MRI Bone Texture: A Novel Biomarker for Assessment of Bone Quality and Prediction of Complications in Patients Having Spine Fusion Surgery

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Project Summary Spine fusion surgery is one of the most common, and complex, orthopedic procedures. Complications occur in over 30% of cases, highlighting the need to identify modifiable factors associated with these negative sequelae. Bone quality is a critical determinant of post-operative outcomes, as stability of hardware in bone and de novo bone formation are required for successful fusion. Despite the importance of bone quality to post-operative outcomes, there are limited tools for pre-operative detection of abnormal bone in candidates for fusion. The most common clinical tool for skeletal assessment, dual energy x-ray absorptiometry (DXA), is subject to artifact from spinal abnormalities and infrequently performed for pre-operative evaluation. High resolution peripheral QCT (HRpQCT) can detect pre-operative skeletal abnormalities and predict complications after fusion but is a research tool not available in clinical practice. In contrast, MRI is routinely performed prior to fusion, for diagnosis of spinal disease and surgical planning, making an MRI-based technique ideal to screen for pre-operative skeletal deficits. Our group has recently developed a novel method to evaluate bone quality using standard, clinically acquired MRIs which analyzes the irregularity, or heterogeneity, of trabecular bone texture. In prior work, we found that postmenopausal women with fractures had greater heterogeneity of bone texture than age- matched controls. The proposed study will assess MRI trabecular bone texture as a new technique to detect poor bone quality, predict complications, and track post-operative skeletal changes in patients undergoing spinal fusion. We hypothesize that pre-operative MRI bone texture will relate to volumetric BMD (vBMD) and microarchitecture by HRpQCT and will predict skeletal complications after surgery. Post-operative changes in MRI bone texture will relate to baseline patient characteristics and clinical post-operative treatment regimen, including use of anabolic agents. We will prospectively enroll 100 patients having lumbar spine fusion and follow them for one year. Baseline DXA, HRpQCT, and our MRI-based method will be performed. MRIs will be repeated at 6 months post-operatively to determine whether early changes in MRI bone texture relate to patient characteristics, medication use, and predict complications. CT scans will be performed at one year to assess skeletal complications and completeness of fusion. This proposal aims to: 1) Investigate the relationship between pre-operative MRI bone texture and HRpQCT measurements of vBMD and microarchitecture; 2) Investigate whether MRI bone texture predicts skeletal complications after fusion; 3) Assess longitudinal changes in bone texture and the clinical factors that influence these changes in patients after spine fusion. The long-term goals of our research are to improve identification of patients at high risk for post-operative complications and provide knowledge that will advance future interventional trials. In subsequent work, we plan to extend this technique to other orthopedic populations. Ultimately, we hope to improve the outcomes of patients undergoing fusion and other high-risk orthopedic surgeries by facilitating the creation of new peri-operative treatment paradigms.