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Background: We aimed to determine if Area Deprivation Index (ADI) is associated with self-reported metrics socioeconomic status (SES), and to assess the relationship between ADI and preoperative score on common patient reported outcome scores (PROS)., Methods: Patients presenting for outpatient orthopaedic surgery completed Patient-Reported Outcome Metric Information System (PROMIS) and joint-specific PROS. ADI was determined from geocoded home address. Sociodemographic data was collected from self-reported survey. Tests of association were used to describe the relationship between ADI and sociodemographic factors as well as the correlation between ADI and PROS. Extreme group analysis was used to examine which PROS may be subject to clinically meaningful variation., Results: ADI was associated with self-reported SES. ADI was correlated with score on all baseline PROS. Extreme group analysis showed that low SES was associated with clinically meaningful differences in some, but not all, PROS., Conclusion: ADI is associated with self-reported measures of SES in an orthopaedic outpatient surgical population. Lower SES correlates with worse function to a clinically significant degree for some PROS. SES should be considered in the context of preoperative symptom severity in outpatient orthopaedic surgery patients. ADI may be a useful adjunct to self-reported measures of SES for this purpose., Competing Interests: N. N. O'Hara receives stock or stock options from Arbutus Medical, Inc. unrelated to this research. C. G. Langhammer is a paid consultant for DePuy Synthes unrelated to this research. The remaining authors report no conflicts., (© 2024 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Objectives: The purpose of this study was to define the rate of preoperative opioid use among patients undergoing hip arthroscopy, ascertain which clinical factors are associated with opioid use, and assess the effect of preoperative opioid usage on preoperative patient-reported outcome (PRO) measures., Methods: A single institution orthopedic registry was retrospectively analyzed for patients undergoing hip arthroscopy for femoroacetabular impingement (FAI) syndrome with or without labral tear between 2015 and 2022. Patients completed Patient-Reported Outcomes Measurement Information System (PROMIS) in six domains, Numeric Pain Scores (NPS), and Musculoskeletal Outcomes Data Evaluation and Management System expectations domain preoperatively. Patients' charts were reviewed to determine demographic factors and identify any active opioid prescription within 6 weeks before surgery. Bivariate analysis was used to determine associations between preoperative opioid use and baseline PROs. Statistically significant bivariate associations were further tested by multivariate analysis to determine independent predictors., Results: A total of 123 patients were included (age 39.7 ​± ​12.0 years; 87 females; body mass index 27.4 ​± ​5.7 kg/m 2 ). There were 21 patients (17%) using opioids preoperatively. Prior orthopedic or other surgery and lower education level were associated with preoperative opioid use. Patients with preoperative opioid use scored statistically significantly worse compared with those without preoperative opioid use on baseline PROMIS Physical Function (38.6 vs 40.5, p ​= ​0.01), Pain Interference (65.9 vs 60.2, p ​= ​0.001), Fatigue (60.7 vs 51.6, p ​= ​0.005), Social Satisfaction (38.2 vs 43.2, p ​= ​0.007), and Depression (54.2 vs 48.8, p ​= ​0.01). Preoperative opioid use was also associated with statistically significantly worse preoperative NPS for both the operative hip (6.3 vs 4.6, p ​= ​0.003) and whole body (3.0 vs 1.4, p ​= ​0.008). Preoperative opioid use was an independent predictor of worse baseline PROMIS Pain Interference, Fatigue, Social Satisfaction, and NPS for the operative hip., Conclusion: Patients using opioids preoperatively had worse baseline PROs for physical function, pain, social satisfaction, and depression than those not using opioids preoperatively. When controlling for confounding variables, preoperative opioid use was independently predictive of worse baseline pain, fatigue, and social satisfaction., Level of Evidence: Level III, prognostic study., Competing Interests: Declaration of competing interest R. Frank Henn III reports financial support was provided by The James Lawrence Kernan Hospital Endowment Fund, Incorporated. Natalie L. Leong reports was provided by United States Department of Veterans Affairs. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Mental health has been shown to play an important role in patient-reported outcomes (PRO); however, there is a general lack of literature describing patient-reported outcome measurement information system (PROMIS) depression and anxiety computer adaptive tests in elective knee surgery patients. The purpose of our study was to assess the prevalence of depression and anxiety symptoms before and after elective knee surgery and to determine whether these symptoms influence postoperative functional outcomes. An institutional review board-approved prospective orthopaedic registry was retrospectively queried for patients undergoing elective knee surgery from June 2015 to November 2018. Electronic surveys collecting patient demographic information and PROs were administered pre- and postoperatively. Of the 663 patients that completed baseline questionnaires, 466 completed 2-year