Table 2.
Studies relating to the application of navigation technology in the thoracic spine
| Author (ref.) | Study design | Vertebral bodies | Pathology | Surgical approach | Image acquisition | Endpoint | n | Result/conclusion | |
|---|---|---|---|---|---|---|---|---|---|
| Patients | Screws | ||||||||
| Assaker et al. [7, 8] | Cadaver | n/a | n/a | Ventral | CT matching (paired point (fiducials) + surface | Accuracy | 1 | n/a | Registration error: 0.96 mm Navigation error: 1.6 mm |
| Mirza et al. [67] | Cadaver | Th1–Th10 | n/a | Dorsal | 2D Fluoroscopy vs. CT matching | Accuracy | 20 | 70/99/74 | Perfect screws: fluoro nav. (multi references) 60 (86%); fluoro nav. (single reference): 31 (31%); standard fluoroscopy: 70 (74%); CT based navigation: 51 (69%) |
| Hart et al. [35] | Cadaver | Th1–Th10 | n/a | Dorsal | CT matching (paired points + surface) | Accuracy | 8 | 128 | No significant differences in the overall exit rates. Significant difference in exit rates between the middle (47%), compared with the upper (9%) and lower (16%) thoracic regions, respectively (p < 0.001) |
| Sagi et al. [89] | Cadaver | Th1–Th12 | n/a | Dorsal | 2D Fluoroscopy | Accuracy | 4 | 48/48a | Misplacement rate nav. vs. convent. 8%/10%. Average degree of perforation was 1.7/2.4 mm (nav./convent., p = 0.055). X-ray time: per screw was 3.6/5.9 s/screw (nav./convent., p = 0.045). Insertion time per screw was 2.98/4.35 min/screw (p = 0007) |
| Kothe et al. [51] | Cadaver | Th2–Th8 | n/a | Dorsal (extrapedicular) | CT matching (paired points + surface) | Accuracy feasibility | 4 | 54 | Mean registration error ± SD: 1.0 ± 0.94 mm for the distance to the medial pedicle wall and 1.9 ± 1.44 mm for the distance to the anterior cortex. Angular measurements: 1.6° ± 1.1° for the transverse screw angle and 2.1° ± 1.6° for the sagittal screw orientation |
| Austin et al. [9] | Cadaver | Th6, 8, 10, 12 | n/a | Dorsal | CT matching (paired point) | Accuracy | 8 | ||
| Vaccaro et al. [103] | Cadaver | Th9–Th11 | n/a | Ventral open | 2D Fluoroscopy vs. conv. fluoroscopy vs. 3D fluoroscopy vs. FluoroNav EM | Accuracy | 4 | 16 | Standard fluoroscopy: tended to aim anterolaterally by 18°. Image-guidance systems: more accurate in the transverse plane compared with standard fluoroscopy. Significant difference in coronal plane screw angulation (angle of divergence with the superior endplate) between any of the imaging methods |
| Ohmori et al. [73] | Case report | Th12–L1 | Mixed | Ventral | CT matching (paired point) |
Feasibility | 3 | n/a | The tip of the standard probe and the angled rongeur could be monitored on 3D images during surgery, the retropulsed fragments within the spinal canal could be safely and completely removed under computer assistance |
| Seichi et al. [95, 96] | Case report | Th3–L2 | Ossification of the posterior longitudinal ligament | Ventral | CT matching | Feasibility | 3 | n/a | Mean registration error: 0.5–0.8 mm |
| Assaker et al. [7, 8] | Case report | Th8–Th9 | Calcified disc herniation | Ventral (thoracoscopic) | CT matching (paired point) | Feasibility | 1 | n/a | Navigation was reliable and a helpful monitoring device to achieve the surgical goals through endoscopic approaches |
| Kosmopoulos and Schizas [49] | Meta analysis | Th1–Th12 | Mixed | Dorsal | Mixed | Accuracy | 717/343a | Navigation provides a higher accuracy in the placement of pedicle screws for most subgroups analysed except for the thoracic levels (in vivo and cadaveric populations), where no advantage in the use of navigation was found | |
| Wendl et al. [108] | Prospective | Th1–Th12 | Mixed | Dorsal | 3D Fluoroscopy | Accuracy | 13 | 70 | Misplacement rate: 0.71%, lowest average fluoroscopy time (1.28 ± 0.56 min) with Iso-C3D navigation at a comparable average OR time (103.26 ± 23.3 min) |
