The self-insured employer appeals from the compensation judge’s findings that the employee sustained a work-related injury to his right knee on or about August 23, 2012; that the October 5, 2012, incident was a continuing manifestation of the August 23, 2012, work injury; that the employee provided timely notice of the August 23, 2012, injury; and that the employee has not yet reached maximum medical improvement (MMI) from the effects of the August 23, 2012, work injury.  We affirm.

The employee, Randy C. Orth, was a dock worker and driver for the self-insured employer, ABF Freight Systems, Inc.  His job included unloading and loading truck trailers at the freight terminal and picking up freight from and delivering freight to customers.  The employee testified that on about August 23, 2013, he opened the terminal and began unloading trailers.  He stated he was on a forklift moving a pallet when the front boxes started to tip.  The employee testified he turned to slide off the forklift seat and struck his right foot against the wall of the trailer bending it to the right.  He got down and into the trailer and pushed the boxes back on the pallet.  While stepping back up onto the forklift, a distance of approximately 19 to 22 inches, he felt a “hot spike” from above the right knee and down the leg.

Later that morning, the employee testified he went down to the office of Jeff Schomel, his supervisor, and, in between phone calls, told Mr. Schomel he had just injured his leg.  The employee testified that Mr. Schomel noticed he was limping the next day, and he reminded his supervisor that he had told him about the incident the day before in his office.  By deposition, Mr. Schomel testified he did not recall a conversation in August 2012 in which the employee told him that something had happened to his leg at work.  However, he also testified that he had no reason not to believe the employee’s statement, just that he could not remember it.  Mr. Schomel further testified that the employee was a very hard-working, honest employee, and that he put a lot of trust in him.  He described the terminal manager’s job as very stressful, and stated it could have been very busy when the employee came to talk to him.  He additionally testified that at least a week or two before October 5, 2012, he saw the employee limping, and that the employee had told him he was going to a clinic to get his knee checked.

The employee stated that following the incident, the pain and swelling in his right knee progressively worsened.  He made an appointment to see his family physician, Dr. Christopher Wenner, who saw the employee on September 27, 2012.  The employee reported several weeks of right knee pain, worse with walking and getting in and out of his truck.  The doctor noted pain laterally on palpation and limited flexion.  Dr. Wenner prescribed Ultram, ice, and rest.

On October 5, 2012, the employee was making his second delivery of the day.  While walking back to his truck across a paved parking lot, the employee suddenly felt his right knee snap and felt immediate extreme right knee pain.  He contacted his supervisor at the terminal, drove the truck back, and was immediately taken to the St. Cloud Hospital emergency room.  The emergency room doctor took a history of subacute knee pain for the past three months, prescribed Vicodin, gave him a knee immobilizer and crutches, and advised him to follow up with an orthopedist.

The employee was seen by Dr. Geiser, an orthopedist, on October 8, 2012.  The employee described onset of knee pain while walking in a parking lot on October 5, 2012.  He reported occasional discomfort in the knee prior to that time, but never that significant.  On examination, the employee had a significant right antalgic gait, moderate effusion, and localized pain along the medial joint line.  An MRI scan on October 11, 2012, showed tearing of the posterior horn of the medial meniscus, moderate chondromalacia, and a mild chronic-appearing sprain of the proximal medial collateral ligament.  On November 15, 2012, Dr. Geiser performed an arthroscopic examination and partial medial meniscectomy of the right knee.  The employee continued to experience right knee pain and stiffness post-surgery, particularly with weight bearing and activity.

The employee became frustrated with his lack of improvement, and, in March 2013, Dr. Wenner provided a referral to Dr. Philip Prosapio, an orthopedic surgeon, for a second opinion.  The employee was seen by Dr. Prosapio on April 10, 2013.  He gave a history of an injury at work on or about August 26, 2012, when he got off a forklift and landed funny, and then reinjured the knee at work on October 5.  An MRI scan on March 30, 2013, showed a possible new meniscal tear with medial joint line degenerative arthritis.  Options for treatment were discussed including lateral heel wedges, an unloading brace, weight loss, corticosteroid injections, and hyalonic acid (rooster comb) injections.  Total knee replacement would be indicated in the future if the employee did not obtain pain relief.  Dr. Prosapio continued to treat the employee through the date of the hearing.

Dr. Guy Rudin, an orthopedic surgeon, saw the employee on August 1, 2013, at the request of the employer.  Dr. Rudin diagnosed non-work-related degenerative arthritis of the medial and patellofemoral compartments of the right knee associated with a degenerative tear of the medial meniscus.  He concluded the medical records were inconsistent with the August 2012 mechanism of injury described by the employee, and, in any event, believed the more significant of his symptoms occurred on October 5, 2012.  Dr. Rudin did not believe either of the incidents caused anything more than a temporary increase in symptoms from pre-existing, non-work degenerative changes in his right knee.  The doctor further opined the employee was at MMI as of the date of Dr. Prosapio’s initial evaluation on April 10, 2013.

