STRANGULATION-INDUCED ATLANTOAXIAL ROTATORY SUBLUXATION TREATED WITH CLOSED REDUCTION.

BACKGROUND: Cervical subluxation is a broad class of injuries in which there are degrees of misalignment of vertebral bodies in relationship to adjacent vertebra. Atlantoaxial rotatory subluxation (AARS) is a subtype of cervical subluxation resulting from exaggerated rotation of the C1-C2 complex. Inflammatory, infectious, post-surgical, and traumatic etiologies are recognized and well-described. AARS is predominantly seen in children and occurs rarely in adults. CASE REPORT: We submit the case of an otherwise healthy adult male patient presenting to the emergency department with strangulation-induced C1-C2 subluxation with a rotational component that was treated at the bedside by neurosurgery with closed reduction. Why Should an Emergency Physician Be Aware of This? Clinicians must consider a broad range of serious pathologies in a patient presenting with torticollis, especially in the setting of strangulation. Although extremely rare in adults, AARS must be considered in the differential diagnosis, as early identification increases the likelihood of successful nonoperative treatment.

[Atlantoaxial rotatory subluxation - a cause of torticollis in children]. / Atlantoaxial subluxation kan vara en orsak till tortikollis hos barn.

Atlantoaxial rotatory subluxation is an important differential diagnosis in young children with torticollis. The condition rarely results in neurological deficits. Radiological examinations such as computer tomography (CT) and magnetic resonance imaging (MRI) are useful to determine the diagnosis. It is important for doctors in all areas of healthcare to be aware of the condition, as persistent problems or surgery can be avoided by early detection and treatment.

Dissection of mendelian predisposition and complex genetic architecture of craniovertebral junction malformation.

The craniovertebral junction (CVJ) is an anatomically complex region of the axial skeleton that provides protection of the brainstem and the upper cervical spinal cord. Structural malformation of the CVJ gives rise to life-threatening neurological deficits, such as quadriplegia and dyspnea. Unfortunately, genetic studies on human subjects with CVJ malformation are limited and the pathogenesis remains largely elusive. In this study, we recruited 93 individuals with CVJ malformation and performed exome sequencing. Manual interpretation of the data identified three pathogenic variants in genes associated with Mendelian diseases, including CSNK2A1, MSX2, and DDX3X. In addition, the contribution of copy number variations (CNVs) to CVJ malformation was investigated and three pathogenic CNVs were identified in three affected individuals. To further dissect the complex mutational architecture of CVJ malformation, we performed a gene-based rare variant association analysis utilizing 4371 in-house exomes as control. Rare variants in LGI4 (carrier rate = 3.26%, p = 3.3 × 10-5) and BEST1 (carrier rate = 5.43%, p = 5.77 × 10-6) were identified to be associated with CVJ malformation. Furthermore, gene set analyses revealed that extracellular matrix- and RHO GTPase-associated biological pathways were found to be involved in the etiology of CVJ malformation. Overall, we comprehensively dissected the genetic underpinnings of CVJ malformation and identified several novel disease-associated genes and biological pathways.

Neck pain and related factors in patients with rheumatoid arthritis.

OBJECTIVES: In rheumatoid arthritis, neck pain can be caused by inflammatory reactions or cervical lesions, but the prevalence and associated factors have not been well studied. This study aimed to investigate the prevalence of neck pain in patients with rheumatoid arthritis and elucidate the related factors. METHODS: This study included 146 patients with rheumatoid arthritis. Neck pain, quality of life, and levels of anxiety and depression were evaluated using a questionnaire. Cervical lesions and spinal alignment were evaluated using plain radiograph and magnetic resonance imaging. Factors associated with neck pain were analysed using a logistic regression model. RESULTS: Fifty-six per cent of the patients had neck pain, and the quality of life scores were significantly worse in these patients. Multivariate analysis revealed age, C7 sagittal vertical axis, upper cervical lesion, and endplate erosion as factors associated with neck pain in patients with rheumatoid arthritis. CONCLUSIONS: More than half the patients with rheumatoid arthritis suffer from neck pain, and neck pain affects the quality of life and activities of daily living. Neck pain was associated with upper cervical lesion and endplate erosion suggesting the importance of radiological examination in patients with rheumatoid arthritis and neck pain.

