The employee appeals the compensation judge’s findings that the employee’s right ankle and bilateral knee work injuries sustained on September 18, 2013, were temporary in nature; that the employee had been able to work but failed to search for work, thus making her ineligible for temporary total disability benefits; that the employee’s testimony regarding a job search was not credible and she failed to conduct a diligent job search following her layoff from the employer in February 2014 and thereafter she removed herself from the labor market in May 2014 when she enrolled full time at St. Paul College.^[1]  We affirm.

In 1990, the employee began working part time for the Pioneer Press (employer) in its production plant and, thereafter, began full time as a trainee.  As a trainee, the employee inserted advertisements into newspapers, counted stacks of papers, and operated a bundle tying machine.  The bundles were then transferred by conveyor to truck drivers for delivery.  By 2000, the employee became a union journeyman performing similar and additional production type duties.  She worked 35 hours per week.

On September 18, 2013, the employee went outside the employer’s building on her lunch break.  While walking across a gravel median in the employer’s parking lot, the employee stumbled and fell, landing on both hands and both knees.^[2]  The employee sought medical treatment at HealthPartners Urgent Care later that day.  She was diagnosed with bilateral hand and knee pain, a right ankle sprain, a left knee contusion/effusion, and a hand contusion.  She was taken off work and referred for rehabilitation.

On September 24, 2013, the employee was seen at HealthPartners by Sara E. Hartfeldt, M.D.  She complained of bilateral knee pain, worse on the left, pain in both palms and wrists, and right ankle pain.  Her left knee showed no erythema, but had mild to moderate pre-patellar edema.  The range of motion was full in flexion and extension.  Ligamentous and meniscal testing appeared normal.  The employee’s right ankle showed lateral anterior ligamentous tenderness and a slightly limited range of motion due to pain and swelling.  Dr. Hartfeldt diagnosed a right ankle sprain and a left knee sprain.

On September 27, 2013, the employee returned to HealthPartners where she was seen by Emily Bannister, M.D.  Her left knee pain had improved but she continued to have pain in the back of her right foot.  Mild swelling was noted at the left knee and back of the right foot.  Dr. Bannister released the employee to return to sedentary work under restrictions that she avoid weight bearing.  She was given a CAM boot for the right ankle and crutches.

On October 4, 2013, the employee was seen again by Dr. Bannister.  There was full range of motion and 5/5 strength in both ankles and knees.  However, the employee complained of significant pain with ankle inversion and plantar flexion against resistance.  She also reported pain with left knee flexion.  The employee was diagnosed with a left knee sprain and a right Achilles sprain.  Dr. Bannister released the employee to sedentary work with no weight bearing on the legs.

On November 11, 2013, the employee was evaluated by Thomas Nelson, M.D., an orthopedic surgeon, on behalf of the employer and insurer.  She reported her left knee pain was somewhat improved but that her right ankle continued to be very painful.  Dr. Nelson opined that the employee had sustained a right ankle sprain to the right anterior talofibular ligament, and possibly to the anterior inferior tibiofibular ligament and the anterior syndesmosis.  In his opinion, the injury had not yet resolved.  He also opined that the employee sustained a mild contusion to the left knee, which had resolved without evidence of internal derangement.  He opined that the employee was able to work full duty at her pre-injury job without restrictions with the use of her right ankle brace.  He did not think she needed crutches.  In his opinion, she did not need any restrictions related to the left knee.

On December 6, 2013, the employee reported to Dr. Hartfeldt that her overall pain was much improved.  Dr. Hartfeldt referred the employee to a sports medicine specialist, Marifel Fernandez, M.D., to review the progression of the employee’s recovery.

The employee saw Dr. Fernandez on December 10, 2013.  The employee reported her left knee was somewhat better.  However, she now complained of a burning sensation in her right knee after walking.  Examination of the right knee showed no deformities or tenderness and the range of motion was full.  Examination of the right ankle showed soft tissue swelling on the left.  Ankle strength, ligament testing, and range of motion were normal.  The doctor diagnosed a right ankle sprain and right knee sprain.  The employee was released for driving and to return to sedentary work.

On December 31, 2013, Dr. Fernandez recommended that the employee continue with physical therapy and that she participate in a work conditioning program.  She was continued on sedentary work restrictions.

