Correlation of Straight Leg Raise Test with Magnetic Resonance Imaging Findings in Patients with Lumbar Disc Herniation

By Mian Amjad Rehman, Imran Khan, Mohammad Ali Noman, Sajid Razaq, Rafi Ullah, Khalid Masood

Affiliations

1. Department of Neurosurgery, Hayatabad Medical Complex, Peshawar, Pakistan

doi: 10.29271/jcpsppg.2025.01.137

ABSTRACT
Objective: To determine the correlation between the angle of the straight leg raise (SLR) test and the severity of lumbar disc herniation (LDH) measured by magnetic resonance imaging (MRI) in patients with LDH.
Study Design: A cross-sectional study.
Place and Duration of the Study: Department of Neurosurgery, Hayatabad Medical Complex, Peshawar, Pakistan, from February to July 2025.
Methodology: One hundred forty participants aged between 18 and 80 years with MRI-confirmed LDH and persistent low back pain or sciatica (≥6 weeks) were included in this study. The SLR test was performed for all patients, with the maximum angle for pain measured using a digital goniometre. Herniation size was assessed via MRI using the RadiAnt DICOM Viewer software. Pearson’s correlation coefficient (r) was applied to determine the correlation between the SLR angle and LDH size.
Results: The mean SLR angle was 39.64 ± 12.39 degrees, and the mean herniation size was 4.67 ± 2.30 mm. Protrusions were most common (58.6%), followed by extrusions (35.0%) and sequestrations (6.4%). A strong negative correlation (r = -0.92; p <0.001) was observed between SLR angle and herniation size.
Conclusion: The SLR test demonstrated a strong negative correlation with MRI-quantified LDH severity.

Key Words: Straight leg raise test, Lumbar disc herniation, Magnetic resonance imaging.

INTRODUCTION

Lower back pain (LBP) is a serious health issue worldwide, with around 80% of individuals experiencing at least one episode throughout their lifetime. Degenerative disc disease, as well as lumbar disc herniation (LDH), are the most prevalent differential diagnoses for LBP. About 95% of LDH occur at L4-L5 or L5-S1 levels.¹ The lumbar spine consists of five vertebrae, as well as intervertebral discs, which lead to a lordotic curve. The intervertebral discs, along with the laminae and articular processes of adjacent vertebrae, form a space from which spinal nerves exit.^2,3 The intervertebral discs make up an inner nucleus pulposus, an outer annulus fibrosus, as well as cartilaginous endplates which connect the disc to the vertebrae. LDH occurs in approximately 5 to 20 instances per 1,000 adults each year.⁴
 

The pressure from the disc herniation on the longitudinal ligament, in addition to irritation from local inflammation, results in localised back pain. Lumbar radicular pain occurs when disc material applies pressure to thaecal sac or lumbar nerve roots, which results in nerve root ischaemia as well as inflammation. The annulus fibrosus displays reduced thick- ness on the posterolateral aspect and is not supported by posterior longitudinal ligaments, rendering it prone to herniation. A posterolateral herniation was more likely to cause nerve root compression  due  to  its  closeness  to  the  nerve root.^5,6

Diagnostic procedures such as MRI are instrumental in confirm- ing disc herniation as the anatomical cause of sciatica. The signs firmly associated with MRI involve paresis, absence of knee, and positive straight leg raise (SLR) assessment.^7,8 The SLR test acts as a primary diagnostic tool for LDH, demonstrating a strong correlation with surgical outcomes due to its high accuracy for disc herniation resulting in root compression, which could necessitate surgery. The traditional SLR test conducted in the supine position demonstrates greater sensitivity compared to the seated SLR test for individuals exhibiting clinical indications of lumbar radiculopathy.^9,10 The pathophysiology of the SLR test is due to the tensile stress and traction placed on the lumbosacral nerve roots and sciatic nerve, leading to symptoms of radiculopathy.¹¹ The SLR test may yield negative results despite the presence of a disc lesion in certain cases, such as high disc herniation, central disc herniation, or chronic disc herniation.¹²

This study aimed to investigate the correlation between the SLR test and MRI findings in patients with LDH, providing valuable insights for healthcare providers and policymakers in Pakistan.

