Fixation

Poor bone quality is an increasing challenge for surgeons [1], as older patients are increasingly meeting the indications for PCF surgery. Screw failure is a common issue (~5.2/patient) in PCF, and patients with poor bone quality are likely to be at greater risk [2,3]. 95% of surgeons have observed lateral-mass screw loosening or pull out [2,3]. The anatomically specific screws and thread forms found within the Symphony system allow for stronger fixation in poor quality bone, and may reduce revisions and complications associated with screw loosening or pull out.

Alignment

In terms of patient outcomes, improvements in regional cervical alignment following deformity correction correlate with an improvement in health-related quality of life (HRQoL) postoperatively [4]. There is a clear need for advanced instrumentation and stronger rods/materials to achieve the desired alignment in the surgical treatment of deformity [4]. Symphony offers stronger and stiffer constructs in the form of 3.5 and 4.0 mm cobalt-chromium rods that are biomechanically superior to titanium equivalents. Furthermore, Symphony offers a single system to cross the cervical-thoracic junction, thereby reducing the complexity of the surgical procedure. Within the Symphony system, screws are available in diameters from 3.5 mm to 5.5 mm, allowing for more stable fixation.

Surgical Revision

The number of posterior cervical revision surgeries undertaken globally is increasing (2%-27% at 41.3 months) [5]. Surgical revisions, specifically the extension of previous posterior cervical constructs, are challenging and can be very invasive for the patient [5]. Use of the Symphony Universal Connectors allows the size of the surgical incision to be significantly reduced. Furthermore, the Universal Connectors accept multiple sizes of rods (3.5 - 6.35 mm) and are able to connect to existing systems. This feature allows existing hardware to be extended rather than removed and replaced, thereby reducing surgical complexity and the duration of the revision procedure. The reduced operating room time offers both improved patient outcomes and economic savings for the hospital system.
Symphony offers a variable and comprehensive set of instrumentation and implants with a sterile packed option. This allows surgeons to handle cases of increasing complexity whilst simplifying instrumentation handling by OR staff and reducing reprocessing costs [6].

Radiographic evaluation

Her preoperative radiographic evaluation comprised x-rays, functional x-rays, computed tomographic, and magnetic resonance imaging scans (Fig 4) and demonstrated:

• A fusion of the motion segments C2/3/4 and C6/7
• A moderate implant loosening of the posterior C2 screw on the right side
• An afunctional disc prosthesis at the level C4/C5 with significant heterotopic ossifications (grade III) accompanied by a facet joint osteoarthritis in this motion segment
• A nonunion at the level C5/C6 with residual mobility in this motion segment
• A highly mobile degenerative spondylolisthesis at the level C7/Th1 with bilateral neuroforaminal stenosis

Preoperative imaging (Fig 4a-f), showing:

• C2-C4 posterior instrumentation and fusion.
• Anterior fusion after Anterior Cervical Decompression and Fusion (ACDF) C3/4 and C6/7.
• Status after total disc replacement of C4/5 with heterotopic ossifications.
• Nonunion C5/6 after ACDF C5/6.
• Spondylolisthesis C7/Th1 with neuroforaminal stenosis on both sides.
• A normal cervical angiogram (cave: artefacts).
  
  
  
  

Surgery

Based on the findings detailed above and the patient's excruciating pain, an anterioposterior revision surgery was performed in June 2020.

First, a C7/Th1 ACDF was performed via a left-sided approach. After decompression of the spinal canal and bilateral neuroforaminal decompression of the C8 nerve route, stabilization was achieved with a stand-alone Syncage-C (DPS) that already significantly reduced the spondylolisthesis.

Second, a posterior revision surgery was performed including implant removal of the posterior instrumentation between C2 and C4 followed by a laminectomy of C7 with bilateral foraminotomy of the C8 nerve routes. Re-instrumentation with isthmic screws at the level C2, lateral mass screws at the level C4, C5, and C6, as well as bilateral pedicle screws at the level T2 and T3 was performed using the new Symphony system (DPS). The Symphony system offered the opportunity to place 4.0 mm screws in the previous loosened screw location at the level C2. The 3.5 mm screws were placed in C4, C5, and C6, and 5.5 and 5.0 mm screws at T2 and T3, respectively. The 4.0 mm rod allowed a good direct connection between the cervical spine isthmic and lateral mass screws and the thoracic pedicle screws, providing adequate stability and allowing excellent reduction. An intraoperative image is shown in Fig 5. Postoperative x-ray evaluations are displayed in Fig 6ae.

Postoperative course

The patient improved significantly postoperatively with regard to her C8 radiculopathy, which had already disappeared the day after surgery. Her neck pain also improved significantly and on the day of discharge from the hospital (day 5 after surgery) she only needed analgesic medication (administration of 600 mg ibuprofen three times daily).
At 6-week postoperative follow-up, the patient was taking 600 mg ibuprofen once daily for a good night's sleep and she was satisfied with the postoperative course (VAS neck pain score: 2; arm pain score: 0). Hence, her rehabilitation program was started.

Postoperative imaging (Fig 6a-e), showing:

AC DF C7/Th1 (Syncage C) and posterior stabilization with Symphony of C2, C4, C5, C6, Th1, and Th2 using 3.5  (C4/5/6) 4.0 (C2), 5.0 (TH2) and 5.5 mm (Th1) screws and 4.0 rods.