Chesley Truck Sales (hereinafter Chesley) and its insurer, MADA (with claims administered by Berkley Risk Administrators), appeal from the compensation judge’s decision to apportion 30 percent of the liability for benefits paid by I-State Truck Center (hereinafter I-State) and its insurer, Liberty Mutual Insurance Company, to Chesley and its insurer and ordering Chesley and its insurer to reimburse 30 percent of the benefits paid by I-State and its insurer to the employee.  We affirm.

The employee, Dennis Younker, began working as a truck mechanic for Chesley Truck Sales in approximately 1995.  As a truck mechanic, he overhauled engines, clutches, brakes, and electrical systems.  He worked full time, and his job involved lifting items such as drums and clutches weighing between 75 and 200 pounds.  He estimated that he lifted these types of weights during about 10 to 15 percent of his work day.

On March 6, 1999, the employee was working on a truck cab that was tilted forward.  The employee had to work underneath the cab to attempt to “wrestle a radiator out.”  Within a couple weeks, the employee noticed pain in his back and into his legs.

The employee saw Dr. Edward Hames on December 30, 1999.  Dr. Hames recommended an EMG and myelogram.  Doctor Hames diagnosed “refractory left L5 radiculopathy” and noted a large left L4-5 lateral disc herniation.  The employee underwent an L4-5 lumbar microdiscectomy on February 16, 2000.  A medical record shortly after the surgery indicated that “a large free fragment was encountered, extruding from the L4-5 disc laterally compressing the exiting left L4 nerve root.”

The employee returned to work on light duty, initially, and he was released to return to work without restrictions on April 16, 2000.  The employee testified that he did return to work with Chesley, doing all of the tasks that he had before his injury in 1999.  However, he said that he had to modify the way that he did his job.  The employee said he would often have to stop to walk around and stretch his back out.  He testified that it varied when he would have to take the breaks, but it was “sometimes 30 minutes and sometimes I could go for up to an hour.”  At times, the employee would get assistance when lifting, but this was because there were certain things that were too heavy for just one person to lift.

The employee was eventually assessed with an 11 percent permanent partial disability rating as a result of the 1999 injury.  He testified that he “always had pain in the lower back at least 75 percent of the time” between the time that he returned to work in April 2000 and his second injury in 2006.  The employee said he would use over-the-counter medication, heat pads, and stretching learned in physical therapy to help relieve the pain.  The employee did not return to the doctor between 2000 and 2006 because he believed “I would come [sic] more disabled or unable to do my work, that I would have had to find a different job.”

Chesley was eventually bought out by I-State.  The employee testified that his job remained the same after the buyout and change in ownership.

On August 18, 2006, while he was working for I-State, the employee sustained another injury to his low back as he was replacing a transmission.  The employee testified that he had pain in both of his legs.  The pain in his left leg was worse than the pain in his right, but he indicated that his symptoms would change from one leg to the other.  The employee underwent chiropractic treatment initially, and he later began treating with Dr. Garry Banks.  The employee eventually underwent surgery with Dr. Mark Larkins on March 5, 2010, for L4-5 stenosis, stable L4-5 spondylolisthesis, and L5 radiculopathy.  An additional surgery was performed on August 5, 2011, in the nature of a decompression and repair of a dural leak.

The employee also had significant complications after the surgeries in 2010 and 2011 in the nature of staph infections that required continuing care and treatment for infected surgical wounds.  The employee testified that he had three surgeries relating to his infections, along with other medical care and treatment related to the infections.  At the time of the hearing in this matter, which took place on April 24, 2013, the employee’s infections had not completely healed.  In addition, the employee had not yet been released to work.

The employee, I-State, and its insurer, Liberty Mutual, entered into a stipulation for settlement in 2010, and the Office of Administrative Hearings issued an Award on Stipulation on July 14, 2010.  The stipulation noted the March 1999 injury date and stated,

Doctor Tilok Ghose evaluated the employee at the request of Chesley and its insurer, and he issued a report dated February 22, 2012.  He opined that “the March 6, 1999 injury is not a substantial contributing factor to any or all of the claims for medical and disability after August 18, 2006.”  Doctor Ghose indicated that the employee’s March 6, 1999, injury resulted in low back complaints that caused the employee left lower extremity symptoms.  He noted that the employee was able to return to work without restrictions following his surgery in 2000, and there was no ongoing medical care or treatment between 2000 and 2006.  Doctor Ghose then stated that the employee sustained a new injury on August 18, 2006, involving the low back and the opposite leg, the right leg.  Therefore, Dr. Ghose opined that the August 2006 injury was the substantial contributing factor for any and all claims for medical and disability after August 18, 2006.  Doctor Ghose also opined that “Mr. Younker’s disability is 50 percent the result of the August 18, 2006 injury and 50 percent the result of his psoriatic arthritis.”