| Schnake et al. [94] | Prospective | Th2–Th12 | Mixed | Dorsal | CT matching | Accuracy | 85 | 211/113a | Misplacement rate: navigated: 7.5% (1.9% of the navigated screws perforated the pedicle wall by more than 4 mm) conventional: 31.9% |
| Arand et al. [3, 4] | Prospective | Th3–Th12 | n/a | Dorsal | CT matching | Accuracy | 45 | Misplacement rate: navigated: 20% conventional: 21% | |
| Fritsch et al. [24] | Prospective | Th4–Th12 | Mixed | Dorsal | 2D Fluoroscopy | Accuracy | 20 | 54 | Misplacement rates: medial: 1.8%, lateral 7.4% |
| Ohnsorge et al. [74] | Prospective | Th7–Th12 | Vertebral compression fracture | Kyphoplasty | 2D Fluoroscopy | Accuracy | 6 | n/a | The navigated drilling differed from the ideal trajectory by 1° to max. 4°. Conventional C-arm control led to a divergence of 4° to 8°. Radiation exposure was reduced by 76%, the operating time decreased by 40% if computer assistance was used |
| Rajasekaran et al. [79, 80] | RCT | Th1–Th12 | Deformity | Dorsal | 3D Fluoroscopy | Accuracy | 17/16a | 242/236a | Misplacement rate: conventional: 23% [non-navigation group: 4.61 ± 1.05 min (range 1.8–6.5)] navigated: 2%e [navigated: 2.37 ± 0.72 min (range 1.16–4.5)] |
| Johnson et al. [45] | Retrospective | n/a | Thoracoscopic discectomy | Ventral thoracoscopic | CT matching (paired point) | Accuracy | 16 | n/a | Mean registration error (calculated): 1.7 mm (range 1.4–2.0) Mean navigation errors (intraoperative): 1.2 mm (range 0.8–1.3) |
| Nottmeier and Crosby [72] | Retrospective | Th1–S1 | Mixed | Dorsal | CT matching (paired points + surface) | Registration time | 23 segments | Average registration time for a single vertebral segment (paired points and surface matching technique) was 117 s (1 min 57 s). Average accuracy obtained was 0.9 mm. Inaccurate registration occurred in 3/23 (13%) of the segments requiring a second attempt at registration. In 3/23 (13%) of segments, adequate navigation accuracy was maintained on an adjacent vertebral segment. Though associated with a learning curve, image-guidance can be used effectively and efficiently in spinal surgery | |
| Lekovic et al. [54] | Retrospective | Th1–Th12 | Mixed | Dorsal | 3D Fluoroscopy vs. 2D Fluoroscopy | Accuracy | 37 | 94/183b | Rate of unintended perforations is depend on pedicle diameter (p < 0.0001). No statistical differences between 2D and 3D fluoro matching related to rate or grade of cortical perforations |
| Ebmeier et al. [22] | Retrospective | Th1–Th12 | Mixed | Dorsal | CT matching | Accuracy | 112 | 365 | Misplacement rate: 6.3% (11.5% with a minimal lateral perforation (<2 mm) of the pedicle wall) |
| Youkilis et al. [111] | Retrospective | Th1–Th12 | Mixed | Dorsal | CT matching (paired points ± surface) | Accuracy | 65 | 266 | Reviewed: 224 screws, 19 cortical violations (8.5%). 11(4.9%) Grade II (<2 mm), 8 (3.6%) Grade III (>2 mm). 5 screws (2.2%) were thought to exhibit unintentional, structurally significant violations. Significantly higher rate of cortical perforation in the midthoracic spine (T4–T8, 16.7%; T1–T4, 8.8%; and T9–T12, 5.6%) |
| Rampersaud et al. [82] | Retrospective | Th2–Th12 | Mixed | Dorsal | 2D Fluoroscopy | Accuracy | n/a | 79 | Misplacement rate: thoracic: 31.6% (72% of pedicle breaches were lateral) lumbar: 10.6% |
| Arand et al. [5] | Retrospective | Th2–Th12 | Tumor | Dorsal | CT matching (paired points ± surface) | Accuracy | 8 | 26 | Misplacement rate: 14% 3D vs. 2D |
The studies are stratified into the subgroups case report, cadaver experiments, prospective and retrospective studies. There is one randomized controlled trial (RCT) investigating the application of navigated approaches to the thoracic spine and one metaanalysis (a navigated vs. conventionalb 3D vs. 2D fluoroscopy)