The employer and insurer appeal from the compensation judge’s determination that the employee sustained a work-related injury on March 22, 2013, and that the employee provided timely statutory notice of his injury.  We affirm.

The employee, Ghouse Jaffer, worked for the employer, Holiday Stationstores, Inc., as a sales associate.  He worked the overnight shift, typically beginning between 9:00 and 10:00 p.m. and ending at 6:00 a.m.  The employee always worked with a night manager, as the employer had a policy prohibiting an employee from working alone.

On March 22, 2013, after working on the sales floor until midnight, the employee began restocking.  Restocking required the employee to move product from the freezer to the refrigerated storage area of the store.  The employee testified he bent over to lift a tote box and collided with shelving in the freezer.  Several boxes were dislodged from an upper shelf and struck the employee on the left side of his upper neck and back, and on his left shoulder.  The employee testified he called out and the night manager Chris Cotner, known among the employees as C.W., came to assist him.  The employee described C.W. entering the freezer, noting the condition of the freezer as a mess, and assisting the employee to sit down.  The employee testified that C.W. brought the employee some Advil and a bottle of water, and directed the employee to sit for about 20 minutes.  The employee stated C.W. told him to finish his shift working behind the counter.  No injury report was filed regarding the incident at that time.

The employee was off work starting the following day due to previously scheduled eye surgery unrelated to the claimed work injury.  The surgery took place on April 10, 2013.  The employee was prescribed narcotic medication for post-surgical pain.

The employee returned to work on May 28, 2013, after being contacted by an assistant manager and told he was back on the work schedule.  The employee noted pain in his left shoulder on his first shift back to work when he removed a box from a high shelf in the storage area.  The employee testified he informed the assistant manager of his pain and that he had been struck by falling boxes on his last day of work before his eye surgery.  The employee was not certain of the date of his discussion with the assistant manager, but stated it was either on May 29 or 30, 2013.  No injury report was filed at this time.

On May 31, 2013, the employee sought medical care for his left shoulder from Dr. Asa Kim.  The employee reported left shoulder pain of 8 to 9 out of 10.  Dr. Kim noted the employee had limited range of motion and difficulty using his arm and that he had not had any particular issues with the left shoulder prior to the March 22, 2013, incident.  Dr. Kim diagnosed adhesive capsulitis and recommended conservative treatment in the nature of physical therapy and Vicodin for pain.  When his left shoulder pain did not abate, the employee was referred by his family physician to Dr. Joseph Nemanich at Twin Cities Orthopedics.  On July 1, 2013, Dr. Nemanich examined the employee and diagnosed left shoulder impingement.  X-rays showed mild degenerative changes in the AC joint.  Dr. Nemanich took the employee off work until July 8, 2013.  A subsequent MRI scan showed a full thickness rotator cuff tear.  Dr. Nemanich kept the employee off work and continued physical therapy.

After Dr. Nemanich took the employee off work on July 1, the assistant manager had the employee complete an incident report.  The employee stated he had been struck by falling boxes in the freezer that injured his left shoulder on March 21, 2013.  He indicated that C.W. had been informed of the incident at the time it occurred.  Subsequently, the appellants completed a First Report of Injury (FROI) that identified the date of injury as March 21, 2013, at 5:05 a.m.  The FROI indicated that the first date of lost time was July 2, 2013, and that the employer had been notified of the work injury on July 9, 2013.  The FROI described the injury as resulting from the employee not being able to see clearly after eye surgery and walking into a shelf causing boxes to fall and injuring the employee’s neck and left shoulder.

The employee was terminated from his employment with the employer in mid-August 2013.  The employee sought employment within his restrictions and obtained part-time work as a sandwich-maker at Arby’s in October 2013.

On January 3, 2014, the employee underwent surgery to repair his left shoulder rotator cuff tear.  Dr. Nemanich kept the employee off work for five months following that procedure while physical therapy was performed.  The employee was released to work with restrictions of no lifting his left arm above his shoulder and no work with his left hand above table level.  Upon being released to work, the employee resumed looking for work within his restrictions.

