Motion-preserving treatment of unstable atlas fracture: transoral anterior C1-ring osteosynthesis using a laminoplasty plate

Abstract

Background: C1-ring osteosynthesis is a valid alternative to posterior C1-C2 or C0-C2 fusion to preserve important C1-C2 motion in the treatment of unstable atlas fractures. Nevertheless, the fixation instruments used in current studies for transoral anterior C1-ring osteosynthesis were not suitable for anterior anatomy of the atlas or did not have reduction mechanism. We therefore present this report to investigate preliminary clinical effects of transoral anterior C1-ring osteosynthesis using a laminoplasty plate in unstable atlas fractures.

Methods: From January 2014 to December 2017, 13 patients with unstable atlas fractures were retrospectively reviewed. All patients were treated with transoral anterior C1-ring osteosynthesis using a laminoplasty plate. Pre- and postoperative images were obtained to assess reduction of the fracture, internal fixation placement, and bone union. Neurological function, range of motion, and pain levels were evaluated clinically on follow-up.

Results: The surgeries were successfully performed in all cases. The average follow-up duration was 16.6 ± 4.4 months (range 12-24 months). One patient suffered screw loosening after operation and underwent replacement operation subsequently. Satisfactory clinical outcomes were achieved in all patients with ideal fracture reduction, reliable plate placement, well-preserved range of motion, and neck pain alleviation. All patients achieved bone union of fractures without loss of reduction or implant failure or C1-C2 instability during the follow-up. No vascular or neurological complication was noted during the operation and follow-up.

Conclusions: Transoral anterior C1-ring osteosynthesis using a laminoplasty plate is a effective surgical treatment for unstable atlas fractures. This technique has a ingenious reduction mechanism, and can provide satisfactory bone union and preservation of C1-C2 motion.

Keywords: Atlas fracture; C1-ring osteosynthesis; Internal fixation; Open reduction; Transoral approach; Unstable fracture.

Fig. 1

Posterior cervical laminoplasty screw-plate system. a Laminoplasty plate and tapping screws in different lengths. b Laminoplasty plates before and after shaping

Fig. 2

Reduction schematics. a The forceps handles were closed to impart a compression force to reset the fracture after placement of one side of plate and temporary reduction screw. b Reduction of fracture was achieved, and another side of plate was fixed using two screws. c The last screw was placed, and the temporary reduction screw was removed

Fig.3

A 32-year-old female with atlas fracture treated by transoral anterior C1-ring osteosynthesis using a laminoplasty plate. Preoperative cervical lateral (a) and open-mouth X-rays (b), axial CT (c, d) and MRI images (e) showed combined fracture of the anterior and posterior arches with type I TAL injury. Postoperative cervical lateral (f) and open-mouth X-rays (g) identified the relatively good C1–C2 alignment. Axial CT (h) and the reconstructed images (i) after surgery showed reduction of the anterior arch fracture and optimal plate location. Transoral intraoperative view (j) showed good position of anterior laminoplasty plate fixation. Cervical lateral (k) and open-mouth X-rays (l) at 6 months after surgery showed stable fixation. An axial CT image (m) at 6 months after surgery indicated solid bone union. The dynamic cervical X-rays (n, o) at final follow-up revealed no sign of instability of C1–C2 and no loosening of the fixation

Fig.4

A 41-year-old female with atlas fracture treated by transoral anterior C1-ring osteosynthesis using a laminoplasty plate. Preoperative open-mouth (a) and cervical lateral X-rays (b), and axial CT (c) showed combined fracture of the anterior and posterior arches. Postoperative open-mouth (d) and cervical lateral X-rays (e) revealed the relatively good C1–C2 alignment. Axial CT (f) after surgery identified good reduction of the anterior and posterior arch fractures, and optimal placement of plate. Open-mouth (g), cervical lateral (h) and dynamic X-rays (i, j) at 9 months after surgery showed reliable fixation without instability of C1–C2. Axial CT images (k, l) at 9 months after surgery indicated satisfactory bone union of anterior and posterior arch fractures