Lower Limb Prosthesis

1. Lower limb
Prosthesis
Adib Mursyidi Iskandar Mirza
Orthopedics

2. Outline
• Definition
• Aim of prosthesis
• Level of amputations of lower limbs
• Components of prosthesis
• General issues

3. Definition
• Prosthesis
• Device to replace part of the limb or missing limb
“substitute”
• Orthosis
• Externally applied mechanical devices
• Support weakened injured, paralyzed, diseased part
as supplementation
• Prosthetist
• Person skilled in prosthetics and its application

4. Aim ofprosthesis
• Tosubstitute for a lost part
• Torestore lost function
• Comfortable ambulation
• Minimal/reduce of expenditure of energy
•Minimizing the shift of the center of gravity of the
body during gait

5. Level ofamputation
• There are several
levels of lower limb
amputation
• Most common are
transtibial and
transfemoral

6. Component of
prosthesis ofLower
Limbs

7. Parts ofprosthesis
1. Socket
2. Suspension system
3. Knee Joint
4. Shank/pylon
5. Foot/Terminal device

8. Suction&
Mechl close fitting

9. Socket
• Most important part
• Is the connection between the stump
and the prosthesis
• Protects the stump and transmits
forces
• Uncomfortable  rejected
• Contoured sockets fit closer to bone,
muscle, soft tissue
• Provide support and relief

10. Suspensionsystems
• For attaching socket
to body
• Types of suspension
• Sleeve, belt, straps,
or cuff
• Suction prosthesis
• Mechanical close
fitting or silicon sock
helps to maintain
airtight seal

11. Suspension systemsmaterials
• Sleeve – made from
latex
• Cuff – used to hold
prosthesis in residual
limb
• Belt/straps – use a
waist belt with elastic
strap to suspend
prosthesis
• Suction method –
consist of silicon
sleeve with short pin
at the end  will fit
into residual limb and
locks into socket

12. Knee joint
1. Axis system
2. Friction
3. Stabilizer

13. Axissystem
• Single axis
• Axis of prosthetic knee is same as that of weighty
bearing axis
• Flexion easier, but stance phase control difficult
• Polycentric
• Permits momentary axis of knee flexion to change
through the arc of motion  increase knee stability

14. Medium
friction
friction
Constant friction
Frictionmechanism
• Changes knee swing by modifying the speed of knee motion
• Adjust knee swing accordingly
• Constant friction
• Applies uniform resistance throughout swing phase
• Variable friction-cadence control
• Greater friction is applied at early and late swing
• Medium friction
• Oil (hydraulic) friction
• Air (pneumatic)friction
• Allows best gait pattern  best for active patients, but expensiv(ehydraulic)

15. Stabilizers
Manual locking
Stabilizer
Most unit do not have special device
to increase stability
Patient control knee actions through
hip motions by
• Manual locking : prevent knee
flexion
• Friction brake : resist knee flexion
during early stance

16. Shank/pylon

17. • Use to connect the socket to the ankle-foot assembly
• Allow axial rotation and absorb, store, and release
energy
Consist of two types
• Exoskeleton
• soft foam contoured to match other limb with hard
outer shell
• Endoskeleton
• internal metal frame with cosmetic soft covering

18. Ankle-Foot Assembly

19. Ankle FootAssembly
• Designed to provide support during standing/walking
and shock absorption as well
• Consist of 3 categories
• Single axis foot
• Solid ankle cushioned heel (SACH) foot
• Dynamic response
• Articulating
• Non articulating

20. • Ankle hinge allow dorsiflexion and plantar flexion
• Disadvantages
• Poor durability
• Poor cosmesis
Single AxisFoot

21. Solidanklecushionheel(SACH)
• Most widely
prescribed foot
• Due to simple, low
cost and durability
• Uses in patient with
low activity
• Disadvantages – may
overload the non
amputated foot

22. Dynamic response energystoring
foot
• General use for most
normal activities
• Consist of
• Articulating
• Non articulating

23. Articulating
• Allow motion at the level of human ankle
• Indications
• Patients walking on uneven surfaces
• Advantages
• 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

24. Nonarticulating
• 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

25. Prescription ofprosthesis
• Type of prosthesis required
• Level of amputation
• Material of socket
• Suspension mechanism
• Type of cosmesis required

26. GeneralIssues
• 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

27. • 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
• Post operative scar

28. • Painful residual limb
• possible causes include bony prominences, poorly
fitting prostheses, neuroma formation, and insufficient
soft tissue coverage

29. • Ineffective suspension system
• Poor socket fit
• Stump volume changes
• Foot alignment abnormalities