At the request of the employer and insurer, the employee underwent an independent medical examination with Dr. Mark Engasser on February 20, 2014.  The employee told Dr. Engasser that the injury had occurred when boxes fell from a shelf in the freezer and struck the employee on the neck and left shoulder.  The employee denied having any other prior left shoulder injuries or treatment.             Dr. Engasser noted the employee’s medical records showed a cervical discectomy at C5-C6 with fusion in 1999, treatment for neck and right shoulder pain from 2002 through 2004, and a resumption of right shoulder pain in January 2009.  On March 13, 2009, the employee underwent an open rotator cuff repair with acromioplasty on his right shoulder.  A January 12, 2012, visit was referenced indicating that the employee had left shoulder pain as of that date.

Dr. Engasser also noted there was a gap in time between the falling boxes incident in March 2013 and the employee seeking medical care from Dr. Kim on May 30, 2013.  Dr. Engasser further noted there was no mention of the injury in the preoperative evaluation done on March 28, 2013, before the employee’s eye surgery.^[1]  Dr. Engasser concluded the employee’s report of an injury in March 2013 was not credible, and attributed the employee’s left shoulder pain to spontaneous development of the left shoulder condition over time, not from the impact of a box falling on his left shoulder.  Dr. Engasser opined the left shoulder surgery was reasonable and necessary, but maintained that it was related to a chronic underlying condition and was not related to any work activity with the employer.  Dr. Engasser believed that, had the employee suffered a work injury as described, he would have reached maximum medical improvement within one week of the injury.

By letter report dated May 20, 2014, Dr. Nemanich provided an opinion regarding the employee’s left shoulder injury.  Dr. Nemanich noted that “[i]t was difficult to say at the time [of the post-injury examination] if [the employee] had a pre existing rotator cuff tear as the cuff tear that we did find at the time was quite large, but certainly he had no previous symptoms to this and his symptoms were certainly aggravated with that injury.”^[2]  Dr. Nemanich opined that the subsequent left shoulder surgery had gone well, but that the employee was restricted from overhead work and that restriction would probably be permanent.  Dr. Nemanich stated the employee would not be at maximum medical improvement for two to three months, but that his disability rating would be about 6 percent.

The employee filed a claim petition on October 15, 2013, seeking wage loss benefits, permanent partial disability, payment of medical expenses, and rehabilitation services.  Following a hearing, in a Findings and Order issued on August 28, 2014, a compensation judge found the employee sustained a work injury on March 22, 2013, and that the work injury was a substantial contributing cause of the employee’s left shoulder condition after that date.  The compensation judge further found the employee provided timely notice to the employer by at least May 28, 2013, when the employee notified the assistant manager of his March 2013 shoulder injury.  The employer and insurer appeal.

In reviewing cases on appeal, the Workers’ Compensation Court of Appeals must determine whether “the findings of fact and order [are] clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.”^[3]  Substantial evidence supports the findings if, in the context of the entire record, “they are supported by evidence that a reasonable mind might accept as adequate.”^[4]  Where evidence conflicts or more than one inference may reasonably be drawn from the evidence, the findings are to be affirmed.^[5]  Similarly, “[f]actfindings are clearly erroneous only if the reviewing court on the entire evidence is left with a definite and firm conviction that a mistake has been committed.”^[6]  Findings of fact should not be disturbed, even though the reviewing court might disagree with them, “unless they are clearly erroneous in the sense that they are manifestly contrary to the weight of the evidence or not reasonably supported by the evidence as a whole.”^[7]

The employer and insurer argued that the compensation judge’s determinations are erroneous and not supported by substantial evidence in the record.  For the reasons set forth below, we disagree.

To establish a compensable claim under the Workers’ Compensation Act, an employee must show that the employer had actual knowledge or written notice of the occurrence of the employee’s injury.^[8]  Actual knowledge is knowledge of such information as would put a reasonable person on inquiry.  For actual knowledge to exist, an employer must have some information connecting the employee’s work activity with an injury.^[9]  In this case, the compensation judge accepted and found credible the employee’s testimony that the night manager, C.W., was made aware of the employee’s injury on the day it occurred.  In doing so, the compensation judge concluded the employee provided timely statutory notice to the employer in accordance with Minn. Stat. § 176.141.^[10]

At the hearing, the employer and insurer submitted into evidence an “Employee Clocking Summary” listing employees that worked in the store during the week of March 18 through March 24, 2013.^[11]  The employer and insurer maintain that the Clocking Summary “unequivocally controverts” the employee’s testimony that the night manager, C.W., was working on the date of injury and was aware of the injury on the day it occurred.  The employer and insurer explain in their brief that the Clocking Summary is objective data that C.W. did not work on March 21, 2013, but reported for work on the evening of March 22, 2013.  The employer and insurer maintain the Clocking Summary’s objectivity and clarity is determinative of the issue of notice and nothing further, including the employee’s testimony, is necessary.  We are not persuaded by the employer and insurer’s argument.

