Vertebral Artery Variations at the Craniovertebral Junction in “Sandwich” Atlantoaxial Dislocation Patients

Objective: To summarize the vertebral artery (VA) pattern of 96 “sandwich” atlantoaxial dislocation (AAD) patients and to describe the strategies of reducing the injury of VA during surgery.Methods: From 2009 to 2020, we retrospectively reviewed the 3-dimensional computed tomography angiography data of 96 AAD patients combined with atlas occipitalization and C2–3 fusion, which were diagnosed as “sandwich” AAD and 96 patients as control group patients who were without atlas occipitalization, C2–3 fusion and any other cervical bone deformity at our institution. The variations of each side of VA were described in 3 different parts (C0–1, C1–2, and C2–3) according to the characteristics of the 3-part pathological structures in “sandwich” subgroup.Results: One hundred ninety-two sides of VAs in every group of patients were analyzed and every VA was described separately at 3 different level regions. There were different variations in these 3 different regions: 4 variations in the upper fusion region, 5 variations in the sandwiched region, and 6 variations in the lower fusion region in sandwich AAD patients. And the rate of VA deformity in sandwich AAD patients was much higher and more types of VA variations existed.Conclusion: In “sandwich” AAD patients, deformities of vertebral arteries in craniovertebral junction are more common, and the same VA may have deformities at different levels that severely affect surgical procedures. Therefore, preoperative imaging examination of VA for “sandwich” AAD patients is vital of guiding surgeons to avoid injury of VA during surgery.

Three-dimensional reduction method with a modified C2 isthmus screw in irreducible atlantoaxial dislocation: a technical note

Background Three-dimensional reduction plays a vital role in surgical reduction of irreversible atlantoaxial dislocation (IAAD). However, the most commonly used combination of C1 pedicle screw (PS) or lateral mass screw (LMS) and C2 PS or isthmus screw often fails to achieve satisfactory reduction at one time. The difficulty is usually caused by short anteroposterior and vertical distance between heads of C1 and C2 screws, which lack enough space for reduction operation. The objective of this study is to describe a three-dimensional reduction method with a modified C2 isthmus screw and to illustrate its advantage and effectiveness for IAAD. Methods Twelve patients with IAAD underwent reduction and fixation with modified C2 isthmus screw combined with C1 PS or LMS, fusion with autologous bone graft. The insertion point was lateral to the intersection of caudal edge of C2 lamina and lateral mass, with a trajectory towards C2 isthmus, via lateral mass. The three-dimensional reduction was achieved through pulling and distracting. Radiographic evaluation included anteroposterior and direct distance between different insertion points, the occipitoaxial angle (O-C2A), clivus-canal angle (CCA) and cervicomedullary angle (CMA). Clinical outcomes evaluation included the Japanese Orthopaedic Association (JOA) score, Visual analog scale (VAS) and Neck Disability Index (NDI). Results All the patients maintained effective reduction during the follow-up. The anteroposterior and direct distance was significantly higher in modified C2 isthmus screw than C2 PS whether combined with C1 PS or LMS (P < 0.05). The degree of O-C2A, CCA and CMA, JOA score, NDI, and VAS were significantly improved after the surgery (P < 0.05). Conclusions Three-dimensional reduction method with a modified C2 isthmus screw is effective and safe in managing IAAD. It can increase the anteroposterior and vertical distance between the heads of C1 and C2 screws, which is benefit for the three-dimensional reduction operation of IAAD.

Pharyngeal perforation: A rare complication of occipitocervical injury

Background: Atlantoaxial dislocation is a rare injury following high-energy trauma. We report an undescribed complication of atlantoaxial dislocation. Case Description: A 75-year-old man presented with atlantoaxial dislocation and Jefferson C1 fracture after a high-energy trauma. Occipitoaxial stabilizations were performed the day after. A nasopharyngeal fistula was identified at day 5 causing a persistent epistaxis. Conclusion: Nasopharyngeal fistulization of C1 bony fragment is a rare complication of complex occipitocervical injury. Combined treatment with ENT surgeon should be considered.

An unusual injury mechanism of atlantoaxial dislocation: illustrative case

BACKGROUND Atlantoaxial dislocation (AAD) is a rare and potentially life-threatening condition. Various underlying mechanisms of injury are described in the literature. Here, the authors report an unusual nontraumatic injury mechanism of AAD in a 12-year-old patient. OBSERVATIONS A 12-year-old boy presented with intolerable neck pain and numbness in both upper limbs. The patient’s symptoms had started 2 months after the initiation of online classes during the coronavirus disease 2019 pandemic without a history of trauma. He used a computer for personal study and online classes for prolonged hours with no respite. On physical and radiological evaluation, he was diagnosed with AAD. Before surgery, skull traction was applied to reduce the dislocation and posterior C1 lateral mass screw and C2 pedicle screw fixation was performed. An optimal clinical outcome was achieved with no postoperative complications. A preoperative visual analog scale score of 8.0 was reduced to 0 postoperatively. LESSONS A prolonged fixed neck posture is an unusual underlying cause of AAD. Posterior C1 lateral mass and C2 pedicle screw fixation results in an optimal clinical outcome.

