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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. Introduction.
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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
Introduction • Minimally Invasive TLIF • Advantages • Decreased soft tissue injury • Unilateral exposure & lessmuscle dissection • Preservation of contralateral structure • Decreased operative bleeding • Disadvantages • Technically demanding • Increased operative time Steep learning curve Peng et al., Spine, 2009; Scheufler et al., Neurosurg, 2007; Schizas, Int Orthop, 2008
Introduction • ‘New’ vs. ‘Gold standard’ procedure • False negative result • Too early assessment • Indifferent result • Positive result When? New Old (Gold standard) Learning curve for MIS TLIF? Ramsay CR et al: Statistical assessment of the learning curves of health technologies. Health Technol Assess 5:1–79, 2001
Materials • 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 • 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 • 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 • Laminectomy • Unilateral: 37 cases • Bilateral: 4 cases • Contralateral decompression • 16 cases
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
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
Results • Operative time (F/U > 1yr; n=41) Min * p=0.000 Case #
Results • Operative time (Whole series; 72 cases) Min Asymptote Case #
Results • Operative time * * p=0.000
Results • Operative time * * 198 185 * P < 0.05 § P > 0.05 §
Results Amount of Bleeding • Intraoperative Bleeding ml * p=0.005 Case #
Results Amount of Bleeding • Postoperative H-vac Drain ml § p=0.547 Case #
Results Amount of Bleeding • Perioperative Blood Loss (Intraop + Drain) ml * p=0.004 Case #
Results * • Amount of Bleeding p=0.000 * § p=0.190 * §
Results • Start of ambulation PO Day X 1 X 2 X 13 X 17 X 6 X 2 * p=0.000 Case# 1-20 Case# 21-41
Results • Transfusion incidence * p=0.009
Results • Occurrence of Complications Yes • Case # • #10: Deep infection • #24: Bone graft frag. extrusion from the cage • #25: Screw malposition • #41: Minimal dural tear No
Results • Oswestry Disability Index
Results • VAS for Low Back Pain
Results • VAS for Radiating Pain to Legs
Results • Case #1-20 versus Case #21-41 * * * * P<0.05
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.
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.