Response to cycling prosthesis problem
Lee Childers
Description
Collection
Title:
Response to cycling prosthesis problem
Creator:
Lee Childers
Date:
11/13/2008
Text:
Sorry to reply to the entire list but I was forwarded this email and did not know the reply address.
My research at Georgia Tech has been dedicated to the biomechanics of cyclists with and without amputations over the past three years. There are many details that may help me make the best recommendation and I encourage you to contact me directly at <Email Address Redacted>
A bi-lateral TT/TF is a complicated case to begin with. The closed kinematic chain aspect of the cycling task also adds it own challenges. It sounds like a lot of your problem will be related to the geometry of both the bike, the prostheses and the person. Trying to find the best way to optimize all three at once is always a challenge. I'll be more than happy to offer you any insight that may help this patient (or any other patients) get into cycling. Side note, We are also starting a new study into the biomechanics of cyclists with amputations so if anyone has a patient out there that cycles and would like to come to Atlanta for a bit, I'd love to talk with them as well.
Below are several questions that can better help me help you.
Do you have the resources to make cycling specific legs for both sides?
What is the patient's current seat height? Best to measure from the top of the pedal to the top of the saddle at the widest point. I usually put a straight edge or level to make things eaiser. How does that compare with a measurement from the floor to greater trochanter?
What make/model and frame size are you working with? What are the crank arm lengths? Is the bike still in relatively stock form or have you changed things (especially the handlebar position)? Is this a more standard road bike with drop bars or a more triathlon style with aero bars? When you say the tuck position, do you mean a when he holds the handlebar in the lower portion of the drop bars? This is also called riding in the drops. Sometimes, there's different slang for the same thing and I just want to be clear.
What sort of pedal system is he using so keep his feet on the pedals? What sort of feet, if any, are used for cycling (our orignial study that was presented at ISPO, AOPA found stiff foot = better)? If feet are being used, are they in a cycling shoe? How is the foot positioned relative to the pedal spindle? That is the long way of saying where is the cycling cleat?
The length of each lower limb segment also comes into play here. What is the distance from the cycling cleat to the knee center? From the knee center to the greater trochanter? Measurements for each limb would be needed. The main purpose for all of this is that I have created software that can calculate the optimal prosthetic length, alignment, and saddle position if I know geometry of the whole lower limb. I will probably also need measurements from greater trochanter to approximate center of the humeral head (measured standing), the humeral head to elbow center and elbow center to base of the little finger. A saggital plane photograph of him on the bike would also be very helpful.
Alright, that's a long list of questions but its difficult to make any well-thought out recommendation without knowing all the facts. Hope to hear back from you soon and I'll be happy to help any way I can.
Lee Childers EIT MSPO
PhD student in Applied Physiology, specialty in P&O research
Georgia Institute of Technology
<Email Address Redacted>
770-355-4184
Dear List,
I have a 24 y.o. male Iraqi veteran amputee that is extremely active and
wants to ride a standard racing bike. The patient has a left
transtibial
amputation and a right transfemoral amputation. The problem I am having
is
with the transfemoral side. The patient's current ambulatory/running
prosthesis is ischial containment with flexible inner/external frame.
The
patient's limb is suspended with a seal-in liner and Coyote summit lock.
The problem I am experiencing is that the patient goes into 120-130
degrees
of flexion at the hip when he is in his tuck position in the bike and
the
socket is breaking suction in turn pulling on the and summit lock to the
point that the liner almost wants to come off. The patient's residual
limb
length is only 7 1/2 . I have duplicated his everyday prosthesis and
cut
it down to be almost a plug fit. The medial wall was lowered to
accommodate
the bicycle seat and I brought the anterior trim line very low to not
interfere when the patient ranges into full hip flexion. The pedal
lengths
and seat height seem appropriate. Any suggestions would be greatly
appreciated. Thanks.
Trevor Townsend C.P.O
Bakersfield, CA
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If you have a problem unsubscribing,or have other
questions, send e-mail to the moderator
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OANDP-L is a forum for the discussion of topics
related to Orthotics and Prosthetics.
Public commercial postings are forbidden. Responses to inquiries
should not be sent to the entire oandp-l list. Professional credentials
or affiliations should be used in all communications.
