The employer and insurer appeal the compensation judge’s finding that the employee is permanently and totally disabled.  We affirm.

On March 2, 1998, Timothy P. O’Neil, the employee, sustained an admitted injury to his lumbar spine while working as a fabricator for J Craft, Inc., the employer, which was insured for workers’ compensation liability by AP Capital.  The employer and insurer initially paid temporary total disability benefits, and later paid temporary partial disability benefits through April 8, 1998, while the employee worked reduced hours.  In July of that year, the employee sustained an exacerbation of his low back while working at his regular position.  A few weeks later, he returned to light-duty work with the employer.  In November 1998, since there was no additional light duty work available, the employer offered the employee a janitorial job for four hours per day.  The employee did not accept the position, claiming that he was not physically able to perform the job.  A hearing was held on March 2, 1999.  The compensation judge found that the part-time janitorial job was outside of the employee’s restrictions and denied the discontinuance of benefits.^[1]  Neither party appealed this decision.

In April 1999, the employee’s physician, Dr. Thomas Balfanz, gave the employee restrictions of four hour days, no lifting over 25 pounds occasionally and 10 pounds frequently, avoid repetitive bending below knee level, occasional twisting, and to alternate positions between sitting and standing for five minutes out of every thirty minutes.  A month later, the employee was evaluated by an independent medical examiner, Dr. Paul Yellin.  Dr. Yellin agreed with Dr. Balfanz’s restrictions but indicated the employee could increase his hours beginning with four hours per day and increasing up to eight hours.

In July 1999, the employee received a written job offer from the employer for a full-time forklift operator.  The employee did not accept the job since he was only released for part-time work.  Four months later, Dr. Balfanz revised the employee’s restrictions to four hours per day, increasing to eight hours per day, no lifting over 25 pounds occasionally and 10 pounds frequently, to avoid excessive vibrational forces and repetitive bending below knee level, occasional twisting, stooping, squatting, and reaching, and to alternate positions between sitting and standing for five minutes out of every thirty minutes.  A month later, the employer offered the employee a part-time forklift operator position, which would increase to full-time work, or in the alternative, a chip and grind operator position.  The employee did not accept either of the positions based on his belief that they were beyond his restrictions.  In support of this position, Dr. Balfanz opined that the employee could not perform the functions of either job.

Based on the refusal of the job offers, the employer and insurer filed a petition to discontinue benefits.  A hearing was held on December 15, 1999, and the record was held open until January 7, 2000.  The compensation judge found that the jobs offered to the employee were outside of his restrictions, and denied the petition to discontinue benefits.^[2]  Neither party appealed this decision.

The employee’s medical care and treatment continued.  Dr. Balfanz referred the employee to Dr. Matthew Monsein at Sister Kenny Institute.  Dr. Monsein evaluated the employee’s back symptoms and indicated that the employee had chronic pain syndrome and signs of clinical depression.  He recommended that the employee participate in the pain rehabilitation program.  The employee completed the program in May 2000, and Dr. Monsein indicated the employee could return to light or sedentary work with restrictions including changing positions frequently, no crawling or squatting, and no lifting over 20 pounds.  In June of 2000, the employee returned to Dr. Balfanz, who indicated to the employee that he could work eight hours a day with significant restrictions: occasional lifting up to 20 pounds, occasional bending, stooping, twisting, pushing, pulling, and reaching over shoulder level, and no bending below knee level, squatting, crawling, climbing over two feet high, or situations requiring good balance.  Later that month, the employer offered the employee a janitorial position.  Dr. Balfanz reviewed the offer and opined that the employee could not perform the position.  The parties subsequently agreed that the employee would not be able to return to work with the employer.

The employee began working with his QRC to find a job with a different employer.  He found a position with Custom Precision in August 2000, and temporary partial disability benefits commenced.  The employee stopped working at Custom Precision in October 2000 because he was working more than full time and he could no longer physically tolerate the work.  No further rehabilitation services were provided to the employee.  His rehabilitation file was subsequently closed and the employee did not conduct a job search after October 2000.  During this time, the employee applied for Social Security disability benefits and was approved.

