The employee appeals the compensation judge’s finding that the employee did not sustain a work-related injury on October 11, 2006.  We affirm.

Patrick J. McLafferty, the employee, began working as a building maintenance worker for RS Eden, the employer, in January 2006.  The employee’s job duties varied, but he was generally responsible for the daily maintenance of the employer’s residential treatment facilities.  The employee worked primarily at the Eden House building but also worked at the Beatty Manor building on Thursdays.  The employee would also go to Beatty Manor on other days if emergency or other repairs were necessary.

The morning of October 11, 2006, the employee attended a coordinator’s meeting at Eden House.  The building manager of Beatty House and tenants of that facility also attended the meeting.  After the meeting, the employee testified he was asked by residents of Beatty House to remove an air conditioner from the television room because it was poorly insulated and cold air was entering the residence.  The employee spent the morning working at Eden House.  Sometime that morning, the employee testified he was instructed by Pam Lindgren, his supervisor, to measure the rooms at Beatty House in preparation for getting an estimate for new carpeting.  The employee also reminded Ms. Lindgren that he was planning to attend a Christmas party planning meeting in St. Paul after leaving Beatty House.

The employee testified that when he arrived at Beatty House he measured rooms for approximately one hour.  He then went to the television room, opened the window, removed the air conditioning unit and turned to set it on a table.  While turning, the employee stated, he twisted his foot causing his left knee to twist and bend and he fell to the floor with the unit still in his arms.  The employee testified he then pushed the air conditioning unit up onto a table.  The employee stated he injured his left knee in this incident, but was able to walk although he “hobbled a little but not real bad.”  (T. at 52.)

Immediately after this incident, the employee drove to St. Paul to attend the Christmas planning meeting.  During his drive to St. Paul, the employee noticed he had a headache.  The planning meeting was attended by six to eight people but the employee did not mention his injury to anyone.  After the meeting, the employee went home and told his wife what happened.  The employee testified his knee was then swollen and bruised and he had a severe headache.

The following morning, October 12, the employee spoke with Ms. Lindgren and told her he was not coming to work because he had a migraine headache.  The employee spoke to Ms. Lindgren again the following morning and was told he needed to get a doctor’s slip if he was to remain off work.  The employee then scheduled an appointment with his physician.

The employee saw Dr. Gregory Peters at the Allina Medical Clinic on October 13, 2006.  The employee reported an injury to his low back and left knee while lifting an air conditioning unit on October 11, 2006.  Dr. Peters diagnosed a low back injury with right lumbar radiculopathy and a left knee injury with possible torn medial meniscus.  The doctor ordered an MRI scan of the spine and left knee and restricted the employee’s work activities.  The scan of the employee’s left knee showed a tear of the posterior horn of the medial meniscus, significant cartilage loss along the medial tibial plateau and chondromalacia of the patella.

At trial, the employee’s wife testified that on the evening of October 12, 2006, she looked at her husband’s knees and saw the left knee was swollen.  She testified her husband told her this occurred at work while removing an air conditioner from a window.  Mrs. McLafferty testified she and her husband discussed whether he should report the injury and decided the employee should not report it until he saw a doctor.

Jennifer Gast, a program director for the employer, attended the Christmas party planning meeting in St. Paul at 2:00 p.m. on October 11, 2006.  Ms. Gast testified she observed the employee walk into the meeting and stated he was not limping.  The employee sat next to Ms. Gast during the one-hour meeting.  Ms. Gast testified the employee did not mention any injury to her or appear to be in any pain.

Jeff Robinson was a resident at Beatty Manor from August 16 to October 19, 2006, and at the residence every evening.  Mr. Robinson stated there were three air conditioning units in the residence one of which was in the TV room.  This was the air conditioning unit the employee stated he removed from the window on October 11, 2006.  Mr. Robinson testified that on that date, the air conditioning unit was not in the window because it was removed on September 28.  Mr. Robinson testified that on October 11 the air conditioning unit was on the floor in a corner of the television room.

