Prevalence and Clinical Relevance of Sacroiliac Joint Pain Secondary to Lumbar Fusion Procedures

Abstract

IntroductionLumbar fusion procedures for the treatment of appropriately selected cases of degenerative lumbar spine disease are rapidly increasing, with reported good overall results. However, an estimated 5 to 30% of these patients may suffer from significant persisting low back pain, despite technically successful surgery. In this setting, sacroiliac joint (SIJ) dysfunction has been postulated as possible underdiagnosed cause for these persisting symptoms. We aimed to assess the prevalence, associated risk factors and clinical impact of SIJ pain after lumbar fusion procedures. Material and MethodsRetrospective observational study of consecutive patients undergoing lumbar fusion at a single center between September 2012 and January 2014. A transversal evaluation through telephone interview was conducted, investigating the presence and characteristics of residual low back pain. Numeric pain rating scale (NPRS) for low back pain and Oswestry Disability Index (ODI) were collected for each patient. General demographic and surgery related data, including gender, age, body mass index, smoking status, number of segments fused and levels of fusion (including or not S1 level) was also noted. Selected patients with residual pain suspected to be of SIJ origin underwent clinical evaluation with a battery of 6 widely accepted SIJ provocative tests (FABER, SIJ sulcus tenderness, Gaenslen's test, Yeoman's test, compression test and sacral thrust). Those with 3 or more positive tests were considered to suffer from SIJ originated pain (SIJ-pain group). Statistical analysis comparing this group with the non-SIJ pain group (patients presenting with residual pain without clinical evidence of SIJ origin) regarding the collected variables was performed using SPSS 19 software. ResultsFrom a total of 89 patients that underwent surgery in this period, 52 patients were available for interview (mean age 59 years, 36.5% male, 63.5% female). Eight patients (15.4%) were completely asymptomatic, whereas 44 patients (84.6%) reported some degree of residual pain (mean NPRS of 4.73, mean ODI of 29.81%), although most reported clinical improvement and pain decrease with surgery. It was possible to clinically evaluate a final sample of 32 patients with residual pain (mean follow-up of 22.7 months). In 15 cases (46.9%) there was evidence of SIJ originated pain, as indicated by positiveness to 3 or more SIJ provocative tests. Presence of SIJ-pain was significantly associated with higher ODI scores (Mann-Whitney U 58.5, p = 0.009), and also tended to associate with higher NPRS scores (Mann-Whitney U 80, p = 0.071). Predictors for SIJ-pain development after surgery were not found, as there were no associations between the presence of SIJ-pain and the initially retrieved demographic and surgery related data, such as age, gender, BMI, smoking status, fusion to the sacrum and number of fused segments. ConclusionIn the post-lumbar fusion patient population that remains symptomatic after surgery, SIJ dysfunction and pain may account for a large proportion of cases, as illustrated by the impressively high rate of residual low back pain compatible with SIJ-pain found in this study (46.9%). Moreover, it may significantly affect functional outcome and surgery success rates, as patients in the SIJ-pain group presented worse ODI and NPRS scores than those with non-SIJ residual pain.