follow-up (70.3%). PROs included PROMIS depression, PROMIS anxiety, International Knee Documentation Committee Subjective Knee Form (IKDC), and PROMIS physical function (PF). Wilcoxon rank sum and Spearman's rank order correlation were utilized to determine associations between variables. Multivariable analysis was used to control for confounding variables. Average PROMIS depression and anxiety scores significantly improved 2 years after surgery. PROMIS depression and anxiety scores significantly correlated with each other. PROMIS depression and anxiety scores significantly correlated with PROMIS PF and IKDC scores. After controlling for confounders on multivariable analysis, worse 2-year PROMIS anxiety was predictive of less functional improvement and worse 2-year PF and IKDC, while worse 2-year PROMIS depression was predictive of less improvement in IKDC. This study confirms the important relationship between mental health and functional outcomes. Given that psychiatric comorbidities are potentially modifiable with treatment, proper recognition could potentially lead to better orthopaedic outcomes. In addition, the prevalence of depression and anxiety symptoms postoperatively, as documented by PROMIS computer adaptive tests, may act as a barrier to achieving optimal functional outcomes after elective knee surgery. LEVEL OF EVIDENCE:  Level III., Competing Interests: None declared., (Thieme. All rights reserved.)

Purpose: As stakeholders seek to improve patient outcomes while maintaining cost-effectiveness in an increasingly expensive healthcare system, metrics such as patient satisfaction are becoming more important. This present study sought to identify factors associated with and independently predictive of better surgical satisfaction two years following hand and wrist surgery., Methods: Patients undergoing hand and wrist surgery at an urban outpatient institution were enrolled preoperatively into a surgical registry and assessed two years postoperatively. Patient satisfaction with surgery was measured at two years postoperatively with the Surgical Satisfaction Questionnaire (SSQ-8). Bivariate analysis determined associations between postoperative satisfaction and patient demographics, injury specifiers, medical history, and multiple patient-reported outcomes (PROs). Multivariable analysis determined independent predictors of two-year postoperative satisfaction following hand and wrist surgery., Results: Better surgical satisfaction was associated with having never smoked, no preoperative opioid use, lack of an accompanying legal claim, lack of a workers compensation claim, no clinical history of depression/anxiety, less comorbidities, and higher preoperative expectations.Various PROs relating to function, pain, activity, and general health at both baseline and two years demonstrated associations with postoperative satisfaction. Multivariable analysis confirmed that never smoking, lack of a legal claim, and better preoperative Brief Michigan Hand Questionnaire scores were independently predictive of better surgical satisfaction two years following hand and wrist surgery., Conclusion: At two years following hand and wrist surgery, better patient satisfaction was best predicted by never smoking, no related legal claim, and better baseline Brief Michigan Hand Questionnaire scores., Level of Evidence: III., Competing Interests: None declared, (© 2024 Society for Indian Hand Surgery and Micro Surgeons. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Background: The purpose of this study was to identify preoperative factors associated with worse postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) pain interference (PI) scores 2 years after hand and wrist surgery. We hypothesized that older age, more comorbidities, increased substance use, and lower socioeconomic status would correlate with worse 2-year PROMIS PI scores., Methods: This study was a retrospective review of prospectively acquired data on 253 patients. Surveys were administered within 1 week of surgery and 2 years postoperatively. Bivariate and multivariable analyses were conducted to identify significant predictors of worse 2-year PROMIS PI scores and change in PROMIS PI scores., Results: Older age, higher body mass index, more comorbidities, lower preoperative expectations, more prior surgeries, unemployment, smoking, higher American Society of Anesthesiologists (ASA) score, and multiple other socio-demographic factors were correlated with worse 2-year PROMIS PI scores ( P ≤ .018). Similar factors were also correlated with less improvement in 2-year PROMIS PI scores ( P ≤ .048). Worse scores on all preoperative patient-reported outcome measures correlated with worse 2-year PROMIS PI scores ( P ≤ .007). Multivariable analysis identified smoking history, less frequent alcohol consumption, worse preoperative PROMIS social satisfaction and Numeric Pain Scale whole body scores, and higher ASA scores as independent predictors of worse 2-year PROMIS PI. The same factors in addition to better baseline PROMIS PI were predictive of less improvement in 2-year PROMIS PI., Conclusion: Numerous preoperative factors were predictive of worse postoperative 2-year PROMIS PI and less improvement in 2-year PROMIS PI for patients undergoing hand and wrist surgery., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: RAP—Globus Medical; royalty or licenses, consulting fee, paid presenter or speaker, stock or stock options. CGL—Synthes; consulting fee.

