The Spine Journal 15 (2015) 1141–1145
Technical Report
A novel technique of two-hole guide tube for percutaneous anterior odontoid screw fixation Ai-Min Wu, MD, Xiang-Yang Wang, MD PhD*, Dong-Dong Xia, MD, Peng Luo, MD, Hua-Zi Xu, MD, Yong-Long Chi, MD The Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# XueYuan Western Rd, Wenzhou, Zhejiang, 325027, People’s Republic of China Received 14 January 2014; revised 12 November 2014; accepted 3 February 2015
Abstract
BACKGROUND CONTEXT: Surgical stabilization is recommended for odontoid fractures with mechanical instability. Compared with C1–C2 fusion, percutaneous anterior odontoid screw fixation has the advantages of preserving C1/C2 motion and being a minimally invasive procedure. However, determining the optimal screw trajectory is often difficult. When an initial suboptimal K-wire hole is drilled, it is especially difficult to drill a second optimal K-wire trajectory because the initial hole will be entered inadvertently. PURPOSE: To design a novel device, two-hole guide tube, to make drilling a second optimal Kwire trajectory easier, and thus, avoid unnecessary additional surgical time and reduce the likelihood of needing to change the procedure to traditional open surgery. STUDY DESIGN: A technical report. METHODS: Fifty-three patients with odontoid fractures were treated by percutaneous anterior odontoid screw fixation in our hospital, and the initial K-wire trajectories of 16 cases (12 men and 4 women) among the 53 patients were imperfect. The two-hole guide tube was applied for drilling the second trajectory in each of these 16 cases. RESULTS: No complications associated with this technique occurred. Satisfactory results and good screw placement was achieved in all patients. Radiographic fusion was confirmed for 15 of 16 patients. None of the patients experienced clinical symptoms or screw loosening or breakage in this study. CONCLUSIONS: Our novel device, two-hole guide tube, can be used to reduce the difficulty associated with redrilling an optimal K-wire trajectory if the initial trajectory is imperfect during percutaneous anterior odontoid screw fixation. Moreover, by referring to the initial misplaced K-wire, a more accurate trajectory for the second K-wire can be achieved. Ó 2015 Elsevier Inc. All rights reserved.
Keywords:
Odontoid fracture; Guide tube; K-wire; Trajectory; Percutaneous; Minimally invasive; Technique note
Introduction FDA device/drug status: Not applicable. Author disclosures: A-MW: Nothing to disclose. X-YW: Nothing to disclose. D-DX: Nothing to disclose. PL: Nothing to disclose. H-ZX: Nothing to disclose. Y-LC: Nothing to disclose. This work was supported by the National Natural Science Foundation of China and Zhejiang Province. The authors declare that they have no conflicts of interest. * Corresponding author. The Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, Wenzhou, Zhejiang, People’s Republic of China. Tel.: (86) 0577-88002814; fax: (86) 0577-88002823. E-mail address: [email protected] (X.-Y. Wang) http://dx.doi.org/10.1016/j.spinee.2015.02.013 1529-9430/Ó 2015 Elsevier Inc. All rights reserved.
Odontoid fracture is a common injury in the upper cervical spine. Type II fractures and shallow Type III odontoid fractures (according to the classification of Anderson and D’Alonzo [1]) are mechanically unstable and are associated with a high risk of nonunion or mortality [2–4]. Thus, surgical stabilization is recommended for these patients [5]. Anterior odontoid screw fixation was first reported in the early 1980s [6]. Compared with C1–C2 fusion, this approach offers the advantage of preserving C1/C2 motion [7]. Moreover, the anterior odontoid screw can be inserted
1142
A.-M. Wu et al. / The Spine Journal 15 (2015) 1141–1145
percutaneously [8,9], which allows this approach to be minimally invasive and associated with reduced blood loss, quicker recovery, and shorter hospital stay compared with the traditional open surgery [10]. However, the surgical procedure for percutaneous anterior odontoid screw fixation is not always successful, and in some cases, it is difficult to determine the ideal screw trajectory on both anteroposterior (AP) and lateral views with C-arm simultaneously. Especially, when an initial suboptimal K-wire trajectory is drilled, it is difficult to redrill another optimal K-wire trajectory because the initial hole will be entered inadvertently. If another optimal K-wire trajectory cannot be drilled, it is impossible to introduce the anterior odontoid screw percutaneously. For this reason, some surgeons give up on the percutaneous technique and perform the traditional open technique. To overcome the difficulty associated with drilling an optimal second hole, we designed a novel device, which we refer to as the ‘‘two-hole guide tube’’ (Fig. 1). An optimal K-wire trajectory is known to be necessary for achieving a perfect odontoid screw trajectory because the screw is introduced along the K-wire [9]. Therefore, the optimal K-wire trajectory is very important and directly influences the success of percutaneous anterior odontoid screw fixation. Here, we describe the results of 16 operations performed using the two-hole guide tube.
