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: 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
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ABSTRACT: OBJECTIVE: To review published series describing C1-2 posterolateral instrumentation, comparing outcomes in patients who had and did not have C2 nerve sacrifice. METHODS: Online databases were searched for English-language articles between 1994 and April 2011 pertaining to posterior atlantoaxial instrumentation with C1 lateral mass and C2 screws. Twenty studies describing 732 patients with C2 nerve preservation and 6 studies describing 361 patients with C2 sacrifice met inclusion criteria. RESULTS: All but one small study without a control group were retrospective case series, making all evidence class III. Excluding C2 nerve dysfunction, no neurological deterioration was observed. Three instances of vertebral artery injury were secondary to soft tissue dissection and one was secondary to C1 screw insertion. There were seven instances of C1 screw malposition in the preservation group and none in the section group. Reported in roughly 20% of patients, mean estimated blood loss tended to be lower with C2 nerve sectioning (213 vs. 471 mL) and operative times were somewhat shorter (118 vs. 132 minutes). C2 nerve section resulted in greater symptomatic numbness (11.6% vs. 1.3%; P < 0.0001) but less neuropathic pain (0.3% vs. 4.7%; P = 0.0002) compared with C2 preservation. CONCLUSIONS: Sacrifice of the C2 nerve root to aid in the insertion of C1 lateral mass screws when performing posterior atlantoaxial instrumented fusions is a treatment option (class III). It may decrease blood loss and operative duration, potentially advantageous in elderly or frail patients. Numbness occurred in roughly 12% of patients, an outcome that may be unacceptable to certain patient populations, but neuropathic pain was nearly absent in reported studies with nerve section. C2 nerve preservation and retraction for C1 screw placement may have higher incidence of neuropathic pain (∼5%). Rates of fusion are universally high independent of C2 nerve technique.World Neurosurgery 11/2011; 78(6). DOI:10.1016/j.wneu.2011.10.035 · 2.42 Impact Factor