Doctor Paul Wicklund evaluated the employee at the request of I-State and its insurer and issued a report dated March 23, 2012.  Doctor Wicklund opined that the employee’s low back problems began with the injury on March 6, 1999, leaving him with a permanent disability to his low back.  Even though the employee had some relief of low back and leg pain, his L4-5 disc was never normal after the surgical procedure in 2000, and the initial 1999 injury was a substantial contributing cause to further development of back problems.  Doctor Wicklund did not believe the 1999 injury had resolved before the August 2006 injury date.  Doctor Wicklund felt that the employee had a new injury in August 2006 “superimposed on his original injury.”  Doctor Wicklund indicated that he would apportion liability for the employee’s treatment after 2006 equally between both the 1999 and 2006 injuries.  Doctor Wicklund issued a follow-up report dated March 25, 2013.  In that report, he indicated he was diagnosing the employee with status post L4 to the sacrum fusion “times two,” with postoperative wound infection, still healing, and status post L4-5 laminectomy and disc excision, with good result.

The case came for hearing before Compensation Judge Jane Gordon Ertl on April 24, 2013, and she was asked to determine whether the employee’s claims, as settled, were causally related to the injury of March 6, 1999.  She was also asked to determine whether I-State and its insurer were entitled to contribution and/or reimbursement from Chesley and its insurer for workers’ compensation benefits that I-State and its insurer had paid after the August 18, 2006 injury, and, “if so, is contribution or reimbursement payable to the low back claim, the infection claim, or both?”

The compensation judge determined that the 1999 and 2006 injuries were both substantial contributing factors in the employee’s disability and need for medical treatment (including treatment for the post-surgical infection) after August 2006, and, as a result, that the claims settled by the stipulation for settlement were causally related to both the 1999 and 2006 injuries.  The compensation judge further determined that liability for the benefits paid by I-State and its insurer were apportioned as follows:  “30% to the injury of March 6, 1999, and 70% to the injury of August 18, 2006.”  Therefore, she ordered Chesley and its insurer to reimburse I-State and its insurer for 30 percent of the benefits paid.

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.”  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, “[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.”  Northern States Power Co. v. Lyon Foods Prods., Inc., 304 Minn. 196, 201, 229 N.W.2d 521, 524 (1975).  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.”  Id.

On appeal, Chesley and its insurer argue that the compensation judge erroneously apportioned 30 percent of the liability for the workers’ compensation benefits, which I-State and its insurer paid after the August 2006 injury, to the employee’s March 1999 injury.

The party seeking apportionment has the burden of proof in relation to its apportionment claim.  See McAlister v. McNeilus Truck Mfg., slip op. (W.C.C.A. Jan 9, 1991).  The Minnesota Supreme Court has held that “the apportionment decision of the [compensation judge] ‘will not be disturbed unless it is manifestly contrary to the evidence or unless consideration of the evidence and inferences permissible therefrom would clearly require reasonable minds to adopt a contrary conclusion.’”  Goetz v. Bulk Commodity Carriers, 303  Minn. 197, 200, 226 N.W.2d 888, 891, 27 W.C.D. 797, 800 (1975) (quoting Peterson v. Dairy Distribs., Inc., 269 Minn. 10, 18, 129 N.W.2d 908, 913, 23 W.C.D. 264, 276 (1964)).  “When considering an apportionment issue, the compensation judge must determine the legal and factual questions as to whether apportionment of responsibility is appropriate; with the appropriateness of apportionment depending on whether adequate evidence of record lays a proper foundation for apportioning the medical and rehabilitation expenses.”  McAlister, slip op. (citing Ringena v. Ramsey County Action Programs, 40 W.C.D. 880, 883 (W.C.C.A. 1988)).

The issue of apportionment is a fact determination made by the compensation judge, and the compensation judge is not bound by medical opinions with regard to apportionment.  See Goetz, 303 Minn. at 200, 226 N.W.2d at 891, 27 W.C.D. at 800.