The employee returned to light duty work for the employer in December of 2013.  The work involved doing paperwork while sitting at a desk.  The employee testified that she had no trouble working in her light duty position between December 2013 and February 15, 2014, when the employer’s production plant closed and she was laid off.  In conjunction with her layoff, the employee was offered retraining assistance or help in finding another position under a state displaced worker program.  She decided to return to school to learn Spanish and sign language interpreting, and made arrangements to enroll in such a program with the assistance of the Work Force Center.  She also attended classes at the Work Force Center on how to prepare a resume and how to interview.

On February 28, 2014, the employee was seen again by Dr. Fernandez who noted that the insurer denied payment for the employee’s work hardening program.  The employee reported that her right ankle was better, with only intermittent pain, but that her right knee hurt daily.  Dr. Fernandez advised that the employee continue physical therapy and again recommended a work hardening program.  He also recommended an MRI of the right knee.

The employee underwent an MRI of her right knee on April 25, 2014.  The MRI showed moderate chondromalacia patella, and mild chronic thickening and scarring of the medial collateral ligament, suggestive of a ligament sprain.  There was no evidence of a meniscus tear.

The employee returned to see Dr. Fernandez on April 30, 2014.  The right knee MRI results were discussed; surgery was not indicated.  The employee underwent cortisone injections in both knees.  Dr. Fernandez noted that the employee’s left knee had been hurting for a few months, likely because of changes to her gait pattern.  She recommended that the employee resume physical therapy and eventually participate in a work hardening program.  Weight loss was also suggested.  The employee asked for a letter indicating whether or not she was employable in her current condition, as laid-off employees who could carry 50 pounds were being given an opportunity to apply to work for the Star Tribune.  Dr. Fernandez indicated the employee was unable to work and took her entirely off work until completion of a work hardening program.

On May 12, 2014, the employee was seen for a rehabilitation consultation by Dawn Marie Van House, QRC.  The QRC determined the employee was a qualified employee for rehabilitation services.  She developed a rehabilitation plan with a goal to return the employee to work with a different employer.  The QRC subsequently provided only medical management pending the employee’s release to work by Dr. Fernandez.

The employee began summer school classes in Spanish and American Sign Language at St. Paul College on May 27, 2014.  The classes were paid for by the state dislocated workers program.

The employee began a work hardening program at NovaCare on June 30, 2014.  On that date she demonstrated the ability to lift 30 pounds at waist level and 10 pounds from floor to waist and waist to eye level.  She could carry 20 pounds in each hand and could push/pull 100 pounds.

On July 29, 2014, Dr. Fernandez saw the employee “for bilateral ankle and right knee pain.”  The employee reported that her knees were “getting better.”  Dr. Fernandez reiterated the importance of a weight loss program “to prevent future progression of her knee arthritis.”  She continued to restrict the employee from work until completion of the work hardening program.

The employee completed work hardening on August 29, 2014.  The discharge summary noted that she was now able to lift 55 pounds at waist level, 50 pounds from floor to waist, and 40 pounds from waist to eye level.  She could carry 35 pounds in either hand and could push or pull 150 pounds.  The QRC testified that based upon this testing, the employee would be able to perform medium level work.

Dr. Fernandez evaluated the employee on the same date.  The assessment was bilateral chronic knee pain, chondromalacia patella of the right knee, sequela of a right knee MCL strain, and sequela of a right ankle sprain.  Dr. Fernandez noted that she thought that the condition of the employee's knees was “as good as it is going to get.”  She felt that the employee could tolerate sedentary work.  She issued work restrictions for seated work only and avoidance of weight bearing.

On September 30, 2014, the employee was reexamined for the employer and insurer by Dr. Nelson.  The employee stated that she was no longer having problems with her right ankle.  Her current complaints were of swelling and pain in both knees, with pain greater on the left and swelling greater on the right.  Dr. Nelson diagnosed the employee with a resolved right ankle sprain, chondromalacia patella of the right knee, and mild medial compartment narrowing of the left knee, currently asymptomatic.  He found no evidence that the work injury had caused an injury to the employee’s right knee.  In his opinion, the September 18, 2013, right ankle and left knee injuries had resolved, and the employee had reached maximum medical improvement (MMI) from her work injuries, without permanent disability.  Dr. Nelson opined that the employee was able to work without restrictions.

