The employee appeals from the compensation judge's denial of compensation for an injury sustained at home allegedly consequent to his work injury.  We affirm.

This is a complex and very close case.  In 1992 or 1993, Robert Kidd injured his right knee while skiing, an injury that required surgical repair of the anterior cruciate ligament in that knee.  Three or four years later, in September of 1996, Mr. Kidd, in the course of his work as a journeyman industrial painter for TMI Coatings, sustained a work-related injury to his left knee, shortly thereafter undergoing surgical reconstruction of the anterior cruciate ligament [ACL] also in that knee.  On May 12, 1997, as a result of this latter left-knee injury, Texas physician Dr. David Henges rated the employee’s permanent partial disability of the body as a whole at 5%:  3% related to ACL laxity and 2% related to collateral ligament laxity.^[1]  For at least three years after this injury, Mr. Kidd experienced buckling and popping and instability in the knee, all of which made it difficult for him to squat or to bend or to work on ladders.  On June 3, 1999, Mr. Kidd underwent an independent medical evaluation by Dr. Peter Daly.  Dr. Daly reported that Mr. Kidd was continuing to complain of left knee stiffness, intermittent buckling and swelling, and an intermittent popping sensation over the anterior patellar area.  He diagnosed status post left knee ACL reconstruction with mild residual laxity of both the ACL and the medial collateral ligament, concluding that Mr. Kidd’s condition was permanent and that he was at maximum medical improvement.  The employee subsequently worked in a coffee shop for about a year and then returned to working as an industrial painter, seeking no further treatment for his knee for about six years.

On October 17, 2006, about ten years after his left ACL injury and reconstruction, Mr. Kidd sustained fractures to his left tibia and fibula when he fell in the course of his work as a journeyman painter with Xcel Energy.  Mr. Kidd [the employee] was thirty-five years old on that date and was earning a weekly wage of $1,186.00.  The employee was treated for his injury by Dr. Steven Mulawka, who, on the date of the injury, set the fractures in a surgical operation, the tibial fracture requiring placement of a rod that extended from just below the employee’s knee through the level of the fracture.  Xcel Energy [the employer] acknowledged liability for the injury and commenced payment of benefits.  For two weeks following the employee’s surgery, the injured leg was in a full-leg, groin-to-ankle cast, and the employee was restricted from putting any weight on it; for six to eight weeks thereafter the leg was cast in a knee-high “boot splint,” and the employee was released to put only limited weight on it.

About this time, evidently on December 11, 2006, the employee transferred his primary care from Dr. Mulawka to Dr. Paul Havel.  Dr Havel noted on December 28, 2006, that x-rays on that date revealed good consolidation of the employee’s fractures, contrary to what Dr. Havel had seen on x-rays two weeks earlier.  Dr. Havel prescribed physical therapy, to commence January 15, 2007, and released the employee to return to primarily sedentary work, which he evidently performed for the employer for about three weeks.  The employee continued to have pain, in both legs now, particularly in his right leg.  In late January 2007, the employer evidently informed the employee’s QRC that the employee had been missing work for two days, and, after being queried by the QRC, the employee attributed his absence to his right knee pain.  The employer thereupon evidently instructed the employee to stay off work until he was more fully recovered.

On February 19, 2007, the employee complained to Dr. Havel that he also had some pain in and around the incision area of his left knee and sometimes pain radiating down the back of his left leg, but he indicated that he was still more concerned about his right knee.  Dr. Havel noted the employee’s right knee ACL reconstruction fourteen years earlier, concluding that “at this point [the right knee] does not appear to be involved in [the employee’s] work comp case.”  Dr. Havel ordered an MRI of the right knee, and, at the employee’s indication that he was “having problems with his work activities and wanted to know if he could be off for a week,” he once again restricted the employee from working.  On March 22, 2007, about five months after his work injury, Dr. Havel noted that “[a]t this point the fracture is healed and the leg is stable,” although “[h]e is still having problems with strength, pain and balance issues and has not reached his maximum improvement.”  Dr. Havel ordered work-hardening therapy, about two hours a day three or four times a week.

