[Surgical Therapy of Fixed Atlantoaxial Rotatory Dislocation - Monocentric Study of 15 Patients]

PURPOSE OF THE STUDY Atlantoaxial Rotatory Dislocation (AARD) mostly occurs in children and prevailing majority of cases are successfully managed by non-operative treatment. Surgical intervention is necessary in patients in whom non-operative treatment failed, in case of repeated dislocations and in patients with anatomical defects of the atlantoaxial complex. The purpose of the presented study is the radiological and clinical evaluation of patients with AARD surgically treated at our department. MATERIAL AND METHODS In the period from 2001 to 2017, altogether 15 patients with AARD were surgically treated at our department, namely 6 men and 9 women aged 5-72 years, with the mean age of 27.3 years. 8 patients were younger than 18 years of age. Apart from regular checks, all the patients were examined also at the end of the study, which means at a follow-up of 12-214 months, i.e. 112.1 months postoperatively on average. In the study, the anatomy of the atlantoaxial complex and craniocervical junction, course of the surgical procedure, correction of deformity, bone fusion, clinical condition of the patient and complications were monitored and evaluated. The clinical evaluation was performed using the Visual Analogue Scale (VAS) for neck pain and the Neck Disability Index (NDI). All the parameters were statistically evaluated at the p-level below 0.05. RESULTS In all 15 patients the surgery was preceded by unsuccessful non-operative treatment. The period between the rotation and the surgery was 4 days to 48 months, with the mean value of 11.3 months. All the patients included in the study showed an intact dens axis, the other patients were excluded from the study. In 10 patients their head was rotated to the left, in 5 patients to the right. The anterior atlantodental interval (ADI) was 2-7 mm with the mean value of 3.5 mm. In 13 cases the ADI was less than 5 mm, in 2 cases it was greater. According to the Fielding and Hawkins classification there were 9 cases of type I, 4 cases of type II and two cases of type III. According to the Ishii et al. classification, 2 cases of type I, 12 cases of type II and one case of type III were identified. In 9 patients predisposing factors were found in the history, namely 7 cases of trauma, 2 cases of infection. Mutual rotation of C1-C2 from 7.0° to 60.0° with the mean value of 27.3° was observed preoperatively, while after the correction it was from 1.0° to 7.0° with the mean value of 3.9° (p < 0.05). Lateral inclination was 3.4°-23.6° preoperatively with the mean value of 9.9°, and 0.7°-4.0° after the correction with the mean value of 2.2° (p < 0.05). The postoperative ADI ranged from 1 to 3 mm, with the mean value of 1.9 mm (p < 0.05). The bone fusion of C1-C2 or C1-C2-C3 was achieved in all the relevant cases (N = 13, 100%), in two patients a temporary fixation was used. The mean value of VAS for neck pain was 6.3 preoperatively, 1.0 (p < 0.05) at one year and 1.0 (p < 0.05) again at the final examination. The mean value of NDI was 50.4 % preoperatively, 9.3% (p < 0.05) at one year and 9.5% (p < 0.05) at the final examination. All patients that we operated on stated that they would undergo surgery again. DISCUSSION Compared to the other authors, our group of patients included surprisingly many adult patients (46.7%) with a high percentage of neurological defects (33.3%). In agreement with the literature, the cause of rotation was revealed in 60% of cases. At our department, correction is preferred in all the patients, while especially in paediatric patients in situ fixation causes the developmental deformities of the face and cervical spine. High success rate of bone fusion was confirmed (13/15, 13 = 100%) and also the transient atlantoaxial fixation was successfully used in two patients, both with traumatic etiology. CONCLUSIONS If non-operative treatment fails, surgical correction of AARD is a suitable treatment method which ensures favourable position of the atlantoaxial complex, improves the clinical condition of the patient and prevents the asymmetric development of the face in children. The Goel-Harm's fixation technique and C1-C2 fusion are considered by us the method of choice in older paediatric and adult patients. Key words: AARD, atlantoaxial rotatory dislocation, atlantoaxial rotatory subluxation, pediatric cervical spine, atlantoaxial fixation.