General Session: MIS-2
Presented by: R. Kube - View Audio/Video Presentation (Members Only)
R. Kube(1), D. Morrow(1)
(1) Prairie Spine & Pain Institute, Peoria, IL, United States
Background: MIS TLIF has been performed for some time. The less invasive nature of the procedure as compared to traditional open techniques has been theorized to provide benefit to the patient. We analyze whether there is any difference in functional outcomes including work capabilities at time of maximum medical improvement (MMI) between injured workers who have had Open versus MIS TLIF.
Methods: All 1 and 2 level TLIFs performed on injured workers by a single surgeon were reviewed. Patients were excluded if there were multiple injuries or previous surgeries. The cohort contained 24 Open cases and 17 MIS cases. One MIS case was lost to follow-up. All patients were followed at least through the time of MMI. VAS (back and leg), ODI, and work capability before surgery and at MMI were recorded. Final work capabilities were determined by an independent FCE in all cases not provided a full release. Full release was considered ability to work beyond 100lbs. Time to MMI was also measured. Results between Open and MIS cases were compared for significance.
Results: VAS for the back demonstrated an average improvement of 35.6(74.2 to 38.6, P< 0.0001) for MIS and 30.9(80.4 to 47.8, P< 0.0001) for Open. VAS for the legs showed an average improvement of 36.2(64.6 to 28.4, P< 0.0001) for MIS and 35.3(73.3 to 36.5, P< 0.0001) for Open. ODI had an average change of 26.9(58.4 to 31.5, P< 0.0001) for MIS and 15.7(57.3 to 40.8, P< 0.0001) for Open with MIS showing and advantage over Open (P=0.039). Time to MMI averaged 248.9 days for MIS and 306.3 days for Open. MIS showed an average increase in work ability from 12.5lbs. to 59.1lbs.(P< 0.0001) and Open showed an average improvement from 11.9lbs. to 42.5lbs.(P< 0.0001) with MIS showing an advantage over Open (P=0.034). 4/17 MIS and 1/24 Open returned to full duty (>100lbs) (P=0.053).
Conclusion: Both MIS and Open TLIF demonstrated a statistical improvement in VAS and ODI. Although there was a larger improvement in all parameters for the MIS group, statistical significance was not achieved for change in VAS but was seen for change in ODI (P=0.039). Though there was an average of 57 fewer days until MMI in the MIS group, there was no statistical difference. There was however a difference observed in the final work capabilities. MIS TLIF leads to a higher functional ability with the average worker able to lift 17 additional pounds at time of MMI. This carries important implications as the average MIS patient also fell into a higher US Dept. of Labor category, Medium Duty, while the Open group demonstrated a physical demand characteristic of Light Duty. Given the apparent improved functional outcome, we would recommend using MIS techniques whenever indicated as it can provide better opportunity for function and gainful employment for recovering workers. Given a P Value of 0.053, greater numbers of patients may also possibly lead to a statistical advantage for patients reaching full duty in the MIS population. Further research is necessary, but MIS TLIF appears to hold an advantage over Open TLIF in the Workers' Compensation population.