Use of a Smartphone Leveling Application to Optimize Cervical Thoracic Alignment Before Posterior Instrumentation

Abstract

Posterior cervical decompression and instrumentation (PCDI) often is associated with increase in sagittal balance and loss of lordosis. Here, we propose a simple method of surgical positioning using a readily available smartphone application to optimize cervical thoracic alignment in PCDI. The intent of this optimization is to minimize losses in lordosis and increases in sagittal balance. For patients since 2019, the position of the head was adjusted so that the occiput to thoracic spine was aligned and the chin brow angle was parallel to the rails of the surgical table using a leveling smart application (RIDGID level). Patients before 2019 who were not optimized were compared. There were 13 patients in the nonoptimized cohort (NOC) and 20 in the optimized cohort (OC). In the NOC, the change in lordosis was -7° (P= 0.016) and change in C2-sagittal vertical axis was 7 mm (P < 0.001) from preoperative to postoperative values. In the OC, the change in lordosis was 2° (P= 0.104) and change in C2-SVA was 2 mm (P= 0.592) from preoperative to postoperative values. Between the NOC and OC cohorts, the changes in lordosis and sagittal balance between cohorts were significant (P= 0.002 and P= 0.001, respectively). There was no significant difference in clinical outcomes as measured by Japanese Orthopaedic Association or complication rates. Positioning of the patient in preparation for PCDI can influence postoperative lordosis and sagittal balance. Using the leveling application on the smartphone (RIDGID level), is a rapid and free alternative for the maintenance of lordosis and sagittal balance during instrumentation in the operating room.