In 2006, Pamela Lindgren was a program director for the employer.  Ms. Lindgren was the employee’s supervisor, she assigned his work and he reported directly to her.  Ms. Lindgren testified that on October 11 she did not direct the employee to go to Beatty Manor to measure the floors for new carpeting.  Ms. Lindgren stated the carpeting was then only two years old and was not scheduled to be replaced.  Ms. Lindgren further testified she did not direct the employee to go Beatty Manor and remove an air conditioning unit.  She testified the air conditioning units at Beatty Manor were removed on September 28, 2006.  Ms. Lindgren testified that in September, residents at Beatty Manor were complaining it was cold, so she directed the air conditioning units be removed and the heat turned on.  Finally, Ms. Lindgren testified she first heard from the employee that he sustained a personal injury on October 18, 2006.

Following the hearing, the compensation judge found the employee did not sustain a personal injury on October 11, 2006, and denied his claim for benefits.  The employee appeals.

The employee contends the compensation judge’s decision should be reversed because the decision fails to take into account the corroborating evidence submitted by the employee and the lack of such evidence submitted by the employer and insurer.  There was no evidence the employee had any prior traumatic injury or disability to his back, neck or knees prior to October 11, 2006.  The employee testified he was able to perform a very physical job with no difficulty for over nine months before his injury.  The employee’s testimony that he injured his back and left knee on October 11 was corroborated by the testimony of his wife.  Further, the records of Dr. Peters contain a history that the employee injured his low back and left knee while lifting an air conditioning unit on October 11, 2006.  Accordingly, the employee asserts he met his burden of proving a work injury by a preponderance of the evidence, and contends the compensation judge erred in denying his claim.

The employee has the burden of proving the employer’s liability for compensation for a personal injury arising out of and in the course of employment.  Minn. Stat. § 176.021, subd. 1.  Where a plaintiff proves a prima facie case and it is unrebutted by the defendant, the plaintiff has met the burden of proof.  Elk River Concrete Products Co., v. American Cas. Co., 268 Minn. 284, 129 N.W.2d 309 (1964).  In this case, there is evidence which, if accepted by the compensation judge, would support an award of benefits to the employee.  That evidence includes the testimony of the employee, the medical records of Dr. Peters, and the corroborating testimony of Ms. McLafferty.  The issue on appeal, however, is not whether the evidence will support a different result from that reached by the compensation judge but, rather, whether the findings of fact and order were clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.  Minn. Stat. § 176.421, subd. 1.  Substantial evidence supports the findings if, in the context of the entire record, they are supported by evidence a reasonable mind might accept as adequate.  Hengemuhle v. Long Prairie Jaycees, 358 N.W.2d 54, 59, 37 W.C.D. 235, 239 (Minn. 1984).

Three witnesses at trial contradicted the employee’s testimony regarding the details of his claimed injury.  Ms. Gast, a co-employee, saw the employee shortly after the alleged injury and testified the employee displayed no signs of injury or any altered gait.  Ms. Lindgren denied assigning the employee the task of measuring the floors for new carpet at Beatty Manor.  Ms. Lindgren and Mr. Robinson testified the air conditioning unit had been removed from the window before October 11.  This testimony constitutes substantial evidence supporting the compensation judge’s decision.

The employee makes numerous arguments as to why the testimony of Ms. Gast, Mr. Robinson, and Ms. Lindgren was not credible.  The employee contends Ms. Gast supported the position of the employer because of her employment relationship.  Mr. Robinson, the employee contends, had little or no recollection of other facts such as the names of other persons with whom he lived at the time or the name of the resident manager at Beatty Manor.  Although Mr. Robinson could not remember any of these facts, he remembered the date when the heat was allegedly turned on at Beatty Manor.  Finally, the employee contends Ms. Lindgren was acting as an advocate for her employer and not as a witness to events and her testimony contained numerous contradictions.

Assessment of the credibility of witnesses is the unique function of the trier of fact.  Brennan v. Joseph G. Brennan, M.D., 425 N.W.2d 837, 839-40, 41 W.C.D. 79, 82 (Minn. 1988).  The compensation judge found the testimony of Ms. Gast, Mr. Robinson, and Ms. Lindgren to be credible.  While the compensation judge may consider motives for a witness’s testimony, inconsistencies in a witness’s testimony, the likelihood of the truth of the testimony and any other factor affecting credibility, we find no basis in this case to reverse the judge’s credibility assessment.  Considering all of the evidence in the case, the record amply supports the compensation judge’s credibility assessments.  Accordingly, the decision of the compensation judge is affirmed.