Lethbridge police say the officer had been investigating a hit-and-run complaint in December and began speaking with the 16-year-old youth.
The officer believed the teen had been drinking and arrested him for public intoxication, but they say there was a struggle.
Const. Norman Smith, 33, is charged with assault causing bodily harm and unlawful confinement and is scheduled to appear in court Sept. 9.
Smith, a four-year veteran, has been relieved from duty with pay pending the outcome of the case.
Lethbridge police say the investigation was completed by their professional standards unit and was forwarded to the Crown for review before the charges were laid.
Police Chief Tom McKenzie says he trusts all of his officers to act professionally.
"While it's concerning and always is that there's complaints or allegations against our members, I have complete confidence and trust in the professionalism of our men and women in this service to complete their duties and to provide community safety first and foremost to the people that we serve and to serve them in a way that is professional and that maintains their confidence and their trust in our police service."
Smith was seriously injured in February 2011 when he tried to arrest two men on Lethbridge's south side. He had to be taken to a Calgary hospital.
Smith had a fractured skull, bleeding on the brain, a broken nose and cheekbone and several cuts. He was initially taken to hospital in Lethbridge, but was transferred to Calgary for further treatment.
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