Chesley and its insurer argue that it was error to apportion any liability for the employee’s low back problems after the 2006 injury to the 1999 injury.  In particular, they argue that Dr. Wicklund failed to consider the nature and extent of the employee’s 1999 injury as compared with his 2006 injury.  They argue that unlike Dr. Ghose, who noted the differing nature between the two injuries, Dr. Wicklund simply asserted that the 1999 injury should be equally apportioned with the 2006 injury because the employee’s current disability involves his low back.  Chesley and its insurer also argue that “the employee’s 2000 surgery completely corrected any symptoms caused by his March 6, 1999 injury,” that the employee was able to perform all aspects of his jobs as a mechanic between 2000 and 2006, and that he did not undergo any medical treatment during that time.

This court will generally affirm the factual determinations of a compensation judge that are based on the choice between expert opinions, “so long as the accepted opinion has adequate foundation.”  Smith v. Quebecor Printing, Inc., 63 W.C.D. 566, 573 (W.C.C.A. 2003), summarily aff’d (Minn. Aug. 15, 2003) (citing Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985)).  Dr. Wicklund obtained a history from the employee, reviewed his medical records, and conducted a physical examination of the employee.  This level of knowledge is sufficient to afford foundation for the opinions of a medical expert.  See, e.g., Caizzo v. McDonald’s, 65 W.C.D. 378, 382 (W.C.C.A. 2005).

Because there was adequate foundation for Dr. Wicklund’s opinions, it was within the judge’s discretion to rely on Dr. Wicklund’s expert opinions in reaching her apportionment decision here.  Furthermore, the compensation judge did address the purported deficiencies in Dr. Wicklund’s opinion that Chesley and its insurer raised.  As the compensation judge explained in her memorandum, there were references in some of the medical records, including 2008 chiropractic records, 2009 physical therapy records, 2009 treatment records with Dr. Goertz, and a January 14, 2010, report from PA-C Nathan Champine, indicating that the employee did report symptoms in both legs at various points after the 2006 injury.  The compensation judge also credited Dr. Wicklund’s opinion that the employee’s L4-5 disc “was never normal” after the initial surgical procedure in 2000.  The compensation judge noted that although the employee did have a good result following the 2000 surgery, he had sustained a significant injury resulting in the need for the surgery and a permanent partial disability rating.  Furthermore, the compensation judge stated that although she was apportioning some liability to the 1999 injury, she reduced the amount apportioned by Dr. Wicklund from 50 percent to 30 percent, based on the compensation judge’s conclusion that the 2006 injury was “responsible for a greater portion” of the benefits given the circumstances discussed above.

Chesley and its insurer also argue that the other evidence in the record does not support the compensation judge’s determination.  For example, they argue that the employee told multiple doctors, including Dr. Banks, and even Dr. Wicklund, that his 2000 surgery was successful and that he had a great result from that surgery.  They also argue that in the stipulation in 2010, the employee’s own claims and contentions indicated that his claims at that time were solely related to the August 6, 2006, injury and that the stipulation indicated that the employee had “a complete resolution of his low back and left leg symptoms” following the 2000 surgery.  Ultimately, these arguments amount to a challenge to the compensation judge’s determination that the employee testified credibly regarding his ongoing symptoms.

The compensation judge was aware of the fact that the employee had continued to work between 2000 and 2006.  However, she chose to credit the employee’s testimony that he continued to have ongoing back problems.^[1]  The compensation judge also reviewed and addressed the stipulation.  She noted that the employee had not seen the medical opinion apportioning liability between the injuries until recently, and she did not feel that the language of the stipulation was sufficient to discredit the employee’s testimony about his ongoing symptoms.^[2]

The compensation judge was in the best position to determine the credibility of the employee’s testimony regarding ongoing problems following the 2000 surgery.  On review, we conclude that it was within the judge’s discretion to credit the employee’s sworn testimony over the other evidence presented here.         It is not the role of this court to evaluate the credibility and probative value of witness testimony and choose different inferences from the evidence than the compensation judge.  See Krotzer v. Browning-Ferris/Woodlake Sanitation Serv., 459 .W.2d 509, 512-13, 43 W.C.D. 254, 260-61 (Minn. 1990); Redgate v. Sroga’s Standard Serv., 421 N.W.2d 729, 734, 40 W.C.D. 948, 957 (Minn. 1988).  The record in this case, including the employee’s testimony and Dr. Wicklund’s opinions, provides substantial evidentiary support for the compensation judge’s apportionment decision relating to the employee’s low back injuries.  Therefore, we affirm.

