Walking ability after primary vs. revision spinal fusion
The media, insurance carriers, government, and the public are increasingly interested the value of surgical treatments for spinal disorders. Since spinal arthrodesis is used to treat a variety of conditions and indications, value for spinal fusion is not easily comparable to treatments of a single joint surgery such as total hip arthroplasty.
To use walking ability (among other outcomes), an easily understood function common to all lower extremity surgery, to describe the impact of primary vs. revision fusion on long-term functional outcomes.
A review of prospectively collected clinical and radiographic data
551 consecutive adults undergoing instrumented fusion at one center
Visual analog pain score (VAS), Oswestry Disability Index (ODI), and pain medication records. Walk score (WS) from the ODI: 0-no limit. 1- walk one mile. 2- walk ½ mile. 3- walk ¼ mile. 4- cane or walker. 5- bedridden. (Walk scores are multiplied by 2 for analysis, same as ODI)
All patients underwent posterior spinal fusion with instrumentation (374 primary, 177 revision). Diagnoses: degenerative disease (365patients, average 3 levels) or deformity (186 patients, average 10 levels). Age averaged 61 years (19-90); 60 were smokers. Levels fused: 267 underwent 1-2 level fusion (207 primary, 60 revision), 102 underwent 3-4 level fusion (51 primary, 51revision), 182 underwent 5 or more levels (116 primary, 66revision). Clinical and radiograph outcomes assessed preop, 1year, 2 years, and latest follow up.
At 68 months follow up (25-188months), both primary and revision patients significantly improved all clinical outcome measures (p<0.01). Patients undergoing revision surgeries had similar ODI (p=0.875) but worse WS (p=0.001), at 2 years than primary fusion patients. Primary WS: preop-4.6, 1year- 2.2, 2 year- 2.6. Revision WS: preop-5.6, 1 year- 3.8, 2 year- 4.0. Primary VAS: preop-6.0, 1 year-2.6, 2 year- 3.0. Revision VAS: preop 6.7, 1 year- 4.0, 2 year- 4.1. Primary ODI: preop-45.2, 1 year-22.9, 2 year-26.2. Revision ODI: preop-56.2, 1 year-38.8, 2 year-38.0. Fusion length, gender, and age differences did not affect WS. Primary group complications: Nonunion-14(4%), adjacent fracture-6, infection-7, footdrop-5. Revision group complications: Nonunion-10 (17%), adjacent fracture-7, infection-3, footdrop-3.
Walk Scores broken out from the ODI provide a way to interpret an easily understood functional outcome after spine surgery that is useful apart from ODI. There was not a significant difference in the 2 year ODI between primary and revision fusion patients. Both primary and revision fusion more than doubled patients walking distance, and maintained that improvement long-term. Revision patients had significantly worse Walking Scores compared to primary fusion patients at 2 years.