Basilar Invagination: Surgical Treatment by Novel Anterior Implant

Introduction: Anterior retropharyngeal realignment, distraction, and atlantoaxial fixation are an option for the treatment of symptomatic basilar invagination (BI). The anterior implants for distraction and fixation for atlantoaxial joints are still evolving. We share our experience using a novel implant which can easily, safely, and rigidly fix both lateral masses to the body of the axis. Methods: After exposing both the atlantoaxial joints anteriorly, the joints were prepared, distracted with wedge shaped autologous tricorticate bone grafts and realigned to correct the cervicomedullary strain. The atlantoaxial joints were fixed using a novel titanium plate by passing screws upwards and laterally into the lateral masses of the atlas and centrally into the body of the axis. Post-operative imaging showed effective correction of BI and atlantoaxial dislocation. Post-operative dynamic X-ray images confirmed maintenance of rigid fixation at 6 months. Conclusion: This new plate screw construct is safe, easy, cost-efficient, and biomechanically appealing option for the treatment of symptomatic BI. Keywords: Basilar invagination, atlantoaxial dislocation, vertebral artery injury, atlantoaxial fixation, atlantoaxial instability.

AB0150 ACPA-STATUS AND RHEUMATOID ARTHRITIS: MUCH MORE TO BE REVEALED!

Background:Anti-citrullinated protein antibodies (ACPA) are commonly associated with Rheumatoid arthritis (RA). RA is, therefore, classified as immunopositive or immunonegative, with disparate mechanisms in predisposition.Objectives:Our study aimed to determine the baseline characteristics and differences of ACPA-positive and ACPA-negative RA.Methods:We conducted a cross-sectional study including 224 patients with RA. All patients fulfilled the 2010 American College of Rheumatology/European League Against Rheumatism RA classification criteria. The patients were divided according to their ACPA status into two groups: ACPA-positive group (G1) and ACPA-negative group (G2). We compared clinical, radiological, and laboratory findings between the two groups, as well as extra-articular manifestations, comorbidities including fractures and osteoporosis. The Fracture Risk Assessment Tool (FRAX) was used to estimate the 10-year probability of major osteoporotic fracture (MOF) and also hip fracture (FH).Results:Of the 224 patients, 31.6% were negative for ACPA (n=71). Female predominance was found in both groups with a sex ratio of 0.25 (p=0.203). ACPA-negative subjects were younger (57±11 versus 59±12 years) (p= 0.305).The initial presentation of RA was different between the two groups without reaching statistical significance. In the ACPA-negative group, alteration of general condition was more frequent (16.9% in G2 versus 13.7% in G1) (p=0.533), with a tendency to oligo-articular onset (18.5% in G2 versus 6.7% in G1) (p=0.737). ACPA-positivity was more associated with an acute start of symptoms (10.4% in G1 versus 8.4% in G2) (p=0.639)There was no significant difference in the mean DAS28-VS (5.2±1.1 in G2 versus 5.5±1.3 in G1) and DAS28-CRP levels (5±1 in G2 versus 5.3±1.2 in G1) (p=0.069 and p=0.098 respectively).ACPA-positive RA was, however, significantly associated with more structural joint damage: erosions (55.9±53 in G1 versus 78±36 in G2, p=0.01), joint space narrowing (50.4±45.5 in G1 versus 33.1±36.6 in G2, p=0.003), Sharp/van der Heijde radiographic score (126.6 ±103.2 in G1 versus 88.8±81.5 in G2, p=0.004). ACPA-positive RA patients had more atlantoaxial dislocation: 20.2% in G1 versus 7% in G2 (p=0.012). There was no significant difference in hip involvement (9.8% in G1 versus 14% G2) (p=0.344).There were no significant differences in extra-articular manifestations between the two groups: Rheumatoid nodules (10.4% in G1 versus 18.3% in G2) (p=0.891), Sjögren’s syndrome (16.3% in G1 versus 16.9% in G2)(p=0.715), amyloidosis (0.6% in G1) (p=1), pulmonary fibrosis (5.8% in G1 versus 4.2% in G2) (p=0.757), neurological signs (4.5% in in G1 versus 5.6% in G2) (p=0.733), anaemia (5.8% in G1 versus 1.4% in G2) (p=0.175).When analyzing comorbidities, no significant differences were found: diabetes (10.4% in G1 versus 18.3% in G2) (p=0.103), cardiovascular diseases (19.6% in G1) (p=1), neurological diseases (0.06% in G1 versus 1.4% in G2) (p=0.534), dysthyroidism (2.6% in G1 versus 5.6% in G2) (p=0.267), dyslipidemia (3.2% in G1 versus 4.2% in G2) (p=0.711), cancer (1.3% in G1) (p=1). There were neither significant differences in the prevalence of fracture (21.5% in G1 versus 18.3% in G2) (p=0.574), and osteoporosis (23.6% in G1 versus 29.5% in G2) (p=0.347), between the two groups. However, ACPA-positive patients presented with a significantly higher FRAX score of MOF (2±2.8 in G1 versus 1.2±1 in G2) (p=0.006), and FRAX score of FH (0,9±1.8 in G1 versus 0.3±0.5 in G2) (p=0.003).Conclusion:ACPA status appears to influence both the clinical presentation and radiological progression of RA patients. ACPA-positive patients present with an acute start of symptoms, with more structural damages and atlantoaxial dislocation. Comorbidities, including osteoporosis, does not seem affected by ACPA status. However, regardless of osteoporosis, ACPA-positivity is associated with a higher probability of major osteoporotic and hip fractures. Further research is needed to clarify this relationship.Disclosure of Interests:None declared