Directed acoustic shadow enhancement for pre-incision ultrasound localization and precise incision planning in...

Accurate pre-incision localization of fracture segments is essential for targeted exposure during surgical stabilization of rib fractures (SSRF). We evaluated Directed Acoustic Shadow Enhancement (DASE), a simple ultrasound-assisted localization technique using an external cotton swab as an acoustic reference marker to translate sonographic fracture findings into skin surface marking.

This single-center retrospective comparative study included 91 adult patients with multiple (≥3) rib fractures who underwent SSRF, including 22 consecutive DASE-assisted cases and 69 historical controls treated using conventional preoperative localization. Both groups received the same intermuscular approach and nitinol memory alloy encircling fixation, with the principal difference being the pre-incision localization strategy. The primary outcomes were skin-to-skin operative time and incision length per plated rib. Secondary outcomes included blood loss, prophylactic intraoperative chest tube placement, postoperative day 3 visual analog scale (VAS) pain score, and length of stay. Atelectasis and pulmonary infection were analyzed as trauma-related preoperative thoracic complications rather than postoperative outcome events. The primary analytic framework consisted of full-cohort comparison and multivariable regression.

All 22 DASE cases achieved successful pre-incision localization without localization-related complications or conversion to conventional localization. Compared with historical controls, the DASE group had shorter operative time (78.5 ± 31.9 vs. 102.8 ± 31.9 min; p = 0.004), shorter total incision length (8.0 ± 3.0 vs. 10.7 ± 3.7 cm; p = 0.001), and shorter incision length per plated rib (2.53 ± 1.02 vs. 3.20 ± 1.25 cm/rib; p = 0.016). In multivariable regression, DASE remained associated with shorter operative time (adjusted β, -20.64 min; 95% CI, -37.75 to -3.52; p = 0.018), shorter incision length per plated rib (adjusted β, -0.70 cm/rib; 95% CI, -1.28 to -0.12; p = 0.018), and lower blood loss (adjusted β, -61.13 mL; 95% CI, -107.65 to -14.60; p = 0.010), although blood loss was interpreted cautiously. Case-sequential localization time in the DASE cohort showed a significant downward trend, suggesting a descriptive pattern consistent with an early learning phase.

DASE appears to be a feasible and safe pre-incision ultrasound-assisted localization adjunct for SSRF. This technique may support more targeted exposure and operative planning; however, these findings should be interpreted cautiously and require confirmation in larger prospective studies.