After Hill’s departure, Rob Reiner decided to direct Misery himself. And when it came time to call “Action!” on the hobbling scene, he might’ve regretted changing it, as the smashing of ankles required a bit more special effects magic than simply lopping off a fake foot.
Effects guru Howard Berger was tasked with making the ghastly moment a reality. And per Berger’s detailed account of the hobbling to Yahoo! Entertainment, the effect was every bit as complicated to produce as you’d imagine, particularly as Reiner wanted to shoot parts of the scene in extreme close-up. To make the moment work, Berger and his team first molded gelatin casts of James Caan’s legs, then fitted each with wire armatures that would hold the false ankle at an angle, simulating the breakage after Bates’ sledgehammer made contact with the molds.
The problem was that after several takes of the scene, the armatures were no longer working, leaving the prosthetic foot to dangle freely instead of bending awkwardly. Per that Yahoo! piece, Berger claims he fixed the issue by pulling the ankle to a freakish angle himself with fishing wire. “I went to the special effects guy, and I grabbed monofilament and sewed it through the foot. And I was right off the corner of the bed, so when Kathy hit it, I pulled the fishing line as tight as I could, and it would just keep the foot there the whole time.”
However Reiner, Berger, and the rest of the Misery team brought the scene to life, it remains one of the most vivid, unshakably realistic depictions of onscreen violence from the pre-CGI era. And the horrifying end result is a big part of why Misery continues to rank among the best of Stephen King adaptations.