Symes amputations are excellent for traumatic injuries, diabetics, infections, and sarcomas. They have traditionally been shunned in vascular/ischemic situations because of poor healing rates (30%)
For below elbow amputations (trans-radial), the best length is through the distal 2/3 1/3 junction. Supination and pronation is progressively harder the shorter the stump is. A minimum of 6 cm is needed to put a prosthesis on and have it powered in space by the elbow. Short of this, pronation/supination decreases rapidly; when 60% or more of the forearm is lost, so is pronation/supination. Hence, it is like a one bone forearm and rotation is accomplished by the shoulder rotating.
In AKA prosthesis, the mechanical knee must lie posterior to the axis of the trochanter-ankle line so that in heel strike, the knee locks into extension; if it were to lie anterior, the knee would collapse into flexion on heel strike.
The AKA socket can be flexed slightly to put the extensors on stretch, thus increasing their efficiency
The pattern of weightbearing in an AKA socket proximally is medial, and distally is lateral
Myo-electric prosthesis are best suited for trans-radial amputees
Myo-electrics tend to be more comfortable than the harness, provide better pinch strength and are cosmetically better than the hook. They are heavy, and functionally may not be better (hand tasks are performed quicker with the hook), difficult in warm weather, require batteries, need maintenance, and are costly. They are preferred by most though to a hook and harness.
In a short stump below elbow amputee, they need a Munster socket that pulls over the supracondylar ridge for suspension
In BKA prosthesis, a supracondylar socket acts as the suspension device via its shape conforming to the condyles of the femur.
The most appropriate appliance for a LisFranc amputee is an AFO with shoe filler initially, then they may manage with a shoe filler alone. This level probably requires tendo-achilles lengthening, and varus may require tib ant transfer to the lateral aspect of the foot.
In elderly patients with AKA – they may not have the coordination to put on a suction sleeve suspension device – they’re probably better off with sylesian belt suspension, because this is easier to put on. Go with a safety knee on them, so they don’t fall.
The reason to preserve the knee and do a BK versus a knee disarticulation is to improve the gait and energy demands of walking. It is not end-bearing, but the benefits outweigh the risks. Geriatric patients may do better with an end-bearing stump though.
At present, transcutaneous O2 level of 20-30 mmHg is the best indicator of skin healing in amputations
Nutrition plays a role: albumin 3.5 gm/dl and total lymphocyte count of 1500
A BKA with knee instability and anterior distal stump pain: due probably to the stump socket being too flexed so that the anterior part of the socket pushed into his stump all the time.
A stump that shows bulbous edema needs to have the proximal socket expanded.
With respect to function of an AKA, the most important technical thing to do is to ensure that you do an adductor myodesis.
The Munster suspension for a short below elbow increases flexion at the elbow
Pronation and supination of a high above elbow is done passively with shoulder motion.
In a five year old with a short below elbow amputation, they need a Munster suspension device over the supracondylar ridge.
Distal overgrowth in a childhood amputation stump is due to terminal overgrowth, not proximal physeal growth.
A rigid dressing is good for all amputation stumps except for vascular stumps.
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