1. Transtibial Amputation
Sarah Kitchin
Erica Patterson

2. Living Without A Leg

3. Outline Statistics on Amputation
Transtibial and Transfemoral Differences
Fitting
Balance
Biomechanics
Conclusion

4. Amputation Facts 1,285,000 People Living with Limb Loss in The U.S.
4.9 per 1,000 people
Of Those 1,285,000 People:
39,479 were Transtibial Amputations
36,478 were Transfermoral Amputations (American Amputee Coalition of America ‘96)
Most recent data collected, done through a National Health Survey
Limb loss generally refers to the absence of any part of an extremity (arm or leg) due to surgical or traumatic amputation.  The term, Limb Differences, is used in reference to the congenital absence or malformation of limbs.

5. Differences between Transtibial and Transfemoral Amputations
Known as above the knee amputations
Surgeon’s goal is to leave as much residual limb as possible, preserve the adductor muscles, and the remaining soft tissue. (Biomed, ’03)

6. Differences between Transtibial and Transfemoral Amputations (Cont.)
Transtibial Amputations:
Known as Below The Knee Amputations
The Surgeon’s goal is to leave a cylindrical shaped well-padded residual limb.
Using the gastrocnemius and soleus muscles to create a muscular flap.
Surgery provides some challenges (In Motion, ’03)
Biggest muscles in the legs
Challenge is the lack of padding on the front of the lower leg. Surgically, can’t add padding to that area. Can bring some muscle over the end of the residual limb from the back and side and some newer reconstructive techniques extend the posterior flap to provide even more padding. But still remains exposed and is sensitive.
Another challenge is when a nerve is severed during amputation, it will form an ending of nerve fibers called a neuroma. They have to position the nerve ending in well-cushioned soft tissue that’s away from the incision, any scar tissue, areas of pressure and throbbing vessels. There, the nerve ending will irritated by traction, pressure from the prosthetic socket or any other unwanted source of contact. Goal is to retain as much of the useful remaining nerve function in the residual limb as possible, while also carefully managing the nerves to minimize nerve scarring and painful neuromas.

7. Fitting An exact mold of the residual limb does not make a good socket
Indent in the region around the patellar tendon
Many different types of sockets
Foam of silicone
Hard
Soft (Smith, ’03)
First Bullet: Socket must be indented where people can take extra weight and relieved or pulled out over sensitive areas.
Second Bullet: Can take weight, so indent there
Third Bullet: Foam or silicone liners to provide support-can provide comfort and accommodate minor changes in the size of the residual limb; disadvantage: sweating and not comfortable in hot, humid weather.
Hard Sockets: cotton or wool sokcs between the leg and the socket and are more durable and easier to clean
Soft: supported by a rigid outside frame. Can change shape to accommodate the contractions of the underlying muscles and can be useful for limbs that are scarred or difficult to fit.

8. Study on One Type of Socket
5 Unilateral transtibial amputees
Placed in a pressure chamber
Produces equally distributed pressure at the stump/socket interface
Comfortable and pressure evenly distributed
Still Controversial (Goh, ’03)

9. Prosthetic Alignment
Alignment is the spatial relationship between the prosthetic socket and foot.
Purpose:
Position the prosthetic socket with respect to the foot so that adverse patterns of force applied to the residual limb are avoided
Produce a normal pattern of gait (Noelle, ’03)
"Alignment" refers to the spatial relationship between the prosthetic socket and foot. The main purpose of alignment is to position the prosthetic socket with respect to the foot so that undesirable patterns of force applied to the residual limb are avoided. A second purpose is to produce a normal pattern of gait.

10. Prosthetic Alignment (Noelle, ’03)
Figure 1 shows a standard anterior-posterior alignment in the sagital plane. The gravitational line (90 degrees to the ground) should fall through the center of the socket, anterior to the ankle joint axis, through weight bearing area of the foot between the middle of the weight bearing surface of the heel.
Figure 2 shows the standard flexion angle of the socket in the sagital plane. 5 degrees of socket flexion incorporated into an initial set-up help assist better loading in the socket and help create a smoother gait pattern.

11. Prosthetic Alignment Study
Enhance residual limb comfort and maximize walking capabilities in persons with lower extremity amputation
Study suggest prosthetic alignment does promote steady and comfortable walking with a lower extremity prosthesis
Prosthetic misalignment may well lead to instability, discomfort, increased limb loading, and tissue breakdown when applied over a long period of time (Pinzur, ’95).
14 unilateral transtibial amputees.
Vertical ground reaction force were recorded in neutral prosthetic alignment and in 10 degrees of prosthetic socket valgus, flexion, and extension vs. those w/ misalignment.
Significant differences were found in the stance phase time, peak vertical ground reaction time, and impulse when comparing misalignment w/ neutrally aligned limbs.