The employee continued to treat with Dr. Balfanz for his back condition and reported signs of depression.  In March 2001, Dr. Balfanz referred the employee to a psychiatrist and to a rheumatologist for evaluation of possible fibromyalgia.  In November 2001, Dr. Haramandeep Makkar diagnosed the employee with a major depressive disorder and a chronic pain disorder.  He prescribed Neurontin and referred the employee to a psychologist for therapy.  In December 2001, the employee was evaluated by psychologist Dr. Greg Pelletier for pain management and psychotherapy.  Dr. Pelletier diagnosed the employee with a pain disorder and chronic pain.  Dr. Makkar referred the employee to a neurologist and transferred the employee’s psychological care to Dr. Dean Watkins.  Dr. Watkins began treating the employee in January 2002 after diagnosing the employee with a depressive disorder secondary to his general medical condition and a pain disorder associated with back pain/back surgery.

Also in January 2002, Dr. Balfanz referred the employee for a neurological consultation with Dr. Jhablall Balmakund, who concluded that the employee was not a surgical candidate.  The employee was also evaluated by Dr. David Hanson a month later.  Dr. Hanson diagnosed “fibromyalgia, which is probably associated with chronic low back pain, sleep disturbance, and depression,” and chronic low back pain.^[3]  The employee underwent a neurological evaluation by Dr. Thomas Falloon on March 4, 2002.  Based on a comparison of a February 13, 2002, MRI^[4] and a 1998 MRI, Dr. Falloon stated that he would not proceed with surgery unless the symptoms were intractable or the employee did not respond to conservative measures.

The employee returned to Dr. Watkins in March 2002 for continued medication management.  Dr. Watkins indicated that the employee’s depressive symptoms were related to his pain and limited function.  The employee was evaluated on July 1, 2002, by Dr. Thomas Gratzer at the employer and insurer’s request.  Dr. Gratzer reviewed the employee’s medical records, took a history, did a psychiatric evaluation, and conducted psychological testing.  Dr. Gratzer opined that the employee had a personality disorder which began before his injury, an adjustment disorder with mixed anxiety and depressed mood, and somatoform disorder, which were not disabling.

In July 2002, the employee began a pain program with Dr. Todd Hess at United Pain Center.  Dr. Hess prescribed methadone, which the employee tried but he stopped taking the medication since it limited his ability to function.^[5]  When he returned to the pain center in August 2002, the employee tested positive for marijuana use.  In September 2002, the employee reported to Dr. Watkins that he was experiencing back pain, breathing problems, arm pain, and increasing depressive symptoms.  The employee also reported that he had been using marijuana for pain control for seven months.  Dr. Watkins prescribed Effexor and recommended that the employee stop using marijuana.  In November 2002, Dr. Hess told the employee he would not prescribe methadone for the employee until he underwent a chemical dependency evaluation.  The employee was concerned about becoming addicted to a narcotic medication and indicated that the marijuana use was more helpful to him.  The employee did not return to the pain center.

The employee continued to treat for his physical and psychological conditions.  In September 2002, Dr. Balfanz modified the employee’s restrictions to allow him to work eight hours per day with the ability to change positions as needed, occasional lifting up to ten pounds, and occasional climbing, balancing, stooping, crouching, kneeling, and crawling.  At a follow-up appointment with Dr. Watkins in December 2002, the employee reported significant improvement with his depressive symptoms.  The employee continued to do well psychologically through June 2003.  At that time, Dr. Balfanz opined that the employee’s medical and psychological conditions were caused by his 1998 back injury and that his work restrictions were related to his back condition, not to his fibromyalgia condition.  By September 2003, the employee reported increased depressive symptoms and Dr. Watkins listed the employee’s diagnoses as depressive disorder secondary to general medical condition, panic disorder, and pain disorder.  The employee reported that he had stopped using marijuana at that time.

In June 2005, the employee was re-evaluated by Dr. Falloon for surgical options.^[6]  The employee reported back pain with bilateral leg pain, numbness and weakness, difficulty walking, and that he was using a cane.  Dr. Falloon stated that a multilevel fusion surgery was possible for intractable symptoms.  The employee did not proceed with surgery.  The following month, the employee underwent a psychiatric consultation at the St. Cloud VA Clinic, and the employee began treating there for his psychiatric and medical conditions.  He continued to be diagnosed with and treated for major depressive disorder through 2010.  The employee returned to Dr. Falloon on June 14, 2010, with the same symptoms he had in 2005.  Dr. Falloon suggested decompressive lumbar laminectomy for moderate spinal stenosis.  The employee again elected not to undergo surgery.

