The self-insured employer appeals from the compensation judge’s award of payment for claimed medical expenses related to the employee’s left knee injury.  We affirm.

This matter involves a dispute over the compensability of medical treatment to the employee’s left knee following his injury on April 2, 2007.  At issue are three Synvisc injections the employee underwent to his left knee in March and April 2008; the parties disagree on whether the injections treated the effects of the employee’s work injury or, instead, treated an underlying condition unrelated to the injury.

The employee, William G. Goenner, has worked for most of his career as an equipment operator.  In approximately August of 2006, he began working for Oscar J. Boldt Construction Company [the employer], where he has primarily operated a crane and forklift.  On April 2, 2007, while stepping up onto a forklift to attach rigging, his left knee twisted, and he felt a very sharp pain in his left knee.  Due to the pain, the employee was unable to walk, so his coworkers pulled him off the forklift, sat him in a wheelchair and drove him to the Hudson Hospital for treatment.

At the hospital, the employee reported that he was unable to bear weight on his left knee.  Dr. Robert Stoy, the examining physician, diagnosed pain in the joint space both laterally and posteriorly.  Although the employee’s plain x-rays appeared to be normal, Dr. Stoy recommended an MRI scan because the employee’s condition was suggestive of a torn meniscus, and also recommended an orthopedic consultation.  That MRI, performed on that same day, was interpreted to show a cleavage tear of the posterior horn of the medial meniscus involving the inferior articular surface.  The MRI also showed degeneration extending through the mid-body of the meniscus, as well as an intra-articular loose body.  Dr. Stoy provided the employee with a knee immobilizer along with crutches, prescribed pain medication, restricted him from work, and recommended an orthopedic evaluation.

The employee consulted Dr. Cyril Kruse, III, on April 5, at Orthopedic Partners, P.A., reporting severe left knee pain with pain radiating down his leg, as well as difficulty bending his left knee.  Dr. Kruse diagnosed degenerative arthritis, a medial meniscus tear, and an intra-articular loose body.  After the employee and Dr. Kruse discussed both conservative and surgical treatment, the employee elected arthroscopic surgery.  For interim pain relief, Dr. Kruse administered a corticosteroid injection in the employee’s knee.  That injection provided some relief, but the employee continued to have problems with his knee function.

On April 12, 2007, Dr. Kruse performed surgery on the employee’s left knee.  According to his surgical note, Dr. Kruse detected a large amount of synovitis^[1] in the knee joint, a very large loose body comprised of cartilage and bone, and degenerative tearing in the medial meniscus, most significant in the posterior aspect.  Dr. Kruse surgically removed the loose body and debrided the medical meniscus “down to the stable margin,” in what he referred to as a “conservative partial medial meniscectomy.”

The employee testified that he continued to experience essentially the same level of pain following his surgery as he had noted before the surgery, and also experienced a restricted range of motion and swelling.  Dr. Kruse continued to restrict the employee from work, and recommended symptomatic treatment, including a knee sleeve, ice, pain medication and activity modification.  He also referred him for a repeat MRI of his left knee, which was performed on June 8, 2007.  That MRI showed a moderate chondromalacia in the medial joint compartment with a deep fissure in the medial femoral condyle, as well as mild lateral mild chondromalacia.^[2]  The reviewing radiologist noted degeneration and a subtle tear at the root of the medial meniscus, tricompartmental degenerative change, and effusion.

On June 13, 2007, the employee reported persistent knee pain.  On examination, Dr. Kruse detected weakness in the employee’s quadriceps and some atrophy.  Dr. Kruse administered a cortisone shot to the employee’s left knee.  He referred the employee for physical therapy, but the employee testified that he was only able to tolerate one session due to his knee pain.  Dr. Kruse also recommended an EMG of the femoral nerve, which had negative results.  Dr. Kruse recommended a second opinion and possibly a follow-up arthroscopic surgery for evaluation of residual meniscal pathology.

On September 4, 2007, Dr. Edward Szalapski examined the employee on behalf of the self-insured employer.  Dr. Szalapski concluded that the employee was, at the time of the examination, developing an arthritic knee.  He also concluded that the employee had a degenerative meniscal tear that was due to global degeneration of his knee and that was not related to his work injury.  In his opinion, the employee’s incident on April 2, 2007, was a temporary injury or aggravation of his arthritis and a temporary aggravation of his loose body in his left knee.  Dr. Szalapski also commented that the arthroscopic procedure which was performed only seven days after a steroid injection did not allow adequate time for that injection to take effect.  He would have recommended conservative treatment such as two steroid injections before recommending surgery.  Dr. Szalapski commented that “[i]n a knee such as [the employee’s], arthroscopy can actually prolong a recovery for an injury in some cases.”

