A Histological Assessment Tool for Breast Implant Capsules Validated in 480 Patients with and Without Capsular Contracture.

BACKGROUND: Understanding the impact of breast implants on the histological response in the surrounding fibrous capsule is important; however, consensus is lacking on how to analyze implant capsules histologically. We aimed to develop a standardized histological assessment tool to be used in research potentially improving diagnostic accuracy and treatment strategies for capsular contracture. METHODS: Biopsies of breast implant capsules from 480 patients who had undergone breast augmentation or reconstruction were collected and stained with hematoxylin and eosin. Initially, biopsies from 100 patients were analyzed to select histological parameters demonstrating the highest relevance and reproducibility. Then, biopsies from the remaining 380 patients were used to determine intra- and interobserver agreements of two blinded observers and agreement with a pathologist. Finally, we tested the association between the parameters and capsular contracture. RESULTS: The histological assessment tool included ten parameters assessing the inflammatory, fibrotic, and foreign-body reaction to breast implants, each graded on two-, three-, or four-point scales. Intra- and interobserver agreements were almost perfect (0.83 and 0.80), and agreement with the pathologist was substantial (0.67). Four parameters were significantly correlated with capsular contracture, namely chronic inflammation with lymphocyte infiltration (p < 0.01), thickness of the collagen layer (p < 0.0001), fiber organization (p < 0.01), and calcification (p < 0.001). CONCLUSIONS: This is the first validated histological assessment tool for breast implant capsules. The validated tool not only advances our understanding of capsular contracture but also sets a new standard for histological evaluation in breast implant research and clinical diagnostics. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The Prevalence and Histological Characteristics of the Double Capsule Phenomenon in Breast Augmentation With Implants.

BACKGROUND: Double capsule formation around breast implants is associated with implant rotation and seroma. However, the prevalence and histological characteristics remain unclear. OBJECTIVES: To quantify the prevalence of double capsule formation between different implant surface textures and to explore the histological differences between the inner- and outer capsules from breast implant capsule biopsies. METHODS: The study was performed on data from the Copenhagen Breast Implant (COBI) Biobank comparing the prevalence of double capsule formation around Allergan Biocell implants (Allergan, Dublin, Ireland), Eurosilicone Cristalline implants (GC Aesthetics, Dublin, Ireland), and Mentor Siltex implants (Mentor, Irvine, CA). The histological characteristics of the inner and outer capsules was analyzed using a validated assessment tool. RESULTS: The study included data from 588 patients and 1128 implants. Double capsule formation was found around 25 implants resulting in an overall prevalence of 2.5% for textured implants. Mentor implants with a Siltex surface had a double capsule prevalence of 0.72%, which was significantly lower than the prevalence for Allergan implants with a Biocell surface (7.8%), (P<.001), and Eurosilicone implants with a Cristalline surface (3.4%), (P=.03). Histological analysis showed that inner capsules had lower cellular density (P=.04) and were more calcified (P=.03) compared with outer capsules. CONCLUSIONS: The risk of double capsule formation was highly correlated with the roughness of the breast implant texture, with the risk of double capsule formation around Mentor Siltex implants being significantly lower than that of macrotextured implants. The histological analysis implies that loss of vascularization to the inner capsule results in a lower cellular density and more frequently calcification.

Development and Validation of a Diagnostic Histopathological Scoring System for Capsular Contracture Based on 720 Breast Implant Capsules.

