Limitations
comorbidity, scoliosis, foraminal stenosis, Foraminal stenosis, radiculopathy, ODI/NRS back pain, listhesis, pain, arthrosis, olisthesis, LSS, stenosis, NRS
DEGENERATION, SCOLIOSIS, CLINICAL SYNDROME, RADICULOPATHY, ARTHROSIS, STENOSIS
The major limitation of this paper is the low number of patients with severe foraminal stenosis in the investigated cohort. Consequently, a warning is in place not to consider our findings as clinical guidelines. Foraminal stenosis was not an inclusion nor exclusion criterion in the NORDSTEN-SST study but an additional radiological finding in a cohort with symptoms of predominantly central LSS. In the present study, we wanted to investigate the treatment of such patients. The question is whether a practice of posterior microsurgical decompression is beneficial for this group. The clinical syndrome of LSS is associated with comorbidity and high age. The practice of performing a simple posterior microsurgical decompression instead of the use of interbody devices, foraminotomy, or far lateral approaches is often tempting but there is a high degree of uncertainty regarding the influence on outcome. We hope that this paper is a start of further studies in this field. Only future investigations will show if the arguments we put forward are legit.We cannot rule out the possibility that patients with severe foraminal stenosis may be associated with more degeneration of the spine and consequently will improve less after surgery, i.e., foraminal stenosis might be confounded by general lumbar degeneration. The analysis was adjusted for several MRI findings but the absence of other markers for degeneration (e.g., facet joint arthrosis) in the analyses might be a source of bias. This might also explain the detection of significant association between severe foraminal stenosis and ODI/NRS back pain while no such association was suggested between foraminal stenosis and NRS leg pain.The MRIs investigated in the present study are acquired in supine position. The size and formation of the neuro-foramina are affected by the weight bearing and load [The investigated cohort are patients with predominantly central LSS and corresponding symptoms. According to the inclusion criteria, patients with one-sided radiculopathy are not included in this study. Consequently, the findings in the present study cannot be generalized to a broader specter of patients with foraminal stenosis but only apply to patients with both LSS and a concurrent foraminal stenosis.The optimal situation would be to include the total of important covariates in the analysis. Albeit, the NORDSTEN data material does not include parameters such as mental status, grade of eventual minimal scoliosis, grade of eventual minimal listhesis, or timespan of symptoms. The inclusion criteria in the present study do however demand a symptom period of minimum 3 months. The exclusion criteria deny patients with a lumbosacral scoliosis of more than 20 degrees verified on AP view or olisthesis of 3 mm or more. However, the impact of mental status, minimal olisthesis, minimal scoliosis, or other non-assessed covariates might influence the results of our analysis. The lack of data regarding any minimal scoliosis and concurrent coupling movements is a major weakness in our analysis with potential mismeasurements of foraminal stenosis.The non-adjusted covariate higher education (y/n) is unequally distributed between the groups with none to moderate and severe foraminal stenosis. Consequently, this is a potential confounding factor in our analysis.Only patients treated with posterior microsurgical decompression were included in this study. The absence of other common decompression techniques, i.e., laminectomy, weakens the external validity of our findings.