Introduction: Although degenerative disc disease (DDD) has been associated with chronic low-back pain it is often challenging to determine with precision, in each individual case the exact etiology of the pain. Up to now, there is no standard therapeutic guidelines for indicating lumbar fusion in the setting of DDD.

Methods: The authors performed a retrospective chart review of MRi findings (such as the presence of Modic changes and the degree of disc degeneration) and Bone-scan (Scintigraphy) of patients with DDD who underwent anterior lumbar inter body fusion at a single tertiary care hospital from 2007-2010. The results were compared with the clinical outcomes (ODI and VAS) at four standard post-operative follow-up time points: 6 weeks, 3 months, 6 months, and 1 year post-operatively

Results: The strongest predictor of post-operative clinical outcomes (p<0.05), as measured by the estimated marginal means of VAS-back pain and ODI was achieved by combining all the three preoperative variables under study (presence of DDD, presence Modic changes and Bone-Scan positivity) in a composed score which has been named Lumbar Fusion Outcome Score (LUFOS). Variables which have been shown to be significantly associated with low-back pain in previous studies (such as age, smoking status and Bone Mass Index - BMI) were also evaluated regarding their possible effects upon outcomes. According to the Mixed Effect model such grading system was very powerful in its capacity of preoperatively classifying patients in two different groups (Surgical: LUFOS 0 and 1 and Nonsurgical: LUFOS 2 and 3). According to the performed statistical tests both groups presented significantly different clinical outcomes beginning at three months up to one year of follow-up.

Conclusions: The authors successfully developed a surgically-oriented grading system for DDD with basis on pre-operative parameters from MRi and Bone-Scan (Scintigraphy) which has been shown to be highly predictable of long-term clinical outcomes.

Patient Care: A grading system capable of predicting long-term clinical outcomes after lumbar fusion for patients with degenerative disc disease constitutes a major development which is expected to help clinicians to better select those patients which should receive surgical intervention. Moreover, as low-back pain represents one of the major burdens of the current health system, such new classification is also expected to provide a major socioeconomic impact.

Learning Objectives: - To understand the current level of evidence of the relation between degenerative disc disease and low-back pain - To understand the radiological and epidemiological factors which have been proposed as possible pre-operative indicators for selecting patients for fusion in the setting of degenerative disc disease - To understand the components of the new classification system and the possible socioeconomic impact of a grading system capable of predicting successful post-operative clinical outcomes after lumbar fusion in the setting of degenerative disc disease

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