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

The relationship between contrast ratio of bone marrow edema on MRI and exercise prohibition period in lumbar spondylolysis patients (#14)

Reo Asai 1 2 , Masaki Tatsumura 3 , Satoshi Matsuura 3 , Katsuya Nagashima 3 , Yousuke Takeuchi 3 , Toru Funayama 1 , Masashi Yamazaki 1
  1. Department of Orthopaedic Surgery, Institute of Medicine, University of Tsukuba, Tsukuba, IBARAKI, Japan
  2. Department of Orthopaedic Surgery, Tokyo Medical University Ibaraki Medical Center, Ami, IBARAKI, Japan
  3. Department of Orthopaedic Surgery and Sports Medicine, Tsukuba University Hospital Mito Clinical Education and Training Center, Mito Kyodo General Hospital, Mito, IBARAKI, Japan

INTRODUCTION

Acute-phase lumbar spondylolysis with bone marrow edema is treated conservatively. The required exercise prohibition period until the achievement of bone union differs greatly in each patient. However, few studies have investigated quantitative measurements or formulas for predicting the exercise prohibition period in each patient. This study aimed to quantify bone marrow edema on magnetic resonance imaging (MRI) in patients with lumbar spondylolysis using the contrast ratio (CR) and investigate its association with the exercise prohibition period.

 

METHODS

Patients diagnosed with lumbar spondylolysis at a single vertebral level at our institute between 2014 and 2019 were included in this study. Conservative therapy included exercise prohibition and the use of a semi-rigid lumbosacral brace until the disappearance of bone marrow edema on monthly MRI. Patients older than 18 years or those who did not achieve bone union were excluded from the study. A total of 92 patients (62 unilateral and 30 bilateral) were included in this study. Age, sex, affected lumbar level, and exercise prohibition period were collected for each patient. Computed tomography (CT) horizontal stage and CR of bone marrow edema on MRI were investigated for each lesion. Multiple regression analysis was performed, with the exercise prohibition period as the objective variable and all other items as explanatory variables. Note that the lesion with higher CR was defined as the main lesion and the explanatory variables of CT stage and CR were separated as main and contralateral variables. The CR and CT stage of the contralateral lesion in unilateral cases was set to zero and none, respectively. Variables were selected using the stepwise method.

 

RESULTS

The average age was 14.2 years, 74 patients were male and 18 were female. The affected levels were L3 in 11 patients, L4 in 19 patients, and L5 in 62 patients. The average exercise prohibition period was 76.4 days in unilateral patients and 91.7 days in bilateral patients, respectively. The CT horizontal stage was pre-lysis stage in 27, early stage in 52, and progressive stage in 13 of the main lesions, while pre-lysis stage in 8, early stage in 15, and progressive stage in 7 of the contralateral lesions (only in bilateral cases). The average CR of the main lesion was 0.280 in unilateral cases and 0.328 in bilateral cases, whereas the average CR of the contralateral lesion was 0.219 (only in bilateral cases). Multiple regression analysis revealed that the exercise prohibition period was associated with CR of the main side (p<0.001) and contralateral side (p=0.041).

 

DISCUSSION

In this study, CR of the bone marrow edema on MRI was associated with the exercise prohibition period, suggesting that CR may be a useful indicator in patients with lumbar spondylolysis. Previous studies have revealed that patients with progressive CT stages require longer exercise prohibition periods. In this study, however, CT stages were not associated in the multiple regression analysis, suggesting that quantitative assessment of the lesion using CR may be more useful than qualitative assessment using CT stage in predicting the exercise prohibition period.