Fryette's Principles

by Sheldon C. Yao, DO

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    00:01 Harrison Fryette was a DO that studied the relationship of the thoracic spine and the lumbar spine and he came up with several principles relating to the, based on the anatomy of the spine, the motions that is associated with it.

    00:16 And so a lot of his principles are utilized when we're diagnosing somatic dysfunctions of the spine.

    00:23 So, Dr. Fryette's 1st principle is that when we have side-bending introduced to the spine, in a neutral spine, meaning that there is no flexion or extension component, you're gonna have the bodies of the vertebrae rotate to the side of the convexity.

    00:40 So side-bending and rotation occur in opposite directions.

    00:44 So If I'm sidebending my body to the right, my vertebra will rotate to the left due to anatomical connections between the muscles and the ligaments.

    00:54 This applies again to group curves, meaning, a group curve is defined by having three or more vertebral bodies.

    01:01 And also neutral curves, meaning that there is not a flexion or extension component.

    01:06 So this is, like I said before, considered type I somatic dysfunctions.

    01:11 Fryette's 2nd principle applies to a non-neutral spine.

    01:15 What a non-neutral spine means is that it is usually a single segment that has associated freedom with flexion or extension.

    01:24 So, what happens in a type II dysfunction is that you have rotation to the side of the concavity.

    01:30 That means that rotation and sidebending are coupled to the same direction.

    01:35 Again, it applies to a single unit and so this is what we call a type II somatic dysfunction when you have side-bending rotation to the same direction.

    01:46 Another observation that he made is that in his 3rd principle, he talks about if you initiate a motion of the vertebra in one plane of motion, you will modify or usually limit the motion of the segment in the other planes.

    02:02 So here, we're reviewing the principle of side-bending and rotation being coupled.

    02:06 So if I have a type I dysfunction, the neutral spine will display sidebending rotation in opposite directions.

    02:14 In a type II dysfunction, side-bending rotation will be coupled to the same side.

    02:18 This is because a lot of times that dysfunction is due to a restriction of a facet on one side.

    02:26 Fryette's 3rd principle discusses motion of vertebra in one plane will influence motion in the other.

    02:32 So if you think about it, if I try to just side bend to the side, I have a certain freedom in motion.

    02:39 If I add rotation and then try to side-bend to the side, now I'm more limited with how much I could rotate and side-bend.

    02:46 So, anytime you have more than one movement, it will influence motion in the others.

    02:53 So, how does this play into diagnosing somatic dysfunctions? So, taking a closer look at Fryette's first principle, if we have a neutral spine, side-bending rotation are gonna be opposite.

    03:05 So in a type I group curve, this is what occurs when you have tight muscles on one side of the spine or sometimes there may be a sort of asymmetry in the pelvis, a leg length which cause a curve to occur in the spine.

    03:21 So let's take a look at type I dysfunctions.

    03:25 Here's an example, we have a T5 to T9 neutral side bend right, rotated left somatic dysfunction.

    03:32 So here, we know that it's neutral, side bent right, rotated left.

    03:36 It's a neutral curve and so it has to be a group dysfunction.

    03:41 Again, a type I dysfunction has to be at least three or more segments.

    03:44 So here, we have T5 to T9 which meets that criteria.

    03:48 And what we usually find on palpation is that from T5 to 9 here, we have the transverse process on the left, more posterior.

    03:58 So we have asymmetry here, there's a freedom of motion.

    04:01 Those transverse processes like to rotate left, so as we palpate from T5 to T9, we have transverse processes rotated left.

    04:11 If I check in flexion and extension, the segment does not change much.

    04:15 That's what defines a neutral curve.

    04:18 And so, we have T5 to (9) neutral, rotated left and following Fryette's principle no. 1, we now assume that it's gonna be side bend right because that's the only way the spine moves anatomically So, these type of neutral dysfunctions may be adaption such as in scoliosis.

    04:38 We have tight muscles and that could pull the curve and cause it to side bend to a certain side thus causing a rotation to the opposite side.

    04:46 And usually, what happens is, it doesn't really exaggerate when I check in flexion or extension.

    04:52 So, here is another example for a type I somatic dysfunction.

    04:57 As I'm palpating the segments from T3 to T6, They're more posterior now on the right side.

    05:02 and when I motion test in flexion and extension, it doesn't really have a change.