BACKGROUND: Capsular contracture is traditionally evaluated with the Baker classification, but this has notable limitations regarding reproducibility and objectivity. OBJECTIVES: The aim of this study was to develop and validate procedure-specific histopathological scoring systems to assess capsular contracture severity. METHODS: Biopsies of breast implant capsules were used to develop histopathological scoring systems for patients following breast augmentation and breast reconstruction. Ten histological parameters were evaluated by multivariable logistic regression to identify those most associated with capsular contracture. Significant parameters (P < .05) were selected for the scoring systems and assigned weighted scores (1-10). Validation was assessed from the area under the curve (AUC) and the mean absolute error (MAE). RESULTS: A total of 720 biopsies from 542 patients were included. Four parameters were selected for the augmentation scoring system, namely, collagen layer thickness, fiber organization, inflammatory infiltration, and calcification, providing a combined maximum score of 26. The AUC and MAE for the augmentation scoring system were 81% and 0.8%, which is considered strong. Three parameters were selected for the reconstruction scoring system, namely, fiber organization, collagen layer cellularity, and inflammatory infiltration, providing a combined maximum score of 19. The AUC and MAE of the reconstruction scoring system were 72% and 7.1%, which is considered good. CONCLUSIONS: The new histopathological scoring systems provide an objective, reproducible, and accurate assessment of capsular contracture severity. We propose these novel scoring systems as a valuable tool for confirming capsular contracture diagnosis in the clinical setting, for research, and for implant manufacturers and insurance providers in need of a confirmed capsular contracture diagnosis.

Atypical fibroxanthoma and pleomorphic dermal sarcoma: Local recurrence and metastasis in a nationwide population-based cohort of 1118 patients.

BACKGROUND: The prognosis of patients with atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) remains uncertain and no standardized follow-up programs have been established. OBJECTIVE: To recommend a standardized follow-up program of patients with AFX and PDS based on nationwide long-term estimates of local recurrence and metastasis. METHODS: All patients with AFX and PDS in Denmark between 2002 and 2022 were included. Danish National Registries were used to estimate the risks of local recurrence and metastasis for AFX and PDS. RESULTS: The 5-year risk of local recurrence was 10% for AFX and 17% for PDS. The 5-year risk of metastasis was 0.8% for AFX and 16% for PDS. PDS metastasized within 3 years in >90% of the patients with the lungs as the primary metastasis site (50%). Invasion beyond the subcutis, perineural/intravascular infiltration, and increasing age significantly increased the risk of PDS relapse. LIMITATIONS: Risk of misclassification and lack of detailed surgical information. CONCLUSION: The follow-up of patients with AFX can be limited to clinical visits for 4 years. Patients with PDS should be followed with clinical visits and PET/CT twice a year for the first 3 years and once a year for a minimum of 1 year.

Risk factors for local atypical fibroxanthoma recurrence and progression to pleomorphic dermal sarcoma: A meta-analysis of individualized participant data.

BACKGROUND: Risk factors for local atypical fibroxanthoma (AFX) recurrence and progression to pleomorphic dermal sarcoma (PDS) have not previously been identified. OBJECTIVE: To identify risk factors and provide follow-up suggestions for local AFX recurrence and progression to PDS. METHODS AND MATERIALS: A literature search was performed in the PubMed, EMBASE, and Cochrane databases. The PRISMA and MOOSE guidelines were followed. The risks of local AFX recurrence and progression to PDS were presented as Kaplan-Meier plots and risk factors were presented as hazard ratios (HRs) calculated with univariate and multivariate Cox regression. RESULTS: Five hundred and ninety-eight patients with AFX from 14 studies were included. Age >74 years and male sex significantly increased the risk of local recurrence (HR: 7.31 [95% confidence interval [CI]: 1.78-30.0], p < 0.01 and HR: 2.89 [95% CI: 1.04-8.01], p < 0.05, respectively). There was no difference when comparing wide local excision and Mohs' micrographic surgery (p = 0.89). The risks of local AFX recurrence and progression to PDS after 2 years were <1%. CONCLUSION: A more intensive follow-up regimen could be considered in patients >74 years old and males due to the higher risk of local AFX recurrence.

Immunohistochemical Characteristics of Atypical Fibroxanthoma and Pleomorphic Dermal Sarcoma: A Systematic Review and Meta-Analysis.

