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PROSTHESIS FOR HIP DISARTICULATION AMPUTEES - STUDY

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Prosthetic leg for hip-disarticulation amputees. This amputation represent less than 1% of the amputee community. Only 20% of hip amputees ambulate full time with a prosthetic leg. Analysis of the biomecanics of a Canadian type prosthetic leg. Full kinematics analysis and comparison between polycentric and single axis knees. Study of the toe clearance with polycentric knees.

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PROSTHESIS FOR HIP DISARTICULATION AMPUTEES - STUDY

  1. 1. This presentation contains complex animations, graphics and video elements These features are not available when viewing the presentation online Download the files and view it on your computer with PowerPoint
  2. 2. PROSTHETICS • A Hip-Disarticulation consist of the removal of the entire leg at the hip joint and results in the loss of 3 major limb joints: The ankle, the knee and the hip joint • Douglas G. Smith, MD comments in an article in the magazine In-Motion: … “Trying to overcome the loss of three weight-bearing joints, rather than one or two, is extremely complicated. Living with a transfemoral amputation is about 10 times as tough as living with a transtibial amputation, and living with a hip- or pelvic-level amputation is perhaps 100 times harder. Walking, standing, and even sitting balance – something that most of us take for granted – are greatly affected by amputations at the hip or pelvis”
  3. 3. PROSTHETICS 1. Malignant musculoskeletal tumors (most often in younger patients) 2. Limb ischemia (perivascular disease and complications to diabetes) 3. Trauma (such severe traumas often result in the death of the patient) 4. Severe lower limbs infections (chronic skin or bone infection) As a result. . . . . . .
  4. 4. PROSTHETICS • Most prosthetist have little experience with this type of amputation • Only 20% of hip amputees use a prosthetic leg full-time (i.e. 8 to 12 hr./day) • From these 20%, only a small minority use a prosthetic leg without a cane or crutch • This small minority of full time users without walking aids consists primarily of the young patients with malignant tumors. • There is a persistent belief within the medical community that most middle aged hip-disarticulation amputees will ambulate with crutches or a wheelchair only!!! * Consent is is a bit of a misnomer as I had to choose between 1) hip-disarticulation or 2) slowly dying from infection or 3) slowly dying from the I.V. Vancomycin (antibiotic of last resort) eating my body away. I REMEMBER CLEARLY THE SURGEON EXPLAINING TO ME, AS I WAS SIGNING THE CONSENT* PAPERS PRIOR TO THE SURGICAL PROCEDURE, THAT I WAS GOING TO SPEND THE REST OF MY LIFE ON CRUTCHES
  5. 5. PROSTHETICS • I am not an athlete (165lbs/5’11”), and certainly not young (52+), yet….. • I am a full-time user AND I walk without a cane and… • I live a full life and do just about everything I want. • Granted, there are some limitations. Yes, I can’t play tennis anymore. Big deal! Yes, I can’t ride motorcycles anymore. That, I do miss indeed but it’s not the end of the world. • Is the prosthesis comfortable? Hell no! But it beats using crutches all day. • Biggest problem with using crutches is that we loose the use of our hands. People are always surprised when I say this. What I mean is that we cannot carry things easily when using crutches.
  6. 6. PROSTHETICS • The key to success is to become deeply involved in the process. • It is easy to believe that “This is as best as it can be!”. These highly trained professional prosthetists have done their best but I still can’t walk with the damn’ leg. It hurts, I keep on falling (This I did. 3 broken wrists, 1 rib…). Therefore, I must be the problem. I am not just good enough. I am too old. I am not trying hard enough. I am too weak, etc… • True! This highly trained professionals try hard but… • They lack experience in this domain. • They don’t have the time to do it right and, • These types of prosthetic legs are finicky to set up. It takes days of incremental adjustments to get it just right. (i.e. Efficient to use (not tiring) and stable) • For example, on my current leg, there are 44 set-screws and other adjustments, all interacting with each other, altering the geometry and other parameters of the leg.