    05:06 So now you have T3 to T6, you know it's a neutral curve and you know it's posterior on the right.

    05:12 And following Fryette's principle no. 1, you assume that the side-bending is left.

    05:18 Taking a closer look at Fryette's 2nd principle, again, this is usually a single unit in a non neutral spine.

    05:25 meaning, there is a flexion or extension component, you're gonna have the bodies of the vertebrae rotate and side-bend the same direction.

    05:34 So with a type II dysfunction, usually this is due to some sort of trauma.

    05:38 The intertransverse ligament, the interspinous ligaments, the facet is stuck.

    05:42 And so, there is a problem here of one single segment as it moves on the one below.

    05:48 Again, it's maintained by the small muscles, those deep muscles in the thoracic spinem, in between the thoracic spine.

    05:56 And usually when you're treating, you should treat these before type I dysfunctions.

    05:59 Sometimes you might even find a type II dysfunction mixed in a type I at the apex or at the top or bottom of a type I curve.

    06:07 Let's take a closer look at type II dysfunctions.

    06:10 So type II dysfunctions occur in a non-neutral spine.

    06:13 meaning that there is a flexion or extension, freedom or component.

    06:16 Remember that we name somatic dysfunctions for the freedom of motion.

    06:20 And so with extension dysfunction, what we usually find typically is that there is a posterior transverse process, a segment that resist anterior springing on the right or left that gives us a rotational freedom.

    06:33 What happens in extension, is that rotational freedoms seems to even out, it becomes more symmetric because that is the freedom of motion.

    06:40 And when I try to flex, it becomes more pronounced.

    06:46 You'll see that rotation become stiffer and harder to spring in the barrier.

    06:53 So, what happens is when I extend the spine, the facets will close.

    06:59 And when I flex the spine, the facets will open.

    07:02 In extension dysfunction, what happens is one of those facets is not opening.

    07:08 And because that facet stays closed, it causes that vertebra to rotate and side bend to that side.

    07:15 The opposite occurs in a flexion dysfunction.

    07:17 So if I find asymmetry in the spine and I have someone flex forward, then the dysfunction seems to disappear or become more symmetric.

    07:26 But then when I have them extend, that asymmetry now becomes more pronounced.

    07:30 So what happens in extension is the facets close and what happens in a flexion dysfunction is one of the facets is not closing and that causes the vertebrae to pivot and cause rotation and side-bending to the opposite side.

    07:45 So, here's an example describing a type II somatic dysfunction.

    07:50 If we have one single segment, let's say T3, and you find a motion restriction of that transverse process to be more posterior, here let's say on the right side.

    07:59 So I have a posterior transverse process on the right when I try to push anteriorly, it resist springing, there might be some tenderness, some other tissue texture changes at that location.

    08:09 And now if I motion test that segment, it's gonna actually improve in flexion or improve in extension.

    08:15 So there is a non-neutral, there is a position of ease.

    08:18 So following Fryette's principle, we would assume that rotation, either rotation right here is gonna be coupled with side bending to the same side.

    08:29 So here our somatic dysfunction will be T3 flexed, the freedoms in flexion, and is side bent, rotated to the right.

    08:38 We name the motion of T3 as it moves on T4.

    08:42 So in type II non neutral somatic dysfunctions, there's always a flexion or extension component.

    08:49 The side-bending rotation are coupled to the same side.

    08:51 The restricted facet pretty much acts like a pivot which rotation occurs causing that asymmetry.

    08:58 And the segment will appear more symmetric at some point in the sagittal range of motion.

    09:05 The lesion becomes more prominent as you move in the opposite direction.

    09:10 Here are a couple of charts for you to look over and review.

    09:14 This helps to summarize the differences between a flexion or extension type II somatic dysfunction.

    09:21 This is additional chart.

    09:23 What we're looking at here is what happens in each specific somatic dysfunction, especially when the facet is restricted.

    09:30 So what I would recommend if you could get your hands on anatomical models of the thoracic spine and look at what happens when you try to flex and open the facets but don't allow one of the facets to open, you'll see that that transverse process then becomes more posterior and side bent and rotated in the same direction.

    09:52 The opposite occurs when we're looking at a flexion dysfunction.

    09:56 If I am able to open both but I'm not able to close one of the facets, you'll notice that the side-bending rotation is gonna occur to the opposite side.