METHODOLOGY

This cross-sectional study was carried out after obtaining approval from the Ethical Review Board of Hayatabad Medical Complex, Peshawar, Pakistan (Approval No: 2314; dated: 24 November 2024). A total of 140 patients were included using a consecutive non-probability sampling technique. The sample size was calculated with the help of G*Power software based on the assumption of r = 0.3, 80% power, and 95% confidence interval.¹³

Patients aged between 18 and 80 years with suspicion of LDH, presenting with LBP with or without radicular leg pain, persisting for at least six weeks, and irrespective of the SLR test results, were included in the study. Patients with spinal trauma, previous spinal surgery, congenital deformities such as scoliosis or spondy- lolisthesis, spinal infections or tumours, cauda equina syndrome (CES), severe neurological deficits, pregnancy, breastfeeding, and those having contraindications for MRI were excluded.

After taking informed consent, the demographic and clinical variables, including age, gender, weight, height, body mass index (BMI), symptom duration, and herniation type (protrusion, extrusion, or sequestration), were documented using a structured proforma. Potential biases such as responder bias were mitigated through rigorous adherence to the study protocol and exclusion criteria.

All patients included in the study underwent a standardised SLR. The maximum angle of leg elevation was measured precisely using a digital goniometre at the point of pain onset. Lumbar spine MRI scans were obtained and analysed using the RadiAnt DICOM Viewer software. Disc herniation size in millimetres was categorised as mild, moderate, and severe.

Data were analysed using SPSS version 22. Quantitative variables (SLR angle, age, height, BMI, duration of symptoms, and herniation size) were presented as mean ± standard deviation, while qualitative variables (gender and type of disc herniation) were presented as frequencies and percentages. The sample was stratified according to gender, age, BMI, duration of symptoms, weight, height, and type of LDH. Pearson’s correlation coefficient was calculated to evaluate the relationship between SLR angle and MRI herniation size. A p-value of ≤0.05 was considered statistically significant.

RESULTS

The study included 140 patients with a mean age of 57.45 ± 17.15 years. Among the included patients, 15% were aged between 18 and 35 years, 16.4% were aged between 36 and 50 years, and 68.6% were aged above 50 years (Figure 1). There were 78 (55.7%) males and 62 (44.3%) females. Anthropometric measurements revealed a mean BMI of 18–24.9 kg/m² (35.7%) and >24.9 kg/m² (64.3%), with an average weight at 65–75 kg in 65.7% of cases and >75 kg in 34.3% of cases. The average height recorded was 1.65–1.70 m in 82.1% of cases and >1.70 m in 17.9% of cases. The duration of symptoms prior to evaluation averaged 7–10 weeks in 52.9% of cases and >10 weeks in 47.1% of cases (Table I).

Table   I:   Demographic   and   clinical   characteristics   of   patients.

Variables	Categories	n (%)	Mean ± SD
Age (years)	18-35	21 (15.0)	48.81 ± 8.70
	36-50	23 (16.4)	38.26 ± 13.38
	>50	96 (68.6)	37.96 ± 12.05
Gender	Male	78 (55.7)
	Female	62 (44.3)
BMI (kg/m2)	18-24.9	50 (35.7)	41.38 ± 12.19
	>24.9	90 (64.3)	38.67 ± 12.46
Weight (kg)	65-75	92 (65.7)	39.72 ± 11.94
	>75	48 (34.3)	39.48 ± 13.32
Height (m)	1.65-1.70	115 (82.1)	39.95 ± 12.33
	>1.70	25 (17.9)	38.20 ± 12.81
Duration of symptoms (weeks)	7-10	74 (52.9)
	>10	66 (47.1)

Table   II:   Distribution   of   lumbar   disc   herniation   types  on   MRI.

Herniation types	n (%)	Mean SLR (°) ± SD	Mean size (mm) ± SD
Protrusion	82 (58.6)	40.50 ± 12.39	4.60 ± 2.33
Extrusion	49 (35.0)	38.90 ± 12.27	4.69 ± 2.24
Sequestration	9 (6.4)	35.78 ± 13.41	5.22 ± 2.54
Sequestration was associated with the lowest mean SLR angle and the largest disc size.

Table III: Correlation between SLR angle and disc herniation size on MRI.

