Mountain bike modification for transtibial amputee
Chris & Mary Lake
Description
Collection
Title:
Mountain bike modification for transtibial amputee
Creator:
Chris & Mary Lake
Date:
7/25/1999
Text:
Hello,
One of my highly active transtibial patients recently started mountain
biking. When sitting, he can pedal with ease. But when he stands and
forcefully pedals (i.e. to go up an incline) - the transtibial side
locks. It appears that when he is centered over the pedals and the sound
side foot has reached the six o'clock position in the rotation, the
transtibial side cannot generate enough force to push the pedal down (as
it travels from the 11 o'clock to 12 o'clock position). Patient wears
an alpha liner and presents with about 115 - 120 degrees of flexion when
the transtibial side locks.
I do observe increased knee flexion in the standing vs. sitting position
on the bike. We have tried to extend the pedal in such a manner as to
move the transtibial side foot into a position in front of the pedal
(2-3 inches in front of the pedal axis. We used a long stirrup and
temporarily clamped this to the existing pedal. This helped (decreased
knee flexion observed) but did not seem like a long term solution
secondary to excessive movement of the pedal from the extended lever
arm. Still resistance is noted when the transtibial side nears the 12
o'clock position of the rotation, which ultimately leads to the
transtibial side locking. I prefer not to lower the posterior wall.
Can anyone provide me with some guidance to help this patient. Thank
you for your assistance.
Chris Lake, CPO
One of my highly active transtibial patients recently started mountain
biking. When sitting, he can pedal with ease. But when he stands and
forcefully pedals (i.e. to go up an incline) - the transtibial side
locks. It appears that when he is centered over the pedals and the sound
side foot has reached the six o'clock position in the rotation, the
transtibial side cannot generate enough force to push the pedal down (as
it travels from the 11 o'clock to 12 o'clock position). Patient wears
an alpha liner and presents with about 115 - 120 degrees of flexion when
the transtibial side locks.
I do observe increased knee flexion in the standing vs. sitting position
on the bike. We have tried to extend the pedal in such a manner as to
move the transtibial side foot into a position in front of the pedal
(2-3 inches in front of the pedal axis. We used a long stirrup and
temporarily clamped this to the existing pedal. This helped (decreased
knee flexion observed) but did not seem like a long term solution
secondary to excessive movement of the pedal from the extended lever
arm. Still resistance is noted when the transtibial side nears the 12
o'clock position of the rotation, which ultimately leads to the
transtibial side locking. I prefer not to lower the posterior wall.
Can anyone provide me with some guidance to help this patient. Thank
you for your assistance.
Chris Lake, CPO
Citation
Chris & Mary Lake, “Mountain bike modification for transtibial amputee,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 7, 2024, https://library.drfop.org/items/show/212107.
