Lumbar Disc Herniation
Lumbar disc herniation is a displacement of disc material which then presses on nerves. The occurrence of disc herniation is rare (1 – 5%) compared to mechanical low back pain. Symptoms of disc herniation include: leg pain, numbness, tingling, weakness, or increased symptoms with coughing, sneezing or straining. It’s found mainly among people age 30 to 50 with predominance among males (2:1). Risk factors for disc herniation include smoking (3x), weight bearing sports, and certain work activities such as repetitive lifting. Disc injuries occur from lifting, bending and twisting. There is recent evidence that there is a genetic predisposition and it may have more of an influence on disc herniations than was previously thought, as compared to physical load. Improvements are usually seen in most disc patients after conservative (non-surgical) care: soft tissue therapy, spinal manipulation, traction, electrotherapy, exercises, rest, ice and medication. Only 10% of people will continue to have significant pain after 6 weeks and may require surgery.
Approximately 25% of people under 60 will have a disc herniation (seen on MRI) without any symptoms. Hence, all leg discomfort (sciatica) is not caused by a disc herniation and can be attributed to other sources. Similarly, all disc herniations found by imaging (CT, MRI) are not necessarily what is creating your leg symptoms. Therefore, it is best to be thoroughly examined in order to determine the exact cause of your symptoms in order to formulate the appropriate treatment plan for your low back injury.
Studies (Nachemson, 1964 and Wilke et al, 1999) measured lumbar intervertebral disc pressures during different postures and activities. Lying down puts considerably less (1/5) pressure on one’s disc compared to standing. Leaning forward while sitting or standing substantially increases disc pressure. Lifting with knees bent and a straight back produces less pressure than lifting with your legs straight in a bent over posture. Holding a load close to your body also reduces pressure on the discs.
Position Pressure (MPa)
Lying supine - 0.10
Lying on the side - 0.12
Sitting actively straightening the back - 0.55
Sitting with maximum flexion (tying shoes) - 0.83
Sitting slouched into the chair - 0.27
Relaxed standing - 0.50
Standing, bent forward - 1.10
Lifting 20 kg, bent over posture, legs straight - 2.30
Lifting 20 kg knees bent up right posture - 1.70
Holding 20 kg close to the body - 1.10
New In Vivo Measurements of Pressures in the Intervertebral Disc in Daily Life
SPINE Volume 24, Number 8, 1999, pp 755–762