In a deposition on September 30, 2013, Dr. Prosapio testified that, in his opinion, the employee sustained a work-related right knee injury on or about August 23, 2012, in the nature of a torn meniscus and/or exacerbation of a pre-existing degenerative right knee condition causing the knee to become symptomatic, and that the October 5, 2012, incident was a continuing manifestation of the August 23, 2012, injury.

The employee filed a claim petition alleging work injuries to his right knee on August 23, 2012, and October 5, 2012, and seeking temporary total disability benefits and payment of medical expenses.  The self-insured employer denied primary liability for both dates and additionally asserted the employee did not provide timely notice of an August 23, 2012, injury.  The case was heard by Compensation Judge Rolf G. Hagen on October 17, 2013.  In a Findings and Order, served and filed December 13, 2013, the compensation judge found that (1) the hearing testimony of the employee was credible; (2) the employee sustained a work-related injury to his right knee on August 23, 2012; (3) the employee provided timely notice of the August 23, 2012, injury to his supervisor; (4) the incident on October 5, 2012, was a continuing manifestation of the August 23, 2012, work injury; and (5) the employee had not yet reached MMI from the effects of the August 23, 2012 work injury.  The self-insured employer appealed.

The self-insured employer asserts that an employee seeking benefits must prove the claim by a preponderance of the evidence.  Quoting from Dille v. Knox Lumber, 452 N.W.2d 679, 42 W.C.D. 819 (Minn. 1990), the employer maintains that when two opposing inferences can be drawn with equal justification, it cannot be said that one preponderates over the other, and, in that event, the party having the burden of proof must lose.  The employer argues a preponderance of the evidence does not support the judge’s decision and the compensation judge improperly shifted the burden of proof to the employer.  The employee, on the other hand, argues that substantial evidence supports the findings of the compensation judge and, as such, the findings must be affirmed.

Pursuant to Minn. Stat. § 176.021, subd. 1a, “[a]ll disputed issues of fact arising under this chapter shall be determined by a preponderance of the evidence.”^[1]  This standard is imposed upon the trier of fact in deciding the case.  In reviewing cases on appeal, however, this court must instead 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.  It is well established that where more than one inference may reasonably be drawn from the evidence, the inferences drawn by the factfinder may not be disturbed on appeal.  Dille, id.; Hengemuhle v. Long Prairie Jaycees, 358 N.W.2d 54, 60, 37 W.C.D. at 240.  It is not the role of this court to make our own evaluation of the probative value of the evidence and testimony submitted.  Whether we might have viewed the evidence differently is not the point, but whether the findings of the compensation judge are supported by evidence that a reasonable mind might accept as adequate.  Redgate v. Sroga’s Standard Serv., 421 N.W.2d 729, 40 W.C.D. 948 (Minn. 1988).

The self-insured employer asserts the only evidence that supports the compensation judge’s finding that the employee sustained an injury on or about August 23, 2012, is the employee’s uncorroborated testimony, and argues the evidence is not sufficient to support the compensation judge’s decision.  The employer argues that great weight should be given to contemporaneous medical records, and contends that none of the employee’s initial medical providers provided a history of a specific precipitating incident in August 2012.

The compensation judge, in an unappealed finding, found the testimony of the employee credible (finding 2), and accepted the employee’s testimony regarding the occurrence of an injury on or about August 23, 2012.  While the initial treatment records do not contain a specific history of the mechanism of injury, they do include a history of an onset of knee symptoms approximately three weeks before his visit with Dr. Wenner on September 27, 2012.  Assessment of a witness’s credibility is a unique function of the trier of fact and this court must give due weight to the compensation judge’s opportunity to assess the credibility of witnesses.  Even v. Kraft, Inc., 445 N.W.2d 831, 834, 42 W.C.D. 220, 225 (Minn. 1989); Brennan v. Joseph G. Brennan, M.D., P.A., 425 N.W.2d 837, 41 W.C.D. 79 (Minn. 1988).  Consequently, this court will generally defer to a compensation judge’s credibility determination.  Murphy v. Anoka Drug & Gifts, 63 W.C.D. 158 (W.C.C.A. 2002); McLafferty v. RS Eden, No. WC07-218 (W.C.C.A. Feb. 4, 2008).

