Retrospective radiographic study of Occipito-atlantal joint for the patients with chronic atlanto-axial rotatory fixation or dislocation

English Keywords:Atlantoaxial  Rotatory fixation  Rotatory subluxation  Grisel′s syndrome  Occipitoatlantal dislocation

English Abstract:

  【Abstract】 Objectives: To investigate the radiographic changes of the occipito-atlantal joint for the patients with chronic atlanto-axial rotatory fixation or dislocation(AARF/D) before and after our treatment. Methods: A series of 40 cases were diagnosed and treated in our hospital from September 2004 to June 2019, including 19 males and 21 females, with the mean age of 11.2±2.8 years. The mean duration of symptoms was 6.0±5.7months(2-36 months), and the mean follow-up period was 5.7±3.1 months(3-18 months). According to author′s classification, there were three types of radiographic characteristic findings on the X ray films and CT scan: the first was atlantoaxial rotatory fixation(AARF); the second was atlantoaxial rotatory dislocation(AARD); the third was occipito-atlanto-axial rotatory dislocation(OAARD). There were 3 cases with type A(AARF); 36 cases with type B(AARD), among that, 10 cases with type B1, 21 cases with type B2, and 5 cases with type B3; and 1 cases with type C(OAARFD). One case with type A was reduced by traction and the other 2 cases with type A were reduced by skull traction and surgical atlantoaxial fusion under Halovest stablization. 36 cases with type B and one case with type C were treated by surgical atlantoaxial reduction and fusion. The imaging changes of the occipito-atlantal joint on CT scan before and after treatment were observed. Results: The occipito-atlantal rotatory displacement occurred in most cases with AARF/D before treatment and reduced after treatment. Spontaneous bony fusion took place in a few cases either before or after treatment. Before the treatment, except 1 case with type A and 3 cases with type B1 and 5 cases with type B3, occipito-atlantal rotatory displacement took place among all other cases in different size, 1 case with type C was occipito-atlantal dislocation. The occipito-atlantal joint developed to spontaneous bony fusion before our treatment in 2 case(1 case was with type B1 and 1 case with type B3). After the treatment, (1)the occipitoatlantal joint was normal in 22 cases(including 3 cases with type A, 19 cases with type B); (2)the joint developed to spontaneous bony fusion in 8 cases(including 6 cases with type B2,1 case with type B1 and 1 case with type B3); (3)the joint was partially reduced in 4 cases (including 3 cases with type B2 and 1 case with type C); (4)the joint space became narrow and indistinct in 4 cases (including 2 cases with type B1 and 2 cases with type B2). Conclusions: For most cases with type A and type B1 and all cases with type B2, the occipitoatlantal rotatory displacement occurred, and a few cases with type B developed spontaneous bony fusion before treatment. After treatment, the occipito-atlantal rotatory displacement reduced to normal alignment for all cases with type A and type B1, but in nearly half of cases with type B, occipito-atlantal joint developed to failed reduction and the joint space narrowed even spontaneous bony fusion developed after atlantoaxial rotatory alignment was reduced. One case with type C had left occipito-atlantal rotated displacement.