Updated: 4/7/2020

Rehab & Prosthetics

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Questions
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Evidence
21 21
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Videos
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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
Introduction
  • The goal of prosthetics are to restore limb function to as close to original function
  • Requires a multidisciplinary team approach for coorindation of efforts to achieve the best outcome
  • Prosthetics
    • upper limb
      • limb salvage is ideal in the upper arm given lack of sensation with prosthetic
      • residual limb length is important for suspending prosthetic socket
    • lower limb
      • goals for prosthetic are comfort, easy to get on and off, light, durable, cosmetic, and functional
Gait
  • Antalgic gait describes any gait abnormality resulting from pain
    • shortened stance phase on the affected limb
  • Gait pattern of ambulation with an assistive device  
    • 3-point  
      • both the crutch and the injured limb move forward together with weight-bearing 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
      • shifts center of gravity towards affected side when cane is used on contralateral side
    • axillary crutch
      • 2 axillary crutches are required for proper gait if lower extremity is non weight-bearing or toe-touch weight-bearing  
Upper Extremity Prostheses  
  •  Timing of prosthetic fitting
    • as soon as possible, even before complete wound healing has completed
      • better outcomes if fitted within 30 days
  • Midlength transradial amputation 
    • Myoelectric prostheses 
      • best candidate is a patient with a midlength transradial amputation 
      • transmits electrical activity to surface electrodes on residual limb muscles
      • advantages
        • better cosmesis
        • allows more proximal coverage
      • disadvantages
        • heavier and more expensive prosthesis
        • 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
      • disadvantages
        • poorer cosmesis
        • requires more gross upper limb movement for proper function
  • Elbow disarticulation or above elbow amputation
    • requires a prosthesis to recreate functional motion of two joints (elbow and wrist)
      • this creates heavy and less efficient as the only solution
      • best function with least weight is achieved by combining the various options of myoelectric, body-powered, and body-driven switch components
  • Proximal transhumeral and shoulder disarticulation amputation
    • an amputation this proximal has lost the ability to create a lever arm with mechanical advantage
    • best option is a universal shoulder joint that is positioned in space with the contralateral arm
    • this can be combined with lightweight hybrid prosthetic components
  • 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
Lower Limb Prosthesis
  • Foot prosthesis
    • Single axis foot
      • ankle hinge allows dorsiflexion and plantar flexion
      • disadvantages
        • poor durability and 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 prostheses 
      • 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-activity patients
            • longer keels are indicated for high-demand patients
          • different feet for running and lower-demand activities available
    • Shanks
      • provide structural support between components
      • endoskeleton (soft exterior) or exoskeleton model (hard exterior)
      • can provide a lever arm for propulsion following transmetatarsal amputation 
  • Knee prosethesis
  • Indications
    • transfemoral and knee disarticulation amputations
    • patient functional status is an important consideration 
  • Six types of prostheses for AKA or through knee
    • 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
  • Socket
    • the connection between the stump and the prosthesis
    • computer screening technology can decrease time to socket fabrication  
    • preparatory socket may need to be adjusted several times as edema resolves
    • patellar tendon-bearing prosthesis is most common for BKA
    • transfermoral or quadilateral sockets make it hard to keep the femur in adduction
      • transfemoral allow 10 degrees of adduction and 5 degrees of flexion
  • 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
  • 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
  • Osseointegration 
    • direct attachment of a prosthesis to the skeleton
    • may improve biomechanical advantage of prosthesis and rehabiliation
  • Terminal device
    • Most commonly a foot, but may take other forms
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
        • drop-off or knee buckling can be improved by moving the foot more anterior 
      • 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 (14)

(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 | Tested Concept

QID: 3597
FIGURES:
1

Double axillary crutch

93%

(2513/2696)

2

Single forearm (Lofstrand) crutch

2%

(41/2696)

3

Single axillary crutch

3%

(90/2696)

4

Double cane

1%

(19/2696)

5

Single platform crutch

1%

(20/2696)

L 1 C

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 3600
FIGURES:
1

Solid ankle ankle-foot orthosis

7%

(229/3289)

2

Hip-knee-ankle-foot orthoses

1%

(25/3289)

3

University of California Biomechanics Laboratory (UCBL) insert

4%

(124/3289)

4

Full-length steel shank shoe modification

10%

(315/3289)

