A Tennessee grandmother went to the hospital for what was supposed to be a routine knee replacement — but her family says a horrifying medication mix-up left her paralyzed from the chest down.

Glenda Dorton, 72, checked into Ascension Saint Thomas Hospital Midtown in Nashville on Friday for knee surgery.

Her family claims that while doctors were treating her pain, Dorton was mistakenly given potassium chloride instead of medication intended for an epidural, according to WSMV4.

Potassium chloride can be extremely dangerous when administered incorrectly. The drug was also previously used as part of Tennessee’s lethal-injection protocol, although the state has since changed the drugs used in executions.

Now, Dorton remains in the intensive care unit and is unable to move below her chest, according to her daughter-in-law, Kristina Dorton.

Her devastated family is waiting to learn whether the paralysis can be reversed.

The frightening case may not have been the only one connected to what happened inside the hospital.

Ascension Saint Thomas officials acknowledged that at least three other patients were affected by an undisclosed “event” at the facility.

The hospital has not publicly confirmed the family’s allegation that Dorton received potassium chloride by mistake, and officials have declined to release details about the other patients, citing privacy concerns.

Hospital president and CEO Dr. Shubhada Jagasia apologized for the harm suffered by patients.

“On behalf of our leadership and care teams, I am deeply sorry for the harm caused to our patients,” Jagasia said in a statement.

She added that hospital leaders have met with the affected families and are providing support, spiritual care and access to continued medical treatment.

For Dorton and her loved ones, however, the nightmare is far from over as doctors work to determine the full extent of the damage and whether she will ever regain movement.

The hospital is continuing to investigate exactly what happened.