Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

Progression of lumbar disc degeneration: a 14-year follow-up study with a detailed examination of variables in Pfirrmann classification (#149)

Niko Murto 1 , Teija Lund 2 , Katariina Luoma 3 , Hannu Kautiainen 4 5 , Liisa Kerttula 6
  1. Department of Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
  2. Department of Orthopaedics and Traumatology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
  3. Department of Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
  4. Primary Health Care Unit, Kuopio University Hospital, Kuopio , Finland
  5. Folkhälsan Research Center, Helsinki, Finland
  6. Department of Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland

INTRODUCTION

The Pfirrmann classification is widely accepted for grading lumbar disc degeneration (DD). Although it has only been validated with cross-sectional data, it has also been utilized in longitudinal studies.
This study aims to conduct a detailed examination of the different disc structures included in the Pfirrmann classification to evaluate its utility in longitudinal studies.

 

METHODS

A fellow in musculoskeletal radiology (the first author) assessed lumbar DD in 19 males over a 14-year follow-up period from mean age 37 (SD 0.7) to 51 (0.7) utilizing the Pfirrmann classification. Additionally, the signal intensity of the nucleus pulposus (NP SI) was assessed quantitatively [1]. Nucleus pulposus heterogeneity (NP inhom), annulus fibrosus border distinction (AF border), and disc height (DH) were evaluated through visual grading (Table 1).
For all study subjects, a summary score of the variables of interest was calculated by adding up the individual scores of each lumbar disc. The change in the Pfirrmann summary score of the lumbar spine was compared against changes in the summary scores of NP SI, NP inhom, AF border, and DH.

 

RESULTS

During the follow-up period, a significant increase in the Pfirrmann summary score by 3.3 points (95% CI: 2.4 to 4.1) from a mean score of 13.5 (SD 1.8) at baseline was detected (p < 0.001).
The mean NP SI of the whole lumbar spine significantly decreased by -0.43 points (95% CI: -0.73 to -0.03) from a mean score of 2.08 (SD 0.24) at baseline (p < 0.001).
Changes in the scores of NP inhom, AF border and DH varied across the whole lumbar spine among disc levels (Table 2) and individual subjects (Table 3).
A strong correlation was found between changes in both AF border and NP inhom summary scores with the Pfirrmann summary score, whereas changes in NP SI and DH showed moderate and weak correlations, respectively (Table 4).

 

DISCUSSION

The increase in the Pfirrmann summary score and the decrease in NP SI align with the expected progression of lumbar disc degeneration. The occurrence of changes in NP inhom, AF border and DH showing variations among subjects suggests individual differences in the progression of disc degeneration. Notably, changes in NP inhom, AF border, and DH were also prevalent at the L1/L2 and L2/L3 levels though disc degeneration is typically regarded as less common in the upper lumbar spine.
 The strong correlation between changes in both AF border and NP inhom with the Pfirrmann summary score suggests that these factors are potentially sensitive markers of degeneration. Meanwhile, the moderate and weak correlations with NP SI and DH changes indicate a multifaceted pathway in disc degeneration. This study supports the applicability of the Pfirrmann classification in longitudinal assessments and highlights the complexity of lumbar disc degeneration.

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  1. 1. Murto N, Luoma K, Lund T, Kerttula L (2023) Reliability of T2-weighted signal intensity-based quantitative measurements and visual grading of lumbar disc degeneration on MRI. Acta radiol 2023;64(6):2145-2151. https://doi.org/10.1177/02841851231169079