Methods and materials Patient population Between January 2009 and February 2011, 53 patients with odontoid fractures were treated by percutaneous anterior odontoid screw fixation in our hospital. In 16 of these patients (12 men and 4 women), the initial K-wire trajectories were imperfect and drilling of a second more optimal
K-wire trajectory was necessary. Fourteen cases were Type II odontoid fractures and two were shallow Type III fractures according to the classification system established by Anderson and D’Alonzo [1]. Patient’s age ranged from 29 to 64 years (mean, 39.4 years). We used our novel twohole guide tube in these 16 patients. Preoperative lateral and AP (open-mouth) views and computed tomography (CT) scans were obtained to evaluate the feasibility of surgery. Surgical technique The general procedure followed for percutaneous anterior odontoid screw fixation was the same as that previously described by Chi et al. [9]. Briefly, patients were placed supine on the operating table, and anatomic reduction was achieved using Gardner-Wells skull traction tongs. An initial 5- to 10-mm incision was made medial to the right sternocleidomastoid muscle at the level of C4–C5 disc space, and blunt dissection was performed to reach the anterior border of the spinal column using the finger or hemostat. A protective tube was inserted first and then the guide tube was inserted inside the protective tube. The tip of the guide tube was placed anteroinferior to C2. The K-wire was drilled into the odontoid process, and the angle and position of the K-wire were confirmed by intraoperative fluoroscopic AP and lateral views. If the K-wire trajectory was confirmed to be imperfect (Fig. 2), we did not remove this imperfect K-wire immediately. While the previous one-hole guide tube was being removed and the two-hole guide tube was being applied, the initial, imperfectly placed K-wire was passed through one-hole of the two-hole guide tube and another K-wire was inserted through the other hole of the two-hole guide tube. Then, we adjusted the second K-wire to an optimal angle and trajectory referring to the initial, imperfectly inserted K-wire (Fig. 2), the initial imperfect K-wire and guide tube were removed after the second optimal K-wire trajectory was drilled. A recess for the screw head was fashioned with a cannulated drill bit along the second K-wire, and finally, the odontoid screw was introduced along the second K-wire (Fig. 2). After both the second K-wire and the guide tube were removed, the wound was checked for hemostasis and suture closure. Patients were allowed ambulatory activities on postoperative Day 2 with a cervical collar that was removed at 12 weeks after surgery. Postoperative lateral and AP (openmouth) views and CT scans were obtained to evaluate the location of screws and bone union at follow-up.
Results Fig. 1. Compared with the previously developed single-hole guide tube among percutaneous instruments (Left), our novel guide tube has two holes (Right).
Percutaneous anterior odontoid screw fixation was performed successfully in all of the 16 patients in which the initial K-wire trajectory was imperfect. The mean operative time
A.-M. Wu et al. / The Spine Journal 15 (2015) 1141–1145
1143
Fig. 2. The angle of the first K-wire was imperfect, angling slightly back on the (A) lateral view and leaning to the left on the (B) anteroposterior view. When aided by the two-hole guide tube, the second K-wire was inserted into the second hole of the guide tube. (C and D) By referring to the initial misplaced K-wire, an optimal trajectory for the second K-wire was achieved. (E and F) Finally, the odontoid screw was introduced along the second ideally placed K-wire.
was 31611 minutes, and none of the patients experienced blood loss exceeding 20 mL. All of the patients were followed-up for an average of 24.6 months (range, 12–39 months). No technique-related complications occurred. Satisfactory results and good screw placement were achieved in all patients (Fig. 3). Radiographic fusion was confirmed in 15 of 16 patients (Fig. 3), and a fracture line could be observed in one patient on sagittal reconstruction CT scans. Neither clinical symptoms nor screw loosening or breakage had occurred in any patient by the last follow-up.
