Nonrestrictive Fixation Strategy for Upper Cervical Spine Fractures Associated With Diffuse Idiopathic Skeletal Hyperostosis: A Case Report

Abstract

Background

Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by calcification and ossification of the anterior longitudinal ligament, forming multilevel bony bridges. This pathological change leads to spinal stiffness and produces a “long lever arm effect”, making patients extremely prone to unstable upper cervical fractures even with low-energy injuries. Although traditional occipitocervical fusion or multilevel posterior fusion can provide stability, they can lead to a catastrophic loss of cervical mobility. We present a rare case of DISH in combination with Jefferson, hangman’s, and C2 to C3 osteophyte fractures, along with a therapeutic strategy focused on functional preservation.

Case Presentation

A 66-year-old man presented with cervical pain and limited mobility following a low-energy fall. Imaging confirmed the presence of a Gehweiler type III Jefferson fracture, a Levine-Edwards type IIa hangman fracture, and an associated C2 to C3 anterior osteophyte fracture, alongside characteristic features of DISH. A nonrestrictive fixation strategy was adopted to restore the stability of the fracture site while preserving part of the motor function of the upper cervical spine. C1-ring osteosynthesis was performed, and posterior long-segment internal fixation was applied to C2 to C4; the C1 construct was deliberately not linked to the subaxial construct. Postoperative assessments demonstrated adequate fracture healing, stable internal fixation, resolution of neck pain, and partial preservation of motor function in the upper cervical spine.

Conclusions

For patients with DISH and complex upper cervical fractures, total segment fusion should not be pursued without careful consideration of functional outcomes. This case highlights a novel, deliberately uncoupled, segment-specific fixation strategy (coupling independent C1 ring fixation with a targeted subaxial construct). This approach fulfills local mechanical demands for fracture healing while maximizing the preservation of partial residual upper cervical motion.

Introduction

Diffuse idiopathic skeletal hyperostosis (DISH), also known as Forestier’s disease, is a systemic noninflammatory degenerative condition that predominantly affects the spinal column in middle-aged and elderly populations.^1–3 Pathologically, the disease is defined by the gradual calcification and ossification of the anterior longitudinal ligament, culminating in the formation of multisegmental bony bridges. This substantial ossification impairs spinal flexibility and reduces energy attenuation capability, thereby significantly altering the spinal biomechanical character.⁴ In this diseased context, the stiffened spinal column produces a substantial “long lever arm effect,” resulting in pronounced stress concentration.⁴ Consequently, even minimal or low-energy trauma can lead to significantly unstable fractures.

The upper cervical spine accounts for roughly 50% of the rotation, flexion, and extension of the cervical spine.⁵ In instances of DISH associated with unstable upper cervical fractures, traditional occipitocervical fusion or posterior multisegmental fusion, although ensuring dependable stabilization, leads to a catastrophic loss of cervical range of motion.⁶

In the present article, we report a rare clinical case of DISH occurring simultaneously with Gehweiler type III injury (Jefferson fracture) and Levine-Edwards type IIa injury (hangman’s fracture) alongside an associated fracture of C2 to C3 osteophytes. In light of the stability of the fracture site and the clinical necessity to preserve postoperative upper cervical mobility, a nonrestrictive fixation strategy involving C1-ring osteosynthesis combined with posterior C2 to C4 long-segment internal fixation was executed, resulting in a positive clinical outcome.