12. Balance and Stability Study
Significant differences found between TTA and controls during equilibrium and movement studies.
Transition from bipedal to monopedal
High failure rate for TTA
Same difficulty on sound and prosthetic limb (Viton 00’)
Utilize remaining muscles
Work on speed of contraction, not maximal force of contraction (Gailey 03’)

13. Walking With a Prosthetic
Prosthetic Walking

14. Biomechanics - Absorption Phase
Reduction in ground reaction force
Significant difference in knee angles found at heel strike. (Isakov 00’)
Prosthetic absorbs and generates less energy which results in
A more passive limb
Absorption by soft tissue in socket
Presence of isometric contraction by muscles
So as foot strikes, a backward force is instantly created by prosthetic-side hip muscles.
(Gailey 02’)

15. Biomechanics - Deceleration Phase
Hip abductors and adductors and knee extensors muscles are main source of absorption. (Sadeghi 01’)
Fewer gait problems are involved in the swing phase than with the stance.
(Walter 04’)

16. Biomechanics - Acceleration Phase
Hip extensor effort is main compensation of propulsion reduction. (Pailler 04’)
Amputation of ankle reduces the ability of power to be produced through plantar flexion.
(Sadeghi 01’)

17. Biomechanics Summary Longer motions for amputated side
Step length
Step time
Swing time
Shorter motions for amputated side
Stance time
Single support time
(Isakov 00’)

18. Energy Cost Studies Energy cost depends on Gait speed Efficiency
Not on displacement of center of mass (Detrembleur 05’)
Energy consumption
For transfemoral amputees is more significant than that of transtibial amputees.
Is affected by prosthetic alignment
Is not affected by the use of different prosthetic feet
(Schmalz 02’)

19. Energy Expenditure for Amputation
Amputation Level
Energy Above Baseline, %
Speed, m/min
Oxygen Cost, ml/kg/m
Long Transtibial 10 70
.17
Average Transtibial 25 60
.20
Short Transtibial 40 50
Bilateral Transtibial 41
Transfemoral 65
.28
Wheelchair
0-8
.16
The higher the level of lower limb amputation, the greater the energy expenditure required for walking. As the level of amputation moves proximally, the walking speed of the individual decreases, and the oxygen consumption increases. For most people who have undergone transtibial amputations, the energy cost for walking is not much greater than that required for persons who have not undergone amputations. For those who have undergone transfemoral amputations, the energy required is 50-65% greater than that required for those who have not undergone amputations. Additionally, those with PVD who have undergone transfemoral amputations may have cardiopulmonary or systemic disease and require maximal energy for walking, making independence difficult to maintain. Biomed
The length of the residual femur is inversely related to the energy consumption in walking with a prosthesis (transfemoral)
(Janos 05’)

20. Summary Transtibial amputations are more common
then transfemoral amputations.
There is not one best type of socket fitting
Balance and stability has same difficulty whether on sound or prosthetic limb
Biomechanics are compensated by use of muscles and the combination of longer and shorter motions using amputated side.
Energy costs depend on gait speed and efficiency, not displacement of center of mass

21. References
Amputation and Limb Deficiency. < 14 November 2005.
Amputee Coalition of America. < 28 November 2005.
Goh, J.C.H., Lee, P.V.S, Chong, S.Y. “Stump/Socket Pressure Profiles cast prosethetic socket.” Clinical Biomechanics. 18 (2003):
Detrembleur, Christine. “Relationship Between Energy Cost, Gait Speed, Vertical Displacement of Centre of Body Mass and Efficiency of Pendulum-Like Mechanism in Unilateral Amputee Gait.” Gait & Posture. 21 (2005):
Gailey, Robert. “The Biomechanics of Amputee Running.” The O&P Edge. October 2002.
Gailey, Robert. “Stability Within the Socket Creates Stable World.” The O&P Edge. September 2003.
Information about Transtibial Prosthetics. < 28 November 2005.
Isakov, E. “Trans-tibial Amputee Gait: Time-distance Parameters and EMG Activity.” Prosthetics and Orthotics International. 24 (2000):
Janos, Ertl P. “Amputations of the Lower Extremity.” eMedicine January 2005.
Miller, William C. “Balance Confidence Among People With Lower-Limb Amputations.” Journal of the American Physical Therapy Association. (2002).

22. References (Cont.)
Nadollek, Heidi. “Outcomes After Trans-Tibial Amputation: The Relationship Between Quiet Stance Ability, Strength of Hip Abductor Muscles and Gait.” Physiotherapy Research International. 7 (2002):
Noelle, Lannon. “Trans-tibial Alignment: Normal Bench Alignment.” Ortholetter: International society for Prosthetics and Orthotics. < July 2003.
Nolan, L. “The Functional Demands On the Intact Limb During Walking for Active Trans-Femoral and Trans-Tibial Amputees.” Prosthetics and Orthotics International. 24 (2000):
Pailler, D. “Evolution in Prostheses for Sprinters With Lower-Limb Amputation.” Annales de Readaptation et de Medecine Physique. 47 (2004):
Pinzur, Michael S., Cox, William. “The Effect of Prosthetic Alignment on Relative Loading in Person With Trans-tibial Amputation: A Preliminary Report.” Journal of Rehabilitation Research & Development. 32 (1995):
Sadeghi, H. “Muscle Power Compensatory Mechanisms In Below-Knee Amputee Gait.” American Journal of Physical Medicine & Rehabilitation. 80 (2001):
Shmalz, Thomas. “Energy Expenditure and Biomechanical Characteristics of Lower Limb Amputee Gait: The Influence of Prosthetic Alignment and Different Prosthetic Components.” Gait & Posture. 16 (2002):
Smith, Douglas G. M.D. “Transtibial Amputations: Successes and Challenges.” Notes from the Medical Director.
Viton, J M. “Equilibrium and Movement Control Strategies in Trans-Tibial Amputees.” Prosthetics and Orthotics International. 24 (2000):
Walter, Ellis. “Gait Analysis After Amputation.” eMedicine. April 2004.