Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)



Committee Chair(s)

Kevin S. Masters


Kevin S. Masters


David Stein


Edward Heath


Richard Gordin


Rates of lumbar fusion surgery have been increasing with an estimated 192,000 procedures performed annually. However, satisfactory outcomes of lumbar fusion vary considerably and often emphasize technical success, such as arthrodesis, rather than Ill functional and quality of life outcomes. Interbody cage fusion was recently developed and touted as a superior alternative to existing lumbar fusion procedures. There is, however, a paucity of research to support these claims, particularly with regards to functional and quality of life outcomes. Moreover, predictive correlates of outcomes for interbody cage fusion have not been given adequate attention in the literature. The aims of this study were to characterize patients undergoing this new procedure, examine functional and multidimensional outcomes, and investigate the predictive efficacy of presurgical variables. A retrospective cohort research design was employed and entailed medical record reviews for presurgical data and telephone outcome surveys at least 18 months following surgery.

Seventy-three patients who had undergone lumbar interbody cage fusion were identified from the private practice of an orthopedic surgeon and the Workers' Compensation Fund of Utah. Presurgical variables coded for analysis included age at the time of surgery, severity rating of presurgical spinal pathology, smoking tobacco, depression, and pursuing litigation at the time of surgery. Of the total sample, 56 patients (76.7%) completed outcome surveys that assessed patient satisfaction, back-specific functioning, disability status, and physical and mental health functioning.

While arthrodesis was achieved for most patients (84%), almost half were dissatisfied with their current back condition. Outcomes regarding disability and functioning were mixed. Arthrodesis was only moderately associated with better outcome and for a quite limited set of measure s. Three of the five presurgical variables (tobacco use, depression, and litigation) were consistently predictive of patient outcomes.

Findings are discussed and compared to existing data on lumbar fusion procedures , and clinical implications for improved patient selection and possible interventions are highlighted. Consideration is given to the limitations of this study, such as retrospective design, no matched controls , and sample size. Directions for future research are suggested.



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