STUDY DESIGN: A case of acute low back pain caused by pseudogout attack of the lumbar facet joint is reported. OBJECTIVE: To report a new cause of acute low back pain previously unreported in the literature. SUMMARY OF BACKGROUND DATA: There have been some reports of lumbar spinal stenosis caused by calcium pyrophosphate dihydrate crystal deposition. However, there are no known reports of pseudogout attack of the lumbar facet joint. METHODS: An axial magnetic resonance imaging scan demonstrated joint effusion at the level of the bilateral L4-L5 facet joint. Aspiration of the left L4-L5 facet joint yielded 1.5 mL of pus-like synovial effusion. Multiple cultures of synovial fluid tested negative for bacteria and fungi, whereas compensated polarized light microscopy revealed monoclinic or triclinic crystals with a positive birefringence. RESULTS: The symptoms of acute low back pain lasted for 3 days. Local and systemic inflammatory signs, as well as symptoms, gradually improved after joint aspiration. A follow-up evaluation 8 months after lumbar facet joint aspiration showed complete resolution of pain and no neurologic deficit. CONCLUSIONS: Pseudogout attack of the lumbar facet joint is rare, but this clinical entity should be added to the differential diagnosis of acute low back pain.
STUDY DESIGN: A case of acute low back pain caused by pseudogout attack of the lumbar facet joint is reported. OBJECTIVE: To report a new cause of acute low back pain previously unreported in the literature. SUMMARY OF BACKGROUND DATA: There have been some reports of lumbar spinal stenosis caused by calcium pyrophosphate dihydrate crystal deposition. However, there are no known reports of pseudogout attack of the lumbar facet joint. METHODS: An axial magnetic resonance imaging scan demonstrated joint effusion at the level of the bilateral L4-L5 facet joint. Aspiration of the left L4-L5 facet joint yielded 1.5 mL of pus-like synovial effusion. Multiple cultures of synovial fluid tested negative for bacteria and fungi, whereas compensated polarized light microscopy revealed monoclinic or triclinic crystals with a positive birefringence. RESULTS: The symptoms of acute low back pain lasted for 3 days. Local and systemic inflammatory signs, as well as symptoms, gradually improved after joint aspiration. A follow-up evaluation 8 months after lumbar facet joint aspiration showed complete resolution of pain and no neurologic deficit. CONCLUSIONS: Pseudogout attack of the lumbar facet joint is rare, but this clinical entity should be added to the differential diagnosis of acute low back pain.