Classifications of Spine Injuries

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
Introduction

• 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

Steep learning curve
Peng et al., Spine, 2009 Scheufler et al.,
Neurosurg, 2007 Schizas, Int Orthop, 2008
3
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 5179, 2001
4
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 gt minimum 1yr

5
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

6
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

7
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
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)
• plt0.05

9
Results

• Operative time (F/U gt 1yr n41)

Min

p0.000
Case
10
Results

• Operative time (Whole series 72 cases)

Min
Asymptote
Case
11
Results

• Operative time

Mean Op. Time
Case 1-20 249
Case 21-41 198

p0.000
12
Results
Mean Op. Time
Case 1-20 250
Case 21-41 198
Case 42-72 185

• Operative time

198
185

P lt 0.05

P gt 0.05

13
Results
Amount of Bleeding

• Intraoperative Bleeding

ml

p0.005
Case
14
Results
Amount of Bleeding

• Postoperative H-vac Drain

ml

p0.547
Case
15
Results
Amount of Bleeding

• Perioperative Blood Loss (Intraop Drain)

ml

p0.004
Case
16
Results

• Amount of Bleeding

p0.000


p0.190


17
Results

• Start of ambulation

PO Day
X 1
Ambulation
Case 1-20 2.80.6
Case 21-41 2.00.5
X 13
X 2
X 6
X 17
X 2

p0.000
Case 1-20
Case 21-41
18
Results

• Transfusion incidence

Yes No
Case 1-20 6 14
Case 21-41 0 21

p0.009
19
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
20
Results

• Oswestry Disability Index

ODI
PreOp. 24
Final 7
21
Results

• VAS for Low Back Pain

LBP
PreOp. 5.1
Final 1.7
22
Results

• VAS for Radiating Pain to Legs

RP
PreOp. 6.9
Final 0.8
23
Results

• Case 1-20 versus Case 21-41

Plt0.05
24
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
  surgeons experience.

Mean Op. time
Case 1-20 249 min
Case 21-41 198 min
25
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
26
Thank you very much.