Kym Johnson is the partner of Hines Ward on Dancing With The Stars and the pair are among the 4 remaining couples and are in the semi-finals of the competition.  The 2 were rehearsing for Monday night's live show and injured herself during practice and was taken by ambulance to a local hospital.  Her publicist says that Kym

was taken to (the) hospital for precautionary measures (thehollywoodgossip.com)

According to Extra tv

Johnson was taken out on a stretcher with an oxygen mask on her face

If she is unable to perform on Monday night, Hines Ward will be paired with another professional dancer from the show that has been previously voted off.  Dancing With The Stars returns Monday evening at 7 on KLTV 7.

From Extra tv

UPDATE: The "DWTS" production released this statement regarding Johnson's condition. "Kym Johnson was admitted to the hospital today immediately after falling and injuring her neck during practice. After several tests, she was cleared by the medical staff, though she is bruised, sore and currently wearing a neck brace. Kym plans to continue with Hines Ward in the competition and resume rehearsals as soon as possible."