eO
RIGINAL
ARTICLE
Anterior Cervical Discectomy and Fusion Versus Posterior Fixation and Fusion of C2–3 for Unstable Hangman’s Fracture Chaoyuan Ge, MD,* Dingjun Hao, MD,* Baorong He, MD,* and Baibing Mi, MDw
Study Design: This was a retrospective study.
Key Words: hangman’s fracture, traumatic spondylolisthesis of axis, anterior approach, posterior approach, fusion
Objective: To compare the efficacy and safety between anterior cervical discectomy and fusion (ACDF) and posterior fixation and fusion (PFF) for treating unstable hangman’s fracture.
(J Spinal Disord Tech 2015;28:E61–E66)
Summary of Background Data: In previous clinical study, ACDF and PFF have been introduced to manage unstable hangman’s fracture. However, it remains unknown which approach is superior.
H
Methods: Between January 2006 and May 2011, 44 patients with unstable hangman’s fracture underwent either ACDF or PFF. The operation time, blood loss, surgical complications, and postoperative drainage were compared. Neurologic function was evaluated using the ASIA scale and neck pain was assessed using the Visual Analogue Scale (VAS) score. Rates of fracture heeling and bone fusion were also studied. Results: Follow-up was completed for 38 patients. Twenty-four cases underwent ACDF and 14 cases received PFF. The operation was successful in all 38 cases. The mean operative time, estimated blood loss, and postoperative drainage were significantly shorter or less for the ACDF group than the PFF group (P < 0.01). No surgical complication was reported in the ACDF group. Excessive bleeding due to injury to the venous plexus occurred in 3 cases in the PFF group. The VAS score in the 2 groups was significantly lower than their respective preoperative score (P < 0.01), but there was no difference between the 2 groups (P > 0.05). Solid fusion was achieved with no implant failure in all cases 6 months postoperatively. At the final follow-up, 8 cases with ASIA C or D grade improved to E grade. Conclusions: The anterior procedure seems to be superior to the posterior approach for unstable hangman’s fracture as it is a less invasive and simpler procedure with fewer complications and is especially indicated for cases with no medullary canal in C2 pedicles and traumatic C2–3 disk herniation compressing the spinal cord. Received for publication January 15, 2014; accepted June 10, 2014. From the *Department of Spinal Surgery, Honghui Hospital, Xi’an Jiaotong University Health Science Center; and wDepartment of Statistics and Epidemiology, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, People’s Republic of China. The authors declare no conflict of interest. Reprints: Dingjun Hao, MD, Department of Spinal Surgery, Honghui Hospital, Xi’an Jiaotong University Health Science Center, No.555 Youyi East Road, Xi’an, 710054, Shaanxi, People’s Republic of China (e-mail: [email protected]). Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved.
J Spinal Disord Tech
Volume 28, Number 2, March 2015
angman’s fracture, also known as traumatic spondylolisthesis of the axis, is defined as a fracture of bilateral C2 pars interarticularis, with a variable degree of displacement and angulation of C2 on the C3 vertebra.1 It is the second most common fracture of the C2 vertebra and accounts for 4%–7% of all cervical spine fractures2 and 23%–27% of axis fractures.3 According to the classification of Levine-Edwards,4 type II, IIa, and III hangman’s fractures are unstable as they usually have ruptures of the C2/3 disk as well as of the anterior and posterior longitudinal ligament. Nonoperative treatment of these injuries is associated with a significant rate of stabilization failure, delayed union, or residual neck pain.5–7 Surgical intervention as a primary management avoids risks inherent in conservative management and reduces the risk of catastrophic results at the fracture site and, therefore, is usually preferable in the treatment of unstable hangman’s fracture.8 Currently available surgical options include anterior cervical discectomy and fusion (ACDF) at C2–3, posterior C2 transpedicle screws, posterior fixation and fusion (PFF), and C1–3 lateral mass screws.9–12 Although C2 transpedicle screws directly address the detached posterior arch and preserve C2 motion, they fail to tackle segmental instability of C2–3.10 C1–3 fixation and fusion eliminates atlantoaxial motor function, which accounts for more than half of cervical spine motion13 and is considered overtreatment. ACDF and PFF are often applied to these fractures, with satisfactory outcomes.10,12 However, it remains unknown whether ACDF is superior to PFF or vice versa as there is no comparative study on the noninferiority of the 2 different surgical approaches. In the present study, we retrospectively reviewed the surgical records of patients with hangman’s fracture who had undergone ACDF or PFF at our institution and compared the efficacy and safety of these 2 fixation techniques.
METHODS Patients We reviewed the surgical records of 44 patients with hangman’s fracture who were admitted to our tertiary www.jspinaldisorders.com |
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care hospital between January 2006 and May 2011. Hangman’s fracture was classified according to the Levine-Edwards classification system.4 Follow-up was completed for 38 patients: 24 cases in the ACDF and 14 cases in the PFF. The study protocol was approved by the local institutional review board at the authors’ affiliated institution. The present study was conducted in accordance with the Declaration of Helsinki and with approval from the Ethics Committee of the Hong Hui Hospital. All persons gave their informed consent before their inclusion in the study.