  7. 7. PROSTHETICS - SOCKET • The first socket was a disaster. Eventually, my prosthetist relented and accepted to build a second one at no cost. Including many modifications I had suggested during numerous discussions. • This socket is much better but by no mean GOOD. • From what I have read in several technical articles, it could be much better. • The problem consist of: • 1) Finding a prosthetist, that actually knows what he is talking about. Not so easy, as they all claim to be experts…. • 2) COST. For most non amputees, it is always a surprise. A socket cost around $12,000! (Yes, you are reading right!) and, the icing on the cake is… MOST insurances do not pay at all, or pay only a minor fraction of the cost. Prosthetics are included in insurance contracts under durable medical equipment*. YES, it is covered but maximum payment is limited to……. $2,000/year. Nobody check these things unless… they lose a limb. *BTW: I wish they were durable. I have yet to find a knee that last more than 2 years!!
  8. 8. PROSTHETICS - SOCKET Side View Back View Carbon Fiber Socket Deep recesses over the iliac crest provides positive support, limiting “pumping” and increasing toe clearance (my idea) Otto Bock 7E7 hip joint (titanium) Triple ski-boots type ratchets and straps providing a TIGHT fit of the socket around the pelvis for improved “feel” and control Non stretchable heavy duty straps preventing change in socket geometry with time Note: I did the strapping system and ratchet buckles. The dimensions of the straps are critical in maintaining the proper shape of the socket. Earlier system used fabric straps that used to stretch over time.
  9. 9. PROSTHETIC COMPONENTS The cost of prosthetic components is just astronomical A typical knee will cost between $10,000 and $30,000 A “computerized” knee between $30,000 and $40,000 A foot between $2,000 and $5,000 A typical pyramid adapter $400 (Al) or $800 (Ti)
  10. 10. PROSTHETIC COMPONENTS 2014 CHEVROLET MALIBU Incredibly complex machine with thousands of parts. The results of a century of research in advanced materials and complex alloys with cutting edge electronics and unparalleled durability with minimum service. 4-cylinder 2-liter 259HP turbocharged engine, 6 speed automatic transmission, curb weight 3,547lbs $30,000 TEH-LIN Knee GRAPHLITE frame ENDOLITE hydraulics A few bits or carbon fiber A handful of ball bearings A simple hydraulic cylinder Curb weigh 5lbs MAKE SENSE DOESN’T IT?
  11. 11. HD PROSTHESIS The first challenge with a hip disarticulation (HD) prosthetic leg is: WHERE TO LOCATE THE HIP JOINT? The Canadian-Type HD prosthesis was developed in 1954. The hip joint is located on the front of the socket. It is connected to the knee joint with an angled tube in such a way that the axis of the knee is posterior to the single equivalent force. Single Equivalent Force (~Projection of CG)
  12. 12. HD PROSTHESIS Single Equivalent Force (Projection of CG) Knee Axis
  13. 13. HD PROSTHESIS Knee Joint Knee Axis SEF The knee axis is posterior to the SEF line. The resulting moments will force the knee to bend in the direction indicated by the arrows. However, the knee is already fully extended and cannot extend further. THE KNEE IS STABLE 1 2 3
  14. 14. HD PROSTHESIS The SEF line is posterior to the knee axis. The resulting moments will force the knee to bend in the direction indicated by the arrows. 1 The knee will buckle under load. 2 THE KNEE IS UNSTABLE3 Knee Joint Knee Axis SEF ALIGNMENT is the process of setting up the geometry of the leg
  15. 15. THE BIOMECAHNICS OF AN HD PROSTHESIS* * From Charles W. Radcliffe Note that at heel strike the knee is almost unstable. AK amputees use their extensor muscles to increase stability. HD amputees CAN’T!! SEF posterior to knee axis. The knee bends. Bump stop in hip joint helps bending the knee
  16. 16. PROSTHETIC COMPONENTS Hip Joint (Ti) Male/female pyramid Adapter to refine hip/knee Geometry (Ti) Angled pyramid adapter (15°) (Ti) Knee rotator (Critical for driving) Sliding adapter (Ti) GRAPHLITE/ENDOLITE Single Axis Knee Height adjustable adapter (Ti) Sliding adapter (Ti) OSSUR Flex Foot (Carbon Fiber)
  17. 17. Hip Joint (Ti) Male/female pyramid Adapter to refine hip/knee Geometry (Ti) Angled pyramid adapter (15°) (Ti) Knee rotator (Critical for driving) Sliding adapter (Ti) GRAPHLITE/ENDOLITE Single Axis Knee Height adjustable adapter (Ti) Sliding adapter (Ti) OSSUR Flex Foot (Carbon Fiber) Single axis knees are not recommended for HD prosthesis. True but, A WELL ALIGNED single axis knee works very well in an HD prosthesis
  18. 18. Pylon (al) Angled pyramid adapter (10°) (Ti) Knee rotator (Critical for driving) Offset adapter (Ti) THE-LIN 5-BAR KNEE CARBON Pylon with Ti adapter Carbon Shock Absorber OSSUR Reflex VSP Foot HD Prosthesis using the TEH-LIN TGK-5PSO Polycentric 5-Bar Pneumatic knee with adjustable centroid
  19. 19. L l HD – TOE CLEARANCE KNEE JOINT FOOT GROUND FLOOR T
  20. 20. HD – TOE CLEARANCE KNEE JOINT FOOT GROUND FLOOR T T = R-L 𝑻 = 𝒍 𝟐 + 𝑳 𝟐 − 𝑳 Toe Clearance T Toe clearance is always an issue for all above knee (AK) amputees and a very big issue for HD amputees. If the toes hit the floor during the swing phase, the knee may not lock at heel strike and buckle under load, resulting in a fall. AK amputees have good control of their prosthetic knee and the interface socket/stump provides enhanced proprioception. HD amputees do not! To minimize such event, it is customary to shorten the prosthetic leg. However, this results in a non symmetrical gait and pronounced limp.
