US police officers were seen joking as they watched footage of a 73-year-old dementia sufferer whose shoulder was said to have been dislocated during her arrest.

Video released by Karen Garner’s lawyer, shows officers watching the bodycam images of her arrest, and one of them asking “ready for the pop?” as her shoulder is pulled.

Ms Garner was detained on 26 June last year after she walked out of a Walmart in Colorado without paying for $14 (£10) worth of items.

Her lawyer says her elbow was fractured and shoulder dislocated during her arrest.

Back at the police station, officer Austin Hopp had showed fellow officers Ms Garner’s arrest – and as they watch, they fist-bump one another.

“Ready for the pop? Hear the pop?” one of the male officers says at one point, referring to Ms Garner’s shoulder.

A female officer, who helped during the arrest then says: “I hate this.”

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The video shows her pull her hat over her eyes while the male officer says “I love it”.

Video from inside Ms Garner’s nearby holding cell shows her slumped over, handcuffed to a bench.

She appears frail and confused and repeatedly says “I want to go home”.

During her arrest, Ms Garner – who suffers from dementia and sensory aphasia, which impairs her ability to verbally communicate and understand – was held against the bonnet of a patrol car in Loveland, about 50 miles north of Denver, with her handcuffed left arm bent up behind her head.

A lawsuit has now been filed against officer Hopp, other officers and the city of Loveland. It also alleges Ms Garner received no medical care for about six hours after she was taken to jail.

The suit comes amid a national reckoning over the use of force by US police against people – including African Americans and those with mental and physical health conditions.

On the police station video, officer Hopp says he is a little worried that Ms Garner is “like senile and stuff”.

Several times, he and the other officers say she fought with police and that she got her handcuffs halfway off.

Police put Hopp on leave after the lawsuit was filed and announced they would conduct an internal investigation.

Soon after, the district attorney’s office announced the arrest of Ms Garner would be investigated by a team of outside law enforcement agencies.

The city of Loveland has also said it will conduct a review.

Loveland police declined to comment on the video footage, pending the results of official investigations into the incident.

“Independent comment from the Loveland Police Department (LPD) would not be appropriate at this time,” it said in a statement.

“LPD has faith in the due process that this investigation allows for.”

Sarah Schielke, the lawyer representing Ms Garner and her family, said the latest video footage needed to be released to force the department to change.

“If I didn’t release this, the Loveland Police’s toxic culture of arrogance and entitlement, along with their horrific abuse of the vulnerable and powerless, would carry on, business as usual.

“I won’t be a part of that,” she said.