Surgical Techniques All operations were performed by 2 similarly experienced surgeons with >20 years of experience in spine surgery and operations were performed at a single hospital. In our study, 5 cases with traumatic C2–3 disk herniation compressing the spinal cord and 2 cases of no medullary canal in C2 pedicles, confirmed by preoperative CT and MRI, were undergoing ACDF, whereas surgical procedures for the rest of patients depended on involved surgeons’ policies, not the class of fracture. Routine preoperative skull traction was performed in all patients. A weight of 2–4 kg at an appropriate angle was applied to stabilize and reduce fracture. All patients received general anesthesia by endotracheal intubation. For patients who received ACDF, the surgical procedure was performed as described by Tuite et al.14 The patient was placed in the supine position with neck slightly extended. A standard anterior horizontal incision was made midway between angle of the jaw and the thyroid cartilage. Discectomy was performed routinely, and the posterior longitudinal ligament was removed to achieve thorough decompression. Fusion of C2–3 was performed by placing a PEEK cage filled with bone substitute, supplemented with an anterior self-locking plate. For patients who underwent PFF, the operative procedure was similar to Ma et al’s procedure.10 The patient was placed in prone position, with head resting in a clamp. The upper cervical spine was routinely exposed. The entry point for C2 pedicle screws was the superior and medial quadrant of the isthmus of C2, with the insertion angle about 20 degrees medial and 25 degrees superior. The entry point of C3 lateral mass screw was the center of the C3 articular mass, with the insertion angle 20 degrees outward in the transverse plane. The cortex was penetrated at the insertion point by a high-speed spherical burr, and screws were then inserted smoothly. Suitable rods were selected, bent, and then connected to the screws with locking caps. The cartilage surfaces of the C2–3 articular process were decorticated, and bone substitute was placed in these areas. The wound was closed in standard manner under suction drainage in all patients. Postoperative immobilization was achieved with a hard collar for 3 months.
Patient Evaluation The operation time, blood loss, surgical complications, and postoperative drainage were recorded for all
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patients. The neurological functioning of patients was evaluated using the ASIA scale.15 Standard anteroposterior and lateral radiographs of the cervical spine were obtained and computed tomography (CT) with bone window of the entire cervical spine and sagittal reconstruction were also undertaken preoperatively. In addition, preoperative cervical spine magnetic resonance imaging (MRI) was performed. X-ray, CT, and MRI were also performed on the third postoperative day, at 3 and 6 months postoperatively, and then every 6 months thereafter to assess the improvement of neurological function, cervical spine motion, and the rate of fracture heeling and bone fusion. The VAS score of patients in the 2 groups were analyzed preoperatively and 3 months after surgery. The primary endpoints of this analysis were anatomic reduction rate and changes in ASIA grade.
Statistical Analysis Statistical analysis was performed using SPSS 18.0 (SPSS Inc., Chicago, IL). Two-sample t test for independent samples was used to analyze differences in operation time, blood loss, and postoperative drainage between the 2 groups. A P-value 0.05).
Surgical Outcomes The operation was successful in all 38 cases. No intraoperative or postoperative spinal cord or vertebral artery injury was observed. The mean operative time was 87 ± 8 (range, 75–110) minutes for the ACDF group, Copyright
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2014 Wolters Kluwer Health, Inc. All rights reserved.
J Spinal Disord Tech
Volume 28, Number 2, March 2015
TABLE 1. Demographic and Baseline Characteristics of Patients Receiving ACDF or PFF in the Study All
ACDF
PFF
N (%) 38 (100) 24 (63.2) 14 (36.8) Age (y) Mean (SD) 38.1 (8.6) 36.5 (7.8) 39.6 (8.1) Range 19–65 19–52 22–65 Sex [n (%)] Male 25 (65.8) 16 (66.7) 9 (64.3) Mechanisms of injury (%) Vehicle accidents 28 (73.7) 18 (75) 10 (71.4) Falls 7 (18.4) 4 (16.7) 3 (21.4) Hits 3 (7.9) 2 (8.3) 1 (7.1) Levine-Edwards classification [n (%)] II 21 (55.3) 13 (54.2) 8 (57.1) IIa 15 (39.5) 9 (37.5) 6 (42.9) III 2 (5.3) 2 (8.3) 0 (0) Combined injury [n (%)] Head injury 16 (39.5) 9 (37.5) 6 (42.9) Facial soft tissue injury 13 (34.2) 7 (29.2) 6 (42.9) Thoraco-lumbar spine fracture 6 (15.8) 4 (16.7) 2 (14.3) Lower cervical spine fracture 5 (13.2) 4 (16.7) 1 (7.1) Fracture of extremities 5 (13.2) 3 (12.5) 2 (14.3) Left clavicle fracture 2 (5.3) 2 (8.3) 0 (0) Fracture of the mandible 2 (5.3) 1 (4.2) 1 (7.1) Neurologic deficits (ASIA) [n (%)] C 2 (5.3) 1 (4.2) 1 (7.1) D 6 (15.8) 5 (20.8) 1 (7.1) VAS Mean (SD) 5.6 (2.8) 5.3 (1.8) 5.8 (2.1) ACDF indicates anterior cervical discectomy and fusion; PFF, posterior fixation and fusion; VAS, visual analogue scale.
which was markedly shorter than that of the PFF group (mean, 149 ± 14 min; range, 120–165 min) (P < 0.01). The mean estimated blood loss was 111 ± 22 (range, 90–130) mL for the ACDF group, which was significantly less than that of the PFF group (mean, 198 ± 15 mL; range, 160–210 mL) (P < 0.01). The mean postoperative drainage was 26 ± 9 (range, 20–45) mL for the ACDF group, which was markedly lower than that of the PFF group (mean, 66 ± 7 mL; range, 55–80 mL) (P < 0.01) (Table 2). No surgical complication was reported in the ACDF group. Excessive bleeding due to injury to the venous plexus occurred in 3 cases during surgery in the PFF group, which were treated with gelatin sponge compression without development of late sequelae.
Primary and Secondary Outcomes The patients were followed up for a mean duration of 42 (range, 24–60) months. The VAS score postoperatively in the ACDF and PFF group was 1.8 ± 0.9 and 1.6 ± 0.8, respectively, which was significantly lower than their respective preoperative VAS scores (P < 0.01), but there was no difference between the 2 groups (P > 0.05). Lateral x-ray image demonstrated that solid fusion was achieved with no implant failure in all cases at the 6-month follow-up visit (Figs. 1B, 2A). At the final follow-up, 8 cases with ASIA C or D grade improved to ASIA E. No patient complained of limited mobility of cervical spine in flexion, extension, and rotation. Copyright
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2014 Wolters Kluwer Health, Inc. All rights reserved.
