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Samuel W. Terman, Timothy J. Yee, Darryl Lau, Adam A. Khan, Frank La Marca and Paul Park


Minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) has been demonstrated in previous studies to offer improvement in pain and function comparable to those provided by the open surgical approach. However, comparative studies in the obese population are scarce, and it is possible that obese patients may respond differently to these two approaches. In this study, the authors compared the clinical benefit of open and MI TLIF in obese patients.


The authors conducted a retrospective cohort study based on review of electronic medical records at a single institution. Eligible patients had a body mass index (BMI) ≥ 30 kg/m2, were ≥ 18 years of age, underwent single-level TLIF between 2007 and 2011, and outcome was assessed at a minimum 6 months postoperatively. The authors categorized patients according to surgical approach (open vs MI TLIF). Outcome measures included postoperative improvement in visual analog scale (VAS), Oswestry Disability Index (ODI), estimated blood loss (EBL), and hospital length of stay (LOS).


A total 74 patients (21 open and 53 MI TLIF) were studied. Groups had similar baseline characteristics. The median BMI was 34.4 kg/m2 (interquartile range 31.6–37.5 kg/m2). The mean follow-up time was 30 months (range 6.5–77 months). The mean improvement in VAS score was 2.8 (95% CI 1.9–3.8) for the open group (n = 21) and 2.4 (95% CI 1.8–3.1) for the MI group (n = 53), which did not significantly differ (unadjusted, p = 0.49; adjusted, p = 0.51). The mean improvement in ODI scores was 13 (95% CI 3–23) for the open group (n = 14) and 15 (95% CI 8–22) for the MI group (n = 45), with no significant difference according to approach (unadjusted, p = 0.82; adjusted, p = 0.68). After stratifying by BMI (< 35 kg/m2 and ≥ 35 kg/m2), there was still no difference in either VAS or ODI improvement between the approaches (both unadjusted and adjusted, p > 0.05). Complications and EBL were greater for the open group than for the MI group (p < 0.05).


Obese patients experienced clinically and statistically significant improvement in both pain and function after undergoing either open or MI TLIF. Patients achieved similar clinical benefit whether they underwent an open or MI approach. However, patients in the MI group experienced significantly decreased operative blood loss and complications than their counterparts in the open group.

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Timothy J. Yee, Brandon W. Smith, Jacob R. Joseph, Yamaan S. Saadeh, Jay K. Nathan, Elyne N. Kahn, Siri S. Khalsa, Kelsey J. Fearer, Michael J. Kirsch, David R. Nerenz, Victor Chang, Jason M. Schwalb, Muwaffak M. Abdulhak and Paul Park


The Oswestry Disability Index (ODI) is one of the most commonly used patient-reported outcome instruments, but completion of this 10-question survey can be cumbersome. Tools from the Patient-Reported Outcomes Measurement Information System (PROMIS) are an alternative, and potentially more efficient, means of assessing physical, mental, and social outcomes in spine surgery. Authors of this retrospective study assessed whether scores on the 4-item surveys of function and pain from the PROMIS initiative correlate with those on the ODI in lumbar spine surgery.


Patients evaluated in the adult neurosurgery spine clinic at a single institution completed the ODI, PROMIS Short Form v2.0 Physical Function 4a (PROMIS PF), and PROMIS Short Form v1.0 Pain Interference 4a (PROMIS PI) at various time points in their care. Score data were retrospectively analyzed using linear regressions with calculation of the Pearson correlation coefficient.


Three hundred forty-three sets of surveys (ODI, PROMIS PF, and PROMIS PI) were obtained from patients across initial visits (n = 147), 3-month follow-ups (n = 107), 12-month follow-ups (n = 52), and 24-month follow-ups (n = 37). ODI scores strongly correlated with PROMIS PF t-scores at baseline (r = −0.72, p < 0.0001), 3 months (r = −0.79, p < 0.0001), 12 months (r = −0.85, p < 0.0001), and 24 months (r = −0.89, p < 0.0001). ODI scores also correlated strongly with PROMIS PI t-scores at baseline (r = 0.71, p < 0.0001), at 3 months (r = 0.82, p < 0.0001), at 12 months (r = 0.86, p < 0.0001), and at 24 months (r = 0.88, p < 0.0001). Changes in ODI scores moderately correlated with changes in PROMIS PF t-scores (r = −0.68, p = 0.0003) and changes in PROMIS PI t-scores (r = 0.57, p = 0.0047) at 3 months postoperatively.


A strong correlation was found between the ODI and the 4-item PROMIS PF/PI at isolated time points for patients undergoing lumbar spine surgery. Large cohort studies are needed to determine longitudinal accuracy and precision and to assess possible benefits of time savings and improved rates of survey completion.