C1 lateral mass reduction screws for treating atlantoaxial dislocations: Bringing ease by modification

Area of Science:

• Neurosurgery
• Orthopedic Surgery
• Spinal Surgery

Background:

• Craniovertebral junction (CVJ) anomalies present complex management challenges.
• Current C1-C2 fixation techniques using polyaxial screws can lead to technical difficulties in rod fitting and reduction.
• Forceful joint handling is often required, increasing the risk of neurological injury.

Purpose of the Study:

• To evaluate the efficacy of a specialized "reduction screw" in C1 lateral mass for C1-C2 fixation.
• To assess the use of this screw in treating atlantoaxial dislocations (AAD) with or without basilar invagination (BI).

Main Methods:

• Retrospective cohort study involving 18 patients with congenital AAD and/or BI.
• C1-C2 fixation was performed using long lateral mass reduction screws in the C1 vertebra.
• Clinical outcomes were assessed using the modified Japanese Orthopedic Association score; radiological outcomes were evaluated using craniometric indices.

Main Results:

• The study included 18 patients (72% male, average age 33.5 years) with AAD and BI (84%), Chiari Type 1 malformation (22%), or Klipple-Feil syndrome (one patient).
• All patients experienced symptomatic improvement post-surgery.
• Complete reduction of AAD and normalization of radiological indices were achieved in 100% of patients.

Conclusions:

• The C1 lateral mass reduction screw facilitates effective reduction of AAD and BI (Type A) in complex CVJ anomalies.
• This technique offers intraoperative ease, reduces operative time, and avoids the need for special instruments or complex maneuvers.
• The use of the reduction screw minimizes the risk of neurological injury during C1-C2 fixation.