after removal, and prosthetic wear should be discontinued should any redness persists for more than 20 minutes. The goal is to tolerate wearing a prosthesis for 8 to 10 hours daily for functional activities. The patient is educated on limb inspection and donning and doffing the prosthesis Next, the focus shifts to the accommodation of the weight of the prosthesis while standing and moving the extremities. Donning methods for transradial amputee a) The roll on silicon liner is inverted and rolled onto the residual limb. b) The residual limb is placed through the harness (note the locking pin at the distal end of the liner). c) The limb is guided into the socket with slight pressure to secure the pin into the pin lock within the socket. d) Instructing in the jacket method of donning, the harness is pulled across the back and the residual limb is placed through the remaining figure- of-eight harness. e) Instructing in the over the head method, the residual limb is placed through the figure-of-eight harness anteriorly before guiding the harness overhead. f) The completed figure-of-eight body-powered prosthetic system is donned. transhumeral amputee a. the elbow is locked into 90 degrees flexion and the prosthesis is laid out with the harness system toward the outside of the body. b. The residual limb is placed into the socket using downward force with the prosthesis stabilized using the remaining limb. c. The harness is donned across the back and under the residual arm. The harness is secured to the anterior portion of prosthesis with snaps, buckles, or Velcro (Velcro USA Inc, Manchester, NH).  Bilateral amputation donning Body Powered Myoelectric If each prosthesis has an independent harness system, Self-suspending sockets are often donned using a reduced the longer of the residual limbs is donned first. This friction donning sock. prosthesis is then used to assist with donning the second The patient will use the lower extremities or the other prosthesis. prosthesis to pull the sock through the pull tube that pulls the If the prostheses are connected by harnessing, the soft tissue into the socket providing an intimate fit with skin shorter residual limb prosthesis will be donned first. traction. The two most common methods of donning attached Suction sockets are donned using an evaporative moisture prostheses is to don the prostheses as you would a coat technique. or to place both limbs simultaneously in the prostheses Air is expelled through the valve as the limb is pushed into the and don them overhead like a T- shirt. socket creating a suction fit. If the prosthesis is donned using the jacket or T-shirt To doff a self-suspending type of prosthesis, patients will method, the prosthesis is doffed using the method in typically use their lower extremities or the environment to reverse. assist in removing the prosthesis. In the case of a suction suspension, patients will often use an object in their environment to assist them in pressing the button on the valve that will release the suction. The donning stand can also be used as needed Training After the patient becomes familiar with the weight of the prosthesis, the rehabilitation transitions to control and operation of the prosthetic limb. The tasks should be simple Training should include objects of various shapes, sizes, textures, densities, and weights. The focus of the training of the control should include joint positioning to place the prosthesis in the proper position The patient should be able to start to control the amount of force needed to accomplish a task The patient can be positioned in front of a mirror for increased body awareness during movement and learn to self-correct body asymmetry and awkward postures caused by the weight of the prosthesis. Second stage There is less focus on the repetition of basic functions and more emphasis on completing ADLs and valued functional activities. The patient is trained to incorporate the prosthesis as the assisting limb for a unilateral amputation. Third stage The patient should be encouraged to select personally meaningful tasks The patient should try various terminal devices and adaptive tools to decide what tools and techniques best meet his or her specific needs. Training tasks should be multistep and challenging. More complicated tasks depending on the nature of the work or sport Body control motions In all proximal levels of upper-limb loss, body-powered. →Elbow flexion is facilitated by a forearm lift assist that counterbalances the weight of the forearm. →Elbow extension is accomplished by gravity if the elbow unit is unlocked. →Elbow lock/unlock is perhaps one of the most difficult tasks to learn in the operation of a transhumeral prosthesis. The pattern of "down, back, and out" is often stated to the amputee in an effort for him to repeat the shoulder depression, extension, and abduction pattern. Thank you