It is clear from the evidence reviewed that the compensation judge did not ignore the Clocking Summary, but found it “difficult to interpret” and concluded it did not necessarily refute the employee’s testimony.  The employee testified that C.W.’s hours were not always regular and that he came into work most days whether he was scheduled to work or not.  The employee further testified that C.W. was present that day and assisted him after the boxes fell on him in the freezer.  He stated C.W. brought Advil and a bottle of water and told him to sit for about 20 minutes, and that he was directed to finish his shift behind the counter.

The Clocking Summary was one piece of evidence used for the purpose of disputing the employee’s claim that he reported an injury within the requirements of Minn. Stat. § 176.141.  The compensation judge listened to the employee’s direct and cross-examination on this point, considered the Clocking Summary as to this point, and heard the arguments of counsel on this point.  After due consideration, the judge made his determinations as to notice and credibility, and we are not aware of any rule that clocking summaries must always be given precedence over the testimony of a witness.  In this case, we do not agree that it controverted the employee’s testimony.

The assessment of witness credibility is the unique function of the trier of fact, and this court must give due weight to the compensation judge’s opportunity to assess the credibility of witnesses.^[12]  It is not the role of this court to re-evaluate the credibility and probative value of a witness’s testimony and choose inferences different from that of the compensation judge.  Whether this court might have viewed the evidence differently is not the point; the question is whether the findings of the compensation judge are supported by evidence that a reasonable mind might accept as adequate.^[13]  We do not conclude the compensation judge erred in finding the employee a credible witness, and substantial evidence supports the conclusion that the employer, at least implicitly, had actual knowledge of the injury sufficient to put a reasonable person on inquiry as of the date of the injury.

The compensation judge found that the employer had notice of the work injury “at least by May 28” relying on the employee’s report to the assistant manager.  Under Minn. Stat. § 176.141, a claim may be compensable if notice is given within 180 days and the employee shows that failure to give prior notice was due to mistake, inadvertence, or ignorance of fact or law.  In this case, the compensation judge concluded the employee’s post-injury eye surgery and related pain medication masked the employee’s left shoulder symptoms.  Upon his return to work on May 28, 2013, the employee experienced shoulder pain and reported the onset of pain and the work injury to the assistant manager.  The judge held that the employee did not know until that time that his shoulder had been seriously injured, a mistake of fact, and held the employee provided timely statutory notice to the employer by at least May 28, 2013.^[14]

The employer and insurer maintain the compensation judge’s finding regarding a mistake due to pain medication masking the employee’s symptoms is not supported by substantial evidence, and argue that the compensation judge improperly added a nonexistent standard of seriousness to the statute.  We disagree.

The scope of the circumstances under which the notice statute permits an employee to delay notice for up to 180 days is broad, especially in the circumstances of mistake or inadvertence.^[15]  The statute allows an employee wide latitude in showing the reason why notice was not given earlier.^[16]  Included among the reasons for giving notice later is the failure to recognize the seriousness of the injury.^[17]

The employer and insurer argued that the compensation judge did not take into account the gap in time between the employee’s claimed work injury and initiating pain medication for his eye surgery; and if that period had been considered, the compensation judge would have determined the employee suffered no personal injury on March 21, 2013.  The record shows that the employer and insurer advanced this argument before the compensation judge at hearing.  The employee testified as to the pain that he experienced on the date of the injury.  The compensation judge found that the employee did not realize the significance of his shoulder injury until he returned to work.  The compensation judge found credible the employee’s testimony that he began experiencing more pain with the resumption of his job duties on May 28, 2013, particularly reaching over his head to move boxes.