  21. 21. HD – TOE CLEARANCE One way to minimize the toe clearance is to increase L. The graph shows that by increasing L by 200mm, we gain 8mm of toe clearance. That may not sound a lot but I can clearly feel a change of 1 or 2mm in length. However, for practical and cosmetic reasons, we want the prosthetic knee to be at the same level as the “good” knee and for the same reasons we want the prosthetic foot to be the same size as the good foot. 18 20 22 24 26 28 30 500 520 540 560 580 600 620 640 660 680 700 C(mm) L (mm) Clearance C as a function of L C l=170mm L=500-700mm SO, WHAT DO WE DO?
  22. 22. HD – TOE CLEARANCE THE POLYCENTRIC KNEE All polycentric knees commercially available are 4-bar designs. The “5-bar” knees are 4-bar knees with adjustable geometry. In the 4-bar linkage A-B, C-D, the rotation center of the segment B-D relative to A-C is located at the intersection the lines passing through A-B and B-D. This virtual center of rotation is called the centroid (or centrode by the O&P community) l=170mm L>500mm Centroid Centroid Trajectory The centroid is not fixed but is a function of the angle of the knee. Note that the centroid moves in the vertical direction AND in the posterior/anterior direction. This has important consequences in term of alignment and stability. The polycentric knee allows to increase the distance L without moving the knee. It is possible to gain up to 10mm in toe clearance with some polycentric knees.
  23. 23. HD – TOE CLEARANCE T KNEE JOINT FOOT GROUND FLOOR T = R-L 𝑻 = 𝒍 𝟐 + 𝑳 𝟐 − 𝑳 Toe Clearance T We need to build a foot/shin/knee assembly in such a way that the toes will rise in the final phase of the swing. Between α = 0 and α = α 1 , β < 90° For α > α 1 β = 90° β = 90° under load Or, we move the foot! α α1 β=90°
  24. 24. HD – TOE CLEARANCE T KNEE JOINT FOOT GROUND FLOOR T = R-L 𝑻 = 𝒍 𝟐 + 𝑳 𝟐 − 𝑳 Toe Clearance T We need to build a foot/shin/knee assembly in such a way that the toes will rise in the final phase of the swing. Between α = 0 and α = α 1 , β < 90° For α > α 1 β = 90° β = 90° under load Or, we move the foot! α α1 β=90°
  25. 25. HD – TOE CLEARANCE Such a knee/foot system exists. PROTEOR, a French manufacturer developed such system: The 1P50R Hydracadence II. Unfortunately, PROTEOR is poorly distributed in the US. Nevertheless, I managed to convince my prosthetist to order such a knee and… what happened then is a disgrace. The knee was defective, we couldn’t get tech-support in English, they did not answer any request and eventually blamed the prosthetist for the faulty knee demanding $2,000 for repair. Made me proud to be French! 1P50R Hydracadence II
  26. 26. HD – TOE CLEARANCE The 1P50R Hydracadence II is a single axis hydraulic knee. The coupling between knee angle and foot angle is hydraulic. In addition, to its unique ability to improve toe clearance, the system provides a smoother and safer transition to load bearing at heel strike. It is a very clever system and it’s a shame that their service and support is so poor in the US. I propose to build a similar system using a simpler mechanical coupling between knee and foot with the following requirements: Toe rise for 0 < α < α 1 (terminal phase of swing) and rigid foot/knee coupling (90°) for α = 0 and α > α1 1P50R Hydracadence II