The employee commenced work hardening on March 29, 2007, with occupational therapist Gretchen Welshons.  In her initial assessment of the employee, Ms. Welshons noted in part that the employee’s “left knee is strong in flexion and extension, but he has only a fair quad set.  Circumference of the left quad is significantly smaller as compared to the right.  There is also weakness in the left hip flexors.”  Ms. Welshons went on to state further on that date that the employee “does not have sufficient strength or range of motion in the left lower extremity for functional squatting.  He demonstrates an antalgic gait pattern that increases when he is carrying, climbing stairs or walking on angled surfaces.”  By April 23, 2007, however, the employee had made “steady gains in functional strength and endurance” and had “improved range of motion in his left knee,” though he did have “moderate swelling of the left lower leg” and some “difficulty with squatting to the floor due to ankle limitations in range of motion.”  By May 16, 2007, Ms. Welshons’s records indicate that the employee was “feeling stronger in general,” that “[w]alking and standing all day is fine,” that “[h]is left knee range of motion and strength is now comparable to the right knee,” and that even “[g]oing up stairs is OK.”  She reported also, however, that “[h]e still gets pain on the inside of the left knee, under the cap,” that he has some “‘shaking’ . . . when on the ladders,” and that “[h]is left knee continues to demonstrate slight weakness when descending on stairs,” where it “wants to buckle.”

On May 27, 2007, the employee was walking down some stairs in his home when his left knee buckled and he fell.  As a result of the fall, the employee sustained a left lateral tibial plateau fracture.  He saw Dr. Havel on May 29, 2007, who, noting the employee’s work injury and tibial rodding, ordered a CT scan “so we can best assess the degree of involvement.”  On June 5, 2007, the employer, which had been paying temporary total disability benefits, filed a notice of intention to discontinue [NOID] benefits, on grounds that the employee’s fall at home was a superseding intervening cause of the employee’s ongoing disability.  On June 7, 2007, the employee saw Dr. Havel again, whose treatment notes on that date read in part as follows:

An administrative conference on the employer’s NOID was held on June 29, 2007, pursuant to which an order was issued, on July 2, 2007, denying the employer’s request to discontinue benefits, on grounds that “[w]hile this is not the clearest of medical opinions, Dr. Havel seems to be saying that while the rod in the knee was not the cause of the fracture, the knee buckling which was clearly evident in physical therapy prior to the fracture and the quadriceps atrophy were the result of the initial admitted injury.”  The employer filed a petition to discontinue benefits on August 7, 2007.  On October 3, 2007, the employee filed a medical request, alleging entitlement to reimbursement of  $5,349.05 in medical expenses, most of which related to his injury at home on May 27, 2007, consequent to his work injury on October 17, 2006.

On October 6, 2007, the employee was examined for the employer by orthopedist Dr. Gary Wyard.  In his comprehensive eleven-page report on October 8, 2007, Dr. Wyard concluded in part that the employee’s injury at home on May 27, 2007, was not a direct consequence of his work-related injury on October 17, 2006.  He noted the employee’s preexisting problems with his left knee as a result of his ACL tear and reconstruction in 1996 and that “[the employee] clearly has instability of the left knee on clinical examination related to that injury,” noting further that the employee also had a milder instability in his right knee as a result of his 1993 skiing injury and ACL reconstruction.  He concluded that the employee’s “[k]nee buckling and shakiness is a result of [his] anterior cruciate ligament reconstruction and there is no reason that he should have any subjective complaints with regard to his knee as a result of the October 17, 2006, injury . . . which has healed.”

On October 15, 2007, Dr. Havel testified by deposition. Central to his testimony was his opinion

On that same date, October 15, 2007, occupational therapist Welshons also testified by deposition.  She testified in part that, when she first saw the employee on March 29, 2007, he was having weakness in his left knee and quadriceps, the left quadriceps being visibly smaller than the right, together with some limitation in his ankle, some weakness in the left hip flexors, and some trouble with balance.  She testified also that on May 8, 2007, the employee had had some difficulty with stair-climbing exercises and some buckling of his left knee descending the stairs, problems that he continued to complain of on May 16 and subsequent sessions as well.  On cross-examination Ms. Welshons testified that some difference in size between a person’s quadriceps is not uncommon.

