Fryette’s laws, also known as Fryette’s principles or Fryette’s osteopathic laws, describe the biomechanics behaviour of the vertebral column, during different types of spinal motion. These laws were developed by American osteopathic physician Harrison Fryette in the early 20th century and are commonly taught in Osteopathic schools. Fryette’s laws are used to understand the complex interactions between vertebral segments and help diagnose and treat spinal dysfunctions. Though there is debate on the validity of Fryette’s theory of spinal mechanics as spinal mechanics are quite complex.
Fryette’s laws consist of three principles:
- Fryette’s First Law
- When the spine is in a neutral or slightly flexed position, side-bending and rotation occur in opposite directions.
- In other words, if you rotate the spine to one side, the spine will naturally want to side-bend in the opposite direction.
- This law applies primarily to the thoracic and lumbar regions of the spine. For example, if you rotate the thoracic spine to the left (counterclockwise when viewed from above), it will tend to side-bend to the right.
- Fryette’s Second Law
- When the spine is in a hyper flexed or hyper extended position, side-bending and rotation occur in the same direction.
- In contrast to the first law, when you rotate the spine to one side, it will also side-bend in the same direction.
- This law mainly applies to the lumbar region of the spine. For example, if you rotate the lumbar spine to the left, it will also side-bend to the left.
- Also is more specific to one or two vertebrae versus a global curve
- Fryette’s Third Law
- When motion is introduced in one plane (e.g., flexion/extension), motion in the other two planes (e.g., side-bending and rotation) is reduced.
- This law suggests that the spine has a limited degree of motion in multiple planes simultaneously.
These laws help osteopathic practitioners understand and diagnose spinal dysfunctions and facilitate treatment. By assessing the direction and quality of motion in the spine, they can develop treatment plans to address issues such as vertebral dysfunction and restore normal spinal function. Additionally, Fryette’s laws are considered important for understanding the relationship between spinal mechanics and overall health and well-being.
If you feel that you have been assessed and find you are not making any progress in spinal mobility or pain, it may be a good idea to seek out an Osteopathic manual therapist to help you through that process.
Crux Osteopathy 