Case Presentation

A 66-year-old man presented 10 hours after an accidental fall at home, presenting symptoms of cervical pain, limited mobility, and weakness in all 4 extremities. Physical examination indicated restricted cervical spine motion, normal muscular tone in both upper extremities, no substantial reduction in skin sensation, bilateral limb muscle strength graded IV, negative pathological reflexes, and the presence of physiological reflexes. The patient’s body temperature, serum human leukocyte antigen B27 level, and erythrocyte sedimentation rate were all within normal limits. The patient had no previous medical issues and no history of diabetes mellitus or hypertension. Cervical computed tomography (CT) and magnetic resonance imaging (MRI) identified a Jefferson fracture (type III)⁷ alongside fractures of the right anterior and posterior arches, in addition to a hangman’s fracture (type IIa)⁸ involving the axis vertebral body and a C2 to C3 osteophyte fracture (Figure 1). Moreover, distinctive features of DISH were apparent: ossification of the anterior longitudinal ligament extending across a minimum of 4 adjacent vertebral bodies, together with intervertebral joint fusion² (Figure 1c).

Figure 1.

Illustrative of cervical spine imaging at the time of admission. (A) Axial computed tomography (CT) reveals fractures at the anterior and posterior arches of the atlas (red arrows). (B) Axial CT demonstrates a fracture of the axis (red arrow). (C) Sagittal CT shows a C2/C3 osteophyte fracture (red arrow) and multiple ossifications of the anterior longitudinal ligament in the vertebral bodies (white box). (D) Sagittal magnetic resonance imaging of the cervical spine.

In order to ensure the stability of the fracture site while preserving maximum mobility, the procedure of choice was C1-ring osteosynthesis combined with posterior long-segment internal fixation of C2 to C4. During the operation, 2 lateral mass screws were implanted into the atlas through an intraoperative fluoroscope and connected with a transverse rod; 2 pedicle screws were implanted into C2, and 4 lateral mass screws were implanted into C3/C4, with titanium rods connecting each side. Internal fixation of the atlas was not connected to the internal fixation of C2 to C4. After surgery, the patient returned to the ward in stable condition. A rigid cervical orthosis was maintained for a period of 3 months postoperatively in order to minimize stress concentration and was then removed sequentially upon confirmation of solid arthrodesis via CT imaging.

Cervical x-rays performed 1 week postoperatively revealed adequate reduction of the upper cervical fractures, with the internal fixation screws positioned optimally (Figure 2). At the 3- and 7-month postoperative follow-ups, the patient had substantial alleviation of neck pain, exhibiting no apparent discomfort. The visual analog scale at 3 months and 7 months after surgery was 3 and 1, respectively. Concurrently, the Neck Disability Index was 22 (44%; indicating severe dysfunction) and 11 (22%; indicating moderate dysfunction), respectively. Cervical x-rays and CT indicated that the internal fixation was stable with no signs of loosening, fracture, or migration. The fracture line of the axis grew more obscure, similar to that of the posterior arch of the atlas. Additionally, a decrease in the distance between the fracture ends of the anterior arch was noted, along with evident osseous fusion at the location of the fractured C2 to C3 anterior osteophytes (Figure 3).

Figure 2.

Postoperative 1-wk cervical spine x-ray in both frontal and lateral views.

Figure 3.

Cervical spine imaging at 3 (A–C) and 7 (D–F) mo postoperatively. (A and D) Axial computed tomography (CT) of the atlas. (B and E) Axial CT of the axis. (C and F) Sagittal radiograph of the cervical spine.

At the 13-month postoperative follow-up, the visual analog scale and Neck Disability Index scores were 1 and 8 (16%; indicating mild dysfunction), respectively. The patient exhibited the preservation of partial cervical flexion-extension and rotation function. Dynamic flexion-extension lateral radiographs and CT scans demonstrated stable internal fixation, with no signs of loosening, fracture, or migration (Figure 4). Angular motion at C0 to C1 and C1 to C2 was approximately 20° and 13°, respectively. Bony union was observed at the fracture sites of the atlantoaxial centrum and the anterior osteophytes at C2 to C3. A visual inspection of the patient’s head revealed a left rotation of approximately 10° and a right rotation of approximately 25°, as measured using a protractor (Figure 5).

Figure 4.

