Augmented Reality Versus Freehand Spinopelvic Fixation in Spinal Deformity: A Case-Control Study

This study sought to compare screw placement accuracy and outcomes between freehand (FH) and AR-guided pelvic fixation. While pelvic fixation is a critical technique in spinal deformity surgery, S2-alar iliac (S2AI) screw placement poses challenges.

We conducted a case-control study of 50 consecutive patients who underwent spinopelvic fixation at a single institution. AR guidance was performed using a head-mounted display (Xvision, Augmedics). Patient demographics, surgical characteristics, spinopelvic parameters, and screw breach grade were compared using univariate and multivariate statistics.

Pelvic fixation was performed FH in 21 patients (median age, 64; female, 38.1%; median BMI 32.3 kg/m²) and AR-guided in 29 patients (median age, 66; female, 51.7%; median BMI 28.4 kg/m²). Mean follow-up was longer in the FH group (28 mos vs 11 mos, P < 0.001). Pelvic fixation in the FH group was performed using either S2AI (90.5%) or dual S2AI (9.5%) screws. There were no significant differences in length of surgery (FH, 439 minutes; AR, 490 minutes; P = 0.1) or estimated blood loss (FH, 2.1L; AR, 1.9L; P = 0.7). Accuracy of FH pelvic fixation was 95.6% (43/45 screws) and accuracy of AR pelvic fixation was 96.5% (55/57 screws). Multivariable logistic regression for screw breach revealed no significant association with AR guidance when controlling for age, BMI, osteoporosis, and smoking.

We present the first case-control study of AR-guided spinopelvic fixation, with findings suggesting parity between FH and AR-guidance, serving as foundation for prospective controlled studies with longitudinal follow-up to interrogate the benefits of AR-guidance in spinal deformity surgery.