prosthetic alignment RESPONSES
Lauren Pedersen
Description
Collection
Title:
prosthetic alignment RESPONSES
Creator:
Lauren Pedersen
Date:
1/28/2020
Text:
I had a large number of you reply that you were interested in hearing the responses to my prosthetic bench alignment question. If more responses trickle in I will pass those along as well. Some things that I have adopted are:
- Outsetting foot to lateral patella for TTs since the patients I see typically fall into varus & if I do have to move the foot medial they accept that cosmetically more than having to move the foot out from center. For TF I often use ASIS through center of knee/foot in frontal plane for the same reason
- For TFs I prefer to draw hip flexion/adduction alignment references on the sock before casting since some of that may be lost when the patient holds their limb out to wrap the plaster bandage
- From our previously mentioned German trained summer student: for alignment of the components for a hemipelvectomy when you do not have ASIS and IT to find hip plate attachment point. Measure L5 spinous process to most lateral point of iliac crest on contralateral side, divide that number by 2 and add 1cm. Measure out that distance from spinous process on ipsilateral side for attachment plate placement. (ex from spine to right iliac crest is 14cm. Position plate 8cm to the left of spine)
Lauren Pedersen CP(c)
Static or bench alignment or initial set-up is your best estimation of where to need to be, or where you'll end up after standing and walking your patient. Look at your patient. Stand them in the bars if possible. Note the angles of the limbs, contractures present. Try to Visualize the weightline. Portable handheld floor level can be used but not necessary. If your patient can't stand, stand over them while they're prone In ed or on a table. Align the limbs in frontal plane, note contractures in sagital plane. Again try to visualize and imagine your weight line and what would happen at each segment as patient bears weight through your initial set up of socket and components with foot. If your patient has Tight hip flexors and assumes a forward bending posture at the torso While standing in the bars- then note this -maybe take a picture of this and try to copy this into your initial set up. The whole idea is to try and create an initial prosthetic set up that's is very close to where you would end up after they walk so you don't end up removing your prosthesis and test components multiple times and exhausting your patient in an initial set up procedure . the goal is to get them walking as soon as possible. all of this can be accomplished by examining a patient lying down on a Mat visually from multiple angles and from having a patient stand in the parallel bars and examining the patient's weight line from torso through the ground. again if you spent a lot of time on trying to nail the perfect initial set up you will not have time working with your patient sometimes it is best to set up your prosthesis quickly- be sure your height is correct stand your patient and make adjustments as necessary in a standing assessment. There are several tools including laser posterior handheld laser machines those are great but look at your patient visualize what will happen i.e. specific moments and torques at segments. Hope this is helpful.
i have always maintained that the industry does not pay enough attention to the bench alignment, and the way they make the legs today makes it even harder if not almost impossible to set a proper bench alignment. that is why i started making my own A/K prosthetic legs years ago and have made hundreds of scientifically recorded alignments and now make and hold all my socket angles and alignments + or - two degrees.
i am not a certified limb maker but have always been involved in engineering and design and now make all my sockets so they fit me with just the right amount of firmness that is comfortable for me.
i have gone to many limb makers had legs made but always ended up with problems. when asked what i do that different then what they do i say: i do everything you do except when its not right i redo it and redo it till it is right, and i know that would be to expensive for all to do. but now i have it down to a precise way of keeping the bench alignment and socket angles always the same for me. all my legs are the same for me and i can switch them and walk away on any one of them with no problems.
So in summary the Bench alignment and Socket angles related with the Knee Center need more attention than most makers give. this also includes the AD and the Flexion which i could tell you how often these have been so bad because they go by sight and don't scientifically measure for this.
any way i could go on and on but just thought you might find this of interest.
Are use a classic plumbob on a string visually referencing the center of the socket.
For AP I drop that line through the knee and foot according to the manufacturer specifications.
ML alignment is fairly patient specific.
The truth is I've been doing it so long that my intuition generally gets me within a half a screw turn of where I need to be.