BACKGROUND: Differentiating atypical fibroxanthoma (AFX) from pleomorphic dermal sarcoma (PDS) remains a challenge. Increasing the use of immunohistochemistry has led to the proposal of many immunomarkers that may aid in the diagnosis of AFX and PDS. In this meta-analysis, we investigate the immunohistochemical characteristics of AFX and PDS based on suggested immunomarkers in the literature. Second, we identify potential distinctive markers found in the tumors' respective immunohistochemical profiles. METHODS: We included studies using immunomarkers on at least 10 consecutive patients with clinically and histopathologically verified AFX or PDS. The positive rates of the immunomarkers were pooled across the included studies with random-effects models. The immunomarkers were further categorized by a priori-chosen cutoffs in positive rates as positive markers (>90%) or negative markers (<10%). Differences between AFX and PDS were compared with Wald tests. RESULTS: We included 45 studies (1516 tumors) reporting on 35 immunomarkers. CD10 was positive in 94% (95% confidence interval, 87-99) of AFX cases and 100% (95% confidence interval, 99-100) of PDS cases. In accordance with the literature, both AFX and PDS were mainly negative for epithelial markers, melanocytic markers, markers of smooth muscle differentiation, and endothelial markers. None of the examined immunomarkers could distinguish AFX from PDS. CONCLUSIONS: Our results suggest that CD10 is a useful positive immunomarker for both AFX and PDS. We found no difference in immunohistochemical profile when comparing AFX with PDS. Our analysis suggests that CD10, AE1/AE3, CK5/CK6, p63, S100, SOX10, desmin, SMA, CD31, and ERG could be used to differentiate AFX and PDS from other spindle cell neoplasms.

Fat Grafting With Expanded Adipose-Derived Stromal Cells for Breast Augmentation: A Randomized Controlled Trial.

BACKGROUND: The main challenge with fat grafting is loss of some of the graft to postsurgery resorption. Previous studies suggest that adipose-derived stromal cells (ASCs) can improve the volume retention of fat grafts but there is a lack of randomized trials to support the use of ASCs in clinical practice. OBJECTIVES: This trial aimed to investigate whether ASCs improve fat graft volume retention in patients undergoing breast augmentation with lipofilling. METHODS: This was a double-blind, randomized controlled trial of breast augmentation with ASC-enriched fat grafting. Healthy women aged 30 to 45 years were enrolled. First, the participants underwent liposuction to obtain fat for culture expansion of ASCs. Then, the participants were randomly assigned to undergo a 300- to 350-mL breast augmentation with ASC-enriched fat grafting (10 × 106 ASCs/mL fat graft) to 1 of their breasts and placebo-enriched fat grafting of identical volume to the contralateral breast. The primary outcome was fat graft volume retention after a 1-year follow-up measured with MRI. The trial is registered at www.clinicaltrialsregister.eu (EudraCT-2014-000510-59). RESULTS: Ten participants were included in the trial; all completed the treatment and follow-up. No serious adverse events occurred. Fat graft volume retention after 1 year was 54.0% (95% CI, 30.4%-77.6%) in the breasts treated with ASC-enriched fat grafting (n = 10) and 55.9% (95% CI, 28.9%-82.9%) in the contralateral breasts treated with placebo-enriched fat grafting (n = 10) (P = 0.566). CONCLUSIONS: The findings of this trial do not support that ASC-enriched fat grafting is superior to standard fat grafting for breast augmentation.

Histological Analyses of Capsular Contracture and Associated Risk Factors: A Systematic Review.

BACKGROUND: Capsular contracture is a severe complication to breast surgery with implants. Previous studies suggest multiple risk factors are associated with capsular contracture, but the etiology is still unknown. We performed a literature review to investigate existing studies on histological analyses of breast implant capsules and how clinical risk factors impact the capsule morphology. METHODS: The literature search was conducted in PubMed. Studies that performed histological analyses of breast implant capsules were included. Animal studies or studies with a study population of less than five patients were excluded. RESULTS: Fifty-two studies were included. The histological analyses showed that the breast implant capsules were organized in multiple layers with an inner layer of synovial-like metaplasia which was reported to diminish in capsules with capsular contracture. The remaining layers of the capsule mostly consisted of collagen. The alignment of the collagen fibers differed between contracted and non-contracted capsules, and capsules with higher Baker grade were generally thickest and contained more tissue inflammation. Studies investigating capsules affected by radiotherapy found a more pronounced inflammatory response and the capsules were generally thicker and fibrotic compared with nonirradiated capsules. CONCLUSIONS: The included studies offer valuable insights into the histological changes caused by capsular contracture and their relation to clinical risk factors. Further studies with larger sample sizes and more strict inclusion criteria are needed to further investigate implant capsules and the role of the synovial-like metaplasia for the development of capsular contracture. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors https://www.springer.com/00266 .