On September 17, 2014, the employee’s QRC noted in a progress report that the employee had completed her work hardening program and had been released to sedentary work by Dr. Fernandez.  She further noted that the employee was still attending school which was being paid for by the State of Minnesota.  Her recommendations were to follow up with the employee to discuss her educational training and determine an estimated graduation date.

The QRC met with the employee on November 11, 2014.  The employee noted that she was now attending school part time.  The QRC asked if she would like to seek part time work while attending school.  The employee stated that her goal was to return to school full time, but she would think about it.  The employee did not state either that she was or had been looking for employment.  On November 21, 2014, the QRC prepared a Rehabilitation Plan Amendment to extend the plan completion date, recommending that rehabilitation be placed on hold while the employee completed her education, and resume when she was able to participate in placement activities and seek suitable work with a different employer.

Dr. Fernandez issued a narrative report on January 21, 2015, in response to a request for her medical opinion.  Her diagnosis was a right ankle sprain and bilateral knee sprain/contusion, and a right knee chronic medial collateral ligament sprain and chondromalacia patella.  Noting that the right knee MRI from April 25, 2014, showed mild chronic thickening and scarring of the medial collateral ligament, she concluded that the ligament was likely sprained during the fall at work.  Dr. Fernandez opined that the work injury also caused a left knee sprain and contusion and a sprain of the left collateral ligament of the right knee.  She explained that she had removed the employee from work from April 30, 2014, until August 29, 2014, because she was unable to carry 50 pounds at that time, which was required for a position with the Star Tribune.  Dr. Fernandez opined that the employee was capable of sedentary work and should continue a home exercise program.

On April 15, 2015, Dr. Nelson issued a supplemental report based on his review of Dr. Fernandez’s January 2015 narrative report.  Dr. Nelson noted that the report had not changed his prior opinion.  He stated that the employee’s work injury had resulted in a resolved right ankle sprain, but that there was no evidence that she sustained a sprain or contusion to either knee.  He noted that a fall directly on to the front of the knee, as described by the employee, would not cause a sprain to the medial collateral ligament.  He disagreed with Dr. Fernandez’s assessment that the September 18, 2013, incident caused a chronic medial collateral ligament injury.  Dr. Nelson opined that the employee’s medial collateral ligament condition was due solely to age-related degenerative changes in the knee.  Dr. Nelson saw no need for work restrictions.

On April 16, 2014, a hearing was held before a compensation judge at the Office of Administrative Hearings.  The employer and insurer admitted liability for right ankle and left knee injuries.  The parties stipulated that the employee had reached MMI on August 29, 2014.  The issues at the hearing were: whether the employee had also sustained a right knee injury; whether the employee’s injuries were temporary or permanent in nature; whether the employee was required to conduct a diligent job search, and if so, whether she did; whether the employee had removed herself from the labor market; and whether the employee was entitled to temporary total disability benefits from and after the date of her layoff through 90 days past MMI.

The employee testified that, after being laid off, she had looked for work at the Job Force Center and through various websites.  She also asked about possible job openings when she was out shopping.  She testified that she had spent about one to two hours seeking work on weekdays, and that she had applied for approximately two to three hundred jobs as of the date of hearing.  The employee also submitted her job logs into evidence at the hearing.  These showed an almost entirely uniform pattern of a single job search contact on each day, except for weekends and holidays, beginning on February 17, 2014, and running through March 21, 2015.  On cross-examination at the hearing, the employee acknowledged that during a June 26, 2014, deposition, she was asked whether she had “looked for work, at all, since you stopped working at the Pioneer Press” and answered “No.”  She addressed the apparent contradiction between her deposition testimony and the job logs, which showed roughly 91 job search contacts prior to the date of the deposition, by explaining that she had understood the expression “look for work” as applying only to in-person job applications, while the contacts on her job logs preceding the deposition had been made on the internet or by telephone.

Following the hearing, the judge found that the employee had sustained a right ankle injury and bilateral knee injuries on September 18, 2013, but that these injuries were temporary in nature and had resolved no later than September 30, 2014.  The judge adopted the medical opinion of Dr. Nelson that the employee had been able to work, whether or not under restrictions, at all times during the period for which temporary total disability benefits were being sought.  The judge did not find the employee’s job search testimony and documentary evidence credible.  She found that the employee had failed to conduct a diligent job search following her layoff from the employer on February 15, 2014, and that she had subsequently removed herself from the labor market on May 27, 2014, when she began attending classes at St. Paul College.  The employee appeals.