Every patient is different. There is no fits all formula in my experience. Ad/Ab duction is the main elusive adjustment along with linear movement of course. The purpose for Walking/ dynamic check sockets is to wash out the patient specific anomalies. If there was pattern of consistent this fits all I would have slept better on a nightly basis. I have a feeling that the term bench alignment was coined for technicians that never laid eyes on the patient or a practitioner that never took note of the patients specific potential gait. The contra lateral side contributes (dare I say) a third of this bench alignment to be made. I guess I could have just said that the cascade of factors that determine bench alignment make it apparent that a good assessment of the patients posture is the key to predicting the alignment.
I set everything up using mfg guidelines as long as it is not at odds with fundamental alignment concepts. The packing materials/ instructions that come with the components are important.
Good question you put forth on the listserve. I have found the following works well for Tf bench/static alignments
* First establish lateral wall midpoint. I do this by averagjng the sitting and standing A-P measurements and marking that point on the medial wall as measured from the interior anterior socket wall. Then with the socket held in the correct line of progression, transfer that mark to the lateral wall. It may or may not bisect the lateral socket wall.
* Establish the anterior wall midpoint. I do this by measuring the M-L distance inside the socket using the two marks above as a reference. It may or may not bisect the anterior socket wall.
* Establish the knee and foot alignment (using your knee center measurement) as per the manufacturer's recommendation. In the sagittal plane, Otto Bock gives you more than 1 cm to play with especially with single axis and SACH feet. Ossur is generally more strict especially with the Rheo. The Mauch is a bit better. The Total Knee offers the greatest alignment potential given the stance flexion bumpers and shims. For all manufacturers, unless I know the patient's alignment, I will align the set screws (foot, tube, socket adaptor) in the frontal plane to establish knee and foot rotation.
* Establish the medial socket wall height (IT to floor or perineum to floor measurement). With Otto Bock components, your socket has to be placed more forward in the sagittal plane given their mechanical alignment. Using the lateral wall midpoint mark as my reference - the weight line should pass between the knee and foot as recommended (all knees and feet). If you are having problems with the socket adaptor, you can fudge a bit by increasing or decreasing the weight line position since Bock recommends the 5mm heel lift for bench alignment. With Ossur, for Rheo, the weight line should pass through the knee center. For Mauch, slightly behind. For Total Knee, well it just depends on many factors but generally it will pass slightly anterior to the midpoint of the pivot axis. The VGK is like the Mauch, slightly behind the knee center.
* For all manufacturers, I have never bisected the socket in the frontal plane even for through knee/KD amputees. The socket should be inset using the aforementioned anterior wall midpoint mark. The distance depends upon a host of factors like ab/adduction angle, limb length, muscle strength, hip mobility, etc. For medium length limbs, with no unusual issues, 1cm is a good starting point. As the patient learns to walk, you may end up reducing the inset for the final socket alignment.
I have always liked the Hosmer jig for bench alignments although it can sometimes present challenges with knee and foot rotation given its simplistic design. I do not use a shoe when aligning. I put crepe under the heel to match the heel height of the foot (+ 5mm for Otto Bock). I use a laser for the frontal plane and a plumb bob for the sagittal plane alignments. I am not a fan of the laser posture although it is a good marketing tool.
I have researched this topic and tried the different alignment methods with varying degrees of success. This one sort of evolved over time and very rarely requires changes. Some of the Ossur feet in smaller and larger sizes do not align using the posterior third method. Always measure the foot cover and mark the third position. It can be very different than what is indicated by Ossur inside the foot covers. For every Re-Flex model regardless of foot size, I have had to move the alignment line more posterior than the 1/3 and more inset than say a Vari-Flex or Assure. This is also true to Tt alignments.
A trick somewhat related to alignment: on a TF cast If I am happy with the adduction I always reduce the posterior lateral wall in at least as far as the distal femur to avoid a gapping lateral wall
This e-mail may contain confidential and/or privileged information for the sole use of the intended recipient. Any review or distribution by anyone other than the person for whom it was originally intended is strictly prohibited. If you have received this e-mail in error, please contact the sender and delete all copies. Opinions, conclusions or other information contained in this e-mail may not be that of the organization.
