DWTS' Contestant Lindsey Stirling Has Injured Her Knee and May Be Unable to Compete

Dancing With the Stars front-runner Lindsey Stirling has injured herself for the second time this season -- and it remains unclear whether or not she'll be able to perform during Monday's show. "Lindsey injured her knee during camera blocking rehearsal Sunday morning while working on a number with the troupe," a DWTS source told PEOPLE, who explains that the girls from the troupe are standing in for her at rehearsal and pro Sharna Burgess, who was eliminated alongside her partner Derek Fisher ea...