The employer and insurer appeal from the compensation judge’s award of permanent total disability benefits and from his denial of equitable apportionment.  We affirm.

The employee was born in 1949 and served in the United States Marine Corps after graduating from high school.  Upon leaving the military, the employee worked in a variety of jobs, in various states, before returning to live in Minnesota.  At some point he received forestry training, and he took some classes at a technical school and at the University of Minnesota-Duluth, but he did not earn a college degree.^[1]  He also worked in the building trades, eventually starting his own business as a general contractor.

Medical records indicate that the employee has a history of low back pain dating back to at least 1980.  Sometime in 1998, he apparently sustained a work-related injury to his low back while self-employed as a contractor,^[2] and, apparently as a result of this injury, he underwent laser-assisted discectomies at L4-5 and L5-S1, performed on September 29, 1998, by Dr. Richard Freeman.  Three days after surgery he returned to his usual job, without restrictions.  However, the employee testified that, around the date of his surgery he “sort of promoted” himself from performing carpentry and other construction labor to a more supervisory position.  According to treatment records, the employee had occasional flare-ups of low back pain after his 1998 surgery, but his recovery was considered to be good, and physicians did not limit him with respect to work, hobbies, or activities of daily living.  The employee was apparently uninsured for workers’ compensation purposes at the time of the 1998 injury.

In January of 2001, the employee commenced employment as an iron worker for Mid Central Steel Erectors [the employer], working full time with a base pay rate of $25.50 an hour.  On March 19, 2001, he sustained a work-related injury while lifting a 200-pound steel beam with a coworker.  The employee testified that, as he lifted the beam, he felt a “snap” or “pop” or “crunch” in his lower back, and, when the pain progressed to the point that he could hardly walk, he left work early and drove himself to a nearby hospital.  He was subsequently sent to physical therapy for “acute low back strain/sciatica,” but his symptoms did not improve, and he was not able to return to his job. Not long after the injury, the insurer assigned QRC Dana Butler to work as the employee’s disability case manager.

On April 18, 2001, the employee underwent an MRI scan, which revealed moderately severe bilateral L4-5 foraminal narrowing, disc bulging at L4-5 and L5-S1, and moderately severe lower lumbar facet degenerative changes.

The employee received continued conservative treatment for low back and leg pain, including steroid injections, medications, more physical therapy, and work hardening.  His symptoms apparently improved somewhat, for a time, and, by the fall of 2001, he was involved in job placement activities coordinated by Ms. Butler.  He did not, however, receive any job offers.

By January of 2002, the employee was again complaining of “excruciating” low back pain.  An electrodiagnostic study to determine the source of lower extremity pain revealed a possible mild chronic polyneuropathy, apparently unrelated to the employee’s low back condition, but the examiner noted that the polyneuropathic changes might be masking a mild radiculopathy.

In early February of 2002, the employee underwent a discogram, which was positive for concordant pain at L5-S1.  A few weeks later, on February 26, 2002, he underwent decompressive laminectomy, discectomy, nerve root foraminotomy, and fusion surgery, with instrumentation from L4 to S1 and placement of a bone growth stimulator.  The employee testified that his symptoms improved following the surgery, and treatment notes from July of 2002 indicate that the employee was at that time experiencing no leg pain and only occasional back pain.

Job placement activities were reinstituted in about February of 2003, a year after the employee’s surgery.  By that time, the employee had been released to sedentary work, 20 hours a week, by Dr. Jed Downs, who had become the employee’s primary treating physician with regard to his low back condition.  Rehabilitation records indicate that the employee made “excellent” job contacts.  He did not, however, obtain employment.

In March of 2003, the employee wrote to Dr. Downs, complaining of severe pain with constant sciatica, as well as burning pain, numbness, and cramping in his feet and toes.  He also indicated that his back and leg pain increased “[a]fter a day of job search,” that he had collapsed three times after the “back of his knees” went numb, and that he was experiencing waves of depression, diminished energy level, and apprehension.  The employee’s purpose in writing was to ask Dr. Downs to change his pain medication and to prescribe something to help him sleep.  By then, Dr. Downs had already prescribed methadone, a narcotic, for the employee’s back pain.  Subsequent medical records characterize the prescription as “chronic methadone maintenance.”

