How often is low back pain not coming from the back?

STUDY DESIGN Consecutive case series cohort. OBJECTIVE To determine the relative frequencies of the spine, the sacroiliac (SI) joint, and the hip joint being the primary pain generator among patients presenting at a spine surgery clinic for low back pain (LBP). SUMMARY OF BACKGROUND DATA Identification of the primary pain generator in a patient with LBP is difficult. Possible pain sources include the lumbar spine, the SI joint, and the hip joint. Their relative frequencies among patients presenting at a spine surgeon's clinic have not been well established. METHODS Three hundred sixty-eight new patients were seen at a single spine surgeon's clinic during a 10-month period. Of these, 289 (78.5%) complained primarily of LBP with or without leg pain. Seventy-seven had previous surgery. The remaining 200 cases were reviewed for all diagnostic tests performed, as well as the final diagnosis. RESULTS One hundred sixty-four (82%) had spine pathology, but only 130 (65%) had spine-only pathology, whereas 35 (17.5%) had a combination of spine plus hip and/or SI joint pathology. An additional 16 (8%) had hip and/or SI joint pathology without spine pathology. Twenty (10%) had an undefined pain source. Overall, 25 (12.5%) had hip pathology, and 29 (14.5%) had SI joint pathology. CONCLUSION For patients presenting to a spine surgeon's clinic for LBP, up to 25% of patients may have significant pain contribution from the hip or SI joints, and an additional 10% will still have an undefined pain source even after diagnostic workup. This underscores the need for clinicians to be aware of nonspinal pain generators and to appropriately pursue alternative diagnoses.