A man hurt while being arrested waited eight hours for treatment despite custody staff being told 20 times of his injury, the police watchdog found.
The 41-year-old fractured his kneecap during a struggle with officers at Falkirk police station on April 28 last year.
He had gone to the station after an incident at a pub in the town centre.
During his arrest he was taken to the ground by an officer, who took hold of his arm and swept his legs away.
The case was referred to the Police Investigations and Review Commissioner (Pirc), who found the man was given a wheelchair and crutches to help him get around but was not examined by a custody nurse.
He and the arresting officer made custody staff aware of the injury at least 20 times during the eight hours he spent in detention, Pirc said.
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It was only on his release he went to hospital, where it was found he had a fractured kneecap.
Pirc said the record of the man's time in custody was not accurately kept.
The report said: "As there was no CCTV footage of the entire incident and there are inconsistencies in the police witness statements, together with the fact that the man himself cannot provide a clear recollection of events, it cannot be confirmed if the level of force used by the arresting officer was proportionate or justified."
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The commissioner recommended Police Scotland remind custody officers that in such cases detainees should be examined by medical staff as soon as possible.
They should also accurately record all interactions with people in police custody, including complaints of injuries and any medication provided to them.
