How did chester keep his leg stiff on gunsmoke?

Dennis Weaver simply did it - he refused to wear any kind of device on the leg in fear that if he were to fall from a horse or something the leg could be injured if he couldn't bend it. He had an amazing concentration to walk like that the whole time he was on camera. He did say once that it took a while after he left Gunsmoke to not automatically limp whenever the director said "action".