Responses to LASAR Posture
Gregory M. Straub, CPO
Description
Collection
Title:
Responses to LASAR Posture
Creator:
Gregory M. Straub, CPO
Date:
1/13/2006
Text:
The original post was just before the holidays.Here are the resposes I received. Thanks to all that responded. More responses would be appreciated for further insight.
We use the LASAR posture for teaching purposes at Georgia Tech Master of
Science in Prosthetics and Orthotics program. Use of the device has been
integrated with our courses in Kinesiology and Biomechanics as well as
Lower Limb Orthotics, Spinal Orthotics and Trans Tibial and well as
Trans Femoral Prosthetics courses. We find it to be more dynamic than
simply using a plumb bob although the plumb bob has its uses too as a
low cost and effective tool to estimate the line of gravity. We have
found use of the LASAR posture device effective in demonstrating to
students the alignment of the lower limb joints in relation to changes
in stance phase.
We are getting the sales pitch and currently considering this purchase too. Great idea posting this on the listserv, BRILLIANT. I'll look forward to hearing the responses you get.
J'ai personnellement utilisé le LASAR POSTUR. Cet appareil contrairement à
ce qu' ottobock prétend il ne donne qu' une droite passant par le centre de
gravité de la zone d'appui sur le LASAR. Il est difficile d'obtenir une
droite passant par la ligne d'alignement de la prothèse. Par contre c'est
une excellente bascule et de plus on peut l'utiliser pour étudier la
répartition d'appui sur les deux jambes.(équilibre)
This equipment is useful to align a lower limb (L.L) modular prosthesis in the lateral plane. Every L.L. prosthesis is a passive device, that is to say it receives energy from the body of patient to work properly (this also for electronically controlled joints).Due to this introduction, it is really important the load line location with respect to the joint centers (always on the lateral plane) such as knee or ankle joint for a transfemoral prosthesis.LASAR traces the real (objective) load line on the prosthetic limb of your patient so that you can verify and eventually adjust the device alignment (4 screws modules) according to the joints manuals. This helps you to better fit a prosthesis and I'll make an example.If you are using a hydraulic knee (with a unit that controls both stance and swing phase) and, by means of LASAR posture, discover the load line passes in front of the knee center (patient is standing), the joint will not work correctly. If you observe it during motion (stance phase), you'll realize an hyper extension from the heel contact to the toe off. This stretches the hydraulic rod and in a short period could damage the knee frame. All the time you observe hyper extension during stance the hyd. unit doesn't work at all. (hyper extension is just limited by rod tension and knee extension stops). In this case a cheaper joint could be fitted (i.e. automatic brake knees).Remind that an excessive extension torque during stance involves excessive contact forces between stump and socket. I saw several prostheses fitted with C-leg too working in this way!LASAR is a good and simple method to avoid that. There is a limit to this method: if a bad mistake has been done to locate the proximal connector (i.e. A.K.) on the socket (3 prong conn. or wooden att. block) could be difficult to remediate adjusting the 4 screws modules (on the 3 prong connector, clamp adapter for tube, tube adapter). In this case you should use an alignment device to correct the problem and LASAR for the feedback, in order to evaluate the functional response.Finally there are some cases you are adjusting to find a right alignment (i.e. shifting back the load line), but LASAR points out always the same spatial position (distance) both for the load line and the joint centre (i.e. knee). This means your patient (usually this happens with amputees used to walk with no stance control knees, so that they do want to feel the device in full extension for their safety) is extending the hip muscles. Only your experience or a gait analysis lab can help you in this case.On the other hand if you're fitting an A.K. prosthesis with a hydraulic knee it could be advisable (according to the patient characteristics) to control the knee flexion (stance phase) using both the hyd. unit and the hip muscles: this helps the patient to tone up the stump during walking. In this case also a gait analysis lab is needed for feedback.
Biggest waste of money I have ever made!