My research at Georgia Tech has been dedicated to the biomechanics of cyclists with and without amputations over the past three years. There are many details that may help me make the best recommendation and I encourage you to contact me directly at <Email Address Redacted>
A bi-lateral TT/TF is a complicated case to begin with. The closed kinematic chain aspect of the cycling task also adds it own challenges. It sounds like a lot of your problem will be related to the geometry of both the bike, the prostheses and the person. Trying to find the best way to optimize all three at once is always a challenge. I'll be more than happy to offer you any insight that may help this patient (or any other patients) get into cycling. Side note, We are also starting a new study into the biomechanics of cyclists with amputations so if anyone has a patient out there that cycles and would like to come to Atlanta for a bit, I'd love to talk with them as well.
Below are several questions that can better help me help you.
Do you have the resources to make cycling specific legs for both sides?
What is the patient's current seat height? Best to measure from the top of the pedal to the top of the saddle at the widest point. I usually put a straight edge or level to make things eaiser. How does that compare with a measurement from the floor to greater trochanter?
What make/model and frame size are you working with? What are the crank arm lengths? Is the bike still in relatively stock form or have you changed things (especially the handlebar position)? Is this a more standard road bike with drop bars or a more triathlon style with aero bars? When you say the tuck position, do you mean a when he holds the handlebar in the lower portion of the drop bars? This is also called riding in the drops. Sometimes, there's different slang for the same thing and I just want to be clear.
What sort of pedal system is he using so keep his feet on the pedals? What sort of feet, if any, are used for cycling (our orignial study that was presented at ISPO, AOPA found stiff foot = better)? If feet are being used, are they in a cycling shoe? How is the foot positioned relative to the pedal spindle? That is the long way of saying where is the cycling cleat?
The length of each lower limb segment also comes into play here. What is the distance from the cycling cleat to the knee center? From the knee center to the greater trochanter? Measurements for each limb would be needed. The main purpose for all of this is that I have created software that can calculate the optimal prosthetic length, alignment, and saddle position if I know geometry of the whole lower limb. I will probably also need measurements from greater trochanter to approximate center of the humeral head (measured standing), the humeral head to elbow center and elbow center to base of the little finger. A saggital plane photograph of him on the bike would also be very helpful.
Alright, that's a long list of questions but its difficult to make any well-thought out recommendation without knowing all the facts. Hope to hear back from you soon and I'll be happy to help any way I can.
Lee Childers EIT MSPO
PhD student in Applied Physiology, specialty in P&O research
Georgia Institute of Technology
<Email Address Redacted>
770-355-4184
Dear List,
I have a 24 y.o. male Iraqi veteran amputee that is extremely active and
wants to ride a standard racing bike. The patient has a left
transtibial
amputation and a right transfemoral amputation. The problem I am having
is
with the transfemoral side. The patient's current ambulatory/running
prosthesis is ischial containment with flexible inner/external frame.
The
patient's limb is suspended with a seal-in liner and Coyote summit lock.
The problem I am experiencing is that the patient goes into 120-130
degrees
of flexion at the hip when he is in his tuck position in the bike and
the
socket is breaking suction in turn pulling on the and summit lock to the
point that the liner almost wants to come off. The patient's residual
limb
length is only 7 1/2 . I have duplicated his everyday prosthesis and
cut
it down to be almost a plug fit. The medial wall was lowered to
accommodate
the bicycle seat and I brought the anterior trim line very low to not
interfere when the patient ranges into full hip flexion. The pedal
lengths
and seat height seem appropriate. Any suggestions would be greatly
appreciated. Thanks.
Trevor Townsend C.P.O
Bakersfield, CA
********************
To unsubscribe, send a message to: <Email Address Redacted> with
the words UNSUB OANDP-L in the body of the
message.
If you have a problem unsubscribing,or have other
questions, send e-mail to the moderator
Paul E. Prusakowski,CPO at <Email Address Redacted>
OANDP-L is a forum for the discussion of topics
related to Orthotics and Prosthetics.
Public commercial postings are forbidden. Responses to inquiries
should not be sent to the entire oandp-l list. Professional credentials
or affiliations should be used in all communications.
Citation
Lee Childers, “Response to cycling prosthesis problem,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 2, 2024, https://library.drfop.org/items/show/229830.
