Instability in the Lumbar Spine of Patients With Age Related Changes and Narrowing of the Spinal Canal (Spinal Stenosis)

A multicenter retrospective cohort study of prospectively collected data from national spine surgery databases in Denmark and Sweden. This project is a collaboration between sector for spine surgery and research Middelfart Hospital and spine surgeons at Orebro Hospital and Lund Hospital in Sweden. Data subtracted from Danish national spine surgery database, DaneSpine, from Middelfart Hospital, and Swedish Spinal Register, SweSpine, from hospitals in Malmö, Lund, Trelleborg and Karlskroga. Both databases are clinical quality databases with a high response-rate. DaneSpine is administered by Danish Society of Spine Surgeons and is managed by secretary of DaneSpine. SweSpine is administered by Swedish Society of Spinal Surgeons and managed Patients are invited to register when scheduled for surgery. Patients signs informed consent and receives follow-up questionaires 3 and 6 months, one, two, 5 and 10 years post-surgery. Questionaires are validated PROM (patient reported outcome measures) and PREM (patient reported experience measures). The surgeon is responsible for registering surgical data, including complications and reoperations. Data relevant for present study will be applied for at the respective societies and managed and stored in compliance with General Data Protection Regulation. The EasyWiz software (Medical Insight, Chicago, IL, USA) is used for analysis of all MRIs and radiographs. All imaging will be analyzed by 2 independent examiners. The interobserver reliability will be calculated. Missing data such as variables reported as missing or non-reported will not be included in statistical analysis. Statistics: significance of difference in mean values between groups for continuous normally distributed data unpaired t-test. Categorical variables normally distributed: Chi-squared/Fishers exact test. Multivariable regression analysis. Kappa statistics for interobserver reliability presented in the article.