Discussion Traditional open anterior odontoid screw fixation was widely used to treat odontoid fractures [11–13]. However, the extensive dissection and exposure associated with the traditional open technique increase patients’ risk of injury to adjacent nerves and blood vessels and considerable scarring. The technique of minimally invasive spinal surgery has developed rapidly in the recent decades. Percutaneous anterior odontoid screw fixation was reported by Kazan
1144
A.-M. Wu et al. / The Spine Journal 15 (2015) 1141–1145
Fig. 3. (Left and Middle) Computed tomography images taken at 24-month follow-up showed that bone union was achieved, and (Left, Middle, and Right) the position of the odontoid screw could be observed clearly.
et al. [8] in a cadaveric study and by Chi et al. [9] in a clinical investigation and was reported to offer the advantages of being minimally invasive, minimizing blood loss, and lead to a quick recovery [10]. If the initial K-wire is not positioned at an optimal angle, the existence of the initial hole makes it difficult to drill another K-wire trajectory. This is because the K-wire will enter into the initial suboptimal hole. Forceful direct drilling for the second optimal K-wire is time-consuming and increases patients’ and surgeons’ exposure to radiation. If such an approach fails, the amount of surgical time devoted to the approach is wasted. If the misplaced K-wire continues to follow the same trajectory and the odontoid screw is introduced along the misplaced K-wire, iatrogenic vascular or nerve injury may occur [14,15]. To avoid these complications, traditional open anterior odontoid screw fixation may be recommended by some surgeons, to lengthen the skin wound and perform extensive dissection and exposure until the anteroinferior region of C2 is visible. However, with the help of our novel two-hole guide tube, traditional open anterior odontoid screw fixation is not necessary and a second optimal K-wire trajectory can be easily drilled. Surgeons do not need to remove the first misplaced K-wire, because when the initial suboptimal K-wire hole is occupied by the initial K-wire, the second K-wire will not reenter the initial K-wire hole. Moreover, the initial K-wire could be used as reference for the second K-wire. Important to note is that the tip of the guide tube must be pressed tightly to the front of the vertebra to avoid allowing soft tissue to enter the space between the tip of the guide tube and the vertebra, which would result in injury by the K-wire. In addition, the accurate trajectory of the K-wire using the two-hole guide tube guarantees an accurate trajectory for odontoid screw placement. The challenging learning curve and potential risk for iatrogenic injury with error in the screw trajectory limit the wide clinical application of percutaneous anterior screw fixation. The novel two-hole
guide tube presented here may be helpful for promoting a quicker learning curve among surgeons and more accurate screw trajectories.
Conclusion Our novel device, two-hole guide tube, resolves the difficulty associated with redrilling a second optimal K-wire trajectory if the initial trajectory was imperfect for percutaneous anterior odontoid screw fixation. By referring to the initial misplaced K-wire, a more accurate trajectory for the second K-wire can be achieved.
Acknowledgments The manuscript submitted does not contain information about medical drug(s). This work is supported by National Natural Science Foundation of China (81372014, 81371988), Natural Science Foundation of Zhejiang Province (R12H060002, LY14H060008), and Qianjiang Talents Project of Technology Office of Zhejiang Province (2010R10075). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. References [1] Anderson LD, D’Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am 1974;56:1663–74. [2] Chapman J, Smith JS, Kopjar B, Vaccaro AR, Arnold P, Shaffrey CI, et al. The AOSpine North America geriatric odontoid fracture mortality study: a retrospective review of mortality outcomes for operative versus non-operative treatment in 322 patients with long-term followup. Spine 2013;38:1098–104. [3] Lewis E, Liew S, Dowrick A. Risk factors for non-union in the nonoperative management of type II dens fractures. ANZ J Surg 2011;81: 604–7. [4] Koivikko MP, Kiuru MJ, Koskinen SK, Myllynen P, Santavirta S, Kivisaari L. Factors associated with nonunion in conservatively-
