Stabilization of the unstable upper cervical spine in rheumatoid arthritis

Update on imaging of the cervical spine in rheumatoid arthritis

Rheumatoid arthritis is a multisystem, autoimmune, inflammatory disorder with numerous musculoskeletal manifestations. Involvement of the cervical spine is common and may result in severe complications due to synovitis, erosions, pannus formation, spinal instability and ankylosis. The purpose of this article is to review the current role of imaging in the rheumatoid spine, with emphasis on radiographs and MRI.

Modification of Wright's technique for C2 translaminar screw fixation: technical note

PURPOSE

To describe a modification of Wright's technique for C2 translaminar screw fixation.

METHODS

Bilateral crossing C2 laminar screws have recently become popular as an alternative technique for C2 fixation. This technique is particularly useful in patients with anomalous anatomy, as a salvage technique where other modes of fixation have failed or as a primary procedure. However, reported disadvantages of this technique include breach of the dorsal lamina and spinal canal, early hardware failure and difficulty in bone graft placement due to the position of the polyaxial screw heads. To address some of these issues, a modified technique was used in six patients. In this technique, the upper part of the spinous process of C2 was removed and the entry point of the screw was in the base of this removed spinous process.

RESULTS

The screw position was satisfactory in all patients. There were no intraoperative or early postoperative complications.

CONCLUSIONS

Our modification enables placement of a bone graft on the C2 lamina and is also less likely to cause inadvertent cortical breach. Because of these advantages, it is especially suitable for patients with advanced rheumatoid arthritis with destruction of the lateral masses of C2 or as part of a hybrid construct in patients with a unilateral high-riding vertebral artery. This technique is not suitable for bilateral translaminar screw placement.

Occipitocervical fusion following the extreme lateral transcondylar approach

BACKGROUND

Modern cranial base approaches to the clivus and foramen magnum may threaten the stability of the cranio-cervical junction. This necessitates stabilization and fusion in some cases. We studied occipitocervical fusion after extreme lateral transcondylar approaches.

METHODS

Twenty-seven patients underwent an extreme lateral transcondylar approach over a 2-year period. Two patients were excluded because of prior occipitocervical fusion. The pathological diagnosis was meningioma in ten patients, chordoma in six patients, neurofibroma in two, and 10 patients had other tumoral and nontumoral pathologies.

RESULTS

Eight patients required occipitocervical fusion and stabilization. Five of six patients with chordomas required fusion, whereas no patient with a meningioma underwent fusion. All the patients who were fused had more than 70% resection of their occipital condyle. No patient with resection of less than 70% of the occipital condyle required fusion. Significant interference of the surgical construct with follow-up imaging was seen only in the patient in whom a stainless steel Steinman pin was used.

CONCLUSION

One third of patients will require fusion after extreme lateral transcondylar approaches. Most patients with less than 70% resection of the condyle remain stable without need for surgical intervention, whereas complete resection necessitates fusion in most cases.

Posterior C1-C2 transarticular screw fixation for atlantoaxial arthrodesis

OBJECTIVE

To assess the outcomes associated with C1-C2 transarticular screw fixation.

METHODS

The clinical outcomes of 121 patients treated with posterior C1-C2 transarticular screws and wired posterior C1-C2 autologous bone struts were evaluated prospectively. Atlantoaxial instability was caused by rheumatoid arthritis in 48 patients, C1 or C2 fractures in 45, transverse ligament disruption in 11, os odontoideum in 9, tumors in 6, and infection in 2.

RESULTS

Altogether, 226 screws were placed under lateral fluoroscopic guidance. Bilateral C1-C2 screws were placed in 105 patients; each of 16 patients had only one screw placed because of an anomalous vertebral artery (n = 13) or other pathological abnormality. Postoperatively, each patient underwent radiography and computed tomography to assess the position of the screw and healing. Most screws (221 screws, 98%) were positioned satisfactorily. Five screws were malpositioned (2%), but none were associated with clinical sequelae. Four malpositioned screws were reoperated on (one was repositioned, and three were removed). No patients had neurological complications, strokes, or transient ischemic attacks. Long-term follow-up (mean, 22 mo) of 114 patients demonstrated a 98% fusion rate. Two nonunions (2%) required occipitocervical fixation. In comparison, our C1-C2 fixations with wires and autograft (n = 74) had an 86% union rate.

CONCLUSION

Rigidly fixating C1-C2 instability with transarticular screws was associated with a significantly higher fusion rate than that achieved using wired grafts alone. The risk of screw malpositioning and catastrophic vascular or neural injury is small and can be minimized by assessing the position of the foramen transversaria on preoperative computed tomographic scans and by using intraoperative fluoroscopy and frameless stereotaxy to guide the screw trajectory.

Posterior atlantoaxial facet screw fixation in rheumatoid arthritis

OBJECT

This retrospective review was conducted to determine the efficacy of transarticular screw fixation in a group of patients who were treated for rheumatoid atlantoaxial instability.

METHODS

Thirty-six patients (mean age 63 years) with rheumatoid atlantoaxial instability were treated with posterior atlantoaxial transarticular screw fixation supplemented with an interspinous C1-2 strut graft-cable construct to provide immediate three-point fixation to facilitate bone fusion. Previous attempts at fusions by using bone grafting with wire fixation at other institutions had failed in six of these patients. Six patients underwent transoral odontoid resections for removal of large irreducible pannus as a first-stage procedure, which was followed within 2 to 3 days by the posterior procedure. Postoperatively, 33 patients were placed in hard cervical collars and three required halo vests because of severe osteoporosis. Of eight patients categorized as Ranawat Class II preoperatively, all eight returned to normal after surgery; of eight patients in Ranawat Class III-A preoperatively, four improved to Class II and four remained unchanged. All 20 patients classified as Ranawat Class I preoperatively recovered completely. Pain decreased or resolved in all patients, and there were no complications related to instrumentation. At follow-up review (mean 2 years), 33 patients (92%) had solid bone fusions, and three (8%) had stable fibrous unions.

