Minimally invasive atlantoaxial fusion.
ABSTRACT C1-C2 fusion has significantly advanced from predominantly wiring/cable modalities to more biomechanically stable screw-rod techniques. Minimally invasive surgical techniques represents the most recent modification of atlantoaxial fixation. The indications, rationale, and surgical technique of this novel procedure are described.
Six patients requiring C1-C2 fusion (5 type II odontoid fractures and 1 os odontoideum) underwent minimally invasive C1-C2 fusion over a 2-year period. The cohort consisted of 5 men and 1 woman with a mean age of 51 years (age range, 39-64 y). All 6 patients underwent bilateral segmental atlantoaxial fixation using an expandable tubular retractor.
The mean follow-up time was 32 months (age range, 24-46 mo) There were no intraoperative complications, and the mean estimated blood loss was 100 mL. Solid fusion was achieved in all 6 patients, without pathological motion on dynamic studies. Postoperative computed tomographic images showed no hardware malposition in the scanned patients (4 of the 6 patients).
Placement of C1 and C2 instrumentation using minimally invasive techniques is technically feasible. Because the instrumentation and the means of obtaining arthrodesis do not differ substantively from the standard approach, we would not anticipate long-term results to be different from those of an open procedure, apart from the approach-related morbidity.
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ABSTRACT: To describe the applied anatomy of a minimally invasive muscle-splitting approach used to reach the posterior aspect of the C1-C2 complex. Atlantoaxial fusion using a midline posterior approach and polyaxial screw and rod system is widely used. Although minimally invasive variations of this technique have been recently reported, the complex applied anatomy of these approaches has not been described. The C1-C2 complex represents an unique challenge because of its bony and vascular anatomy. In this study, the applied anatomy and feasibility of this technique are examined on cadavers. The microsurgical anatomy of the upper cervical spine is examined on a formalin-fixed and on a fresh cadaver. The muscle-splitting approach is performed on 12 fresh cadavers using this technique. The minimally invasive muscle-splitting approach is described in detail. Relevant anatomy and bony landmarks that aid screw placement in C1 and C2 could be well visualized. Using this approach, we were able to reach the lateral mass of the atlas and the inferior articular process and pars interarticularis of the axis in all of the nine cadavers. We placed mini polyaxial screws in C1 lateral mass and C2 pars interarticularis in four cadavers according to the technique described by Harms and Melcher. Using this approach, it was possible to reach the posterior aspect of C1 and C2; the relevant anatomy needed to perform a C1-C2 fusion could be well visualized.Anatomia Clinica 03/2014; 36(10). DOI:10.1007/s00276-014-1274-x · 1.33 Impact Factor
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ABSTRACT: To analyze qualitatively C2 nerve dysfunction after its transection in C1-2 posterolateral instrumented fusions. From 2002-2010, 20 consecutive patients underwent posterolateral instrumented fusions using C1 lateral mass and C2 pars or pedicle screws, mainly for type 2 dens fractures. Screws were placed under lateral fluoroscopic guidance using standard techniques. Bilateral C2 nerve roots were coagulated and transected in all patients. Mean follow-up was 30.7 months and consisted of clinical and radiographic examinations, telephone interviews, and mailed visual analogue scale (VAS) questionnaires assessing C2 nerve dysfunction. One patient was lost to follow-up after the initial postoperative visit. Fusion was evident in all patients with 12 months of follow-up and two of three patients with <12 months of follow-up. There were no instances of unintended neurologic deficits, vascular injury, cerebrospinal fluid (CSF) leak, or hardware malfunction or malposition. By the 2-week or 6-week office visit, 4 of 20 patients complained of sensory disturbance, and 2 had paresthesias in the C2 distribution. After longer follow-up, one additional patient developed mild sensory symptoms. Quality of life was adversely affected in only one patient. No patient developed neuropathic pain at any time after C2 sectioning. This study is the first series to describe C2 nerve function after posterior atlantoaxial instrumented fusion in adults of all ages. Sacrifice of the C2 nerve root increases fusion surface, allows for better preparation and decortication of the atlantoaxial joint, improves visualization for screw placement, and decreases blood loss and operative time without major clinical consequences.World Neurosurgery 11/2011; 78(1-2):170-7. DOI:10.1016/j.wneu.2011.07.010 · 2.42 Impact Factor
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ABSTRACT: Iliac crest autograft remains the gold standard for spinal fusion operations. Given risk of donor site morbidity, many centers utilize allograft. We reviewed published series of C1-2 posterolateral instrumented fusions with allograft and autograft. Online databases were searched for English-language articles reporting quantifiable outcome data published between 1994 and 2011 of posterior atlantoaxial instrumented arthrodesis with C1 and C2 screws. Thirteen studies describing 652 patients having autograft and seven studies describing 60 patients having allograft serve as the basis of this report. All studies were retrospective case series (Class III evidence). There were no differences in complications or mortality between the groups. There were trends toward shorter operative times and less blood loss using allograft. A higher proportion of patients in the allograft group underwent sacrifice of the C2 nerve root and decortication and packing of the C1-2 joints (P<0.0001). There was no significant difference in the proportion of surviving patients who achieved solid fusion in the autograft (642 of 644 [99.7%]) and allograft patients (59 of 59 [100%]; P = 1.0). This review is limited by the retrospective data and inconsistent methodology of fusion determination used in most studies. Modern instrumentation and proper surgical techniques result in high rates of successful C1-2 arthrodesis. The use of allograft is a treatment option (Class III evidence) during posterior C1-2 instrumentation and fusion operations. Randomized, controlled trials using standardized radiographic assessments are needed across spinal arthrodesis studies to better determine the prevalence of radiographic fusion and establish technique superiority.World Neurosurgery 12/2011; 78(3-4):326-38. DOI:10.1016/j.wneu.2011.12.083 · 2.42 Impact Factor