Imaging Characterization of Non-Rheumatoid Retro-Odontoid Pseudotumors: Comparison with Atlantoaxial Manifestation of Rheumatoid Arthritis.

Backgroundand Objectives: To date, imaging characterization of non-rheumatic retro-odontoid pseudotumors (NRROPs) has been lacking; therefore, NRROPs have been confused with atlantoaxial joint involvement of rheumatoid arthritis (RA). It is important to differentiate these two disease because the treatment strategies may differ. The purpose of this study is to characterize imaging findings of NRROPs and compare them with those of RA. Material and Methods: From January 2015 to December 2019, 27 patients (14 women and 13 men) with NRROPs and 19 patients (15 women and 4 men) with RA were enrolled in this study. We evaluated various imaging findings, including atlantoaxial instability (AAI), and measured the maximum diameter of preodontoid and retro-odontoid spaces with magnetic resonance imaging (MRI) and computed tomography (CT). Results: Statistical significance was considered for p < 0.05. AAI was detected in eight patients with NRROPs and in all patients with RA (p < 0.0001). Seventeen patients with NRROPs and six patients with RA showed spinal cord compression (p = 0.047). Compressive myelopathy was observed in 14 patients with NRROPs and in 4 patients with RA (p = 0.048). Subaxial degeneration was observed in 25 patients with NRROPs and in 9 patients with RA (p = 0.001). Moreover, C2-3 disc abnormalities were observed in 11 patients with NRROPs and in 2 patients with RA (p = 0.02). Axial and longitudinal diameter of retro-odontoid soft tissue and preodontoid and retro-odontoid spaces showed significant differences between NRROP and RA patients (p < 0.0001). Furthermore, CT AAI measurements were differed significantly between NRROP and RA patients (p < 0.05). Conclusions: NRROPs showed prominent retro-odontoid soft tissue thickening, causing compressive myelopathy and a high frequency of subaxial and C2-3 degeneration without AAI.

Determination of cutoff values on computed tomography and magnetic resonance images for the diagnosis of atlantoaxial instability in small-breed dogs.

OBJECTIVE: To determine cutoff values for the diagnosis of atlantoaxial instability (AAI) based on cross-sectional imaging in small-breed dogs. STUDY DESIGN: Retrospective multicenter study. SAMPLE POPULATION: Client-owned dogs (n = 123) and 28 cadavers. METHODS: Dogs were assigned to three groups: a control group, a "potentially unstable" group, and an AAI-affected group, according to imaging findings and clinical signs. The ventral compression index (VCI), cranial translation ratio (CTR), C1-C2 overlap, C1-C2 angle, atlantoaxial distance, basion-dens interval, dens-to-axis length ratio (DALR), power ratio, and clivus canal angles were measured on CT or T2-weighted magnetic resonance (MR) images. Receiver operating characteristic (ROC) analysis was performed to define cutoff values in flexed (≥25°) and extended (<25°) head positions. RESULTS: Cutoff values for the VCI of ≥0.16 in extended and ≥0.2 in flexed head positions were diagnostic for AAI (sensitivity of 100% and 100%, specificity of 94.54% and 96.67%, respectively). Cutoff values for the other measurements were defined with a lower sensitivity (75%-96%) and specificity (70%-97%). A combination of the measurements did not increase the sensitivity and specificity compared with the VCI as single measurement. CONCLUSION: Cutoff values for several imaging measurements were established with good sensitivity and specificity. The VCI, defined as the ratio between the ventral and dorsal atlantodental interval, had the highest sensitivity and specificity in both head positions. CLINICAL SIGNIFICANCE: The use of defined cutoff values allows an objective diagnosis of AAI in small-breed dogs. The decision for surgical intervention, however, should remain based on a combination of clinical and imaging findings.

Cervical Myelopathy Due to Idiopathic Retro-odontoid Pseudotumor.