It is well settled that the date on which an employee has sufficient knowledge to trigger the duty to give notice of injury is a question of fact.^[18]  This court must affirm the compensation judge’s findings of fact unless they are “clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.”^[19]  There is adequate evidence in the record as a whole to support the compensation judge’s determination that any delay in reporting the injury to the employer was due to a mistake on the employee’s part regarding the significance of his shoulder injury.  The record is consistent that the employee provided timely notice to the employer by at least May 29, 2013.

The employer and insurer argue they were not required to demonstrate prejudice to effectuate a notice defense.  Minn. Stat. § 176.141 sets out that notice provided within 180 days is not deficient where there has been a mistake by the employee unless the employer shows prejudice by failure to receive earlier notice.  The compensation judge accepted the employee’s testimony that he reported the injury to C.W. on the day it occurred.  There is no issue regarding timeliness of notice provided to the employer through the employee having informed C.W. at the time of the injury.  As discussed above, the compensation judge also found that notice of the injury was given to the assistant manager shortly after the employee returned to work, which was more than 30 days but less than 180 days after the date of injury.

Regarding the alternative notice finding, the employer and insurer assert that there is no requirement to show prejudice to interpose a notice defense to the compensability of an injury.^[20]  We agree.  However, as we stated above, the compensation judge found that “the employee did not know his shoulder had been seriously injured, a mistake of fact, and the employer has presented no argument regarding prejudice resulting from the later notice.”^[21]  We find nothing in the record to contradict the determinations contained in Finding 8 of the compensation judge’s Findings and Order.  Under these circumstances, Minn. Stat. § 176.141 requires a showing of prejudice to the employer and insurer to succeed in a notice defense.

The employer and insurer argue that the compensation judge’s determination that the employee sustained a work injury on March 22, 2013, is clearly erroneous and unsupported by substantial evidence.  The employer and insurer maintain that the employee’s testimony is contradicted by the Clocking Summary and not credible, and urge this court to adopt Dr. Engasser’s opinion over that of Dr. Nemanich.

As discussed above, the compensation judge did not err in accepting the employee’s testimony regarding the occurrence of the work injury as credible over the evidence presented in the Clocking Summary.  Having addressed the arguments regarding the Clocking Summary, the compensation judge’s determination that the employee suffered a work injury on March 22, 2013, is affirmed.

In concluding the employee sustained a work injury on March 22, 2013, the compensation judge found Dr. Nemanich’s opinion to be more persuasive than that of Dr. Engasser.  The employer and insurer assert, however, that Dr. Nemanich’s opinion lacked adequate foundation as he did not discuss what records he reviewed, did not specifically address the employee’s treatment history for the left shoulder, and did not explain how the mechanism of the injury would have caused the employee’s left shoulder condition.

The competency of a witness to provide expert medical testimony depends upon the witness’s scientific knowledge and practical experience with the issue which is the subject of the offered testimony.^[22]  Dr. Nemanich initially examined the employee on July 1, 2013, shortly after the employee returned to work, and has treated the employee’s left shoulder condition since that time.  The doctor’s chart notes were submitted into evidence as well as his report of May 20, 2014.  Dr. Nemanich took a history from the employee, examined and treated the employee on multiple occasions, and reviewed relevant medical records and tests.  This level of knowledge affords adequate foundation for a doctor to render an expert medical opinion.^[23]  Further, an expert medical opinion does not lack foundation because the doctor fails to explain the mechanism of injury or the underlying reasons for the opinion.^[24]

Although the employer and insurer have outlined their objection to the opinions of Dr. Nemanich as one of foundation, their objection is essentially that the compensation judge did not adopt the opinions of Dr. Engasser over the opinions of Dr. Nemanich given the data from the Clocking Summary.

In summary, the compensation judge here was presented with conflicting medical opinions, both with adequate foundation, and found the opinion of Dr. Nemanich more persuasive.  Where there is adequate foundation for the opinion adopted by the judge, this court must normally uphold the compensation judge’s choice between medical experts.^[25]  Substantial evidence supports the compensation judge’s determination that the employee sustained a work injury on March 22, 2013, that the injury was a substantial contributing cause of the employee’s left shoulder condition, and we, accordingly, affirm.