Epidemiology Low back pain affects 50-80% of the population during their lifetime $100 billion annual cost secondary only to respiratory infections as a reason for visiting a doctor's office Etiology Mechanism muscle strain most common cause of low back pain most common degenerative disorders lumbar spinal stenosis lumbar disc herniation discogenic back pain Risk factors obesity, smoking, gender lifting, vibration, prolonged sitting job dissatisfaction Red flags infection (IV drug use, history of fever and chills) tumor (history of cancer) trauma (history of car accident or fall) cauda equina syndrome (bowel/bladder changes) Outcomes 90% of low back pain resolves within one year Presentation Symptoms axial pain musculogenic most common cause of back pain associated with activity characterized by stiffness and difficulty bending discogenic pain controversial confirmed by discogram mechanical pain caused by facet degeneration micro- and macro-instability worse with activities such as lifting objects and prolonged standing sacroiliac symptoms pain originating from a sacroiliac joint peripheral / neurogenic radicular pain unilateral leg pain usually dermatomal referred pain buttocks posterior thighs inguinal region (L5-S1) neurogenic claudication pain in buttocks and legs that is worse with prolonged standing fairly specific for spinal stenosis myelopathy hand clumsiness gait instability due to spinal cord injury (~L1 or above) conus medullaris syndrome cauda equina syndrome bilateral leg pain LE weakness saddle anesthesia bowel/bladder symptoms spinal cord injury incomplete complete Waddell signs evaluation of non-organic back pain symptoms clinically significant if three positive signs are present: superficial and non-anatomic tenderness pain with axial compression or simulated rotation of the spine negative straight-leg raise with patient distraction regional disturbances that do not follow dermatomal patterns overreaction to physical examination Imaging Radiographs indications pain lasting >1 month and not responsive to nonoperative management red flags MRI highly sensitive and specific high rate of abnormal findings in asymptomatic individuals Positive MRI Findings in Asymptomatic Patients Age (y/o) % HNP % Disc Bulge % Degeneration 20-39 21 56 34 40-59 22 50 59 60-79 36 79 93 Differential Neck and arm pain trauma cervical spondylosis metastatic disease / infection cervical radiculopathy cervical myelopathy ankylosing spondylitis Thoracic back and rib pain trauma metastatic disease / infection thoracic disc herniation osteoporotic compression fracture trauma Low back pain muscle strain disc herniation / discogenic pain degenerative spondylolisthesis spinal stenosis lumbar radiculopathy abdominal aortic aneurysm Sacroiliac pain SI infection ankylosing spondylitis Sacral pain coccydynia sacral insufficiency fracture Treatment dictated by the cause of pain