Object 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. Methods 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. Results 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. Conclusions 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.

Spinal instrumentation has made significant advances in the last two decades, with transpedicular constructs now widely used in spinal fixation. Pedicle screw constructs are routinely used in thoracolumbar-instrumented fusions, and in recent years, the cervical spine as well. Three-column fixations with pedicle screws provide the most rigid form of posterior stabilization. Surgical landmarks and fluoroscopy have been used routinely for pedicle screw insertion, but a number of studies reveal inaccuracies in placement using these conventional techniques (ranging from 10% to 50%). The ability to combine 3D imaging with intraoperative navigation systems has improved the accuracy and safety of pedicle screw placement, especially in more complex spinal deformities. However, in the authors' experience with image guidance in more than 1500 cases, several potential pitfalls have been identified while using intraoperative spinal navigation that could lead to suboptimal results. This article summarizes the authors' experience with these various pitfalls using spinal navigation, and gives practical tips on their avoidance and management.

Object The goal of this study was to analyze the placement accuracy and complications of thoracolumbar pedicle screws (PSs) inserted using 3D image guidance in a large patient cohort. Methods The authors reviewed the charts of 220 consecutive patients undergoing posterior spinal fusion using 3D image guidance for instrumentation placement. A total of 1084 thoracolumbar PSs were placed using either the BrainLAB Vector Vision (BrainLAB, Inc.) or Medtronic StealthStation Treon (Medtronic, Inc.) image guidance systems. Postoperative CT scanning was performed in 184 patients, allowing for 951 screws to be graded by an independent radiologist for bone breach. All complications resulting from instrumentation placement were noted. Using the intraoperative planning function of the image-guided system, the largest diameter screw possible in each particular case was placed. The screw diameter of instrumentation placed into the L3–S1 levels was noted. Results No vascular or visceral complications occurred as a result of screw placement. Two nerve root injuries occurred in 1084 screws placed, resulting in a 0.2% per screw incidence and a 0.9% patient incidence of nerve root injury. Neither nerve root injury was associated with a motor deficit. The breach rate was 7.5%. Grade 1 and minor anterolateral “tip out” breaches accounted for 90% of the total breaches. Patients undergoing revision surgery accounted for 46% of the patients in this study. Accordingly, 154 screws placed through previous fusion mass could be evaluated using postoperative CT scanning. The breach rate in this specific cohort was 7.8%. A total of 765 PSs were placed into the L3–S1 levels in this study; 546 (71%) of these screws were ≥ 7.5 mm in diameter. No statistical difference in breach rate was noted in PSs placed through revision spinal levels versus nonrevision spinal levels (p = 0.499). Additionally, no increase in breach rate was noted with placement of 7.5-mm-diameter screws. Conclusions Three-dimensional image guidance is a useful adjunct to placement of spinal instrumentation. The complication rate in this study was low, and accurate placement of instrumentation was achieved despite the high percentage of revision surgery cases in our patient population. Additionally, because active fluoroscopy was not used for instrumentation placement, there was minimal to no radiation exposure to the surgeon or operating room staff.

Surgical management of RA remains a challenging field. There clearly has been a decrease in cases of mutilating RA involving the craniovertebral junction. Surgical techniques for managing these conditions have steadily improved.

The correction of cervical kyphotic sagittal plane deformity can be accomplished safely and effectively using a 360-degree approach. The incidence of major complications in this study was low. All patients could be corrected to a neutral or lordotic alignment. No loss of deformity correction was seen in any patient, and a 97.5% fusion rate was obtained.

Sacral insufficiency fracture is a painful injury, for which no effective treatment currently exists. The objective of this study was to report on the clinical outcomes and technical aspects of balloon kyphoplasty, which was used in three patients with this injury. Three elderly women with intractable pain from sacral insufficiency fractures were treated with polymethyl methacrylate (PMMA) injections into the sacrum by using a modified balloon kyphoplasty procedure. The visual analog scale pain score improved by four points in each case. Functional status was improved and analgesic medication requirements were decreased in all three patients. There were no complications associated with the procedure. Because of the unique anatomy of the sacrum, it was difficult to monitor instrument placement and PMMA injection by using conventional fluoroscopy. BrainLAB image guidance was used in one case, and was helpful in guiding instrument placement and assuring accurate PMMA deposition at the fracture site. Balloon kyphoplasty may be a treatment alternative in selected patients with sacral insufficiency fractures. BrainLAB image guidance may offer some advantages over conventional fluoroscopy with regard to the monitoring of instrument placement and PMMA injection.

Anterior plate and posterior screw-rod fixation alone improve stability in a two-level, three-column cervical injury model. Combined fixation further improves stability. There is little discernible difference in immediate postoperative stability between posterior rod constructs combining lateral mass and pedicle screws and those using only pedicle screws.

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