The employee appeals from the judge’s decision that she did not sustain a work-related injury to her left knee as claimed.  We affirm.

The employee was originally hired by Children’s Hospital [the employer] in 1980 to work as a service coordinator in the neonatal intensive care unit.  She subsequently held several other positions before obtaining a license as a registered nurse in 1998 or 1999.  She then worked for a short time as a float nurse and then in the employer’s pediatric unit before obtaining a nursing position in the pediatric intensive care unit [PICU].

As a nurse in the PICU, the employee works a three-week rotating schedule.  The cycle begins with 7:00 p.m. to 7:00 a.m. shifts on Friday, Saturday, and Sunday, followed by eight consecutive days off.  The employee then works the same 7:00 p.m. to 7:00 a.m. shifts Tuesday, Wednesday, and Thursday, has Friday through Sunday off, works Monday and Tuesday, and then has Wednesday and Thursday off before beginning the cycle again on Friday.  Payroll records indicate that the employee occasionally picks up extra hours, sometimes working 16-hour shifts.

The dispute in this matter concerns an injury the employee allegedly sustained to her left knee.  The employee testified that, at the end of a Sunday shift - - that is, around 7:00 a.m. on a Monday morning - - she tripped on a telephone cord in the break room immediately after punching out, falling and landing on her hands and her left knee.  The employee further testified that the pain in her left knee was excruciating and that she stayed on the floor for several minutes, waiting for a coworker to come and help her up.  When no one appeared, she pulled herself up and left the hospital.  The employee subsequently testified that she could not recall the date of the fall, but she was certain that the fall had occurred on a Monday morning and that she had been working with a nurse named Maureen Barrick during her just-completed Sunday evening shift.  If the employee’s recollection about these details is correct, hospital schedules and payroll records establish that the alleged incident could only have occurred on the morning of Monday, March 22, 2004.

The employee was off work, as scheduled, for the next eight days.  The employee testified that her knee hurt during that period but that she believed that “it would work itself out,” and she did not seek treatment or notify anyone at the employer of the incident.  She reported for her next shift, as scheduled, on Tuesday, March 30, 2004, at about 3:00 p.m. and worked until about 7:00 a.m. the following morning - - a 16-hour shift.  While she testified that she called in sick for her next shift, because “the knee was swelling up and creating more pain,” payroll records indicate that she worked a 12-hour shift, as scheduled, on March 31, 2004.  Following her completion of that shift, on the morning of April 1, 2004, the employee had a performance review with Sue Selz, the nurse manager of the PICU.  Ms. Selz testified that she did not see the employee limping, and it is undisputed that the employee did not inform Ms. Selz of her alleged fall in the break room during this meeting.

For her regularly-scheduled April 1, 2004, shift, the employee was instead on call and apparently was not called into work.^[1]  The employee was scheduled to work but was on call again on April 5, 2004; called in sick on April 6, 2004; worked her scheduled shift on April 9; was “absent” on April 10, 2004; was on call on April 11, 2004; worked on April 20, 2004; and called in sick on April 21, and April 22, 2004.  The employee testified that, as time went on, she became unable to work two shifts in a row due to her knee pain and that, when she called in for a “requested absence day,” she was told that she could be placed on call, instead.  She further testified that it did not seem ethical to be on call if she was not physically able to handle the work, so she decided to seek care at the employer’s Employee Occupational Health Service.  She also testified, however, that another supervisor, Adrian Thornton-Felix, had instructed her to go to Occupational Health, sometime before this, after seeing her limping at work.
The employee was seen by a nurse in Occupational Health on the morning of April 22, 2004.  The employee testified that, when she told the nurse that she was unsure of the date of injury, the nurse replied that she should simply pick a date, which could be changed later.  The employee also testified that she informed the nurse of the incident in the break room.  The nurse apparently told the employee that she needed to be seen by a physician, and the employee was consequently seen by Dr. N. Westhoff on the same date.  The history portion of Dr. Westhoff’s treatment record contains a description of the employee’s alleged fall in the break room and indicates that the incident occurred on April 6, 2004.  Dr. Westhoff advised the employee to use a brace as well as ice or heat, along with Ibuprofen and Flexeril, and he scheduled an MRI scan.

On April 28, 2004, the employee underwent an MRI scan of her left knee, which revealed degenerative changes of the medial compartment, degenerative-type fraying and irregularity along the inner margins and undersurface of the posterior horn of the medial meniscus, and minimal joint effusion.

The employee returned to see Dr. Westhoff on May 3, 2004.  At that time, the employee was referred for six physical therapy sessions and restricted to sedentary work.  Dr. Westhoff wrote that the employee’s degenerative joint disease was a “preexisting condition, but was aggravated by the work incident.”

A few days later, on May 6, 2004, the employee was seen by Dr. Salman Shafiq, her family practice doctor.  Dr. Shafiq’s office note describes the employee’s alleged fall in the break room at work “on 3/21/04.”  After reviewing the MRI scan, Dr. Shafiq advised the employee to see Dr. Wesley Peters for an opinion on the advisability of arthroscopic surgery.

