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prosthetics

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Shruti Patil

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.

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Prostheses The principal lower limb prostheses are • Partial foot prostheses • Syme’s prosthesis • Transtibial prostheses • Transfemoral prostheses • Knee disarticulation • Hip disarticulation
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
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.
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.
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.
Parts of Trans-tibial Prostheses 1. Foot-ankle assembly 2. Socket 3. Shank 4. Suspension component
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
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
SACH FOOT (Solid ankle Cushion Heel)
SAFE FOOT ( Solid Ankle Flexible Endoskeleton)
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
ENDOSKELETON EXOSKELETON
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
prosthetics
prosthetics
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
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.
prosthetics
prosthetics
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
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.
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
prosthetics
prosthetics
PTB Transtibial prosthesis PTB SC/SP
prosthetics
Trans-femoral prosthesis Components • Foot-ankle assembly • Shank • Knee unit • Socket • Suspension device
Knee Unit Knee units have four features: • Axis • Friction mechanism • Extension aid • Mechanical stabilizer
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
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
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
Knee Unit: FRICTION MECHANISM Medium  Sliding friction  Fluid friction - hydraulic friction - pneumatic friction  Microprocessor controls
Knee Unit: EXTENSION AID • A mechanism to assist knee extension during latter part of swing phase • Types- i. Elastic webbing ii. Internal extension aid
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
SOCKET Pressure tolerant areas • Gluteal musculature • Sides of the thigh • And distal end of amputated limb Pressure sensitive areas • Pubic symphysis • Perineum
prosthetics
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.
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
Suspension in Transfemoral Prosthesis
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
DIFFERENT TYPES OF LOWER LIMB PROSTHESIS
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
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)
prosthetics
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prosthetics

  • 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
  • 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
  • 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
  • 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)

Editor's Notes

  1. 1 retard excessive knee flexion 2 permit knee to swing easily 3 to dampen impact