  27. 27. HD – TOE CLEARANCE The kinematics of a hip-joint/knee/foot with such requirements is beyond the paper and pencil approach. Three possibilities 1) LEGO YES! I hear you laughing but you would be surprised to see what can be done with the LEGO technics pieces. I even built a functioning clock escapement to impress the kids. (Photos lost unfortunately) 2) COMPUTER MODELING There are many software solutions. However, most are designed for the professional community and very expensive. In addition, the learning curve with such programs is extremely steep. GOOGLE created SKETCHUP, a FREE 3D modeling package. It is powerful yet, relatively easy to learn. SKETCHYPHYSICS is a free plugin for SKETCHUP based on the NEWTON SDK physics engine from NEWTON GAME DYNAMICS. SKETCHYPHYSICS is VERY buggy but… it is FREE. 3) DO THE MATHS Solve analytically the motion of each part of the system (Major Trigonometric Cluster F*@!&). Then, simulate in EXCEL.
  28. 28. HD – TOE CLEARANCE – KINEMATICS MODELING First test of kinematics modeling with Google Sketchup and Sketchyphysics. Sketchup was primarily designed for architects but can be used for other applications. 3D modelling is never easy but Google developed a user friendly interface. Sketchyphysics on the other hand is obscure and buggy but is the only free application I could find.
  29. 29. Four-Bar Linkage Animation using Google Sketchup and Sketchyphysics Plug-In
  30. 30. Four-Bar Linkage Animation using Google Sketchup and Sketchyphysics Plug-In
  31. 31. Four-Bar Linkage Animation using Google Sketchup and Sketchyphysics Plug-In
  32. 32. Four-Bar Linkage Animation using Google Sketchup and Sketchyphysics Plug-In
  33. 33. Four-Bar Linkage Animation using Google Sketchup and Sketchyphysics Plug-In
  34. 34. Four-Bar Linkage Animation using Google Sketchup and Sketchyphysics Plug-In
  35. 35. Four-Bar Linkage Animation using Google Sketchup and Sketchyphysics Plug-In
  36. 36. HD – TOE CLEARANCE – KINEMATICS MODELING
  37. 37. Model or a 5-bar linkage modelled in Sketchup8 and Rendered in KERKYTHEA KERKYTHEA is extremely powerful. It is free and… TOTALLY user UNFRIENDLY…
  38. 38. Model or a 5-bar linkage modelled in Sketchup8 and Rendered in KERKYTHEA KERKYTHEA is extremely powerful. It is free and… TOTALLY user UNFRIENDLY…
  39. 39. Model or a 5-bar linkage modelled in Sketchup8 and Rendered in KERKYTHEA KERKYTHEA is extremely powerful. It is free and… TOTALLY user UNFRIENDLY…
  40. 40. Model or a 5-bar linkage modelled in Sketchup8 and Rendered in KERKYTHEA KERKYTHEA is extremely powerful. It is free and… TOTALLY user UNFRIENDLY…
  41. 41. HD – KINEMATICS TEH-LIN, a Taiwanese manufacturer, recently introduced two 5-bar knees. These knees do not use a proper 5-bar linkage but offer the possibility of altering the 4-bar geometry and the centroid trajectory through the motion of the knee. It is difficult to measure accurately the geometry of the 4- bar linkage and their documentation is rather vague on the effect of the 5-th bar adjustment on knee stability and toe clearance. I proposed the following methodology to measure the centroid trajectory for each knee.
