Clin Orthop Surg.  2018 Jun;10(2):210-215. 10.4055/cios.2018.10.2.210.

Revalidating Pfirrmann's Magnetic Resonance Image-Based Grading of Lumbar Nerve Root Compromise by Calculating Reliability among Orthopaedic Residents

• Kaliya-Perumal AK
• Ariputhiran-Tamilselvam SK
• Luo CA
• Thiagarajan S
• Selvam U
• Sumathi-Edirolimanian RP

• KMID: 2411747
• DOI: http://doi.org/10.4055/cios.2018.10.2.210

Abstract

BACKGROUND
Intervertebral disc herniations lead to subsequent compromise of the nerve root. The root can either have a mere contact with the disc material or be pushed aside or compressed. This was earlier graded by Pfirrmann and colleagues. We intend to revalidate this grading system by performing a reliability analysis among orthopaedic residents.
METHODS
Fifty axial cut magnetic resonance (MR) images of the affected lumbar disc level that belonged to different patients (age, 37.8 ± 10.4 years; 33 males and 17 females) were chosen and given to five orthopaedic residents for grading according to the Pfirrmann's MR image-based grading of lumbar nerve root compromise. Responses were received in the form of categorical variables and reliability was assessed.
RESULTS
On doing percentage statistics, we found that 14 images had 100% agreement, 22 had 80% agreement and 14 had 60% agreement. We inferred an overall agreement of 80% ± 15.1%. In addition, interrater reliability was determined by calculating the Fleiss' kappa, which was found to be 0.521, signifying moderate agreement. Intrarater reliability was determined by calculating Cohen's kappa, which was found to be 0.696, signifying substantial agreement.
CONCLUSIONS
Our residents took only a short time to learn and reproduce this grading system as ratings that proved to be moderately reliable. Even though the value of kappa was slightly lower, reliability was similar to that of the original authors. We think that this grading system can be adopted in day-to-day practice by framing appropriate rules to interpret MR images where the nerve roots are not visible.

Keyword

Intervertebral disc; Nerve root compression; Spinal stenosis; Radiculopathy; Reliability

MeSH Terms

Humans
Intervertebral Disc
Male
Radiculopathy
Spinal Stenosis

Figure

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  Fig. 1 Axial cut magnetic resonance images at the affected lumbar disc levels of different patients (arrows indicate the side which was graded). (A) Grade 0 (normal), when there is no contact of disc material with the nerve root. (B) Grade 1 (contact), when there is contact of disc material with the nerve root. (C) Grade 2 (deviation), when there is deviation of the nerve root dorsally. (D) Grade 3 (compression), when the nerve root is compressed between the spinal canal wall and the herniated disc.

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