5

Full-length steel shank and rocker sole shoe modification

78%

(2566/3289)

L 2 C

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 3464
FIGURES:
1

Swing-to gait

55%

(1391/2533)

2

Drag-to-gait

1%

(36/2533)

3

Swing-through gait

32%

(806/2533)

4

3-point gait

5%

(133/2533)

5

4-point gait

6%

(145/2533)

L 4 C

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 3344
1

Flexes in a controlled manner

4%

(105/2785)

2

Variable cadence

8%

(224/2785)

3

Ability to walk at a moderately fast pace

5%

(132/2785)

4

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

69%

(1923/2785)

5

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

13%

(371/2785)

L 2 C

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 3287
1

Provide more proximal function

20%

(597/3003)

2

Better cosmesis

11%

(332/3003)

3

More sensory feedback

55%

(1641/3003)

4

Can be used in any position including overhead activities

8%

(253/3003)

5

Require less gross limb movement

5%

(158/3003)

L 4 C

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 3221
1

Better for heavy labor activities

8%

(240/3046)

2

Decreased amount of harnessing

68%

(2080/3046)

3

Decreased amount of therapy for training

10%

(304/3046)

4

Lighter weight

10%

(319/3046)

5

Less prosthetic maintenance

3%

(84/3046)

L 2 C

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 3080
1

Allows variations in cadence

5%

(65/1284)

2

Flexes in a more controlled manner

10%

(126/1284)

3

Lighter in weight

63%

(810/1284)

4

Improved stance control allows less energy expenditure

10%

(131/1284)

5

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

11%

(139/1284)

L 2 C

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 652
1

Less frequent replacement

13%

(149/1135)

2

Less dorsiflexion

9%

(98/1135)

3

Longer duration midstance of gait

40%

(457/1135)

4

Increased ground reaction forces to the contralateral limb

28%

(314/1135)

5

Diminished maximal gait velocity

9%

(106/1135)

L 4 C

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 532
1

Traumatic transtibial amputation

78%

(2176/2780)

2

Vascular transtibial amputation

18%

(498/2780)

3

Vascular thru-knee amputation

1%

(35/2780)

4

Traumatic transfemoral amputation

1%

(20/2780)

5

Vascular transfemoral amputation

1%

(35/2780)

L 2 C

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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 | Tested Concept

QID: 265
1

Single axis foot

1%

(9/1316)

2

Shortened keel articulated dynamic-response foot

20%

(257/1316)

3

Lengthened keel articulated dynamic-response foot

13%

(171/1316)

4

Sagittal split keel articulated dynamic-response foot

61%

(803/1316)

5

Rigid keel nonarticulated dynamic-response foot

5%

(62/1316)

L 3 D

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 287
1

Dorsiflex prosthetic foot

7%

(131/1897)

2

Move foot more posterior

24%

(449/1897)

3

Increase flexibility/softness of keel

2%

(44/1897)

4

Move toe break of prosthesis more posterior

5%

(101/1897)

5

Move foot more anterior

61%

(1151/1897)

L 3 D

Select Answer to see Preferred Response

(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 | Tested Concept

QID: 23
1

Varus strain

3%

(65/2158)

2

Socket pain located medial and proximal

19%

(416/2158)

3

Increased knee extension during stance

35%

(745/2158)

4

Socket pain located lateral and distal

34%

(740/2158)

5

Circumducted gait

8%

(172/2158)

L 4 D

Select Answer to see Preferred Response

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

QID: 1129
1

Low functioning diabetic who needs to transfer bed to chair

0%

(0/1160)

2

Long distance runner with below knee amputation

10%

(111/1160)

3

Elderly male with above knee amputation

1%

(11/1160)

4

Below knee amputee who needs to regularly walk on uneven ground

86%

(1002/1160)

5

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

2%

(29/1160)

L 1 D

Select Answer to see Preferred Response

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

QID: 1314
1

Prosthesis cost

0%

(5/1782)

2

Patient comorbidities

1%

(16/1782)

3

Patient functional status

94%

(1679/1782)

4

Patient gender

4%

(65/1782)

5

Patient age

1%

(13/1782)

L 1 C

Select Answer to see Preferred Response

Evidences (36)
VIDEOS (5)
Topic COMMENTS (14)
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