By the spring of 2003, the employee had begun considering the possibility of returning to school.  In August of 2003, the insurer asked Ms. Butler to suspend job placement activities, and Ms. Butler wrote that, given the employee’s 20-hour per week restriction on working, it would be fruitless to either continue a job search or have the employee retrained, because he had been such a “high wage earner” on the date of injury.  However, after additional discussion, reference to vocational testing, and investigation, Ms. Butler drafted a retraining plan, calling for the employee to complete a two-year program in graphic design at Duluth Business University.  The employer and insurer initially objected to the plan but then agreed, and the employee began course work in April of 2004.  In the meantime, in late 2003, the employee was evaluated and treated for thyroid disease and cardiac abnormalities.  Also, on December 16, 2003, he underwent a right total knee replacement procedure.

The employee did relatively well in his retraining classes during the spring and summer quarters of 2004.  Medical records during this period indicate, however, that the employee was complaining of a variety of symptoms, including extreme fatigue, panic attacks, a sensation of falling backwards, dizziness, tingling hands, increasing low back pain, bloating, and trouble breathing.  Also during this period, he was reevaluated and received additional treatment for ongoing thyroid and cardiac problems, including, apparently, what was his second myocardial infarction.

The employee began the fall quarter at Duluth Business University, having enrolled in three computer classes.  However, in about October of 2004, he withdrew from school.  The employee testified that he quit the graphic design program for a combination of reasons, including increasing back pain, fatigue, problems with concentration, and numbness and pain in his feet.  He also testified that the 30 minute drive to and from school was hard on his back.

In a November 2, 2004, treatment note, Dr. Downs indicated that it had been “just too tough for [the employee] to continue with courses, given ongoing pain problems and difficulties with depression,” and the doctor concluded that the employee was “permanently and totally disabled, from a combination of his chronic, non-malignant pain, status post fusion and biomechanical restrictions, congestive heart failure status post two MI’s, and depressive episodes.”

In March of 2005, Ms. Butler closed her file because Dr. Downs had permanently restricted the employee from work.  As Ms. Butler understood it, Dr. Downs’ restriction was based on the employee’s low back condition.  Diagnostic scans indicate that the employee’s fusion did not become solid and that the hardware has loosened.

In January of 2006, the employee underwent surgery on his right thumb, a trapezial resection arthroplasty and tendon transfer.  He may also need surgery on his left thumb, and there is some possibility that he may undergo revision surgery for the failed fusion.  He has not worked since his March 19, 2001, work injury and has not looked for work since leaving school in the fall of 2004.

The matter came on for hearing before a compensation judge on June 2, 2006, for resolution of the employee’s claim for permanent total disability benefits.  The employer and insurer alleged that the employee was not permanently and totally disabled; that, in any event, the 2001 work injury was not a substantial contributing cause of his permanent total disability, if any; and that liability for benefits, if any, should be equitably apportioned.

At the beginning of the hearing, a long discussion was held about the admissibility and/or relevance of evidence concerning the employee’s psychological condition.  Apparently, at a pretrial conference, the compensation judge had granted the employer and insurer’s request to exclude consideration of the employee’s psychological condition when deciding the issue of permanent total disability, because the employer and insurer had not had a reasonable opportunity to obtain an expert opinion on the issue.  After additional argument at hearing, the compensation judge reiterated his ruling, indicating that he would not “take into account any of the psychological [evidence].”  While the compensation judge accepted all of the employee’s medical records into evidence, including extensive records concerning the employee’s psychiatric symptoms and treatment, he later agreed to the employer and insurer’s request to “redact” the psychological records.

Four witnesses testified at hearing: Ms. Butler; the employee; Carol Anderson, the employer and insurer’s independent vocational expert; and Jacquelyn Koski, the employee’s former girlfriend and housemate.  Other evidence included the employee’s voluminous treatment records; rehabilitation records; a report from Scott Campbell, the employee’s independent vocational expert; several reports from Dr. William Fleeson, the employee’s independent medical examiner; and deposition testimony and reports from Dr. William Akins, the employer and insurer’s independent medical examiner.

