Ultrasound-Guided Emulsification Therapy in the Clinical Treatment of Subcutaneous Lipomas

New Technology: The Cavitron Ultrasonic Surgical Aspirator (CUSA) is an emerging minimally invasive technique that utilizes high-frequency ultrasonic vibration to fragment tissue, with simultaneous saline irrigation for emulsification and immediate aspiration. Compared with conventional open excision and simple liposuction, CUSA offers the advantages of high tissue selectivity, minimal damage to surrounding blood vessels and nerves, effective fragmentation and clearance of fibrotic components, good intraoperative hemostasis, a clear operative field, the ability to operate through a small incision, rapid postoperative recovery, and inconspicuous scarring. However, its clinical safety and efficacy in the minimally invasive resection of lipomas, particularly those with abundant fibrotic components, remain to be systematically validated.

Sample Size Calculation (30 cases): This is a single-center, prospective, single-arm clinical study with the primary outcome of tumor clearance rate after CUSA minimally invasive resection of lipomas. According to previous literature, the complete clearance rate of conventional open excision is approximately 95%, while simple liposuction achieves a clearance rate of 70%-80% for fibrotic lipomas. This study assumes that the tumor clearance rate of CUSA minimally invasive treatment is no less than 90%. With a two-sided significance level α = 0.05 and a margin of error d = 10%, the sample size is calculated using the binomial distribution formula:

n = Z²α/2 × p(1-p) / d² Substituting p = 0.90, Zα/2 = 1.96, and d = 0.10 yields n ≈ 34.6. Accounting for an approximate 10% loss to follow-up, a total of 30 patients will be enrolled. In addition, as an exploratory study, a sample size of 30 is sufficient to assess the safety and preliminary efficacy of the CUSA technique and is comparable to the sample sizes of similar studies (20-40 cases) reported in the literature.

Statistical Analysis Methods:Analysis sets: The full analysis set (FAS), including all patients who received CUSA treatment and completed at least one postoperative assessment, will be used for efficacy analysis. The safety set (SS), including all patients who received CUSA treatment, will be used for safety analysis.

Descriptive statistics: Normally distributed continuous variables are presented as mean ± standard deviation (x̄ ± s); non-normally distributed continuous variables are presented as median (interquartile range) [M (P25, P75)]; categorical variables are presented as frequency (percentage) [n (%)].

Primary outcome analysis: The tumor clearance rate is presented as a point estimate with a 95% confidence interval (95% CI), calculated using the binomial distribution method.

Secondary outcome analysis: Continuous variables such as operation time, intraoperative blood loss, and postoperative pain score (VAS) are analyzed using descriptive statistics; categorical variables such as complication rate and recurrence rate are presented as frequency (percentage) with 95% CI.

Survival analysis: The postoperative recurrence-free survival rate is analyzed using the Kaplan-Meier method, and survival curves are plotted.

Statistical software and significance level: Statistical analysis is performed using SPSS 26.0 (IBM Corp., Armonk, NY, USA) or R 4.x software. All tests are two-sided, and P < 0.05 is considered statistically significant.