OBJECTIVE: A retro-odontoid pseudotumor (ROP) is commonly associated with atlantoaxial instability or rheumatoid arthritis. However, ROP in the absence of atlantoaxial instability or rheumatoid arthritis, which is termed idiopathic ROP (IROP), is a rare condition. The pathomechanisms and optimal treatment strategies for IROP remain controversial. The aim of the present study was to evaluate the radiographic and clinical characteristics of IROP patients and to assess the efficiency of atlantoaxial/occipitocervical fusion on IROP regression. METHODS: Data from 5 patients diagnosed with IROP were retrospectively reviewed. Posterior atlantoaxial or occipitocervical fixation and fusion were performed in 4 patients and C1 posterior arch resection alone in 1 patient. The patients' features, surgical procedures, and complications were recorded. The retro-odontoid soft tissue thickness was measured on preoperative and postoperative magnetic resonance imaging to evaluate IROP regression. RESULTS: The mean follow-up time was 37 months. ROP regression was achieved in patients who received atlantoaxial/occipitocervical fusion, but not for the patient with C1 posterior resection alone. There were no observed neurovascular complications associated with surgery. CONCLUSIONS: IROP was related to a restricted range of motion of the subaxial spine. Upper cervical fixation is an optional treatment that produces IROP regression over time. By contrast, direct removal of the IROP is unnecessary.

Genetically predicted C-reactive protein mediates the association between rheumatoid arthritis and atlantoaxial subluxation.

Objective: Investigating the causal relationship between rheumatoid arthritis (RA) and atlantoaxial subluxation (AAS) and identifying and quantifying the role of C-reactive protein (CRP) as a potential mediator. Methods: Using summary-level data from a genome-wide association study (GWAS), a two-sample Mendelian randomization (MR) analysis of genetically predicted rheumatoid arthritis (14,361 cases, and 43,923 controls) and AAS (141 cases, 227,388 controls) was performed. Furthermore, we used two-step MR to quantitate the proportion of the effect of c-reactive protein-mediated RA on AAS. Results: MR analysis identified higher genetically predicted rheumatoid arthritis (primary MR analysis odds ratio (OR) 0.61/SD increase, 95% confidence interval (CI) 1.36-1.90) increased risk of AAS. There was no strong evidence that genetically predicted AAS had an effect on rheumatoid arthritis risk (OR 1.001, 95% CI 0.97-1.03). The proportion of genetically predicted rheumatoid arthritis mediated by C-reactive protein was 3.7% (95%CI 0.1%-7.3%). Conclusion: In conclusion, our study identified a causal relationship between RA and AAS, with a small proportion of the effect mediated by CRP, but a majority of the effect of RA on AAS remains unclear. Further research is needed on additional risk factors as potential mediators. In clinical practice, lesions of the upper cervical spine in RA patients need to be given more attention.

Cervical spine tenosynovial giant cell tumor involving the atlantoaxial joint in a pediatric patient with medulloblastoma.

Tenosynovial giant cell tumor (TGCT) is a benign condition that arises from tendon sheaths, synovium, or bursae and is classified according to the site of involvement (intra-articular versus extra-articular) and pattern of growth (localized versus diffuse). The diffuse form tends to present as peri-articular masses and are locally aggressive. It usually presents as a mono-articular process affecting larger joints. Spinal involvement is extremely rare, particularly the cervical spine. In this case report, we present a pediatric case of spinal TGCT involving the C1-C2 joint which was incidentally detected in a 13-year-old girl undergoing surveillance for medulloblastoma recurrence. Although spinal TGCT is a benign condition, it remains a diagnostic challenge, which specific to our case can raise the concern for malignancy or metastasis. We also described a percutaneous biopsy approach using a spring-loaded blunt tip coaxial needle to avoid inadvertent vascular injury. The imaging features of spinal TGCT and biopsy approach for atlantoaxial lesion are discussed together with a comprehensive review of the literature.

Preoperative Cyst Formation as a Predictive Feature of Spontaneous Regression of Retro-Odontoid Pseudotumor After Posterior Fusion.