In a decision issued on August 17, 2006, the compensation judge concluded that the employee had been permanently and totally disabled since March 19, 2001, the date of his work injury, and that the March 19, 2001, work injury was a substantial contributing cause of that permanent total disability.  The judge also denied the employer and insurer’s request for apportionment.  The employer and insurer appeal.

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 (2006).  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 the 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).

An employee is totally disabled if his “physical condition, in combination with his age, training, and experience, and the type of work available in his community, causes him to be unable to secure anything more than sporadic employment resulting in an insubstantial income.”^[3]  Schulte v. C.H. Peterson Constr. Co., 278 Minn. 79, 83, 153 N.W.2d 130, 133-34, 24 W.C.D. 290, 295 (1967).  Total disability is considered permanent if it is likely to last indefinitely.  See Behrens v. City of Fairmont, 533 N.W.2d 854, 856, 53 W.C.D. 41, 43 (Minn. 1995).  The work injury need not be the sole cause of disability, only a substantial contributing cause.  See, e.g., Salmon v. Wheelbrator Frye, 409 N.W.2d 495, 40 W.C.D. 117 (Minn. 1987).

In the present case, it is undisputed that the employee’s fusion surgery was unsuccessful and that the employee is subject to significant limitations related to his low back condition.  As the employer and insurer’s own independent examiner, Dr. Akins, explained, virtually “everything” in the fusion procedure failed, and he conceded that the employee’s back is painful.  Dr. Akins further testified, however, that the employee is capable of either continuing his retraining or working, in a sedentary job, despite his low back condition and, presumably, despite his other medical problems.^[4]  The employer and insurer’s independent vocational examiner, Carol Anderson, testified that, if the employee completes the graphic design retraining program, or perhaps completes course work online at a local community college, he “should” be employable in the local labor market.  There is, however, extensive evidence to the contrary.

As previously indicated, Dr. Downs, the primary treating physician with respect to the employee’s back, indicated that the employee is permanently and totally disabled, and it is reasonably inferable from his records that Dr. Downs was basing his opinion in large part on the employee’s low back condition.  In fact, Dr. Downs’ opinion, standing alone, might well be sufficient to establish both that the employee is permanently totally disabled and that the March 19, 2001, injury is a substantial contributing cause of that disability.  In addition, Dr. Fleeson, the employee’s independent medical examiner, concluded that the employee is not physically capable of sitting in school for more than an hour or so and that he is not able to perform significant sustained gainful employment.  When asked what he meant by “significant sustained gainful employment,” Dr. Fleeson replied,^[5]

On appeal, the employer and insurer do not contend that the employee’s experts lack foundation for their opinions as to permanent total disability.  Rather, the employer and insurer contend that there is no objective evidence that the employee’s low back condition has worsened, so as to preclude him from completing retraining, that the employee’s condition might well improve with further treatment, making a permanent total disability determination premature, and that the employee’s nonwork-related medical conditions constitute superseding, intervening causes of his disability.  These arguments have no merit.

There may be no objective evidence that the employee’s low back condition has worsened, from an orthopedic standpoint, since Dr. Downs first released the employee to participate in retraining.  However, the employee testified that his symptoms did in fact worsen over time, and his testimony to this effect was corroborated by Ms. Butler.  Again, that there is an objective basis for the employee’s severe pain complaints cannot seriously be disputed.  Furthermore, while other medical conditions might well have contributed to the employee’s decision to leave school when he did, it was clearly reasonable for the compensation judge to conclude that the employee’s back condition substantially influenced that decision.

