1. Analysis of Learning Curve for Minimally Invasive Transforaminal Lumbar Interbody Fusion Byung-Joon Shin, Jae Chul Lee, Hae-Dong Chang, Su-Jin Yun, Yon-Il Kim Spine Center Department of Orthopaedic Surgery Soonchunhyang University Hospital Seoul, Korea

2. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 ¬Minimally Invasive TLIF Advantages –Decreased soft tissue injury Unilateral exposure & less muscle dissection Preservation of contralateral structure –Decreased operative bleeding Disadvantages –Technically demanding –Increased operative time Introduction Steep learning curve Peng et al., Spine, 2009; Scheufler et al., Neurosurg, 2007; Schizas, Int Orthop, 2008

3. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 ¬‘New’ vs. ‘Gold standard’ procedure A.False negative result –Too early assessment B.Indifferent result C.Positive result Introduction New Old (Gold standard) Ramsay CR et al: Statistical assessment of the learning curves of health technologies. Health Technol Assess 5:1–79, 2001 Learning curve for MIS TLIF? When?

4. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 ¬Prospective analysis of The first 41 cases of MIS TLIF procedure Degenerative lumbar disease treated by –Decompression thru tubular retractor –Obliquely inserted a PEEK cage –Percutaneous pedicle screw fixation and fusion F/U > minimum 1yr Materials

5. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 ¬Patients characteristics Average age: 57 yrs (36-76) Average F/U: 21 m Etiology –Spinal stenosis: 24 cases –Spondylolisthsis: 12 cases –HIVD: 3 cases –IDD: 1 case –Seg. Instability: 1 case Materials

6. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 ¬Procedure (41 patients) No. of operated levels –1 level TLIF:31 cases –1 level TLIF + 1 level decomp:8 cases –2 level TLIF:2 cases Materials Laminectomy –Unilateral:37 cases –Bilateral:4 cases Contralateral decompression –16 cases

7. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Methods ¬Assessing parameters of learning curve Length of operative time Amount of bleeding Intraoperative bleeding H-vac drain Total perioperative bleeding Starting day of ambulation Transfusion incidence Occurrence of complications ¬Clinical outcome Oswestry disability index Visual analogue scale –Low back pain –Radiating pain to legs Learning curve

8. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Statistical analysis ¬Regression analysis for learning curve Bivariate analysis Case # vs. parameters (operative time, bleeding) Logarithmic curve-fit ¬Former 20 vs. Latter 21 cases Student T-test Operative time, Blood loss, Start of ambulation Chi-square test Transfusion need, Occurrence of complications ¬SPSS (ver.13.0) p<0.05

9. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Operative time (F/U > 1yr; n=41) Case # Min p=0.000 *

10. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Operative time (Whole series; 72 cases) Case # Min Asymptote

11. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Operative time p=0.000 * * Mean Op. Time Case #1-20249 Case #21-41198

12. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Operative time * * P < 0.05 * § § P > 0.05 198 185 Mean Op. Time Case #1-20250 Case #21-41198 Case #42-72185

13. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Intraoperative Bleeding ml Case # p=0.005 * Amount of Bleeding

14. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Postoperative H-vac Drain ml Case # p=0.547 § Amount of Bleeding

15. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Perioperative Blood Loss (Intraop + Drain) ml Case # p=0.004 * Amount of Bleeding

16. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Amount of Bleeding * * p=0.190 § § p=0.000 *

17. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Start of ambulation p=0.000 * X 1 X 13 X 6 X 2 X 17 X 2 Case# 1-20Case# 21-41 PO Day Ambulation Case #1-202.8±0.6 Case #21-412.0±0.5

18. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Transfusion incidence p=0.009 * YesNo Case #1-20 614 Case #21-41 021

19. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Occurrence of Complications Case # #10: Deep infection #24: Bone graft frag. extrusion from the cage #25: Screw malposition #41: Minimal dural tear Yes No

20. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Oswestry Disability Index ODI PreOp.24 Final7

21. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬VAS for Low Back Pain LBP PreOp.5.1 Final1.7

22. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬VAS for Radiating Pain to Legs RP PreOp.6.9 Final0.8

23. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Case #1-20 versus Case #21-41 * * * P<0.05 *

24. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Summary and Conclusions ¬Learning curve for minimally invasive TLIF was steep, but acceptable. Asymptote of the curve was approximately 35-40 cases. ¬Operative time was significantly decreased with a surgeon’s experience. Mean Op. time Case #1-20249 min Case #21-41198 min

25. Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Summary and Conclusions ¬Amount of bleeding and needs for transfusion also significantly decreased with a learning curve. ¬Minimally invasive TLIF can be an effective method treating degenerative lumbar diseases, provided appropriate training is obtained. Intraop.BleedingPerioperative B Case #1-20506 ml689 ml Case #21-41272 ml382 ml

26. Thank you very much.