- Outsetting foot to lateral patella for TTs since the patients I see typically fall into varus & if I do have to move the foot medial they accept that cosmetically more than having to move the foot out from center. For TF I often use ASIS through center of knee/foot in frontal plane for the same reason
- For TFs I prefer to draw hip flexion/adduction alignment references on the sock before casting since some of that may be lost when the patient holds their limb out to wrap the plaster bandage
- From our previously mentioned German trained summer student: for alignment of the components for a hemipelvectomy when you do not have ASIS and IT to find hip plate attachment point. Measure L5 spinous process to most lateral point of iliac crest on contralateral side, divide that number by 2 and add 1cm. Measure out that distance from spinous process on ipsilateral side for attachment plate placement. (ex from spine to right iliac crest is 14cm. Position plate 8cm to the left of spine)
Lauren Pedersen CP(c)
Static or bench alignment or initial set-up is your best estimation of where to need to be, or where you'll end up after standing and walking your patient. Look at your patient. Stand them in the bars if possible. Note the angles of the limbs, contractures present. Try to Visualize the weightline. Portable handheld floor level can be used but not necessary. If your patient can't stand, stand over them while they're prone In ed or on a table. Align the limbs in frontal plane, note contractures in sagital plane. Again try to visualize and imagine your weight line and what would happen at each segment as patient bears weight through your initial set up of socket and components with foot. If your patient has Tight hip flexors and assumes a forward bending posture at the torso While standing in the bars- then note this -maybe take a picture of this and try to copy this into your initial set up. The whole idea is to try and create an initial prosthetic set up that's is very close to where you would end up after they walk so you don't end up removing your prosthesis and test components multiple times and exhausting your patient in an initial set up procedure . the goal is to get them walking as soon as possible. all of this can be accomplished by examining a patient lying down on a Mat visually from multiple angles and from having a patient stand in the parallel bars and examining the patient's weight line from torso through the ground. again if you spent a lot of time on trying to nail the perfect initial set up you will not have time working with your patient sometimes it is best to set up your prosthesis quickly- be sure your height is correct stand your patient and make adjustments as necessary in a standing assessment. There are several tools including laser posterior handheld laser machines those are great but look at your patient visualize what will happen i.e. specific moments and torques at segments. Hope this is helpful.
i have always maintained that the industry does not pay enough attention to the bench alignment, and the way they make the legs today makes it even harder if not almost impossible to set a proper bench alignment. that is why i started making my own A/K prosthetic legs years ago and have made hundreds of scientifically recorded alignments and now make and hold all my socket angles and alignments + or - two degrees.
i am not a certified limb maker but have always been involved in engineering and design and now make all my sockets so they fit me with just the right amount of firmness that is comfortable for me.
i have gone to many limb makers had legs made but always ended up with problems. when asked what i do that different then what they do i say: i do everything you do except when its not right i redo it and redo it till it is right, and i know that would be to expensive for all to do. but now i have it down to a precise way of keeping the bench alignment and socket angles always the same for me. all my legs are the same for me and i can switch them and walk away on any one of them with no problems.
So in summary the Bench alignment and Socket angles related with the Knee Center need more attention than most makers give. this also includes the AD and the Flexion which i could tell you how often these have been so bad because they go by sight and don't scientifically measure for this.
any way i could go on and on but just thought you might find this of interest.
Are use a classic plumbob on a string visually referencing the center of the socket.
For AP I drop that line through the knee and foot according to the manufacturer specifications.
ML alignment is fairly patient specific.
The truth is I've been doing it so long that my intuition generally gets me within a half a screw turn of where I need to be.
Every patient is different. There is no fits all formula in my experience. Ad/Ab duction is the main elusive adjustment along with linear movement of course. The purpose for Walking/ dynamic check sockets is to wash out the patient specific anomalies. If there was pattern of consistent this fits all I would have slept better on a nightly basis. I have a feeling that the term bench alignment was coined for technicians that never laid eyes on the patient or a practitioner that never took note of the patients specific potential gait. The contra lateral side contributes (dare I say) a third of this bench alignment to be made. I guess I could have just said that the cascade of factors that determine bench alignment make it apparent that a good assessment of the patients posture is the key to predicting the alignment.
