Section I: The Problem of Post-Traumatic Arthritis -- Arthritis that Develops after Joint Injury: Is it Post-Traumatic Arthritis or Post-Traumatic OsteoArthritis? -- Post-Traumatic Arthritis: Definitions and Burden of Disease -- Arthritis after Joint Injury: The Military Experience -- Section II: Experimental Models of Joint Injury -- In Vitro Cartilage Explant Injury Models -- Animal Models of Meniscal Injury in Post-Traumatic Arthritis.-Anterior Cruciate Transection/Disruption Models of Posttraumatic Arthritis -- Closed Joint ACL Disruption Murine Model of PTA -- Whole Joint Models of Articular Injury and Articular Fracture -- Instability: Dynamic Loading Models -- Survey of Animal Models in Post-Traumatic Arthritis: Choosing the Right Model to Answer the Right Question -- Section III: Peri-articular Tissue Response to Joint Injury -- The Response of Cartilage to Injury -- The Response of Subchondral Bone to Injury -- Genetic Variability in the Response to Injury -- Aging and Post-Traumatic Arthritis.-Potential Mechanisms of PTA: Cell Death -- Potential Mechanisms of PTA: Inflammation -- Potential Mechanisms of PTA: Oxidative Stress -- Potential Mechanisms of PTA: Alterations in Joint Loading -- Section IV: Clinical Assessment and Treatment of Patients with Joint Injury -- Imaging Specific to Cartilage Injury -- Outcomes of ACL Injury: The MOON Consortium -- Current Treatment and Outcomes of Intra-articular Fractures -- Non-arthroplasty Treatments for PTA in the Lower Extremity -- Results of Arthroplasty in Post-Traumatic Arthritis -- Section V: Developing and Future Assessment and Therapies -- Measurement of Severity of Injury after Articular Fracture and Correlation with Post-Traumatic Arthritis Development -- Biomarkers of PTA -- Potential Targets for Pharmacologic Therapies for Prevention of PTA.- Stem Cells Therapies for Post-Traumatic Arthritis -- Unanswered Questions and Future Directions.