Dr. Szalapski concluded that the employee would require additional medical care for his knee, and that he would “probably require a couple of aspirations and injections to alleviate his knee symptoms.”  He summarized his opinion concerning medical care, as follows:

On October 22, 2007, the employee consulted Dr. Jack Bert for another opinion.  At that time, the employee reported difficulty walking, including going up and down stairs, and difficulty bending his knee.  Dr. Bert concluded that the employee’s examination revealed “some rather classic findings for a torn cartilage,” and diagnosed a recurrent left knee medial meniscal tear.^[3]  He concluded that the employee’s meniscal tear had occurred as a result of his work injury; he explained that the type of tear detected in the employee’s left knee - - a horizontal cleavage tear of the posterior horn of the medical meniscus - - can occur with simple maneuvers, such as rotation with weight on the leg, just as occurred in this employee’s case.  To reduce the employee’s symptoms, Dr. Bert recommended additional surgery.

In a report dated October 31, 2007, Dr. Kruse responded to Dr. Szalapski’s opinions concerning future medical treatment, commenting that, in his opinion, the employee’s April 2007 injury continued to play a role in the employee’s symptoms.  Dr. Kruse stated that his opinion on whether the employee required additional medical treatment differed from that of Dr. Szalapski because he believed that the employee’s continued symptoms were at least in part related to his meniscal injury.^[4]  Dr. Kruse recommended an independent opinion from another orthopaedic surgeon to address whether the employee’s knee pain was meniscal or arthritic in nature.

On November 26, 2007, Dr. Bert performed a left knee arthroscopy on the employee’s left knee.  The surgery involved a subtotal resection of the left knee which involved removal of almost the entire back of the cartilage.

The employee testified that following this second surgery, his symptoms improved greatly.  The employee estimated that by approximately six weeks post-surgery, his knee symptoms had improved by 70 to 75 percent.  His pain diminished and he eventually regained his ability to climb and descend stairs.  The employee participated in physical therapy and used anti-inflammatories.  In early January 2008, because of swelling in the employee’s left knee, Dr. Bert removed some fluid from his knee and injected it with cortisone.  By January 28, 2008, Dr. Bert released the employee to return to work; he has continued to work since then.

The employee consulted Dr. Bert on March 13, 2008, reporting that he was doing much better but still noted mild pain.  Dr. Bert confirmed that he had detected arthrosis during the arthroscopic surgery, and recommended a series of Synvisc injections, described by Dr. Bert as an enzyme injected for the purpose of increasing the viscosity or thickness of the joint fluid and to help rejuvenate and replenish cartilage cells within the joint.  Dr. Bert explained that the purpose of the Synvisc injections was “to improve the arthritic condition of [the employee’s] knee that was visualized at the time of surgery.”  (Bert Depo., p. 14.)

The employee underwent the three recommended injections on March 13, March 24, and April 7, 2008.  He reported gradual improvement, and later estimated that these Synvisc injections provided approximately 95% recovery.  The employee has continued to experience occasional pain in his knee with walking or going upstairs, although he has continued to work without restrictions, in part because he is able to sit at work, and his work involves limited walking.

Following the employee’s left knee injury, the self-insured employer paid for ongoing medical treatment, including the first arthroscopic surgery performed in April 2007 by Dr. Kruse, as well as the second arthroscopic surgery performed in November 2007 by Dr. Bert.  The employer also paid temporary total disability benefits to the employee from April 5, 2007, through January 22, 2008.  The employer, however, has denied payment for the employee’s three Synvisc injections, denying that the employee’s 2007 injury represents a substantial contributing factor in his need for such treatment.

The employee’s health insurer paid for his Synvisc injections.  In December 2008, the employee filed a medical request seeking payment from the employer for the remaining Spaeth^[5]balance for the injections.  Following an administrative conference held to address the medical request, a mediator/arbitrator determined that the work injury was a substantial contributing factor to the employee’s need for the Synvisc injections.  The self-insured employer appealed that decision by filing a request for formal hearing.

The medical dispute was addressed at an evidentiary hearing held on June 11, 2009.  At the outset of the hearing, the parties stipulated that the employee sustained a work-related injury to his left knee on April 2, 2007, and that the three Synvisc injections were reasonable and necessary for the condition that was treated.  The issue at the hearing, therefore, was whether those injections were causally related to the employee’s April 2, 2007, injury.

