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The article presents a college thesis which investigated the determinants of the outcomes of lumbar spinal stenosis surgery and is based on several papers previously published by F. G. Sigmundsson, B. Jönsson and B.Strömqvist, including papers which appeared in a 2013 issue of "Acta Orthopaedica", a 2012 issue of "Acta Orthopaedica" and a 2014 issue of "Spine".

Background and purpose Modular cementless revision prostheses are being used with increasing frequency. In this paper, we review risk factors for the outcome of the Link MP stem and report implant survival compared to conventional cemented long-stem hip revision arthroplasties. Patients and methods We used data recorded in the Swedish Hip Arthroplasty Register. 812 consecutive revisions with the MP stem (mean follow-up time 3.4 years) and a control group with 1,073 cemented long stems (mean follow-up time 4.2 years) were included. Kaplan-Meier analysis was used to determine implant survival. The Cox regression model was used to study risk factors for reoperation and revision. Results The mean age at revision surgery for the MP stem was 72 (SD 11) years. Decreasing age (HR == 1.1, 95% CI: 1--1.1), multiple previous revisions (HR == 2.6, 95% CI: 1.1--6.2), short stem length (HR == 2.4, 95% CI: 1.1--5.2), standard neck offset (HR == 5, 95% CI: 1.5--17) and short head-neck length (HR == 5.3, 95% CI 1.4--21) were risk factors for reoperation. There was an overall increased risk of reoperation (HR == 1.7, 95% CI: 1.3--2.4) and revision (HR == 1.9, 95% CI: 1.2--3.1) for the MP prostheses compared to the controls. Interpretation The cumulative survival with both reoperation and revision as the endpoint was better for the cemented stems with up to 3 years of follow-up. Thereafter, the survival curves converged, mainly because of increasing incidence of revision due to loosening in the cemented group. We recommend the use of cemented long stems in patients with limited bone loss and in older patients. [ABSTRACT FROM AUTHOR]