Prosthetics And Orthotics Flashcards
Lowest center of gravity in gait cycle?
Loading phase
Highest center of gravity in gait cycle?
Midstance
Location of center of gravity during gait?
5cm anterior to S2 vertebra
Components of stance phase?
Initial contact (heel strike)
Loading response (foot flat)
Mid stance
Terminal stance (heel off)
Preswing (toe off)
Components of swing phase?
Initial swing (acceleration)
Mid swing
Terminal swing (deceleration)
Determinants of gait
Pelvic rotation
Pelvic tilt
Knee flexion (stance phase)
Foot mechanisms
Knee mechanisms
Lateral displacement of the pelvis
Cause of trendelenburg gait?
Weak hip abductors (glute med and min), loss of pelvic stabilization, hip drop in contra lateral side
Probable cause of foot slap?
Weak dorsiflexors (at most 3/5)
Probable cause of genu recurvatum?
Weak, short, or spastic quads; compensated hamstring weakness, Achilles tendon contracture, plantar flexor spasticity
Probable causes of excessive foot supination during gait?
Compensated forefoot valgus deformity
Pes cavus
Short limb
Probable causes of excessive trunk extension during gait?
Weak hip extensors or flexors
Hip pain
Decreased knee ROM
Probable causes of excessive trunk flexion during gait?
Weak gluteus maximus and quads
Hip flexion contractures
Probable causes of excessive knee flexion during pre-swing?
Hamstring/hip flexion contracture
Increased ankle dorsiflexion
Weak plantar flexion
Long limb
Probable causes of excessive trunk lateral flexion during loading?
Compensated trendelenburg gait: ipsilateral glute medius weakness, hip pain
Gait pathology: stooped posture, festinating (shuffling) gait, decreased arm swing, reduced trunk rotation
Parkinson’s Disease
Also characterized by start hesitation and freezing
Primary disturbance in Parkinson’s gait?
Reduced step length
Gait impairment seen in duschenne muscular dystrophy?
Toe walking - stance phase w/ plantar flexion to maintain a weight line posterior to the hip and anterior to extended knee to compensate for weak knee extensors or for increased lumbar lordosis (which itself is compensating for weak hip extensors)
Gait impairment seen w/ hip flexion contracture? Energy expenditure increase?
increased anterior pelvic tilt, decreased contralateral step length, increased knee flexion
Increase energy expenditure: a 35 degree contracture due to iliopsoas tightness results in 60% increase in energy consumption
Increased energy expenditure in wheelchair users with paraplegia?
9% increase
Energy expenditure for crutch walking?
Increased compared to walking with a prothesis
Muscles that need strengthening in preparation for crutch walking: latissimus dorsi, triceps, pectoralis major, quads, hip extensors, hip abductors
Increased energy expenditure for syme’s amputation?
15%
Increased energy expenditure for traumatic transtibial amputation?
25% (short tibia 40%; long tibia 10%)
Increased energy expenditure for traumatic b/l transtibial amputations
41%
Increased energy expenditure for traumatic transfemoral amputation
60-70%
Increased energy expenditure for traumatic b/l transfemoral amputations?
> 200%
Traumatic transfemoral and transtibial amputations?
118%
vascular transtibial BKA?
40%
Increased energy expenditure for vascular transtibial BKA?
40%
Increased energy expenditure for vascular transfemoral AKA?
100%
Increased energy expenditure for hip disarticulation?
100-200%
Risk factor for vascular amputation that contributes to 2/3 of all lower extremity amputations?
Diabetes (prevalence of PVD is 20% higher in diabetic population)
Leading cause of upper extremity amputation?
Trauma - 80% of UE amputations, majority of limited to digital amputations
When is amputation considered for mangled hand?
If irreparable damage occurs to four of the six basic parts: skin, vessels, skeleton, nerves, extensor, and flexor tendons.
Initial goal: save all feasible length
Most common upper extremity amputation?
trans-radial - allows for high level of functional recovery in majority of cases
Most common upper extremity terminal device?
Body-powered voluntary opening
Importance of wrist flexion unit in UE amputees?
allows terminal device to be in flexed position, facilitates ability to perform activities close to the body
Which socket designs work well for short residual upper extremity limbs?