Variables	Categories	r	p-values
Overall (n = 140)	-	-0.92	<0.001
Age (years)	18-35	-0.86	<0.001
	36-50	-0.94	<0.001
	>50	-0.91	<0.001
Gender	Male	-0.91	<0.001
	Female	-0.93	<0.001
BMI (kg/m2)	18-24.9	-0.92	<0.001
	>24.9	-0.92	<0.001
Weight (kg)	65-75	-0.91	<0.001
	>75	-0.94	<0.001
Height (m)	1.65-1.70	-0.92	<0.001
	>1.70	-0.92	<0.001
Duration of symptoms (weeks)	7-10	-0.92	<0.001
	>10	-0.92	<0.001
Type of herniation	Protrusion	-0.92	<0.001
	Extrusion	-0.92	<0.001
	Sequestration	-0.93	<0.001
p-values were calculated using Pearson’s correlation coefficient.

Figure   1:   Age   distribution.

Among patients with lumbar disc pathology, protrusion was the most prevalent type of herniation, occurring in 82 (58.6%) patients, followed by extrusion in 49 (35.0%) patients, and sequestration in 9 (6.4%) patients. The average SLR angle was 39.64 ± 12.39 degrees, and the mean disc herniation size was 4.67 ± 2.30 mm. Notably, patients with sequestration exhibited the lowest SLR angle and the largest average herniation size (Table II).

There was a statistically significant negative correlation (r = −0.92, p <0.001) between the SLR angle and the size of the herniation (Table III). Subgroup analysis showed a consistent inverse relationship across various demographics and clinical factors, including age, gender, BMI, weight, height, symptom duration, and type of herniation. The correlation coefficients in these subgroups ranged from −0.86 to −0.94, all of which were statistically significant (p <0.001).

DISCUSSION

Research has underscored the diagnostic value of the SLR test for evaluating LDH. A study by Omar et al. showed that the SLR test had 82.8% sensitivity and 87.4% specificity compared to MRI findings. This supports the test's usefulness in clinical settings with limited access to advanced imaging. In their study of 225 patients, the SLR test correctly identified disc herniation in 84.9% of cases. This indicates that the SLR test remains a dependable screening tool, even with limitations in distinguishing multilevel pathology.¹⁴

Rehman et al. noted that while clinical examination aligns well with single-level herniation, its accuracy decreases in cases involving multiple levels. Their results showed SLR positivity in 94% of patients with confirmed LDH, further supporting the test's role in initial evaluation.¹⁵ Bashir et al. found a lower sensitivity of 48.8% for the seated version of the SLR test. This suggests that the position used for the test might affect its diagnostic performance. These variations highlight the importance of using standardised methods for administering the SLR test to ensure results are interpreted consistently in different clinical settings.¹⁶

In this study, the population's demographic characteristics are consistent with previous research, showing a mean age of 57.4 years and a male predominance of 55.7%. These findings are comparable to those of Omer et al. and align with the typical age range for patients with symptomatic LDH.^14,17 The gender distribution reflects findings from Omar et al., where males constituted 63% of participants and females constituted 37%.¹⁴ The mean BMI of 25.68 ± 1.73 kg/m² suggests that the cohort was predominantly overweight, a known risk factor for disc degeneration.¹⁸ Additionally, symptom duration averaged 10 weeks, indicating that most patients presented in the sub-acute phase, a critical window for conservative management before considering surgical intervention. These similarities reinforce the external validity of the present study’s  findings.

The primary outcome showed a strong negative correlation (r = -0.92, p <0.001) between the SLR angle and the herniation size. This suggests that patients with more limited leg elevation had larger disc protrusions. This finding is consistent with Omar et al. who found that lower SLR angles were linked to increased nerve root compression.¹⁴ Notably, when analysed by herniation type, sequestration was linked to the lowest mean SLR angle and the largest disc size. This gradient of functional severity supports the idea that the SLR test could serve not only as a diagnostic tool but also as an indicator of disease severity. The distribution of herniation types in this study of protrusions (58.6%), extrusions (35.0%), and sequestrations (6.4%) was comparable to that reported by Azemi et al.¹⁹ The inverse relationship between SLR restriction and herniation size suggests that the test could be useful not only for diagnosis but also as a functional indicator of severity. However, clinical tests such as SLR should be interpreted in conjunction with imaging, especially in atypical or multilevel cases.²⁰ These results align with Rehman et al., confirming the reliability of SLR in single-level herniations but highlighting reduced accuracy in multilevel disease.¹⁵ Similarly, the variability observed by Bashir et al. highlights the importance of standardisation in the test performance. These findings collectively confirm that the SLR test is a simple, cost-effective, and highly sensitive clinical tool, especially valuable in resource-limited settings. However, it is crucial to interpret SLR results in conjunction with imaging, particularly for atypical cases or when considering surgical   planning.

