Kozak was taken to hospital in an ambulance last Thursday after sustaining the severe injury to his right leg in an innocuous training-ground challenge with Clark.
"He's had his treatment and hopefully he'll come back stronger and all the lads are thinking of him," Clark told the Birmingham Mail.
"Hopefully he'll make a full recovery. We were playing a possession game and it was a clash of legs. No-one expected it and we thought he was going to get back up. The physio came on and knew it was a bad injury.
"I didn't sense anything was wrong and I don't think anyone did. At the time people thought it was a normal challenge.
''I don't know if it was the impact or the way his leg went but it was innocuous and no-one expected it to be as bad."