EE WAS CALLED OUT OT WORK AT APPROX.10 PM TO REPAIR EAS4 AIRSLIDE. THIS REPAIR WORK REQUIRED HIM TO BE ON AND OFF HIS KNEES. THIS REPAIR WORK TOOK APPROX.12 HRS TO COMPLETE. HIS KNEE HAD START ED HURTING HIM ABOUT 5AM. WHEN THE JOB WAS COMPLETE HE WENT HOME AND ICED HIS LEFT KNEE, THINKING HE HAD JUST OVERWORKED IT. HE NOTICED HIS SUPERVISOR ON 8-14 THAT HIS KNEE STILL HURT AND A D