Lower Limbs Prosthesis

Lower Limbs Prosthesis in Orthopedics

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 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 of Lower 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 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. Suspension systems 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 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 Axis system Friction Stabilizer

13. Axis system 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 (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 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 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 hinge allow dorsiflexion and plantar flexion Disadvantages Poor durability Poor cosmesis Single Axis Foot

21. Solid ankle cushion heel (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 energy storing foot General use for most normal activities Consist of Articulating Non articulating

23. Articulating Allow motion at the level of human ankle I ndications P atients 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 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 of prosthesis Type of prosthesis required Level of amputation Material of socket Suspension mechanism Type of cosmesis required

26. 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

27. S kin 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. P ainful 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