P16. Uninstrumented laminectomy inadequately addresses foraminal stenosis compared to lumbar interbody fusion: an anatomic study based on CT scans

BACKGROUND CONTEXT Foraminal stenosis with accompanying radicular symptoms is a common cause of leg pain in older adults. Operative treatment of radiculopathy can involve either direct decompression via laminectomy or foraminotomy or indirect decompression with lumbar interbody fusion. We sought to evaluate the anatomic effects of each of these techniques on foraminal dimensions using computer tomography imaging. PURPOSE To determine if use of an interbody device in conjunction with fusion will confer greater improvement in foraminal dimensions compared to those who undergo laminectomy alone. STUDY DESIGN/SETTING Retrospective comparative cohort review at a large academic institution. PATIENT SAMPLE We evaluated patients over 18 years of age that underwent primary 1-3 level uninstrumented laminectomy and 1-2 level ALIF or TLIF with both preoperative and postoperative CT scans within 1-year of the surgery. There were a total of 64 patients, with a total of 76 operative levels and 152 vertebral foramina. Fourteen patients had undergone laminectomy alone, and 50 patients underwent lumbar interbody fusion (ALIF:26;TLIF:24). OUTCOME MEASURES Computer tomography radiographic dimensions of foramina stenosis. METHODS Measurements of foramen were conducted bilaterally at the operative level in the sagittal plane. Foraminal height, width and total area were measured at the cut with the most foraminal stenosis present. Hemilaminectomies were excluded. Independent-samples T-test and Pearson Chi-square analysis were performed for the cohort; significant set at p<0.05. RESULTS There were a total of 64 patients, with a total of 76 operative levels and 152 vertebral foramina. Fourteen patients had undergone laminectomy alone, and 50 patients underwent lumbar interbody fusion (ALIF:26;TLIF:24). Age was observed to be higher in patients that underwent laminectomy versus TLIF and ALIF (66.0±8.0 years vs 60.4±12.8 years and 55.8±12.2 years, respectively, p=0.02). Other demographic differences were similar between cohorts (p>0.05). Preoperative foraminal width, height, and area were similar between cohorts (p>0.05); however, postoperative foraminal heights were different among groups. Both TLIF and ALIF had greater percent increases in foraminal height (48% and 41%) and area (65% and 55%) compared to laminectomy (height: 8.7%, area: 6.1%, p=0.001). CONCLUSIONS Patients that underwent laminectomy had similar improvement in foraminal width, but significantly lower increases in foraminal height and area compared to those that underwent anterior or transforaminal interbody fusions. This supports the idea that laminectomies alone are insufficient for the treatment of isolated foraminal stenosis. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs. Foraminal stenosis with accompanying radicular symptoms is a common cause of leg pain in older adults. Operative treatment of radiculopathy can involve either direct decompression via laminectomy or foraminotomy or indirect decompression with lumbar interbody fusion. We sought to evaluate the anatomic effects of each of these techniques on foraminal dimensions using computer tomography imaging. To determine if use of an interbody device in conjunction with fusion will confer greater improvement in foraminal dimensions compared to those who undergo laminectomy alone. Retrospective comparative cohort review at a large academic institution. We evaluated patients over 18 years of age that underwent primary 1-3 level uninstrumented laminectomy and 1-2 level ALIF or TLIF with both preoperative and postoperative CT scans within 1-year of the surgery. There were a total of 64 patients, with a total of 76 operative levels and 152 vertebral foramina. Fourteen patients had undergone laminectomy alone, and 50 patients underwent lumbar interbody fusion (ALIF:26;TLIF:24). Computer tomography radiographic dimensions of foramina stenosis. Measurements of foramen were conducted bilaterally at the operative level in the sagittal plane. Foraminal height, width and total area were measured at the cut with the most foraminal stenosis present. Hemilaminectomies were excluded. Independent-samples T-test and Pearson Chi-square analysis were performed for the cohort; significant set at p<0.05. There were a total of 64 patients, with a total of 76 operative levels and 152 vertebral foramina. Fourteen patients had undergone laminectomy alone, and 50 patients underwent lumbar interbody fusion (ALIF:26;TLIF:24). Age was observed to be higher in patients that underwent laminectomy versus TLIF and ALIF (66.0±8.0 years vs 60.4±12.8 years and 55.8±12.2 years, respectively, p=0.02). Other demographic differences were similar between cohorts (p>0.05). Preoperative foraminal width, height, and area were similar between cohorts (p>0.05); however, postoperative foraminal heights were different among groups. Both TLIF and ALIF had greater percent increases in foraminal height (48% and 41%) and area (65% and 55%) compared to laminectomy (height: 8.7%, area: 6.1%, p=0.001). Patients that underwent laminectomy had similar improvement in foraminal width, but significantly lower increases in foraminal height and area compared to those that underwent anterior or transforaminal interbody fusions. This supports the idea that laminectomies alone are insufficient for the treatment of isolated foraminal stenosis.