Chesley and its insurer argue that compensation judge’s decision to apportion 30 percent of the treatment related to the infection issues to the 1999 injury is not supported by substantial evidence.

As an initial matter, Chesley and its insurer argue on appeal, as they did at hearing, that Dr. Wicklund is not an infectious disease doctor and, as such, that he was not qualified to causally relate the infection to the 1999 injury.              Arguments regarding an expert’s qualifications go to the weight of the evidence and not the foundation for the expert’s opinions.  See Ruether v. State, Mankato State Univ., 455 N.W.2d 475, 477, 42 W.C.D. 1118, 1121 (Minn. 1990) (stating that questions regarding the qualifications of an expert do not usually go to the admissibility of the expert’s opinion but merely to its weight).  Furthermore, a medical expert is not disqualified from expressing an opinion as to causation simply because he may be testifying outside his area of expertise; rather, the expert’s qualifications and the evidence supporting his opinion go to the weight to be given his opinion.  Id. at 477-78, 42 W.C.D. at 1121-22.  It is then within the compensation judge’s discretion to assess the weight and sufficiency of a medical expert’s opinion.  See id.

The compensation judge disagreed and based her decision, in part, on Dr. icklund’s opinion that because the 1999 injury was a substantial contributing factor in the 2010 and 2011 surgeries, it was also a substantial contributing factor in the infections that later developed at the surgical sites.  Dr. Wicklund is an orthopedic surgeon.  The employee’s infections developed at the site of the surgical wounds after the 2010 and 2011 surgeries.  As such, it was reasonable for the compensation judge to determine that Dr. Wicklund is qualified to give a causation opinion with regard to the infections that developed at the surgical sites.

Chesley and its insurer further argue that the only causal connection between the 1999 injury and the infections following the 2010 and 2011 surgeries is chronological in nature.  In other words, they argue that it was improper to relate the 1999 injury to the infections simply because the infections occurred at some time after the 1999 injury and the recent surgeries.  They also argue that the employee showed no sign of infection, whatsoever, until after the 2010 and 2011 surgeries.  Therefore, they argue that there was no casual connection between the employee’s 1999 injury and his infection issues after 2010 and 2011 surgeries.

In making their arguments, Chesley and its insurer rely heavily on the case of Rindahl v. Brighton Wood Farms, 382 N.W.2d 855, 38 W.C.D. 473 (Minn. 1986).  Rindahl, unlike the case before us, involved a consequential mental health injury claim, and there was no specific medical opinion relating the depression to the physical injury.  The only medical opinion presented in Rindahl stated that “the employee’s emotional problems were attributable to difficulties with interpersonal relations, her problems with employer, family and romantic relationships, and not her physical injuries.”  Id. at 856, 38 W.C.D. at 475.  The compensation judge nonetheless found a causal link between the physical injury and the mental health issues, reasoning that “the anxiety, pain and disability resulting from her work-related injury are logically a substantial cause of the depression.”  Id. (emphasis added).  The Supreme Court reversed, stating that “We do not think causation in this complex and subtle area of emotional distress is entirely a matter of logic, for it does not necessarily follow that because the depression came after the injury that the injury caused the depression.”  Id.  Ultimately, although the employee attributed her depression to her injuries, the court held that something more was needed, and the court held that “some medical opinion causally relating the depression to employee’s physical injuries is required before the depression can be found compensable under the workers’ compensation system.”  Id. at 856-57, 38 W.C.D. at 476.

In the case before us, the compensation judge was not making the same type of “logical” or “chronological” determination that was reversed in Rindahl.  Rather, Dr. Wicklund’s opinions provided substantial evidentiary support for the compensation judge’s determination that the infection issues were a consequence of the 2010 and 2011 surgeries.  We have affirmed the compensation judge’s determination that the 1999 and 2006 injuries were both substantial contributing factors in the need for the 2010 and 2011 surgery.  Therefore, we affirm her apportionment decision relating to the infections and their treatment as a consequence of the 2010 and 2011 surgeries.^[3]