2026 Poster Presentations
P072: FREE HAND C1-C2 SCREW PLACEMENT IN CV JUNCTION ANOMALY: DOES ANATOMICAL COMPLEXITY MATTER?"
Pawan Kumar Verma, Dr; Sanjay Gandhi Post Graduate Institute Of Medical sciences, Lucknow, India
Background:
Conventionally, C1-C2 fixation is being performed with the help of intra-operative C-arm and navigation systems etc. However, these modalities have been associated with high operating cost, increased operative time and radiation exposure to both the patient and healthcare personnel. Unlike other areas of spine, CV junction region harbors many anatomical landmarks which are really helpful for free hand screw placement. Here Author want to highlights the merits of free hand screw placement based on anatomical landmarks.
Aims and Objectives:
To evaluate the accuracy of C1 C2 screws placement by free hand technique in craniovertebral junction anomalies
To evaluate the intraoperative anatomical complexity and screws malposition association
Material and Methods: We retrospectively reviewed and evaluated C1 Transpedicular, C1 lateral mass, C2 pars and C2 pedicle screws on post-operative CT scan of all patients who has undergone for posterior fixation in last 6 years. The patients of acute trauma of CVJ and purely sub-axial instrumentation were excluded (owing to their normal anatomical landmarks). The patient’s demographic details, clinical details, radiological details, major intraoperative events and post-operative complications were also noted. We divided the whole patient in two groups, simple CVJ group (mobile or fixed atlantoaxial dislocation with symmetrical C1-C2 joints with normal course of vertebral arteries) and complex CVJ group (atlantoaxial dislocations with basilar invagination with or without platybasia) based in their anatomical characteristic on the preoperative dynamic computed tomography (CT) scan with CT angiography of CVJ region. The screws Malposition grades and direction were defined as per Hojo grading scale. The trajectory of malposition was further classified into medial, lateral, superior and inferior.
Results: Total 221 patients were included in the study. The mean age of presentation was 27.84 years. The major symptoms were spastic quadriparesis, restricted neck movements, sensory symptoms, LCN involvement, and autonomic involvement. On radiological evaluation 63(28.5%) patients were in simple CVJ anomaly group while 158 (71.5%) patients were in complex CVJ anomaly group. The accuracy of screws placement by freehand technique was 84.42%. In simple group total 220 C1-C2 screws were placed with 83.64% in grade 0 (correct placement). In complex CVJ group total 486 C1, C2 screws were placed with 84.77% in grade 0. Overall malposition rate was 15.58%. The rate of misplacement of screws in simple (16.36%) and complex (15.23%) groups were almost comparable (p value- 0.7007). The majority belongs to Grade-1(12.45%) followed by grade 2 in 2.83%. The most common malposition trajectory was medial (34.75%) followed by inferiorly (28.5 %).
Conclusions: The rate of accurate screw placement by free hand technique without use of fluoroscopic or neuro-navigation guidance is comparable to the large studies published in literature. This practice can significantly cut down the fluoroscopy hazards to both the patient and health care personnel. The study also highlights that anatomical complexity is no more contraindication for free hand technique and breaks the barrier of false perception about high rate of malposition in complex CVJ anomaly cases.