This document describes various types of lower limb prostheses. It discusses partial foot prostheses, Syme's prosthesis, transtibial prostheses, transfemoral prostheses, knee disarticulation, and hip disarticulation prostheses. For transtibial prostheses, it outlines the components which include the foot-ankle assembly, socket, shank, and suspension. It also describes the types and purposes of various prosthetic feet and knees. For transfemoral prostheses, it discusses the components of the prosthesis and types of sockets and suspension systems.

1. Prostheses
The principal lower limb prostheses are
• Partial foot prostheses
• Syme’s prosthesis
• Transtibial prostheses
• Transfemoral prostheses
• Knee disarticulation
• Hip disarticulation

2. Partial Foot Prostheses
• Purpose
1. Restore foot function particularly in walking
2. Simulate the shape of the missing foot
segment
• Indications
1. Loss of one or more toes
2. Transmetatarsal amputation
3. Amputation or disarticulation through tarsals

3. Partial Foot Prostheses
• Loss of one or more toes
 Pad the toe section to improve appearance of the upper
section of the shoe
 Arch support to maintain alignment of amputated foot.
• Transmetatarsal amputation
 Plastic socket to protect amputated ends of the metatarsals
 Rigid plate restores the foot length
 Toe filler
 Rocker bar at the bottom of the prosthesis to aid late stance.

4. Partial foot prostheses
• Amputation or disarticulation through tarsals
Prostheses used in transmetatarsal
amputation augmented with a plastic calf
shell which is strapped around the leg.

5. Trans-tibial Prostheses
Trans-tibial level refers to -
• Amputation in which tibia and fibula are
transected
• Retention of anatomical knee joint
• Intact motor and sensory functions.
• Indicated in vascular diseases.

6. Parts of Trans-tibial Prostheses
1. Foot-ankle assembly
2. Socket
3. Shank
4. Suspension component

7. Foot-ankle assembly
Uses
• Restores contour of the foot
• Absorbs shock at heel contact
• Plantarflexes in early stance
• Simulates metatarsophalangeal
hyperextension in late stance phase
• In neutral position during swing phase

8. Foot-ankle assembly
 Types
• Non-articulated feet
1. SACH foot (solid ankle cushion heel)
2. SAFE foot (stationary attachment flexible
endoskeleton)
• Articulated feet
1. Single-Axis feet
2. Multiple-Axis feet

9. SACH FOOT (Solid ankle Cushion Heel)

10. SAFE FOOT ( Solid Ankle Flexible Endoskeleton)

11. Shank
 Substitute for human leg
 Restores length and shape
 Located above foot-ankle assembly and
below socket in transtibial prostheses
 Types
• Exoskeleton shank
• Endoskeleton shank

12. ENDOSKELETON EXOSKELETON

13. Socket
Uses
• Maximum distribution of load
• Assist in venous blood circulation
• Provide tactile feedback
Patellar tendon bearing (PTB) socket has a
prominent indentation over patella tendon.
Socket has reliefs and build-ups

16. Structure of Socket
• Reliefs-concavities in the socket over areas
contacting sensitive structures such as bony
prominences.
• Located over
i. fibular head,
ii. tibial crest,
iii. tibial condyles and
iv. anterior-distal tibia.
• Posterior brim is trimmed to provide room for
hamstring tendons

17. Structure of Socket
• Build-ups- convexities n the socket over areas
contacting pressure-tolerant tissues.
• Located over
i. belly of gastrocnemius,
ii. patellar tendon,
iii. proximomedial tibia (pes anserinus) and
iv. tibial and fibular shafts.

20. Alignment of Socket
On the shank in slight flexion and in slight lateral
tilt.
• Flexion
i. enhances loading on patellar tendon,
ii. prevent genu recurvatum,
iii. resist tendency of amputated limb to slide
too deeply into socket,
iv. facilitates contraction of quadriceps muscle
• Lateral tilt reduces loading on fibular head

21. Types of socket
• Lined socket
i. Made of polyethylene foam liner, silicone
ii. Liner adds or reduces volume of the socket
iii. Adds to the bulk of the prosthesis
iv. Heat insulator
v. Reduces risk of abrasion between socket and skin
• Unlined socket
i. Made of thermoplastic material
ii. Usually given when stump has stabilized in volume
iii. Easier to clean
iv. Difficult to alter the shape of the socket.