We were aligning C-legs without it for the first couple. It was taking a lot of trial and error to dial in the positioning a-p of the socket for optimal alignment. When ours arrived, I was aligning a knee disarticulation, and had already gunked and broken loose the socket a couple of times. Put him on the lasar, showed how much needed shifting, and it worked out great. It really has helped for C-leg aligning. Have seen/heard that it can be applied to other feet and even bk's to speed alignment. Haven't taken the extra time (which it probably would save) to apply it other than C-legs
We use the LASAR posture for teaching purposes at Georgia Tech Master of
Science in Prosthetics and Orthotics program. Use of the device has been
integrated with our courses in Kinesiology and Biomechanics as well as
Lower Limb Orthotics, Spinal Orthotics and Trans Tibial and well as
Trans Femoral Prosthetics courses. We find it to be more dynamic than
simply using a plumb bob although the plumb bob has its uses too as a
low cost and effective tool to estimate the line of gravity. We have
found use of the LASAR posture device effective in demonstrating to
students the alignment of the lower limb joints in relation to changes
in stance phase.
We are getting the sales pitch and currently considering this purchase too. Great idea posting this on the listserv, BRILLIANT. I'll look forward to hearing the responses you get.
J'ai personnellement utilisé le LASAR POSTUR. Cet appareil contrairement à
ce qu' ottobock prétend il ne donne qu' une droite passant par le centre de
gravité de la zone d'appui sur le LASAR. Il est difficile d'obtenir une
droite passant par la ligne d'alignement de la prothèse. Par contre c'est
une excellente bascule et de plus on peut l'utiliser pour étudier la
répartition d'appui sur les deux jambes.(équilibre)
This equipment is useful to align a lower limb (L.L) modular prosthesis in the lateral plane. Every L.L. prosthesis is a passive device, that is to say it receives energy from the body of patient to work properly (this also for electronically controlled joints).Due to this introduction, it is really important the load line location with respect to the joint centers (always on the lateral plane) such as knee or ankle joint for a transfemoral prosthesis.LASAR traces the real (objective) load line on the prosthetic limb of your patient so that you can verify and eventually adjust the device alignment (4 screws modules) according to the joints manuals. This helps you to better fit a prosthesis and I'll make an example.If you are using a hydraulic knee (with a unit that controls both stance and swing phase) and, by means of LASAR posture, discover the load line passes in front of the knee center (patient is standing), the joint will not work correctly. If you observe it during motion (stance phase), you'll realize an hyper extension from the heel contact to the toe off. This stretches the hydraulic rod and in a short period could damage the knee frame. All the time you observe hyper extension during stance the hyd. unit doesn't work at all. (hyper extension is just limited by rod tension and knee extension stops). In this case a cheaper joint could be fitted (i.e. automatic brake knees).Remind that an excessive extension torque during stance involves excessive contact forces between stump and socket. I saw several prostheses fitted with C-leg too working in this way!LASAR is a good and simple method to avoid that. There is a limit to this method: if a bad mistake has been done to locate the proximal connector (i.e. A.K.) on the socket (3 prong conn. or wooden att. block) could be difficult to remediate adjusting the 4 screws modules (on the 3 prong connector, clamp adapter for tube, tube adapter). In this case you should use an alignment device to correct the problem and LASAR for the feedback, in order to evaluate the functional response.Finally there are some cases you are adjusting to find a right alignment (i.e. shifting back the load line), but LASAR points out always the same spatial position (distance) both for the load line and the joint centre (i.e. knee). This means your patient (usually this happens with amputees used to walk with no stance control knees, so that they do want to feel the device in full extension for their safety) is extending the hip muscles. Only your experience or a gait analysis lab can help you in this case.On the other hand if you're fitting an A.K. prosthesis with a hydraulic knee it could be advisable (according to the patient characteristics) to control the knee flexion (stance phase) using both the hyd. unit and the hip muscles: this helps the patient to tone up the stump during walking. In this case also a gait analysis lab is needed for feedback.
Biggest waste of money I have ever made!
We were aligning C-legs without it for the first couple. It was taking a lot of trial and error to dial in the positioning a-p of the socket for optimal alignment. When ours arrived, I was aligning a knee disarticulation, and had already gunked and broken loose the socket a couple of times. Put him on the lasar, showed how much needed shifting, and it worked out great. It really has helped for C-leg aligning. Have seen/heard that it can be applied to other feet and even bk's to speed alignment. Haven't taken the extra time (which it probably would save) to apply it other than C-legs
Citation
Gregory M. Straub, CPO, “Responses to LASAR Posture,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 1, 2024, https://library.drfop.org/items/show/226062.
