OBJECTIVE: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.
METHODS: Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution\'s imaging platform (PACS). Statistical significance was set at p < 0.05.
RESULTS: A total of 128 patients (51% female, age 62 [54-72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.
CONCLUSIONS: The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations.

Bone quality is increasingly being recognized in the assessment of fracture risk. Nonenzymatic collagen cross-linking with the accumulation of advanced glycation end products stiffens and embrittles collagen fibers thus increasing bone fragility. Echogenicity is an ultrasound (US) parameter that provides information regarding the skin collagen structure. We hypothesized that both skin and bone collagen degrade in parallel fashion. Prospectively collected data of 110 patients undergoing posterior lumbar fusion was analyzed. Preoperative skin US measurements were performed in the lumbar region to assess dermal thickness and echogenicity. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and analyzed with confocal fluorescence microscopy for fluorescent advanced glycation endproducts (fAGEs). Pearson\'s correlation was calculated to examine relationships between  (1) US and fAGEs, and (2) age and fAGEs stratified by sex. Multivariable linear regression analysis with adjustments for age, sex, body mass index (BMI), diabetes mellitus, and hemoglobin A1c (HbA1c) was used to investigate associations between US and fAGEs. One hundred and ten patients (51.9% female, 61.6 years, BMI 29.8 kg/m2 ) were included in the analysis. In the univariate analysis cortical and trabecular fAGEs decreased with age, but only in women (cortical: r = -0.32, p = 0.031; trabecular: r = -0.32; p = 0.031). After adjusting for age, sex, BMI, diabetes mellitus, and HbA1c, lower dermal (β = 1.01; p = 0.012) and subcutaneous (β = 1.01; p = 0.021) echogenicity increased with increasing cortical fAGEs and lower dermal echogenicity increased with increasing trabecular fAGEs (β = 1.01; p = 0.021). This is the first study demonstrating significant associations between skin US measurements and in vivo bone quality parameters in lumbar fusion patients. As a noninvasive assessment tool, skin US measurements might be incorporated into future practice to investigate bone quality in spine surgery patients.

OBJECTIVE: Previous studies have reported decreased dermal echogenicity and increased skin oxidative stress in overweight males. However, it is unknown whether these skin parameters of overweight and obese people are similar to those of individuals exhibiting a normal body weight following weight loss. The purpose of this study was to (1) compare the changes in the dermal structure parameters and levels of skin oxidative stress before and after weight loss in overweight and obese people in Japan and (2) to clarify how these aspects changed when body weight would be reduced to normal body weight.
METHODS: Male volunteers with a body mass index of ≥25 kg/m2 were recruited. The dermal structure was visualized and dermal echogenicity and thickness were measured using ultrasound scanners. The mRNA expression level of heme oxygenase-1 in the hair follicles was quantitatively analyzed as a marker of skin oxidative stress.
RESULTS: When overweight individuals in their 20s to 30s reduced their weight to normal, decreased dermal thickness in the abdominal region was observed in 50% of the subjects; however, no increase in dermal echogenicity was observed. A decrease in dermal thickness and an increase in dermal echogenicity in the thighs was observed in 83.3% of the subjects. No decrease in the level of dermal oxidative stress was observed.
CONCLUSIONS: The dermal structure in the thighs of overweight young individuals can be improved to the level of the structure in those of normal body weight individuals following weight loss.

OBJECTIVE: Skin atrophy is one of the main side effects of long-term topical corticosteroid therapy. It has already been studied through ultrasound skin-thickness measurement. In this study, the quantification of dermal echogenicity was introduced to provide new information on this phenomenon.
METHODS: Skin thinning induced by topical application (without occlusion) of the superpotent corticosteroid clobetasol propionate (0.05% lotion), was assessed by means of ultrasonography in terms of thickness and echogenicity. 15 healthy volunteers were treated for 6 weeks, 1 daily, 5 days a week on the forearms.
RESULTS: The thinning showed a biphasic pattern, with a 1st period of rapid change (about 15% of thinning in a week) followed by a period of slower but significant change. Skin thickness returned to baseline values 3 weeks after the end of treatment. Dermal echogenicity, which represents the mean intensity of the ultrasound signals reflected by the dermis, was found to follow the same variations, increasing strongly during the 1st week, then more slowly. The 2 parameters are correlated and probably reflect the same physiological modifications responsible for skin thinning, i.e., a reduction in glycosaminoglycan synthesis (leading to a drastic fall in dermal water content) and vasoconstriction.
CONCLUSIONS: This sensitive and non invasive method enables us to identify the effects of clobetasol propionate on the healthy dermis in the absence of any clinical signs of thinning.