  42. 42. HD – KINEMATICS MEASUREMENTS 1. Build a test jig consisting of a sheet of ½” plywood on a stand and a pyramid adapter to support the knee under test and a 30”x20” foam board 2. Build a test foot made of a ½”x1 ½” piece of wood with three 12mm holes at the normal toe and heel location and a pyramid adapter 3. Connect the test foot to the knee to be tested and connect the knee to the test jig 4. Install 3 sharpies into each hole and bend the knee up to 90° of flexion. 5. Each sharpie will provide a record of the toe, leg, heel trajectory. 6. Adjust the 5th bar and repeat the measurement on a new sheet of foam board. Adapter KNEE Test Foot Test Jig Foam Board
  43. 43. HD – KINEMATICS PROCESSING 1. Photograph each foam board (SONY DSLR on a tripod) using a longer focal length (70mm) to minimize geometric distortions. 2. Process the photos in Photoshop. (Straighten, crop, normalize) 3. Digitize the curves using ENGAUGE, a freeware curve digitizing programs (quite good too!) 4. Compute the data in Excel and calculate the centroid trajectory and toe clearance for each 5th bar adjustment. PROJECT IN PROGRESS The test jig and test foot have been built but no measurement and processing have been done yet.
  44. 44. HD - ADDENDUM
  45. 45. HD – ADDENDUM (2)
  46. 46. HD ADDENDUM(3)
  47. 47. HD ADDENDUM(4)
  48. 48. TEH-LIN KK950 “FIVE”-BAR POLYCENTRIC KNEE
  49. 49. KNEE KINEMATIC ANALYSIS The picture of the 4-bar polycentric prosthetic knee is calibrated in dimensions using Photoshop. The axis centered on the shank pylon is plotted, as well as the projection of the top pyramid adapter. (Scale 1:1) The coordinates of the joints of the 4-bar linkage are measured relative to A, defined as the knee axis of rotation. The angle of rotation of the knee is defined as the angle of the pylon from vertical . (Scale 1:1) x y D A 0 0 104.5 B 103.3 15.9 60.1 C 58.3 -24 45.8 D 12.6 -21.4 24.8 NOTE: The distance DC is adjustable 4-Bar linkage Geometry
  50. 50. -60 40 140 -100 0 100 200 300 400 500 600 KINEMATIC ANALYSIS KINEMATIC MODELING – Base of Foot (Nominal Leg Length) 540mm 200mm Shank Pylon Microsoft Excel
  51. 51. KINEMATIC ANALYSIS -60 40 140 -100 0 100 200 300 400 500 600 540mm 200mm KINEMATIC MODELING – TOES Shank Pylon Microsoft Excel
  52. 52. KINEMATIC ANALYSIS Some quick comments: This is entirely done in EXCEL using video screen capture with VLC media player. And YES! I did suffer and banged my head on the wall on a few occasions. However, I took the opportunity to dramatically enrich my vocabulary in trigonometric obscenities… And do not let me into the cluster f#@*#! of video codecs compatibles with just about nothing else…. 1) Between 0° and 40°, the toes do not clear the floor. 2) The gain in toe clearance provided by the polycentric design is very small. 3) The centroid of rotation between 0 and 13 degrees of flexion is BELOW the reference axis!!! However, over the same range, the centroid remains posterior to the reference axis providing added stability. Note: The motion of each leg component is calculated from classic trigonometry. The centroid is calculated as the center of a circle passing through three adjacent points of the trajectory.
  53. 53. KINEMATIC ANALYSIS -40 -20 0 20 40 0 5 10 15 20 25 30 35 40 45 50 Toe elevation Toe Circle Floor Flexion (°) Leg Vertical Length Variation as a Function of Knee Flexion Between 0 and 40°, the apparent vertical length of the leg exceeds the nominal length (i.e. The toes do not clear the floor). The blue curve represent the toes elevation relative to floor for the polycentric knee. The orange curve represent the toes elevation relative to floor for a single axis knee. The gain in toe-clearance from the polycentric knee is marginal. ToeElevationRelativetoFloor(mm)
  54. 54. KINEMATIC ANALYSIS 0 1 2 3 4 5 0 5 10 15 20 25 30 35 40 45 50 Difference Polycentric-Single Axis Floor Flexion (°)DifferencePolycentrictoSingleAxis(mm) The gain in toe clearance from the Polycentric Knee between 0° and 40° is less than 4mm. The maximum is 3.8mm at 33° of flexion. The green curve represents the difference in toe elevation relative to floor between the polycentric knee and a single axis knee. NEXT STEP? VALIDATE THESE RESULTS USING THE TEST JIG. NOT DONE YET.
