Failure of posterior titanium atlantoaxial cable fixation

Atlantoaxial wiring hardware failure resulting in intracranial hemorrhage and hydrocephalus: illustrative case

BACKGROUND

Atlantoaxial sublaminar wiring has many known complications related to hardware failure, but intracranial hemorrhage is a rare complication.

OBSERVATIONS

A 61-year-old female patient with prior atlantoaxial sublaminar wiring for odontoid fracture nonunion experienced decreased level of consciousness due to a subarachnoid and subdural hemorrhage of the posterior fossa with intraventricular extension and hydrocephalus. Rupture of the sublaminar wire with intramedullary protrusion was the cause of the hemorrhage. The patient was treated with ventriculostomy for hydrocephalus and occipital cervical fusion for spinal instability, along with removal of the broken wire and drainage of a hematoma.

LESSONS

This uncommon cause of intracranial hemorrhage highlights an additional risk of atlantoaxial sublaminar wiring compared with other atlantoaxial fusion techniques. In addition, this case suggests cervical instrumentation failure as a differential diagnosis of subarachnoid and subdural hemorrhage of the posterior fossa when a history of prior instrumentation is known.

The Effect of Straight or Lordotic Rods on Cervical Subaxial Alignment While Fusing C1-C2

BACKGROUND

The C1 lateral mass and C2 pedicle screw with rod fixation system has been used commonly in recent years. Despite the numerous reports on this technique in the literature, there are no studies regarding the effect of the angle of the rod used. We investigated the effect of rod angle on subaxial lordosis, cervical sagittal balance, and pain scores.

METHODS

Clinical records and radiologic images of 58 patients who underwent procedures between 2011 and 2016 at our clinic were assessed retrospectively. We recorded clinical findings, visual analog scale (VAS) scores, angles of cervical and segmental lordosis, and the distance between the C2 sagittal vertical axis (SVA) and the C7 posterior-superior corner.

RESULTS

A total of 36 male and 22 female patients were enrolled. A negative correlation was found between the C1-C2 lordosis angle and the C2-C7 lordosis angle irrespective of surgical technique. In patients who were operated on using 30°-angled rods, there was a postoperative increase in C1-C2 lordosis degree and an improvement in C2 cervical SVA values. Postoperative month 6 VAS scores were significantly better in the patients who were operated on with angled rods compared with those who received straight rods.

CONCLUSIONS

We believe this is because of the positive effect of the angled rod on sagittal balance. Nevertheless, prospective case-control studies should be conducted with larger groups of subjects. Furthermore, every patient should be evaluated considering the whole spinal sagittal balance.

Migration of titanium cable into spinal cord and spontaneous C2 and C3 fusion: Case report of possible causes of fatigue failure after posterior atlantoaxial fixation

INTRODUCTION

Atlantoaxial instability is a common and serious injury of the upper cervical spine. Brooks' procedure is widely used to reconstruct the unstable atlantoaxial joint. The migration into spinal cord of titanium cable and spontaneous fusion between C2 and C3 has been little reported and the management of such a patient is difficult. We describe an unusual case of fatigue failure of posterior titanium atlantoaxial cable fixation with migration into the spinal cord and spontaneous fusion between C2 and C3.

CASE REPORT

A 16-year-old girl complained of cervico-occipital pain with numbness and weakness of extremities 3 months ago. The girl underwent posterior C1-C2 arthrodesis with titanium cables and autogenous iliac crest bone grafting when she was 6 years old. When presented to our emergency department, imaging revealed the cracked titanium atlantoaxial cable and the spontaneous fusion between C2 and C3. Computed tomography demonstrated a broken wire with anterior migration of the cable into the spinal cord. The patient underwent posterior approach cervical spinal surgery to remove the broken cables. She remains neurologically intact a year following the posterior approach cervical spine surgery.