Aims & Objectives: Meaningful clinical interpretation of orthopaedic patient-reported outcome scores remains challenging. Grouping scores may be more meaningful than individual score analysis. The purpose of this study was to determine if grouping knee surgery patients into four preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) clusters would have prognostic value for two-year postoperative outcomes., Materials & Methods: 488 of 697 (70%) patients undergoing elective knee surgery at a single urban institution were enrolled in an orthopaedic registry and completed two-year follow up. Patients were administered questionnaires for PROMIS, International Knee Documentation Committee Score (IKDC), Marx Activity Rating Scale (MARS), and Surgical Satisfaction (SSQ-8). A k-means cluster analysis was performed to identify preoperative PROMIS clusters. Chi-square or Kruskal-Wallis tests were conducted for bivariate analyses. Least-squares multiple linear regression models were performed to identify if cluster group was an independent predictor., Results: Cluster analysis revealed four clusters of patients. Psychological distress was most significant in determining classification. More impaired clusters were associated with higher rates of arthroplasty, African American race, preoperative opioid use, lower income, higher comorbidity index, and other sociodemographic and operative factors. Worse preoperative cluster status was associated with higher chance of achieving minimally clinically important change (MCID) on all metrics except PROMIS Pain Interference (PI), IKDC, and MARS. Multivariable analysis confirmed better preoperative cluster as predictive of better PROMIS Physical Function (PF), PI, IKDC scores, and satisfaction. Worse preoperative cluster was predictive of greater improvement on PF and PI but not IKDC., Conclusion: Preoperative PROMIS clusters have prognostic value in predicting outcomes for knee surgery patients. Better preoperative cluster function predicts superior outcomes. While worse preoperative cluster predicts worse outcome, all clusters still significantly improve, so worse preoperative cluster is not a contraindication to surgery., Competing Interests: All authors certify that they have no commercial associations (e.g., consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. On the Disclosure of Potential Conflicts of Interest forms, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work., (© 2023 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights reserved.)

Background: The pattern of glenoid bone loss (GBL) in anterior glenohumeral instability is well described. It was recognized recently that posterior GBL after instability has a posteroinferior pattern., Purpose/hypothesis: The purpose of this study was to compare GBL patterns in a matched cohort of patients with anterior versus posterior glenohumeral instability. The hypothesis was that the GBL pattern in posterior instability would be more inferior than the GBL pattern in anterior instability., Study Design: Cohort study; Level of evidence, 3., Methods: In this multicenter retrospective study, 28 patients with posterior instability were matched with 28 patients with anterior instability by age, sex and number of instability events. GBL location was defined using a clockface model. Obliquity was defined as the angle between the long axis of the glenoid and a line tangent to the GBL. Superior and inferior GBL were measured as areas and defined relative to the equator. The primary outcome was the 2-dimensional characterization of posterior versus anterior GBL. The secondary outcome was a comparison of the posterior GBL patterns in traumatic and atraumatic instability mechanisms in an expanded cohort of 42 patients., Results: The mean age of the matched cohorts (n = 56) was 25.2 ± 9.87 years. The median obliquity of GBL was 27.53° (interquartile range [IQR], 18.83°-47.38°) in the posterior cohort and 9.28° (IQR, 6.68°-15.75°) in the anterior cohort ( P < .001). The mean superior-to-inferior bone loss ratio was 0.48 ± 0.51 in the posterior cohort and 0.80 ± 0.55 ( P = .032) in the anterior cohort. In the expanded posterior instability cohort (n = 42), patients with traumatic injury mechanism (n = 22), had a similar GBL obliquity compared to patients with an atraumatic injury mechanism (n = 20) (mean, 27.73° [95% CI, 20.26°-35.20°] vs 32.20° [95% CI, 21.27°-43.14°], respectively) ( P = .49)., Conclusion: Posterior GBL occurred more inferiorly and at an increased obliquity compared with anterior GBL. This pattern is consistent for traumatic and atraumatic posterior GBL. Bone loss along the equator may not be the most reliable predictor of posterior instability, and critical bone loss may be reached more rapidly than a model of loss along the equator may predict., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: M.D.B. has received education payments from Supreme Orthopedic Systems. S.A.H. has received education payments from Arthrex. M.N.G. has received education payments from Supreme Orthopedic Systems and speaking fees from Arthrex. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2023.)