A.-M. Wu et al. / The Spine Journal 15 (2015) 1141–1145
[5]
[6] [7] [8]
[9]
[10]
treated type-II fractures of the odontoid process. J Bone Joint Surg Br 2004;86:1146–51. Kim DH, Vaccaro AR, Affonso J, Jenis L, Hilibrand AS, Albert TJ. Early predictive value of supine and upright X-ray films of odontoid fractures treated with halo-vest immobilization. Spine J 2008;8: 612–8. Bohler J. Anterior stabilization for acute fractures and non-unions of the dens. J Bone Joint Surg Am 1982;64:18–27. Rajasekaran S, Kamath V, Avadhani A. Odontoid anterior screw fixation. Eur Spine J 2010;19:339–40. Kazan S, Tuncer R, Sindel M. Percutaneous anterior odontoid screw fixation technique. A new instrument and a cadaveric study. Acta Neurochir (Wien) 1999;141:521–4. Chi YL, Wang XY, Xu HZ, Lin Y, Huang QS, Mao FM, et al. Management of odontoid fractures with percutaneous anterior odontoid screw fixation. Eur Spine J 2007;16:1157–64. Wang J, Zhou Y, Zhang ZF, Li CQ, Zheng WJ, Liu J. Comparison of percutaneous and open anterior screw fixation in the treatment of
[11]
[12]
[13]
[14]
[15]
1145
type II and rostral type III odontoid fractures. Spine 2011;36: 1459–63. Konieczny MR, Gstrein A, Muller EJ. Treatment algorithm for dens fractures: non-halo immobilization, anterior screw fixation, or posterior transarticular C1-C2 fixation. J Bone Joint Surg Am 2012;94. e144(1-6). Daniels AH, Magee W, Badra M, Bay B, Hettwer W, Hart RA. Preliminary biomechanical proof of concept for a hybrid locking plate/variable pitch screw construct for anterior fixation of type II odontoid fractures. Spine 2012;37:E1159–64. Henaux PL, Cueff F, Diabira S, Riffaud L, Hamlat A, Brassier G, et al. Anterior screw fixation of type IIB odontoid fractures in octogenarians. Eur Spine J 2012;21:335–9. Wilson DA, Fusco DJ, Theodore N. Delayed subarachnoid hemorrhage following failed odontoid screw fixation. J Neurosurg Spine 2011;14:715–8. Inamasu J, Guiot BH. Vascular injury and complication in neurosurgical spine surgery. Acta Neurochir (Wien) 2006;148:375–87.
Technical Report
A novel technique of two-hole guide tube for percutaneous anterior odontoid screw fixation Ai-Min Wu, MD, Xiang-Yang Wang, MD PhD*, Dong-Dong Xia, MD, Peng Luo, MD, Hua-Zi Xu, MD, Yong-Long Chi, MD The Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# XueYuan Western Rd, Wenzhou, Zhejiang, 325027, People’s Republic of China Received 14 January 2014; revised 12 November 2014; accepted 3 February 2015
Abstract
BACKGROUND CONTEXT: Surgical stabilization is recommended for odontoid fractures with mechanical instability. Compared with C1–C2 fusion, percutaneous anterior odontoid screw fixation has the advantages of preserving C1/C2 motion and being a minimally invasive procedure. However, determining the optimal screw trajectory is often difficult. When an initial suboptimal K-wire hole is drilled, it is especially difficult to drill a second optimal K-wire trajectory because the initial hole will be entered inadvertently. PURPOSE: To design a novel device, two-hole guide tube, to make drilling a second optimal Kwire trajectory easier, and thus, avoid unnecessary additional surgical time and reduce the likelihood of needing to change the procedure to traditional open surgery. STUDY DESIGN: A technical report. METHODS: Fifty-three patients with odontoid fractures were treated by percutaneous anterior odontoid screw fixation in our hospital, and the initial K-wire trajectories of 16 cases (12 men and 4 women) among the 53 patients were imperfect. The two-hole guide tube was applied for drilling the second trajectory in each of these 16 cases. RESULTS: No complications associated with this technique occurred. Satisfactory results and good screw placement was achieved in all patients. Radiographic fusion was confirmed for 15 of 16 patients. None of the patients experienced clinical symptoms or screw loosening or breakage in this study. CONCLUSIONS: Our novel device, two-hole guide tube, can be used to reduce the difficulty associated with redrilling an optimal K-wire trajectory if the initial trajectory is imperfect during percutaneous anterior odontoid screw fixation. Moreover, by referring to the initial misplaced K-wire, a more accurate trajectory for the second K-wire can be achieved. Ó 2015 Elsevier Inc. All rights reserved.
