Faculty Bibliography

BACKGROUND:Alterations in periarticular lipid composition are implicated in musculoskeletal diseases, yet short-term reliability of MRI-based triglyceride composition mapping in the knee is not fully established. PURPOSE/OBJECTIVE:To evaluate 1-week repeatability of proton-density fat fraction (PDFF) and triglyceride fatty-acid composition-saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA)-in periarticular knee tissues. STUDY TYPE/METHODS:Prospective. POPULATION/METHODS:). FIELD STRENGTH/SEQUENCE/UNASSIGNED:3T; 12-echo 3D spoiled gradient-echo acquisition for chemical shift-encoded fat quantification and a proton density-weighted SPACE sequence for segmentation (0.6 mm isotropic). ASSESSMENT/RESULTS:Participants underwent repeated MRI 1 week apart. Femoral and tibial bone marrow, patella, Hoffa's fat pad, prefemoral fat pad, quadriceps fat pad, posterior fat pad, and subcutaneous adipose tissue were segmented and rigidly aligned. Voxelwise spectral fitting was used to estimate PDFF and fatty acid composition, including SFA, MUFA, and PUFA components. Repeatability metrics included bias, within-subject standard deviation (wSD), within-subject coefficient of variation (wCV%), coefficient of repeatability, and intraclass correlation coefficient (ICC). STATISTICAL TESTS/METHODS:Paired t-tests assessed systematic differences (α = 0.05); ICCs used a two-way random-effects, absolute-agreement model (ICC(2,1)). RESULTS:PDFF showed lowest variability across all regions (wCV: 1.5%-5.9%; ICC: 0.33-0.96). SFA demonstrated similar stability (wCV: 2.4%-12.6%; ICC: 0.19-0.87). MUFA exhibited anatomy-dependent reliability (wCV: 4.1%-21.1%; ICC: 0.17-0.97), with highest repeatability in subcutaneous adipose tissue (ICC: 0.97) and Hoffa's fat pad (ICC: 0.85). PUFA displayed the greatest variability (wCV: 3.6%-52.8%; ICC: 0.10-0.94), with the greatest instability in periarticular fat pads. No paired comparisons were significant (all p > 0.05; range p = 0.14-0.98). Regional ordering remained consistent across sessions. DATA CONCLUSION/CONCLUSIONS:A 12-echo chemical shift-encoded MRI protocol provides repeatable PDFF and SFA measurements over 1 week. MUFA reliability varies by tissue, while PUFA remains least stable. EVIDENCE LEVEL/METHODS:2 (Prospective cohort). TECHNICAL EFFICACY STAGE/UNASSIGNED:2 (Reproducibility/feasibility evaluation).

This study evaluates the repeatability of a 3D simultaneous

BACKGROUND:Inflammatory biomarkers in an injured knee have been shown to predict outcomes, yet the role of the subsequent systemic inflammatory response to injury remains poorly understood. PURPOSE/OBJECTIVE:To investigate whether synovial fluid (SF) biomarkers from the contralateral uninjured knee could predict long-term patient-reported outcomes (PROs) for the operative knee in patients undergoing arthroscopic knee surgery. STUDY DESIGN/METHODS:Case series; Level of evidence, 4. METHODS:This retrospective analysis included patients undergoing knee SF aspiration before arthroscopy with ≥8 years of follow-up. SF was aspirated from both the injured and healthy contralateral knees, and concentrations of 10 pro- and anti-inflammatory biomarkers were quantified. Patients completed visual analog scale (VAS) for pain score, Lysholm, Tegner, and Knee injury and Osteoarthritis Outcome Score Physical Function Short Form (KOOS-PS) surveys preoperatively and at the final follow-up. Stepwise linear regression was performed to identify the most significant predictor(s) of PRO scores utilizing log-normalized contralateral biomarker concentration, age, body mass index, injury type, and Outerbridge grade as covariates. Concentrations from the contralateral knee were also compared with the injured knee to assess for correlations. RESULTS:= .006) score at the final follow-up. Contralateral concentrations of monocyte chemotactic protein 1, macrophage inflammatory protein 1β, vascular endothelial growth factor, and TIMP-1 were correlated with levels in the operative knee but at significantly lower concentrations. CONCLUSION/CONCLUSIONS:SF biomarker levels in the contralateral uninjured knee at the time of arthroscopy were predictive of long-term outcomes for the operative knee. Increased levels of pro-inflammatory biomarkers were predictive of worse outcomes, while anti-inflammatory cytokines predicted improved scores. These results suggest that unilateral knee injury can result in a broader systemic inflammatory response that influences long-term outcomes in patients.