Purpose: The purpose of this study is to determine if preoperative expectations (PE) are an independent predictor of greater 2-year outcomes and greater improvement from baseline in shoulder surgery patients., Methods: Two-hundred and sixteen patients who underwent shoulder surgery at one institution were studied. Patients completed both preoperative and 2-year follow-up questionnaires including PROMIS (Patient-Reported Outcome Measurement Information System) computer-adaptive testing in six domains, American Shoulder and Elbow Surgeons (ASES) score, shoulder numeric pain scale (NPS), and the Marx Shoulder Activity Rating Scale (MARS). PE were measured using the Musculoskeletal Outcomes and Data Evaluation Management System (MODEMS) expectations domain, and satisfaction was measured via the Surgical Satisfaction Questionnaire (SSQ-8)., Results: The mean PE score was 86.2 ± 17.8. Greater PE were associated with significantly better 2-year scores for ASES, NPS, MARS, SSQ8, and PROMIS domains of Physical Function, Fatigue, Pain Interference Fatigue and Social Satisfaction. Multivariable analyses demonstrated that greater PE were an independent predictor of both better 2-year scores and greater improvement for PROMIS SS (p < 0.001), ASES (p = 0.007), and shoulder NPS (p = 0.011)., Conclusion: Greater PE are positively associated with numerous patient-based outcomes 2 years after surgery. With regards to pain relief, shoulder function, and social satisfaction, higher PE are also predictive of better outcome scores and more improvement. This study suggests that preoperative assessment of shoulder surgery PE is important, and that counseling patients to optimize realistic expectations may lead to superior outcomes., Level of Evidence: III., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: The purpose of this study was to analyze the correlation between baseline depression and anxiety and preoperative functional status in hip arthroscopy patients., Methods: A prospective, institutional review board-approved orthopaedic registry was used to retrospectively study 104 patients undergoing hip arthroscopy. Enrolled patients were administered baseline questionnaires for Patient-Reported Outcomes Measurement Information System (PROMIS) domains, Musculoskeletal Outcomes Data Evaluation and Management System (MODEMS) preoperative expectations, and Numeric Pain Scale (NPS)., Results: The average baseline PROMIS Depression and Anxiety scores were 49.9 ± 9.8 and 55.5 ± 9.3, respectively. Bivariate analysis demonstrated that greater baseline PROMIS Anxiety correlated with worse preoperative PROMIS PI (p < 0.001), Fatigue (p < 0.001), Social Satisfaction (p < 0.001), and NPS score (p = 0.013). Bivariate analysis showed that greater PROMIS Depression correlated with worse preoperative PROMIS PF (p = 0.001), PI (p < 0.001), Fatigue (p < 0.001), SS (p < 0.001), and NPS score (p = 0.004). After controlling for confounders, multivariable analysis confirmed increased PROMIS Depression as an independent predictor of worse preoperative PROMIS PF (p = 0.009), MODEMS Expectations (p = 0.025), and NPS score (p = 0.002). Increased PROMIS Anxiety was predictive of worse baseline PROMIS PI (p < 0.001), Fatigue (p < 0.001), and Social Satisfaction (p < 0.001). A previous clinical diagnosis of depression or anxiety was only an independent predictor of worse baseline PROMIS Fatigue (p = 0.002) and was insignificant in all other models., Conclusion: Increasing severity of depression and anxiety correlated with and predicted worse functional status at baseline in hip arthroscopy patients. As compared to clinical diagnosis of anxiety and depression, PROMIS metrics have superior utility in recognizing potentially modifiable mental health concerns that predict worse preoperative status. Ultimately, the study identifies an at-risk population undergoing hip arthroscopy that requires particular attention and potential mental health intervention in the preoperative setting., Level of Evidence: III., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Background: Available surveys that evaluate shoulder strength and pain often combine rotator cuff muscles making the test unable to differentiate subscapularis tears from other pathology including concomitant supraspinatus, infraspinatus tears. The purpose of this study was to validate a subscapularis-specific shoulder survey (Baltimore Orthopedic Subscapularis Score) as a viable clinical outcome assessment through analysis of psychometric properties., Methods: A 5-question