European Spine Journal (2018) 27:1342–1348
Feasibility and outcome of stand‑alone trans‑articular screw xation
in atlantoaxial instability in children less than 8 years of age
· Vishal Kundnani
· Tarun Dusad
· Ankit Patel
Received: 12 February 2017 / Revised: 2 January 2018 / Accepted: 2 February 2018 / Published online: 12 February 2018
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
Purpose To study the feasibility and outcome of stand-alone trans-articular screw (TAS) ﬁxation for atlantoaxial instability
(AAI) in children less than 8 years of age.
Methods This prospective study was conducted between 2009 and 2014. Thirteen children suﬀering from AAI were oper-
ated for a TAS ﬁxation. Feasibility of TAS ﬁxation was assessed on CT scan and a screw diameter was chosen based on C2
isthmus diameter. Demographic data collected included the etiology for AAI, age, and sex. Intra-operative data recorded
was the duration of surgery, blood loss, vertebral artery injury or any adverse event. Radiological evaluation included pre-
and post-operative atlantodens interval (ADI) and space available for cord (SAC) and fusion was evaluated at 3, 6, 12 and
24 months. Statistical analysis was done using SPSS software and statistical signiﬁcance was set at p < 0.05.
Results The mean age of the ﬁnal study group was 6.1 ± 1.5 years, with nine males and four females. Mean isthmus diameter
on the left and right side was 3.3 ± 0.3 and 3.2 ± 0.2 mm, respectively. Five patients had an isthmus diameter of < 3.2 mm
and a 2.7 mm Herbert screw was used in them and in nine patients, a CCS of 3.2 mm was used. Mean pre- and post-op ADI
and SAC improved from 5.5 ± 0.8 to 3.1 ± 0.1 mm, respectively, and 9.8 ± 2.8 to 14 ± 0.6 mm, respectively. Fusion was
seen in all patients.
Conclusions Stand-alone TAS with morselized allograft is safe, feasible and successful in managing AAI in children below
8 years of age.
Graphical abstract These slides can be retrieved under Electronic Supplementary Material.
[Paediatric, TAS, allograft, Atlanto-axial Instabiliy, Cervical Spine,
1. TAS diameter should be choosenin accordance with the C2
isthmus diameterto improvesafetyand feasibility of the
2. The TAS should pass through the dorsal and medial most aspect of
the C2 pars-pedicle junction to reduce chances of a vertebral artery
3. Excellent results can be obtained despite omitting the posterior
[Demographic, radiological and operative data of the study group.][Demographic, radiological and operative data of the study group.]
33.2 2.7/2.7no60120 no no yes
2 5 Tuberculosis3.6 3.53.2/3.2 no 90 170nonoyes
3 5Downs332.7/2.7 no 50 150nononoyes
4 6Os Odontoid 3.64 3.2/3.2no8080nonoyes
5 7Trauma3.5 3.43.2/3.2 no 11090nonoyes
6 4Trauma2.9 32.7/2.7 no 16090nonoyes
7 7Trauma3.4 3.63.2/3.2 no 90 110nonoyes
8 7Rotatory Instability
32.8 2.7/2.7no140 120nonoyes
9 8Rotatory Instability 332.7/2.7no70110 no no yes
10 6Downs Syndrome 3.32.5 3.2/Xyes 90 160nosoŌ collar
11 8Os Odontoid3.5 3.33.2/3.2 no 13090nonoyes
Rotatory Instability 43.5 3.2/3.2no80100 no no yes
13 5Juvenile Rheumatoid
3.43.5 3.2/3.2no80110 no no no yes
Take Home Messages
1. Screw diameter for TAS fixation should be determined based on the
diameter of the isthmus of the Axis.
2. Smaller diameter screws(2.7mm and 3.2mm) are a viable implant
choice in children with AAI.
3. Fusion rates of 100% wereobserved using morsellizedallograft.
Keywords Pediatric · TAS · Allograft · Atlantoaxial instability · Cervical spine · Fusion rates
The management of atlantoaxial instability (AAI) in chil-
dren is fraught with many challenges. Various modalities
of ﬁxation for AAI (trans-articular screw ﬁxation, C1–C2
segmental ﬁxation) are reported to have excellent outcomes
in adults [1–3]. However, many of these techniques are not
Electronic supplementary material The online version of this
article (https ://doi.org/10.1007/s0058 6-018-5510-7) contains
supplementary material, which is available to authorized users.
* Shumayou Dutta
Extended author information available on the last page of the article