Keywords:
Odontoid fracture; Guide tube; K-wire; Trajectory; Percutaneous; Minimally invasive; Technique note
Introduction FDA device/drug status: Not applicable. Author disclosures: A-MW: Nothing to disclose. X-YW: Nothing to disclose. D-DX: Nothing to disclose. PL: Nothing to disclose. H-ZX: Nothing to disclose. Y-LC: Nothing to disclose. This work was supported by the National Natural Science Foundation of China and Zhejiang Province. The authors declare that they have no conflicts of interest. * Corresponding author. The Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, Wenzhou, Zhejiang, People’s Republic of China. Tel.: (86) 0577-88002814; fax: (86) 0577-88002823. E-mail address: [email protected] (X.-Y. Wang) http://dx.doi.org/10.1016/j.spinee.2015.02.013 1529-9430/Ó 2015 Elsevier Inc. All rights reserved.
Odontoid fracture is a common injury in the upper cervical spine. Type II fractures and shallow Type III odontoid fractures (according to the classification of Anderson and D’Alonzo [1]) are mechanically unstable and are associated with a high risk of nonunion or mortality [2–4]. Thus, surgical stabilization is recommended for these patients [5]. Anterior odontoid screw fixation was first reported in the early 1980s [6]. Compared with C1–C2 fusion, this approach offers the advantage of preserving C1/C2 motion [7]. Moreover, the anterior odontoid screw can be inserted
1142
A.-M. Wu et al. / The Spine Journal 15 (2015) 1141–1145
percutaneously [8,9], which allows this approach to be minimally invasive and associated with reduced blood loss, quicker recovery, and shorter hospital stay compared with the traditional open surgery [10]. However, the surgical procedure for percutaneous anterior odontoid screw fixation is not always successful, and in some cases, it is difficult to determine the ideal screw trajectory on both anteroposterior (AP) and lateral views with C-arm simultaneously. Especially, when an initial suboptimal K-wire trajectory is drilled, it is difficult to redrill another optimal K-wire trajectory because the initial hole will be entered inadvertently. If another optimal K-wire trajectory cannot be drilled, it is impossible to introduce the anterior odontoid screw percutaneously. For this reason, some surgeons give up on the percutaneous technique and perform the traditional open technique. To overcome the difficulty associated with drilling an optimal second hole, we designed a novel device, which we refer to as the ‘‘two-hole guide tube’’ (Fig. 1). An optimal K-wire trajectory is known to be necessary for achieving a perfect odontoid screw trajectory because the screw is introduced along the K-wire [9]. Therefore, the optimal K-wire trajectory is very important and directly influences the success of percutaneous anterior odontoid screw fixation. Here, we describe the results of 16 operations performed using the two-hole guide tube.
Methods and materials Patient population Between January 2009 and February 2011, 53 patients with odontoid fractures were treated by percutaneous anterior odontoid screw fixation in our hospital. In 16 of these patients (12 men and 4 women), the initial K-wire trajectories were imperfect and drilling of a second more optimal
K-wire trajectory was necessary. Fourteen cases were Type II odontoid fractures and two were shallow Type III fractures according to the classification system established by Anderson and D’Alonzo [1]. Patient’s age ranged from 29 to 64 years (mean, 39.4 years). We used our novel twohole guide tube in these 16 patients. Preoperative lateral and AP (open-mouth) views and computed tomography (CT) scans were obtained to evaluate the feasibility of surgery. Surgical technique The general procedure followed for percutaneous anterior odontoid screw fixation was the same as that previously described by Chi et al. [9]. Briefly, patients were placed supine on the operating table, and anatomic reduction was achieved using Gardner-Wells skull traction tongs. An initial 5- to 10-mm incision was made medial to the right sternocleidomastoid muscle at the level of C4–C5 disc space, and blunt dissection was performed to reach the anterior border of the spinal column using the finger or hemostat. A protective tube was inserted first and then the guide tube was inserted inside the protective tube. The tip of the guide tube was placed anteroinferior to C2. The K-wire was drilled into the odontoid process, and the angle and position of the K-wire were confirmed by intraoperative fluoroscopic AP and lateral views. If the K-wire trajectory was confirmed to be imperfect (Fig. 2), we did not remove this imperfect K-wire immediately. While the previous one-hole guide tube was being removed and the two-hole guide tube was being applied, the initial, imperfectly placed K-wire was passed through one-hole of the two-hole guide tube and another K-wire was inserted through the other hole of the two-hole guide tube. Then, we adjusted the second K-wire to an optimal angle and trajectory referring to the initial, imperfectly inserted K-wire (Fig. 2), the initial imperfect K-wire and guide tube were removed after the second optimal K-wire trajectory was drilled. A recess for the screw head was fashioned with a cannulated drill bit along the second K-wire, and finally, the odontoid screw was introduced along the second K-wire (Fig. 2). After both the second K-wire and the guide tube were removed, the wound was checked for hemostasis and suture closure. Patients were allowed ambulatory activities on postoperative Day 2 with a cervical collar that was removed at 12 weeks after surgery. Postoperative lateral and AP (openmouth) views and CT scans were obtained to evaluate the location of screws and bone union at follow-up.
