JULIO ESCOBEDO, Employee/Appellant, v. ARCHETYPE SIGNMAKERS and RISK ADMIN. SERVS., Employer-Insurer/Respondents, and NURSE ANESTHESIA SERVS., THERAPY PARTNERS OSI PT, TWIN CITIES ORTHOPEDICS, LAKEVIEW HOSP., HEALTHPARTNERS, HEALTHEAST ST. JOHN’S HOSP. AND OAKDALE CLINIC, and TWIN CITIES ANESTHESIA ASSOC., Intervenors.

The employee appeals from the compensation judge’s determination that the employee’s 2015 work injury was not a substantial contributing cause of his need for right knee replacement surgery and to certain alleged periods of disability. We affirm.

Prior to 2015, the employee had a non-work right knee condition which started as a result of an injury while playing youth football. He subsequently had multiple episodes of right knee pain and locking over several years. The employee underwent a partial lateral meniscectomy of the right knee in 1985, while in high school, for a complex posterior lateral meniscal tear and a ragged longitudinal tear through the posterior horn of the meniscus. The employee testified that after this surgery he was not under knee restrictions and was able to participate in high school and college athletics, and that he had no further right knee treatment until after the 2015 work injury.

On July 8, 2015, the employee sustained an admitted work injury to his right knee while working for the employer as a sign painter. The injury occurred when the employee twisted his knee while he and several co-workers were maneuvering a large sign frame out of a painting booth. The employee first sought medical attention for his right knee injury on July 27, 2015, with Dr. Nicholas Holmes, where he described continued discomfort in the knee since twisting it at work on July 8. In an addendum to his treatment note, Dr. Holmes also noted that the employee reported having had intermittent knee pain in the past, with episodes normally responding to light moderation of activity and icing. The employee was concerned over the present episode as he had not had relief with the same pattern. Mild swelling without bruising was noted and there was mild crepitus with passive motion. X-rays showed lateral joint space collapse with osteophyte formation in the patellofemoral compartment. Dr. Holmes diagnosed osteoarthritis of the right knee and provided a cortisone injection. No work restrictions were imposed.

Over the next several months the employee continued to perform his normal work activities. He testified that he continued to experience pain and swelling in his right knee that caused him to miss work several times. However, the employee did not again see a doctor for his right knee until January 4, 2016, when he returned to Dr. Holmes. At that time, he told the doctor that he had gotten several weeks of pain relief following the injection to his knee in July, but that his knee pain had later returned and had persisted. Dr. Holmes provided another injection and referred the employee for a surgical consultation. The diagnosis was significant primary osteoarthritis of the right knee.

The employee had a surgical consultation with Dr. Kevin Lindgren on January 8, 2016. Dr. Lindgren recommended continued conservative treatment but opined that the employee would eventually require a knee replacement “based on the severity now of his arthritis.” He imposed work restrictions through February 26, 2016, requiring that the employee rest his knee for 5-10 minutes each hour.

On January 20, 2016, the employee returned to Dr. Lindgren and reported that his knee had worsened. His knee was now catching and locking up on a daily basis, causing it to swell and become more painful. Dr. Lindgren suspected either a chondral flap or meniscus tear and recommended an MRI. He imposed stricter restrictions extending through March 2, 2016, including limitations on lifting, climbing, standing and walking, and advised the use of a brace.

The MRI was performed on March 4, 2016. It showed significant changes throughout the knee, including areas of complete bone loss and grade 4 chondromalacia in all three compartments. There was evidence of a partial PCL tear and some tearing of the menisci laterally and medially “with what is left of his meniscus after his previous meniscectomies.”

Dr. Lindgren offered the opinion that the employee’s work injury had resulted in an exacerbation of a chronic condition. He felt that the employee needed to undergo a knee replacement as his best surgical option.

The employee underwent a right total knee replacement on April 6, 2016. Following recovery from the surgery, the employee was released to return to work without restrictions in June 2016. He testified, however, that he subsequently modified the way in which he did his job so as to limit bending the knee, kneeling, and climbing ladders.

The employee filed a claim petition on June 2, 2016, seeking various wage loss benefits as well as the medical expenses associated with his total knee replacement. The employer and insurer denied liability for the claimed benefits, asserting that the work injury was a temporary sprain which had resolved by July 27, 2015, and that it was not a substantial contributing factor in the employee’s disability and need for treatment after that date.

The employee was seen for an IME by Dr. William T. Simonet on November 1, 2016, at the request of the employer and insurer. Dr. Simonet diagnosed degenerative arthritis of the right knee. He concluded that the employee’s injuries prior to his 1985 surgery had resulted in a probable unrecognized ACL tear. He thought that the employee’s meniscectomy had predisposed him to degenerative arthritis of his knee due to ligament instability as well as due to the loss of the meniscus. Noting that the mechanism of injury described by the employee for the July 8, 2015, work injury did not involve falling or striking the knee, Dr. Simonet opined that the employee’s claimed work injury did not aggravate his pre-existing degenerative arthritis. He considered the employee’s meniscal tears part of that pre-existing arthritic process. In his view, all of the changes shown in the July 27, 2015, x-ray had occurred over a long period of time consistent with a long-standing process dating back to the employee’s non-work injury in the 1980s. In Dr.Simonet’s opinion, the need for a total knee replacement was unrelated to the alleged work injury and was due solely to the progression of the employee’s pre-existing condition.