The matter came on for hearing on November 14, 2007.  Issues at hearing included whether or not the employee’s October 2006 work injury was a substantial contributing factor in the employee’s temporary total disability continuing from June 6, 2007, and whether or not the employee’s medical expenses since May 27, 2007, were causally related to that October 2006 work injury.  Evidence submitted at hearing included the testimony of the employee.  In the course of his testimony, the employee was asked by his attorney, “From 2000 until your injury in 2006 did you have any sensation of a giving out or a buckling sensation in your left knee?”, to which the employee replied, “Occasionally.  I mean, as the years go on your leg seems to get stronger so I would say in the early part of the years there was some instability but it seemed to - - I didn’t think about it by 2006.”  By findings and order filed November 29, 2007, the compensation judge concluded in part that the employee had failed to prove that his fall on May 27, 2007, was a consequence of his October 17, 2006, work injury or that his current restrictions were causally related to that injury.  She explained in her memorandum that, while the employee’s causation theory, that his leg gave out on the stairs at home in May 2007 due to loss of leg strength consequent to his October 2006 work injury, was not inconceivable, she considered it “at least equally likely that the employee’s knee buckled as he descended the stairs at home because of a preexisting laxity in the ligaments of his left knee that had nothing to do with a loss of strength attributable to the October 2006 work injury.”  On those conclusions, the judge granted the employer’s petition to discontinue benefits and denied and dismissed with prejudice the employee’s medical request filed October 3, 2007.  The employee appeals.

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 Food 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.

The compensation judge concluded that the employee’s October 2006 work-related left tibia and fibula fractures were not a substantial contributing cause of his May 2007 fall down the steps at home and consequent refracture of his left leg.  Emphasizing that his burden at hearing was not to prove that his 2006 work injury was the sole cause of his 2007 injury at home but only to prove that it was a substantially contributing cause of that injury,^[2] the employee contends that the judge’s conclusion in this case is clearly erroneous and unsupported by substantial evidence, in that it “lacked adequate foundation and ignored the substantial evidence” supporting a contrary conclusion.  This is a very close case, but we are not persuaded.

We reiterate initially here that, under our standard of review, the issue on appeal is not whether there is substantial evidence to support a factual conclusion contrary to that reached by the compensation judge but whether there is substantial evidence to support the conclusion reached by the judge.  See Land v. Washington County Sheriff’s Dep’t, slip op. (W.C.C.A. Dec. 23, 2003); see also Ludford v. Honeywell, Inc., slip op. (W.C.C.A. Mar. 17, 2004); Moe v. Dr. Matthew A. Gahn, slip op. (W.C.C.A. Dec. 31, 2003); Redgate v. Sroga’s Standard Serv., 421 N.W.2d 729, 734, 40 W.C.D. 948, 957 (Minn. 1988).  Nevertheless, although this standard does imply important deference to the compensation judge as factfinder, we acknowledge that this court is not to look “only at the evidence which supports the Compensation Judge's findings, but also at the opposing evidence . . . .  The evidence, in a sense, is weighed to determine its substantiality.”  Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239 (underscoring added).  Therefore, given especially the fact that, as we have stated twice earlier, we find this a very close case, we will, in the course of our discussion here, address major elements of evidence cited by the employee that would have supported a decision contrary to that reached by the judge.  We must do so, however, giving “due weight to the opportunity of the Compensation Judge to evaluate the credibility of witnesses” appearing before her, id. at 59-60, 37 W.C.D. at 239-40, and always bearing in mind that the issue is not whether we would have reached a different conclusion than that reached by the judge but whether the conclusion reached by the judge is “supported by evidence that a reasonable mind might accept as adequate,” id. at 60, 37 W.C.D. at 240.