CONCLUSIONS

Brooks' posterior stabilization could not effectively control rotation at the atlantoaxial articulation, so surgeons must be aware of the potential of fatigue failure of cables as well as the possibility of its migration into the spinal cord when using Brooks' posterior stabilization. Bilateral C1 lateral mass and C2 pedicle screw fixation or transarticular screw fixation are recommended by the authors in the event of rotatory instability.

A comparison of the Gallie technique and casting versus the harms technique for the treatment of odontoid fractures

OBJECTIVE

The objective of this study was to compare perioperative, clinical parameters, complications, and reoperation rate of the Gallie technique and head-neck-chest plaster with the Harms technique in the treatment of odontoid fractures.

DESIGN

A retrospective study.

SETTING

Level I spine center.

PATIENTS

Fifty-seven patients with odontoid fractures treated either with the Gallie technique and casting or the Harms technique between July 2002 and June 2008.

INTERVENTION

Surgery.

MAIN OUTCOME MEASUREMENTS

At a minimum of 2-year follow-up, comparison of the two groups was conducted in terms of hospital stay, blood loss, operation time, cost of the first admission, total cost, time to fusion, time to return to previous occupation, Japanese Orthopedic Association scores, visual analog scale scores of neck pain, complications (nonunion, delayed union, hardware breakage, wound infection), and reoperation rate.

RESULTS

There were no significant differences in terms of hospital stay, time to fusion, Japanese Orthopedic Association scores, neck pain visual analog scale scores, complications, or reoperation rate between the two groups. Blood loss, operation time, cost of the first admission, and total cost were significantly lower in the Gallie group than that in the Harms group. However, the Gallie group took longer to return to previous occupation than the Harms group (P < 0.001).

CONCLUSIONS

Management of odontoid fractures by either the Gallie technique and casting or the Harms technique was found to be similar in clinical outcomes. Although the Harms technique was associated with more blood loss, operation time, and cost, the Harms technique was found to be superior to the Gallie technique with casting in terms of time to return to previous occupation.

Intracranial hemorrhage and spinal cord injury from a fractured C1-C2 sublaminar cable: case report

OBJECTIVE

This is a unique case report of a fractured atlantoaxial interspinous multistranded cable leading to intracranial hemorrhage and spinal cord injury.

CLINICAL PRESENTATION

A 61-year-old woman, with a history of rheumatoid arthritis and C1-C2 interspinous wiring with allograft for atlantoaxial instability, presented with neck pain and progressive decline in mental status. Prior to transfer to our institution from a referral hospital, imaging studies revealed progressive hydrocephalus with interval development of subarachnoid and fourth ventricular hemorrhage. Initial and repeat angiographic work-up was negative for vascular lesions. Magnetic resonance imaging revealed a subdural hematoma and signal changes at the cervicomedullary junction. Computed tomography of the cervical spine revealed a fractured interspinous cable, intradural penetration, and atlantoaxial instability.

INTERVENTION

After ventriculostomy, both the patient's mental status and quadriparesis improved to a C on the American Spinal Injury Association (ASIA) scale. During surgery, the fractured cable and subdural hematoma were removed revealing an area of spinal cord impalement. She underwent C1-C3 lateral mass fixation with iliac crest autograft for fusion and was discharged to rehabilitation after a ventriculoperitoneal shunt was placed. At her 6-month follow-up, she was independent and had improved to ASIA E. Computed tomography confirmed fusion.

CONCLUSION

Spinal instrumentation eventually fails from pseudarthrosis and can cause neurological injury. In patients with atlantoaxial instability, direct C1-C2 screw fixation with posterior interspinous wiring using autograft offers the best chance for fusion. Cervical spine pathology can cause intracranial hemorrhage, and unconventional causes of injury must be considered when routine workup is negative.

Subaxial sagittal alignment and adjacent-segment degeneration after atlantoaxial fixation performed using C-1 lateral mass and C-2 pedicle screws or transarticular screws

Object

The purpose of this study was to evaluate the effect of a fixed atlantoaxial angle on subaxial sagittal alignment, and that of atlantoaxial fixation on adjacent-segment motion and degeneration.

