QC Lab Tech was getting #4 Kiln Lime sample @ approx 11 PM & slipped going into NW corner doorway. She later reported her rt knee was sore & continued working throughout her schedule w/o incident. On 1/10/2012 she requested a diagnostic exam to check it out & a strain was diagnosed w/o any restrictions. Later PT was requested began on 1/18/2012 making incident reportable.