ROBOTIC-ASSISTED SPINE SURGERYROLAND S. KENT, MD

AXIS SPINE CENTER

DISCLOSURE STATEMENT

• I have no disclosures relevant to the current topic

• Neither me nor my immediate family members receive income or other

benefits from industry related to robotic-assisted spine surgery.

WHAT IS ROBOTIC ASSISTED SPINE SURGERY?

THE TRUTH:

WHY?

• It’s cool?

•Marketing?

• Because we can?

RADIOGRAPHIC ANATOMY:MIS VS. ROBOTICS

WHY?

Efficiency in the ORCost Efficiency

Time Efficiency

Accuracy

Reduced radiation exposure

Deformity

ROBOTIC NAVIGATION

Capture Patients Seeking Less Invasive Surgery

Reduce Radiation Exposure2

Surgeons, staff, and patients

Procedural Consistency

Automate trajectory alignment

Pre-Operative and Intra-Operative Planning

Patient Value = Efficacy * Less Invasiveness

Optimize surgical placement

2 -Helm, Patrick A. "Spinal Navigation and Imaging: History, Trends, and Future.” IEEE 34.8 (2015): 1738-1746.3 –Tian, Nai-Feng, et. al. "Minimally invasive versus open transforaminal lumbar interbody fusion: a meta-analysis based on the current evidence.” Euro Spine J 22 (2013): 1741-1749.4 – O’Toole, John. “Surgical Site Infection Rates after Minimally Invasive Spine Surgery.” J Neurosurg Spine 11 (2009): 471-476

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HOW DID WE GET HERE?

• 1st Generation

• 2nd Generation

April 19, 2017

COST/TIME EFFECTIVENESSA Cost-Effectiveness Analysis of the Integration of Robotic Spine Technology in Spine Surgery

• Objective: Investigate the cost-effectiveness of adding robotic technology in spine surgery to an active neurosurgical practice.

• Methods: The time of operative procedures, infection rates, revision rates, length of stay, and possible conversion of open to

minimally invasive spine surgery (MIS) secondary to robotic image guidance technology were calculated using a combination

of institution-specific and national data points. This cost matrix was subsequently applied to 1 year of elective clinical case

volume at an academic practice with regard to payor mix, procedural mix, and procedural revenue.

• Results: 1,985 elective cases were analyzed over a 1-year period; of these, 557 thoracolumbar cases (28%) were analyzed.

Fifty-eight (10.4%) were MIS fusions. • 41.4% patients had governmental insurance, while 58.6% had commercial insurance. The weighted average diagnosis-related group

reimbursement for thoracolumbar procedures for the hospital system was calculated to be $25,057 for Medicare and $42,096 for

commercial insurance.

• Time savings averaged 3.4 minutes per 1-level MIS procedure with robotic technology, resulting in annual savings of $5,713.

• Improved pedicle screw accuracy secondary to robotic technology would have resulted in 9.47 revisions being avoided, with cost savings

of $314,661. Under appropriate payor mix components, robotic technology would have converted 31 Medicare and 18 commercial

patients from open to MIS. This would have resulted in 140 fewer total hospital admission days ($251,860) and avoided 2.3 infections

($36,312).

• Robotic surgery resulted in immediate conservative savings estimate of $608,546 during a 1-year period at an academic center

performing 557 elective thoracolumbar instrumentation cases.

• Conclusion: Application of robotic spine surgery is cost-effective, resulting in lesser revision surgery, lower infection rates,

reduced length of stay, and shorter operative time.

• Richard Philip Menger, Amey R. Savardekar , Frank Farokhi , Anthony Sin Department of Neurosurgery, Louisiana State University Health

Sciences Center, Shreveport, LA, USA Shriners Hospital for Children, Shreveport, LA, USA

• Neurospine

ACCURACYAccuracy of robot-guided versus freehand fluoroscopy-assisted pedicle screw insertion in

thoracolumbar spinal surgery

• OBJECTIVE The quest to improve the safety and accuracy and decrease the invasiveness of pedicle screw placement in spine surgery has led to

a markedly increased interest in robotic technology. The SpineAssist from Mazor is one of the most widely distributed robotic systems. The aim of

this study was to compare the accuracy of robot-guided and conventional freehand fluoroscopy-guided pedicle screw placement in

thoracolumbar surgery.

