Link Between Lumbar Modic Changes and Low Back Symptoms
Link Between Lumbar Modic Changes and Low Back Symptoms
The study population was selected from consecutive LBP patients (n = 4380) with or without radicular symptoms who were referred initially for standard lumbar spine MRI to the Departments of Orthopaedics, Rheumatology or Physical and Rehabilitation Medicine at the region of Helsinki University Hospital during 2003–2007. Images from all patients examined by MRI were analysed monthly, and eligible patients were identified by an experienced radiologist. The inclusion criteria were chronic nonspecific LBP of at least three-month duration and lumbar M1 or mixed M1/M2. All included patients gave written informed consent to use their clinical data for study purposes. The study protocol was approved by the Ethics Committee of Helsinki and the Uudenmaa District University Hospitals.
The exclusion criteria were age ≥ 65 y; specific back disease, such as fracture, neoplasia, infectious, or rheumatic spine disease; spondylolisthesis (≥4 mm); spinal stenosis; disc extrusion; any other finding with even the slightest neural compression; minor spine operation, such as herniated disc surgery within the past six months; and major spine operation, such as fusion or disc prosthesis at any time. Annular tears, bulging of the disc, and facet joint degeneration were not exclusion criteria, since these changes are often found in association with disc degeneration and also with MC. When there was uncertainty about the etiology of signal abnormalities, we checked laboratory results and other clinical findings to exclude specific causes (e.g., infectious or rheumatic spinal disease).
Within 1–3 weeks of identification, eligible patients were contacted by telephone to complete questionnaires to describe average LBP intensity during the past week (scale 0–10; 0 = no pain, 10 = worst pain possible) and obtain the Oswestry Disability Index (ODI, version 1.0; scale 0–100%: 0% = no disability, 100% = very severe disability). ODI was obtained by a patient-completed questionnaire that generates a subjective percentage score of level of function (disability) in activities of daily living among back pain sufferers. The time interval between baseline MRI and symptom assessment varied from two to six weeks. Standard lumbar spine MRI was performed again at the two-year follow-up visit, 23–25 months after baseline imaging. Questionnaires for average LBP intensity and ODI were completed during the follow-up visit.
The MRI studies at baseline were performed with two 1.0 T (Gyroscan Intera, Philips Medical Systems, Eindhoven, The Netherlands) and three 1.5 T (Signa HD, GE Healthcare, Milwaukee, WI, USA and Sonata and Symphony, Siemens Medical, Erlangen, Germany) units using the established spine imaging protocols of the participating hospitals. The imaging parameters of T1- and T2-weighted turbo spin-echo (TSE) or fast spin-echo (FSE) sequences were conventional: for example, 13 ms TE and 600 ms TR (short TE and TR) for T1w and 115 ms TE and 4000 ms TR (long TE and TR) for T2w. At follow-up, all MRI images were obtained with a 1.0 T unit (Gyroscan Intera, Philips Medical Systems), following a uniform protocol.
Evaluations of the baseline and two-year follow-up images were performed by visually examining hard copies of sagittal T1WIs and T2WIs. We chose visual analysis of hard copies for uniformity of assessments, as all participating hospitals did not have digital picture archiving and communication systems (PACS) at the beginning of data collection. All images were assessed by a fellow in musculoskeletal radiology (JJ) who was blinded to the patients' symptoms. To estimate the interobserver reliability, an experienced musculoskeletal radiologist (JN) evaluated images of 30 endplates from randomly selected patients.
Each patient's baseline and follow-up MR images were assessed on an x-ray light box, starting with the baseline images. Removal of imaging dates during evaluation of the images was not considered necessary, because the reader was blinded to clinical data. The relative size in percentages (intervals of 5%) of each MC compared to corresponding vertebra in sagittal images was estimated as the average of assessments of three slices (midsagittal and left and right quarter) from T2w. Next, the proportions (%) of M1 and M2 within the MC were estimated from three slices (middle and left and right quarter) covering MC of sagittal T1w and T2w.
Descriptive statistics were calculated to describe the data. Reader reliability was assessed using intraclass correlation coefficients (ICC; absolute agreement). ICC can be interpreted as follows: < 0.40% poor, 0.40–0.59 fair, 0.60–0.74 good, and 0.75–1.00 excellent. Limits of agreement were also calculated. The extent of M1 and M2 at baseline and follow-up were calculated by multiplying the size of MC at both endplates by the corresponding proportions of M1 and M2, respectively, and summing up the products of both endplates. Only M1 and M2 were used in the analyses, due to the low prevalence of M3 (Table 1). Changes in the extent of M1 and M2 over the follow-up were calculated, as well as changes in low back symptoms. Linear regression analysis was used to evaluate the association between changes in the extent of M1 and M2 and low back symptoms, both unadjusted and adjusted for age, gender, and size of MC at baseline. IBM SPSS Statistics version 22 was used in the analyses.