Deskinning in Inverted-T Mastopexy and Augmentation Mastopexy: A Retrospective Cohort Study.

BACKGROUND: Most surgeons choose to de-epithelialize when performing a mastopexy to minimize the risk of nipple-areola-complex (NAC) necrosis. Preservation of the dermis and thus the subdermal plexus is thought to be crucial for the survival of the NAC. However, this has never been scientifically proven. Deskinning involves resection of the epidermis and the dermis and is a timesaving alternative to de-epithelialization. In this study, we present data from mastopexy patients with or without implant surgery with total deskinning of the Wise pattern. METHODS: From September 2012 to March 2020, a single surgeon performed all inverted-T mastopexies using the deskinning technique. The patients were included retrospectively, and data were collected by reviewing the patients' medical records with emphasis on NAC necrosis. RESULTS: The cohort consisted of 274 consecutive patients who underwent bilateral mastopexy. Of these, 134 patients underwent mastopexy as the only procedure and 140 patients underwent mastopexy in combination with implant surgery. The median follow-up was 29 months (IQR 13-40 months). No complete NAC-necrosis occurred. Unilateral, partial NAC necrosis occurred in three patients who underwent mastopexy in combination with implant surgery. CONCLUSION: The NAC necrosis rate following inverted-T mastopexy using the deskinning technique is comparable to the rate of NAC-necrosis reported in the literature following mastopexy using the de-epithelialization technique. Our findings support that the use of deskinning is a safe and time-efficient method for patients undergoing inverted-T mastopexy. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the table of Contents or the online Instructions to Authors www.springer.com/00266.

Cryopreservation of adipose-derived stromal/stem cells using 1-2% Me2SO (DMSO) in combination with pentaisomaltose: An effective and less toxic alternative to comparable freezing media.

Mesenchymal stromal/stem cells (MSCs) derived from bone marrow, umbilical cord and especially adipose tissue are increasingly being explored for their therapeutic potential to treat a wide variety of diseases. A prerequisite for most allogeneic off-the-shelf and some autologous MSC therapies is the ability to safely and efficiently cryopreserve cells during production or for storage prior to treatment. Dimethyl sulfoxide (Me2SO) is still the commonly used gold standard cryoprotectant (CPA). However, undesirable cellular impacts and side effects of Me2SO have led to an increasing demand for the development of safe and effective alternatives. This study investigated the effect of pentaisomaltose as a CPA for cryopreservation of adipose-derived stromal/stem cells (ASCs). We compared pentaisomaltose-based freezing media containing 1% Me2SO (PIM1) or 2% Me2SO (PIM2) to our in-house freezing media formulation containing 10% Me2SO (STD10) and to CryoStor freezing media containing 2% or 10% Me2SO (CS2 and CS10). We assessed the recovery of viable ASCs, their phenotype, differentiation potential, proliferation potential, and migratory potential. Further, their immunomodulatory potential was assessed by measuring their ability to suppress T cell proliferation and express immunomodulatory markers. The results showed that the post-thaw viability of ASCs cryopreserved with STD10, CS10 and PIM2 was improved compared to that of CS2. The recovery of ASCs with PIM1 and PIM2 was also improved compared to that of CS2. Proliferation and migration were comparable among the tested freezing media. The results showed no difference in the induction of PDL1, PDL2 or IDO1 expression. Nevertheless, the potential of cryopreserved ASCs to suppress T cell proliferation was reduced when the Me2SO concentration was reduced (CS10>STD10>CS2 and PIM2>PIM1). Altogether, the migratory and immunomodulatory potential combined with improved recovery indicate that the addition of pentaisomaltose in the freezing media may allow for the reduction of the Me2SO concentration to 2% while retaining a more potent cell product that what is recovered using comparable freezing media. With the desire to reduce the amount of Me2SO, these results suggest that 2% and potentially even 1% Me2SO in combination with 10% pentaisomaltose could be an effective and less toxic alternative to comparable freezing media.