On March 3, 2017, the employee returned to Dr. Lindgren and reported that he had done well since the surgery but was still having some swelling and pain around the knee late in the day. The swelling would go down after resting the knee. Dr. Lindgren recommended stretching exercises.

The employee’s claims for medical expenses related to the knee replacement surgery, and for certain periods of temporary disability, were heard by a compensation judge on March 1, 2017. Following the hearing, the compensation judge found that the employee’s work injury was not a substantial contributing cause of his need for right knee replacement surgery and to the alleged periods of disability. 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(3). Substantial evidence supports the findings if, in the context of the entire record, “they are supported by evidence that a reasonable mind might accept as adequate.” 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).

A decision which rests upon the application of a statute or rule to essentially undisputed facts generally involves a question of law which the Workers’ Compensation Court of Appeals may consider de novo. Krovchuk v. Koch Oil Refinery, 48 W.C.D. 607, 608 (W.C.C.A. 1993), summarily aff’d (Minn. June 3, 1993).

In her memorandum, the compensation judge explained the basis for her conclusion that the employee had failed to prove that the work injury was a substantial contributing cause of the need for surgery or the associated periods of disability. Specifically, the judge noted that there was documentation by Dr. Holmes indicating that the employee had continued to have intermittent knee pain and symptoms following the 1985 surgery; that the nature of the work injury was minor; that no acute findings were present on the MRI scan taken following the work injury; that the x-ray imaging revealed degenerative findings including osteophyte foundation; that Dr. Lindgren’s opinion was slightly equivocal as to causation; and that she accepted the opinion of Dr. Simonet.

The employee points to the long-established principle in Minnesota workers’ compensation law that when the employee’s work activities aggravate, accelerate or combine with a pre-existing condition to produce disability, the resulting disability is compensable. Citing McClellan v. Up North Plastics, slip op. (W.C.C.A. Oct. 18, 1994), the employee points to six factors which this court suggested may be helpful in assessing an alleged workplace aggravation of an underlying condition. These factors include:

Id. The employee argues that this case should have been determined in his favor based on his application of those factors to the evidence. The employee contends that the judge’s reasoning as stated in her memorandum is not consistent with the employee’s proposed McClellan analysis and contains various legal errors.

We note, first, that the compensation judge was not required to specifically consider the McClellan factors in reaching her findings. See, e.g., Calbillo v. MG Waldrum, No. WC05-235 (W.C.C.A. Jan. 31, 2006). Second, and more importantly, the employee’s analysis based on those factors is predicated on giving a different weight to various aspects of the evidence than the compensation judge gave that evidence. For example, in discussing the first McClellan factor, that of the nature and severity of the pre-existing condition, the employee argues that the compensation judge erred by considering the chart note of Dr. Holmes, stating that the employee reported having had intermittent right knee pain and symptoms prior to the work injury. The employee asserts that the compensation judge should not have given any weight to this evidence, because the chart note was written following the work injury and was not contemporaneous with the reported prior right knee symptoms. Similarly, with respect to factor three, the nature and severity of the aggravating injury, the employee argues that the compensation judge erred in giving any weight to the absence of acute findings on the post-injury MRI scan. The other arguments the employee makes in asserting that the compensation judge’s findings are inconsistent with a McClellan analysis similarly primarily rely weighing the evidence differently than did the compensation judge.

As we noted in a similar context^[1] in Wold v. Olinger Trucking, slip op. (W.C.C.A. Aug. 29, 1994), which factors are significant in a particular case and the weight to be given to each factor is generally a question of fact for the compensation judge.

The opinion of Dr. Simonet also supports the judge’s conclusion. A judge’s choice between expert opinions is usually upheld unless the facts assumed by that expert are not supported by the record. Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985). The employee, however, argues that the opinions of Dr. Simonet were “fundamentally flawed to such an extent that they cannot be considered to have any evidentiary weight.” First, the employee argues that Dr. Simonet’s opinion lacked a detailed explanation, and therefore should be deemed to have inadequate foundation. The employee also argues that in the absence of any record of treatment during the interval between the 1985 surgery and the 2015 work injury, the doctor’s opinion that there was a natural progression in the employee’s underlying condition lacked foundation in the record. The employee further objects to the doctor’s failure to provide medical article citations to support his opinion. Finally, the employee contends that there were acute findings on the MRI, but that Dr. Simonet failed to mention them, and that some of the assumptions apparently underlying Dr. Simonet’s opinion were contradicted by the employee’s testimony regarding his symptoms following the work injury.

Dr. Simonet opined that the employee’s injuries prior to his 1985 surgery had resulted in a probable unrecognized ACL tear and that the 1985 meniscectomy had predisposed him to degenerative arthritis of his knee. He also based his opinion that the July 8, 2015, work injury did not aggravate his pre-existing degenerative arthritis on the mechanism of the work injury. In his view, all the changes shown on the July 27, 2015, x-ray were most consistent with a long-standing process dating back to the employee’s non-work injury in the 1980s. We conclude that Dr. Simonet sufficiently explained the facts on which he relied in rendering his opinions and that the underlying factual assumptions he made were consistent with the compensation judge’s findings and the record. Dr. Simonet reviewed the employee’s pre-injury medical history, reviewed the majority of the employee’s post-injury medical records, and examined and took a medical history from the employee. This provided a sufficient foundation for his opinion. See, e.g., Gianotti v. Indep. Sch. Dist. 152, 889 N.W.2d 796, 77 W.C.D. 117 (Minn. 2017). Therefore, we affirm the Findings and Order of the compensation judge.