MAST/MISS TLIFeffect of Age, BMI & Comorbidity in 200 patients

Petrus Stone, Neurosurgeon, Private PracticeBloemfontein, South Africa

2013-04-06

Disclosures

MAST/MISS Teaching on behalf of Medtronic

Sponsored attendance/travel

Study at my own expense

No animals were harmed

Literature

OPEN surgery Age – more

complicated BMI – more

complicated Comorbidity - more

complicated MI/MAST

Age – some studies BMI – some studies Co-morbidity – no

comparisons

Family debate– MISS Pros & Cons

Advantages (theoretical) Cosmesis, Pain, Hospital Stay, Blood Loss, Infection

Disadvantages (theoretical) Fusion Rate, Steep Learning Curve, Irradiation exposure

Objective

To what degree does co-morbidity affect (short term) outcome

Use of Information Patient/procedure

selection Resource allocation

(length of stay, High Care nights, transfusion, Physicians)

Patients / Materials And Methods 200 consecutive degenerative TLIF

cases since 2009-08-31 Review case notes, hospital notes

(myself; senior nurse) Excluded 6 cases

1x conversion to open 1x aborted procedure (revision of

open TLIF; screw holes too big) 1x cancellation on table (medical

aid interference) 3 trauma thoraco-lumbar cases

Stat analysis by UFS statistician

Descriptive Stats – The Patients

Previous surgery Scar tissue: 23% Remove Ix: 3.5%

Age Frequency Percent CumulativeFrequency

CumulativePercent

<65 166 83.00 166 83.00

65-70 15 7.50 181 90.50

70-75 13 6.50 194 97.00

>75 6 3.00 200 100.00

BMI Frequency Percent CumulativeFrequency

CumulativePercent

<35 145 72.50 145 72.50

35-40 29 14.50 174 87.00

>40 26 13.00 200 100.00

ASA Frequency Percent CumulativeFrequency

CumulativePercent

1 53 26.50 53 26.50

2 88 44.00 141 70.50

3 59 29.50 200 100.00

Descriptive Stats – The Procedures Surgical Time

Median 3 hours (1h25-9h30) (case no 9; 3 levels)

Levels operated / Orange River TLIF Class 1: 56.5%

A: 39% B-F: 15%

2: 40% A: 24.5% B-F: 15.5%

3: 3.5% A: 2.5% B-F: 1.0%

Medtronic : n = 181 (90.5%) Navigation: n = 8 (4%) Radiation exposure: median 3.1

minutes

TLIF sub-classes to accommodate for extra work• a – no extra work• b – 30 minutes• c – 60 minutes• EtcExamples• Vertebroplasty; • adjacent level discectomy;• Same level wide decompression/lami;• Remove instrumentation

Descriptive Stats – Short term Outcome Duration follow up: 30-880

days Length of ICU/High Care

stay 0 nights: 14,5% 1 night: 75.5% 2 nights: 9.5%

Length of postoperative hospital stay Median 3.9 days (0.9 to

17.9) Need for transfusion

3.5%

Major• threatening to life or limb

function• Early revision surgeryModerate• prolonged hospital stay or

outpatient treatment requiredMinor• inconvenient

Significant ComplicationsModerate local complications %

durotomies 7.5%

superficial sepsis 1.0%

iatrogenic end plate damage --> extra screws 0.5%

partial L5 weakness 1 (0.5%) 0.5%

persisting dysesthetic leg pain 0.5%

plunge with PAK needle (uncomplicated) 0.5%

screw too deep, Hb drop 0.5%

  11.0%

Major local complications %decompression same stay 1.0%fusion extension same stay 0.5%severe L4 nerve root damage 0.5%  2.0%

Major systemic complications %Pulmonary embolism 1.5%Unexpected epileptic fit 0.5%tachy-arythmia -> cardioversion 0.5%  2.5%

Moderate systemic complications %

respiratory (chest infection, atelectasis, sleep apnoea) 4.5%

arrhythmia 0.5%

quadriceps hematoma 0.5%

  5.5%

Age effectWorse• Transfusion if >70:

15.8%• LOS if >70: 3.8 vs 3.9

vs 5.7 days• ICU stay (hours not

nights) if >65

Similar• Complications • Theater, Cutting,

Radiation time

Group name Age Group 2    Subgroup names <65 >65 Fisher’s Exact Test % % p-value Sig?Transfusion required 2.41 8.82 0.0969-Durotomy/CSF leak 6.63 11.76 0.2918-Local (major) 1.81 2.94 0.5284-Local (moderate) 9.64 17.65 0.2241-Local (minor) 0.60 0.00 1.0000-Local (All: M, M, M) 12.05 20.59 0.4077-Systemic (major) 2.41 2.94 1.0000-Systemic (moderate) 4.82 8.82 0.4028-Systemic (minor) 18.07 29.41 0.1577-Systemic (all) 25.30 41.17 0.1415-Local or Systemic (major) 4.22 5.88 0.6515-Local or Systemic (moderate) 14.46 26.47 0.1914-Local or Systemic (minor) 18.67 29.41 0.1577-Significant blood loss  

ICU nights

1 night: 75.9%; 2 nights: 6.63% 1 night: 75.76%; 2 

nights 24.24% 0.0005YesKruskal-Wallis Test Median Median p-value Sig?LOS postop (days) 3.80 4.90 0.0451YesTheater Time (hours) 4.10 4.30 0.4115-Cutting Time (hours) 3.00 3.10 0.5770-ICU stay (hours) 20.50 21.70 0.0020YesRadiation Exposure (mins) 3.10 3.10 0.6888-