OBJECTIVE: Although the spontaneous regression of pseudotumors after posterior fusion has been reported, the predictive factors remain unclear. We examined the radiological features that predict for the regression of retro-odontoid pseudotumors after posterior fusion, with a specific focus on cyst formation. METHODS: We included 28 patients with a diagnosis of retro-odontoid pseudotumor using preoperative magnetic resonance imaging. The radiographic parameters and pseudotumor thickness were measured pre- and postoperatively. The regression rate for each pseudotumor was calculated. The presence of a cyst around the retro-odontoid pseudotumor was investigated. If present, the cyst thickness was measured. To elucidate the predictors for the postoperative regression of pseudotumors, the patients were divided into 2 cohorts: the regression group with a regression rate >40% and the no-regression group with a regression rate of <40%. Multivariate logistic regression analysis, including the demographic data and preoperative radiographic parameters as independent variables, was performed. RESULTS: The mean pseudotumor size had decreased significantly from 8.8 ± 3.6 mm preoperatively to 5.3 ± 2.0 mm postoperatively (P < 0.0001). The mean regression rate was 35.9% during a magnetic resonance imaging follow-up period of 8.6 months (range, 6-12 months). Cystic lesions were noted in 10 patients (35.7%) preoperatively. The mean cyst size was 4.7 ± 1.9 mm. All cysts were located dorsal to the pseudotumors and were involved at the maximum spinal compression levels. Nevertheless, all the cysts had disappeared postoperatively. Multivariate logistic regression analysis revealed that the pseudotumor regression group had had a significantly greater proportion of cysts (57.1% vs. 14.3%; odds ratio, 11.7; P = 0.013). CONCLUSIONS: The presence of cystic lesions protruding from retro-odontoid pseudotumors might serve as a predictive factor for the spontaneous regression of pseudotumors after posterior fusion.

Surgical treatment for upper cervical deformity with atlantoaxial joint dislocation using individualized 3D printing occipitocervical fusion instrument: A case report and literature review.

ABSTRACT: To introduce a novel technique of using individualized 3D printing occipitocervical fusion instrument (3D-OCF) for the treatment of upper cervical deformity with atlantoaxial joint dislocation.The surgery for deformity of the craniocervical junction area is a challenge in the field of spine. If the surgical deviation is too large to injure the spinal cord or vertebral artery, it will cause catastrophic damage to the patient. Therefore, it is controversial whether these patients should undergo surgical treatment. We provide a novel surgical approach for the challenging upper cervical surgery through 3D-OCF and a typical patient.We present a 54-year-old female patient, who suffered from dizziness and numbness in her limbs for 8 months. After the patient was admitted, we performed the three-dimensional CT scan, modeled using Mimics software 17.0, and designed customized occipitocervical fusion instrument. Besides, we repeatedly perform simulated surgery based on 3D-printed models before surgery.The operative time was 142 minutes and the intraoperative blood loss was 700 mL. X-ray showed reduction of atlantoaxial dislocation and accurate position of internal fixation. The patient's symptoms were significantly relieved: the sensation of dizziness and numbness of limbs was obviously relieved, and the sense of banding in chest, abdomen, and ankle was disappeared. At the last follow-up, imaging showed that 3D-OCF had bone-integration and Syringomyelia was disappeared. The patient's cervical JOA (Japanese Orthopaedic Association) score increased from 10 points to 17 points.Individualized 3D-OCF can improve the safety and accuracy of upper cervical surgery, reduce the operative time and the number of fluoroscopy. Our study provides a novel surgical approach for the challenging upper cervical surgery.

Dorsal Atlantoaxial Ligament Hypertrophy as a Cause for Clinical Signs in Dogs with Dens Abnormalities.

The objective of this study is to suggest clinical and subclinical atlantoaxial (AA) instability as a cause for dorsal AA ligament hypertrophy responsible for clinical signs in dogs with dens abnormalities. Clinical information from five dogs with malformed dens and dorsal spinal cord compression at the AA junction was collected. All dogs had neck pain, associated with tetraparesis in three cases. Radiological examination revealed hypoplastic dens in two dogs and a defect in its ossification in the other three. Stress views were able to demonstrate obvious AA instability only in two cases, but it was suspected in the other owing to response to surgical fixation of the joint and the presence of a dorsal compressive band, which was considered an enlarged dorsal AA ligament. Surgical and histopathological examination of compressive tissue confirmed hypertrophy of the ligament. Long-term prognosis in the four operated cases, either by dorsal decompression and ventral fixation or by ventral fixation alone, was excellent. A malformed dens can cause subclinical instability, unnoted in dynamic studies. As instability may lead to hypertrophy of joint ligaments, soft tissue changes (specifically dorsal AA ligament hypertrophy) points out this instability and the need for joint fixation if surgical management is required.

An Intraoperative Surprise! A Rare Case Report of Primary Craniovertebral Junction Hydatid Disease Mimicking a Bony Tumor.