Results Fig. 1. Compared with the previously developed single-hole guide tube among percutaneous instruments (Left), our novel guide tube has two holes (Right).
Percutaneous anterior odontoid screw fixation was performed successfully in all of the 16 patients in which the initial K-wire trajectory was imperfect. The mean operative time
A.-M. Wu et al. / The Spine Journal 15 (2015) 1141–1145
1143
Fig. 2. The angle of the first K-wire was imperfect, angling slightly back on the (A) lateral view and leaning to the left on the (B) anteroposterior view. When aided by the two-hole guide tube, the second K-wire was inserted into the second hole of the guide tube. (C and D) By referring to the initial misplaced K-wire, an optimal trajectory for the second K-wire was achieved. (E and F) Finally, the odontoid screw was introduced along the second ideally placed K-wire.
was 31611 minutes, and none of the patients experienced blood loss exceeding 20 mL. All of the patients were followed-up for an average of 24.6 months (range, 12–39 months). No technique-related complications occurred. Satisfactory results and good screw placement were achieved in all patients (Fig. 3). Radiographic fusion was confirmed in 15 of 16 patients (Fig. 3), and a fracture line could be observed in one patient on sagittal reconstruction CT scans. Neither clinical symptoms nor screw loosening or breakage had occurred in any patient by the last follow-up.
Discussion Traditional open anterior odontoid screw fixation was widely used to treat odontoid fractures [11–13]. However, the extensive dissection and exposure associated with the traditional open technique increase patients’ risk of injury to adjacent nerves and blood vessels and considerable scarring. The technique of minimally invasive spinal surgery has developed rapidly in the recent decades. Percutaneous anterior odontoid screw fixation was reported by Kazan
1144
A.-M. Wu et al. / The Spine Journal 15 (2015) 1141–1145
Fig. 3. (Left and Middle) Computed tomography images taken at 24-month follow-up showed that bone union was achieved, and (Left, Middle, and Right) the position of the odontoid screw could be observed clearly.
et al. [8] in a cadaveric study and by Chi et al. [9] in a clinical investigation and was reported to offer the advantages of being minimally invasive, minimizing blood loss, and lead to a quick recovery [10]. If the initial K-wire is not positioned at an optimal angle, the existence of the initial hole makes it difficult to drill another K-wire trajectory. This is because the K-wire will enter into the initial suboptimal hole. Forceful direct drilling for the second optimal K-wire is time-consuming and increases patients’ and surgeons’ exposure to radiation. If such an approach fails, the amount of surgical time devoted to the approach is wasted. If the misplaced K-wire continues to follow the same trajectory and the odontoid screw is introduced along the misplaced K-wire, iatrogenic vascular or nerve injury may occur [14,15]. To avoid these complications, traditional open anterior odontoid screw fixation may be recommended by some surgeons, to lengthen the skin wound and perform extensive dissection and exposure until the anteroinferior region of C2 is visible. However, with the help of our novel two-hole guide tube, traditional open anterior odontoid screw fixation is not necessary and a second optimal K-wire trajectory can be easily drilled. Surgeons do not need to remove the first misplaced K-wire, because when the initial suboptimal K-wire hole is occupied by the initial K-wire, the second K-wire will not reenter the initial K-wire hole. Moreover, the initial K-wire could be used as reference for the second K-wire. Important to note is that the tip of the guide tube must be pressed tightly to the front of the vertebra to avoid allowing soft tissue to enter the space between the tip of the guide tube and the vertebra, which would result in injury by the K-wire. In addition, the accurate trajectory of the K-wire using the two-hole guide tube guarantees an accurate trajectory for odontoid screw placement. The challenging learning curve and potential risk for iatrogenic injury with error in the screw trajectory limit the wide clinical application of percutaneous anterior screw fixation. The novel two-hole
guide tube presented here may be helpful for promoting a quicker learning curve among surgeons and more accurate screw trajectories.