Methods

The authors retrospectively reviewed 65 patients in whom atlantoaxial instability was treated with atlantoaxial fixation by C-1 lateral mass and C-2 pedicle screw fixation (30 patients, Goel-Harms [GH] group) or a combination of transarticular screw fixation and posterior wiring (35 patients, Magerl-Brooks [MB] group). Angles of Oc–C1, C1–2, C2–3, and C2–7 were determined based on an upright lateral radiograph in flexion, neutral, and extension positions. The range of motion (ROM) at Oc–C1 and C2–3 was also determined. All patients were examined before and 2 years after surgery.

Results

The mean preoperative atlantoaxial angles in the GH and MB groups were 20.9 ± 8.3° and 18.3 ± 7.2°, respectively, and the mean postoperative atlantoaxial angles in the same groups were 23.5 ± 5.6° and 29.7 ± 6.3°, respectively, with a statistically significant difference between the 2 groups (p < 0.05). The mean preoperative angles of C2–7 in the GH and MB groups were 15.4 ± 7.8° and 13.7 ± 9.5°, respectively, and after surgery, the angles were 11.8 ± 12° and 2.48 ± 12°, respectively, with a statistically significant difference between the 2 groups (p < 0.05). The postoperative angle of C1–2 showed a negative correlation with the extent of change observed in the C2–7 angle preand postoperatively in each of these 2 surgical procedures. The Oc–C1 ROM increased after surgery in both groups, but the difference was not statistically significant (p = 0.38). The C2–3 ROM decreased after surgery in both groups, and the difference was statistically significant (p < 0.05).

Conclusions

Atlantoaxial fixation in a hyperlordotic position produced kyphotic sagittal alignment after surgery in both GH and MB groups. Reduction of the atlantoaxial joint can be easily achieved through screw fixation at an optimal angle, thereby ameliorating the risk for subsequent subaxial kyphosis. Degeneration of lower adjacent segments appeared to be less with this procedure compared with using a combination of transarticular screw fixation and posterior wiring.

Efficacy and durability of the titanium mesh cage spacer combined with transarticular screw fixation for atlantoaxial instability in rheumatoid arthritis patients

STUDY DESIGN

A retrospective study.

OBJECTIVE

This retrospective investigation was conducted to determine efficacy and endurance of titanium mesh cage as a strut for interlaminar wiring by comparing with autologous iliac bone graft (AIBG). For patients with atlantoaxial instability (AAI), allograft bone was harvested on an interlaminar mesh cage and transarticular fixation (TAF) was performed.

SUMMARY OF BACKGROUND DATA

There have been few studies about atlantoaxial fusion rate and advantages for titanium mesh cage from comparison with AIBG in rheumatoid arthritis (RA) patients.

METHODS

Between January 1998 and October 2007, 55 RA patients were surgically treated for AAI. Among them, 34 patients who underwent surgical treatment with TAF and interlaminar wiring using mesh cage packed with allograft, enrolled in this study (group I). For evaluation of bone fusion about mesh cage group, 21 RA patients who underwent TAF and interlaminar wiring with AIBG were also selected (group II). In both groups, radiologic evidence of bone fusion was assessed with measuring atlantodental interval. Patients were strongly encouraged to mobilize by postoperative 1 day with external cervical bracing. The mean follow-up period was 12.3 months (6-36 months).

RESULTS

Overall, bone fusion was achieved in 33 patients (97%) in group I. And, this was comparable with 100% of group II. There was no statistical difference in bone fusion rate. During the study period, there were 2 instrument-related complications of screw malposition and cable loosening.

CONCLUSION

The results of this study in which mesh cage was used as an interlaminar spacer, showed immediate rigid fixation and successful bone union. We also could prevent donor site morbidities frequently seen in patients with surgical treatment for AAI.