Effect, Feasibility, and Clinical Relevance of Cell Enrichment in Large Volume Fat Grafting: A Systematic Review.

Large volume fat grafting is limited by unpredictable volume loss; therefore, methods of improving graft retention have been developed. Fat graft enrichment with either stromal vascular fraction (SVF) cells or adipose tissue-derived stem/stromal cells (ASCs) has been investigated in several animal and human studies, and significantly improved graft retention has been reported. Improvement of graft retention and the feasibility of these techniques are equally important in evaluating the clinical relevance of cell enrichment. We conducted a systematic search of PubMed to identify studies on fat graft enrichment that used either SVF cells or ASCs, and only studies reporting volume assessment were included. A total of 38 articles (15 human and 23 animal) were included to investigate the effects of cell enrichment on graft retention as well as the feasibility and clinical relevance of cell-enriched fat grafting. Improvements in graft retention, the SVF to fat (SVF:fat) ratio, and the ASC concentration used for enrichment were emphasized. We proposed an increased retention rate greater than 1.5-fold relative to nonenriched grafts and a maximum SVF:fat ratio of 1:1 as the thresholds for clinical relevance and feasibility, respectively. Nine studies fulfilled these criteria, whereof 6 used ASCs for enrichment. We found no convincing evidence of a clinically relevant effect of SVF enrichment in humans. ASC enrichment has shown promising results in enhancing graft retention, but additional clinical trials are needed to substantiate this claim and also determine the optimal concentration of SVF cells/ASCs for enrichment. LEVEL OF EVIDENCE: 4.

PROphylactic closed incision Negative-PRESSure treatment in open incisional hernia repair: Protocol for a multicenter randomized trial (PROPRESS study).

Background: Negative Pressure Therapy in closed incisions (ciNPT) after surgery has shown positive effects including reduction of Surgical Site Infection (SSI) incidence. In patients undergoing elective open incisional hernia repair, however, ciNPT is not standard care, perhaps due to high-quality evidence still not provided. This study hypothesizes that this patient group would benefit from ciNPT by reducing wound complications and improving postoperative quality of life. Method: This is a multicenter Randomized Controlled Trial (RCT) including a total of 110 patients allocated in a 1:1 ratio with one intervention arm and one active control arm receiving ciNPT (i.e., Prevena™) and standard wound dressing, respectively. The primary outcome is the incidence of SSI at 30 days postoperatively and secondary outcomes are 1) pooled incidence of Surgical Site Occurrence (SSO), 2) patient-reported pain and satisfaction with the scar, and 3) hernia-related quality of life. Conclusion: Patients undergoing elective open incisional hernia repair are fragile with a high risk of wound complication development. This multicenter RCT seeks to deliver the high-quality evidence needed to establish the role ciNPT must play for exactly this group with the aim of reducing SSI incidence and health economic costs, and finally improving quality of life. There are no theoretical or clinical experience of unwanted consequences of this treatment.

Breast reconstruction with mentor anatomical implants and the risk of implant rotation: A retrospective study of 1134 women.

BACKGROUND: Implant rotation is a known complication to breast reconstruction using anatomical implants. However, there is a lack of large studies investigating the risk of implant rotation and potential predisposing risk factors. METHOD: We reviewed the medical records of all patients who underwent breast reconstruction with Mentor anatomical implants from 2010 to 2021 at two Danish hospitals. We compared the risk of implant rotation between one- and two-stage breast reconstruction using univariate logistic regression. We analyzed the effect of biological mesh, immediate versus delayed reconstruction, and use of a higher final expander volume than the permanent implant volume on the risk of implant rotation. Finally, we analyzed the success rate of revision surgery for implant rotation. RESULTS: In total, 1134 patients were enrolled. Patients who underwent two-stage breast reconstruction (n = 720) had a significantly higher risk of implant rotation than those who underwent one-stage breast reconstruction (n = 426; 11% vs. 5%, p < 0.01). There was no significant association between implant rotation and the use of biological mesh, immediate breast reconstruction, or use of a higher final expander volume than the permanent implant volume. The success rate of revision surgery after implant rotation was 73% (62/85 rotations). CONCLUSIONS: Two-stage breast reconstruction significantly increased the risk of implant rotation compared to one-stage breast reconstruction. The overall risk of implant rotation was low and success rate of revision surgery was high. These findings suggest that anatomical implants are safe to use for breast reconstruction. However, surgeons and patients should be aware of the increased risk of implant rotation after two-stage reconstruction.