survey was given to a study population of 390 patients, 136 of whom had full thickness rotator cuff tears with a minimum score of 5 (better) and a maximum score of 25 (worse). Surveys were given during the initial consultation, preoperative visit, and postoperative visit. Content validity, construct validity, test-retest reliability, responsiveness to change, internal consistency, and minimal clinically important difference using distribution and anchor-based methods were determined for our subscapularis function survey., Results: A high correlation was reported on test-retest reliability (intraclass correlation coefficient = 0.89). An acceptable internal consistency was reported for all patients surveyed (Cronbach alpha = 0.91). Floor and ceiling effects for patients with rotator cuff pathology were minimized (1% for both). Patients with an isolated subscapularis tear scored worse than supraspinatus/infraspinatus tears and exhibited similar dysfunction as patients with a supraspinatus/infraspinatus/subscapularis tear. An acceptable construct validity was reported with subscapularis-involved tears demonstrating higher scores with significance ( P  < .05). There was excellent responsiveness to change with a standardized response mean of 1.51 and effect size of 1.27 (large > 0.8). The minimal clinically important difference using a distribution and anchor-based method was 4.1 and 4.6, respectively. Among patients with rotator cuff tears in this population, a score of 22 or higher predicts a subscapularis tear 75% of the time, in spite of its low overall prevalence., Conclusion: The subscapularis shoulder score demonstrated acceptable psychometric performance for outcomes assessment in patients with rotator cuff disease. This survey can be used as an effective clinical tool to assess subscapularis function., (© 2022 The Authors.)

Introduction  Studies have shown a link between patients' preoperative expectations and their postoperative satisfaction. However, limited studies exist concerning patient factors associated with higher preoperative expectations in the hand surgery population. This study analyzed preoperative expectation scores of patients undergoing hand surgery and aimed to determine associated patient characteristics. Materials and Methods  A total of 418 elective hand surgery patients aged 15 years and older enrolled in a prospectively collected orthopaedic registry from June 2015 to December 2018 were analyzed. Patients were administered preoperative questionnaires including six Patient-Reported Outcome Measurement Information System domains and other activity and pain scales. Expectation scores were measured using the six domains of the Musculoskeletal Outcomes Data Evaluation and Management System expectations questionnaire. Bivariate and multivariable analyses were conducted to identify independent predictors of higher expectations. Results  Overall, patients had high expectations (≥ 80.0) of their hand surgery. Higher mean expectation scores were seen with females, college graduates, better baseline health status, and fewer prior hand surgeries ( p  < 0.05 for all). No significant associations were found among the Common Procedural Terminology codes and expectations. Multivariable analysis confirmed that college degree ( p  = 0.023) and less pain ( p  = 0.008) were predictive of higher baseline expectations. Conclusion  In sum, more educated patients with less pain at baseline and better baseline health status have higher expectations of their hand surgery. Hand surgeons can use these results to help focus their preoperative counseling and expectation management., Competing Interests: Conflict of Interest None declared., (Society of Indian Hand Surgery & Microsurgeons. All rights reserved.)

Introduction: The aim of this study was to systematically review the literature regarding accurate shoulder prosthetic joint infection (PJI) diagnosis., Methods: Using PRISMA guidelines, we analyzed 25 studies reporting on 5535 patients and 646 infections., Results: Cutibacterium acnes (C. acnes) cultures were positive in 60% of patients. Serum markers WBC, CRP, ESR, and IL-6 appear to lack diagnostic reliability. Synovial IL-6 and alpha-defensin may be more accurate in detecting infections., Conclusion: Synovial IL-6 and alpha-defensin appear to have greater utility than serum markers. These may be incorporated into new criteria to accurately diagnose shoulder PJI., Level of Evidence: IV., (© 2021 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights reserved.)

