Hip fracture patients in England and Wales are waiting up to 80 days to get rehabilitation treatment after leaving hospital, according to a survey of nearly 6,000 patients.
The Chartered Society of Physiotherapy said people face a "postcode lottery" over waits, with only one in five people being seen within a week.
It said the delay was putting people at increased risk of ill health and falls.
NHS England and NHS Wales both said they were working to improve care.
But what should be happening and what do you do if you or a loved one are left waiting for treatment?
What should happen?
Those who suffer the injury typically receive surgery and then days or weeks of rehab in hospital before being discharged.
NHS guidelines state that after surgery, patients should be offered rehabilitation once a day
But there are no guidelines for what happens after people leave hospital.
The CSP, the professional body for physiotherapists, said their rehab should quickly resume at home in order to ensure the best chances of recovery.
It said ideally there should be no break between rehab in hospital and home, but failing that the wait should be no more than a week.
But what actually happens?
The CSP says there is a "postcode lottery" over treatment, with only one in five people resuming their rehab within a week of leaving hospital.
It found there was an average wait of 15 days before receiving rehab at home.
The amount of rehabilitation patients received also varied greatly, its report found, with some getting less than one hour per week.
Ruth ten Hove, head of research and development at CSP, said the variation was a result of the different care plans set by individual clinical commissioning groups, which oversee rehabilitation care.
The CSP is now calling for guidelines to be established so that care is more consistent across England and Wales.
Why do the delays matter?
Hip fractures are usually caused by falls in elderly people who are frail, unfit and have at least one other long-standing condition, Ms ten Hove said.
A third of the those who suffer the fractures also have dementia, she said.
Without quick rehabilitation they are more likely to lose mobility and confidence and suffer illnesses related to being sedentary.
"They lose confidence very quickly. That puts them at risk of further falls, so they tend not to move around very much, which then puts them at risk of chest infections, deep vein thrombosis and a very high risk of depression.
"This is a population that really shouldn't be waiting for rehab."
'Complete loss of independence'
Iona Price's mother, Alice, died from a chest infection, aged 88, after she fractured her hip in 2012.
The condition is one of the risk factors faced by patients who do not receive continuous rehab after leaving hospital, the CSP said.
She had to wait almost four months for rehabilitation at home, her daughter said.
"During that time, she had to move into a nursing home and was completely dependent on others for her every need which soon led to depression," she said.
"Complete loss of independence aside, I can't help but think she would have made a much healthier recovery had her access to treatment been timely."
What should you do if you can't get treatment?
The CSP says people should first complain to their GP, a local patient support network, or the physiotherapy services in their hospital to get rehab.
Before rehab resumes, they should do exercises that focus on improving leg strength and balance, either with a friend or relative or on their own, depending on fitness levels.
Exercises can be as simple as walking, getting up and down from a chair or bed, or walking up and down stairs.
Furniture or other items at home that could potentially cause someone to trip up should be removed to reduce the risk of falls.
People who are worried about a friend or family member should make contact with local health services, including the person's GP.
What does the NHS say?
NHS England said: "Access to physiotherapy does vary across the country which is why NHS England is working with doctors to help them to provide better and more consistent care in all areas.
"This includes providing expert advice to local health bodies to reduce variation and improve care for patients."
The Welsh Government said: "Whilst we do not recognise these figures, we recognise the importance of receiving rehab at home as soon as possible after leaving hospital and expect all patients to be seen in a timely manner."