A teenager with pain in a single knee and a limp A teenage boy presents with knee discomfort and a limp after a recent fall, describing intermittent pain in the knee going back couple of months. How should he be investigated and what treatment will he need? Case presentation History A 15-year-old boy presents with still left knee discomfort and a limp one week after dropping from his bicycle.In a post hoc analysis, the primary efficacy end point and the principal safety end point were combined to provide a composite end stage of the net rate of adverse clinical events, which was 4.8 percent in the cangrelor group in comparison with 6.0 percent in the clopidogrel group . Adverse Events The rate of adverse events linked to treatment was related in the cangrelor and clopidogrel groups ; 0.5 percent of the adverse events in the cangrelor group and 0.4 percent of those in the clopidogrel group resulted in discontinuation of the study drug . There have been significantly more cases of transient dyspnea with cangrelor than with clopidogrel . Subgroup Analyses The reduction in the primary efficacy end point with cangrelor was consistent across multiple subgroups, with no significant interactions with baseline variables except for status regarding a history of peripheral-artery disease .