Clinical Study of a Modified Brooks Technique for Atlanto-axial Subluxation Using Polyethylene Tape

Forty-four patients, 15 males and 29 females (3-71 years old; mean age, 52.9), were treated for the control of cervical instability with a modified Brooks operation using Tekmilon tape (an ultrahigh molecular weight polyethylene tape) instead of metal wires. Forty of the patients had rheumatoid arthritis (RA) with atlanto-axial subluxation (AAS), three patients had os odontoideum, and one patient had a cervical spine injury. The mean follow-up period was 8 years and 4 months. These patients were divided into three groups: 30 years or less, 31 to 60 years, and over 60 years. Atlanto-dental interval (ADI), inclination angle of atlanto-axial vertebrae (A-A angle), and bone fusion were examined on plain radiographs. The proportion of patients with reduced neck pain (Ranawat's grade 0 or grade 1) increased from 42.5% to 97.9% at the time of postoperative evaluation. Surgical complications, such as dural tear, lamina fracture, and spinal cord injury did not occur in any cases. Thirty-nine patients (88.6%) achieved bone union. ADI in the maximum flexed position improved from 10.3 to 2.5 mm. There was no statistical difference between ADI in males and females. ADI did not change in any age group both before and after surgery. A-A angle also improved from 9.4 to 24.4 degrees. The polyethylene tapes, used for internal fixation, caused no neurologic complications during sublaminar wiring and produced no MR artifacts. This modified Brooks technique using Tekmilon tape was proved to be a simple and safe treatment of AAS.

Frameless Stereotactic Image-Guided C1-C2 Transarticular Screw Fixation for Atlantoaxial Instability

OBJECTIVE

We retrospectively studied 20 adults who underwent C1-C2 transarticular screw (TAS) fixation utilizing frameless stereotaxy.

METHODS

The study group comprised 13 men and 7 women, with a mean age of 63 years (range 12-87 years). All patients demonstrated clinical and radiographic evidence of C1-C2 instability. The cause of the instability was trauma in 11 patients, rheumatoid arthritis in 6 patients, failed prior surgery in 2 patients, and congenital malformation in 1 patient. All patients underwent stabilization with C1-C2 TASs using image-guided frameless stereotaxy.

RESULTS

There were no new or worsening neurologic symptoms reported at 18-month follow-up. Motor weakness improved in seven of nine patients, myelopathy in seven of seven, and gait in three of six patients in whom these deficits were present preoperatively. Postoperative complications included one surgical site abscess, one cutaneous pressure ulcer, and one iliac crest donor site infection. Of 36 screws placed, 33 (92%) were well positioned. Normal C1-C2 alignment was achieved in 17 of 20 (85%) patients. In 4 of 20 cases, screw implant, which was thought to be anatomically difficult, if not impossible, on the basis of routine magnetic resonance or computed tomography imaging, was actually accomplished successfully using surgical navigation.

CONCLUSIONS

C1-C2 TAS placement is a safe and accurate surgical technique that may improve neurologic function. Use of intraoperative navigation can facilitate achieving difficult surgical trajectories that match the patient's anatomy, thus allowing TAS implant in patients who otherwise would not be candidates for this type of internal fixation.

A comparison of the fatigue behavior of cast Ti-7.5Mo with c.p. titanium, Ti-6Al-4V and Ti-13Nb-13Zr alloys

The purpose of the present study is to compare the high-cycle fatigue behavior of newly developed Ti-7.5Mo alloy with that of c.p. Ti, Ti-13Nb-13Zr and Ti-6Al-4V alloys in their as-cast state. Experimental results indicate that Ti-6Al-4V and c.p. Ti have higher stress-controlled fatigue resistance but lower strain-controlled fatigue resistance than Ti-7.5Mo and Ti-13Nb-13Zr. Among four materials Ti-7.5Mo demonstrates the best strain-controlled fatigue performance. The fracture surfaces of the present materials are comprised of three morphologically distinct zones: crack initiation zone, crack propagation zone, and the final-stage overload zone. The fatigue cracks almost always initiate from casting-induced surface/subsurface pores. A river pattern is observed in the propagation zone. In the overload zone dimples are typically observed. Three factors most significantly affecting the fatigue performance of the present materials are the presence of the casting-induced surface/subsurface pores; the location of the pores; and the inherent mechanical properties of the materials.