This study's cross-sectional and single-centre design may limit the generalisability of its findings. Despite efforts to standardise SLR testing, some inter-observer variability might still exist. Additionally, MRI measurements were taken using a single software platform, which could yield slightly different results compared to other systems. To further validate these findings and investigate the prognostic value of SLR in treatment outcomes, future multicentre and longitudinal studies are recommended.

CONCLUSION

This study revealed a strong negative correlation between the SLR angle and LDH severity on MRI. This association indicates that SLR can aid in diagnosing LDH and assessing its functional impact. While MRI remains the gold standard, incorporating SLR findings can improve clinical decision-making, especially in resource-limited settings. However, due to the single-centre, cross-sectional design, caution is needed when interpreting the results. Future multicentre studies with larger cohorts are recommended to validate SLR's prognostic role in guiding treatment.

ETHICAL  APPROVAL:
Ethical approval was obtained from the Ethical Review Board of Hayatabad Medical Complex, Peshawar, Pakistan (Approval No: 2314; dated: 24 November 2024).

PATIENTS’  CONSENT:
Informed consent was taken from all participants included in this  study.

COMPETING  INTEREST:
The  authors  declared  no  conflict  of  interest.

AUTHORS’  CONTRIBUTION:
MAR: Conceived and designed the study, supervised the project, and drafted the manuscript.
IK: Assisted in radiological data interpretation and literature review.
MAN: Final  approval.
SR: Contributed to the patient recruitment and data collection.
RU: Performed statistical analysis and contributed to the results interpretation.
KM: Contributed to the radiological data collection.
All authors approved the final version of the manuscript to be published.