22. Suspension
• Prosthesis requires some from suspension to hold
it in place while walking or climbing stairs or
jumping.
• Types of suspension
i. Cuff variants
ii. Distal attachment
iii. Brim variants
iv. Thigh corset
v. Vacuum-assisted socket system

25. PTB
Transtibial
prosthesis
PTB SC/SP

27. Trans-femoral prosthesis
Components
• Foot-ankle assembly
• Shank
• Knee unit
• Socket
• Suspension device

28. Knee Unit
Knee units have four features:
• Axis
• Friction mechanism
• Extension aid
• Mechanical stabilizer

29. Knee Unit: AXIS SYSYTEM
Two types of knee units
i. Single axis
ii. Polycentric linkage
a) 4 or more pivoting bars
b) Provide greater stability
c) center of knee rotation in posterior to
weight bearing line

30. Knee Unit: FRICTION MECHANISMS
• Change the knee swing by modifying speed of
knee motion during swing phase
• Affect knee swing according to walking speed.
• Two factors affecting friction mechanism are
i. Time during swing phase when friction
affects knee joint
ii. medium through which mechanism operates

31. Knee unit:FRICTION MECHANISMS
• Constant friction
i. Clamp grasping knee joint
ii. Amount of friction is unvarying in swing phase
iii. Manually adjusted to loosen or tighten
• Variable friction
i. Amount of friction is variable in swing phase
ii. Early swing –high friction
iii. Mid-swing –friction diminishes
iv. Late swing -friction increases

32. Knee Unit: FRICTION MECHANISM
Medium
 Sliding friction
 Fluid friction
- hydraulic friction
- pneumatic friction
 Microprocessor controls

33. Knee Unit: EXTENSION AID
• A mechanism to assist knee extension during
latter part of swing phase
• Types-
i. Elastic webbing
ii. Internal extension aid

34. Knee Unit:STABILIZERS
• To increase stability of knee unit
• Hip motion controls knee action, aided by
alignment of knee in relation to other
components of prosthesis
• Knee joint is aligned posterior to line
extending from trochanter to ankle (TKA line)
• Types
i. Manual lock
ii. Friction brakes

35. SOCKET
Pressure tolerant areas
• Gluteal musculature
• Sides of the thigh
• And distal end of
amputated limb
Pressure sensitive areas
• Pubic symphysis
• Perineum

37. Types of socket
Quadrilateral socket
i. Post wall-ischial tuberosity +
gluteal muscles
ii. Ant wall- applies post
directed pressure
iii. Lat wall- aid in medio-lateral
stabilization
iv. Med wall
Reliefs
i. Antero-medial
ii. Postero-medial
iii. Antero-lateral
iv. Postero-lateral
Ischial Containment socket
i. Contoured adducted
trochanter-controlled
alignment method.
ii. Covers ischial tuberosity
and part of ischiopubic
ramus to increase stability.
iii. To increase frontal stability
medial-lateral width is
narrow.
iv. Lateral wall covers greater
trochanter.

38. Suspension
Suction suspension
i. Refers to pressure differences inside and outside the
socket.
ii. In suction suspension,(int socket press) < (ext pressure),
therefore atm press. causes the socket to remain on the
thigh
iii. One-way air-release valve enables residual air to be
expelled
iv. Types of suspension are
a) total suction,
b) partial suction and
c) no suction

39. Suspension in Transfemoral Prosthesis

40. FIT AND ALIGNMENT
• FIT
i. Snug fitting to minimize chaffing and
maximize control
• ALIGNMENT – slight socket flexion
i. Facilitates contraction of hip extensors
ii. Reduce lumbar lordosis
iii. Allows equal step length

41. DIFFERENT TYPES OF LOWER LIMB PROSTHESIS

42. KNEE DISARTICULATION PROSTHESIS
Excellent prosthetic control
because
i. Thigh leverage is
maximum
ii. Body weight can be
borne through distal end
of femur
iii. Epicondyles provide
rotational stability

43. HIP DISARTICULATION PROSTHESIS
• Indications
i. Amputation above greater trochanter (short
transfemoral)
ii. Removal of the femoral head from
acetabulum (hip disarticulation)
iii. Removal of femur and portion of pelvis
(transpelvic amputation)

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