BACKGROUND: Craniovertebral junction (CVJ) hydatid disease, although rare, forms an important differential diagnosis of CVJ bony pathologies, especially in endemic areas due to the sheer volume of cases presented there. The authors report a rare case of CVJ hydatid disease mimicking a bony expansile tumor on imaging. CASE DESCRIPTION: A 21-year-old woman presented with a left-sided neck tilt and pain for 3 months, intermittent low-grade fever, and features of high cervical myelopathy (Nurick grade II). Magnetic resonance imaging and computed tomography imaging showed a solid enhancing mass with numerous small cystic areas with bony erosion of the basiocciput, C1 and C2 vertebrae, suggestive of an expansile bony lesion (osteoblastoma/giant cell tumor/aneurysmal bone cyst). She underwent a posterior approach for decompression and spinal fixation, and multiple clear grape-like cysts were encountered that were confirmed to be hydatid cysts on histopathology. All visible cysts were excised and instrumented fusion of the CVJ performed. Albendazole was continued for 6 weeks and at 3 months' follow-up, the patient remains asymptomatic with no recurrence on imaging. CONCLUSIONS: The authors conclude that in tropical regions, hydatid disease of the cervical spine should be considered in the differential diagnosis of patients presenting with high cervical compressive myelopathy, especially when associated with fever. Spinal hydatosis may mimic a bony lesion on imaging and should be kept in mind, as in addition to routine decompression, use of scolicidal agents and intact removal of cysts have a significant effect on reducing the recurrence rate and improving the outcome.

Systematic review of the nonsurgical management of atlantoaxial rotatory fixation in childhood.

OBJECTIVE: Atlantoaxial rotatory fixation (AARF) is an acquired fixed abnormality of C1-2 joint rotation associated with torticollis in childhood. If the condition is left uncorrected, patients are at risk for developing C1-2 fusion with permanent limitation in the cervical range of movement, cosmetic deformity, and impact on quality of life. The management of AARF and the modality of nonsurgical treatment are poorly defined in both primary care and specialized care settings, and the optimal strategy is not clear. This systematic review aims to examine the available evidence to answer key questions relating to the nonsurgical management of AARF. METHODS: A systematic review was performed using the following databases: PubMed, MEDLINE, Healthcare Management Information Consortium (HMIC), EMCare, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), British Nursing Index (BNI), and Allied and Complementary Medicine Database (AMED). Search criteria were created and checked independently among the authors. All articles with a radiological diagnosis of AARF and primary outcome data that met the study inclusion criteria were included and analyzed by the authors. RESULTS: Search results did not yield any level I evidence such as a meta-analysis or randomized controlled trial. The initial search yielded 724 articles, 228 of which were screened following application of the core exclusion criteria. A total of 37 studies met the full criteria for inclusion in this review, consisting of 4 prospective studies and 33 retrospective case reviews. No articles directly compared outcomes between modalities of nonsurgical management. Six studies compared the outcome of AARF based on duration of symptoms before initiation of treatment. Comparative analysis of studies was hindered by the wide variety of treatment modalities described and the heterogeneity of outcome data. CONCLUSIONS: The authors did not identify any level I evidence comparing different nonsurgical management approaches for AARF. There were few prospective studies, and most studies were uncontrolled, nonrandomized case series. Favorable outcomes were often reported regardless of treatment methods, with early treatment of AARF tending to yield better outcomes independent of the treatment modality. There is a lack of high-quality data, and further research is required to determine the optimal nonsurgical treatment strategy.

Management of CVJ tuberculosis: the changing paradigm.

