Updated: 10/10/2016

Rehab & Prosthetics

Topic
Review Topic
0
0
Questions
21
0
0
Evidence
25
0
0
Videos
4
https://upload.orthobullets.com/topic/9072/images/gait_patterns.jpg
https://upload.orthobullets.com/topic/9072/images/2_and_3_point.jpg
https://upload.orthobullets.com/topic/9072/images/bodypowered.jpg
https://upload.orthobullets.com/topic/9072/images/myoelectric.jpg
https://upload.orthobullets.com/topic/9072/images/myoelectric2.jpg
https://upload.orthobullets.com/topic/9072/images/bodypowered2.jpg
Gait
  • Antalgic gait describes any gait abnormality resulting from pain
    • antalgic gait associated with knee arthritis 
      • knee is maintained in flexion
      • shortened stride length
      • compensatory toe walking
  • Gait pattern of ambulation with an assistive device  
    • 3-point  
      • both the crutch and the injured limb move forward together with weightbearing on the crutches followed by all of the weight on the uninjured limb 
    • 4-point
    • swing-to
    • swing-through
  • Crutch walking
    • requires more energy than walking with a prosthesis
    • muscles that need strengthening in preparation for crutch walking
      • latissimus dorsi
      • triceps and biceps
      • quads
      • hip extensors
      • hip abductors
  • Wheelchair propulsion
    • 9% increase in energy expenditure compared to ambulation in normal subjects
  • Ambulation assistive devices
    • cane
    • axillary crutch
      • 2 axillary crutches are required for proper gait if lower extremity is non-weightbearing or toe-touch weightbearing  
  • Patient specific factors need to be considered when identifying the correct prosthesis for a patient
  • Low demand patients may not require a prosthesis for activities of daily living
  • Pearls for prosthetic gait abnormalities     
Upper Extremity Prosthesis
  •  Timing of prosthetic fitting
    • as soon as possible, even before wound healing has completed
      • transradial prosthesis outcomes depend on timing of fitting
        • 70% to 85% when fitted within 30 days of amputation
        • <30% when fitted later than 30 days of amputation
  • Myoelectric prostheses 
    • transmits electrical activity to surface electrodes on residual limb muscles
    • types of units
      • 2-site/2-function device
        • separate electrodes for flexion and extension
      • 1-site/2-function device
        • one electrode for flexion and extension
      • indications
        • best candidate is a patient with a transradial amputation 
        • best for sedentary work
        • can be used for overhead activities
    • advantages
      • better cosmesis
      • allows more proximal coverage
    • disadvantages
      • heavier and more expensive prosthesis
      • less sensory feedback
      • requires more maintenance
  • Body-powered prostheses 
    • indications
      • best for heavy labor with less maintenance needed
    • techniques
      • activate terminal device with shoulder flexion and abduction
      • center the harness ring just off the midline of C7 towards the non-amputated side  
    • advantages
      • moderate cost and weight
      • most durable prosthesis
      • higher sensory feedback
    • disadvatnages
      • poorer cosmesis
      • requires more gross upper limb movement for proper function
  • Components
    • Terminal device
      • passive terminal device
        • more cosmetic but less functional than active terminal devices
      • active terminal device
        • more functional, but less cosmetic than passive terminal devices
        • either hooks and prosthetic hands with cables or myoelectric devices
      • grips
        • precision grip (pincer-type)
        • tripod grip (palmar grip, 3-jaw chuck pinch)
        • lateral pinch (key pinch)
        • hook power grip 
        • spherical grip
      • prehension devices
        • handlike device
          • thumb, index, and long finger components
          • may be covered with a glove for better cosmesis
          • good choice for office worker
        • non-hand prehension device
          • hook or two-finger pincer with parallel surfaces
          • may attach task-specific tools with quick release mechanism
          • good for physical labor
        • myoelectric devices
          • can only be used in an environment clean from dirt, dust, water, grease, or solvents
      • mechanisms
        • voluntary opening
          • device is closed at rest and opens with contraction of proximal muscles
          • more common than voluntary closing
        • voluntary closing
          • device is open at rest and residual forearm flexors grip the desired object
          • heavier and less durable than voluntary opening
    • wrist units
      • quick disconnect wrist
        • allows easy swapping of devices with specialized function
      • locking wrist unit
        • prevents rotation during grasping and lifting
      • wrist flexion unit
        • used in bilateral upper extremity amputees
        • placed on longer residual limb to allow midline activities (shaving, buttoning)
    • elbow units
      • rigid elbow hinge
        • indications
          • short trans-radial amputation with inability to pronate or supinate with maintenance of elbow flexion
      • flexible elbow hinge
        • indications
          • wrist disarticulation or long transradial amputation with sufficient pronation, supination, and elbow flexion and extension
    • shoulder units
      • due to increased energy expenditure and weight of prosthesis many choose to use a purely cosmetic prosthesis
      • indications
        • forequarter or shoulder level amputation
Knee Prosthesis
  • Knee prostheses provide controlled knee motion
  • Indications
    • transfemoral and knee disarticulation amputations
  • Technique
    • the prosthesis needs to be in line with the weightbearing axis of the patient's knee
    • errors in technique
      • slightly posterior knee center of rotation allows better control of stance phase with more difficult flexion
      • slightly anterior knee center of rotation flexion is easier with less control
  • Socket
    • the connection between the stump and the prosthesis
    • protects the stump and transmits forces