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.”  Minn. Stat. § 176.421, subd. 1.  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.”  Hengemuhle v. Long Prairie Jaycees, 358 N.W.2d 54, 59, 37 W.C.D. 235, 239 (Minn. 1984).  Where evidence conflicts or more than one inference may reasonably be drawn from the evidence, the findings are to be affirmed.  Id. at 60, 37 W.C.D. at 240.  Similarly, 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 evidence or not reasonably supported by the evidence as a whole.”  Northern States Power Co. v. Lyon Food Prods., Inc., 304 Minn. 196, 201, 229 N.W.2d 521, 524 (1975).

Moreover, it is the function of the trier of fact to resolve conflicts in expert medical testimony.  Nord v. City of Cook, 360 N.W.2d 337, 342 W.C.D. 364, 372-73 (Minn. 1985).  This court is required to uphold a compensation judge’s choice between medical expert opinions, unless the expert opinion, as chosen, assumes facts that are not supported by substantial evidence.  Id.

Lastly, assessment of witness' credibility is the unique function of the trier of fact.  Spillman v. Morey Fish Co., 270 N.W.2d 781, 31 W.C.D. 187 (Minn. 1978).

The compensation judge found that the September 18, 2013, work injury resulted in injury to both of employee’s knees and to her right ankle.  She further found that the employee’s injuries were temporary in nature.  In her memorandum, the judge noted that the medical records suggested that the employee’s knee injuries were minor, and that post-injury symptoms in the right knee had apparently resolved by the end of September 2013, while the left knee was also normal as of Dr. Nelson’s examination in November 2013.  The judge accepted the opinion of Dr. Nelson to the effect that the employee’s subsequent right knee pain was unrelated to the work injury.  The judge further noted that the employee reported to Dr. Nelson that by September 30, 2014, she no longer had problems with her right ankle.

On appeal, the employee argues that the compensation judge erred in relying on the opinions of Dr. Nelson.  The employee contends that Dr. Nelson’s opinions were “not plausible,” objecting principally to portions of his opinion dealing with the nature and extent of the employee’s injuries.  The employee notes that Dr. Nelson’s opinion failing to link the employee’s knee conditions to her work injury was both contrary to the employee’s testimony and to the judge’s finding of bilateral knee injuries.  However, the judge notes in her memorandum that while she expressly adopted Dr. Nelson’s opinion in other matters, she disagreed with Dr. Nelson’s  position that the employee did not sustain a right knee injury on September 18, 2013.  The judge found that the employee did sustain a right knee injury.  A judge may rely on part of a medical expert’s opinion and is not obligated to accept either all or none of the expert’s opinions in order to rely on that doctor’s expertise.  See Johnson v. L. S. Black Constr. Co., slip op. (W.C.C.A. Aug. 18, 1994) (citing City of Minnetonka v. Carlson, 298 N.W.2d 763, 767 (Minn. 1980) (a factfinder generally “may accept all or only part of any witness’ testimony”)).

The employee points out that Dr. Nelson saw the employee only twice, and did not provide medical care, suggesting that greater weight should have been given to the views of the employee’s treating physicians.  She also argues that the compensation judge erred in failing to discuss the contrary views of some of the employee’s treating physicians in detail.  Finally, the employee suggests that the judge should not have accepted Dr. Nelson’s opinions without having first made express findings with respect to Dr. Nelson’s competence.  We disagree.  These concerns relate to the persuasiveness or weight accorded to the medical opinions, but they are insufficient to establish a lack of foundation. Drews v. Kohl’s, 55 W.C.D. 33, 38-39 (W.C.C.A. 1996).  While a finder of fact may choose to afford greater weight to the opinion of a treating physician, the finder of fact is not required to do so.  Caven v. Ag-Chem Equip. Co., Inc., slip op. (W.C.C.A. Sept. 14, 1993).

A judge’s choice between expert opinions must be upheld unless the facts assumed by the expert in rendering his opinion are not supported by the evidence.  See Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985).  The facts assumed by Dr. Nelson are not inconsistent with the evidence submitted, therefore, we affirm.

The employee claimed entitlement to temporary total disability benefits from February 15, 2014, when she was laid off from her post-injury light duty work for the employer, through November 29, 2014 (90 days past the stipulated date of MMI).