A safe screw trajectory for atlantoaxial transarticular fixation achieved using an aiming device

STUDY DESIGN

A retrospective evaluation and characterization of the trajectory of atlantoaxial transarticular screws inserted using an aiming device.

OBJECTIVES

To confirm that the screws were inserted through the safest trajectory, which is through the most dorsal and medial part of the isthmus of C2, and to characterize the trajectory on lateral radiograms by comparison with historical controls.

SUMMARY OF BACKGROUND DATA

Posterior atlantoaxial transarticular screw fixation entails the potential risk of vertebral artery (VA) injury, which may be lethal. Although much literature recommends that the screws should be inserted aiming at the anterior arch of C1, the authors considered that the safest screw path is via the most dorsal and medial part of the isthmus regardless of the C1 anterior arch, and have used an original aiming device to achieve this trajectory.

METHODS

Forty-three consecutive patients who submitted to atlantoaxial transarticular screw fixation using the aiming device were evaluated for screw position using computed tomography (CT) and lateral radiogram. The medialization index (the distance between the screw and the cortex of the spinal canal of C2 on axial CT) and the dorsalization index (the thickness of the bone remaining dorsal to the screw at the isthmus of C2 on sagittal reconstruction CT) were measured. Further, three parameters on the lateral radiograms of these patients were compared with those in the literature and those of our previous cases performed without the aiming device.

RESULTS

Neither VA injury nor violation of the spinal canal was encountered, although 12 high-riding VAs were included in this series. The mean medialization index was 0.21 mm, and the indexes of 86.3% of the screws were zero. The mean dorsalization index was 0.36 mm, and the indexes of 76.8% of the screws were zero. These results demonstrated that most of the screws were inserted as aimed, proving the usefulness of the aiming device. The trajectory of these screws on lateral radiograms was characterized by significantly less bone thickness dorsal to the screw at the isthmus compared with the two control groups. As a result, more screws were pointed above the anterior arch of C1.

CONCLUSIONS

The atlantoaxial transarticular screw was inserted safely as aimed by using the aiming device. The trajectory was characterized by less bone thickness dorsal to the screw on lateral radiogram, which should be a new intraoperative landmark for screw insertion, in place of the anterior arch of C1.

Posterior Instrumentation Surgery for Craniocervical Junction Instabilities: an Update

The surgical treatment of craniocervical junction (CCJ) instability has recently undergone significant development and change. Posterior instrumentation surgery has been the mainstay of treatment of CCJ instability, and is the focus of this review. For the treatment of atlantoaxial instability, C1-2 transarticular screw fixation has shown good stability, and has been regarded as the "gold standard" procedure. Because of potentially hazardous complications including vertebral artery injury, however, C-1 lateral mass-C-2 pedicle screw fixation is gaining popularity. For treatment of atlantooccipital instability, occipitocervical fixation using screw constructs (combined with either rods or plates) has shown more stability than sublaminar wiring techniques, and has been utilized more frequently. Both innovation in material engineering and in vitro biomechanical studies have contributed significantly to the development of more rigid internal fixation devices, and as a result, many patients who would have been treated conservatively with external orthosis are treated nowadays with instrumentation surgery, resulting in earlier ambulation, shortened hospital stay, and earlier recovery into social activities. New surgical techniques and instruments, however, need to stand the test of time to see whether they are free from long-term adverse events. The rapid turnover of new surgical techniques and hardware has made it difficult for less experienced surgeons to keep up with the latest developments. Conventional techniques can be safer and less technically demanding than newer techniques for those who are not familiar with them.