BMI effect

Worse• ICU nights• Theater, Cutting, RE

time

Similar• Complications• Hospital LOS

Group name BMI BMI Group 3

Subgroup names <35 >35 <35 35-40 >40

Fisher’s Exact Test % % p-value % % % p-valueTransfusion required 3.45 3.64 1.0000 3.45 0.00 7.69 0.2114

Durotomy/CSF leak 8.28 5.45 0.7642 8.28 6.90 3.85 0.9088Local (major) 1.38 3.64 0.3038 1.38 6.90 0.00 0.1821Local (moderate) 12.41 7.27 0.4478 12.41 10.34 3.85 0.5757Local (minor) 0.00 1.82 0.2750 0.00 0.00 3.85 0.1300

Local (All: M, M, M) 13.79 12.73 0.1729 13.79 17.24 7.70 0.1149Systemic (major) 2.76 1.82 1.0000 2.76 0.00 3.85 0.6015Systemic (moderate) 4.83 7.27 0.4985 4.83 6.90 7.69 0.6770

Systemic (minor) 18.62 23.64 0.4338 18.62 24.14 23.08 0.6583

Systemic (all) 26.21 32.73 0.8746 26.21 31.04 34.62 0.9190Local or Systemic (major) 4.14 5.46 0.7084 4.14 6.90 3.85 0.8519Local or Systemic (moderate) 17.24 14.54 0.6623 17.24 17.24 11.54 0.9036

Local or Systemic (minor) 18.62 25.46 0.4338 18.62 24.14 26.93 0.6583ICU - zero nights 17.36 7.27

0.0381

17.36 13.79 0.00

0.0312ICU - one night 75.69 76.36 75.69 68.97 84.62

ICU - two night 6.94 16.36 6.94 17.24 15.38

ICU nights              

Kruskal-Wallis Test median median p-value p-valueLOS postop (days) 3.90 4.00 0.1588 3.90 3.90 4.40 0.3392Theater Time (hours) 4.00 4.70 0.0209 4.00 4.60 5.20 0.0245Cutting Time (hours) 2.80 3.50 0.0163 2.80 3.20 3.80 0.0216

ICU stay (hours) 21.00 22.00 0.1765 21.00 20.40 23.00 0.1687

Radiation Exposure (mins) 3.00 3.70 0.0153 3.00 3.00 5.30 0.0012

Comorbidity (ASA) effect

Summary

More likely• Minor & Moderate

systemic Cx• Theater & Cutting

time• ICU stay? (integar

nights; not hours)

Similar occurrence• Local Cx• Major Systemic Cx• Transfusion• ICU nights (hours

not nights)• LOS

Group name ASA score ASA_Ex_BMI

Subgroup names ASA 1 ASA 2 ASA 3 ASA 1 ASA 2 ASA 3

Fisher’s Exact Test % % % p-value % % % p-value

Transfusion required 1.89 4.55 3.39 0.8867 1.59 4.69 0.00 0.5883

Durotomy/CSF leak 9.43 7.95 5.08 0.6999 7.94 7.81 0.00 1.0000

Local (major) 0.00 2.27 3.39 0.5810 0.00 3.13 0.00 0.4221

Local (moderate) 15.09 11.36 6.78 0.3714 14.29 10.16 0.00 0.5071

Local (minor) 0.00 0.00 1.69 0.5600 0.00 0.78 0.00 1.0000

Local (All: M, M, M) 15.09 13.63 11.86 0.4548 14.29 14.07 0.00 0.6124

Systemic (major) 3.77 2.27 1.69 0.7278 3.17 2.34 0.00 0.7349

Systemic (moderate) 1.89 6.82 6.78 0.4513 1.59 6.25 22.22 0.0491

Systemic (minor) 13.21 21.59 23.73 0.3462 11.11 22.66 44.44 0.0255

Systemic (all) 18.87 30.68 32.20 0.6372 15.87 31.25 66.66 0.0358

Local or Systemic (major) 3.77 4.54 5.08 1.0000 3.17 5.47 0.00 0.8168

Local or Systemic (moderate) 16.98 18.18 13.56 0.6589 15.88 16.41 22.22 0.7344

Local or Systemic (minor) 13.21 21.59 25.42 0.3462 11.11 23.44 44.44 0.0255

ICU - zero nights 26.42 12.64 6.780.0115

26.98 9.45 0.000.0034ICU - one night 66.04 81.61 76.27 66.67 81.10 66.67

ICU - two night 7.55 5.75 16.95 6.35 9.45 33.33

Kruskal-Wallis Test median median median p-value p-value

LOS postop (days) 3.80 3.90 4.00 0.2550 3.60 4.00 4.00 0.0857

Theater Time (hours) 3.60 4.20 4.70 0.0063 3.50 4.50 4.10 0.0008

Cutting Time (hours) 2.60 2.90 3.50 0.0153 2.40 3.30 2.90 0.0045

ICU stay (hours) 20.20 21.10 22.00 0.1933 20.20 21.10 25.20 0.0362

Radiation Exposure (mins) 2.90 3.00 3.70 0.0509 2.90 3.30 2.90 0.1182

Summary Age

>70: longer LOS (4 vs 6 days) >70: transfusion more likely (15

vs 2%) >65: ICU stay (hours not nights) ISQ complications

BMI Longer procedure, theater time,

irradiation time More ICU nights ISQ complications & LOS

Comorbidity (ASA score) Longer procedure ISQ complications & LOS