Stabilization with the Dynamic Cervical Implant: a novel treatment approach following cervical discectomy and decompression

Abstract

<jats:sec> <jats:title>OBJECT</jats:title> <jats:p>Although cervical total disc replacement (TDR) has shown equivalence or superiority to anterior cervical discectomy and fusion (ACDF), potential problems include nonphysiological motion (hypermobility), accelerated degeneration of the facet joints, particulate wear, and compromise of the mechanical integrity of the endplate during device fixation. Dynamic cervical stabilization is a novel motion-preserving concept that facilitates controlled, limited flexion and extension, but prevents axial rotation and lateral bending, thereby reducing motion across the facet joints. Shock absorption of the Dynamic Cervical Implant (DCI) device is intended to protect adjacent levels from accelerated degeneration.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>The authors conducted a prospective evaluation of 53 consecutive patients who underwent DCI stabilization for the treatment of 1-level (n = 42), 2-level (n = 9), and 3-level (n = 2) cervical disc disease with radiculopathy or myelopathy. Forty-seven patients (89%) completed all clinical and radiographic outcomes at a minimum of 24 months. Clinical outcomes consisted of Neck Disability Index (NDI) and visual analog scale (VAS) scores, neurological function at baseline and at latest follow-up, as well as patient satisfaction. Flexion-extension radiography was evaluated for device motion, implant migration, subsidence, and heterotopic ossification. Cervical sagittal alignment (Cobb angle), functional spinal unit (FSU) angle, and range of motion (ROM) at index and adjacent levels were evaluated with WEB 1000 software.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>The NDI score, VAS neck and arm pain scores, and neurological deficits were significantly reduced at each postoperative time point compared with baseline (p &lt; 0.0001). At 24 months postoperatively, 91% of patients were very satisfied and 9% somewhat satisfied, while 89% would definitely and 11% would probably elect to have the same surgery again. In 47 patients with 58 operated levels, the radiographic assessment showed good motion (5°–12°) of the device in 57%, reduced motion (2°–5°) in 34.5%, and little motion (0–2°) in 8.5%. The Cobb and FSU angles improved, showing a clear tendency for lordosis with the DCI. Motion greater than 2° of the treated segment could be preserved in 91.5%, while 8.5% had a near segmental fusion. Mean ROM at index levels demonstrated satisfying motion preservation with DCI. Mean ROM at upper and lower adjacent levels showed maintenance of adjacent-level kinematics. Heterotopic ossification, including 20% minor and 15% major, had no direct impact on clinical results. There were 2 endplate subsidences detected with an increased segmental lordosis. One asymptomatic anterior device migration required reoperation. Three patients underwent a secondary surgery in another segment during follow-up, twice for a new disc herniation and once for an adjacent degeneration. There was no posterior migration and no device breakage.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>Preliminary results indicate that the DCI implanted using a proper surgical technique is safe and facilitates excellent clinical outcomes, maintains index-and adjacent-level ROM in the majority of cases, improves sagittal alignment, and may be suitable for patients with facet arthrosis who would otherwise not be candidates for cervical TDR. Shock absorption together with maintained motion in the DCI may protect adjacent levels from early degeneration in longer follow-up.</jats:p></jats:sec>

Resorbable plating system stabilizes tissue‐engineered intervertebral discs implanted ex vivo in canine cervical spines

“…Mackiewicz et al confirmed in a finite element study that introducing highly stiff stabilizing plates into cervical spine motion segments increases stress in the endplate of adjacent segments and that plates that allow greater range of motion show up to 30% reduction of adjacent plates resulting stress . Matge et al discussed clinical and radiological observations that suggest dynamic cervical implants as a promising alternative to total disc replacement, anterior cervical discectomy and spinal fusion, and they indicate that preserving motion segment biomechanics reduces stress on facet joints and development of adjacent segment disease. The advantage of our combined approach over existing interbody cage designs and dynamic cervical prosthetics remains in that our TE‐IVD has been shown to remodel over time and mature to restore mechanical function of spine segments to native conditions, when stably implanted and fully engrafted …”

“…[29][30][31][32] Mackiewicz et al confirmed in a finite element study that introducing highly stiff stabilizing plates into cervical spine motion segments increases stress in the endplate of adjacent segments and that plates that allow greater range of motion show up to 30% reduction of adjacent plates resulting stress. 33 Matge et al 34 discussed clinical and radiological observations that suggest dynamic cervical implants as a promising alternative to total disc replacement, anterior cervical discectomy and spinal fusion, and they indicate that preserving motion segment biomechanics reduces stress on facet Figure 3D), since the inclined shape of the endplate in the ventral side combined with the lack of anchoring for the implant resulted in a wedge-like extrusion. These observations were consistent with the mechanism of extrusion observed in the displaced implants of our in vivo canine study.…”

“…We adapted the cell preparation methods from previously established protocols. 8,9 Briefly, we harvested cervical IVDs from three skeletally mature canine spines (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36) Similarly, we based the TE-IVD fabrication process on established techniques. 9,15 First, we mixed encapsulated canine NP cells (25 × 10 6 cells/mL) in 3% wt./vol.…”

Radiologic and Clinical Evaluation 12 Months after Anterior Cervical Diskectomy and Dynamic Stabilization of the Segment with Dynamic Cervical Implant

“…In vitro biomechanical testing 23 showed that the DCI has an intermediate place biomechanically between fusion and TDR. Restricted axial rotation and lateral bending protect the facet joints from extensive stress.…”

Der zervikale Bandscheibenvorfall – Spontanverlauf, Therapieoptionen und klinische Ergebnisse

“…Auch ein dynamisches Implantat ist unter der Vorstellung der Reduktion der Re-Operationen wegen ASD entwickelt worden. Bislang liegen allerdings keine ausreichenden Daten vor, die die Überlegenheit dieses Implantats im Vergleich zur ACDF gezeigt haben [8].…”