From December 2010 to June 2011 , 65 patients with acute low back pain without sciatica due to lumbar disc herniation or bulging confirmed by CT or MRI were randomly divided into sacral canal injection group ( experimental group ) and lumbar oblique wrench group ( control group ) : the experimental group had 35 cases , including 30 males and 5 females , with an average age of ( 43.90 + / - 1.14 ) years old ranging from 33 to 56 years old .