I set everything up using mfg guidelines as long as it is not at odds with fundamental alignment concepts. The packing materials/ instructions that come with the components are important.
Good question you put forth on the listserve. I have found the following works well for Tf bench/static alignments
* First establish lateral wall midpoint. I do this by averagjng the sitting and standing A-P measurements and marking that point on the medial wall as measured from the interior anterior socket wall. Then with the socket held in the correct line of progression, transfer that mark to the lateral wall. It may or may not bisect the lateral socket wall.
* Establish the anterior wall midpoint. I do this by measuring the M-L distance inside the socket using the two marks above as a reference. It may or may not bisect the anterior socket wall.
* Establish the knee and foot alignment (using your knee center measurement) as per the manufacturer's recommendation. In the sagittal plane, Otto Bock gives you more than 1 cm to play with especially with single axis and SACH feet. Ossur is generally more strict especially with the Rheo. The Mauch is a bit better. The Total Knee offers the greatest alignment potential given the stance flexion bumpers and shims. For all manufacturers, unless I know the patient's alignment, I will align the set screws (foot, tube, socket adaptor) in the frontal plane to establish knee and foot rotation.
* Establish the medial socket wall height (IT to floor or perineum to floor measurement). With Otto Bock components, your socket has to be placed more forward in the sagittal plane given their mechanical alignment. Using the lateral wall midpoint mark as my reference - the weight line should pass between the knee and foot as recommended (all knees and feet). If you are having problems with the socket adaptor, you can fudge a bit by increasing or decreasing the weight line position since Bock recommends the 5mm heel lift for bench alignment. With Ossur, for Rheo, the weight line should pass through the knee center. For Mauch, slightly behind. For Total Knee, well it just depends on many factors but generally it will pass slightly anterior to the midpoint of the pivot axis. The VGK is like the Mauch, slightly behind the knee center.
* For all manufacturers, I have never bisected the socket in the frontal plane even for through knee/KD amputees. The socket should be inset using the aforementioned anterior wall midpoint mark. The distance depends upon a host of factors like ab/adduction angle, limb length, muscle strength, hip mobility, etc. For medium length limbs, with no unusual issues, 1cm is a good starting point. As the patient learns to walk, you may end up reducing the inset for the final socket alignment.
I have always liked the Hosmer jig for bench alignments although it can sometimes present challenges with knee and foot rotation given its simplistic design. I do not use a shoe when aligning. I put crepe under the heel to match the heel height of the foot (+ 5mm for Otto Bock). I use a laser for the frontal plane and a plumb bob for the sagittal plane alignments. I am not a fan of the laser posture although it is a good marketing tool.
I have researched this topic and tried the different alignment methods with varying degrees of success. This one sort of evolved over time and very rarely requires changes. Some of the Ossur feet in smaller and larger sizes do not align using the posterior third method. Always measure the foot cover and mark the third position. It can be very different than what is indicated by Ossur inside the foot covers. For every Re-Flex model regardless of foot size, I have had to move the alignment line more posterior than the 1/3 and more inset than say a Vari-Flex or Assure. This is also true to Tt alignments.
A trick somewhat related to alignment: on a TF cast If I am happy with the adduction I always reduce the posterior lateral wall in at least as far as the distal femur to avoid a gapping lateral wall
This e-mail may contain confidential and/or privileged information for the sole use of the intended recipient. Any review or distribution by anyone other than the person for whom it was originally intended is strictly prohibited. If you have received this e-mail in error, please contact the sender and delete all copies. Opinions, conclusions or other information contained in this e-mail may not be that of the organization.
Citation
Lauren Pedersen, “prosthetic alignment RESPONSES,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 23, 2024, https://library.drfop.org/items/show/209838.