Silicone Leakage from Breast Implants Is Determined by Silicone Cohesiveness: A Histological Study of 493 Patients.

BACKGROUND: Silicone leakage from breast implants is a concern with potential implications for patient health. This study aimed to quantify and model silicone leakage from implants to the breast implant capsule and to investigate whether silicone cohesiveness affected the silicone leakage rate. METHODS: Silicone content in the breast implant capsule was quantified histologically by measuring the area of silicone deposits. This was used to model silicone leakage over time based on the time of implantation. The effect of cohesiveness on silicone leakage was investigated across all implant brands with declared cohesiveness and in a subanalysis comparing only Mentor cohesive I implants with cohesive II and III implants. RESULTS: The study included 493 patients with 872 breasts and a median time of implantation of 13.0 years (range 0.4 to 51 years). The modeling of silicone leakage from intact implants showed that leakage and the acceleration of the leakage rate were significantly higher in low-cohesive implants than in highly cohesive implants (p<0.05). This was confirmed when analyzing only Mentor implants (p<0.05) and in the case of implant rupture (p<0.01) where low-cohesive implants also leaked significantly more than highly cohesive implants. CONCLUSIONS: Our results suggest that highly cohesive implants are superior to low-cohesive implants in preventing silicone leakage. Due to the accelerating rate of silicone leakage especially found in low-cohesive implants, we propose that exchange of low-cohesive implants could be discussed with patients 10 to 15 years after implantation to minimize silicone leakage even in the absence of implant rupture.

Pharmacokinetics of Locally Applied Antibiotic Prophylaxis for Implant-Based Breast Reconstruction.

Importance: Antibiotic irrigation of breast implants is widely used internationally, but no clinical study has investigated the pharmacokinetics of antibiotic prophylaxis in the breast implant pocket. Objectives: To evaluate how long locally applied gentamicin, cefazolin, and vancomycin concentrations in the implant pocket remain above the minimum inhibitory concentration (MIC) for the most common bacterial infections and to measure systemic uptake. Design, Setting, and Participants: This prospective cohort study was performed at the Department of Plastic Surgery and Burns Treatment, Rigshospitalet, Copenhagen, Denmark, between October 25, 2021, and September 22, 2022, among 40 patients undergoing implant-based breast reconstruction who were part of the ongoing BREAST-AB trial (Prophylactic Treatment of Breast Implants With a Solution of Gentamicin, Vancomycin and Cefazolin Antibiotics for Women Undergoing Breast Reconstructive Surgery: a Randomized Controlled Trial). Patients were randomized to receive locally applied gentamicin, cefazolin, and vancomycin or placebo. Samples were obtained from the surgical breast drain and blood up to 10 days postoperatively. Exposures: The breast implant and the implant pocket were irrigated with 160 µg/mL of gentamicin, 2000 µg/mL of cefazolin, and 2000 µg/mL of vancomycin in a 200-mL saline solution. Main Outcomes and Measures: The primary outcome was the duration of antibiotic concentrations above the MIC breakpoint for Staphylococcus aureus according to the Clinical and Laboratory Standards Institute: gentamicin, 4 µg/mL; cefazolin, 2 µg/mL; and vancomycin, 2 µg/mL. Secondary outcomes included the time above the MIC for Pseudomonas aeruginosa and other relevant bacteria, as well as systemic uptake. Results: The study included 40 patients (median age, 44.6 years [IQR, 38.3-51.4 years]; median body mass index, 23.9 [IQR, 21.7-25.9]) with a median number of 3 drain samples (range, 1-10 drain samples) and 2 blood samples (range, 0-6 blood samples). Vancomycin and cefazolin remained above the MIC for S aureus significantly longer than gentamicin (gentamicin, 0.9 days [95% CI, 0.5-1.2 days] for blood samples vs 6.9 days [95% CI, 2.9 to 10.9 days] for vancomycin [P = .02] vs 3.7 days [95% CI, 2.2-5.2 days] for cefazolin [P = .002]). The gentamicin level remained above the MIC for P aeruginosa for 1.3 days (95% CI, 1.0-1.5 days). Only cefazolin was detectable in blood samples, albeit in very low concentrations (median concentration, 0.04 µg/mL [range, 0.007-0.1 µg/mL]). Conclusions and Relevance: This study suggests that patients treated with triple-antibiotic implant irrigation during breast reconstruction receive adequate prophylaxis for S aureus and other common implant-associated, gram-positive bacteria. However, the protection against P aeruginosa may be inadequate.