ACDF for Unstable Hangman’s Fracture
TABLE 2. Comparison of Operative Variables Between the ACDF and PFF Group Variables
ACDF (n = 24)
Operation time (min) Mean (SD) 87 (8) Range 75–110 Estimated blood loss (mL) Mean (SD) 111 (22) Range 90–130 Postoperative drainage (mL) Mean (SD) 26 (9) Range 20–45
PFF (n = 14)
t
P
149 (14) 120–165
17.712
< 0.01
198 (15) 160–210
13.344
< 0.01
66 (7) 55–80
14.571
< 0.01
ACDF indicates anterior cervical discectomy and fusion; PFF, posterior fixation and fusion; VAS, visual analogue scale.
DISCUSSION Unstable hangman’s fracture has a high number of concomitant injuries and is labile to neurological compromise and development of significant complications associated with nonoperative treatment.16,17 Surgical stabilization is recommended in Levine-Edwards type IIa and type III fractures with significant dislocation.8 Our study demonstrates that both ACDF and PFF are effective for solid bony fusion and improve patient symptoms. Meanwhile, ACDF is a less invasive and simpler procedure with a shorter operative time. The estimated blood loss and postoperative drainage are also lower. Neurologic deterioration of unstable hangman’s fracture rarely occurs because of the decompressive nature of the injury itself and the ample space available for the cord in the upper cervical spine.18 The rate of spinal cord injury in our study was 21.1% (8/38), which is higher than the previously reported rate of 6% to 10%.16,19 Ruptures of the C2–3 disk, the anterior and posterior longitudinal ligament, were confirmed during execution of the anterior procedure. Hangman’s fracture usually occurs through the superior facet joint, in an area of wellvascularized spongy cancellous bone.20 The posterior approach needs to dissect the posterior cervical muscles. Furthermore, excessive bleeding due to injury to the venous plexus occurred in 3 cases in the PFF group. All these reasons may explain why the posterior approach has a longer operative time and greater estimated blood loss and postoperative drainage. As Roy-Camille et al21 first described C2–3 posterior screw-plate fixation by connecting screws inserted into fractured C2 pedicle with C3 lateral masse, PFF of C2–3 has become increasingly popular.10,22 The advantage of this procedure is direct fixation of the pars interarticularis fracture of C2 with a simple process for exposure.10 However, visible injuries to the anterior ligament and disk are neglected with a potential risk of instability.23 Moreover, the highly variable anatomy of the upper cervical spine and the presence of surrounding neurovascular structures, such as the spinal cord, nerve roots, and vertebral artery, make posterior screw fixation technically challenging, especially the insertion of C2 pedicle screws. The accuracy of C2 pedicle screws www.jspinaldisorders.com |
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FIGURE 1. A 33-year old man sustained a type II hangman’s fracture in a vehicle accident. A, Preoperative lateral x-ray image showing a apparent displacement of C2 on C3. B, Postoperative lateral x-ray image showing C2–3 fusion with a PEEK cage filled with bone substitute and anterior plate fixation.
placement cannot be guaranteed yet, even under intraoperative 3-dimensional fluoroscopy-based navigation.22 In our study, postoperative axial CT scan indicated that 5 C2 pedicle screws minimally invaded the spinal canal (Fig. 2B). The rate of misplaced screws of C2 pedicle was 17.9% (5/28), which correlates well with the published data (16.9%–21.6%).24,25 The occurrence of neurovascular injuries is very common in the posterior approach.10,22,26 As this is a high-risk procedure, many surgeons prefer the anterior approach. In our study, preoperative CT scan showed that 2 cases had no
medullary canal in C2 pedicles and chose the anterior surgery (Fig. 3). The lack of the medullary canal in C2 pedicles and too small and deformed C2 pedicle render screw placement difficult and are contraindicated for PFF. Liu et al27 believed that PFF for a highly unstable hangman’s fracture may aggravate forward displacement of C2 because of the intraoperative prone position and the forward thrust of the C2 screw, particularly with the extremely unstable state of C2. This aggravation causes iatrogenic injury and may lead to extremely negative consequences.
FIGURE 2. A 42-year-old man sustained a type II hangman’s fracture in a fall. A, Postoperative lateral x-ray image showing C2–3 fusion with C2 pedicle screws and C3 lateral mass screws. B, Axial scan of C2 showing a unilateral isthmus fracture associated with the fracture of the body of C2 and the right side of C2 pedicle screw slightly invades the spinal canal.
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Copyright
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2014 Wolters Kluwer Health, Inc. All rights reserved.
J Spinal Disord Tech
Volume 28, Number 2, March 2015
ACDF for Unstable Hangman’s Fracture
approach offers patients reliable primary stability, anatomic reduction with reconstruction of cervical spine, favorable clinical outcome, and avoidance of secondary salvage fusion after failure of primary conservative treatment.29 Good clinical outcomes and no surgical complications in the ACDF group certify that the anterior procedure is a relatively effective and safe surgical procedure to manage the unstable hangman’s fracture.
CONCLUSIONS In conclusion, both the anterior and posterior approach are effective for unstable hangman’s fracture with solid bony fusion, satisfactory improvement of neck pain, neurologic status, and cervical spine motion. The anterior procedure seems to be superior as it is a less invasive and simpler procedure with fewer complications and is especially indicated for cases with no medullary canal in C2 pedicles and traumatic C2–3 disk herniation compressing the spinal cord. However, the current study is limited by its retrospective nature and small number of patients. The conclusion of the study requires further confirmation by prospective studies involving more cases. REFERENCES
FIGURE 3. Preoperative axial scan of C2 showing that there is no medullary canal in the right side of C2 pedicle.