Cervical spine imaging at 13 mo postoperatively. (A) Flexion cervical radiograph. (B) Extension cervical radiograph. (C) Axial computed tomography (CT) of the atlas. (D) Axial CT of the axis. (A and B) The yellow line indicates McRae’s line, the red line indicates the C1 anterior-to-posterior arch line, and the blue line indicates the C2 inferior vertebral body border line.

Figure 5.

Clinical photographs of the patient’s appearance. (A) Right head rotation. (B) Neutral head position. (C) Left head rotation.

Discussion

The diagnosis of DISH can be made through imaging studies such as radiography, CT, and MRI, with the hallmark finding being continuous bony outgrowth and bridging of the anterior edges of ≥4 adjacent vertebrae.² The existence of multisegmental anterior osseous bridging impairs the spine’s capacity to absorb stress on a vertebra-by-vertebra basis, and the stiff spine forms a massive “long lever arm,” which amplifies and transmits the flexion or extension moment to the relatively susceptible distal vertebral segments.⁴ When this “long lever arm effect” occurs in the cervical spine, even low-energy trauma can lead to unstable fractures of the upper cervical spine, with a 4 to 8 times higher risk of fracture compared with nonspinal stiffness individuals.⁹ At this juncture, in view of the presence of the “long lever arm effect” and unstable fractures, conservative treatments such as halo vest are no longer applicable, as they may significantly elevate the risk of problems such as nonunion and upper cervical instability.¹⁰ Therefore, stiff internal fixation surgery is essential to treat these fractures and restore spinal stability.

In cases of unstable fractures of the upper cervical spine, conventional surgical methodologies predominantly include occipitocervical or long-segment upper cervical fusion. These treatments can offer immediate stabilization; however, they compromise the range of motion of the upper cervical spine, significantly affecting patients’ quality of life and postoperative satisfaction.¹¹ Patients with DISH and upper cervical fractures frequently demonstrate pathological fusion of the lower cervical spine. If the upper cervical spine is surgically fused at this juncture, the patient will have a “devastating” reduction in overall cervical mobility. Consequently, the selection of a surgical procedure needs to achieve an optimal balance between ensuring the stability of the fracture site and preserving the motor function of the cervical spine.

Currently, there are no specific guidelines for the treatment of such complex cervical fractures. Surgeons usually choose the best treatment based on their experience and knowledge of certain surgical procedures. The patient had a complex medical history, characterized by DISH, Jefferson fracture (type III), hangman’s fracture (type IIa), and C2 to C3 osteophyte fracture. In view of the resulting cervical stiffness, an anterior approach was rendered challenging with regard to achieving adequate exposure of the C2 and C3 vertebral bodies. This in turn prompted consideration of a posterior surgical approach. Furthermore, the patient’s imaging data did not demonstrate any indicators of transverse atlantal ligament rupture¹²; the total displacement distance of the lateral mass of the atlas on CT was greater than 6.9 mm; the enlargement of the anterior atlanto-odontoid interval on CT was greater than 5 mm; CT showed that an avulsion fracture of the medial margin of the atlantoaxial vertebra was present; or there was direct demonstration of transverse atlantal ligament rupture on MRI. However, posterior surgery involves the dissection of soft tissues near the atlas, which has the potential to compromise the stability of the atlas in Jefferson fracture (type III). In light of the aforementioned considerations, a nonrestrictive fixation strategy was implemented, entailing the discrete management of injuries to the atlas and C2 to C3, while ensuring that the occipital-atlas-axis remained uncrossed.

