Is it true that intervertebral discs can return to their original position after being displaced?

Yes, it’s true that displaced intervertebral discs (herniated discs) can resolve spontaneously. Disc herniations are displacements of the contents of the intervertebral disc beyond its normal space, which can lead to pain such as sciatica. These disc herniations can be classified according to their degree of displacement (Fardon et al, 2014):

1. A bulging disc is a slight extension (less than 3 mm) and is generally considered a normal variation.
2. A disc protrusion protrudes more widely (more than 3 mm), but remains partly contained within the disc space.
3. A disc extrusion is present when at least one plane of herniated disc tissue protrudes beyond the dimensions of the disc space.
4. A sequestrated disc is even more complex, as part of the disc becomes detached and displaced.

The phenomenon of spontaneous disc herniation resorption is well documented in the literature, but the natural course of disc herniation remains unclear. In the absence of progressive neurological deficits, the general consensus is to recommend non-surgical treatments for this condition (Liu et al, 2023). Without specific intervention, two-thirds of patients can expect regression of the herniated disc, while 85% will have resolution of symptoms within a year (Zhong et al, 2017).

A recent literature review identified 16 scientific publications describing 360 cases of lumbar disc herniation. The probabilities of spontaneous regression for bulging, protruded, extruded and sequestrated discs were 13%, 53%, 70% and 93% respectively. Extruded and sequestrated discs were more likely to regress completely than smaller morphologies. The authors also found that symptom improvement was associated with disc regression. The mechanisms underlying these spontaneous regressions are as yet unknown, although several theories have been formulated (Rashed et al, 2023).