In February 2011, the employee underwent a three-day vocational/psychological evaluation by Phillip Haber, M.S., Psy. D., a licensed psychologist.  The evaluation required psychological testing, vocational testing, and work sample testing.  At the end of the evaluation, Dr. Haber concluded that the employee was permanently and totally disabled.

On April 6, 2011, at the employer and insurer’s request, the employee was again evaluated by Dr. Gratzer.  Based on new knowledge of the employee’s marijuana use, Dr. Gratzer revised his previous diagnosis of adjustment disorder to substance-induced anxiety mood disorder and cannabis dependence.  He opined that the employee’s anxiety and depressive symptoms could not be fully evaluated while he was using marijuana, and that acute marijuana intoxication would affect psychometric testing, but that the extent of intoxication at the time of Dr. Haber’s testing would be difficult to determine.  He noted that Dr. Haber did not document any manifestations of intoxication during testing, but was of the opinion that Dr. Haber overly relied on the employee’s pain behaviors.  Dr. Gratzer re-stated his opinion that the employee did not have a disabling psychiatric condition, either related or unrelated to the employee’s work injury.

In June 2011, at the employer and insurer’s request, Michael Kahnke, a certified disability case manager, conducted a vocational assessment of the employee.  He was of the opinion that the employee was capable of gainful employment and that if the employee had conducted a job search, it was highly likely he could have found employment since 2000.

On July 25, 2011, the employee filed a claim petition for permanent total disability benefits from and after October 10, 2000, based on his back injury, secondary major depressive disorder, and consequential pain disorder.  The employer and insurer denied the claim.  A hearing was held on December 15, 2011.  At the hearing, the employee testified that he continued to use marijuana to help him function physically, but not on a daily basis. He also testified that he did not use it before being tested by Dr. Haber.  The compensation judge awarded the employee permanent and total disability benefits.  The employer and insurer 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.^[7]  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.^[8]  Fact findings are clearly erroneous if the reviewing court, looking at the entire evidence, is left with a definite and firm conviction that a mistake has been committed.^[9]  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.”^[10]

The compensation judge, in reliance on the employee’s treating physicians and the opinion of licensed psychologist, Dr. Haber, found that the employee required physical restrictions due to his work-related injuries.  The employer and insurer contend Dr. Haber’s opinion is not an expert opinion because first, it does not meet the scientific theory or technique generally accepted in the relevant scientific community; and second, Dr. Haber’s opinion has no reliable foundation to meet the competency standard for an expert witness.  Therefore, the employer and insurer argue, the judge erred in accepting Dr. Haber’s opinions regarding the physical restrictions and the finding that the employee is permanently totally disabled must be reversed.  We are not persuaded.

First, the employer and insurer argue that Dr. Haber’s testimony should be excluded since it does not meet the standard for scientific evidence under the Frye-Mack standard in Minnesota courts.^[11]  Minnesota courts have adhered to the Frye-Mack standard for determining the admissibility of expert testimony based on scientific techniques and principles.^[12]  The Frye-Mack standard requires the scientific theory or technique to be generally accepted in the relevant scientific community and to have reliable foundation.^[13]  We do not believe that the Frye-Mack test is the appropriate analytical framework for evaluating the admissibility of the expert vocational testimony of Dr. Haber.^[14]  In addition, the Minnesota Supreme Court recently held in Doe 76C v. Archdiocese of St. Paul and Minneapolis^[15] that the standard for foundational reliability under Frye-Mack is “nearly identical” to the standard under the evidentiary rules.^[16]  As discussed below, the compensation judge clearly considered the foundational reliability of Dr. Haber’s opinion in accepting that opinion.  Evidentiary rulings in workers’ compensation hearings are generally within the discretion of the compensation judge,^[17] and we conclude that the compensation judge did not err by failing to apply the Frye-Mack standard in this case.

Second, the employer and insurer argue that since Dr. Haber is not a medical doctor, he does not qualify as an expert medical witness by knowledge, skill, training or education to testify in the form of an opinion on the subject of the employee’s physical restrictions.  The employer and insurer maintain that Dr. Haber’s testimony should have been excluded since his testimony on physical restrictions was medical testimony, not vocational testimony.  The employer and insurer also contend that Dr. Haber did not rely on Dr. Balfanz’s restrictions and for that reason could not render a reliable opinion of the employee’s ability to work based on his own observations.  We are not persuaded.