    • preparatory socket may need to be adjusted several time as edema resolves
    • patellar tendon-bearing prosthesis is most common
  • Suspension systems
    • attaches prosthesis to residual limb using belts, wedges, straps, and suction
    • suction suspension
      • standard suction
        • form-fitting rigid or semi-rigid socket which fits onto residual limb
      • silicon suction
        • silicon-based sock fits over the stump and is then inserted into the socket
        • silicon provides an airtight seal between prosthesis and amputated stump
  • Knee joint
    • polycentric (four-bar linkage) knee 
      • indications
        • transfemoral amputation
        • knee disarticulations
        • bilateral amputations
      • techniques
        • variable knee center of rotation
        • controlled flexion
        • ability to walk at a moderately fast pace
        • supports increased weight compared to constant friction knee
    • stance-phase control (weight-activated) knee
      • indications
        • older patients with proximal amputations
        • patients walking on uneven terrain
      • techniques
        • acts like a constant-friction knee in swing phase
        • weightbearing through the prosthesis locks up through the high-friction housing
    • fluid-control (hydraulic and pneumatic) knee
      • indications
        • active patients willing to sacrifice a heavier prosthesis for more utility and variability
      • techniques
        • allows for variable cadence via a piston mechanism
        • prevents excess flexion
        • extends earlier in the gait cycle
    • constant friction (single axis) knee 
      • indications
        • general use
        • patients walking on uneven terrain
        • most common pediatric prosthesis
        • not recommended for older or weaker patients
      • technique
        • hinge that uses a screw or rubber pad to apply friction to the knee to decrease knee swing
        • only allows a single speed of walking
        • relies on alignment for stance phase stability
    • variable-friction (cadence control)
      • technique
        • multiple friction pads increase knee flexion resistance as the knee extends
        • variable walking speeds are allowed
        • not very durable
    • manual locking knee
      • technique
        • constant friction knee hinge with an extension lock
        • extension lock can be unlocked to allow knee to act like a constant-friction knee
  • Pylon
    • simple tube or shell that attaches the socket to the terminal device
    • newer styles allow axial rotation and absorb, store, and release energy
    • exoskeleton
      • soft foam contoured to match other limb with hard outer shell
    • endoskeleton
      • internal metal frame with cosmetic soft covering
  • Terminal device
    • Most commonly a foot, but may take other forms
Foot Prosthesis
  •  Single axis foot
    • ankle hinge allows dorsiflexion and plantar flexion
    • disadvantages
      • poor durability
      • poor cosmesis
  • SACH (solid ankle cushioned heel) foot 
    • indications
      • general use in patients with low activity levels
      • use is being phased out
    • disadvantages
      • overloads the nonamputated foot
  • Dynamic response (energy-storing) foot 
    • indications
      • general use for most normal activities
      • patients who regularly ambulate over uneven surfaces likely benefit from multi-axial articulated protheses 
    • articulating and non-articulating dynamic-response foot prostheses are available
      • articulating
        • allows inversion, eversion, and rotation of the foot
        • indications
          • patients walking on uneven surfaces
        • advantages
          • allows inversion, eversion, and foot rotation
          • absorbs loads and decreases shear forces
          • flexible keels
            • acts as a spring to decrease contralateral loading, allow dorsiflexion, and provide a spring-like push-off
            • posterior projection from keel gives a smooth transition from heel-strike
            • sagittal split allows for inversion and eversion
      • non-articulating
        • have short or long keels
          • shorter keels are not as responsive and are indicated for moderate-activitiy patients
          • longer keels are indicated for high-demand patients
        • different feet for running and lower-demand activities available
Prosthetic Complications
  • General issues
    • choke syndrome
      • caused by obstructed venous outflow due to a socket that is too snug
      • acute phase
        • red, indurated skin with orange-peel appearance
      • chronic phase
        • hemosiderin deposits and venous stasis ulcers
    • skin problems
      • contact dermatitis
        • most commonly caused by liner, socks, and suspension mechanism
        • treatment
          • remove the offending item with symptomatic treatment
      • cysts and excess sweating
        • signs of excess shear forces and improperly fitted components
      • scar
        • massage and lubricate the scar for a well-healed incision
    • painful residual limb
      • possible causes include heterotopic ossification, bony prominences, poorly fitting prostheses, neuroma formation, and insufficient soft tissue coverage
  • Transtibial prostheses   
    • swing-phase pistoning
      • ineffective suspension system
    • stance-phase pistoning
      • poor socket fit
      • stump volume changes (stump sock may need to be changed)
    • foot alignment abnormalities
      • inset foot
        • varus strain, circumduction and pain
      • outset foot
        • valgus strain, broad-based gait and pain
      • anterior foot placement
        • stable increased knee extension with patellar pain
      • posterior foot placement
        • unstable increased knee flexion
      • dorsiflexed foot
        • increased patellar pressure
      • plantar-flexed foot
        • drop-off and increased patellar pressure
    • pain or redness related to pressure
    • prosthetic foot abnormalities
      • heel is too soft
        • leads to excessive knee extension
      • heel is too hard
        • leads to excessive knee flexion and lateral rotation of toes
 