CONCLUSIONS

Posterior atlantoaxial transarticular screw fixation provides a good surgical alternative for the management of patients with rheumatoid atlantoaxial instability. This technique provides immediate three-point rigid fixation of the C1-2 region, thus obviating the need for halo vest immobilization in most cases.

Predictors of outcome in the quadriparetic nonambulatory myelopathic patient with rheumatoid arthritis: a prospective study of 55 surgically treated Ranawat class IIIb patients

The functional results of surgery in patients with myelopathic nonambulatory rheumatoid arthritis (Ranawat Class IIIb) are often disappointing, with high rates of postoperative morbidity and mortality. The authors therefore undertook a detailed investigation of a cohort of 55 Ranawat Class IIIb patients (11 men and 44 women) with a mean age of 64.7 years who were recruited prospectively over a 10-year period (1983-1993), to determine what factors may accurately predict a good surgical outcome. Only 14 patients (25.5%) were judged to have had a favorable outcome as determined by an improvement to Ranawat Class I or II or an improvement of at least 0.5 points in the Stanford Health Assessment Questionnaire disability index. The early postoperative mortality rate was high (12.7%) in this group and almost one-quarter of the patients were dead within 6 months. These poor results mirror those already published in the existing literature. Univariate analysis revealed that age (p = 0.02), degree of vertical translocation (p = 0.05), and, more importantly, spinal cord area (p = 0.006) were significant predictors of outcome. Multiple logistic regression analysis showed that spinal cord area (p = 0.026) was, in fact, the major determinant of outcome and, indeed, of long-term survival (p = 0.001). The mean spinal cord area of those patients not achieving a good outcome was 44 mm2. The atlantodens interval (ADI) was not shown to be a significant outcome determinant, which may be explained by the correlation between an increasing vertical translocation and a decreasing ADI (r = 0.4, p = 0.01). Furthermore, as the degree of vertical translocation increased, the space available for the cord was observed to decrease (p = 0.003) commensurate with a reduction in spinal cord area (p = 0.02). Together, these findings strongly argue for earlier surgical intervention, before the development of vertical translocation, permanent neurological damage, and spinal cord atrophy can occur.

Surgery on the rheumatoid cervical spine for the non-ambulant myelopathic patient-too much, too late?

BACKGROUND

Opinions differ on the timing of surgery for rheumatoid arthritis patients with atlanto-axial subluxation. Some clinicians wait for development of neurological signs; others favour prophylactic fusion and decompression. We examined the results of surgery in relation to neurological state at the time of operation.

METHODS

134 patients underwent surgery for rheumatoid involvement of the cervical spine, after development of objective signs of myelopathy. Surgical outcomes were examined prospectively in two groups-patients who were still ambulant at the time of presentation (Ranawat class III A) and patients who had lost the ability to walk (Ranawat class III B)-by means of neurological and functional grading systems in conjunction with standard measures of postoperative morbidity and mortality.

FINDINGS

58% of the ambulant patients attained Ranawat neurological grades I or II compared with only 20% of the non-ambulant patients (p<0.0001). The non-ambulant group also fared worse in terms of postoperative complication rate, length of hospital stay, functional outcome, and ultimately survival. Radiologically, the non-ambulant patients were characterised by a smaller cross-sectional spinal cord area.

INTERPRETATION

The strong likelihood of surgical complications, the poor survival, and the limited prospects for functional recovery in non-ambulant patients make a strong case for earlier surgical intervention. At a late stage of disease most patients will have irreversible cord damage.

Atlantoaxial stabilization in rheumatoid arthritis

Atlantoaxial subluxation in patients with rheumatoid arthritis is common. Operative stabilization is clearly indicated when signs and symptoms of spinal cord compression occur. However, many recommend early operative fusion before evidence of appreciable neural compression occurs because 1) the myelopathy in these patients may be irreversible; 2) the overall prognosis is poor once symptoms of cord compression are present; and 3) the risk of sudden death associated with atlantoaxial subluxation is increased even in asymptomatic patients. The authors believe that rheumatoid arthritis patients in relatively good health without advanced multisystem disease and less than 65 years of age should be considered for operative stabilization if mobile atlantoaxial subluxation is greater than 6 mm. Seventeen patients with severe rheumatoid arthritis and atlantoaxial subluxation treated with a posterior arthrodesis are presented. A new method of fusion, devised by the senior author (V.K.H.S.), was utilized in all cases. Indications for operative therapy in these patients included evidence of spinal cord compression in 11 patients (65%) and mobile atlantoaxial subluxation greater than 6 mm but no signs or symptoms of cord compression in six patients (35%). Thirteen patients developed a stable osseous fusion, two patients a well-aligned fibrous union, one patient a malaligned fibrous union, and one patient died prior to evaluation of fusion stability. The details of the operative technique and management strategies are presented. Several technical advantages of this method of fusion make this approach particularly useful in patients with rheumatoid arthritis. Because of multisystem involvement of this disease, a high rate of osseous fusion is often difficult to achieve.