Introduction:

Degenerative disc disease (DDD) of the lumbar spine is a common cause of significant morbidity in individuals of productive age group. Despite advancements in surgical techniques, there remain critical knowledge gaps with regards to understanding the causes of occurrence and progression of disease in individuals, the variability of symptoms in patients with an identical radiological picture, the indications of surgery and its bearing on eventual outcomes of non-surgical or surgical management. Correlation of the histological changes in the intervertebral disc with the clinical and radiological findings can provide valuable insights into the etiopathogenesis of lumbar DDD. In this study, we examined the histology of surgically procured disc specimens in patients with lumbar DDD and correlated it with clinical and radiological findings.

Methods

Specimens of the diseased disc were procured during the course of surgery for lumbar degenerative disorders in prospectively recruited adult patients at a single centre. All patients underwent single-level lumbar decompression with or without instrumented fusion. After adequate tissue processing, the disc specimens underwent histopathological evaluation according to a previously validated quantitative Histopathological Degeneration Score (HDS; a scoring system of cumulative 15 points over 4 criteria - cell density, structural alteration, granular changes and mucous degeneration). Clinical (visual analog scale and revised Oswestry Disability Index; VAS and r-ODI) and radiological (mean disc space height on plain radiographs; Modic changes and modified Pfirmann grade on MRI) evaluation was performed both preoperatively and postoperatively (at 6 months follow-up). An association was sought between the cumulative HDS scoring and the clinicoradiological parameters.

Results

A total of 102 patients (42 males and 60 females, median age of 40.2 years) with a clinicoradiological diagnosis of lumbar DDD were included in our study. The median HDS scores for male and female patients were 9.357 and 10.13, respectively. Univariate analysis revealed that none of the preoperative radiological findings (disc space height, Pfirmann grade, Modic changes) correlated with the cumulative HDS. However, both preoperative VAS and r-ODI scores showed a statistically significant correlation with HDS (p = 0.03 and 0.045, respectively). Postoperative VAS score and r-ODI scores did not show a significant correlation with the HDS.

Discussion

The results of this study point towards a possible correlation of histological changes in the intervertebral discs in patients with DDD, with their clinical symptoms. If validated by multi-centric and multi-ethnic studies with a larger sample size, these can be the focus of novel diagnostic and therapeutic strategies to treat lumbar degenerative disc disease.