The employee argues that Dr. Havel’s records two months before the employee’s fall down stairs at home in May 2007 document the fact that the employee was at that time “having problems with strength, pain and balance issues.”  On that same date, however, March 22, 2007, Dr. Havel also noted that “[a]t this point the fracture is healed and the leg is stable” (underscoring added).  The employee argues further that Dr. Havel clearly opined in his October 2007 deposition that quadriceps weakness stemming from the employee’s work injury was the cause of the employee’s May 2007 fall down the stairs at home.  In that same deposition, however, Dr. Havel also acknowledged that it was possible that the leg buckling that apparently resulted in the employee’s May 2007 fall down the stairs was related to the same leg buckling symptoms that the employee was complaining of from 1996 through 1999.  These were symptoms consequent to his 1996 ACL injury and reconstruction, a condition that has been rated as a 5% whole-body impairment and one that Dr. Daly declared in 1999 to be permanent and unlikely to improve.  This concession by Dr. Havel, in light of Dr. Daly’s 1999 opinion, renders not at all unreasonable the compensation judge’s decision to rely instead on Dr. Wyard’s unequivocal opinion on October 8, 2007, that the knee buckling and shakiness that apparently resulted in the employee’s fall at home on May 27, 2007, were a consequence of the employee’s 1996 ACL injury and reconstruction and not of his recovery from his October 2006 leg fracture at work.

The employee contends also that there was no evidence to support the compensation judge’s conclusion in Finding 5 that the employee had occasional left knee buckling and instability from 2000 to October 2006 or her conclusion in Finding 8 that the employee’s left knee strength was comparable to his right knee strength on May 16, 2007.  With regard the contention as to Finding 5, we would refer the employee to his testimony transcribed on page 23 of the hearing transcript, to the effect that such symptoms did occur “[o]ccasionally” during that period, that instability specifically persisted at least through the early part of those years, and that by 2006 he simply “didn’t think about it.”  The employee presumes that the judge’s conclusion in Finding 8 as to equal knee strength on May 16, 2007, was based on Ms. Welshons’ observation that the employee’s left knee strength was “within normal limits” on that date, which the employee maintains is not a conclusion that the two legs were of equal strength on that date.  We note, however, that Ms. Welshons did expressly state on May 16, 2007, that the employee’s “left knee range of motion and strength is now comparable to the right knee” (underscoring added).^[3]  The employee suggests further that the judge’s finding also ignores substantial other of Ms. Welshons’ reports on that same date that support the employee’s position that his knee was at that time weak and unstable - - namely that the employee had pain under his left knee cap, that his left knee was still weak or shaky when he was on ladders, that it continued to want to buckle when he came down stairs.  On that same date, however, Ms. Welshons also reported that the employee was as of that date “feeling stronger in general,” that “[w]alking and standing all day is fine” for him, and that even “[g]oing up stairs is OK.”  The judge’s finding that the employee’s left knee strength on May 16, 2007, was comparable to his right knee strength is directly and expressly supported by Ms. Welshons’ records, and there is clearly evidence also, if less direct, to support a conclusion that the employee’s leg stability was improving - - whatever might have been the cause of its earlier instability.

In paragraph 3 of her memorandum, the compensation judge reasons as follows:

Finally, the employee argues that nowhere does the judge discuss the “obvious atrophy” evident in the employee’s left quadriceps, contending that “[t]here was no medical opinion, testimony or report offered by the employer to dispute Dr. Havel’s conclusions” as to that atrophy’s causal role in the employee’s fall on May 27, 2007.  We conclude, however, that the judge sufficiently addressed that issue (1) in Finding 8, in which she concluded, on substantial evidence in the records of Ms Wolshons, that, “[a]s of May 16, 2007, the employee’s left knee strength was comparable to his right knee,” (2) in her reiteration of that conclusion in the fourth paragraph of her memorandum, and (3) in her discussion, on page five of her memorandum, of Dr. Havel’s opinion as to atrophy’s very role in this case.  Based presumably on Ms. Welshons’ records as to equality of the employee’s knee strength on May 16, 2007, and also perhaps on Ms. Welshons’ testimony that, at any rate, some difference in size between a person’s quadriceps is not uncommon, the compensation judge concluded her assessment of Dr. Havel’s causation theory by “also question[ing] the foundation on which Dr. Havel’s opinion is based as there is no showing that the employee had atrophy at the time of the May 27, 2007 fall.”  And Dr. Wyard’s October 8, 2007, opinion is clear expert medical evidence in support of that conclusion of the judge.

As we stated earlier, this is a very close case, and there does exist substantial evidence to support either decision available to the compensation judge.  However, concluding that it was not at all unreasonable, we affirm the judge’s conclusion that the employee’s October 17, 2006, work injury was not a substantial contributing factor in his nonwork-related injury on May 27, 2007.  See  Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.