Joint Fluid Proteome after Anterior Cruciate Ligament Rupture Reflects an Acute Posttraumatic Inflammatory and Chondrodegenerative State.

OBJECTIVE: The purpose of this study was to evaluate changes in the synovial fluid proteome following acute anterior cruciate ligament (ACL) injury. DESIGN: This study represents a secondary analysis of synovial fluid samples collected from the placebo group of a previous randomized trial. Arthrocentesis was performed twice on 6 patients with an isolated acute ACL tear at a mean of 6 and 14 days postinjury. Synovial fluid was analyzed by a highly multiplexed assay of 1129 proteins (SOMAscan version 3, SomaLogic, Inc., Boulder, CO). Pathway analysis using DAVID was performed; genes included met 3 criteria: significant change between the 2 study time points using a paired t test, significant change between the 2 study time points using a Mann-Whitney nonparametric test, and significant Benjamini post hoc analysis. RESULTS: Fifteen analytes demonstrated significant increases between time points. Five of the 15 have been previously associated with the onset and/or severity of rheumatoid arthritis, including apoliopoprotein E and isoform E3, vascular cell adhesion protein 1, interleukin-34, and cell surface glycoprotein CD200 receptor 1. Chondrodegenerative enzymes and products of cartilage degeneration all increased over time following injury: MMP-1 (P = 0.08, standardized response mean [SRM] = 1.00), MMP-3 (P = 0.05, SRM = 0.90), ADAM12 (P = 0.03, SRM = 1.31), aggrecan (P = 0.08, SRM = 1.13), and CTX-II (P = 0.07, SRM = 0.56). Notable pathways that were differentially expressed following injury were the cytokine-cytokine receptor interaction and osteoclast differentiation pathways. CONCLUSIONS: The proteomic results and pathway analysis demonstrated a pattern of cartilage degeneration, not only consistent with previous findings but also changes consistent with an inflammatory arthritogenic process post-ACL injury.

Evaluation of meniscal extrusion with posterior root disruption and repair using ultrasound.

BACKGROUND: Ultrasound techniques have been utilized for detection of discrete meniscus tears and extrusion. Meniscal extrusion is associated with increased contact pressure and decreased contact area contributing to the advancement of knee osteoarthritis. The purpose of this biomechanical study was to detect meniscal extrusion using a clinically available, portable ultrasound device. And further, to show that extent of injury and a weight-bearing state correlate with amount of extrusion. METHODS: A portable, hand-held ultrasound was utilized to image the lateral meniscus in association with (1) an intact posterior root attachment, (2) a 50% cut, (3) a 100% cut, and (4) repaired posterior root attachment. Images were obtained in an unloaded condition, and again under a static, physiologic (70kg) axial load for above injury levels, and again following repair. RESULTS: Significant differences in extrusion were noted between the intact and both the 50% cut (p=0.028) and 100% cut groups (p<0.001) all in the loaded position. No significant difference was found in extrusion between intact state and repaired posterior root in the axially loaded position (p=0.174). Both load (p=0.003) and injury level (p=0.005) had significant effects on the mean extrusion of the lateral meniscus. CONCLUSION: Sectioning of the lateral meniscus posterior root will produce significantly increased lateral extrusion of the meniscus under physiologic loads. Unlike MRI evaluation, weight-bearing ultrasound images allow a functional assessment of meniscus extrusion. Trans-tibial posterior root repair can restore the lateral meniscus position and integrity. CLINICAL RELEVANCE: This weight-bearing ultrasound technique can be an important assessment tool for complete evaluation of meniscus injuries.