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Questions (21)

(OBQ06.12) A 27-year-old patient comes in for a new prescription for his below knee amputation prosthesis because it is not fitting properly. All of the following are complaints and examination findings consistent with a prosthetic foot that is placed too far inset EXCEPT: Review Topic

QID: 23
1

Varus strain

3%

(57/1778)

2

Socket pain located medial and proximal

19%

(339/1778)

3

Increased knee extension during stance

35%

(625/1778)

4

Socket pain located lateral and distal

34%

(604/1778)

5

Circumducted gait

8%

(137/1778)

ML 4

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(OBQ08.146) Which of the following amputations has the LEAST increase in metabolic demand for walking compared to a healthy patient without amputation? Review Topic

QID: 532
1

Traumatic transtibial amputation

79%

(1814/2290)

2

Vascular transtibial amputation

17%

(397/2290)

3

Vascular thru-knee amputation

1%

(24/2290)

4

Traumatic transfemoral amputation

1%

(13/2290)

5

Vascular transfemoral amputation

1%

(29/2290)

ML 2

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PREFERRED RESPONSE 1
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(OBQ08.266) A 45-year-old patient with a below knee amputation is interested in hiking as a hobby. He would like to know more about his SACH foot before selecting a different terminal device. A SACH foot or non-dynamic response (non-energy storing) foot, as compared to the dynamic response foot (energy storing) demonstrates all of the the following EXCEPT: Review Topic

QID: 652
1

Less frequent replacement

13%

(134/1011)

2

Less dorsiflexion

8%

(83/1011)