Background: The effect of postoperative shoulder sling compliance on surgical outcomes is unknown. The goal was to determine an accurate method to measure sling compliance. We compared volunteer recorded sling wear time with temperature-based sensors to monitor sling compliance., Methods: Data loggers sutured at three locations measured heat generated in 15-minute intervals. Slings wearers logged sling wear to accurately cross-reference with temperature sensors. Secondary experiments analyzed whether surrounding ambient temperature can be discerned from actual sling wear. We created an algorithm to describe actual sling wear time as a function of heat recorded and calculated percent wear accuracy., Results: The modified sling was worn for 172 h. The algorithm modeled sling on/off times by analyzing cutoff temperatures. Diagnostic accuracy was >99 % for the three locations, with no statistically significant differences among them. Compared with sling wear, ambient temperature took longer to reach critical temperature values determined by the algorithm, helping distinguish compliance from false positives., Conclusions: The described algorithm can effectively quantify shoulder sling wear time based on heat-generated sensor readings. False positives from ambient temperature are minimal. This measurement method could be used to study the relationship between postoperative sling use and functional outcomes after shoulder surgery.

Background: Cutibacterium acnes is the primary cause of shoulder surgery infections, but the predisposition to larger skin counts and potentially higher risk for postoperative infection remains unclear. This study aimed to quantify risk factors influencing endogenous C. acnes burden and to compare counts among 4 shoulder sites., Methods: C. acnes counts were quantified via a detergent scrub technique for 173 participants. Bivariate and multivariable stepwise linear regression statistical analyses were used to investigate the association of sex, age, ethnicity, degree of hirsutism, diabetes, smoking status, body mass index, and location with counts. A separate Wilcoxon rank-sum test was performed analyzing counts of East/Southeast Asians vs. all other ethnicities., Results: Sex, age, degree of hirsutism, diabetes, smoking status, and body mass index were included in the multivariable stepwise linear regression analysis. The multiple regression analysis isolated individuals <40 years with the highest burden ( P  = .001). Males had a 191% increase in C. acnes counts compared with females ( P  = .001). Increased hirsutism was further indicated to be a risk factor for the male sex although not in a dose-dependent manner ( P  = .027). Wilcoxon rank-sum test results found that East/Southeast Asians had the lowest load ( P  = .019), although not significant in the multivariate model., Conclusion: Surgical site C. acnes infections occur more frequently in younger males, and males <40 years with shoulder-specific hirsutism have the highest preoperative burden. East/Southeast Asians have lower raw counts of C. acnes compared with other ethnicities that may be related to less hirsutism.

Background: Cutibacterium acnes is the most common pathogen in shoulder prosthetic joint infections. Short-contact benzoyl peroxide (BPO) solutions effectively reduce C acnes loads on the shoulder preoperatively. It is unknown how long the effect of BPO lasts. We evaluated C acnes counts 1 week after BPO application. We hypothesized that BPO would decrease C acnes burden with a rebound after 1 week., Methods: Screening of 102 healthy volunteers with no history of shoulder surgery or C acnes infection was performed to establish bacterial counts. Thirty-four participants were selected based on an established threshold. Each was given BPO 5% for 3 consecutive days of application on either the left or right shoulder as indicated by a random number generator. Deep sebaceous gland cultures were obtained with a detergent scrub technique before BPO application, after 3 days of use, and 1 week after BPO treatment commenced., Results: The differences between the logarithmic reduction and the logarithmic rebound at the anterior, lateral, and posterior sites were statistically significant. Anteriorly, the average log reduction was -0.44 and the average log rebound was 0.69 (P = .003). Laterally, reduction was -0.64 and rebound was 0.74 (P = .003). Posteriorly, reduction was -0.63 and rebound was 0.78 (P = .008). At the axilla, reduction was -0.40 and rebound was 0.31 (P = .10). The differences in C acnes burden between pretreatment and 1-week counts at all sites were not statistically significant., Conclusion: A significant decrease in C acnes burden occurred after BPO application but was not permanent. Significant rebound occurred just 1 week later., (Published by Elsevier Inc.)