BACKGROUND:The knee's inflammatory response to ligamentous, meniscal, and cartilage injuries is complex and incompletely understood, particularly in the setting of concomitant injuries. Recent research has highlighted the potential utility of synovial fluid biomarker analysis in identifying factors involved in the progression of posttraumatic osteoarthritis. PURPOSE/OBJECTIVE:To investigate if unique patterns of knee injury are associated with distinct synovial fluid biomarker profiles at the time of surgical intervention. STUDY DESIGN/METHODS:Cross-sectional study; Level of evidence, 3. METHODS:Patients undergoing arthroscopic knee surgery were prospectively enrolled and asked to complete the Lysholm Knee Scoring Scale and visual analog scale for pain preoperatively. Synovial fluid was aspirated from the operative knee before surgical incision, and the concentrations of 10 biomarkers of interest were quantified. Patients with intraoperative evidence of articular cartilage, meniscal, and/or anterior cruciate ligament (ACL) injury were identified and included for subsequent analysis. Biomarker concentrations were log-normalized and standardized. Principal component analysis (PCA) was performed using biomarker variables to reduce dimensionality and extract key patterns. Multivariable linear regression for each retained principal component (PC) was performed with the predictors of age, sex, body mass index, symptom duration, ACL injury, meniscal injury, and Outerbridge grade. A separate regression analysis was performed to assess relationships between PCs and patient-reported outcomes controlling for the same variables. RESULTS:= .001; β = -.199). CONCLUSION/CONCLUSIONS:Cartilage lesions exhibited a synovial fluid inflammatory profile distinct from ACL and meniscal injury at the time of knee arthroscopy. While ACL and meniscal injuries displayed a pro-inflammatory phenotype, more severe cartilage lesions were associated with a reduced presence of anti-inflammatory markers. The pro-inflammatory phenotype also independently correlated with worse baseline knee function. These findings contribute to the understanding of the pathophysiology of ligamentous, meniscal, and cartilage injuries and may aid in the identification of pathology-specific treatments to help alter the natural history of disease.

Cellular senescence is an irreversible state of cell cycle arrest with a complex role in tissue repair, aging, and disease. However, inconsistencies in identifying cellular senescence have led to varying conclusions about their functional significance. We developed a machine learning-based approach that uses nuclear morphometrics to identify senescent cells at single-cell resolution. By applying unsupervised clustering and dimensional reduction techniques, we built a robust pipeline that distinguishes senescent cells in cultured systems, freshly isolated cell populations, and tissue sections. Here we show that this method reveals dynamic, age-associated patterns of senescence in regenerating skeletal muscle and osteoarthritic articular cartilage. Our approach offers a broadly applicable strategy to map and quantify senescent cell states in diverse biological contexts, providing a means to readily assess how this cell fate contributes to tissue remodeling and degeneration across lifespan.

BACKGROUND:Synovial fluid (SF) biomarkers demonstrate time-dependent variation after acute knee injury, and it is postulated that persistently elevated inflammatory markers may mediate worse long-term outcomes. PURPOSE/OBJECTIVE:This study investigated the relationship between biomarkers in SF at the time of meniscectomy and long-term patient-reported outcomes in patients with acute versus chronic meniscal injuries. STUDY DESIGN/METHODS:Cohort study; Level of evidence, 3. METHODS:This retrospective analysis included patients who underwent knee SF aspiration on the day of arthroscopic meniscectomy between October 2011 and October 2020 with minimum 4-year follow-up. SF aspirated from the operative knee was analyzed for 10 pro- and anti-inflammatory biomarkers. Patients completed the visual analog scale for pain, Lysholm Knee Questionnaire, Tegner Activity Scale, and Knee injury and Osteoarthritis Outcome Score-Physical Function Short-form (KOOS-PS) before surgery and at follow-up. Patients were categorized as having acute (<6 weeks) or chronic (>1 year) symptoms. K-means clustering analysis was performed using biomarker levels to group patients into distinct cohorts. RESULTS:= .020) than the low-inflammation cohort. CONCLUSION/CONCLUSIONS:In patients with chronic meniscal injury, those with a more proinflammatory SF biomarker profile at the time of meniscectomy had worse outcomes than those who had a low inflammatory profile. In acute meniscal injuries, most patients demonstrate a high inflammatory profile, which was not associated with a difference in long-term outcomes.

