Why Kaley Cuoco's Penny Is Missing From Two The Big Bang Theory Season 4 Episodes

The five original main cast members on "The Big Bang Theory" — namely, Jim Parsons, Johnny Galecki, Simon Helberg, Kunal Nayyar, and Kaley Cuoco as Sheldon Cooper, Leonard Hofstadter, Howard Wolowitz, Raj Koothrappali, and Penny, respectively — appear in basically every episode of the series, but there's one major exception. Cuoco, an avid horseback rider, got seriously injured during a ride in September 2010 — and as a result, she missed two episodes of the show's fourth season (specifically, the fifth and sixth episodes "The Desperation Emanation" and "The Irish Pub Formulation").

As Jessica Radloff details in her 2022 book "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," Cuoco was riding at a ranch outside of Los Angeles when the horse unexpectedly threw her ... and stepped on her left leg. (According to the book, she told talk-show host Ellen Degeneres of the incident, "I didn't feel anything, but then I looked and I'm like, 'Wow, my foot's facing me... that's not normal.'") Cuoco was rushed to a hospital, and as "The Big Bang Theory" creator Chuck Lorre told Radloff, it was a rough time for the series.

"That was the darkest, most frightening time in all twelve years," Lorre recalled. "Kaley could have lost her leg. It was a series of miracles that allowed us to get through that and for her to come out the other end of that healthy." Everything ended up okay — thanks in large part to Lorre's connections, which I'll circle back to momentarily — but it's worth noting that in Lorre's 309th vanity card on the series, Lorre introduced "new rules governing acceptable leisure activities for the cast of The Big Bang Theory," with the first being, "No friggin' horses. This includes those found on merry-go-rounds and in front of supermarkets."

For her part, Kaley Cuoco also told Jessica Radloff that the experience was terrifying ... partly because she signed a document before surgery agreeing that doctors could amputate her leg if they absolutely needed to. "Everything ended up fine, and I was up and working a week later, but the doctors acted like I was never going to walk again," Cuoco recalled, remarking that she understood that the experience was scary ... and was just glad it all worked out okay. "It's still too much for me to go into, and it sounded way worse than it was. And of course it was spiraling and everyone was freaking out, which I get. It scared people." 

Not only did Cuoco come out of this horrifying situation with her leg intact, she also had some bizarre priorities when she first woke up from her procedure. "My accident also happened when we were in the middle of one of our biggest contract negotiations," Cuoco told Radloff. "I don't know what possessed me to say this — and it is so f***ed up given how serious the injury was — but the minute I came out of recovery from surgery, I said to Johnny, 'Did the deal close?' And he said, 'Yeah, we got it.' It had closed while I was in surgery, and of all things, that's what was on my mind. So terrible."

So how did Chuck Lorre help Cuoco out during her genuinely scary medical emergency? As he recalled in the book, he was reeling over news of Cuoco's injury when he unexpectedly ran into a friend, Dr. Stephen Lombardo, who just so happened to work in a major orthopedic clinic at Cedars-Sinai Hospital. Lorre asked for the good doctor's assistance, which helped get Cuoco into surgery faster. "But it was an absolutely miraculous intervention that I ran into Dr. Steve on that golf course," Lorre mused. "Every time I see him, I say, 'Thank you! You saved Kaley! On a lesser level, you saved 'The Big Bang Theory'!'"

We all know that when actresses are pregnant, TV shows go to great lengths to hide their growing bellies ... and the same was true for Kaley Cuoco after her orthopedic surgery. Though she was cleared to return to work, she was in a boot, so Chuck Lorre and his team came up with a very amusing solution.

"She was a trooper," Johnny Galecki told Jessica Radloff in the book. "They put Kaley behind a lot of things on the set, like the couch or the bar, so you couldn't see the boot." So what bar was that? "We made her a bartender at The Cheesecake Factory to hide her injury!" Lorre laughed. "And she was a terrible bartender! We just wanted to keep her off her feet as much as possible. She's a terrific actress, but she also trains like a world-class athlete. She played competitive tennis early in her life, and she's ruthless about physical conditioning, which I think had a lot to do with her fast recovery."

According to Cuoco herself, there were a few other scenes that required some Hollywood trickery — like one with her on-screen dad Wyatt (Keith Carradine) in the season 4 episode "The Boyfriend Complexity." In a scene where Penny "storms" into her bedroom, Cuoco said the crew came up with something clever: "That is not me walking to my bedroom. That was the one instance where we used a body double for me because I had my boot on from the accident, so if you look closely, you can tell. They wanted me to storm out, but I wasn't able to walk that fast yet. And in all the scenes in that episode, if you pay close attention, I'm not moving. It's so brilliant. So the one time I had to really move, it was a body double." In another scene from that season, Cuoco says you can see a boot hidden in Penny's Wonder Woman costume if you pay close attention. Clearly, everyone was extremely lucky that Cuoco recovered ... and lucky, the only real outcome of her injury was a handful of funny anecdotes about filming.