In addition to the employee’s testimony, the compensation judge adopted the opinions of the employee’s current treating orthopedist, Dr. Prosapio, finding them more persuasive than those of the IME, Dr. Rudin.  The competence of a witness to render expert medical testimony depends on both the degree of the witness’s scientific knowledge and the extent of a witness’s practical experience with the matter at issue.  Reinhardt v. Colton, 337 N.W.2d 88, 93 (Minn. 1983).  Foundation may be established by personal knowledge, a hypothetical question, or testimony at the hearing.  Scott v. Southview Chevrolet, 267 N.W.2d 185, 188, 30 W.C.D. 426, 430 (Minn. 1978); Kelsey v. Lovegreen Indus. Servs., No. WC07-159 (W.C.C.A. Dec. 12, 2007).  Dr. Prosapio based his opinion on the history he obtained from the employee, a hypothetical question, and his examination and treatment of the employee.  As such, Dr. Prosapio had sufficient foundation for a medical opinion.  See Grunst v. Immanuel-St. Joseph Hosp., 424 N.W.2d 66, 40 W.C.D. 1130 (Minn. 1988).

Dr. Prosapio opined the employee sustained a work-related injury on or about August 23, 2012, and that the October 5, 2012, incident was a continuing manifestation of the August 23, 2012, work injury.  The doctor observed the employee did not have any symptoms or treatment for knee problems prior to August 2012.  He explained that when someone is stepping up or down from a height, or twists a knee, it can put extreme pressure between the femoral condyle, the femur bone, and the tibia.  The meniscus can get caught between the top and bottom bones as you torque or rotate and it can tear.  Dr. Prosapio believed that is what probably happened on August 23, 2012.  Then, in early October, Dr. Prosapio suspected that the torn meniscus or other degeneration in the knee had progressively worsened, and a portion of the meniscus was caught between the upper bones and retore.  It is the function of the compensation judge to consider competing medical opinions and a decision based upon a medical opinion with adequate foundation will generally be affirmed by this court.  See Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 363 (Minn. 1985); Nitz v. Abbott Northwestern Hosp., 64 W.C.D. 191 (W.C.C.A. 2004); Koppen v. Knowlan’s Supermarket, 71 W.C.D. 99 (W.C.C.A. 2011).

This issue presents a fact question that turns largely on the credibility of the employee and the compensation judge’s acceptance of the expert medical opinion of Dr. Prosapio.  Substantial evidence supports the compensation judge’s finding, and we, accordingly, affirm.

The self-insured employer similarly argues that the only evidence supporting the judge’s finding that the employee gave timely notice of the August 2012 injury is the uncorroborated testimony of the employee that he told his supervisor, Jeff Schomel, on the day the injury occurred, that he had injured his leg while moving freight in a trailer.  The employer contends that Mr. Schomel testified that he did not recall the employee telling him that, and Mr. Schomel believed that had he been so informed he would have filled out an injury report.  The employer also argues that the fact that Mr. Schomel admitted he saw the employee limping has no legal significance.  Citing Issacson v. Minnetonka, Inc., 411 N.W.2d 865, 40 W.C.D. 270 (Minn. 1987), the employer asserts that notice that an employee is having some physical difficulties, without being advised the condition is related to work, is not sufficient to provide actual notice of a work injury.

On this issue, as above, the compensation judge accepted the testimony of the employee that he reported an injury to his leg while unloading freight to his supervisor on the day it happened.  He further testified that his supervisor asked him why he was limping the following day and he reminded Mr. Schomel that he had told him about his accident the day before.  Mr. Schomel characterized the employee as honest and an employee in whom he put a lot of trust.  He testified he could not remember the conversation, but had no reason not to believe the employee.

This issue again presents a fact question turning on the credibility of the employee.  The compensation judge did not err in accepting the employee’s testimony, and the compensation judge’s finding is, therefore, affirmed.

The employer asserts the mere fact that the employee is still receiving medical treatment is not dispositive of the question of whether the employee is at MMI, and that a review of Dr. Prosapio’s chart notes disclose that proposed additional treatment consists of conservative measures solely for the purpose of reducing some of the employee’s discomfort.  There is nothing, the employer maintains, in Dr. Prosapio’s records to show he anticipates any significant improvement in the employee’s condition.

Maximum medical improvement is the date after which no further significant recovery from or lasting improvement to a personal injury can reasonably be anticipated.  Minn. Stat. § 176.011, subd. 25.  MMI is an issue of ultimate fact to be determined by the compensation judge.  It is the responsibility of the judge to evaluate the employee’s condition as documented by medical records, medical opinions, and other circumstances.  Factors to be considered include a history of improvement, current treatment, pre-existing conditions, and proposed treatment.  Hammer v. Mark Hagen Plumbing & Heating Co., 435 N.W.2d 525, 41 W.C.D. 634 (Minn. 1989).

At the time of the hearing, the employee was still undergoing treatment with Dr. Prosapio, and was returning to Dr. Prosapio on October 30, 2013, to consider another hyalonic acid injection.  There is at least some evidence that Dr. Prosapio believes the employee may obtain some relief from his pain and improve functioning with treatment, such as cortisone and hyalonic injections, and bracing, and possibly knee replacement in the future.  While we acknowledge a different inference could have been reached, there is sufficient evidence in the record as a whole to support the finding of the compensation judge, and the finding is affirmed.