BACKGROUND: The literature seems fractured for the management of craniovertebral junction (CVJ)-tuberculosis (TB). Presently, non-surgical management has been in vogue for neurologically intact patients. On the contrary, severely disabled cases of CVJ-TB continue to attract discussion, tilted towards surgical intervention. We present our experience with the non-surgical management of CVJ-TB tailored to their neurological status. METHODS: Authors managed 37 cases (2004-2019; age 1-57 years, mean 36 years) of CVJ-TB, of which eighteen (18/37, 48.6%) were severely disabled (Nurick grade ≥ 3) with a mean follow-up of 84 months (48-192 months). Irrespective of the clinical status and radiological findings, all patients were managed on medical management only. Needle aspiration established pathology in 23 (62.2%) cases, while 9 (24.3%) cases required drainage of an abscess. All patients received 18 months of anti-tubercular therapy (ATT). In patients with Nurick grade ≥ 3 and documented AAD, we applied halo vest for 12 months to achieve cervical immobilization. Only hard cervical collar for 3 months was prescribed in patients with no documented AAD. RESULTS: All minimally disabled cases (Nurick grade ≤ 2, n = 19) responded favorably (n = 18) to ATT, except for an infant, who succumbed to irreversible hypoxic brain damage due to the obstructed aero-digestive gateway. Of the severely disabled cases (Nurick grade ≥ 3, n = 18), 16 cases had favorable outcomes with only external orthosis (12) and 18-month ATT. One patient succumbed to multiple cerebral infarcts, while one required realignment surgery at CVJ due to fusion in malaligned position. CONCLUSION: The authors conclude that the disability grading of CVJ-TB is pertinent only for assessing the functional disability of patients at presentation, with minimal relevance in deciding its management strategy. Irrespective of neurological disability, almost all patients respond favorably to external immobilization and ATT.

A case of acute calcium pyrophosphate arthritis in two rare sites of involvement: The cervical facet and atlantoaxial joint.

Calcium pyrophosphate dihydrate deposition (CPPD) disease, also known as pseudogout, in which crystals are deposited in the joints and/or soft tissues, leads to a variety of articular and periarticular disorders. Herein we report a 67-year-old female patient with neck pain who was diagnosed as CPPD disease of both the atlantoaxial joint and right C4-C5 facet joint with radiological findings. The combined use of computed tomography and magnetic resonance imaging can be helpful in establishing a diagnosis and providing the correct treatment.

Chiari malformation type I and basilar invagination originating from atlantoaxial instability: a literature review and critical analysis.

INTRODUCTION: Recently, a novel hypothesis has been proposed concerning the origin of craniovertebral junction (CVJ) abnormalities. Commonly found in patients with these entities, atlantoaxial instability has been suspected to cause both Chiari malformation type I and basilar invagination, which renders the tried and tested surgical decompression strategy ineffective. In turn, C1-2 fusion is proposed as a single solution for all CVJ abnormalities, and a revised definition of atlantoaxial instability sees patients both with and without radiographic evidence of instability undergo fusion, instead relying on the intraoperative assessment of the atlantoaxial joints to confirm instability. METHODS: The authors conducted a comprehensive narrative review of literature and evidence covering this recently emerged hypothesis. The proposed pathomechanisms are discussed and contextualized with published literature. CONCLUSION: The existing evidence is evaluated for supporting or opposing sole posterior C1-2 fusion in patients with CVJ abnormalities and compared with reported outcomes for conventional surgical strategies such as posterior fossa decompression, occipitocervical fusion, and anterior decompression. At present, there is insufficient evidence supporting the hypothesis of atlantoaxial instability being the common progenitor for CVJ abnormalities. Abolishing tried and tested surgical procedures in favor of a single universal approach would thus be unwarranted.

An Unusual Cause of Vertebrobasilar Insufficiency in a Case of Atlantoaxial Dislocation with Anomalous Vertebral Artery.

BACKGROUND: Posterior circulation stroke resulting from atlantoaxial dislocation (AAD), although uncommon, is a well-described entity. The normally coursed V3 segment of the vertebral artery (VA) is likely to be stretched because of C1-C2 dislocation and further compromised by the C1-C2 translational mobility. The persistent first intersegmental artery (PFIA), an anomalous variant does not course through the C1 transverse foramen, but rather crosses the posterior C1-C2 joints and is unlikely to be affected by the C1-C2 dislocation. Therefore, a patient with AAD and anomalous VA presenting with stroke should be evaluated for other etiologies of VA compromise. CASE DESCRIPTION: We report a patient of AAD with PFIA who presented with posterior circulation stroke. Careful radiological evaluation revealed a loose body (LB) adjacent to the medial aspect of the left C1-C2 facet compressing the anomalous VA. Intraoperatively, there was a large LB on the posteromedial border of the joint, compressing the VA. The anomalous VA was mobilized, and the offending element removed followed by fixation of the C1-C2. CONCLUSIONS: One should be aware of such an etiology of arterial compromise in cases of AAD with coexistent anomalous VA. An underlying LB or large osteophytes resulting from instability may be the offending cause, and needs to be dealt with, as fusion alone may not benefit the patient.