Providing an expert vocational opinion on the employee’s sustained work capability is not giving medical testimony on restrictions, but is simply stating a vocational opinion on the employee’s physical capabilities to perform given physical activities.  Dr. Haber conducted a three-day vocational evaluation of the employee using a combination of work activities, work samples, psychometrics, behavioral observations, and other techniques to assess the employee’s vocational strengths, vocational weaknesses, functional limitations and any other barriers to employment.^[18]  Based on the combined results of this testing, Dr. Haber concluded that the employee was permanently and totally disabled.  Dr. Haber’s conclusion was premised on the employee’s medical conditions and his physical capabilities as to his abilities and limitations for the requirements of a job, including the specific job at Custom Precision.  Dr. Haber detailed his observations in his report, and the compensation judge specifically found that the testing reflected the employee’s capabilities and was consistent with the employee’s experience working at Custom Precision.  The compensation judge specifically found the employee to be a credible witness^[19] and that the Custom Precision job was not within Dr. Balfanz’s restrictions.  The compensation judge could reasonably rely on the employee’s testimony, the medical evidence of the employee’s restrictions, and Dr. Haber’s observations during testing to determine that the employee is significantly limited in his vocational abilities.  We therefore affirm these findings by the compensation judge.

The employer and insurer also argue in their brief that the compensation judge erred by failing to consider that the employee’s chronic use of marijuana skewed the psychometric testing to such a degree that the testing was unreliable to determine whether the psychological condition was work related and whether the injury precluded the employee from gainful employment.  The employer and insurer maintain that Dr. Haber’s opinions to the contrary do not have adequate foundation since he is a rehabilitation psychologist, not a medical doctor.  The employer and insurer rely on Dr. Gratzer’s opinion that the employee’s anxiety and depressive symptoms could not be fully evaluated in light of his marijuana use and that psychometric testing could be affected by acute marijuana intoxication.

We note that Dr. Gratzer did not opine that chronic marijuana use could “skew” the results of the employee’s testing, but that the testing “could be affected by acute marijuana intoxication.”^[20]  Further, the compensation judge had additional testimony and evidence in the record on this issue.  The compensation judge specifically accepted as credible the employee’s testimony that he was not using marijuana while he was being tested by Dr. Haber.  Dr. Haber testified that he saw no evidence of impairment from the use of marijuana during testing and that the use of marijuana does not render the testing results invalid.^[21]  Dr. Haber’s testimony that he did not see any evidence of impairment during the testing is not expert medical testimony, but is his personal opinion based on his observations of the employee during three days of testing.  Dr. Gratzer also opined that there was no way to determine the extent of any intoxication at the time of Dr. Haber’s testing and noted that Dr. Haber had not documented any manifestations of intoxication during the testing.  The employer and insurers’ argument is based in large part on the same objections to the credibility and foundation of the witnesses’ testimony, and we have accepted the compensation judge’s conclusion on credibility of the witnesses who testified at hearing and on the foundation for Dr. Haber’s observations.  The compensation judge did not err by considering Dr. Haber’s opinion on this matter.

As a final point on this issue, the employer and insurer wonder if the employee would have been able to complete the pain center program and possibly have returned to work if he had discontinued using marijuana.  This argument is based on speculation and we have already accepted the compensation judge’s conclusions on the weight given the expert opinions of the doctors.  Based on the record as a whole, the judge’s impression was that the employee’s use of marijuana and the failure to complete the pain program had little effect on his disability or his ability to find and hold employment.  The medical records and expert medical opinions of Dr. Balfanz, along with the treatment records of Dr. Monsein and Dr. Hess, support the judge’s conclusion that the employee’s withdrawal from marijuana and completion of Dr. Hess’ pain program would not improve the employee’s overall condition enough to make him employable, and we affirm.