PURPOSE/OBJECTIVE:To evaluate knee intra-articular cytokine concentrations in patients undergoing isolated meniscectomy and determine if these concentrations are associated with clinical outcomes. METHODS:Concentrations of ten biomarkers were quantified in synovial fluid aspirated from the operative knees of patients who underwent isolated meniscectomy from 10/2011-12/2019. Patients completed a survey at final follow-upincluding VAS, Lysholm, Tegner, and KOOS Physical Function Short Form (KOOS-PS). Failure was defined as subsequent TKA or non-achievement of the Patient Acceptable Symptom State (PASS) for knee pain defined as VAS > 27/100. Regression analysis investigating the relationship between cytokine concentrations and failure was performed. RESULTS:[25.5, 32.4], and a mean follow-up of 8.0 ± 2.2 years. There were no demographic or clinical differences between failures (n = 41) and non-failures (n = 59) at baseline. Monocyte Chemotactic Protein 1 (MCP-1) concentration was significantly higher in failures than in non-failures (344.3 pg/ml vs. 268.6 pg/ml, p = 0.016). In a regression analysis controlling for age, sex, BMI, symptom duration, length of follow-up, and ICRS grade, increased MCP-1 was associated with increased odds of failure (p = 0.002). CONCLUSIONS:The concentration of MCP-1 on the day of arthroscopic meniscectomy was predictive of failure as defined by an unacceptable pain level at intermediate- to long-term follow-up. This finding may help identify patients at high risk for poor postoperative outcomes following isolated meniscectomy and serve as a target for future postoperative immunomodulation research.

Peptides that increase pro-reparative responses to injury and disease by modulating the functional organization of hyaluronan (HA) with its cell surface binding proteins (e.g., soluble receptor for hyaluronan-mediated motility [RHAMM] and integral membrane CD44) have potential therapeutic value. The binding of RHAMM to HA is an attractive target, since RHAMM is normally absent or expressed at low levels in homeostatic conditions, but its expression is significantly elevated in the extracellular matrix during tissue stress, response-to-injury, and in cancers and inflammation-based diseases. The HA-binding site in RHAMM contains two closely spaced sequences of clustered basic amino acids, in an alpha-helical conformation. In the present communication, we test whether an alpha-helical conformation is required for effective peptide binding to HA, and competitive disruption of HA-RHAMM interaction. The HA-binding RHAMM-competitive peptide P15-1, identified using the unbiased approach of phage display, was examined using circular dichroism spectroscopy and the conformation-predictive AI-based AlphaFold2 algorithm. Unlike the HA-binding site in RHAMM, peptide P15-1 was found to adopt irregular conformations in solution rather than alpha helices. Instead, our structural analysis suggests that the primary determinant of peptide-HA binding is associated with a specific clustering and spacing pattern of basic amino acids, allowing favorable electrostatic interaction with carboxylate groups on HA.

BACKGROUND:The purpose of the present study was to evaluate the relationships of the concentrations of pro- and anti-inflammatory biomarkers in the knee synovial fluid at the time of arthroscopic partial meniscectomy (APM) to long-term patient-reported outcomes (PROs) and conversion to total knee arthroplasty (TKA). METHODS:A database of patients who underwent APM for isolated meniscal injury was analyzed. Synovial fluid had been aspirated from the operatively treated knee prior to the surgical incision, and concentrations of pro- and anti-inflammatory biomarkers (RANTES, IL-6, MCP-1, MIP-1β, VEGF, TIMP-1, TIMP-2, IL-1RA, MMP-3, and bFGF) were quantified. Prior to surgery and again at the time of final follow-up, patients were asked to complete a survey that included a visual analog scale (VAS) for pain and Lysholm, Tegner, and Knee injury and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS) questionnaires. Clustering analysis of the 10 biomarkers of interest was carried out with the k-means algorithm. RESULTS:Of the 82 patients who met the inclusion criteria for the study, 59 had not undergone subsequent ipsilateral TKA or APM, and 43 (73%) of the 59 completed PRO questionnaires at long-term follow-up. The mean follow-up time was 10.6 ± 1.3 years (range, 8.7 to 12.4 years). Higher concentrations of individual pro-inflammatory biomarkers including MCP-1 (β = 13.672, p = 0.017) and MIP-1β (β = -0.385, p = 0.012) were associated with worse VAS pain and Tegner scores, respectively. K-means clustering analysis separated the cohort of 82 patients into 2 groups, one with exclusively higher levels of pro-inflammatory biomarkers than the second group. The "pro-inflammatory phenotype" cohort had a significantly higher VAS pain score (p = 0.024) and significantly lower Lysholm (p = 0.022), KOOS-PS (p = 0.047), and Tegner (p = 0.009) scores at the time of final follow-up compared with the "anti-inflammatory phenotype" cohort. The rate of conversion to TKA was higher in the pro-inflammatory cohort (29.4% versus 12.2%, p = 0.064). Logistic regression analysis demonstrated that the pro-inflammatory phenotype was significantly correlated with conversion to TKA (odds ratio = 7.220, 95% confidence interval = 1.028 to 50.720, p = 0.047). CONCLUSIONS:The concentrations of synovial fluid biomarkers on the day of APM can be used to cluster patients into pro- and anti-inflammatory cohorts that are predictive of PROs and conversion to TKA at long-term follow-up. LEVEL OF EVIDENCE/METHODS:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.