Conclusion Our novel device, two-hole guide tube, resolves the difficulty associated with redrilling a second optimal K-wire trajectory if the initial trajectory was imperfect for percutaneous anterior odontoid screw fixation. By referring to the initial misplaced K-wire, a more accurate trajectory for the second K-wire can be achieved.
Acknowledgments The manuscript submitted does not contain information about medical drug(s). This work is supported by National Natural Science Foundation of China (81372014, 81371988), Natural Science Foundation of Zhejiang Province (R12H060002, LY14H060008), and Qianjiang Talents Project of Technology Office of Zhejiang Province (2010R10075). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. References [1] Anderson LD, D’Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am 1974;56:1663–74. [2] Chapman J, Smith JS, Kopjar B, Vaccaro AR, Arnold P, Shaffrey CI, et al. The AOSpine North America geriatric odontoid fracture mortality study: a retrospective review of mortality outcomes for operative versus non-operative treatment in 322 patients with long-term followup. Spine 2013;38:1098–104. [3] Lewis E, Liew S, Dowrick A. Risk factors for non-union in the nonoperative management of type II dens fractures. ANZ J Surg 2011;81: 604–7. [4] Koivikko MP, Kiuru MJ, Koskinen SK, Myllynen P, Santavirta S, Kivisaari L. Factors associated with nonunion in conservatively-
A.-M. Wu et al. / The Spine Journal 15 (2015) 1141–1145
[5]
[6] [7] [8]
[9]
[10]
treated type-II fractures of the odontoid process. J Bone Joint Surg Br 2004;86:1146–51. Kim DH, Vaccaro AR, Affonso J, Jenis L, Hilibrand AS, Albert TJ. Early predictive value of supine and upright X-ray films of odontoid fractures treated with halo-vest immobilization. Spine J 2008;8: 612–8. Bohler J. Anterior stabilization for acute fractures and non-unions of the dens. J Bone Joint Surg Am 1982;64:18–27. Rajasekaran S, Kamath V, Avadhani A. Odontoid anterior screw fixation. Eur Spine J 2010;19:339–40. Kazan S, Tuncer R, Sindel M. Percutaneous anterior odontoid screw fixation technique. A new instrument and a cadaveric study. Acta Neurochir (Wien) 1999;141:521–4. Chi YL, Wang XY, Xu HZ, Lin Y, Huang QS, Mao FM, et al. Management of odontoid fractures with percutaneous anterior odontoid screw fixation. Eur Spine J 2007;16:1157–64. Wang J, Zhou Y, Zhang ZF, Li CQ, Zheng WJ, Liu J. Comparison of percutaneous and open anterior screw fixation in the treatment of
[11]
[12]
[13]
[14]
[15]
1145
type II and rostral type III odontoid fractures. Spine 2011;36: 1459–63. Konieczny MR, Gstrein A, Muller EJ. Treatment algorithm for dens fractures: non-halo immobilization, anterior screw fixation, or posterior transarticular C1-C2 fixation. J Bone Joint Surg Am 2012;94. e144(1-6). Daniels AH, Magee W, Badra M, Bay B, Hettwer W, Hart RA. Preliminary biomechanical proof of concept for a hybrid locking plate/variable pitch screw construct for anterior fixation of type II odontoid fractures. Spine 2012;37:E1159–64. Henaux PL, Cueff F, Diabira S, Riffaud L, Hamlat A, Brassier G, et al. Anterior screw fixation of type IIB odontoid fractures in octogenarians. Eur Spine J 2012;21:335–9. Wilson DA, Fusco DJ, Theodore N. Delayed subarachnoid hemorrhage following failed odontoid screw fixation. J Neurosurg Spine 2011;14:715–8. Inamasu J, Guiot BH. Vascular injury and complication in neurosurgical spine surgery. Acta Neurochir (Wien) 2006;148:375–87.
