Acta Orthopaedica 2009; 80 (4): 445–450 445 Impact of instrumentation in lumbar spinal fusion in elderly patients 71 patients followed for 2–7 years Thomas Andersen, Finn B Christensen, Bent Niedermann, Peter Helmig, Kristian Høy, Ebbe S Hansen, and Cody Bünger Spine Unit, Department of Orthopaedics E, Aarhus University Hospital, Aarhus, Denmark Correspondence TA: tba@dadlnet.dk Submitted 08-11-17. Accepted 09-04-20 Background and purpose An increasing number of lumbar fusions are performed using allograft to avoid donor-site pain. In elderly patients, fusion potential is reduced and the patient may need supplementary stability to achieve a solid fusion if allograft is used. We investigated the effect of instrumentation in lumbar spinal fusion performed with fresh frozen allograft in elderly patients. Methods 94 patients, mean age 70 (60–88) years, who underwent posterolateral spinal fusion either non-instrumented (51 patients) or instrumented (43 patients) were followed for 2–7 years. Func- tional outcome was assessed with the Dallas pain questionnaire (DPQ), the low back pain rating scale pain index (LBPRS), and SF-36. Fusion was assessed using plain radiographs. Results Instrumented patients had statistically significantly better outcome scores in 6 of 7 parameters. Fusion rate was higher in the instrumented group (81% vs. 68%, p = 0.1). Solid fusion was associated with a better functional outcome at follow-up (sig- nificant in 2 of 7 parameters). 15 patients (6 in the non-instru- mented group and 9 in the instrumented group) had repeated lumbar surgery after their initial fusion procedure. Functional outcome was poorer in the group with additional spine surgeries (significant in 4 of 7 parameters). Interpretation Superior outcomes after lumbar spinal fusion in elderly patients can be achieved by use of instrumentation in selected patients. Outcome was better in patients in which a solid fusion was obtained. Instrumentation was associated with a larger number of additional surgeries, which resulted in a lesser degree of improvement. Instrumentation should not be discarded just because of the age of the patient.  Instrumented spinal fusion in elderly patients has been prob- lematized due to the risk of screw loosening and comorbidity (Hu 1997, Okuyama et al. 2001, Okuda et al. 2006, Cho et al. 2007), leaving uninstrumented fusion as an obvious alterna- tive. Spinal instrumentation has only been shown to increase fusion rates compared to uninstrumented fusion; the effect on functional outcome has been insignificant (Gibson and Wad- dell 2005). These studies have, however, all been performed using autograft as fusion material and also mostly in younger patients. The use of autograft has been problematized due to increased concern about the amount and extent of pain aris- ing from the donor site (Arrington et al. 1996, Robertson and Wray 2001, Sasso et al. 2005). In order to overcome the prob- lems of donor site pain, allograft and bone substitutes have gained increasing interest (Sandhu et al. 1999, Ehrler and Vaccaro 2000). Fresh frozen allograft has been one of the most widely used. One randomized study has shown that it gives similar outcomes compared to autograft in instrumented posterolateral fusion (Gibson et al. 2002); however, most sur- geons still believe that autograft has superior qualities (An et al. 1995, Sandhu et al. 1999, Ehrler and Vaccaro 2000). The use of allografts in the older patient population may be prob- lematic due to reduced fusion potential (Lohmann et al. 2001, Laursen et al. 2003). One long-term study in an elderly popu- lation has shown significantly better outcomes in patients in which a solid fusion was obtained compared to those without (Kornblum et al. 2004). Thus, the beneficial effect of instru- mentation in lumbar spinal fusion might be more pronounced in an older patient population fused with allograft. The aim of this study was to compare instrumented and non-instrumented lumbar spinal fusion performed using fresh frozen allograft in patients older than 60 years with regard to functional outcome and fusion rates. Open Access - This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the source is credited. DOI 10.3109/17453670903170505