Loss of JSW is a hallmark of knee OA structural progression, and knee replacement (KR) is considered by regulatory agencies as a hard clinical endpoint in knee OA DMOAD clinical trials. There has been limited longitudinal investigation of JSW trajectories and their association with the risk of KR, however. In addition, identification of predictors of worse vs. better JSW loss trajectories may help identify potential targets for therapeutic interventions and may also be useful for selecting more homogenous study populations.

Knee pain is common, with more than 30% to 45% of middle-aged and older adults having symptomatic osteoarthritis, and 25% to 40% of younger adults having patellofemoral pain syndrome. Components of a detailed history include time of onset; pain duration, quality, and localization; trauma/mechanism of injury; swelling; popping/clicking; aggravating and alleviating factors; sports activities; and limitations to current activity. The physical examination for evaluating knee pain involves five overall components: inspecting the joint for obvious abnormalities, palpating the joint to identify effusion or points of tenderness that may be the source of the pain; testing active and passive range of motion; testing strength; and performing specialized maneuvers that evaluate specific knee joint structures. These maneuvers are most accurate when performed in combination, rather than relying on one specific maneuver to make the diagnosis. In addition to these five examination components, imaging should be obtained if appropriate, with plain radiography typically being the first step. With traumatic injuries, clinical decision rules such as the Ottawa Knee Rule can determine if radiography is needed to detect fractures or other injuries that may require referral. Additional evaluations can include arthrocentesis when joint effusion is present, optimally guided by point-of-care ultrasonography when available, and laboratory testing if infection or inflammatory disorders are suspected.

Eosinophilic fasciitis (EF) is a rare connective tissue disorder characterized by symmetrical or asymmetrical skin induration, fascial inflammation, and peripheral eosinophilia. We report the case of a middle-aged man presenting with left knee pain and swelling, progressive skin induration and pigmentation changes on the thigh and trunk. Blood workup showed peripheral eosinophilia and weakly positive PM-Scl-100 antibodies. MRI demonstrated fascial thickening with subcutaneous edema and fluid tracking along fascial planes, as well as a moderate knee effusion. Muscle biopsy confirmed eosinophilic fasciitis without muscle involvement. He was treated with high-dose prednisolone, methotrexate as a steroid-sparing agent, and adjunctive bone and infection prophylaxis, with marked clinical improvement at follow-up. This case highlights the diagnostic challenges in atypical presentation of eosinophilic fasciitis in the presence of overlap autoantibodies. Careful clinicopathological correlation is critical to exclude other differentials as EF can mimic systemic sclerosis or myositis. Biopsy can improve diagnostic certainty particularly when encountering auto-antibodies that have some association with other diagnoses.