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Case Studies

O-arm System Case Study

O-ARM COMPLETE MULTIDIMENSIONAL IMAGING SYSTEM L3-L4 DLIF with CD HORIZON SOLERA Cortical Bone Screws with O-arm and StealthStation Navigation

Hospital: Methodist Neurological Institute
Surgeons: Paul Holman, MD Andrew Livingston, MD Blake N. Staub, MD
Part of Medtronic Surgical Synergy™ Procedural Innovations.

Patient History:

Placement of reference frame and clamp

75-year-old female with Synovial Cyst at L3-L4 with superimposed stenosis and Left L4 radiculopathy Grade I Degenerative Spondylolisthesis at L3-L4, with Degenerative Disc Disease and Osteoporosis with extended treatment with alendronate.

The O-arm Imaging System in place for first scan

The patient presented with a chief complaint of lower back and bilateral leg pain, left worse than right. She first noted symptoms in August of 2012 (15 months prior to surgery) with a more recent exacerbation of pain over the past three months. The discomfort occurs in both buttocks traveling more distally in the left leg in the anterolateral thigh down the medial aspect of the shin. Her symptoms are relieved when lying down and worse with standing and prolonged walking. She takes 3 hydrocodone (5/500mg) daily to manage the pain. The patient does have osteoporosis but has been taking alendronate for five years. No additional neurological symptoms were noted.

Past Medical History:

O-arm image dataset post interbody / pre-fixation

Type 2 Diabetes
Hyperthyroidism
Hypertension Physical Exam

Physical Exam

Visual inspection of the patient revealed normal coronal and neutral sagittal balance. Motor examination revealed normal confrontational power in both extremities with weakness in the left iliopsoas 4+/5. Sensory examination was notable for decreased pinprick sensation in the right L4 dermatome. Reflex exam showed absent right patellar reflex with a normal patellar reflex on the left and symmetrically depressed reflexes in both ankles.

Preoperative Imaging

Imaging studies included an MRI of the lumbar spine and 36” full length AP and lateral scoliosis x-rays with flexion-extension and side bending views. The MRI revealed a large left-sided synovial cyst with significant bilateral lateral recess stenosis. The patient was also noted to have grade I degenerative spondylolisthesis accentuated on the weight-bearing x-rays in comparison to the MRI. Sagittal balance and pelvic tilt were within normal parameters.

Procedure

The patient was first placed in the right lateral decubitus position using a flat top Jackson table. An L3-4 direct lateral interbody fusion (DLIF) was performed from the left side using intermittent C-arm fluoroscopic imaging. A Medtronic Spine & Biologics A CLYDESDALE® Interbody (12 x 22 x 50mm) was placed to reconstruct the disc space.

The patient was then turned to the prone position on the Jackson Axis spinal table to prepare for posterior decompression and instrumentation. A small midline incision was made with subperiosteal dissection to expose the L3 and L4 laminae and L3-L4 facet joints with placement of the midline retractor. The open spinous process clamp with the patient reference frame was attached to the spinous process of L3 to allow for optimal camera positioning and line of site, at the head of the patient. To increase surgical efficiency, the scrub tech prepared all navigation equipment during the exposure by carefully registering and verifying all instruments prior to the navigated spin.

The O-arm® Imaging System was brought into the room to perform a standard 13-second, 360-degree spin of the lumbar spine to allow for spinal navigation. All OR staff including the surgeon, anesthesiologist, and scrub techs stood behind a lead shield during the spin so as to not break scrub and prepare to move immediately into the next phase of the operation. The patient was draped to maintain sterility during the spin. Once the O-arm exam had completely transferred to the StealthStation®, the O-arm Imaging System was then removed.

DrHolmanOarm

Dr. Holman used the Universal Drill Guide and a 3.2 mm power drill to create a cortical screw tract that was manually sounded with a ball-tipped probe. During drilling of the pilot hole, a forward projection is saved on the StealthStation in both the axial and sagittal “trajectory views” (refer to images above) to provide a precise roadmap for subsequent tapping and screw placement.

navlocktap

The tract is then stereotactically tapped with the NavLock® CD HORIZON® SOLERA® 4.5 tap with POWEREASE®. The measurement tool within in the software allows the surgeon to optimize the width and length of the screws to implant. This process was repeated for each of the 4 holes.

navlockscrews

NavLock® CD HORIZON® SOLERA® 4.75 Screwdriver was then used to place screws (CD HORIZON® SOLERA® 5.5 x 35mm in L3 and 5.5 x 40mm in L4.). This fixation technique was chosen by the surgeon to minimize soft tissue dissection and capitalize on the excellent fixation afforded by cortical screws in patients with potentially suboptimal bone density.

After all fixation and guidance was complete, the reference frame was removed and Dr. Holman proceeded to perform a complete L3 laminectomy with total left medial facetectomy, bilateral foraminotomies, as well as remove the synovial cyst. Once the decompression was complete, rods were set in position and provisionally tightened. The O-arm Imaging System was then brought back into the room to perform a second spin of the patient confirming accurate placement of all screws and hardware. The O-arm was removed from the room followed by compression and final torque of the setscrews. The incision was closed in standard fashion.

OarmXray1

OarmXray2

“The StealthStation and O-arm allowed me to place spinal instrumentation with a high degree of accuracy while optimizing the trajectory, screw length, and diameter to provide optimal biomechanics for this case.” - Dr. Holman

Postoperative course

The patient awoke from surgery with noticeable improvement in her radicular leg pain and was treated with narcotics and muscle relaxers for expected postoperative surgical pain. She was mobilized with physical therapy the morning after surgery and discharged on postoperative day three. A set of follow-up x-rays was completed at her three-week postoperative follow up showing stable spinal alignment (refer to postop lateral x-ray to the right). The patient was able to tolerate post-surgical back pain with one hydrocodone daily, a 60% reduction from preoperative requirements.

OarmXray3

 

“These tools provide value not only for complex cases, but even in routine cases to optimize workflow, improve accuracy. The O-arm used with Stealth navigation is particularly beneficial in MIS cases to minimize radiation to the surgeon and operative team and minimize the need for postoperative imaging.” - Dr. Holman