REFERENCES

1. Amin RM, Andrade NS, Neuman BJ. Lumbar disc herniation. Curr Rev Musculoskelet Med 2017; 10(4):507-16. doi: 10. 1007/s12178-017-9441-4.
2. Waxenbaum JA, Reddy V, Williams C, Futterman B. Anatomy, Back, Lumbar Vertebrae. [Updated 2023 Jul 30]. In: Stat-Pearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: httpss://www.ncbi.nlm.nih.gov/ books/NBK459278/.
3. Bonczar M, Koszewski J, Czarnota W, Dziedzic M, Ostrowski P, Mozdzen K, et al. The morphology of the lumbar vertebrae: A systematic review with meta-analysis of 1481 individuals with implications for spine surgery. Surg Radiol Anat 2024; 47(1):22. doi: 10.1007/s00276-024-03509-4.
4. Kim KC, Cho HC, Jang TJ, Choi JM, Seo JK. Automatic detection and segmentation of lumbar vertebrae from x-ray images for compression fracture evaluation. Comput Methods Programs Biomed 2021; 200:105833. doi: 10.1016/j.cmpb.2020.105833.
5. Fjeld OR, Grovle L, Helgeland J, Smastuen MC, Solberg T, Zwart JA, et al. Complications, reoperations, readmissions, and length of hospital stay in 34 639 surgical cases of lumbar disc herniation. Bone Joint J 2019; 101-B(4):470-7. doi: 10.1302/0301-620X.101B4.BJJ-2018-1184.R1.
6. Schoenfeld AJ, Weiner BK. Treatment of lumbar disc herniation: Evidence-based practice. Int J Gen Med 2010; 3:209-14. doi: 10.2147/ijgm.s12270.
7. Vroomen PC, de Krom MC, Wilmink JT, Kester AD, Knottnerus JA. Diagnostic value of history and physical examination in patients suspected of lumbosacral nerve root compression. J Neurol Neurosurg Psychiatry 2002; 72(5):630-4. doi: 10.1136/jnnp.72.5.630.
8. Scaia V, Baxter D, Cook C. The pain provocation-based straight leg raise test for diagnosis of lumbar disc herniation, lumbar radiculopathy, and/or sciatica: A systematic review of clinical utility. J Back Musculoskelet Rehabil 2012; 25(4): 215-23. doi: 10.3233/BMR-2012-0339.
9. Kamal F, Quddus M, Hossain A, Rahman M, Sarkar R, Nabi S, et al. Role of magnatic resonance imaging (MRI) in the pre-operative diagnosis of lumbar disc herniation. J Dhaka Med Coll 2009; 18(1):8-14. doi: 10.3329/jdmc.v18i1.6298.
10. Rabin A, Gerszten PC, Karausky P, Bunker CH, Potter DM, Welch WC. The sensitivity of the seated straight-leg raise test compared with the supine straight-leg raise test in patients presenting with magnetic resonance imaging evidence of lumbar nerve root compression. Arch Phys Med Rehabil 2007; 88(7):840-3. doi: 10.1016/j.apmr.2007.04. 016.
11. Pesonen J, Shacklock M, Suomalainen JS, Karttunen L, Maki J, Airaksinen O, et al. Extending the straight leg raise test for improved clinical evaluation of sciatica: Validity and diagnostic performance with reference to the magnetic resonance imaging. BMC Musculoskelet Disord 2021; 22(1):808. doi: 10.1186/s12891-021-04649-z. Erratum in: BMC Musculoskelet Disord 2021; 22(1):937. doi: 10.1186/ s12891-021-04781-w. Erratum in: BMC Musculoskelet Disord 2022; 23(1):518. doi: 10.1186/s12891-022-05315-8.
12. Qazi SA, Qazi RA, Ahmed T, Rehman L, Javeed F, Aziz HF. The diagnostic accuracy of straight leg raise test in patients more than 60 years of age suffering lumbar disk herniation with low back pain and sciatica. J Neurosci Rural Pract 2023; 14(4):610-4. doi: 10.25259/JNRP_97_2023.
13. Hussein HM, Kamel E, Ragab M, Elerian A. Diagnostic accuracy of the passive straight leg raise test in detecting compression of the lower lumbar nerve roots. Inter J Allied Health Sci Pract 2024; 22(2):8. doi: 10.46743/1540-580X/ 2024.2425.
14. Omar S, Azmat S, Mirza TM, Javed K, Ishtiaq O, Fatima K. Accuracy of straight leg raise test in patients with lumbar disc herniation keeping magnetic resonance imaging as a reference standard. Pak Armed Forces Med J 2016; 66(1): 53-6.
15. Rehman L, Khaleeq S, Hussain A, Ghani E, Mushtaq M, Zaman KU. Correlation between clinical features and magnetic resonance imaging findings in patients with lumbar disc herniation. J Postgrad Med Inst 2007; 21(1).
16. Bashir A, Mehmood N, Patafi MAM, Syed R, Uddin S, Malika. Seated straight leg raise test; sensitivity & specificity in patients with disc herniation at lumbosacral interface using MRI as a gold standard. J Health Rehab Res 2023; 3(2): 976-81. doi: 10.61919/jhrr.v3i2.216.
17. Abo-Elhoda PM, Elsharkawy M, Monir DSM, Elshimy A. Magnetic resonance imaging correlation between lumbar disc herniation and multifidus muscle degeneration. Egypt J Radiol Nuclear Med 2025; 56:87. doi: 10.1186/s43055- 025-01520-2.
18. Segar AH, Baroncini A, Urban JP, Fairbank J, Judge A, McCall I. Obesity increases the odds of intervertebral disc herniation and spinal stenosis; an MRI study of 1634 low back pain patients. Eur Spine J 2024; 33(3):915-23. doi: 10.1007/ s00586-024-08154-4.
19. Azemi ES, Kola I, Kola S, Tanka M. Prevalence of lumbar disk herniation in adult patients with low back pain based in magnetic resonance imaging diagnosis. Open Access Maced J Med Sci 2022; 10(B):1720-5.
20. Pesonen J. Extending the straight leg raise test for improved clinical evaluation of sciatica: From neuromechanical studies to clinical practice. Joensuu and Kupio, Finland: UEF eRepo; 2023. Available from: httpss://urn.fi/URN:ISBN:978-952-61 4794-9.