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The Multifidus: why is it critical, and why does it falter?

Musculoskeletal disorders are the biggest cause of disability. Despite the billions spent, the problem is just getting worse. Latest medical guidelines strongly recommend exercise therapy as the first-line-treatment for musculoskeletal disorders instead of much more expensive surgeries.

By Professor Emeritus John Carlson,  Co-Founder of getback

getback rehabilitation treatment focuses on the role played by the deep stabilising muscles of the spine, particularly the multifidus. But why is the multifidus so prone to atrophy and injury?

Why is the multifidus so critical to back stability?

Control of the lumbar spine and vertebral stability during movement, and while maintaining upright posture, are important components in avoiding low back pain and disability.

The multifidus muscles, running the length of the spine from the pelvis to the last vertebra of the neck, play a crucial role in back stability. These small but powerful deep muscles are attached directly to the vertebral bones, under the larger muscles which produce major spinal movements.

Compared to other lumbar muscles, the multifidus has short muscle fibre length but a high cross-sectional area (CSA). This anatomy allows the multifidus to produce stabilising forces over a small operating range (typically spanning two vertebral segments), thus acting as stabilisers rather than prime movers.

Empirical research has identified reduced strength and endurance capacity in the lumbar/thoracic and cervical extensors and flexor muscles in patients with chronic back and neck pain. When strength and endurance are reducing in these muscles, the multifidus is required to be constantly ‘switched on’ to maintain and control vertebral stability.

However, if the multifidus becomes overloaded and fatigue accumulates, a lack of blood flow and increased or changed metabolic demand can result in spasm and the muscle ‘switching off’ – a unique quality of this important muscle.

When the multifidus loses function and goes ‘offline’, the larger superficial muscles are called upon as controllers, a role for which they were not designed. The superficial muscles attempt to act as controllers mainly through compression, which creates flow-on problems to other areas including facet joints and ligaments.

The critical role of the multifidus in providing muscular stability for the spine and avoiding flow-on impacts cannot not be overestimated.

multifidus

What factors are causing the multifidus muscles to falter more often?

Asymptomatic patients whose multifidus have been examined demonstrate very few abnormalities in this musculature, while the vast majority of research studies correlate atrophy (weakness and reduction in size) of the multifidus with pain, poorer outcomes and functional problems.

A number of prior investigations have described this multifidus atrophy and replacement by fat after low back injury, a pathologic process that is closely correlated with Low Back Pain (LBP).

As the multifidus is constantly required to maintain stability and postural control, it is placed under demand while we move, stand and sit during daily activities. Our increasingly sedentary lifestyles put even more strain on our lower backs and necks as gravity acts to pull the spine forward – for example, when we spend many hours looking at screens.

Unless we are actively exercising our spinal musculature to be stronger, everyday issues such as dehydration, vibration during driving, poor sitting posture and extreme inactivity in daily exercise predispose us to injure the spinal musculature.

Why is it difficult to rehabilitate the multifidus?

Optimal functioning of the spinal muscle system is important for control and protection of the spinal segments following injury. Even when painful symptoms are initially resolved, it has been shown that the deep musculature does not return to full function, increasing the likelihood of recurrent symptoms. In particular, if multifidus strength is still deficient, the predisposing muscular conditions are vulnerable to another episode of back or neck pain.

Man and woman testing the getback devices

There is broad consensus in the need for active reconditioning exercise in the treatment of chronic spinal pain. While there is little agreement on which exercise regimens are most effective, the type of muscle work seems to be important: strength development in the deep spinal musculature.

The most difficult aspect, however, is how to specifically strengthen deep muscles which are very difficult to isolate. Normal freestanding strength training can be problematic, as the gluteal muscles (hip flexors) ‘take over’ the movement as the prime mover, bypassing multifidus involvement.

Similarly, other floor exercises and gym machines are not able to isolate, target and safely and progressively strengthen the multifidus by staged, measurable overload.

At getback we use TGA registered Medical Devices which through research design and testing have created a rehabilitation system which is specific, targeted, measurable, valid and reliable.

Another difficult aspect in recovery rehabilitation is to address strength development in every movement plane of the spine. In many instances, injury arises when compound movements are employed such as bending forward and rotating (for example, while digging and gardening).

In these everyday movements, ongoing functional strength is essential. The getback devices are designed to provide specific, targeted and isolated rehabilitation in all movement planes, including flexion and extension, lateral flexion and rotation.