Table 1.

Selection Criteria of Patients.

Inclusion	Exclusion
Age between 18 and 65 years	History of previous lumbar spine surgery
LBP a lasting more than 3 months	Chemotherapy or pulse therapy with corticoids
MRI b performed less than 6 months before surgery	History of spinal infection
Failure of conservative treatment for at least 6 weeks	Previous intradiscal therapies

^a—Low back pain; ^b—Magnetic resonance imaging.