• METHODS Retrospective series of 169 patients (83 women [49%])

• Robot-assisted cohort (98 patients, 439 screws), pedicle screws were inserted with robotic assistance.

• Freehand fluoroscopy-guided cohort (71 patients, 441 screws), screws were inserted using anatomical landmarks and lateral fluoroscopic guidance.

• The accuracy of screw placement was assessed based on the Gertzbein-Robbins scale by a neuroradiologist blinded to treatment group. The radiological slice

with the largest visible deviation from the pedicle was chosen for grading. A pedicle breach of 2 mm or less was deemed acceptable (Grades A and B) while

deviations greater than 2 mm (Grades C, D, and E) were classified as misplacements.

• RESULTS:

• Robot-assisted cohort, a perfect trajectory (Grade A) was observed for 366 screws (83.4%). The remaining screws were Grades B (n = 44 [10%]), C (n = 15

[3.4%]), D (n = 8 [1.8%]), and E (n = 6 [1.4%]).

• Fluoroscopy-guided group, a completely intrapedicular course graded as A was found in 76% (n = 335). The remaining screws were Grades B (n = 57 [12.9%]),

C (n = 29 [6.6%]), D (n = 12 [2.7%]), and E (n = 8 [1.8%]).

• The proportion of nonmisplaced screws (corresponding to Gertzbein-Robbins Grades A and B) was higher in the robot-assisted group (93.4%) than the freehand

fluoroscopy group (88.9%) (p = 0.005).

• CONCLUSIONS The authors’ retrospective case review found that robot-guided pedicle screw placement is a safe, useful, and potentially more

accurate alternative to the conventional freehand technique for the placement of thoracolumbar spinal instrumentation.

• Molliqaj, et. al. Department of Neurosurgery, Geneva University Hospitals, Department of Neurosurgery, Göttingen University Hospital, Georg-August-University Göttingen, Germany

• Journal of Neurosurgery

ACCURACY

• What of is the cost of this:

• To the hospital?

• To the physician?

• To the patient?

DEFORMITYHOW DO WE GET FROM HERE TO THERE?

DEFORMITYHOW DO WE GET FROM HERE TO THERE?

PREOP PLANNING

SPINAL BALANCE

ROLAND S. KENT, MD

JP

• 72 y/o active female

• Severe lumbar stenosis at L3-4 with

neurogenic claudication

• Radicular symptoms in an L4

nerve distribution (right>left)

• Polio in childhood

• Recently diagnosed with Parkinson’s disease,

but neurologist attributes sxs to stenosis

• Back Pain at lumbosacral junction

STANDING SCOLIOSIS

FILMS

COBB ANGLE: 43

DEGS

LUMBAR LORDOSIS:

2 DEGS

C7 PLUMB LINE:

5.5 CM TO THE RIGHT

SVA: 15.2 CM

PELVIC PARAMETERS

SACRAL SLOPE

PELVIC TILT

PELVIC INCIDENCE

• PI=SS+PT

• Lumbar Lordosis should be +/- 10 degs of pelvic

incidence to balance SVA

• Age adjustment

• What do we need to correct sagittal balance

• LL=2 degs

• PI=55 degs

• Need 53 degs +/- 10 degs

DOES CORRECTION OF PREOPERATIVE CORONAL IMBALANCE MAKE A DIFFERENCE IN OUTCOMES OF ADULT PATIENTS WITH DEFORMITY?• OBJECTIVE: Determine the significance of coronal balance on spinal deformity surgery outcomes.

• SUMMARY OF BACKGROUND DATA: Sagittal balance has been confirmed as an important radiographic parameter correlating with adult

deformity treatment outcomes. The significance of coronal balance on functional outcomes is less clear.

• METHODS: Eighty-five patients with more than 4 cm of coronal imbalance who underwent reconstructive spinal surgery were evaluated to

determine the significance of coronal balance on functional outcomes as measured with the Oswestry Disability Index (ODI) and Scoliosis

Research Society outcomes questionnaires. Sixty-two patients had combined coronal (>4 cm) and sagittal imbalance (>5 cm), while 23 patients

had coronal imbalance alone.

