Police spokeswoman Marinda Stoltz said Pistorius had asked Memory to leave and slammed the door. A wooden panel then dislodged from the door and injured her leg. Memory laid a charge with the police, and he was arrested.
Pistorius spent the night at the Boschkop police station and was released the next day with a warning.
Frans Stander, the estate's general manager, this week spoke of his shock at the arrest.
"Oscar is the most decent man you will ever meet in your life. He treats everyone with so much respect and I have never received a complaint about him since his been living here, that's why I was shocked at what had happened," he said.
Estate security guards praised the Blade Runner for being down to earth and helping out whenever he could.
Stander added that although Pistorius had thrown numerous parties since he moved in, all of them had been peaceful.
"His parties are loved by everyone, even the old couples at the estate look forward to going to them."
When asked about the incident, Stander said Memory had probably been drunk.
"At parties, alcohol always flows freely, and Memory had a lot to drink. She hit a (stormwater) drain on her way out of the estate," he added.