Initially, the C1-ring osteosynthesis procedure was employed for Jefferson fracture (type III), incorporating lateral mass screws and transverse rods. This approach reinstates the height between the C0 and C2 vertebral bodies by recreating the annular structure of the atlas, thereby better preserving the anatomical integrity and functionality of the C0 to C1 and C1 to C2 joints.¹³ Compared with traditional posterior fixation alone, the addition of transverse rods converts isolated fixation into a 3-dimensional “C”-shaped stabilization. This design more accurately replicates the atlas’s intrinsic annular structure, thereby improving structural stability. The methodology has undergone stringent biomechanical validation and is also reinforced by the theoretical foundations of the buoy hypothesis.¹⁴ Second, due to the spinal rigidity associated with DISH and the instability of the fracture, the prevailing academic consensus indicates that this type of fracture generally requires fixation of at least 3 segments above and below the fracture site.¹⁵ Thus, for instances of hangman’s fracture (type IIa) and C2 to C3 osteophyte fracture, we utilized a posterior internal fixing technique extending from C2 to C4. It is important to emphasize that the patient was required to continue wearing a rigid cervical orthosis for a period of 3 months following the operation. The device has been shown to limit cervical movement, improve fusion rates, and provide additional spinal stability.¹⁶

To date, there have been no previous reports documenting an identical deliberately uncoupled, noncontiguous upper cervical construct specifically for complex atlantoaxial fractures within a DISH matrix. This underscores the distinct clinical novelty of our strategy. Nevertheless, the concept of personalized, segmental surgery—such as the nonrestrictive fixation strategy described in this article—has been established in complex spinal surgery. For instance, Ushijima et al reported a case of a patient with DISH who presented with simultaneous, noncontiguous fractures at both the cervicothoracic and thoracolumbar junctions, which were fixed separately.¹⁷ Similarly, concurrent upper and subaxial fractures in multilevel cervical trauma have been shown to result in favorable clinical and radiological outcomes when each injured segment is subject to separate regional fixation during medium- to long-term follow-up.¹⁸ Furthermore, within the domain of multilevel cervical degenerative disorders, hybrid surgery—which strategically integrates cervical disc arthroplasty with separate anterior cervical discectomy and fusion blocks—offers a tailored approach.¹⁹

The cornerstone of this nonrestrictive fixation strategy lies in the deliberate uncoupling of the C1 ring osteosynthesis from the subaxial fixation framework, representing a specialized surgical philosophy rather than a mere contiguous compounding of 2 established techniques. The C1-ring osteosynthesis procedure recreates the annular structure of the atlas. Under the orthotic support of a postoperative rigid collar, the cranial mass is transmitted predominantly as axial compressive loads through the reapproximated C1 lateral masses directly onto the superior articular facets of C2. Furthermore, studies on the pure tensile load of the transverse ligament indicate that its biomechanical properties result in a failure load range of 380 to 1040 N, which far exceeds the weight of the skull.²⁰ Consequently, it is hypothesized that the fracture site will exhibit stable healing.

Clinically, at the 13-month postoperative follow-up, the patient’s angular motions at the C0 to C1 and C1 to C2 segments were partially rescued at 20° and 13°, respectively, compared with native physiological ranges (21.6°–34.4° for C0–C1; 15.8°–32.2° for C1–C2).^21,22 Furthermore, the patient reported that the range of rotation in the head and neck had been partially preserved in comparison with the preoperative state. The preservation of motor function in the upper cervical spine confirms the effectiveness of this nonrestrictive fixation strategy. Nevertheless, given the elongated “long lever arm effect” of the DISH and the occurrence of adjacent segment disease following surgery, there remains a risk of fracture recurrence in the upper cervical spine.^4,23

Conclusion

Pursuing long-segment fusion indiscriminately is not an alternative for patients with DISH exhibiting complex atlantoaxial fractures. This case suggests that after a comprehensive evaluation of fracture morphology and bone density, a nonrestrictive fixation strategy can be used as an alternative method to continuous long-segment arthrodesis. It can meet the local biomechanical demands required for fracture healing while maximizing the preservation of the patient’s residual upper cervical rotation and flexion-extension mobility. However, given that this study is predicated on a single case report, further biomechanical investigations and larger clinical cohorts are warranted to validate the long-term efficacy and reproducibility of this nonrestrictive fixation strategy.