Spinal fusion and diabetes: long-term outcomes and complications from a large series

2012

Background

Diabetes has been shown to increase the risk of post-operative wound infection in orthopedic procedures, with a few studies describing the risk for infection in spinal surgery. However, the full impact of DM on clinical outcomes and complications after spine fusion has not been studied. How DM compares to Non-DM patients for primary vs. revision surgery or the impact of fusion length also remain unknown.

Purpose

Define the risk of post-op complications and the long-term clinical outcomes of diabetic patients undergoing primary and revision spinal arthrodesis for degenerative disease, spondylolisthesis, and deformity.

Study Design

Retrospective review of prospectively collected outcomes

Patient Sample

380 consecutive adults who underwent posterior spinal fusion

Outcome measures

Visual analog pain scores (VAS), Oswestry disability index (ODI), pain medication records, and complications obtained preop, 1 year, 2 years, and latest follow up. Clinical and radiographic data was Infection rates were evaluated with Fisher's Exact test; VAS and ODI outcomes were evaluated by the Mann-Whitney test.

Methods

47 DM patients were compared to 333 Non-DM patients after posterior instrumented fusion for either deformity (129 patients, 12 with DM) or degenerative disease (251patients, 35 with DM); Fusion length: Deformity- 8 levels (4-15 levels), Degen-3 levels (1-3 levels). Excluded: tumor, level one trauma, nonfusion surgery. Prior surgery prior to the studied procedure- 256 patients (67%; 47 Deformity, 209 Degen). Average age- 63 years (19-90years).

Results Follow-up averaged 5years (24-188 months). DM patients had about twice the complications as non-DM patients. Infection: DM-3 (6.4%, 2 Degen, 1 Deformity), Non-DM- 11 (3.3%, 7 revision Deformity). Nonunions: DM-4 (8.5%, 3 Deformity), NonDM-15 (4.5%, 12 Deformity). Clinically, both groups improved, but DM patients improved less than non-DM at 2 years. VAS preop: DM-6.2, Non-DM-6.2; 2 years: DM-4.2 (p=0.0023), NonDM-3.45 (p=0.0005), p=0.1709 comparison. ODI preop: DM-52, Non-DM-49.4; 2years:DM-37(p<0.001), Non-DM-31.2(p<0.001), p=0.1794 comparison.

Conclusions

DM carries double the risk of infection and pseudoarthrosis in spinal fusions done for deformity or degenerative disease. DM patients undergoing revision surgery have the highest risk. While DM and Non-DM patients improved clinically, DM had more pain and lower function at 2 years than Non-DM patients. Power calculations were performed from this sample and indicate a further study with at least 240 patients in the diabetic arm and 1160 in the non-diabetic arm will be necessary to detect a statistically significant difference in outcomes.