• RESULTS: Postoperatively, 85% of patients demonstrated improved coronal balance. The mean improvement in the coronal C7 plumb line was

26 mm for a mean correction of 42%. The mean preoperative sagittal C7 plumb line in patients with combined coronal and sagittal

imbalan`ce was 118 mm (range, 50-310 mm) and improved to a mean 49 mm. The mean preoperative and postoperative ODI scores were 42

(range, 0-90) and 27 (range, 0-78), for a mean improvement of 15 (36%) (P = 0.00001; 95% CI, 12-20). The mean Scoliosis Research

Society scores improved by 17 points (29%) (P = 0.00). Younger age (P = 0.008) and improvement in sagittal balance (P = 0.014) were

positive predictors for improved ODI scores. Improvement in sagittal balance (P = 0.010) was a positive predictor for improved Scoliosis

Research Society scores. In patients with combined coronal and sagittal imbalance, improvement in sagittal balance was the most significant

predictor for improved ODI scores (P = 0.009). In patients with preoperative coronal imbalance alone, improvement in coronal balance

trended toward, but was not a significant predictor for improved ODI (P = 0.092).

• CONCLUSION: Sagittal balance improvement is the strongest predictor of improved outcomes in patients with combined coronal and sagittal

imbalance. In patients with coronal imbalance alone, improvement in coronal balance was not a factor for predicting improved functional

outcomes.

• Daubs MD, Lenke LG, Bridwell KH, Kim YJ, Hung M, Cheh G, Koester LA. Spine (Phila Pa 1976). 2013 Mar 15;38(6):476-83.

THE IMPACT OF POSITIVE SAGITTAL BALANCE IN ADULT SPINAL DEFORMITY• STUDY DESIGN: This study is a retrospective review of 752 patients with adult spinal deformity enrolled in a multicenter prospective database in

2002 and 2003. Patients with positive sagittal balance (N = 352) were further evaluated regarding radiographic parameters and health status

measures, including the Scoliosis Research Society patient questionnaire, MOS short form-12, and Oswestry Disability Index.

• OBJECTIVES: To examine patients with adult deformity with positive sagittal balance to define parameters within that group that might differentially

predict clinical impact.

• SUMMARY OF BACKGROUND DATA: In a multicenter study of 298 adults with spinal deformity, positive sagittal balance was identified as the

radiographic parameter most highly correlated with adverse health status outcomes.

• METHODS: Radiographic evaluation was performed according to a standardized protocol for 36-inch standing radiographs. Magnitude

of positive sagittal balance and regional sagittal Cobb angle measures were recorded. Statistical correlation between radiographic parameters and

health status measures were performed. Potentially confounding variables were assessed.

• RESULTS: Positive sagittal balance was identified in 352 patients. The C7 plumb line deviation ranged from 1 to 271 mm. All measures of health

status showed significantly poorer scores as C7 plumb line deviation increased. Patients with relative kyphosis in the lumbar region had significantly

more disability than patients with normal or lordotic lumbar sagittal Cobb measures.

• CONCLUSIONS: This study shows that although even mildly positive sagittal balance is somewhat detrimental, severity of symptoms increases in a

linear fashion with progressive sagittal imbalance. The results also show that kyphosis is more favorable in the upper thoracic region but very poorly

tolerated in the lumbar spine.

• Glassman SD, Bridwell K, Dimar JR, Horton W, Berven S, Schwab F. Spine. 2005;30(18):2024-2029.

SURGICAL OPTIONS:

A. Limited posterior osteotomy—

segmental

• Ponte

• Smith-Peterson

B. 3 column osteotomy—focal

• Pedicle Subtraction

C. Vertebral resection with anterior

column reconstruction—focal

More Bony resection→Higher Blood Loss→Increased morbidity

ALTERNATIVE SURGICAL OPTIONS:

• ACR without vertebral resection—a segmental approach

• Anterior approach

• Lateral approach

• Posterior approach?