We also reject the employer and insurer’s contention that a permanent total disability determination is premature.  It is true that Dr. Akins and Dr. Fleeson have suggested that the employee undergo additional back surgery, in an effort to obtain a solid fusion.  However, Dr. Akins, the employer and insurer’s expert, acknowledged that “[r]evision surgeries don’t have a high level of success,” and that, “statistically, people who have histories of depression, histories of chemical dependency,^[6] history of long chronic back pain do not improve very much with spinal surgeries of this nature.”  The employer and insurer’s contention that the employee may improve with additional psychological treatment is both surprising and improper.  Having successfully persuaded the compensation judge to disregard the employee’s psychological condition in considering the question of permanent total disability, the employer and insurer may not now argue that the possibility of psychological improvement renders a permanent total disability determination premature.^[7]

Finally, while we acknowledge that the employee suffers from a number of potentially serious nonwork-related medical conditions,^[8] we find no basis in the record to conclude that these conditions constitute superseding, intervening causes of the employee’s permanent total disability.  The employer and insurer have offered no expert opinion to support their contention in this regard, and it is apparent that the employee’s experts based their permanent total disability opinions in substantial part on the pain and limitations resulting from the employee’s failed fusion.

On the date of the hearing, the employee was nearly 57 years old and had not worked in more than five years.  Ms. Butler testified that the employee fully cooperated with rehabilitation efforts, and this is undisputed on appeal.  The employer and insurer concede that the employee’s failed fusion necessitates severe limitations on his activities, and two medical and two vocational experts have indicated that the employee is permanently precluded from working.  Because the record as a whole overwhelmingly supports the conclusion that the employee is permanently and totally disabled as a substantial result of his March 19, 2001, work injury, we affirm the compensation judge’s decision on this issue.

Dr. Akins indicated that the employee’s low back condition and resulting disability were substantially attributable to both the employee’s 1998 work injury, which apparently occurred when the employee was self-employed and uninsured, and to the 2001 work injury, and the doctor apportioned liability 40% to the 1998 injury and 60% to the 2001 injury.  In his deposition, he explained that the 1998 laser discectomy surgery had predisposed the employee to further problems by increasing instability at the involved lumbar levels.  Dr. Fleeson responded to Dr. Akins’ apportionment opinion as follows:

On appeal, the employer and insurer contend, in part, that the compensation judge erred in accepting Dr. Fleeson’s opinion, in that Dr. Fleeson erroneously believed that the employee’s 1998 surgery involved only one lumbar level, when in fact both L4-5 and L5-S1 were operated on.  The employer and insurer also note that fusion surgery had been considered during the employee’s treatment in 1998 and that the employee had not really done “fine” following the laser surgery but instead had had several flareups. We concede that the employer and insurer’s factual argument has some merit; however, we are nevertheless persuaded that the judge’s denial of apportionment was appropriate.

In general, employers take employees as they find them and are liable for an employee’s entire disability when a work injury aggravates or accelerates a preexisting condition.  See, e.g., Fleener v. CBM Indus., 564 N.W.2d 215, 56 W.C.D. 495 (Minn. 1997).  “Except in rare circumstances, see, e.g., Pearson v. Foot Transfer Co., 301 Minn. 489, 221 N.W.2d 710, 27 W.C.D. 535 (1974), the doctrine [of equitable apportionment] has no application to injuries that are not compensable under the Minnesota Workers’ Compensation Act.”  Sorby v. Soil Testing Servs. of Minn., No. WC06-118, slip op. at 6 (W.C.C.A. Aug. 2, 2006).  As such, equitable apportionment is not available for an out-of-state work injury, see id., where the employee has settled claims for a previous work injury, see Johnson v. Tech Group, Inc., 491 N.W.2d 287, 47 W.C.D. 367 (Minn. 1992), where liability for an earlier work injury has ended by operation of law, see, e.g., Marsolek v. Miller Waste Mills, 244 Minn. 55, 69 N.W.2d 617, 18 W.C.D. 244 (1955), or where claims for a previous work injury are barred by the statute of limitations, Warnecke v. Hoerner Waldorf Champion, 33 W.C.D. 654 (W.C.C.A. 1991).  Finding no compelling reason to deviate from the underlying principle of these cases, we conclude that equitable apportionment may not be used to reduce an employer and insurer’s liability in cases where a portion of the employee’s disability is attributable to an earlier injury sustained while the employee was self-employed and uninsured.  Rather, the earlier injury is no different from a preexisting nonwork-related injury, disease, or condition for which apportionment is not allowed.  See Marsolek, 244 Minn. 55, 69 N.W.2d 617, 18 W.C.D. 244.  The judge’s denial of equitable apportionment is therefore affirmed.^[9]