Epidemiology Low back pain affects 50-80% of population in lifetime $100 billion in annual cost second only to respiratory infection as cause to visit doctors 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 user, h/o of fever and chills) tumor (h/o or cancer) trauma (h/o 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 activity such as lifting objects and prolonged standing sacroiliac symptoms pain originating from sacroiliac joint peripheral / neurogenic radicular pain unilateral leg pain usually dermatomal referred pain buttocks posterior thighs inguinal region (think L5-S1) neurogenic claudication pain in buttock and legs that is worse with prolonged standing fairly specific for spinal stenosis myelopathy clumsiness in hands gait instability due to injury of spinal cord (~ L1 or above) conus medullaris syndrome cauda equina syndrome bilateral leg pain LE weakness saddle anesthesia bowel/bladder symptoms spinal cord injury incomplete complete Wadell Signs system to evaluate 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 which do not follow dermatomal pattern overreaction to physical examination Imaging Radiographs indications for radiographs pain lasting > one month and not responding to not nonoperative management red flags are present MRI highly sensitive and specific high rate of abnormal findings on MRI in normal people Positive MRI Findings in Asymptomatic Patients Age % 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 comression fracture trauma Low back pain muscles strain disc herniation / discogenic pain degenerative spondylolithesis spinal stenosis lumbar radiculopathy abdominal aortic aneurism Sacroiliac pain SI infection ankylosing spondylitis Sacral pain coccydynia sacral insufficiency fracture Treatment Treatment dictated by cause of pain.