Lower Limbs Prosthesis

Lower Limbs Prosthesis

• 1.
  Lower limb Prosthesis Adib MursyidiIskandar Mirza Orthopedics
• 2.
  Outline • Definition • Aimof prosthesis • Level of amputations of lower limbs • Components of prosthesis • General issues
• 3.
  Definition • Prosthesis • Deviceto 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 of prosthesis •To substitute for a lost part • To restore 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 of amputation •There are several levels of lower limb amputation • Most common are transtibial and transfemoral
• 6.
  Component of prosthesis ofLower Limbs
• 7.
  Parts of prosthesis 1.Socket 2. Suspension system 3. Knee Joint 4. Shank/pylon 5. Foot/Terminal device
• 8.
  Suction& Mechl close fitting
• 9.
  Socket • Most importantpart • 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.
  Suspension systems • Forattaching 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 systems materials •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. Axissystem 2. Friction 3. Stabilizer
• 13.
  Axis system • Singleaxis • 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 (hydraulic) friction Constant friction Friction mechanism •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 expensive
• 15.
  Stabilizers Manual locking Stabilizer Most unitdo 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 toconnect 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 Foot Assembly •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 hingeallow dorsiflexion and plantar flexion • Disadvantages • Poor durability • Poor cosmesis Single Axis Foot
• 21.
  Solid ankle cushionheel (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 motionat 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.
  Non articulating • Haveshort 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 of prosthesis •Type of prosthesis required • Level of amputation • Material of socket • Suspension mechanism • Type of cosmesis required
• 26.
  General Issues • Chokesyndrome • 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 residuallimb • possible causes include bony prominences, poorly fitting prostheses, neuroma formation, and insufficient soft tissue coverage
• 29.
  • Ineffective suspensionsystem • Poor socket fit • Stump volume changes • Foot alignment abnormalities