Methods
Study Population
The study population was selected from consecutive LBP patients (n = 4380) with or without radicular symptoms who were referred initially for standard lumbar spine MRI to the Departments of Orthopaedics, Rheumatology or Physical and Rehabilitation Medicine at the region of Helsinki University Hospital during 2003–2007. Images from all patients examined by MRI were analysed monthly, and eligible patients were identified by an experienced radiologist. The inclusion criteria were chronic nonspecific LBP of at least three-month duration and lumbar M1 or mixed M1/M2. All included patients gave written informed consent to use their clinical data for study purposes. The study protocol was approved by the Ethics Committee of Helsinki and the Uudenmaa District University Hospitals.
The exclusion criteria were age ≥ 65 y; specific back disease, such as fracture, neoplasia, infectious, or rheumatic spine disease; spondylolisthesis (≥4 mm); spinal stenosis; disc extrusion; any other finding with even the slightest neural compression; minor spine operation, such as herniated disc surgery within the past six months; and major spine operation, such as fusion or disc prosthesis at any time. Annular tears, bulging of the disc, and facet joint degeneration were not exclusion criteria, since these changes are often found in association with disc degeneration and also with MC. When there was uncertainty about the etiology of signal abnormalities, we checked laboratory results and other clinical findings to exclude specific causes (e.g., infectious or rheumatic spinal disease).
Within 1–3 weeks of identification, eligible patients were contacted by telephone to complete questionnaires to describe average LBP intensity during the past week (scale 0–10; 0 = no pain, 10 = worst pain possible) and obtain the Oswestry Disability Index (ODI, version 1.0; scale 0–100%: 0% = no disability, 100% = very severe disability). ODI was obtained by a patient-completed questionnaire that generates a subjective percentage score of level of function (disability) in activities of daily living among back pain sufferers. The time interval between baseline MRI and symptom assessment varied from two to six weeks. Standard lumbar spine MRI was performed again at the two-year follow-up visit, 23–25 months after baseline imaging. Questionnaires for average LBP intensity and ODI were completed during the follow-up visit.
Imaging Methods
The MRI studies at baseline were performed with two 1.0 T (Gyroscan Intera, Philips Medical Systems, Eindhoven, The Netherlands) and three 1.5 T (Signa HD, GE Healthcare, Milwaukee, WI, USA and Sonata and Symphony, Siemens Medical, Erlangen, Germany) units using the established spine imaging protocols of the participating hospitals. The imaging parameters of T1- and T2-weighted turbo spin-echo (TSE) or fast spin-echo (FSE) sequences were conventional: for example, 13 ms TE and 600 ms TR (short TE and TR) for T1w and 115 ms TE and 4000 ms TR (long TE and TR) for T2w. At follow-up, all MRI images were obtained with a 1.0 T unit (Gyroscan Intera, Philips Medical Systems), following a uniform protocol.
Image Analysis
Evaluations of the baseline and two-year follow-up images were performed by visually examining hard copies of sagittal T1WIs and T2WIs. We chose visual analysis of hard copies for uniformity of assessments, as all participating hospitals did not have digital picture archiving and communication systems (PACS) at the beginning of data collection. All images were assessed by a fellow in musculoskeletal radiology (JJ) who was blinded to the patients' symptoms. To estimate the interobserver reliability, an experienced musculoskeletal radiologist (JN) evaluated images of 30 endplates from randomly selected patients.
Each patient's baseline and follow-up MR images were assessed on an x-ray light box, starting with the baseline images. Removal of imaging dates during evaluation of the images was not considered necessary, because the reader was blinded to clinical data. The relative size in percentages (intervals of 5%) of each MC compared to corresponding vertebra in sagittal images was estimated as the average of assessments of three slices (midsagittal and left and right quarter) from T2w. Next, the proportions (%) of M1 and M2 within the MC were estimated from three slices (middle and left and right quarter) covering MC of sagittal T1w and T2w.
Statistical Analysis
Descriptive statistics were calculated to describe the data. Reader reliability was assessed using intraclass correlation coefficients (ICC; absolute agreement). ICC can be interpreted as follows: < 0.40% poor, 0.40–0.59 fair, 0.60–0.74 good, and 0.75–1.00 excellent. Limits of agreement were also calculated. The extent of M1 and M2 at baseline and follow-up were calculated by multiplying the size of MC at both endplates by the corresponding proportions of M1 and M2, respectively, and summing up the products of both endplates. Only M1 and M2 were used in the analyses, due to the low prevalence of M3 (Table 1). Changes in the extent of M1 and M2 over the follow-up were calculated, as well as changes in low back symptoms. Linear regression analysis was used to evaluate the association between changes in the extent of M1 and M2 and low back symptoms, both unadjusted and adjusted for age, gender, and size of MC at baseline. IBM SPSS Statistics version 22 was used in the analyses.
Source...