In her Findings and Order issued on August 10, 2009, the compensation judge found the Synvisc injections to be causally related to the employee’s April 2, 2007, work injury.  She accepted the employee’s testimony that he had not experienced any physical problems with his work as a crane operator nor had any knee symptoms before his April 2007 injury, concluding that his testimony was consistent with the lack of references to his left knee in his earlier medical records.  The compensation judge concluded that the employee’s work injury had resulted in a torn meniscus and subsequent recurrent tear, as well as Grade II chrondromalacia.  She also found that the employee’s degenerative condition, as aggravated by the 2007 injury, necessitated the Synvisc injections.  The compensation judge relied on the opinion of Dr. Bert, that the employee’s need for the Synvisc injections was causally related to his 2007 work injury, and ordered the self-insured employer to pay for that medical treatment.  The employer 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).

The employer appeals from the compensation judge’s determination that the employee’s need for Synvisc injections was causally related to his 2007 injury.

The record contains conflicting medical opinions concerning the employee’s diagnosis and on the issue of causation.  The employee’s treating physicians, Drs. Kruse and Bert, as well as the employer’s expert, Dr. Szalapski, concurred that the employee had degenerative arthritis in his left knee prior to his injury on April 2, 2007.  Where their opinions diverged, however, was in how that injury affected the employee’s already arthritic knee and whether his later treatment, specifically the Synvisc injections, was causally related to his underlying arthritis or to his work injury.

The compensation judge relied on the opinion of Dr. Bert, who concluded that the employee’s work injury was a substantial contributing factor to the employee’s knee condition and need for treatment.  In Dr. Bert’s opinion, the employee’s injury caused a medial meniscal tear in his already arthritic knee, and the injury and tear aggravated the employee’s arthritis and necessitated both surgeries.  Dr. Bert remarked on the objective evidence supporting his opinion, including that the employee “was asymptomatic before the rotational injury which caused his symptoms, he had classic clinical findings on examination and he had a positive MRI immediately subsequent to this injury.”  Dr. Bert also stated that the Synvisc injections were intended to improve the arthritic condition visualized during surgery, as they would increase the viscosity in the knee joint and would rejuvenate and replenish cartilage cells within the joint.  In a letter dated January 2, 2009, Dr. Bert explained that

The compensation judge rejected Dr. Szalapski’s opinion that no causal link existed between the injury and need for Synvisc injections.  In Dr. Szalapski’s opinion, the employee did not have a discreet meniscal tear in his left knee but instead had pre-existing arthritis in his left knee.  He believed that the pre-existing arthritic condition resulted in a meniscal tear, and that the work injury itself did not result in a tear, nor did the work injury aggravate the underlying arthritis.  In Dr. Szalapski’s opinion, the employee’s incident on April 2, 2007, was a temporary injury or aggravation of his arthritis and a temporary aggravation of his loose body in his left knee.  As to the Synvisc injections, Dr. Szalapski testified that those were intended to treat the employee’s underlying arthritis, as opposed to any results of his work injury.

One of the reasons that the compensation judge was not persuaded by Dr. Szalapski’s opinion, that the 2007 injury was a trivial, temporary injury, was that the doctor’s opinion was predicated on his belief that the employee undoubtedly experienced left knee symptoms before his injury.^[6]  The judge found that assertion to be without a factual basis.  The employee testified that he had no left knee symptoms before his 2007 work injury, and there is no reference to left knee treatment in his earlier medical records.  This court typically defers to a compensation judge’s judgment concerning the credibility of witness testimony.  See Krotzer v. Browning-Ferris/Woodlake Sanitation Serv., 459 N.W.2d 509, 513, 43 W.C.D. 254, 260-61 (Minn. 1990).  In any event, although the parties dispute whether the employee noted left knee symptoms before his injury, there is no dispute that he had a pre-existing degenerative condition in his left knee.

The compensation judge found that the employee’s injury resulted in a torn meniscus and a subsequent recurrent tear, which required two arthroscopic procedures, and that the injury resulted in a grade 2 chondromalacia, and that the claimed Synvisc injections were causally related to the employee’s work injury.  The employer contends that the compensation judge reached that finding despite the overwhelming evidence that the employee had significant arthritis and degenerative changes in his left knee prior to his 2007 injury.  The employer argues that “[n]ot one doctor offered an opinion that the April 2, 2007 injury caused or resulted in the employee’s arthritis or, as the compensation judge phrased, it, his ‘grade 2 chondromalacia.’”

