Stabilization of the atlantoaxial complex via C-1 lateral mass and C-2 pedicle screw fixation in a multicenter clinical experience in 102 patients: modification of the Harms and Goel techniques

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Stabilization of the atlantoaxial complex has proven to be very challenging. Because of the high mobility of the C1–2 motion segment, fusion rates at this level have been substantially lower than those at the subaxial spine. The set of potential surgical interventions is limited by the anatomy of this region. In 2001 Jürgen Harms described a novel technique for individual fixation of the C-1 lateral mass and the C-2 pedicle by using polyaxial screws and rods. This method has been shown to confer excellent stability in biomechanical studies. Cadaveric and radiographic analyses have indicated that it is safe with respect to osseous and vascular anatomy. Clinical outcome studies and fusion rates have been limited to small case series thus far. The authors reviewed the multicenter experience with 102 patients undergoing C1–2 fusion via the polyaxial screw/rod technique. They also describe a modification to the Harms technique.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>One hundred two patients (60 female and 42 male) with an average age of 62 years were included in this analysis. The average follow-up was 16.4 months. Indications for surgery were instability at the C1–2 level, and a chronic Type II odontoid fracture was the most frequent underlying cause. All patients had evidence of instability on flexion and extension studies. All underwent posterior C-1 lateral mass to C-2 pedicle or pars screw fixation, according to the method of Harms. Thirty-nine patients also underwent distraction and placement of an allograft spacer into the C1–2 joint, the authors' modification of the Harms technique. None of the patients had supplemental sublaminar wiring.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>All but 2 patients with at least a 12-month follow-up had radiographic evidence of fusion or lack of motion on flexion and extension films. All patients with an allograft spacer demonstrated bridging bone across the joint space on plain x-ray films and computed tomography. The C-2 root was sacrificed bilaterally in all patients. A postoperative wound infection developed in 4 patients and was treated conservatively with antibiotics and local wound care. One patient required surgical debridement of the wound. No patient suffered a neurological injury. Unfavorable anatomy precluded the use of C-2 pedicle screws in 23 patients, and thus, they underwent placement of pars screws instead.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Fusion of C1–2 according to the Harms technique is a safe and effective treatment modality. It is suitable for a wide variety of fracture patterns, congenital abnormalities, or other causes of atlantoaxial instability. Modification of the Harms technique with distraction and placement of an allograft spacer in the joint space may restore C1–2 height and enhance radiographic detection of fusion by demonstrating a graft–bone interface on plain x-ray films, which is easier to visualize than the C1–2 joint.</jats:p></jats:sec>

Complications and outcomes of posterior fusion in children with atlantoaxial instability

“…Although these techniques for upper cervical surgery have been extensively reported in adult series [27][28][29], there have been reports on its use in only a small series of pediatric populations. We performed the C1 lateral mass screw and C2 pedicle screw technique and C1-C2 transarticular screw technique for C1-C2 fusion in six patients and achieved successful outcomes in five of the six cases.…”

Biomechanical and Morphometric Evaluation of Occipital Condyle for Occipitocervical Segmental Fixation

“…The incidence of neuropathic pain from C2 root sacrifice is very low. 4,6) The C0-C1 transarticular screw and direct occipital condyle screw can only be used if the occipital condyle is intact. This fixation technique cannot be considered in the presence of occipital bone fractures that extend to the condyle, and we do not advocate this fixation technique for comminuted or displaced fractures of the occipital condyle.…”

Diagnosis of Atlantoaxial Instability Requires Clinical Suspicion to Drive the Radiological Investigation

“…Examination often demonstrates tenderness over C1-C2, altered mechanics of neck rotation, hyperreflexia, dysdiadochokinesia, hypoesthesia to pinprick. Weakness is not a constant feature of AAI [4,[23][24][25][26][27].…”

“…Failure of any of the components of the atlantoaxial ligament complex requires dorsal surgical fusion [35]. This is most often accomplished with posterior screw constructs, transarticular screw fixation [24], or C1-C2 lateral mass/pedicle screws and interposed graft [4,25,26] (Figure 5). Aberrant vertebral artery anatomy may preclude the desired screw placement in 18% to 23% of patients [36,37], and the surgery may be complicated in EDS by small bone architecture.…”