On last week’s Spine Blog, Dr. Schairer’s article on readmission rates following adult deformity surgery was highlighted.1 This article reported a 12.3% readmission rate within 90 days of the initial surgery, with infection being the leading cause of readmission in the first 30 days. In the same issue of Spine, Dr. Kelly and his colleagues from Washington University in St. Louis reported their series of revision adult spinal deformity cases from 1995-2008 (n=45) and focused the analysis on the 21% (n=94) of patients who underwent further revision surgery. Of the 94 patients undergoing further revision, 2 year follow-up data was available for 74 patients who provided the data for this study. Of these 74 patients who underwent further revision surgery, 27% underwent multiple further revisions. The most common cause for the index revision and subsequent revision surgeries was pseudarthrosis (41% of index revisions and 31% of subsequent revisions). Painful hardware removal (iliac screws in the vast majority) was the second most common cause of subsequent revision, occurring in 20% of those undergoing a subsequent revision. Adjacent segment disease was the cause of the subsequent revision in 19%, while infection was the diagnosis in 10% of those requiring a subsequent revision. Scoliosis research society (SRS) outcome scores were available for 50 of the 94 patients undergoing subsequent revision, and these demonstrated improvements of 0.8 on the pain and function scales, 1.2 on the satisfaction scale, and 0.3 on mental health. While these were all statistically significant, the minimal clinically important differences (MCID) have not been well-defined for this outcome measure, so it is unclear how meaningful the improvement was other than for satisfaction.
This article dovetails nicely with the article featured last week, and the authors should be applauded for publishing their results and including an honest discussion about the difficulties associated with revision adult spinal deformity surgery. While the re-operation rate of 21% is relatively high, many patients did likely experience a meaningful improvement in their pain, function, and quality of life. The mean improvements in pain and function hovered around the authors’ estimate of MCID for this scale, so the average patient likely experienced modest improvement. Reporting a better studied outcome measure like the Oswestry Disability Index or SF-36 would have provided some further context to understand the degree of clinical improvement. An important finding in this study was that pseudarthrosis was the most common cause for both the index revision (41%) and subsequent revisions (31%). This is a recurrent theme in the adult deformity literature, and it represents a challenging problem. This group recently reported that the use of relatively high dose BMP in patients undergoing long fusions decreased the pseudarthrosis rate from 28% of patients treated with iliac crest bone graft to 6% of those treated with BMP.2 While this finding suggests a possible solution to the high pseudarthrosis rates observed in adult spinal deformity patients, other recent literature has suggested a possible link between high dose BMP and cancer.3 Obviously, further study is going to be needed to determine the underlying risks and benefits of BMP in the adult deformity population. This continues to be a challenging population to treat, and patients need to undergo thorough pre-operative counseling so that they truly understand the likely risks and benefits of revision deformity surgery as they make the difficult decision about whether or not to undergo operative treatment.
Please read Dr. Kelly’s article in the September 1 issue. Let us know if this changes your approach to treating the adult deformity patient considering revision surgery by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor
1. Schairer WW, Carrer A, Deviren V, et al. Hospital Readmission After Spine Fusion for Adult Spinal Deformity. Spine 2013.
2. Kim HJ, Buchowski JM, Zebala LP, Dickson DD, Koester L, Bridwell KH. RhBMP-2 is superior to iliac crest bone graft for long fusions to the sacrum in adult spinal deformity: 4- to 14-year follow-up. Spine 2013;38:1209-15.
3. Carragee EJ, Chu G, Rohatgi R, et al. Cancer risk after use of recombinant bone morphogenetic protein-2 for spinal arthrodesis. The Journal of bone and joint surgery American volume 2013;95:1537-45.