To evaluate the correlation between preoperative radiologic degree and the postoperative prognosis in lumbar foraminal stenosis (LFS) patients who required decompression. There have been only a few studies for postoperative prognosis according to the degree of preoperative stenosis in patients requiring surgery. The shape and severity of LFS was classified according to Lee et al’s classification. Radiating leg pain was assessed preoperatively and at the last follow-up. Oswestry Disability Index (ODI), Roland Morris Disability Questionnaire (RMDQ), SF-36 Physical Component Score (PCS), and SF-36 Mental Component Score (MCS) were surveyed at the last follow-up. Mean follow-up was 6.3 years.

Among 130 patients, 34 cases were classified as Grade 1T (transverse), 31 cases as Grade 1V (vertical), 32 cases as Grade 2, and 33 cases as Grade 3. The mean age was 65.0 years. Radiating leg pain (Visual Analogue Scale) preoperatively and lastly was 6.8 and 2.3, respectively in Grade 1T; 7.4 and 3.3, respectively in Grade 1V; 7.7 and 3.0, respectively in Grade 2; and 7.4 and 2.9, respectively in Grade 3. ODI and RMDQ at the last follow-up were 13.9 and 6.3, respectively in Grade 1T; 23.1 and 11.2, respectively in Grade 1V; 18.8 and 12.3, respectively in Grade 2; 21.6 and 11.7, respectively in Grade 3. Grade 1T had significantly lower value than Grade 1V, 2 and 3 in ODI and RMDQ, respectively. SF-36 PCS and MCS at the last follow-up were 62.2 and 70.5, respectively in Grade 1T; 33.7 and 40.3, respectively in Grade 1V; 42.1 and 48.2, respectively in Grade 2; 37.0 and 48.5, respectively in Grade 3. Grade 1T had significantly higher value than grade 1V, 2 and 3 in SF-36 PCS and MCS, respectively.

Decompression for LFS was effective for reducing leg radiating pain. Functional outcome and quality of life was better in mild transverse type implying the role of dorsal root ganglion and dynamic stenosis.