The anterior cervical plate technique, first proposed in the 1980s, has the advantage of excising the scathing disk-ligament complex, which has a potential risk of instability.23 It is also directly decompressive for the spinal cord by removal of the disk tissue in the spinal canal. In our study, 5 cases with traumatic C2–3 disk herniation compressing the spinal cord were treated with ACDF successfully and they all showed an apparent improvement of neurological function postoperatively. Tuite et al14 reported that a patient whose fracture was not reducible by closed techniques was found to have a large epidural hematoma. After the epidural hematoma was evacuated by draining through a tear in the posterior longitudinal ligament through the anterior procedure, spinal alignment was easily obtained. Some contraindications of PFF, such as lack of the medullary canal in C2 pedicles, too small and deformed C2 pedicle, are indications for the anterior operation. Moreover, the supine position and the procedure of placement of anterior plate and screws facilitate reduction of anterior displacement of C2 body. However, the anterior approach has disadvantages as well. The high anterior approach exposes important anatomic structures at risk, especially the facial and hypoglossal nerves, branches of the external carotid, the contents of the carotid sheath, and the superior laryngeal nerve.28 However, in skilled hands, the anterior Copyright
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2014 Wolters Kluwer Health, Inc. All rights reserved.
1. Effendi B, Roy D, Cornish B, et al. Fractures of the ring of the axis. A classification based on the analysis of 131 cases. J Bone Joint Surg Br. 1981;63-B:319–327. 2. Gehweiler JJ, Clark WM, Schaaf RE, et al. Cervical spine trauma: the common combined conditions. Radiology. 1979;130:77–86. 3. Greene KA, Dickman CA, Marciano FF, et al. Acute axis fractures. Analysis of management and outcome in 340 consecutive cases. Spine (Phila Pa 1976). 1997;22:1843–1852. 4. Levine AM, Edwards CC. The management of traumatic spondylolisthesis of the axis. J Bone Joint Surg Am. 1985;67:217–226. 5. Shin JJ, Kim SH, Cho YE, et al. Primary surgical management by reduction and fixation of unstable hangman’s fractures with discoligamentous instability or combined fractures. J Neurosurg Spine. 2013;19:569–575. 6. Vaccaro AR, Madigan L, Bauerle WB, et al. Early halo immobilization of displaced traumatic spondylolisthesis of the axis. Spine (Phila Pa 1976). 2002;27:2229–2233. 7. Watanabe M, Nomura T, Toh E, et al. Residual neck pain after traumatic spondylolisthesis of the axis. J Spinal Disord Tech. 2005; 18:148–151. 8. Li X, Dai L, Lu H, et al. A systematic review of the management of hangman’s fractures. Eur Spine J. 2006;15:257–269. 9. ElMiligui Y, Koptan W, Emran I. Transpedicular screw fixation for type II Hangman’s fracture: a motion preserving procedure. Eur Spine J. 2010;19:1299–1305. 10. Ma W, Xu R, Liu J, et al. Posterior short-segment fixation and fusion in unstable Hangman’s fractures. Spine (Phila Pa 1976). 2011;36:529–533. 11. Muthukumar N. C1-C3 lateral mass fusion for type IIa and type III Hangman’s fracture. J Craniovertebr Junction Spine. 2012;3:62–66. 12. Ying Z, Wen Y, Xinwei W, et al. Anterior cervical discectomy and fusion for unstable traumatic spondylolisthesis of the axis. Spine (Phila Pa 1976). 2008;33:255–258. 13. Dickman CA, Sonntag VK. Surgical management of atlantoaxial nonunions. J Neurosurg. 1995;83:248–253. 14. Tuite GF, Papadopoulos SM, Sonntag VK. Caspar plate fixation for the treatment of complex hangman’s fractures. Neurosurgery. 1992;30:761–764; discussion 764-5. 15. El MW, Tsubo M, Katoh S, et al. Validation of the American Spinal Injury Association (ASIA) motor score and the National Acute Spinal Cord Injury Study (NASCIS) motor score. Spine (Phila Pa 1976). 1996;21:614–619.
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16. Muller EJ, Wick M, Muhr G. Traumatic spondylolisthesis of the axis: treatment rationale based on the stability of the different fracture types. Eur Spine J. 2000;9:123–128. 17. Francis WR, Fielding JW, Hawkins RJ, et al. Traumatic spondylolisthesis of the axis. J Bone Joint Surg Br. 1981;63-B:313–318. 18. Seljeskog EL, Chou SN. Spectrum of the hangman’s fracture. J Neurosurg. 1976;45:3–8. 19. Buchowski JM, Riley LR. Epidural hematoma after immobilization of a “hangman’s” fracture: case report and review of the literature. Spine J. 2005;5:332–335. 20. Sherk HH, Howard T. Clinical and pathologic correlations in traumatic spondylolisthesis of the axis. Clin Orthop Relat Res. 1983;174:122–126. 21. Roy-Camille R, Saillant G, Mazel C. Internal fixation of the unstable cervical spine by a posterior osteosynthesis with plates and screws. Cervical Spine. 1989;25:390–403. 22. Tian W, Weng C, Liu B, et al. Posterior fixation and fusion of unstable Hangman’s fracture by using intraoperative three-dimensional fluoroscopy-based navigation. Eur Spine J. 2012;21:863–871. 23. Wang C, Ma H, Yuan W, et al. Anterior C3 corpectomy and fusion for complex Hangman’s fractures. Int Orthop. 2013;37:89–93.
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24. Yukawa Y, Kato F, Ito K, et al. Placement and complications of cervical pedicle screws in 144 cervical trauma patients using pedicle axis view techniques by fluoroscope. Eur Spine J. 2009;18:1293–1299. 25. Mueller CA, Roesseler L, Podlogar M, et al. Accuracy and complications of transpedicular C2 screw placement without the use of spinal navigation. Eur Spine J. 2010;19:809–814. 26. Ludwig SC, Kramer DL, Balderston RA, et al. Placement of pedicle screws in the human cadaveric cervical spine: comparative accuracy of three techniques. Spine (Phila Pa 1976). 2000;25: 1655–1667. 27. Liu J, Li Y, Wu Y. One-stage posterior C2 and C3 pedicle screw fixation or combined anterior C2-C3 fusion for the treatment of unstable hangman’s fracture. Exp Ther Med. 2013;5:667–672. 28. McAfee PC, Bohlman HH, Riley LJ, et al. The anterior retropharyngeal approach to the upper part of the cervical spine. J Bone Joint Surg Am. 1987;69:1371–1383. 29. Junge A, El-Sheik M, Celik I, et al. Pathomorphology, diagnosis and treatment of “hangman’s fractures”. Unfallchirurg. 2002;105: 775–782.
Copyright
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2014 Wolters Kluwer Health, Inc. All rights reserved.
RIGINAL
ARTICLE
Anterior Cervical Discectomy and Fusion Versus Posterior Fixation and Fusion of C2–3 for Unstable Hangman’s Fracture Chaoyuan Ge, MD,* Dingjun Hao, MD,* Baorong He, MD,* and Baibing Mi, MDw
Study Design: This was a retrospective study.
Key Words: hangman’s fracture, traumatic spondylolisthesis of axis, anterior approach, posterior approach, fusion
Objective: To compare the efficacy and safety between anterior cervical discectomy and fusion (ACDF) and posterior fixation and fusion (PFF) for treating unstable hangman’s fracture.
(J Spinal Disord Tech 2015;28:E61–E66)
Summary of Background Data: In previous clinical study, ACDF and PFF have been introduced to manage unstable hangman’s fracture. However, it remains unknown which approach is superior.
H
Methods: Between January 2006 and May 2011, 44 patients with unstable hangman’s fracture underwent either ACDF or PFF. The operation time, blood loss, surgical complications, and postoperative drainage were compared. Neurologic function was evaluated using the ASIA scale and neck pain was assessed using the Visual Analogue Scale (VAS) score. Rates of fracture heeling and bone fusion were also studied. Results: Follow-up was completed for 38 patients. Twenty-four cases underwent ACDF and 14 cases received PFF. The operation was successful in all 38 cases. The mean operative time, estimated blood loss, and postoperative drainage were significantly shorter or less for the ACDF group than the PFF group (P < 0.01). No surgical complication was reported in the ACDF group. Excessive bleeding due to injury to the venous plexus occurred in 3 cases in the PFF group. The VAS score in the 2 groups was significantly lower than their respective preoperative score (P < 0.01), but there was no difference between the 2 groups (P > 0.05). Solid fusion was achieved with no implant failure in all cases 6 months postoperatively. At the final follow-up, 8 cases with ASIA C or D grade improved to E grade. Conclusions: The anterior procedure seems to be superior to the posterior approach for unstable hangman’s fracture as it is a less invasive and simpler procedure with fewer complications and is especially indicated for cases with no medullary canal in C2 pedicles and traumatic C2–3 disk herniation compressing the spinal cord. Received for publication January 15, 2014; accepted June 10, 2014. From the *Department of Spinal Surgery, Honghui Hospital, Xi’an Jiaotong University Health Science Center; and wDepartment of Statistics and Epidemiology, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, People’s Republic of China. The authors declare no conflict of interest. Reprints: Dingjun Hao, MD, Department of Spinal Surgery, Honghui Hospital, Xi’an Jiaotong University Health Science Center, No.555 Youyi East Road, Xi’an, 710054, Shaanxi, People’s Republic of China (e-mail: [email protected]). Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved.
J Spinal Disord Tech
Volume 28, Number 2, March 2015
angman’s fracture, also known as traumatic spondylolisthesis of the axis, is defined as a fracture of bilateral C2 pars interarticularis, with a variable degree of displacement and angulation of C2 on the C3 vertebra.1 It is the second most common fracture of the C2 vertebra and accounts for 4%–7% of all cervical spine fractures2 and 23%–27% of axis fractures.3 According to the classification of Levine-Edwards,4 type II, IIa, and III hangman’s fractures are unstable as they usually have ruptures of the C2/3 disk as well as of the anterior and posterior longitudinal ligament. Nonoperative treatment of these injuries is associated with a significant rate of stabilization failure, delayed union, or residual neck pain.5–7 Surgical intervention as a primary management avoids risks inherent in conservative management and reduces the risk of catastrophic results at the fracture site and, therefore, is usually preferable in the treatment of unstable hangman’s fracture.8 Currently available surgical options include anterior cervical discectomy and fusion (ACDF) at C2–3, posterior C2 transpedicle screws, posterior fixation and fusion (PFF), and C1–3 lateral mass screws.9–12 Although C2 transpedicle screws directly address the detached posterior arch and preserve C2 motion, they fail to tackle segmental instability of C2–3.10 C1–3 fixation and fusion eliminates atlantoaxial motor function, which accounts for more than half of cervical spine motion13 and is considered overtreatment. ACDF and PFF are often applied to these fractures, with satisfactory outcomes.10,12 However, it remains unknown whether ACDF is superior to PFF or vice versa as there is no comparative study on the noninferiority of the 2 different surgical approaches. In the present study, we retrospectively reviewed the surgical records of patients with hangman’s fracture who had undergone ACDF or PFF at our institution and compared the efficacy and safety of these 2 fixation techniques.
METHODS Patients We reviewed the surgical records of 44 patients with hangman’s fracture who were admitted to our tertiary www.jspinaldisorders.com |
E61
Ge et al
care hospital between January 2006 and May 2011. Hangman’s fracture was classified according to the Levine-Edwards classification system.4 Follow-up was completed for 38 patients: 24 cases in the ACDF and 14 cases in the PFF. The study protocol was approved by the local institutional review board at the authors’ affiliated institution. The present study was conducted in accordance with the Declaration of Helsinki and with approval from the Ethics Committee of the Hong Hui Hospital. All persons gave their informed consent before their inclusion in the study.
Surgical Techniques All operations were performed by 2 similarly experienced surgeons with >20 years of experience in spine surgery and operations were performed at a single hospital. In our study, 5 cases with traumatic C2–3 disk herniation compressing the spinal cord and 2 cases of no medullary canal in C2 pedicles, confirmed by preoperative CT and MRI, were undergoing ACDF, whereas surgical procedures for the rest of patients depended on involved surgeons’ policies, not the class of fracture. Routine preoperative skull traction was performed in all patients. A weight of 2–4 kg at an appropriate angle was applied to stabilize and reduce fracture. All patients received general anesthesia by endotracheal intubation. For patients who received ACDF, the surgical procedure was performed as described by Tuite et al.14 The patient was placed in the supine position with neck slightly extended. A standard anterior horizontal incision was made midway between angle of the jaw and the thyroid cartilage. Discectomy was performed routinely, and the posterior longitudinal ligament was removed to achieve thorough decompression. Fusion of C2–3 was performed by placing a PEEK cage filled with bone substitute, supplemented with an anterior self-locking plate. For patients who underwent PFF, the operative procedure was similar to Ma et al’s procedure.10 The patient was placed in prone position, with head resting in a clamp. The upper cervical spine was routinely exposed. The entry point for C2 pedicle screws was the superior and medial quadrant of the isthmus of C2, with the insertion angle about 20 degrees medial and 25 degrees superior. The entry point of C3 lateral mass screw was the center of the C3 articular mass, with the insertion angle 20 degrees outward in the transverse plane. The cortex was penetrated at the insertion point by a high-speed spherical burr, and screws were then inserted smoothly. Suitable rods were selected, bent, and then connected to the screws with locking caps. The cartilage surfaces of the C2–3 articular process were decorticated, and bone substitute was placed in these areas. The wound was closed in standard manner under suction drainage in all patients. Postoperative immobilization was achieved with a hard collar for 3 months.
Patient Evaluation The operation time, blood loss, surgical complications, and postoperative drainage were recorded for all
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patients. The neurological functioning of patients was evaluated using the ASIA scale.15 Standard anteroposterior and lateral radiographs of the cervical spine were obtained and computed tomography (CT) with bone window of the entire cervical spine and sagittal reconstruction were also undertaken preoperatively. In addition, preoperative cervical spine magnetic resonance imaging (MRI) was performed. X-ray, CT, and MRI were also performed on the third postoperative day, at 3 and 6 months postoperatively, and then every 6 months thereafter to assess the improvement of neurological function, cervical spine motion, and the rate of fracture heeling and bone fusion. The VAS score of patients in the 2 groups were analyzed preoperatively and 3 months after surgery. The primary endpoints of this analysis were anatomic reduction rate and changes in ASIA grade.
Statistical Analysis Statistical analysis was performed using SPSS 18.0 (SPSS Inc., Chicago, IL). Two-sample t test for independent samples was used to analyze differences in operation time, blood loss, and postoperative drainage between the 2 groups. A P-value 0.05).
Surgical Outcomes The operation was successful in all 38 cases. No intraoperative or postoperative spinal cord or vertebral artery injury was observed. The mean operative time was 87 ± 8 (range, 75–110) minutes for the ACDF group, Copyright
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J Spinal Disord Tech
Volume 28, Number 2, March 2015
TABLE 1. Demographic and Baseline Characteristics of Patients Receiving ACDF or PFF in the Study All
ACDF
PFF
N (%) 38 (100) 24 (63.2) 14 (36.8) Age (y) Mean (SD) 38.1 (8.6) 36.5 (7.8) 39.6 (8.1) Range 19–65 19–52 22–65 Sex [n (%)] Male 25 (65.8) 16 (66.7) 9 (64.3) Mechanisms of injury (%) Vehicle accidents 28 (73.7) 18 (75) 10 (71.4) Falls 7 (18.4) 4 (16.7) 3 (21.4) Hits 3 (7.9) 2 (8.3) 1 (7.1) Levine-Edwards classification [n (%)] II 21 (55.3) 13 (54.2) 8 (57.1) IIa 15 (39.5) 9 (37.5) 6 (42.9) III 2 (5.3) 2 (8.3) 0 (0) Combined injury [n (%)] Head injury 16 (39.5) 9 (37.5) 6 (42.9) Facial soft tissue injury 13 (34.2) 7 (29.2) 6 (42.9) Thoraco-lumbar spine fracture 6 (15.8) 4 (16.7) 2 (14.3) Lower cervical spine fracture 5 (13.2) 4 (16.7) 1 (7.1) Fracture of extremities 5 (13.2) 3 (12.5) 2 (14.3) Left clavicle fracture 2 (5.3) 2 (8.3) 0 (0) Fracture of the mandible 2 (5.3) 1 (4.2) 1 (7.1) Neurologic deficits (ASIA) [n (%)] C 2 (5.3) 1 (4.2) 1 (7.1) D 6 (15.8) 5 (20.8) 1 (7.1) VAS Mean (SD) 5.6 (2.8) 5.3 (1.8) 5.8 (2.1) ACDF indicates anterior cervical discectomy and fusion; PFF, posterior fixation and fusion; VAS, visual analogue scale.
which was markedly shorter than that of the PFF group (mean, 149 ± 14 min; range, 120–165 min) (P < 0.01). The mean estimated blood loss was 111 ± 22 (range, 90–130) mL for the ACDF group, which was significantly less than that of the PFF group (mean, 198 ± 15 mL; range, 160–210 mL) (P < 0.01). The mean postoperative drainage was 26 ± 9 (range, 20–45) mL for the ACDF group, which was markedly lower than that of the PFF group (mean, 66 ± 7 mL; range, 55–80 mL) (P < 0.01) (Table 2). No surgical complication was reported in the ACDF group. Excessive bleeding due to injury to the venous plexus occurred in 3 cases during surgery in the PFF group, which were treated with gelatin sponge compression without development of late sequelae.
Primary and Secondary Outcomes The patients were followed up for a mean duration of 42 (range, 24–60) months. The VAS score postoperatively in the ACDF and PFF group was 1.8 ± 0.9 and 1.6 ± 0.8, respectively, which was significantly lower than their respective preoperative VAS scores (P < 0.01), but there was no difference between the 2 groups (P > 0.05). Lateral x-ray image demonstrated that solid fusion was achieved with no implant failure in all cases at the 6-month follow-up visit (Figs. 1B, 2A). At the final follow-up, 8 cases with ASIA C or D grade improved to ASIA E. No patient complained of limited mobility of cervical spine in flexion, extension, and rotation. Copyright
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ACDF for Unstable Hangman’s Fracture
TABLE 2. Comparison of Operative Variables Between the ACDF and PFF Group Variables
ACDF (n = 24)
Operation time (min) Mean (SD) 87 (8) Range 75–110 Estimated blood loss (mL) Mean (SD) 111 (22) Range 90–130 Postoperative drainage (mL) Mean (SD) 26 (9) Range 20–45
PFF (n = 14)
t
P
149 (14) 120–165
17.712
< 0.01
198 (15) 160–210
13.344
< 0.01
66 (7) 55–80
14.571
< 0.01
ACDF indicates anterior cervical discectomy and fusion; PFF, posterior fixation and fusion; VAS, visual analogue scale.
DISCUSSION Unstable hangman’s fracture has a high number of concomitant injuries and is labile to neurological compromise and development of significant complications associated with nonoperative treatment.16,17 Surgical stabilization is recommended in Levine-Edwards type IIa and type III fractures with significant dislocation.8 Our study demonstrates that both ACDF and PFF are effective for solid bony fusion and improve patient symptoms. Meanwhile, ACDF is a less invasive and simpler procedure with a shorter operative time. The estimated blood loss and postoperative drainage are also lower. Neurologic deterioration of unstable hangman’s fracture rarely occurs because of the decompressive nature of the injury itself and the ample space available for the cord in the upper cervical spine.18 The rate of spinal cord injury in our study was 21.1% (8/38), which is higher than the previously reported rate of 6% to 10%.16,19 Ruptures of the C2–3 disk, the anterior and posterior longitudinal ligament, were confirmed during execution of the anterior procedure. Hangman’s fracture usually occurs through the superior facet joint, in an area of wellvascularized spongy cancellous bone.20 The posterior approach needs to dissect the posterior cervical muscles. Furthermore, excessive bleeding due to injury to the venous plexus occurred in 3 cases in the PFF group. All these reasons may explain why the posterior approach has a longer operative time and greater estimated blood loss and postoperative drainage. As Roy-Camille et al21 first described C2–3 posterior screw-plate fixation by connecting screws inserted into fractured C2 pedicle with C3 lateral masse, PFF of C2–3 has become increasingly popular.10,22 The advantage of this procedure is direct fixation of the pars interarticularis fracture of C2 with a simple process for exposure.10 However, visible injuries to the anterior ligament and disk are neglected with a potential risk of instability.23 Moreover, the highly variable anatomy of the upper cervical spine and the presence of surrounding neurovascular structures, such as the spinal cord, nerve roots, and vertebral artery, make posterior screw fixation technically challenging, especially the insertion of C2 pedicle screws. The accuracy of C2 pedicle screws www.jspinaldisorders.com |
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FIGURE 1. A 33-year old man sustained a type II hangman’s fracture in a vehicle accident. A, Preoperative lateral x-ray image showing a apparent displacement of C2 on C3. B, Postoperative lateral x-ray image showing C2–3 fusion with a PEEK cage filled with bone substitute and anterior plate fixation.
placement cannot be guaranteed yet, even under intraoperative 3-dimensional fluoroscopy-based navigation.22 In our study, postoperative axial CT scan indicated that 5 C2 pedicle screws minimally invaded the spinal canal (Fig. 2B). The rate of misplaced screws of C2 pedicle was 17.9% (5/28), which correlates well with the published data (16.9%–21.6%).24,25 The occurrence of neurovascular injuries is very common in the posterior approach.10,22,26 As this is a high-risk procedure, many surgeons prefer the anterior approach. In our study, preoperative CT scan showed that 2 cases had no
medullary canal in C2 pedicles and chose the anterior surgery (Fig. 3). The lack of the medullary canal in C2 pedicles and too small and deformed C2 pedicle render screw placement difficult and are contraindicated for PFF. Liu et al27 believed that PFF for a highly unstable hangman’s fracture may aggravate forward displacement of C2 because of the intraoperative prone position and the forward thrust of the C2 screw, particularly with the extremely unstable state of C2. This aggravation causes iatrogenic injury and may lead to extremely negative consequences.
FIGURE 2. A 42-year-old man sustained a type II hangman’s fracture in a fall. A, Postoperative lateral x-ray image showing C2–3 fusion with C2 pedicle screws and C3 lateral mass screws. B, Axial scan of C2 showing a unilateral isthmus fracture associated with the fracture of the body of C2 and the right side of C2 pedicle screw slightly invades the spinal canal.
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J Spinal Disord Tech
Volume 28, Number 2, March 2015
ACDF for Unstable Hangman’s Fracture
approach offers patients reliable primary stability, anatomic reduction with reconstruction of cervical spine, favorable clinical outcome, and avoidance of secondary salvage fusion after failure of primary conservative treatment.29 Good clinical outcomes and no surgical complications in the ACDF group certify that the anterior procedure is a relatively effective and safe surgical procedure to manage the unstable hangman’s fracture.
CONCLUSIONS In conclusion, both the anterior and posterior approach are effective for unstable hangman’s fracture with solid bony fusion, satisfactory improvement of neck pain, neurologic status, and cervical spine motion. The anterior procedure seems to be superior as it is a less invasive and simpler procedure with fewer complications and is especially indicated for cases with no medullary canal in C2 pedicles and traumatic C2–3 disk herniation compressing the spinal cord. However, the current study is limited by its retrospective nature and small number of patients. The conclusion of the study requires further confirmation by prospective studies involving more cases. REFERENCES
FIGURE 3. Preoperative axial scan of C2 showing that there is no medullary canal in the right side of C2 pedicle.
The anterior cervical plate technique, first proposed in the 1980s, has the advantage of excising the scathing disk-ligament complex, which has a potential risk of instability.23 It is also directly decompressive for the spinal cord by removal of the disk tissue in the spinal canal. In our study, 5 cases with traumatic C2–3 disk herniation compressing the spinal cord were treated with ACDF successfully and they all showed an apparent improvement of neurological function postoperatively. Tuite et al14 reported that a patient whose fracture was not reducible by closed techniques was found to have a large epidural hematoma. After the epidural hematoma was evacuated by draining through a tear in the posterior longitudinal ligament through the anterior procedure, spinal alignment was easily obtained. Some contraindications of PFF, such as lack of the medullary canal in C2 pedicles, too small and deformed C2 pedicle, are indications for the anterior operation. Moreover, the supine position and the procedure of placement of anterior plate and screws facilitate reduction of anterior displacement of C2 body. However, the anterior approach has disadvantages as well. The high anterior approach exposes important anatomic structures at risk, especially the facial and hypoglossal nerves, branches of the external carotid, the contents of the carotid sheath, and the superior laryngeal nerve.28 However, in skilled hands, the anterior Copyright
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1. Effendi B, Roy D, Cornish B, et al. Fractures of the ring of the axis. A classification based on the analysis of 131 cases. J Bone Joint Surg Br. 1981;63-B:319–327. 2. Gehweiler JJ, Clark WM, Schaaf RE, et al. Cervical spine trauma: the common combined conditions. Radiology. 1979;130:77–86. 3. Greene KA, Dickman CA, Marciano FF, et al. Acute axis fractures. Analysis of management and outcome in 340 consecutive cases. Spine (Phila Pa 1976). 1997;22:1843–1852. 4. Levine AM, Edwards CC. The management of traumatic spondylolisthesis of the axis. J Bone Joint Surg Am. 1985;67:217–226. 5. Shin JJ, Kim SH, Cho YE, et al. Primary surgical management by reduction and fixation of unstable hangman’s fractures with discoligamentous instability or combined fractures. J Neurosurg Spine. 2013;19:569–575. 6. Vaccaro AR, Madigan L, Bauerle WB, et al. Early halo immobilization of displaced traumatic spondylolisthesis of the axis. Spine (Phila Pa 1976). 2002;27:2229–2233. 7. Watanabe M, Nomura T, Toh E, et al. Residual neck pain after traumatic spondylolisthesis of the axis. J Spinal Disord Tech. 2005; 18:148–151. 8. Li X, Dai L, Lu H, et al. A systematic review of the management of hangman’s fractures. Eur Spine J. 2006;15:257–269. 9. ElMiligui Y, Koptan W, Emran I. Transpedicular screw fixation for type II Hangman’s fracture: a motion preserving procedure. Eur Spine J. 2010;19:1299–1305. 10. Ma W, Xu R, Liu J, et al. Posterior short-segment fixation and fusion in unstable Hangman’s fractures. Spine (Phila Pa 1976). 2011;36:529–533. 11. Muthukumar N. C1-C3 lateral mass fusion for type IIa and type III Hangman’s fracture. J Craniovertebr Junction Spine. 2012;3:62–66. 12. Ying Z, Wen Y, Xinwei W, et al. Anterior cervical discectomy and fusion for unstable traumatic spondylolisthesis of the axis. Spine (Phila Pa 1976). 2008;33:255–258. 13. Dickman CA, Sonntag VK. Surgical management of atlantoaxial nonunions. J Neurosurg. 1995;83:248–253. 14. Tuite GF, Papadopoulos SM, Sonntag VK. Caspar plate fixation for the treatment of complex hangman’s fractures. Neurosurgery. 1992;30:761–764; discussion 764-5. 15. El MW, Tsubo M, Katoh S, et al. Validation of the American Spinal Injury Association (ASIA) motor score and the National Acute Spinal Cord Injury Study (NASCIS) motor score. Spine (Phila Pa 1976). 1996;21:614–619.
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16. Muller EJ, Wick M, Muhr G. Traumatic spondylolisthesis of the axis: treatment rationale based on the stability of the different fracture types. Eur Spine J. 2000;9:123–128. 17. Francis WR, Fielding JW, Hawkins RJ, et al. Traumatic spondylolisthesis of the axis. J Bone Joint Surg Br. 1981;63-B:313–318. 18. Seljeskog EL, Chou SN. Spectrum of the hangman’s fracture. J Neurosurg. 1976;45:3–8. 19. Buchowski JM, Riley LR. Epidural hematoma after immobilization of a “hangman’s” fracture: case report and review of the literature. Spine J. 2005;5:332–335. 20. Sherk HH, Howard T. Clinical and pathologic correlations in traumatic spondylolisthesis of the axis. Clin Orthop Relat Res. 1983;174:122–126. 21. Roy-Camille R, Saillant G, Mazel C. Internal fixation of the unstable cervical spine by a posterior osteosynthesis with plates and screws. Cervical Spine. 1989;25:390–403. 22. Tian W, Weng C, Liu B, et al. Posterior fixation and fusion of unstable Hangman’s fracture by using intraoperative three-dimensional fluoroscopy-based navigation. Eur Spine J. 2012;21:863–871. 23. Wang C, Ma H, Yuan W, et al. Anterior C3 corpectomy and fusion for complex Hangman’s fractures. Int Orthop. 2013;37:89–93.
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24. Yukawa Y, Kato F, Ito K, et al. Placement and complications of cervical pedicle screws in 144 cervical trauma patients using pedicle axis view techniques by fluoroscope. Eur Spine J. 2009;18:1293–1299. 25. Mueller CA, Roesseler L, Podlogar M, et al. Accuracy and complications of transpedicular C2 screw placement without the use of spinal navigation. Eur Spine J. 2010;19:809–814. 26. Ludwig SC, Kramer DL, Balderston RA, et al. Placement of pedicle screws in the human cadaveric cervical spine: comparative accuracy of three techniques. Spine (Phila Pa 1976). 2000;25: 1655–1667. 27. Liu J, Li Y, Wu Y. One-stage posterior C2 and C3 pedicle screw fixation or combined anterior C2-C3 fusion for the treatment of unstable hangman’s fracture. Exp Ther Med. 2013;5:667–672. 28. McAfee PC, Bohlman HH, Riley LJ, et al. The anterior retropharyngeal approach to the upper part of the cervical spine. J Bone Joint Surg Am. 1987;69:1371–1383. 29. Junge A, El-Sheik M, Celik I, et al. Pathomorphology, diagnosis and treatment of “hangman’s fractures”. Unfallchirurg. 2002;105: 775–782.
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