3

Longer duration midstance of gait

39%

(399/1011)

4

Increased ground reaction forces to the contralateral limb

28%

(287/1011)

5

Diminished maximal gait velocity

10%

(97/1011)

ML 4

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(OBQ10.245) A prosthetic polycentric knee with hydraulic swing control is chosen for a very active 63-year-old transfemoral amputee. All of the following appropriately describe the features of this prosthesis EXCEPT: Review Topic

QID: 3344
1

Flexes in a controlled manner

4%

(95/2472)

2

Variable cadence

8%

(197/2472)

3

Ability to walk at a moderately fast pace

4%

(107/2472)

4

Knee center of rotation is fixed anterior to the line of weight bearing

70%

(1735/2472)

5

Weighs more than a constant friction knee that has a manual extension locking mechanism

13%

(317/2472)

ML 2

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(OBQ06.254) A 44-year-old male with transtibial amputation is interested in doing more hiking as a hobby, however he has had difficulty negotiating uneven terrain with a solid-ankle, cushioned-heel (SACH) prosthetic foot. Which of the following modifications to the new prosthesis is most appropriate? Review Topic

QID: 265
1

Single axis foot

1%

(10/1100)

2

Shortened keel articulated dynamic-response foot

18%

(196/1100)

3

Lengthened keel articulated dynamic-response foot

12%

(133/1100)

4

Sagittal split keel articulated dynamic-response foot

64%

(699/1100)

5

Rigid keel nonarticulated dynamic-response foot

4%

(49/1100)

ML 3

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PREFERRED RESPONSE 4

(OBQ10.195) Patients with transradial amputations are considered the best candidates for a myoelectric prosthesis. Each of the following are advantages of a myoelectric device compared to a body controlled device EXCEPT: Review Topic

QID: 3287
1

Provide more proximal function

20%

(550/2776)

2

Better cosmesis

10%

(290/2776)

3

More sensory feedback

56%

(1555/2776)

4

Can be used in any position including overhead activities

8%

(224/2776)

5

Require less gross limb movement

5%

(137/2776)

ML 4

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PREFERRED RESPONSE 3

(OBQ09.267) In consideration of a prosthetic knee, each of the following are advantages of choosing a polycentric knee with fluid control over a constant friction knee EXCEPT: Review Topic

QID: 3080
1

Allows variations in cadence

4%

(49/1133)

2

Flexes in a more controlled manner

9%

(101/1133)

3

Lighter in weight

65%

(736/1133)

4

Improved stance control allows less energy expenditure

11%

(119/1133)

5

Overall length of the limb is shortened during initiation of a step reducing the risk of stumbling

10%

(117/1133)

ML 2

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PREFERRED RESPONSE 3

(OBQ06.101) A 35-year-old woman with a transtibial prosthesis is seen to have knee buckling (i.e "drop-off") during terminal stance. What prosthetic modification would correct this problem?





Review Topic

QID: 287
1

Dorsiflex prosthetic foot

6%

(104/1695)

2

Move foot more posterior

24%

(399/1695)

3

Increase flexibility/softness of keel

2%

(37/1695)

4

Move toe break of prosthesis more posterior

5%

(84/1695)

5

Move foot more anterior

62%

(1050/1695)

ML 3

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PREFERRED RESPONSE 5

(OBQ11.174) A 34-year-old female undergoes open reduction and internal fixation (ORIF) for the left lower extremity injury shown in Figures A-C. Her postoperative weight bearing protocol includes touch down weight bearing to the left lower extremity. Which of the following ambulatory support devices is most appropriate for this patient? Review Topic

QID: 3597
FIGURES:
1

Double axillary crutch

93%

(2147/2305)

2

Single forearm (Lofstrand) crutch

2%

(39/2305)

3

Single axillary crutch

3%

(76/2305)

4

Double cane

1%

(13/2305)

5

Single platform crutch

1%

(19/2305)

ML 1

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PREFERRED RESPONSE 1

(OBQ05.243) A prosthetic foot which incorporates a multi-axis articulated foot assembly is recommended for which of the following amputees? Review Topic

