4 ms·

These are statistics/math problems that 2 medical professionals I'm seeing are working on, not my own work. But they got me curious. FWIW I worked in "data sc

by chubot 5y ago

These are statistics/math problems that 2 medical professionals I'm seeing are working on, not my own work. But they got me curious. FWIW I worked in "data science" as a software engineer for many years, and did some machine learning, so I have some adjacent experience, but I could use help conceptualizing the problems. Does anyone know of any books or surveys about statistics and medicine, or specifically mechanics of the human body? - One therapist is taking measurements of say your arm motion and making inferences about the motion of other muscles. He does is very intuitively but wants to encode the knowledge in software. - The other one has an oral appliance that has a few parameters that need to be adjusted for different geometries of the mouth and airway. The problems aren't that well posed which is why I'm looking for pointers to related materials, rather than specific solutions (although any ideas are welcome). I appreciate replies here, and my e-mail is in my profile. I asked a former colleague with a Ph.D. and biostats and he didn't really know. Although I guess biostats is often specifically related to genetics? Or epidemiology? I guess the other thing this makes me think of is software for Invisalign or Lasik, etc. In fact I remember a former co-worker 10 years ago had actually worked on Lasik control software. If anyone has pointers to knowledge in these areas I'm interested.

ad404b8a372f2b9 5y ago
I can't help you conceptualize these specific problems but having worked on similar problems in the past I'd advise you to look into ordinary differential equations applied to those systems. They're used a lot for modelling in medical science and even if you're not interested in the dynamics of it they might lead you to the relevant literature for your problems and will address the parameters you're interested in and how they relate to each others.
jtolmar 5y ago
> One therapist is taking measurements of say your arm motion and making inferences about the motion of other muscles. This seems like a sequential Bayesian filtering problem. Probably high enough dimension that you should just use a particle filter. The big seminal background text in this area is Bishop: Pattern Recognition and Machine Learning. If the "motion of other muscles" is inferring pose, you could also look into what computer graphics calls inverse kinematics (a typical IK model has a number of dimensions that could fit into a particle filter). There's some more in-depth stuff in motion planning that actually takes into account muscle capability. But I wouldn't know where to find info on that, short of watching the last several years of Siggraph Technical Papers Trailers, grabbing all the motion planning ones, then reading everything they cite.
- chubot 5y ago
  Thanks, I will follow these references. I've heard of inverse kinematics but I think it's more focused on "modeling" than statistics/probability? That is, you would have to model each muscle? I think he is doing something that is more "invariant" across human variation? (strength, body dimensions, age, etc.) I'm not sure which is why my question was vague, but this is helpful.
  - jtolmar 5y ago
    Yeah, IK is about pose and motion modeling. But you can put any state+motion model inside sequential Bayes, and get the probability that the model is in a particular configuration out. Hard to know whether that's relevant without knowing what he's trying to predict though.
andrewnc 5y ago
It sounds vaguely related to "system identification"?
jpeloquin 5y ago
My research specialty is in orthopedic biomechanics. For the arm motion thing, it sounds like you might want inverse kinematics or inverse dynamics. Take a look at OpenSim: https://simtk.org/projects/opensim https://simtk.org/projects/opensim For the oral appliance adjustment, I'm not sure what your output measures of interest are. If they're mechanical maybe you want to do a sensitivity analysis using FEA. Maybe look at FEBio: https://febio.org/ https://febio.org/ As for books or surveys, biomechanics is huge topic so I'm not sure what to recommend without wasting your time. If you're still defining the problem, maybe run some searches on Pubmed with the "review" and "free full text" boxes checked, and browse the results until you find which sub-sub-topic is relevant to you? https://pubmed.ncbi.nlm.nih.gov/?term=biomechanics&filter=simsearch2.ffrft&filter=pubt.review https://pubmed.ncbi.nlm.nih.gov/?term=biomechanics&filter=si... If no one on the team knows statics, dynamics, and (if you're considering internal strain and stress) continuum mechanics, consider finding a mechanical engineer to help.
- chubot 5y ago
  Thank you for the references, I will follow these! I think the basic idea is that when you're doing physical therapy that targets certain muscles, you have to find the muscle(s) that are limiting the motion! This is not obvious because they all interact. Like if you have a back problem, you can try to exercise your back all you want, and that may not actually fix the problem. Because the real issue could be with your leg, which causes 16 hours a day of "bad" motion against your pelvis, which in turn messes up your back. All the muscles in the body are interlinked and they often compensate for each other. When people have a problem in one area, they compensate in other ways. So I have the same question as above: I think inverse kinematics is more about "modeling"? You would need to model every muscle, which is hard, and it is specific to a person? I think his intuition is partly based on a mental model, but it's also probablistic. I think the model has to capture the things that are "invariant" across humans (i.e. basic knowledge of anatomy), and the variation between humans is the probablistic part. It's also based on variation in your personal health history / observed behavior, e.g. how you walk, how often you're sitting at a computer, etc. So it does feel like an "inference" problem in that sense -- many factors/observations that result in multiple weighted guesses of the cause / effective therapies.