The compensation judge found that the employee had not performed a reasonably diligent job search.  The judge further found that the employee had withdrawn from the labor market to enroll in a full time course of study, rather than seek employment.  The judge thus concluded that the employee was not entitled to temporary total disability compensation during the claimed period.

The employee disputes the finding of a lack of diligent job search, arguing that she had in fact been applying for jobs and that the compensation judge erred in disregarding her testimony and job logs.  The finding was based on the judge’s conclusion that the employee’s testimony lacked credibility.  Assessment of a witness’s credibility is the unique function of the trier of fact.  Spillman v. Morey Fish Co., 270 N.W.2d 781, 31 W.C.D. 187 (Minn. 1978).  The judge explained in her memorandum that she did not find the employee’s testimony and job logs credible in that the job logs, showing extensive job search activities prior to the date of the employee’s deposition, were contradicted by her deposition testimony where she specifically denied having searched for work.

The employee asserts that her deposition testimony does not impugn her credibility because she was not asked at the deposition why she was not looking for work.  The employee implies that, had she been asked, she would have said that she had been completely taken off work by Dr. Fernandez.   This argument, however, fails to explain why her job logs listed job contacts for periods in which her deposition testimony specifically denied she had searched for work, and clearly contradicts her hearing testimony that she did, in fact, look for work.  As an alternative explanation for her deposition testimony, the employee also testified in the hearing below that she did not define “applying for jobs” as including job seeking activities other than in-person job applications.  The compensation judge, however, was not required to accept this explanation.  The weight and interpretation given to the employee’s deposition testimony vis-a-vis hearing testimony and job logs offered as evidence are matters is within the judge’s discretion.

Whether an injured employee makes a reasonably diligent search for suitable employment is a question of fact which must be upheld unless manifestly contrary to the evidence.  McClish v. Pan-O-Gold Baking Co., 336 N.W.2d 538, 36 W.C.D. 133 (Minn. 1983).  In light of the credibility findings of the compensation judge, we conclude that the judge’s findings as to the absence of a reasonably diligent job search have substantial support in the record, and we affirm.

The employee, however, argues that, in any event, she was not required to perform a job search, having been completely taken off work by Dr. Fernandez.  Dr. Fernandez took her off work from April 30, 2014 until August 29, 2014, when she completed the work hardening program.  Initially, we note that this span of time does not include the full period for which temporary total compensation was claimed, and would not provide a basis for reversing the denial of temporary total disability compensation between February 15, 2014, and April 30, 2014.  More importantly, however, the compensation judge did not accept Dr. Fernandez’s opinion that the employee was totally disabled from work during this period.  In her memorandum, the judge notes that she adopted Dr. Nelson’s opinion that the employee was capable of working under restrictions throughout the period for which temporary total disability benefits were sought.  As we have discussed above, the judge’s reliance on Dr. Nelson’s expert medical opinion was within her discretion and does not constitute reversible error.

The employee began her studies at the St. Paul College on May 27, 2014, and, as of the date of hearing, continued to be enrolled in a full time course of study there.  Neither the employee nor her QRC had ever sought or obtained authorization of this course of study as a workers’ compensation retraining program.  The compensation judge found that the employee had removed herself from the labor market when she began taking a full time course of college study.  In Le v. State, University of Minnesota, 330 N.W.2d 453, 35 W.C.D. 665 (Minn. 1983), the supreme court held that temporary disability benefits are not payable to an injured employee during a period of retraining absent certification or approval for retraining or a demonstrated inability to find other employment.^[3]

The employee argues that the Le case is distinguishable because she was disabled from work for most of the period in which she was taking classes.  This argument relies on her prior argument that the judge should have accepted the off work restrictions of Dr. Fernandez.  As we have already affirmed the compensation judge’s determination that the employee was able to work during this period, we find this argument unpersuasive as well.

Having affirmed the findings that the employee failed to perform a reasonably diligent job search from and after February 15, 2014 and that she withdrew from the labor market on May 27, 2014, we affirm the compensation judge’s denial of temporary total disability compensation for the claimed period.

The appendix to the employee’s brief included documents that were not admitted into evidence at the hearing below, including the text of the employee’s deposition.  We have not considered any material not in evidence in reaching our decision in this case.