The employer also argues that the record contains no substantive evidence that the 2007 injury caused, aggravated, or accelerated the employee’s preexisting arthritis, citing to that portion of Dr. Bert’s testimony when he stated that he could not “say with 100 percent certainty” this had occurred.  Dr. Bert testified, at most, that the meniscal tear “could have” accelerated the employee’s arthritis “in a minimal way.”  (Bert Depo., pp. 52-53.)  The employer also argues that the compensation judge erroneously found that the three Synvisc injections the employee received are causally related to his 2007 work injury, as the record contains no support for these conclusions.  The employer points to testimony by Dr. Bert that the effects from any meniscus tear sustained acutely in the work incident had resolved by January 22, 2008, and that the Synvisc was administered to treat the employee’s osteoarthritis and not his meniscal pathology.

In response, the employee contends that the employer’s assertion, that no doctor offered an opinion that the work injury caused or resulted in the arthritis and/or Grade II chondromalacia, lacks merit.  The employee cites to Dr. Kruse’s opinion that the work injury aggravated and accelerated the employee’s underlying knee condition.  The employee also cites to Dr. Bert’s testimony that the surgical removal of more than 50% of the cartilage can cause underlying arthritis to progress, and that a meniscal tear in an already arthritic knee usually advances the arthritis.  The employee contends that the compensation judge’s conclusions are supported by the full scope of Dr. Kruse’s and Dr. Bert’s opinions and that the compensation judge’s reliance on those medical opinions should be affirmed.

There are both subtle and significant differences in the opinions of Drs. Kruse, Bert, and Szalapski.  Both Drs. Bert and Szalapski testified by deposition, during which they explained in detail their respective opinions on the employee’s underlying condition, the effects of his work injury, and the efficacy of medical treatment he received following that injury.  They concurred that the employee had an underlying arthritis or degeneration, as detected on his MRI scans and during surgery.  Where the doctors differed, however, was whether the injury had any effect on the employee’s ongoing medical condition, need for surgery and need for Synvisc injections.  The compensation judge chose Dr. Bert’s opinion over that of Dr. Szalapski.  While we understand the basis for the arguments set forth by the employer, we cannot say that the compensation judge erred in relying on Dr. Bert’s opinion and in concluding that the injections were compensable.

In rendering her opinion on causation, and on the causal relationship between the employee’s 2007 injury and his need for the Synvisc injections, the compensation judge accepted the opinion provided by Dr. Bert, and rejected the opinion provided by Dr. Szalapski.   In her memorandum, the compensation judge explained that

The compensation judge reviewed the various medical records and opinions, and specifically accepted Dr. Bert’s opinion that the employee’s 2007 work injury substantially contributed to his left knee condition and need for Synvisc injections.  It is the compensation judge's responsibility, as a trier of fact, to resolve conflicts in expert testimony.  In addition, “[w]here more than one inference may reasonably be drawn from the evidence, the compensation judge's findings shall be upheld.”  Nord v. City of Cook, 360 N.W.2d 337, 342, 37 W.C.D. 364, 371 (Minn. 1985).  As we have held in other cases as well, this court will generally affirm a compensation judge’s decision which is based on a choice between competing medical opinions.  Bode v. River Valley Truck Ctr., No. WC09-132 (W.C.C.A. Sept. 29, 2009).  All that is required, under the facts of the case when considered as a whole, is that a competent medical witness opined that the injuries causally contributed to the disabling condition.  See, e.g., Goss v. Ford Motor Co., 55 W.C.D. 316 (W.C.C.A. 1996); Darnick v. Swett & Crawford, slip op. (W.C.C.A. Oct. 29, 2002).  Here, Dr. Bert clearly expressed his opinion that the 2007 injury is causally related to the employee’s need for Synvisc injections.  Dr. Bert’s opinion was adequately founded, and the compensation judge could reasonably rely on that opinion.  In addition, Dr. Kruse’s opinion supports the compensation judge’s finding on causation.

We are mindful that there is evidence in the record that supports the arguments presented by the self-insured employer.  The record also contains evidence to the contrary.  The issue under this court's standard of review is not whether the facts will support findings different from those made by the compensation judge, but, rather, whether substantial evidence supports the findings of the judge.  Land v. Washington County Sheriff's Dep't, slip op. (W.C.C.A. Dec. 23, 2003) (citations omitted).  Because the compensation judge’s decision is supported by substantial evidence in the record, including expert medical opinions, we conclude that substantial evidence supports the compensation judge’s findings that there is a causal connection between the employee’s April 2, 2007, left knee injury and his current condition and need for the Synvisc injections.  Accordingly, we affirm those findings.