On May 18, 2004, the employee was seen by Dr. Peters, who again recorded a history of the alleged fall in the employer’s break room “on 03/21.”  Dr. Peters diagnosed degenerative joint disease with osteoarthritis, writing that “[t]his is a longstanding issue even though it did not hurt before and she may have exacerbated the pain level with her injury, but the mechanism of injury did not cause the osteoarthritis.”

Conservative treatment was ultimately unsuccessful, and, on July 27, 2004, the employee underwent surgery, in the nature of a left total knee arthroplasty.

In September of 2004, the employee was examined by Dr. Paul Dworak, the employer’s independent examiner.  In his report, Dr. Dworak indicated that the employee had “repeatedly stated that the injury occurred in June of 2004."  After noting discrepancies in the employee’s account of events, Dr. Dworak wrote as follows:

The employee claimed entitlement to various benefits as a result of an alleged work-related injury to her left knee, and the matter came on for hearing before a compensation judge on August 4, 2005.  As of the date of hearing, various dates of injury had been alleged, including March 21, 2004, March 22, 2004, March 31, 2004, and April 6, 2004.  However, at the beginning of the hearing, the employee’s counsel clarified that the alleged injury had most likely occurred on March 21, 2004.  The employer denied primary liability.  Witnesses included the employee and Sue Selz, the employee’s supervisor.  The parties also submitted deposition testimony from Dr. Peters and Dr. Dworak.^[2]

In a decision issued on October 13, 2005, the compensation judge concluded that the employee had not sustained a work-related injury to her left knee as claimed.  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 (2004).  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).

In denying the employee’s claim, the compensation judge evidently concluded that the employee’s account of her alleged fall in the break room was not credible.^[3]  On appeal, the employee contends that “there is no evidence opposing the fact that [the employee] injured her left knee at work,” alleging that “there is absolutely no evidence, medical or otherwise, to show that the injury happened other than how [the employee] has explained.”  Accordingly, the employee contends, the compensation judge’s decision is not supported by substantial evidence in the record as a whole.  We are not persuaded.

From her findings and memorandum, it is evident that the compensation judge was troubled by discrepancies in the employee’s reports as to the date of the alleged injury - - ranging from March 21 to “June of 2004" - - and by errors in the employee’s testimony regarding the dates she actually worked after the injury.  In addition to these discrepancies, the compensation judge noted that the employee had testified that her knee was so sore by April 1, 2004, that she had an observable limp, yet Ms. Selz did not observe the limp when the employee walked the short distance into and out of her office for her performance review on that date.  Moreover, the employee did not inform Ms. Selz of the injury at that time.  And, despite her claim that, by that point, she was experiencing swelling, increasing pain, and the limp, the employee did not seek treatment for her left knee symptoms for another three weeks.

Physicians agree that the employee had longstanding degenerative changes, or severe osteoarthritis, disclosed by the April 28, 2004, MRI scan, that was not caused by the alleged fall at work.  The issue is whether the fall occurred as claimed, and, if so, whether the fall substantially aggravated the employee’s underlying condition.  Both Dr. Dworak and Dr. Wesley agreed that the MRI scan showed no evidence of acute injury, and Dr. Dworak testified that evidence of acute injury^[4] would have been “most likely” had the employee experienced a major fall.  Dr. Dworak also suggested that he would not have expected the employee to have worked 12-hour shifts after the alleged fall if the fall had substantially exacerbated the employee’s underlying arthritis.  As Dr. Dworak put it, “most people, you know, don’t work 12-hour shifts if they’re having acute pain.”

We see this as a close case.  As the compensation judge herself acknowledged, the employee had plausible explanations for her initial failure to seek treatment or give notice of injury.  Moreover, the employee’s description of the alleged incident in the employer’s break room was consistent throughout medical and employment records and in her testimony at hearing.  The fact remains, however, that the alleged March 22, 2004, incident was unwitnessed, the employee worked long shifts, on her feet, as scheduled, on March 30 and March 31, 2004, and she did not notify her supervisor of the incident during her performance review the morning of April 1, 2004, despite allegedly worsening symptoms.  Furthermore, the employee offered no testimony to corroborate her claim that she had developed an observable limp by that time.  As for the employee’s claim that “[s]omething caused [her] knee to become symptomatic, which in turn necessitated the need for the surgery,” we would observe that Dr. Dworak’s testimony and report would support the conclusion that the employee’s symptoms and need for surgery were simply the result of a natural progression of the employee’s underlying osteoarthritis.  That is, this is not a case in which there is no other explanation for the employee’s condition.

Credibility determinations are generally for the compensation judge to make.  See Even v. Kraft, Inc., 445 N.W.2d 831, 42 W.C.D. 220 (Minn. 1989).  In the present case, given all the circumstances, we cannot conclude that the compensation judge erred in rejecting the employee’s testimony as to the occurrence of the alleged work injury.  The fact that another judge might have decided the matter differently provides no grounds for reversal.  We therefore affirm the judge’s denial of the employee’s claim.