  55. 55. HD - COMPONENTS • The only way to evaluate and compare the capabilities of commercial prosthetic components is to test them. • However, as I explain earlier the cost of these components is astronomical. So, what do we do? • Thanks to EBAY, used components are affordable. The current market value of used or even brand new prosthetic components is around 1 to 2 percent of the retail price. • YES, YOU READ WELL. 1% TO 2% OF THE RETAIL PRICE!! • Some examples below…. • TEH-LIN TGK5P00 KNEE MSRP $12,500 EBAY $175 1.4% • TEH-LIN KK150 KNEE (BRAND NEW) MRSP $15,100 EBAY $160 1.1% • MOBI OP4 KNEE (BRAND NEW) MSRP $11,000 EBAY $180 1.6%
  56. 56. HD - COMPONENTS • The prices on EBAY are low today because the demand is low. WHY? • Prosthetist do not and cannot use used components. Apparently for insurance reason. Sounds like a good excuse to me, as they make significant profit on the components. • The prosthetic market is quite unique as the customer (the amputee) doesn’t decide what components to use.
  57. 57. HD - COMPONENTS • The customer has a good medical insurance. The prosthetist will order the most expensive (not necessarily the most appropriate) components the insurance accept to pay. If the leg doesn’t work, it will eventually end up on EBAY. • The customer does not have medical insurance. The prosthetist will order the cheapest components. Nevertheless, the leg will still cost $20,000 (AK). The leg doesn’t work and the amputee will sell the components on EBAY. • The customer does not have medical insurance and doesn’t have $20,000. NO PROBLEMS! He can buy a pair of crutches at Walgreen for $20! Or, beg at the traffic light. In less than 15 years, he will have enough money for a leg… Unless he jumped under the 18-wheeler, of course….
  58. 58. HD - COMPONENTS • Most customer have complete faith in their prosthetist. Coping with the grief associated to recent limb loss and with no knowledge of prosthetic technology and practices, the new amputee relies completely on the person with the white lab coat talking with complicated words to put them back on two legs again. • The very large majority of prosthetists are honest and do the best they can for their patients. However, they are human, often overworked and with their own constraints. • To become a Board Certified O&P practitioner is a 2-year degree, not 7 like an M.D. Some are good and some are… “less good”.
  59. 59. HD - COMPONENTS • We have a large community of amputees in the US (1.7 millions). • 91% are lower limb amputees, most resulting from vascular disease (66%) and (20%) from trauma. Lower limb amputees from vascular diseases often suffer from additional conditions and may not be able to use their prosthetic leg. In addition, they have a high mortality rate. The leg components are sold on EBAY. Cause of Amputation in the US
  60. 60. HD - COMPONENTS • Most amputees rely completely on their prosthetists. • Prosthetists cannot use “used” components. • There are over 1.5 millions lower extremity amputees in the US. • Therefore, we have a market with a large supply and low demand. As a result…….
  61. 61. PROSTHETICS MY COLLECTION ORTHO EUROPE ULTIMATE KNEE: Single Axis – Adjustable hydraulic damping for flexion and extension – Adjustable weight activated stance control
  62. 62. PROSTHETICS MOBI-OP4: Single Axis – Adjustable pneumatic damping for flexion and extension – Weight activated stance control ENDOLITE: Single Axis – Adjustable hydraulic damping for flexion and extension – Weight activated stance control GRAPHLITE TCG-PS0: Polycentric 5-bar with adjustable centroid– Carbon fiber frame - Adjustable pneumatic damping for flexion and extension –stance flexion control ORTHO EUROPE: Single Axis – Adjustable hydraulic damping for flexion and extension – Weight activated stance control GRAPHLITE frame/ENDOLITE cylinder: Single Axis – Adjustable hydraulic damping for flexion and extension OTTO-BOCK 3R60: Polycentric– Adjustable hydraulic damping for flexion and extension – EBC for stance flexion ORTHO EUROPE: 2 Partial collection of prosthetic knees
  63. 63. PROSTHETICS Partial collection of prosthetic feet
  64. 64. PROSTHETICS Partial collection of 30mm prosthetic pylons (aluminum and carbon fiber) Carbon Fiber Carbon Fiber Carbon Fiber Carbon Fiber Pylons with integral Pyramid Adapter
  65. 65. Partial collection of various pyramid adapter/tube clamps. Mainly polished Titanium, some Stainless Steel and Aluminum. Adjustable Offset Adapter (Titanium) Adjustable Height Adapter (Titanium) (Aluminum) Angled Adapter for HD Prosthesis (Titanium) Male Adapter (Titanium)

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