degenerative spondylolisthesis model

Goal of the Study?

In this paper 1, the authors review the general principles of degenerative spondylolisthesis, including the diagnosis, characteristics, management and treatment.

 

What is degenerative spondylolisthesis?

Degenerative spondylolisthesis results from the progression of degenerative changes in the intervertebral disc (IVD) and facet joints that lead to destabilizing one or more vertebral segments. The term degenerative spondylolisthesis was first used in 1964 by Newman and was initially related to slipping of the anterior vertebral body in the lumbar region of the elderly female population. Spondylolisthesis was further classified in 1963 by Wiltse, Newman and Macnab into six categories, with degenerative spondylolisthesis defined as Class III.

 

 

Who does it impact and what are the symptoms?

Degenerative spondylolisthesis predominantly impacts elderly female patients with a ratio of 5:1 compared to men and is generally found in those over 50 years of age. Black women are three times more likely than Caucasian women to develop the condition. While there has been no correlation between body mass index (BMI) and degenerative spondylolisthesis in men, there is a significant relationship between BMI and the development of L4 listhesis in women. 

In degenerative spondylolisthesis, vertebral slipping usually occurs in the L4-L5 and rarely exceeds 30% of the vertebral body’s anteroposterior diameter. This condition may be asymptomatic, and there is no clear relationship between symptoms and the degree of slipping. However, the degree of degeneration does increase the risk of progression to lumbar spinal stenosis and the possible presentation of clinical symptoms. When there are symptoms, the most common is low back pain, with or without radicular pain. Neurogenic claudication occurs in 75% of patients. As slipping progresses, facet hypertrophy, thickening of the yellow ligament, and disc bulging can increase compression and sometimes trigger cauda equina syndrome symptoms. This can then disrupt motor and sensory function to the lower extremities and bladder.  

 

Diagnosis and Treatment?

Most often, radiography is the first approach to diagnosis, with a standing lateral radiograph to evaluate instability in the flexion and extension. If neurological symptoms are present, an MRI is used as this tool can assist in evaluating the spinal cord and nerve roots and the assessment of disc degeneration. 

First-line treatment generally includes pain management with anti-inflammatories and analgesics and, or physiotherapy. Surgical intervention is only required on approximately 10-15% of patients. 

 

Disc Herniation Spondylolisthesis

Spondylolisthesis is the slippage of one vertebra on another—frequently found with disc herniation. However, in this recent paper titled: “Over-reporting of the disc herniation in lumbar spine MRI scans performed for patients with spondylolisthesis” 1 they sought to find if disc herniation is over-reported and in turn, possibly over-treated.

Spondylolisthesis is best diagnosed when the spine is under load. Many MRI scans, because done in the lie-down position, miss these small (or large) slippages. To accurately assess one for a spondylolisthesis, the spine is best visualized by x-ray in the forward bending and backward bending position. Upright MRI is also another great way to assess; however, the access to these expensive machines may not be available.

The authors of the above paper discuss how it is imperative to find an accurate diagnosis for both the conservative and surgical management of back pain.

Disc herniation is often found with spondylolisthesis. However, what they found was disc herniation reporting was often over-reported and believed that the disc herniation was more of a pseudo disc herniation rather than an actual disc herniation.

 

What do the authors mean by pseudo-herniation?

 

The authors point to a nomenclature issue. In Fardon’s 2014 paper 2 he helps clarify the language professionals use when discussing disc herniation, extrusion, protrusion and bulge. However, the authors of this paper explain that Fardon’s article does not address this nomenclature in light of spondylolisthesis.

 

They point out in this retrospective study of 258 patients that disc herniation was over-reported because the disc herniation was read with the superior vertebra in mind rather than referencing the lower vertebra. In other words, if the radiological reporting used the lower vertebra as a reference point, the reporting of a disc herniation would be much less because the outer disc border remained anterior to the posterior vertebral ring apophysis. Therefore, it is essential to deferentially diagnose whether symptoms are related to a real disc herniation or due to the mechanics of a spondylolisthesis. A spondylolisthesis can throw off the reporting in this case.

 

 

Dynamic Disc Designs creates 3d models to help reveal the dynamics of disc herniation, including the up-roofing of the disc material. This mechanism is shown in our Professional LxH Model, with the added features of spondylolisthesis.