The employer and insurer next argue that the judge erred by finding that the employee’s medical and psychological conditions prevent him from obtaining gainful employment.  The compensation judge noted the employee suffered a significant physical injury which left him severely disabled with pain.  He had undergone multiple treatment modalities and pain programs but treatment proved difficult and provided no measurable improvement.  Over time, the employee went on to develop chronic pain and eventually depression.  Dr. Haber opined that the employee was permanently and totally disabled based on his observations and the testing results.  The employer and insurer again argue that Dr. Faber’s opinion lacks foundation.

Foundation goes to the competency of a witness to provide an expert opinion.  The competency of an expert depends both on the witness’s scientific knowledge and the witness’s practical experience with the subject matter of the offered testimony.^[22]  Sufficient knowledge of the subject matter may be obtained by personal knowledge and experience, review of medical records, a hypothetical question or testimony at the hearing.^[23]  Here, Dr. Haber had personal knowledge of the employee and practical experience.  He conducted an evaluation, including psychometric testing, and work sample testing in order to determine the employee’s ability to work.  His level of knowledge and experience is sufficient to provide adequate foundation on permanent total disability for an expert opinion.  Dr. Haber provided an expert vocational opinion of the employee’s abilities and limitations as they relate to meaningful gainful employment.  His testimony at the hearing was an assessment of whether the employee’s physical capabilities were sufficient to hold a job.  The compensation judge could reasonably rely upon Dr. Haber’s expert opinion on permanent total disability.^[24]

We also note the judge relied on other evidence, including the medical history and records of Dr. Balfanz, who opined in June 2003 that the employee’s medical and psychological conditions were caused by his 1998 back injury.  The judge found Dr. Balfanz’s opinions persuasive and did not accept Dr. Gratzer’s opinion on the lack of causation between the work injury and the employee’s psychological condition.  Where there is adequate foundation for the opinion adopted by the judge, this court must uphold the compensation judge’s choice among experts.^[25]  The compensation judge analyzed the criteria to measure the competency of multiple experts^[26] in forming her conclusions and we review the record under the standard of substantial evidence.  Given the exhibits and oral testimony presented in this case, substantial evidence supports the judge’s findings, and we affirm.

The employer and insurer also claim that substantial evidence does not support the compensation judge’s determinations that the employee could not perform the job at Custom Precision and that he could not have found alternative employment had he made a job search.  They argue that the employee was released to work full time when he worked at Custom Precision and that he could have returned to Dr. Balfanz for additional restrictions if needed, and that his Custom Precision employer could have accommodated the employee’s need to work fewer hours.  The employee testified that he was working at Custom Precision more than full time, partly to make up for a co-worker who did not always show up for work.  He was in a lot of pain and was very depressed at the time he quit working for Custom Precision.

Based on the employee’s description of his work with Custom Precision, the compensation judge found that this position was not within the employee’s restrictions, since he was working more than 40 hours per week and had to stand in a static position for more than half an hour while working.  Given Dr. Balfanz’s and Dr. Monsein’s restrictions for the employee in 2000, substantial evidence supports the compensation judge’s finding that the employee could not perform this job within his restrictions and that it was speculative that the job could have been further modified.

The compensation judge also accepted Dr. Haber’s opinion that a job search would have been fruitless based on the employee’s inability to engage in sustained employment activity.  The employer and insurer argue that the job market was good in 2000 and that he could have found alternative employment.  Michael Kahnke, a certified disability case manager, conducted a vocational assessment of the employee and opined that the employee was capable of gainful employment and that the employee could have found employment since 2000.  However, he had no specific employment openings from that time and only samplings of openings from 2005.  As stated by this court in Walsh v. K-Mart Corp., a job search is not a prerequisite to a finding of total disability where the evidence reasonably establishes that a job search would be futile.^[27]  Given the entire record on appeal, substantial evidence supports the compensation judge’s determinations that the employee could not perform the job at Custom Precision and that he could not have found alternative employment had he made a job search, and we affirm.

An employee is permanently totally disabled if the employee’s medical condition in combination with age, training and experience, and the work available in the labor market, cause the employee to be incapable of finding anything other than sporadic employment at an insubstantial wage.^[28]  The question of permanent total disability is dependent primarily upon the employee’s vocational potential, not the employee’s physical condition per se.^[29]  As such, the lack of a medical opinion as to permanent total disability is not dispositive.  Based on both vocational and medical evidence, the compensation judge made findings of fact that coincide with the Schulte^[30] factors to determine that the employee was permanently totally disabled, and we affirm.