Sixty-one patients treated with C1-2 transarticular screw fixation for spinal instability participated in a detailed clinical and radiological study to determine outcome and clarify potential hazards. The most common condition was rheumatoid arthritis (37 patients) followed by traumatic instability (15 patients). Twenty-one of these patients (one-third) underwent either surgical revision for a previously failed posterior fusion technique or a combined anteroposterior procedure. Eleven patients underwent transoral odontoidectomy and excision of the arch of C-1 prior to posterior surgery. No patient died, but there were five vertebral artery (VA) injuries and one temporary cranial nerve palsy. Screw malposition (14% of placements) was comparable to another large series reported by Grob, et al. There were five broken screws, and all were associated with incorrect placement. Anatomical measurements were made on 25 axis bones. In 20% the VA groove on one side was large enough to reduce the width of the C-2 pedicle, thus preventing the safe passage of a 3.5-mm diameter screw. In addition to the obvious dangers in patients with damaged or deficient atlantoaxial lateral mass, the following risk factors were identified in this series: 1) incomplete reduction prior to screw placement, accounting for two-thirds of screw complications and all five VA injuries; 2) previous transoral surgery with removal of the anterior tubercle or the arch of the atlas, thus obliterating an important fluoroscopic landmark; and 3) failure to appreciate the size of the VA in the axis pedicle and lateral mass. A low trajectory with screw placement below the atlas tubercle was found in patients with VA laceration. The technique that was associated with an 87% fusion rate requires detailed computerized tomography scanning prior to surgery, very careful attention to local anatomy, and nearly complete atlantoaxial reduction during surgery.

Clinical success for both studies exceeded the study acceptance criteria of 85%. At 1-year follow-up, the flexion-extension range of motion per level: Discectomy and implantation of the device alleviates neurologic symptoms and signs similar to anterior cervical discectomy and fusion. Radiographic evidence supports maintenance of motion. The procedure is safe and the patients recover quickly. At least 5 years of follow-up will be needed to assess the long-term functionality of the prosthesis and protective influence on adjacent levels.

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Normal canal dimensions can be reestablished with open-door laminoplasty. Achieving and maintaining an increased sagittal canal diameter is probably the most important change in anatomic parameters to facilitate neurologic recovery. The use of titanium miniplates to stabilize the posterior elements after laminoplasty is a simple, durable, and effective technique to maintain the increased sagittal diameter of the spinal canal.

Object The management of odontoid fractures remains controversial. Only direct anterior screw fixation provides immediate stabilization of the spine and may preserve normal C1–2 motion. To determine the indications, optimum timing, and results for direct anterior screw fixation of odontoid fractures, the authors reviewed the surgery-related outcome of patients who underwent this procedure at two institutions. Methods One hundred forty-seven consecutive patients (98 males and 49 females) who underwent direct anterior screw fixation for a recent fracture (< 6 months postinjury [129 patients]) or remote (≥ 18 months postinjury [18 patients]) Type II (138 cases) or III (nine cases) odontoid fractures at the University of Utah (94 patients) and National Institute of Traumatology in Budapest, Hungary (53 patients) between 1986 and 1998 are included in this study (mean follow-up period 18.2 months). Data obtained from clinical examination, review of hospital charts, operative findings, and imaging studies were used to analyze the surgery-related results in these patients. In patients with recent fractures there was an overall bone fusion rate of 88%. The rate of anatomical bone fusion of recent fractures was significantly (p ≤ 0.05) higher in fractures oriented in the horizontal and posterior oblique direction (as compared with anterior oblique), but this finding was independent (p ≥ 0.05) of age, sex, number of screws placed (one or two), and the degree or the direction of odontoid displacement. In patients with remote fractures there was a significantly lower rate of bone fusion (25%). Overall, complications related to hardware failure occurred in 14 patients (10%) and unrelated to hardware in three patients (2%). There was one death (1%) related to surgery. Conclusions Direct anterior screw fixation is an effective and safe method for treating recent odontoid fractures (< 6 months postinjury). It confers immediate stability, preserves C1–2 rotatory motion, and achieves a fusion rate that compares favorably with alternative treatment methods. In contradistinction, in patients with remote fractures (≥ 18 months postinjury) a significantly lower rate of fusion is found when using this technique, and these patients are believed to be poor candidates for this procedure.