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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

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Page 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

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

Page 2: 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

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

Page 3: 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

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?

Page 4: 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

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

Page 5: 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

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

Page 6: 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

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

Page 7: 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

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

Page 8: 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

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

Page 9: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Operative time (F/U > 1yr; n=41)

Case #

Min

p=0.000*

Page 10: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Operative time (Whole series; 72 cases)

Case #

Min

Asymptote

Page 11: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Operative time

p=0.000

*

*

Mean Op. Time

Case #1-20 249

Case #21-41 198

Page 12: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Operative time

**

P < 0.05*

§

§ P > 0.05

198185

Mean Op.

Time

Case #1-20 250

Case #21-41 198

Case #42-72 185

Page 13: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Intraoperative Bleeding

ml

Case #

p=0.005*

Amount of Bleeding

Page 14: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Postoperative H-vac Drain

ml

Case #

p=0.547§

Amount of Bleeding

Page 15: 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

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

Page 16: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Amount of Bleeding

** p=0.190§

§

p=0.000*

Page 17: 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

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# 1-20 Case# 21-41

PO Day

Ambulation

Case #1-20 2.8±0.6

Case #21-41 2.0±0.5

Page 18: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Transfusion incidence

p=0.009*

Yes No

Case #1-20 6 14

Case #21-41 0 21

Page 19: 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

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

Page 20: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Oswestry Disability Index

ODI

PreOp. 24

Final 7

Page 21: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ VAS for Low Back Pain

LBP

PreOp. 5.1

Final 1.7

Page 22: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ VAS for Radiating Pain to Legs

RP

PreOp. 6.9

Final 0.8

Page 23: 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

Learning curve for MIS TLIF

SCH spine center

Oct 15, 2009

Results ¬ Case #1-20 versus Case #21-41

*

*

*P<0.05*

Page 24: 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

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 #1-20 249 min

Case #21-41 198 min

Page 25: 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

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.Bleeding Perioperative B

Case #1-20 506 ml 689 ml

Case #21-41 272 ml 382 ml

Page 26: 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

Thank you very much.