by chubot 5y ago

ad404b8a372f2b9 5y ago

I can't help you conceptualize these specific problems but having worked on similar problems in the past I'd advise you to look into ordinary differential equations applied to those systems. They're used a lot for modelling in medical science and even if you're not interested in the dynamics of it they might lead you to the relevant literature for your problems and will address the parameters you're interested in and how they relate to each others.

jtolmar 5y ago

> One therapist is taking measurements of say your arm motion and making inferences about the motion of other muscles. This seems like a sequential Bayesian filtering problem. Probably high enough dimension that you should just use a particle filter. The big seminal background text in this area is Bishop: Pattern Recognition and Machine Learning. If the "motion of other muscles" is inferring pose, you could also look into what computer graphics calls inverse kinematics (a typical IK model has a number of dimensions that could fit into a particle filter). There's some more in-depth stuff in motion planning that actually takes into account muscle capability. But I wouldn't know where to find info on that, short of watching the last several years of Siggraph Technical Papers Trailers, grabbing all the motion planning ones, then reading everything they cite.

chubot 5y ago
Thanks, I will follow these references. I've heard of inverse kinematics but I think it's more focused on "modeling" than statistics/probability? That is, you would have to model each muscle? I think he is doing something that is more "invariant" across human variation? (strength, body dimensions, age, etc.) I'm not sure which is why my question was vague, but this is helpful.
- jtolmar 5y ago
  Yeah, IK is about pose and motion modeling. But you can put any state+motion model inside sequential Bayes, and get the probability that the model is in a particular configuration out. Hard to know whether that's relevant without knowing what he's trying to predict though.

andrewnc 5y ago

It sounds vaguely related to "system identification"?

jpeloquin 5y ago

My research specialty is in orthopedic biomechanics. For the arm motion thing, it sounds like you might want inverse kinematics or inverse dynamics. Take a look at OpenSim: https://simtk.org/projects/opensim https://simtk.org/projects/opensim For the oral appliance adjustment, I'm not sure what your output measures of interest are. If they're mechanical maybe you want to do a sensitivity analysis using FEA. Maybe look at FEBio: https://febio.org/ https://febio.org/ As for books or surveys, biomechanics is huge topic so I'm not sure what to recommend without wasting your time. If you're still defining the problem, maybe run some searches on Pubmed with the "review" and "free full text" boxes checked, and browse the results until you find which sub-sub-topic is relevant to you? https://pubmed.ncbi.nlm.nih.gov/?term=biomechanics&filter=simsearch2.ffrft&filter=pubt.review https://pubmed.ncbi.nlm.nih.gov/?term=biomechanics&filter=si... If no one on the team knows statics, dynamics, and (if you're considering internal strain and stress) continuum mechanics, consider finding a mechanical engineer to help.

chubot 5y ago
Thank you for the references, I will follow these! I think the basic idea is that when you're doing physical therapy that targets certain muscles, you have to find the muscle(s) that are limiting the motion! This is not obvious because they all interact. Like if you have a back problem, you can try to exercise your back all you want, and that may not actually fix the problem. Because the real issue could be with your leg, which causes 16 hours a day of "bad" motion against your pelvis, which in turn messes up your back. All the muscles in the body are interlinked and they often compensate for each other. When people have a problem in one area, they compensate in other ways. So I have the same question as above: I think inverse kinematics is more about "modeling"? You would need to model every muscle, which is hard, and it is specific to a person? I think his intuition is partly based on a mental model, but it's also probablistic. I think the model has to capture the things that are "invariant" across humans (i.e. basic knowledge of anatomy), and the variation between humans is the probablistic part. It's also based on variation in your personal health history / observed behavior, e.g. how you walk, how often you're sitting at a computer, etc. So it does feel like an "inference" problem in that sense -- many factors/observations that result in multiple weighted guesses of the cause / effective therapies.