'Little People, Big World': Tori and Zach Roloff Say Son Is Not Progressing After Leg Surgery (Exclusive)

Following their son's leg surgery, the 'Little People, Big World' stars worry about his lack of improvement.

Jackson's had his leg surgery, but the worrying hasn't stopped for his mom and dad. In a new clip from the next episode of Little People, Big World, shared exclusively with ET, Tori and Zach Roloff are voicing their concerns after their firstborn isn't showing improvement following his leg surgery six months earlier. 

"There is legitimately something wrong," Tori tells viewers. "He isn’t progressing like they said that he would."

Considering the youngster's lack of progress and complaints of pain, the couple made a doctor's appointment to "make sure that there’s no actual structural damage," Tori says, "and it's just his body’s having a harder time recovering."

As Zach tells his mom, Amy Roloff, "If something isn’t healing right or growing right, I want to adjust -- especially before this new baby comes." The couple has since welcomed their third child together, a son named Josiah, who was diagnosed with achondroplasia like his dad and siblings

During a previous episode, Tori explained that Jackson's procedure involved putting plates on the growth plates of his legs to "hopefully slow down the growth and allow the bones to even out." 

In May, Jackson celebrated his fifth birthday, but his parents have not shared any further updates on his surgery recovery. 

Little People, Big World airs Tuesdays at 9 p.m. ET/PT on TLC.