title: Fusion mass bone quality after uninstrumented spinal fusion in older patients.
abstract: Older people are at increased risk of non-union after spinal fusion, but little is known about the factors determining the quality of the fusion mass in this patient group. The aim of this study was to investigate fusion mass bone quality after uninstrumented spinal fusion and to evaluate if it could be improved by additional direct current (DC) electrical stimulation. A multicenter RCT compared 40 and 100 μA DC stimulation with a control group of uninstrumented posterolateral fusion in patients older than 60 years. This report comprised 80 patients who underwent DEXA scanning at the 1 year follow-up. The study population consisted of 29 men with a mean age of 72 years (range 62-85) and 51 women with a mean age of 72 years (range 61-84). All patients underwent DEXA scanning of their fusion mass. Fusion rate was assessed at the 2 year follow-up using thin slice CT scanning. DC electrical stimulation did not improve fusion mass bone quality. Smokers had lower fusion mass BMD (0.447 g/cm(2)) compared to non-smokers (0.517 g/cm(2)) (P = 0.086). Women had lower fusion mass BMD (0.460 g/cm(2)) compared to men (0.552 g/cm(2)) (P = 0.057). Using linear regression, fusion mass bone quality, measured as BMD, was significantly influenced by gender, age of the patient, bone density of the remaining part of the lumbar spine, amount of bone graft applied and smoking. Fusion rates in this cohort was 34% in the control group and 33 and 43% in the 40 and 100 μA groups, respectively (not significant). Patients classified as fused after 2 years had significant higher fusion mass BMD at 1 year (0.592 vs. 0.466 g/cm(2), P = 0.0001). Fusion mass bone quality in older patients depends on several factors. Special attention should be given to women with manifest or borderline osteoporosis. Furthermore, bone graft materials with inductive potential might be considered for this patient population.
authors.affiliation: Spine Section, Orthopaedic Research Laboratory, Orthopaedic Department E, Aarhus University Hospital, Building 1A, Nørrebrogade 44, 8000 Aarhus C, Denmark. tba@dadlnet.dk
authors.forename: Thomas
authors.initials: T
authors.lastname: Andersen
authors.forename: Finn B
authors.initials: FB
authors.lastname: Christensen
authors.forename: Bente L
authors.initials: BL
authors.lastname: Langdahl
authors.forename: Carsten
authors.initials: C
authors.lastname: Ernst
authors.forename: Søren
authors.initials: S
authors.lastname: Fruensgaard
authors.forename: Jørgen
authors.initials: J
authors.lastname: Ostergaard
authors.forename: Jens Langer
authors.initials: JL
authors.lastname: Andersen
authors.forename: Sten
authors.initials: S
authors.lastname: Rasmussen
authors.forename: Bent
authors.initials: B
authors.lastname: Niedermann
authors.forename: Kristian
authors.initials: K
authors.lastname: Høy
authors.forename: Peter
authors.initials: P
authors.lastname: Helmig
authors.forename: Randi
authors.initials: R
authors.lastname: Holm
authors.forename: Bent Erling
authors.initials: BE
authors.lastname: Lindblad
authors.forename: Ebbe Stender
authors.initials: ES
authors.lastname: Hansen
authors.forename: Niels
authors.initials: N
authors.lastname: Egund
authors.forename: Cody
authors.initials: C
authors.lastname: Bünger
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D003131:Combined Modality Therapy; D004599:Electric Stimulation Therapy; D005260:Female; D006801:Humans; D016014:Linear Models; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D013123:Spinal Fusion; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000628:therapy*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome