Treatment of Remote Type II Axis Fractures in the Elderly: Feasibility of Anterior Odontoid Screw Fixation
Agrillo, Antonino M.D.; Russo, Natale M.D.; Marotta, Nicola M.D.; Delfini, Roberto M.D.
Department of Neurological Sciences–Neurosurgery, Umberto I Hospital, University of Rome La Sapienza, Rome, Italy
Reprint requests: Natale Russo, M.D., Umberto I Hospital, Viale del Policlinico 155, 00100 Rome, Italy. Email: firstname.lastname@example.org
Received, February 19, 2008.
Accepted, August 15, 2008.
OBJECTIVE: This preliminary study considers the feasibility and the results of anterior screw fixation in elderly patients with remote Type II axis fractures. Odontoid fractures are the most common fractures of the cervical spine in people 70 years of age or older. In developing countries, direct anterior fracture fixation is replacing posterior fusion in many cases. Recently, it has been demonstrated that patient age does not influence the outcome in terms of fusion after odontoid screw fixation. There is considerable disagreement about correct treatment in the case of remote fractures. In the literature, there have been no studies considering the feasibility and results of anterior screw fixation in elderly patients with remote Type II axis fractures.
METHODS: From 1989 to 2005, we observed 9 patients over the age of 65 years with isolated Type II remote fractures of the dens. All fractures were considered to be inveterate, as the traumatic events had occurred 6 to 12 months earlier. All fractures were treated with anterior infibulation of the dens with single 3.5-mm cannulated screws.
RESULTS: A bony fusion was radiologically documented in 7 patients (77%) 4 to 16 months after the intervention. In 1 patient, a fibrous union was observed. The neurological status remained unchanged in all patients, and no patients showed any neurological impairment at the time of follow-up.
CONCLUSION: According to our preliminary study, the technique appears to be feasible for remote axis fractures within 12 months of trauma, and it seems to be safe for elderly patients. Further data from additional studies are needed.
ABBREVIATION: CT, computed tomographic
More than 60% of all spinal injuries involve the cervical spine, and as many as 15% of all cervical fractures involve the odontoid process (8). Odontoid fractures become more frequent with advancing age and are the most common fractures of the cervical spine in people aged 70 years or older and the most frequent of all spinal fractures in those aged 80 years or older (34,41). How odontoid fractures should be managed, and especially how Type II odontoid fractures should be treated in elderly patients, remains debatable (3,24). External immobilization with a hard collar is a widely used option that abolishes the need for surgical intervention but increases the risk of nonunion, especially in the elderly (12,25,41). Another disadvantage is that many elderly patients cannot tolerate immobilization in a halo vest, and these rigid cervical orthoses may give rise to numerous complications (17,35,44). Although posterior fusion has a lower risk of nonfusion than use of the halo vest, it has the functional limitation of reducing the rotational range of movement in the neck by up to 40%, and it decreases flexion-extension by 10% (22,45). Conversely, anterior odontoid fusion using a screw provides immediate rigid internal fixation, achieves a high fusion rate, and preserves the range of movement in the cervical spine (36,39). In developing countries, as surgical techniques advance, posterior fusion has in many cases given way to direct anterior fracture fixation (37).
Before the decision is made to perform an anterior spinal screw fixation operation, care must be taken to exclude patients in whom this type of surgery is contraindicated (20,21). The major recognized anatomic contraindications include a comminuted fracture at the base of the dens, a disrupted transverse ligament, and, in many cases, a fracture line oriented in a cranial posterior-to-caudal-anterior direction (5,10). A recent study concluded that age has no influence on fusion rates after odontoid screw fixation and suggested that, in selected cases, even elderly patients with odontoid axis fractures can safely undergo early surgical intervention with anterior dens screw fixation (6,7,26). Nonetheless, treatment for patients with a remote history of injury who present for delayed treatment of odontoid fractures remains controversial (6,7,25,26,40), because remote (nonrecent) odontoid fractures are often discovered incidentally, and the literature offers few reported series. We designed this preliminary retrospective study to investigate the feasibility of delayed surgical single-screw anterior fixation for Type II odontoid axis fractures in elderly patients presenting 6 to 12 months after the trauma.
PATIENTS AND METHODS
We retrospectively reviewed the clinical records of all patients older than 65 years of age who were admitted to our university's neurosurgical department from January 1989 to December 2005 with a diagnosis of C2 fractures treated with external immobilization or internal reduction and surgical fusion. From these 114 consecutive patients, we selected 9 patients with isolated Anderson and D'Alonzo Type II odontoid fractures who underwent delayed anterior single-screw fixation at least 6 months after the trauma for study (Table 1) (2). We excluded 2 patients, 1 of whom underwent dens fixation 1 month after the trauma and another who underwent posterior screw fixation for a comminuted fracture 2 months after the trauma. All of the other 103 patients were treated in the acute phase.
None of the patients selected for study had major contraindications to anterior odontoid screw fixation, such as a barrel chest or a short neck; morphological fracture contraindications such as comminuted fracture, fracture associated with fixed listhesis, ruptured transverse ligaments, or substantial nonreducible fragment angulation or dislocation; or contraindications resulting from concomitant clinical conditions or medical history, such as myelopathy resistant to transcranial traction, severe osteoporosis, rheumatoid arthritis or other inflammatory diseases, or craniocervical junction malformations or tumors. One patient who had a fracture rime directed caudally and forward was included because the fracture seemed correctly reduced after traction.
In 3 patients, the fracture was misdiagnosed at the time of the traumatic event. Three patients reported having sustained a minor trauma some months earlier, but they had not gone to the emergency department. In 2 patients, the old fracture was an incidental radiological finding while the patient was undergoing a radiological examination for another reason. One patient was unable to tolerate conservative treatment with cervical immobilization using the halo vest, and the sternal-occipital-mandibular immobilizer brace also failed.
Three patients were asymptomatic. Four patients presented with neck pain and stiffness without neurological symptoms. Three of these 4 patients exhibited a mild limitation of cervical range of movement. One patient arrived at the emergency department with a 2-day history of worsening arm and leg paresthesia. One patient reported transient episodes of arm and leg paresthesia but, when seen by us, was asymptomatic.
All fractures were documented with conventional anterior, open-mouth, and lateral x-rays and computed tomographic (CT) scans. In 2 patients, CT studies included a dynamic flexion-extension scan with reconstructions. The 5 patients in whom CT scans or x-ray studies disclosed a suspected disruption of the transverse atlantal ligament underwent magnetic resonance imaging scans to assess the integrity of the ligament. Dislocation of the dens body was calculated from standard lateral x-rays and cervical sagittal CT reconstructions. The transverse diameter of the dens was evaluated on the standard axial CT scan or on its sagittal reconstructions. The anesthesiological risk was determined according to the guidelines of the American Society of Anesthesiologists (1). A manual closed reduction of the fracture or a halo traction system was used to favor dens realignment if required and was verified preoperatively with standard lateral x-rays.
All fractures were treated with anterior infibulation of the dens using a single cannulated screw, as described elsewhere (4). The cervical spine was exposed through an anterior precarotid approach. After cervical exposure, a K-wire was positioned on the inferior edge of the C2 vertebra, and a hole was drilled and tapped through the odontoid process to its tip. Whenever necessary to facilitate this maneuver, minimal drilling of a small portion of the upper body of C3 was achieved. In no case was the fracture refreshed with a curette. A single cannulated 3.5-mm odontoid screw with a nonthreaded proximal shaft was inserted under biplanar fluoroscopic guidance. Whenever feasible, to maximize lag compression, the screw threads engaged the cortical tip of the dens.
Six months after anterior fixation, 1 patient underwent posterior C1–C2 fixation with sublaminar clamps and a bone graft, whereas another patient declined this option. In all patients, a plastic Philadelphia collar was applied after the operation. All patients underwent serial radiological examinations to verify postoperative alignment and fusion. Fusion was defined as continuity of the cortical bone, as documented on conventional anterior and lateral x-rays and a sagittal CT scan. Fibrous union was considered present when radiographic images showed no evidence of cortical bone restoration and persistent appreciable cortical bone discontinuity despite granular tissue within the fracture site. Nonunion was defined as no visible tissue at the fracture site. Direct late contacts with the patients were used to obtain the clinical follow-up and neurological outcome (mean time, 18 months).
The series of 9 patients comprised 6 men and 3 women whose ages ranged from 67 to 84 years (mean age, 73 years) (Table 1). Of the 9 odontoid fractures treated, 5 had a horizontal orientation, 3 had a posterior oblique orientation, and 1 had an anterior oblique orientation, according to the proposed fracture orientation criteria (5). In 7 patients, preoperative imaging, including standard lateral x-ray films and cervical sagittal CT reconstructions (Fig. 1), showed that the fractured odontoid fragments were displaced posteriorly to anteriorly (from −1.5 mm to +6 mm). Fragment angulation ranged from −12 degrees to +35 degrees. One patient also had a 4-mm fragment diastasis (Fig. 2). The dens ranged from 10 to 14 mm in diameter. No patient was in an American Society of Anesthesiologists risk class higher than II (1). In 3 patients, the dens was preoperatively realigned with a halo traction system with weights ranging from 7 to 10 lbs (3–4.5 kg), whereas in 2 patients, manual reduction sufficed. In all patients, successful screw positioning was verified by postoperative radiographic images. Apart from transient dysphagia in 2 patients, none of the fixation procedures led to postoperative complications. All patients were discharged from the hospital within 4 days of the operation.
In 7 (77%) of the 9 patients, radiographic follow-up assessments documented bone fusion within 4 to 16 months after the intervention. In the patient who had an anterior oblique fracture, although the screw was well positioned, postoperative x-rays and CT scans disclosed a residual atlantoaxial dislocation (Fig. 3). The patient declined to undergo posterior open reduction and fixation. Nevertheless, follow-up at 16 months showed bone fusion (Fig. 4). In the patient whose fractured fragments showed diastasis (Fig. 2), follow-up scans at 6 months (Fig. 5) documented no bone fusion, even though the screw appeared to be correctly placed and engaged the tip of the dens. This patient underwent posterior C1–C2 fusion with sublaminar clamps and bone graft. In 1 patient, CT scans showed fibrous union (Fig. 6), but on dynamic x-ray images, the fracture appeared stable. All patients underwent late clinical follow-up assessment for an average of 18 months. No patient manifested neurological impairment at the time of follow-up, whereas 2 patients reported experiencing residual cervicalgia.
Treatment of Type II axis fractures is controversial, and different conservative and surgical options exist. Important features that influence bony fusion in odontoid fractures treated with all external immobilization devices are a delayed presentation, a dislocation of the fragment of more than 6 mm, age older than 65 years, and the comminution of the base of the dens (Hadley IIa) (11,19,21,23,30). Hanigan et al. (25) documented a fusion rate of 50% in a series of patients age 80 years or older with odontoid Type II axis fractures that were treated conservatively. Lennarson et al. (33) concluded that patients over the age of 50 years had a 21 times greater chance of nonunion of acute odontoid fractures treated with immobilization than with surgery. Moreover, the use of halo devices has even been related to complications such as pin loosening, pin site infections, cerebrospinal fluid leakage from the pinhole, and brain abscess (14,16–18,28).
Recently, in the literature, attention has been paid to the complications of the halo vest in elderly patients, and it has been emphasized that the device is not well tolerated by all patients. Patients older than age 65 years who are treated with a halo device have a high risk for the development of pneumonia and acute cardiac or respiratory failure (35,40,44). Various investigators have suggested posterior fusion for elderly patients (3,31). Pepin et al. (40) suggested a posterior C1–C2 fusion for patients older than 75 years of age because of their intolerance of the halo vest. Conversely, other authors have proposed an anterior approach with screw fixation even for the elderly population (6,7,26).
Anterior screw fixation provides the most anatomic and functional result for odontoid fractures (32). Our fusion rate in elderly patients compares well with reported anterior screw odontoid fixation rates, ranging from 75 to 96% in patients of all ages who have undergone early fixation (15,43). The good rate we achieved in elderly patients is in line with the study by Börm et al. (7), who reported solid bony fusion in 75% of patients older than 70 years whose odontoid fractures were treated with early anterior screw fixation; they concluded that outcome is not influenced by age. In elderly patients who present with minimal symptoms or are asymptomatic, this surgical technique offers acceptable fracture healing and an uncomplicated postoperative course. Only 1 patient in our series presented with myelopathy, which responded to halo traction. In contrast to our study, Kirankumar et al. (29) reported that several patients in their series with Anderson Type II fractures presented with late compressive myelopathy and underwent anterior decompression.
Another important factor that almost certainly influences fusion rates and hence the decision on which management option to choose is the time elapsing after the trauma. Because all the patients whose records we reviewed presented for delayed treatment of odontoid fractures more than 6 to 12 months after the causative traumatic event, we cannot compare their outcomes with those of patients in other reported series, such as that of Apfelbaum et al. (5), whose patients underwent early treatment or delayed treatment more than 18 months after trauma. In their series, anterior screw fixation in 18 patients with axis fractures treated more than 18 months after injury resulted in a nonfusion rate of 31% (5). Stressing this poor result, they suggested anterior screw fixation for patients with fractures within 6 months after trauma and posterior C1–C2 fusion for fractures discovered more than 18 months after injury (5). In 80% of their patients, the authors inserted 2 screws (5). A technical point is the use of a single screw or 2 screws for odontoid fixation procedures. Especially in long-standing fractures, whose fracture edges tend to become sclerotic on the side of the fracture line, we suppose that a single screw probably ensures a larger surface for fusion between fragments. Two screws do not necessarily ensure a higher rate of fusion (27,42). In a series of 42 patients (20 treated with the 1-screw and 22 with the 2-screw procedure), Jenkins et al. (27) reported similar bone fusion rates in the 2 groups (81 versus 85%). Because their series included patients with recent odontoid fractures, whether a single screw ensures a higher rate of bone fusion in patients undergoing late treatment remains open to question.
In contrast to other series, none of our patients presented with fixed atlantoaxial anterolisthesis or retrolisthesis, and preoperative traction alignment under radiological control was successful in all patients in whom we used it (9). Even in the patient whose fracture had a slight anterior oblique rime and a large displacement (Fig. 7), we realigned the dens with halo traction. Although the patient's neurological status improved during the postoperative course, the postoperative radiographic studies showed residual atlantoaxial dislocation (Fig. 3). This finding prompted us to propose posterior fusion surgery, but the patient refused and was discharged wearing a Philadelphia collar. A late CT follow-up scan at 16 months showed bone union with partial bone remodeling (Fig. 4), and the patient remained free of neurological symptoms.
In 2 (22.2%) of the 9 patients in this series, anterior screw fixation failed to achieve bone fusion. In 1 patient with minor odontoid displacement, preoperative and postoperative imaging showed evident fragment diastasis (Figs. 2 and 5). In these cases, the fixation may fail because the odontoid screw leaves a gap between the fragments (Fig. 5) that may cause the C2 vertebral body to fracture during neck flexion-extension (13). We think this risk could be eliminated by using posterior C1–C2 fixation to limit neck flexion-extension. In the other patient in whom postoperative assessment showed no bone fusion, follow-up imaging at 8 months (Fig. 6) and 14 months showed fibrous union that appeared stable on dynamic CT scan reconstructions. We suggest that, in elderly patients, a fibrous union with no signs of instability, no residual listhesis, and an anatomic dens alignment should be considered a satisfactory outcome, although a definitive conclusion awaits data from further research.
The patients in this series who presented for delayed treatment of odontoid fractures were selected to undergo anterior fixation according to the currently accepted criteria. The major recognized anatomic contraindications include a comminuted fracture at the base of the dens that makes it impossible to compress the fragments and a disrupted transverse ligament (10,20). Even though a fracture line oriented in a cranial-posterior to caudal-anterior direction may lead to incorrect alignment, we used this management option in 1 patient and resorted to a nonanatomic bone fusion (Fig. 4), although the patient had a successful neurological outcome (5). Finally, some deem a transverse dens diameter of 9 mm as critical for the placement of a 3.5-mm odontoid screw (38). Although osteoporosis is generally listed among factors influencing bone fusion, precisely how osteoporosis should be graded remains unclear (26,37). No patients in our series had marked or severe radiological signs of osteoporosis on x-rays, but we did not determine the possible correlation of this feature to the time elapsing between trauma and the overall time needed for bone fusion. Another imperative preoperative task, especially in elderly patients, is that of quantifying the anesthesiological risk. This caveat notwithstanding, patients presenting for delayed nonemergency treatment of an odontoid fracture generally have no acute anesthesiological contraindications to a neurosurgical intervention.
Anterior screw fixation is an appropriate operative treatment for Anderson Type II dens fractures if patients fulfill all of the current criteria. Our preliminary data suggest that the technique appears feasible for managing remote axis fractures within 12 months after the trauma, seems safe in the elderly, and offers acceptable fracture healing.
Further studies are needed to investigate whether factors such as the orientation of the fracture line, the reducibility of the fracture, the preoperative myelopathy, the use of 1 or 2 screws, and osteoporosis influence the outcome. An anterior oblique fracture line does not necessarily contraindicate anterior screw odontoid fixation if the dens can be realigned, but nonanatomic bone fusion may occur. Lag screw compression appears fundamental in favoring bone fusion, insofar as nonfusion and instability may be related to persistent fragment diastases. Preoperative assessment must include a careful evaluation of the anesthesiological risks. A long radiological follow-up is indicated to make sure that the dens remains properly aligned and to document late ossification.
The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
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Agrillo et al. present a small but important series of elderly patients with odontoid fractures (n = 9) treated via an anterior approach. The results are similar to those of previous series demonstrating a higher nonunion rate in the elderly, and ultimately 2 of the patients did not heal successfully. Nevertheless, one can understand the appeal of odontoid screws in the elderly. Although the local preservation of atlantoaxial motion is not only suspect but also of limited clinical significance in these older patients, the reduced surgical morbidity (including the ability to perform the surgery in the supine position, reduced postoperative pain, and lower infection rates) offers distinct advantages. The authors achieved excellent results, and ultimately this strategy (using the less morbid surgery first, and revising only when absolutely necessary) may be the most successful approach in these patients, who are prone to developing complications.
Michael Y. Wang
The authors have extended our knowledge of when it is possible to treat odontoid fractures by direct odontoid screw fixation. In our experience (2), we had patients who self-sorted into 2 groups, those who underwent operations within 6 months of the injury and those whose surgery was performed after 18 months or more, which we termed remote injuries. We tried odontoid screw fixation on both groups and found that the earlier group had good results, with about 90% fusion success. This was true if we treated them within days of their injury or up to the 6-month point. Surgery for the remote injuries, however, was much less successful, leading us to recommend posterior fusion for this group. We did not have any cases, however, within the 6- to 12-month interval, so we could not make a recommendation of one form of treatment over the other for these patients. The present study fills that void and shows that, at least up to 1 year, odontoid screw fixation can be expected to be successful in the majority of cases.
This correlates with the observation that nonunited anterior cervical fusions treated with additional posterior stabilization will usually go on to fuse, even after a substantial period of time, indicating that once it has been well immobilized, the fusion can and will progress. That this will occur even in elderly patients is encouraging, as these patients will not heal well with external immobilization, as Lennarson et al. (3) have shown, and a direct odontoid screw fixation procedure is a quicker procedure and incurs less morbidity than a C1–C2 fusion in the elderly.
