P50. T1 tilt and clavicle angle are the best predictors of postoperative shoulder and neck balance in AIS patients

Abstract

<h3>BACKGROUND CONTEXT</h3> Shoulder imbalance after PSF is a major concern. Most studies have analyzed multiple radiographic parameters associated with postop uneven shoulders. However, there is paucity in the literature analyzing predictors for balanced shoulders. <h3>PURPOSE</h3> Shoulder imbalance after PSF is a major concern. Most studies have analyzed multiple radiographic parameters associated with postop uneven shoulders. However, there is paucity in the literature analyzing predictors for balanced shoulders. <h3>STUDY DESIGN/SETTING</h3> Retrospective review. <h3>PATIENT SAMPLE</h3> AIS patients who underwent PSF from 2012 to 2020 were included in this study. <h3>OUTCOME MEASURES</h3> Radiographic shoulder height, median shoulder height, T1 tilt, clavicle angle, first rib angle and cobb angle. <h3>METHODS</h3> Radiographic shoulder height (RSH) was used as our proxy for shoulder height. RSH. <h3>RESULTS</h3> Part I: 211 control patients were evaluated. 191 had normal RSH and 20 were abnormal. T1 tilt (2.0 vs 4.1) and CA (1.1 vs 4.95) were significantly different between the two groups (p < .05). Part II: In 186 patients, preoperative and postoperative CA correlated very strongly with RSH (r = 0.856/0.921). T1 tilt correlated moderately with RSH (r = 0.399), but was better when concordant (r = 0.51). RSH did not change significantly from immediate postop to final follow up (p=0.423). Restoring CA below 3 degrees yielded normal RSH postop (p < 0.0001). Restoring Concordant T1 tilt below 3 degrees yielded normal RSH in nearly all cases (p < 0.006). Part III: In 59 patients across 4 surgeons, restoring CA below 3 degrees yielded normal RSH at postop in all cases. Restoring concordant T1 tilt below 3 degrees yielded normal RSH at postop in nearly all cases. <h3>CONCLUSIONS</h3> Restoring shoulder balance in AIS patients is a challenging aspect of surgery. We found that restoring the CA < 3° yields normal RSH postoperatively. In addition, when T1 is concordant, restoring it to < 3 degrees can yield normal RSH. Proximal thoracic fusion did not correlate with post op RSH. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.