    10:06 So the best way to really understand this a little better is to get model thoracic segments and really practice looking at what occurs when you have a facet that doesn't open, when you flex and doesn't close when you try to extend the segment.

    10:20 When we write out somatic dysfunctions, there is a specific way that we have to write somatic dysfunctions.

    10:29 For type II dysfunctions, we always write the rotation before the side-bending because the rotation is the more important component in a type II dysfunction.

    10:39 Whereas in a type I dysfunction, side bending is written before rotation.

    10:43 This is because the side-bending is the more important component in a type I dysfunctions due to the muscles pulling on the side, causing the side-bending.

    10:55 Some key review points, take home points.

    10:58 In type II somatic dysfunctions, they are non neutral dysfunctions, meaning there is a flexion or extension components.

    11:04 In that instance, rotation and side bending are coupled to the same side.

    11:08 When we notate it, we always write the rotation first in a type II dysfunction.

    11:14 Flexion dysfunctions in a type II dysfunction become more prominent in extension and vice versa.

    11:20 Extension dysfunctions become more prominent in flexion.

    11:24 In an extension dysfunction, the facet on the same side is restricted.

    11:28 In flexion dysfunctions, the facet on the opposite side is restricted.

    11:33 In a type I dysfunction, this occur in a neutral spine and remember that it is usually a group curve, so it has to be at least 3 segments.

    11:42 Rotation and side-bending are coupled to opposite sides.

    11:46 When we notate it, we usually put the side-bending component first and in a type I dysfunction, there's really little change in flexion or extension.

    11:56 Let's do a practice question together.

    11:58 So in your patient, you find a right posterior transverse process to the level of T7 and it improves with flexion and is worse with extension.

    12:06 What is the somatic dysfunction diagnosis and which Fryette's principle does it follow? So here, we have a single segment and it has a freedom in flexion.

    12:20 So you know that it's going to follow Fryette's principle type II because this is a non neutral dysfunction.

    12:25 So this is T7 and it's flexed.

    12:28 Because we felt that it is more posterior on the right side, that tells you that the segment is rotated right.

    12:33 So knowing that it's flexed and rotated right, we can then follow the principle and assume that the side-bending is occuring in the same direction so it's also side-bent right.

    12:43 So we here have a T7 flexed, rotated right and side bent right dysfunction.

    12:48 So in this practice item, we find that your patient has posterior transverse processes from T1 to T5 on the left side.

    12:56 And they do not change with flexion or extension.

    12:59 What is your somatic dysfunction diagnosis and which Fryette's principle does it follow? So here, we note that this is a group curve from T1 to T5 and they are all posterior on the left side which means that they're rotated left.

    13:17 Since they do not change with flexion or extension, you know that this is a neutral curve.

    13:22 So neutral curves usually follow's Fryette's principle no 1.

    13:26 So because it's T1 to T5, neutral curve and we know it's rotated left, since we follow Fryette's principle no 1, we know that rotation and side-bending are opposite.

    13:38 That brings us to the diagnosis of T1 to T5 neutral, side bent right and rotated left.

    About the Lecture

    The lecture Fryette's Principles by Sheldon C. Yao, DO is from the course Osteopathic Diagnosis of the Thoracic Spine Region. It contains the following chapters:

    • Fryette`s Principles
    • Neutral (Type I) Dysfunctions
    • Fryette`s Second Principle
    • Type II Dysfunctions
    • Non-Neutral (Type II) Segmental Dysfunctions
    • Review Points

    Included Quiz Questions

    1. 3
    2. 1
    3. 2
    4. 4
    5. 5
    1. Rotation to the right
    2. Rotation to the left
    3. Flexion to the left
    4. Flexion to the right
    5. Extension to the left
    1. Transverse process
    2. Spinous process
    3. Superior articular process
    4. Inferior articular process
    5. Lamina
    1. ERS-left
    2. ERS-right
    3. FRS-left
    4. FRS-right
    5. ERS-bilateral
    1. ERS-right
    2. ERS-left
    3. FRS-left
    4. FRS-right
    5. ERS-bilateral
    1. T3–T6 NSlRr
    2. T3–T6 NSR-left
    3. T3–T6 ESlRr
    4. T3–T6 ESR-right
    5. T3–T6 NSR-right

    Author of lecture Fryette's Principles

     Sheldon C. Yao, DO

    Sheldon C. Yao, DO

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