Lumbar Facet Joint Syndrome: Causes and Preventions in the Workplace

Background

With the rapid development of the world, manual labour demands are getting higher, this brings many threats to workers’ well-being and rise of many musculoskeletal disorders on the lower backs. Lumbar facet joint syndrome, account for up to 40% of the lower back pain [1], has been a very prevalent issue in the current society across all age span [2]. Based on the data of previous studies, as people grow older, the risk of facet joint syndrome gets higher [3]. Lumbar facet joint syndrome (LFJS) is an articulate disorder on the lumbar facet joint, which is also called zygapophysial joint (z joint), it impacts the innervation and creates pain and tenderness in the lower back region. Patients with this syndrome can experience pain in the lumbar facet joint or joint capsule and may be spread down to the limb if the syndrome is severe [3]. Some functional movements that involves the movement of trunks will also be affected as well. The anatomy of the facet joint prevents excess rotation and extension but allows greater range of flexion. In a neutral position, the articular surface runs vertically, the superior articular processes face medially from the lower vertebral body and the inferior articular processes face laterally from the upper vertebral body. These two processes are parallel and face each other, which form the facet joint, the joint is surrounded by facet capsule to further stabilize the joint. In this paper, I will focus on the causes and prevention of the LFJS.

Etiology

The degeneration of the intervertebral disc can lead to the facet joint syndrome. The intervertebral disc and two facet joints are best described as “three-joint complex” [4]. Each joint assists and impacts the other two, and the degeneration in one joint will affect the biomechanics of the entire complex. When intervertebral disc begins to degenerate, the annular fibers begin to shift more load posteriorly onto the facet joints, which leads to further degeneration. Repetitive lumbar movements, especially extension and axial rotation, would also lead to the LFJS. When lumbar is in the extension movement, the inferior articulate process move inferiorly and posteriorly until the two spinous processes impact each other and restrain the extension movement. The loading force on the facet joints is greater in an extensive position compare to the force in neutral position [1]. And the lumbar extensor muscles further increase the face loading during the active lumbar extension, which further speed up the degeneration process [5]. During axial rotation, the superior articular process and inferior articular process impact each other and prevents excessive rotation to occur. This protects the intervertebral disc from excess rotation [1]. However, because of the mechanism, the impact force on the facet joint during axial rotation can lead to the degeneration and cause the syndrome. The excess movement of the lumbar facet joint also causes the microdamage and degeneration to the facet capsule which could further cause facet joint degeneration [1]. Repetitive lumbar movements causing lumbar facet joint syndrome is also backed up by numerous amount of studies on athletes, specifically those who participate in sports that involve repetitive trunk rotation and extension, such as tennis. In a study done by Alyas and their colleagues on a group of elite adolescent tennis players, they found that facet joint syndrome is prevalent among 70% of the sample [6]. Many golf players also experience lower back pain which is surprising since many people don’t associate golf as a high-risk sports. During the swing phase, the lumbar spine is exposed to explosive axial torsion force, which is one of the risk factors for LFJS [7]. In addition, the misconception of people that golf is not a risky sport leads to people participate without practice and caution, which further increases the risks of injury [7]. Lordotic posture can also cause the LFJS. In a lordotic posture, lumbar curve of the spine is more defined and the lumbar joint is in a prolonged extended position. More pronounced lumbar curve increases the anterior shear force and creates a vertebral slippage promotion in an anterior direction, as well as disc space narrowing, which can lead to a overloading to the lumbar facet joints which leads to the facet joint arthritis [8][9][10].

Prevention among manual labours

With the rapid industrialization, comes to great risk of injuries and musculoskeletal disorders. Lower back pain (LBP) is especially one of the most common complaints among manual labours and lumbar facet syndrome is one of the leading cause of LBP. As society has brought up more awareness on this issue, many companies start to implement many intervention to lower the LBP complaints. One of the most commonly used methods is to educate workers safe methods to perform their essential duties, since this is method is accessible and bring less financial burden. For example, health and safety professionals would teach workers safe ways to do their tasks during training session (i.e.: lifting weight with squat style instead of bending your back, don’t turn by twisting your trunk and take steps instead). However. Study have found that this method has no significant evidence that it would prevent back pain among workers [11]. Workstation redesign is another popular intervention to prevent the LFJS and general LBP. The purpose of this intervention is decrease the unnecessary movement of the trunk. Professional ergonomists would use tools like NIOSH to determine if the workstation is safe and pose minimal risk to the worker. Like increase the height of the workstation to decrease bending and suit the worker better, or putting most used tools in front of you to minimize side reaching. However, each worker has different anthropometric data and companies can’t meet everyone’s need. And very often, redesigning a workstation is impossible due to the limitation of space and budget. With the development of new technologies, the Inertia Measurement Unit (IMU) sensor technology, has been incorporated into construction industry. IMU sensor is a wearable and real-time movement feedback equipment. It has two parts and one is placed on the middle of upper back and another one is placed on the back of the head. These parts can process the data in real life and detect ergonomically hazardous posture and motion on the torso and neck, then send alarm signal onto the user’s smartphone application. This real-time feedback allows the user to adjust themselves and avoid hazardous postures [12]. IMU sensor enables worker’s awareness and self-management of ergonomically hazardous operational pattern and should be implemented in other industries in the future [12].

Conclusion

In conclusion, this paper reviews the etiology of the LFJS and preventative interventions in workplace. The causes of the LFJS can be categorized into three points: 1, degeneration of the intervertebral disc that causes the degeneration of lumbar facet joints; 2, repetitive lumbar joint movement; 3, lordotic postures. In many workplaces, many workers struggle with LFJS yet there hasn’t been any effective method to manage it. Educating workers is still the most used prevention but has been proven to be ineffective. Workstation redesign is a good prevention but companies are not able to accommodate due to limited space and budget. The new real-time motion feedback technology is promising to prevent workers to perform risky postures, but it still needs time for further development and on-site tests.

Reference:

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