Antibiotic implant irrigation and deep infection: A retrospective study of 1508 patients undergoing breast reconstruction with implants.

BACKGROUND: Antibiotic implant irrigation is increasingly used to prevent deep infection after implant-based breast reconstruction. However, there is limited evidence of the clinical effect. In this study, we compare the risk of a deep infection in a Danish population of women who either received antibiotic implant irrigation with gentamycin or vancomycin, or no irrigation. METHODS: We retrospectively reviewed consecutive patients undergoing all types of breast reconstruction with implants at Rigshospitalet and Herlev Hospital, Denmark, in 2010-2019. Logistic regression was used to compare the risk of deep infection between no irrigation and irrigation with gentamicin or vancomycin, and to account for the difference in risk between patient subgroups and risk factors. RESULTS: We included 1508 patients who received antibiotic irrigation with gentamicin (500 patients), vancomycin (304 patients) or no irrigation (704 patients). The univariable risk analysis showed a significant decreased risk of deep infection using gentamicin irrigation compared with no irrigation (OR 0.58, p<0.05). However, when adjusting for risk factors for infection, there was no significant decrease in the risk of infection when using gentamicin (OR 0.90, p=0.71) or vancomycin (OR 1.0, p=0.99) compared with the control group. CONCLUSIONS: We found no significant effect of using antibiotic implant irrigation after isolating it from risk factors for deep infection. However, due to the limitations of the study, we cannot conclude that there is no effect of antibiotic implant irrigation. There is a need for a randomized, placebo-controlled trial to investigate the effect, and potential side-effects, of antibiotic implant irrigation.

How to Report Data on Bilateral Procedures and Other Issues with Clustered Data: The CLUDA Reporting Guidelines.

BACKGROUND: Research in plastic surgery often includes bilateral procedures. This gives rise to issues with clustered data. Clustering is when individual data points within a data set are internally related. However, many authors do not account for clustering within their data, which can lead to incorrect statistical conclusions. METHODS: In February of 2020, the authors searched PubMed to investigate the prevalence of reporting issues with bilateral breast procedures in plastic surgery literature. The review focused on breast surgery, as it often involves bilateral procedures and, therefore, clustering. Based on the review, the authors developed guidelines for how to identify and address clustered data. The guidelines were modified by a multidisciplinary group consisting of a biostatistician with expertise in clustered data at the Section of Biostatistics, University of Copenhagen, and three doctors (M.D.s and Ph.D.s) with expertise in statistical analysis and scientific methodology from the Copenhagen University Hospital, Rigshospitalet. RESULTS: A total of 113 studies were included in the review. Seventy-five studies (66 percent) contained clustered data, but only eight studies (11 percent) took clustering into account in the statistical analysis. These results were used to develop the Clustered Data, or CLUDA, reporting guidelines which consist of two sections: one to identify clustering and one for reporting and analyzing clustered data. CONCLUSIONS: Clustered data are abundant in plastic surgery literature. The authors propose using the Clustered Data reporting guidelines to identify and report clustered data and consulting with a biostatistician when designing a study.