Reduction and arthrodesis with sublaminar spiral silk in atlantoaxial joint instability

Abstract

Objective: The aim of this study was to evaluate the clinical and radiologic results of the use of thick spiral silk knotting instead of sublaminar wiring for C1-C2 arthrodesis in patients with atlantoaxial instability. Methods: We retrospectively evaluated 16 patients (10 females, 6 males; mean age: 43.4 years; mean follow-up: 34 months) with atlantoaxial instability who underwent C1-C2 fusion by reduction and sublaminar spiral silk knotting. All patients underwent open reduction, bounding both laminae with thick spiral silk instead of wiring and arthrodesis with autografting. Reduction rates, screw position and fusion rates were evaluated using computed tomography. Results: Preoperative mean atlantodental interval (ADI) was 8 (range: 6 to 11) mm and postoperative ADI was 2.1 (range: 0.5 to 2.5) mm. There was no dural or spinal cord injury. Complete reduction was observed in all cases. Fusion was unsuccessful in 1 case (6.25%). Postoperative mean flexion ADI was 10 mm and mean extension ADI was 1 mm. Graft separation between C1-C2 was observed in slice tomographic examination in one patient. Malposition was observed in 2 screws (4%). Conclusion: The sublaminar silk knotting technique appears to provide safe anatomical reduction. As this method is cheap and simple and does not require extra implantation, loosen, create neurologic compromise or cause radiologic crowding, it can be considered an alternative surgical technique to sublaminar wiring.