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

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

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?

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

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

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

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

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

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

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

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

Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Operative time * * P < 0.05 * § § P > Mean Op. Time Case # Case # Case #

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

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

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

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

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# PO Day Ambulation Case # ±0.6 Case # ±0.5

Learning curve for MIS TLIF SCH spine center Oct 15, 2009 Results ¬Transfusion incidence p=0.009 * YesNo Case # Case #

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

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

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

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

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

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 cases. ¬Operative time was significantly decreased with a surgeon’s experience. Mean Op. time Case # min Case # min

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 # ml689 ml Case # ml382 ml

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