Study design: Systematic review of published incidence of radiographic adjacent segment degeneration (ASDeg) and symptomatic adjacent segment disease (ASDis) after arthrodesis or total disc replacement.
Objective: Assess impact of surgery method and other factors on the incidence of ASDeg and ASDis.
Summary of background data: Twenty-seven articles, none of which were class I or II, met the inclusion criteria. Twenty involved arthrodesis (1732 patients) and 7 involved arthroplasty (758 patients). Nineteen detailed ASDeg and 16 detailed ASDis.
Methods: Data were established for number of patients, gender, average patient age, incidence of ASDeg and ASDis, average time to follow-up, and level and type of surgery. Multivariate logistic regression was used to identify which parameters had a significant effect on the incidence of ASDeg and ASDis.
Results: Three hundred fourteen of 926 patients in the arthrodesis group (34%) and 31 out of 313 patients in the total disc replacement group (9%) developed ASDeg. (P < 0.0001) Multivariate logistic regression indicated that higher odds of ASDeg were associated with: older patients (P < 0.001); arthodesis (P = 0.0008); and longer follow-up (P = 0.0025). For ASDis, 173/1216 (14%) arthrodesis patients developed ASDis compared to 7/595 (1%) of arthroplasty patients (P < 0.0001). Using multivariate logistic regression, higher odds of ASDis were seen in studies with fusion (P < 0.0001), higher percentages of male patients (P = 0.0019), and shorter follow-up (P < 0.05).
Conclusion: Analysis of the literature suggests a correlation between fusion and the development of ASDeg compared to arthroplasty, but this association is dampened by the influence of patient age. There is a stronger correlation between fusion and ASDis compared to arthroplasty. The data supports only a class C recommendation (lowest tier) for the use of arthroplasty to reduce ASDis and disc degeneration compared to arthrodesis.