Posterior Cervical Facet Cages DTRAX

20 Posterior Cervical Facet Cages DTRAX

Melissa Meyer, John B. Ferraro, and Rahul V. Shah

Summary

DTRAX posterior cervical facet cages provide a minimally invasive, tissue sparing approach to performing posterior cervical fusion (PCF) surgery without significantly disrupting cervical paraspinal musculature or significantly affecting the posterior tension band. Traditional open PCF surgery with lateral mass fixation has been wrought with postoperative complications, particularly in older patients with multiple comorbidities. One study analyzing 3,401 patients who underwent traditional open PCF surgery with lateral mass screw (LMS) fixation exhibited a 30-day readmission rate of 6.20%.1 Of these, 4.97% of the patients required a return to the operating room.¹ Postoperative infection was the most common complication in 17.06% patients.¹ DTRAX provides an alternative posterior approach for a select patient population. This innovative, tissue sparing, minimally invasive posterior cervical approach allows for faster recovery time, shorter hospital stay, and negligible blood loss.² Furthermore, a 2013 study by McCormack evaluating 60 patients who underwent DTRAX surgery illustrated zero vertebral artery injuries, nerve root injuries, spinal cord injuries, or reoperations.³ In addition, research has demonstrated that minimally invasive PCF with facet cages yields stability similar to traditional open PCF surgery with LMSs.⁴

Keywords: DTRAX facet cages posterior cervical fusion minimally invasive tissue sparing

20.1 Introduction

DTRAX posterior cervical facet cages provide a minimally invasive, tissue sparing approach to performing posterior cervical fusion (PCF) surgery without significantly disrupting cervical paraspinal musculature or significantly affecting the posterior tension band. Traditional open PCF surgery with lateral mass fixation has been wrought with postoperative complications, particularly in older patients with multiple comorbidities.¹ One study analyzing 3,401 patients that underwent traditional open PCF surgery with lateral mass screw (LMS) fixation exhibited a 30-day readmission rate of 6.20%.¹ Of these, 4.97% of the patients required a return to the operating room.¹ Postoperative infection was the most common complication in 17.06% patients.¹ DTRAX provides an alternative posterior approach for a select patient population. This innovative, tissue sparing, minimally invasive posterior cervical approach allows for faster recovery time, shorter hospital stay, and negligible blood loss.² Furthermore, a 2013 study by McCormack evaluating 60 patients who underwent DTRAX surgery illustrated zero vertebral artery injuries, nerve root injuries, spinal cord injuries, or reoperations.³ In addition, research has demonstrated that minimally invasive PCF with facet cages yields similar stability to traditional open PCF surgery with LMSs.⁴

20.2 Indications

•Indicated for C3–C7 levels.

•Foraminal stenosis with radiculopathy that has improved temporarily with injections.

•Facet-mediated pain not responsive to nonoperative measures.

•Pseudoarthrosis.

•Adjunct to multilevel anterior decompression and fusion.

•Adjacent level compromise following prior anterior cervical discectomy and fusion (ACDF).

20.3 Contraindications

•Facet joint tumors or trauma destroying facet joint.

•Active infection.

•Spondylolisthesis greater than grade 1 signifying flexion/extension instability.

20.4 Preoperative Planning

•Utilize neuromonitoring to monitor somatosensory evoked potential, maximum expiratory pressure as indicated.

•Anteroposterior (AP)/lateral cervical radiographs with flexion and extension views to rule out underlying instability.

•Computed tomography (CT) scan to identify extent of facet hypertrophy, facet autofusion, and posterior facet osteophyte complexes.

•CT scan/magnetic resonance imaging will help to determine severity of the foraminal stenosis. These findings will allow the surgeon to determine if it may be more appropriate to perform the DTRAX portion of a staged anterior and posterior fusion first.

20.5 Patient Positioning

•A Skytron/Maquet table typically works best and allows for best flouro access.

•Two blanket rolls or gel rolls are placed under the patient’s chest and pelvis.

•Cervical visualization harness is placed on the table prior to positioning the patient. The harness will help to optimize fluoroscopic visualization of the lower cervical levels in larger patients and patients with broad shoulders.

•A tuck sheet is placed at the middle of the table so that the patient’s arms may be adequately secured by the patient’s side.

•Wrist restraints are placed at the foot of the table. These will be used to gently traction the patient’s arms and further pull the shoulders out of the field of view (Fig. 20.1).

•The patient is placed in the prone position with a foam face pillow.

•The patient’s head is gently taped to the bed to minimize intraoperative rotation.

•The wrist restraints are secured and tractioned. The arms are tucked at the patient’s side. The shoulder harness is tractioned and secured at the foot of the bed.

•The knees should be bent with legs flexed. Note that this maneuver will loosen the wrist restraint traction. You must again increase the traction on the wrist restraints once the legs have been flexed. Intraoperatively you may now use the bed control to further extend the knees and traction shoulders out of the field of view.

•The patient is placed in slight reverse Trendelenburg to accentuate the point of cervical flexion and allow for better access.

•At this point, the two C-arms are brought into position. One is placed at the head of the table for AP view and the other comes in laterally (Fig. 20.2).

•Once the C-arms are in position, take initial lateral C-arm shots to assess for adequate visualization of the appropriate levels.

Fig. 20.1 Intraoperative table setup for patient position demonstrating chest and pelvis rolls, foam pads for the knees, and wrist restraints attached distally to allow for traction.

Fig. 20.2 Fluoroscopy C-arm positioning (a, b) in orthogonal orientation. (c) C-arm position to obtain the on-fos view.

20.6 Surgical Technique

•Obtain clear imaging.

•Identify and optimize the lateral view first (Fig. 20.3a):

○Utilize the table tilt in order to superimpose the facet joints.

○If necessary, wag the C-arm in order to better visualize the facet clear space.

•Identify and optimize the AP view (Fig. 20.3b):

○If the lateral view is precise, then the AP view should be crisp and well aligned at 90 degrees.

○If there is a need to tilt the C-arm on the AP view, then this implies either a cervical scoliotic deformity or a suboptimal lateral view.

•Identify and optimize the on-fos view (Fig. 20.3c):

○This view is obtained by orienting the C-arm for the AP view in line with the angle and orientation of the facet joints. This is approximately 64 ± 6 degrees off the axial plane⁵ (Fig. 20.2c).

○The on-fos view is considered to be the most reliable radiographic view utilized in this case.

○It is easy to get thrown off with straight AP and lateral views. Always confirm the location of the instrumentation by assessing the on-fos view.

•Once clear imaging has been obtained, mark out the landmarks for the medial and lateral aspect of the facet using fluoro and a marking stick.

•Next the patient is prepped and draped in routine fashion. Be sure to prep and drape out the patients lumbosacral region as well if electing to obtain autograft from the patient’s iliac crest. Local anesthetic is injected (Video 20.1).