To clarify our technique: we do not recommend using cannulated screws over a K-wire because of the risk of advancing the wire and causing neural damage. Our technique, which the authors referenced (1,2), uses a drill guide tube system that allows realignment of the spine and the placement of the screws through this; we feel that this technique is safer. The authors, however, emphasize starting the drill hole low on C2 along its inferior surface, drilling through the apical cortex, and engaging it with the screws, both of which are important. The screw heads, however, should be drawn up tight against the inferior edge of C2 to achieve the lag effect and compression of the odontoid to the body of C2. In Figures 2 and 4 of the article, the screw heads are too far inferior, but since the apical cortex was obviously drilled, this may represent back-out of the screws rather than failure to tighten them enough.
Finally we do not agree with the authors' speculation regarding 1 screw versus 2 screws. A recent analysis of our elderly patient series shows much better success with 2 screws (95%), rather than 1 screw (56%; P = 0.01) in this elderly population (Dailey et al., unpublished data). We believe that this occurs because of better immobilization in weaker osteopenic bone and because the second screw prevents rotation of the odontoid relative to C2, which can occur if they cannot be lagged tightly together. This difference was not seen in younger patients, in whom the results for 1 and 2 screws were not statistically different.
Ronald I. Apfelbaum
Salt Lake City, Utah
1. Apfelbaum RI: Anterior screw fixation of odontoid fractures, in Rengachary SS, Wilkins RH (eds): Neurosurgical Operative Atlas. Baltimore, Williams & Wilkins, 1992, vol 2, pp 189–199.
2. Apfelbaum RI, Lonser RR, Veres R, Casey A: Direct anterior screw fixation for recent and remote odontoid fractures. J Neurosurg 93 [Suppl]:227–236, 2000.
3. Lennarson PJ, Mostafavi H, Traynelis VC, Walters BC: Management of type II dens fractures: A case-control study. Spine 25:1234–1237, 2000.
This small case series of minimally symptomatic/asymptomatic elderly patients with C2 fractures treated in a delayed fashion (at 6–12 months) demonstrates that it is possible to place C2 screws in such patients and that reasonable fusion rates may be obtained (the fusion rate is reported to be 77%, although, from the case descriptions, it seems that 3 of 9 patients failed fixation and another patient had a stable nonunion, for a fusion rate of 55%). Although this fusion rate is not outstanding, it may make delayed C2 anterior screw fixation a reasonable option for the elderly, in whom a less invasive option is particularly appealing.
Daniel K. Resnick
Type II odontoid fractures are relatively common in the elderly. The authors describe 9 patients who presented with odontoid Type II fractures 6 to 12 months after their initial injury. All patients underwent fixation with a single anterior odontoid screw. Successful osseous union was achieved in 7 of the 9 patients. One patient had a fibrous union, and 1 patient failed to achieve fusion. This outcome is somewhat surprising, especially considering the examples provided by the authors. Sclerotic bone seems to have formed at the fracture site, but solid fusion was still achieved. The authors rightly point out the increased complication rate associated with treating these fractures with a halo or collar. Consequently, I will reconsider routinely performing posterior C1–C2 fusion in elderly patients with a delayed odontoid Type II fracture and will consider whether they should instead be treated with anterior screw fixation, as these authors have done.
Volker K.H. Sonntag
Agrillo et al. report a 77% fusion rate in a small group of elderly patients with Type II odontoid fractures. The fractures varied in age from 6 to 12 months. The authors did not “freshen” the fractures, and all patients were immobilized in a collar. Although bone density data are not provided, it can be appreciated from the provided figures that these patients had fairly good bone quality. This is an important consideration when using anterior screw fixation.
Posterior C1–C2 fusion in elderly patients provides more secure fixation, which may be important if there is significant instability or if the bone quality is poor. Many of these patients have already lost some rotatory motion, and the additional degree of rotational restriction is not usually clinically significant.
Vincent C. Traynelis
Iowa City, Iowa
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Anterior screw fixation; Axis fracture; Elderly population; Odontoid fracture
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