Split socket - consists of total-contact segment encasing the residual limb that is connected by hinges to a separate forearm shell to which the wrist unit and terminal device are attached
Meunster socket (self-suspended socket); the socket and forearm are set in a position of initial flexion; socket encloses the olecranon and epicondyle of the humerus
Most commonly used harness suspension system for transradial amputations?
Figure 8 (O-ring) harness
Axilla loop, worn on intact side, acts as a reaction point for transmission of body force to the terminal device
Prosthesis for elbow disarticulation?
Variation of transhumeral prosthesis - socket is flat/broad distally to conform to epicondyles, which provides self-suspension and allows for internal/external rotation of the humerus. Length of the residual limb requires use of external elbow joint w/ cable-operated locking mechanism. Harness and control system = same as transhumeral prosthesis.
Harness design for the most frequently used transhumeral prostheses?
modifications of the basic figure-8 and chest strap patterns that are used with transradial prostheses
Muscle groups used for myoelectric control in below-elbow amputees?
Wrist extensors (ECRL/B & ECU) are used to open the terminal device
Wrist flexors (FCR & FCU) are used to close the terminal device
Muscle groups used for myoelectric control in above-elbow amputees?
Biceps - flex elbow and close terminal device
Triceps - extend elbow and open terminal device
*With short transhumeral or shoulder amputation, shoulder girdle muscles are used to control elbow function and terminal device function
Advantages and disadvantages of body-powered upper extremity prostheses?
Advantages: less expensive, lighter, more durable, easier to repair, higher sensory feedback
Disadvantages: mechanical appearance, difficult to use for some people, dependent on motor strength
Advantages and disadvantages of myoelectric upper extremity prostheses?
Advantages: better cosmesis, less harnessing, stronger grasp force
Disadvantages: more expensive, heavier, decreased durability due to electronic components and the need for daily recharging of batteries
Most common cause of upper limb amputation
Trauma (distal > proximal)
Most common cause of lower limb amputation?
Dysvascular disease (PVD, DMT2, factor V Leiden), distal > proximal due to compromised vasculature
Complications if a prosthesis socket wall does not remain in contact with all parts of the limb?
Venous choke points leads to skin breakdown, warts (verucus hyperplasia)
Exceptions can be made for window cutouts in areas of sensitive skin (bony overgrowth, neuroma, skin breakdown sites)
Most common congenital limb defect?
left transradial - the longer the residual limb, the more pronation/supination function remaining
Ideal residual limb shape for transfemoral amputation?
conical
Ideal residual limb shape for transtibial amputation?
cylindrical (optimal spot to amputate is within proximal 50% of tibia
What level is a Syme amputation?
everything below the tibia, calcaneal fat pad is placed below tibia, can bear weight (low-level ambulator)
Myoplasty vs. Myodesis
Myoplasty: muscles are sutured to each other (easier surgery)
Myodesis muscles are sutured to the bone - more stable surgical result (not suitable in severely dysvascular patients as this will not heal properly)
Which motions are most affected in upper extremity amputations?
Transhumeral amputations: 80% have limitations of numeral rotation
Transradial amputations: 80% have limitations in forearm rotation
Diagnostic criteria for peripheral artery disease/peripheral vascular disease
ABI (ratio of brachial systolic pressure to ankle systolic pressure)
0.91 - 1.30 Normal (> 1.30 may suggest calcified, non-compressible vessels - common in diabetes, can produce false negatives)
0.71 - 0.90 mild PVD
0.41 - 0.70 moderate PVD
0.00 to 0.40 severe PVD
*If ABI is abnormal, Doppler waveform localizes the lesion
*Itra-arterial contrast angiography is the gold standard imaging test for PVD (invasive, should not be used for screening)
Level of lisfranc amputation?
Tarsometatarsal junction
Level of Chopart amputation?
Removes all of the tarsals and metatarsals. Only the talus and calcaneus remain
What foot deformity is common in Lisfranc and Chopart amputations?
Remaining foot develops a equinovarus deformity resulting in excessive anterior weight bearing with breakdown. Adequate dorsiflexor tendon reattachment w/ Achilles tendon lengthening has been advocated for to prevent this deformity
