Musculoskeletal models have historically been exclusively static. In other words, they don’t move like they should. That is, up until Dynamic Disc Designs developed a spine model with both an annulus and nucleus to allow six degrees of freedom. With a gel-like viscoelastic nucleus pulposus and a tougher outer annulus fibrosus, educators have been touting these new musculoskeletal models as revolutionary.
This model with the bulging nucleus is exactly what we see in real discs – its brilliant. It is a perfect teaching tool to illustrate the difference between flexion motion and flexion moment/torque and the disc bulge as an injury mechanism.
Low back pain is the number one cause of disability world-wide and so, the development of musculoskeletal models is important if solutions are to be found. We are continuing to learn that it is the volumetric spacing (or disc height) that is most important when it comes to keeping a spine healthy. Disc height changes are dynamic and related to load and recovery … engaging with a patient on what that truly means is an important part of being a doctor.
Clinical work-ups of musculoskeletal spinal problems almost always arrive a disc height as the common denominator. Helping patients understand what this common finding means as it relates to disc bulge, disc herniation, disc protrusion, disc extrusion, nerve root encroachment, and discogenic pain can be very effective in building a solid relationship with your patients.
Often patients will explain to their doctors that they exhibit spine symptoms when they bend backwards for example. Dynamic Disc Models can now assist the doctor with a viscoelastic core showing how the facets approximate (or rub) when a person bends backwards for example. Otherwise, the patient has no clue as to their pain generator. On the converse, if a patient explains pain when they bend forwards, now the doctor can demonstrate how the discs are forward and under compression when there is a bending forward movement.
Previous immovable models could not allow patient engagement. But with a movable spinal motion segment with antomical details highlighting discogenic innervation, a patient can clearly see why and where it hurts. This sets the foundation of why the patient requires to do what the doctor suggests.
If patients cannot see why they should do (or not do) certain activities, clinical results will suffer. Motivation is driven by knowledge. And in the new era of 4D, a dynamic model should be an important part of driving home important take-home messages about spine.