BACKGROUND: Failed back surgery syndrome (FBSS) is well known and physicians 
often fear this outcome. Its definition is difficult to understand because it is 
multifactorial. However, we analyze its etiology in order to determine if it is 
from iatrogenic causes. This syndrome can be categorized as follows: mistaken 
diagnoses, transoperative error, technique error, poor application, poor 
indication.
METHODS: We undertook a prospective, observational and lineal study in 20 
patients, 313 surgeries and 4,500 consultations. Age and gender variables were 
analyzed, number of prior surgeries, and diagnosis prior to first surgery, as 
well as predominant symptoms for the last surgery, surgical time, and involved 
segment. Patients were evaluated with Oswestry preoperative scale and followed 
up for 2 years.
RESULTS: There were 16 females and 4 males with an average age of 53.2 years. 
Eight patients had 1 prior surgery, 8 patients had 2 prior surgeries, 3 patients 
had 3 prior surgeries, and 1 patient had 4 prior surgeries. According to the 
Oswestry preoperative scale, 12 patients had scores higher than 60% and at 
2-year follow-up, 11 patients had scores lower than 20%. Despite the persistent 
symptomatology and complications, in almost all patients the satisfaction index 
was 100%. According to the evaluation, the main cause was poor indication in 
three patients, poor indication + technique error in 10, and technique error in 
7 patients.
CONCLUSIONS: The most reported initial etiology was lumbar disc hernia with 
minimally invasive treatment with questionable surgical indication.