• Expandable cages

•NO bony resection→Less Blood Loss

SURGICAL PLAN FOR CASE PATIENT

Recreation of normal sagittal and coronal alignment

Decompression of L3-4 segment

2 stage surgical intervention

1.Anterior and lateral interbody fusion with lordotic cages

2.Posterior instrumentation and necessary osteotomies

• Open

• Percutaneous with mini-open

AFTER STAGE 1

AFTER PERCUTANEOUS STAGE 2

ALRIGHT, THAT CASE LOOKS CRAZY

• Do these principles apply to “normal” spine

surgery???

• New literature indicates that applying these

principles to short segment cases has relevance

and will help decrease the likelihood of future

segmental failure.

2017

TEMPEL, ET AL.

• We found that higher postoperative PI-LL mismatch predicted ALD requiring

surgery. A PI-LL mismatch of more than 11◦ (in our cohort of 159 patients) had

a positive predictive value of 75%, and a mismatch greater than 26◦ had a

100% positive predictive value for the development of ALD requiring surgical

correction.

LETS LOOK AT ANOTHER EXAMPLE: JD: 66 Y/O MALE

Immediate Postop → One month Postop → 6 months postop (now it’s a preop)→ Immediate postop

LL 30 degs, Segmental 0 degs LL 14 degs Segmental 38 degs kyphosis LL 38 degs

JD: 1 YEAR POSTOP: LL 38 DEGS

SO WHAT DOES IT MEAN TO ME?

• Are there non-operative implications?

• Let’s look at another case:

TK

• 90 y/o otherwise healthy male

• CC: pain at lumbosacral and thoracolumbar

junction

• Rxs: allopurinol, amoxicillin, vit B-12, levothyroxine,

lisinopril, losartan, Pradaxa, pravastatin,

triamterene-HCTZ

• PSH: CABG with subsequent revision, bilateral TKA

• Remains very active and exercises daily

• Physical Examination:

• No Neurological deficit

• Able to lie on the floor in the supine position with

eventual relaxation and reduction of kyphosis

STANDING SCOLIOSIS FILMS

RADIOGRAPHIC MEASUREMENTS

• SVA: +10.3 cm

• LL: 6 degs

• PI: 57 degs

• PI-LL= 51 degs

TREATMENT?

• Surgery?

• Other Options?

• Is it possible to improve spinal alignment with non-surgical methods?

ALRIGHT, BACK TO THE ROBOT . . .IDEAL SCENARIO

Multi-Functional

Imaging Versatility

Unique Real-Time

Information

PITFALLS

• How does the robot work?

• Is it possible for the robot to be wrong

• How?

• Registration

• Technique

BASE STATION CAMERA STAND

Rigid Robot Arm

Active End Effector

Touchscreen

Monitor

NDI

Camera

x4

Stabilizers

PRIMARY SYSTEM

COMPONENTS

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OR SETUP

How Does the Robot Work?

Image Capture

• Intraoperative Fluoroscopy• Preoperative CT• Intraoperative CT

Multi-Functional

Unique Real-Time

Information

Imaging Versatility

Providing Real-Time “Information”

1. Active feedback on movement of anatomic reference (DRB)

• DRB disruption = biggest source of navigation failure

Multi-Functional

Imaging Versatility

Unique Real-Time

Information

Surveillance Marker

Dynamic Reference Array

How Does the Robot Work?

Providing Real-Time “Information”

2. Real-time visualization of instruments

Multi-Functional

Imaging Versatility

Unique Real-Time

Information

Passive markers

tracking instruments

How Does the Robot Work?

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Providing Real-Time “Information”

3. Deflection sensing technology for skive prevention

Multi-Functional

Imaging Versatility

Unique Real-Time

Information

Active force

monitoring

Active

movement

monitoring

How Does the Robot Work?

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MAINTAINING NAVIGATIONAL INTEGRITY1. Ensure the patient reference is secure

2. Monitor the patient reference for movement

3. Use good navigation technique

4. Ensure registration fixture is secure

5. Avoid skiving when making the entry hole

6. Use a rigid robotic arm to guide all instruments

7. Leverage Experience

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HOW DOES THE ROBOT WORK?

• Robotic + Navigation Guidance • Active & Adaptable End Effector• Integrated Instruments

Imaging Versatility

Unique Real-Time

Information

Multi-Functional

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FUTURE DIRECTIONS

• Other Applications

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