QID: 1129
1

Low functioning diabetic who needs to transfer bed to chair

0%

(0/990)

2

Long distance runner with below knee amputation

9%

(88/990)

3

Elderly male with above knee amputation

1%

(9/990)

4

Below knee amputee who needs to regularly walk on uneven ground

87%

(863/990)

5

10-year-old male with above knee amputation from osteosarcoma

2%

(23/990)

ML 1

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(OBQ11.177) A 32-year-old man has difficulty walking 5 months after having an amputation as shown in Figure A. Gait analysis reveals a shortened stance phase and irregular toe off on the operative extremity. Which of the following would most likely improve his ambulation? Review Topic

QID: 3600
FIGURES:
1

Solid ankle ankle-foot orthosis

7%

(196/2865)

2

Hip-knee-ankle-foot orthoses

1%

(24/2865)

3

University of California Biomechanics Laboratory (UCBL) insert

4%

(110/2865)

4

Full-length steel shank shoe modification

9%

(269/2865)

5

Full-length steel shank and rocker sole shoe modification

78%

(2244/2865)

ML 2

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PREFERRED RESPONSE 5

(OBQ11.41) The pattern of ambulation shown with the assistive device in Video A is most appropriately described as which of the following? Review Topic

QID: 3464
FIGURES:
1

Swing-to gait

55%

(1192/2151)

2

Drag-to-gait

1%

(24/2151)

3

Swing-through gait

32%

(684/2151)

4

3-point gait

5%

(110/2151)

5

4-point gait

6%

(121/2151)

ML 4

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PREFERRED RESPONSE 1

(OBQ10.145) A 34-year-old male is an inpatient at a rehabilitation hospital after sustaining severe lower extremity injuries in a motor vehicle collision. As a result, his energy expenditure while ambulating is 40% above baseline after being fitted with an appropriate prosthetic prescription. What is this patient's most likely lower extremity amputation level? Review Topic

QID: 3233
1

Unilateral long transtibial

3%

(80/2703)

2

Unilateral average transtibial

24%

(650/2703)

3

Bilateral transtibial

50%

(1342/2703)

4

Unilateral transfemoral

22%

(587/2703)

5

Bilateral transfemoral

1%

(31/2703)

ML 4

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PREFERRED RESPONSE 3

(OBQ04.209) What is the most important factor when choosing an optimal lower limb prosthesis for an adult patient? Review Topic

QID: 1314
1

Prosthesis cost

0%

(4/1650)

2

Patient comorbidities

1%

(16/1650)

3

Patient functional status

94%

(1549/1650)

4

Patient gender

4%

(65/1650)

5

Patient age

1%

(12/1650)

ML 1

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PREFERRED RESPONSE 3

(OBQ11.229) Which of the following is an example of an antalgic gait pattern not typically seen in clinical practice? Review Topic

QID: 3652
1

Patient's knee is maintained in slight flexion throughout the stance period for ipsilateral knee arthritis

6%

(79/1401)

2

Patient's contralateral step length is shortened with ipsilateral ankle arthritis

11%

(154/1401)

3

Patient leans their trunk laterally over the painful leg during stance phase with ipsilateral hip arthritis

17%

(244/1401)

4

Patient ambulates on their toes with an ipsilateral calcaneal stress fracture

4%

(56/1401)

5

Patient ambulates predominately through the heel for ipsilateral knee arthritis

61%

(859/1401)

ML 4

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PREFERRED RESPONSE 5

(OBQ10.128) All of the following are advantages of a body-controlled prosthesis compared to a myoelectric prosthesis for patients with upper extremity amputations EXCEPT: Review Topic

QID: 3221
1

Better for heavy labor activities

8%

(211/2730)

2

Decreased amount of harnessing

69%

(1893/2730)

3

Decreased amount of therapy for training

10%

(263/2730)

4

Lighter weight

10%

(273/2730)

5

Less prosthetic maintenance

3%

(73/2730)

ML 2

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PREFERRED RESPONSE 2
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