The employee appeals from the judge’s findings regarding the nature of the work injury, the date that the injury resolved, maximum medical improvement, and the discontinuance of benefits.  We affirm.^[1]

The employee sustained a work-related injury to his right hip on October 28, 2010, when turning/twisting while lifting 4 by 4s at work as a shipping supervisor for Ratner Steel Supply Company [the employer].  At that time, he felt a popping and pain in that hip.  He first treated for that injury with Dr. Walid Mikhail on November 2, 2010.  Dr. Mikhail recorded that the employee had been experiencing right hip pain for six months but had never had a “popping” before the previous week.  X-rays taken on that date showed some joint space narrowing of the hip.  Dr. Mikhail recommended restrictions that included no lifting more than 10 pounds, and the employee continued in his job as a shipping supervisor until January 24, 2011.

An MRI performed on December 2, 2010, showed mild degenerative arthritis of the hips bilaterally, without effusions.  There was probable degenerative tearing of the posterior superior labrum in the right hip and a right-sided peritrochanteric edema-like signal associated with distal gluteal tendons that was consistent with either tendon strain or peritrochanteric inflammation.

The employee was referred to orthopedist Dr. Jack Bert, who on December 8, 2010, recorded that the employee had been experiencing pain in the lateral aspect of the right hip.  On examination he found a slight clicking sensation with flexion and internal rotation and diagnosed a right hip labral tear with greater trochanteric bursitis.  He administered a steroid injection into the right greater trochanteric bursa.  On return to Dr. Bert’s office on February 4, 2011, the employee was seen by Physician Assistant Karl Dennis, who noted that the employee was doing well following the injection.  On exam, there was no audible or palpable pop or click, and the employee was nontender at the greater trochanter.  While the employee continued to complain of groin pain, Mr. Dennis stated, “he [is] done with the trochanteric complaint.”  The employee was referred to Dr. Chris Larson for consideration of an arthroscopy for the labral tear.

Dr. Larson saw the employee on March 10, 2011, at which time the employee was complaining of deep lateral pain in the right hip.  Dr. Larson explained to the employee that his labrum was not the likely cause of the irritability in his hip.  He referred the employee for physical therapy and opined that, if the employee’s symptoms did not improve in the next few weeks, he would consider administering a right-sided hip intraarticular cortisone injection.

The employee continued to experience hip pain and underwent physical therapy and corticosteroid injections.  He treated with Dr. Mikhail, Dr. Larson, and Dr. Daniel Hoeffel at Summit Orthopedics, the latter of whom diagnosed hip dysplasia and labral tearing “related to the workers comp injury in 2010.”  In August 2011, Dr. Larson opined that the employee was not a candidate for arthroscopy since much of his pain appeared to be extraarticular in nature.

On September 26, 2011, the employee was seen by Dr. Jeffrey Geddes at the emergency room of United Hospital, complaining of severe right hip pain that had begun 10 days earlier.  At that time, he described his pain as out of control.

An MRI performed on October 15, 2011, showed ongoing reactive changes of marked arthropathy/osteoarthritis of the right hip joint, including a large hip joint effusion and marked synovitis.  The MRI report noted the possibility of infection and septic arthritis.  X-rays on November 7, 2011, showed bone-on-bone end-stage cartilage loss in the right hip.

Dr. Hoeffel recommended a hip replacement and issued a report on February 2, 2012, wherein he opined that the employee’s right hip pain was the result of a permanent aggravation of a preexisting mildly arthritic condition, which had gone on to a rapid acceleration and worsening as a result of the 2010 work injury.  He further stated that it was the arthritic changes within the employee’s hip that were driving the employee’s symptoms and treatment.

Dr. Gary Wyard examined the employee on behalf of the self-insured employer on September 1, 2011, and February 16, 2012.  In his report of February 17, 2012, he wrote that the employee had a progressive inflammatory process of the right hip, “etiology undetermined but nontraumatic in nature.”  It was further his opinion that “the x-rays and MRIs [did] not show significant findings of osteoarthritis but rather arthropathy and inflammatory reactive bone edema in the acetabulum.”  While he agreed that the employee would be a candidate for a hip replacement, after laboratory work and a possible aspiration was performed to determine the cause of the inflammatory process, he did not find the proposed surgery to be causally related to the work injury.

Dr. Hoeffel issued a second report on March 2, 2012, after he had reviewed the February 17, 2012, report of Dr. Wyard.  He noted that the laboratory work-up had been completed and that the results were all normal, which reinforced his opinion that “the incidents and events as noted in my original report while under the employment of Ratner Steel Supply contributed substantially to his current hip condition on the right.”

Dr. Wyard testified by deposition on February 23, 2012, that the employee’s work injury would have caused, at most, a temporary sprain/strain superimposed on a preexisting mildly arthritic hip, which would have resolved within one to three months.  He testified that the labral tear was not the cause of the employee’s symptoms and that hip dysplasia was a congenital condition.  It was his opinion that the employee’s pain was coming from the infection in his hip, but he agreed that the employee had bone-on-bone end-stage cartilage loss in the right hip.

A hearing was held before Compensation Judge Jeanne Knight on the employer’s petition to discontinue benefits and the employee’s claim petition for underpayment of temporary total disability benefits, unpaid temporary partial disability benefits, unpaid permanent partial disability benefits, and approval of a total hip replacement.^[2]

Judge Knight found, in part, that the employee had sustained a specific injury to his right hip on October 28, 2010, that the employee’s right hip injury had resolved by March 10, 2011, that the employee required a right total hip replacement due to cartilage loss, and that the cartilage loss did not arise out of or in the course of the employee’s employment and was not related to “the right hip labral tear or trochanteric bursitis.”  She also found that the employee did not sustain a Gillette injury.  The employee appealed to this court.

In our decision dated April 9, 2013, we reversed and remanded the matter for additional findings as to the specific nature of the October 28, 2010, work injury, whether the employee had reached maximum medical improvement from the effects of that injury, and whether the work injury, as determined by the judge, had resolved and, if so, when.

The case went back to the Office of Administrative Hearings and was assigned to Judge Stacy Bouman.^[3]  She asked each party to submit written briefs addressing the issues on remand, held a hearing where the parties argued their positions, reviewed the exhibits and evidence from the first hearing, and then issued Findings and Order on Remand.  She found that the nature of the injury was a right hip sprain/strain with a popping or clicking in the hip, that the work injury resolved by February 4, 2011, that maximum medical improvement was reached by February 4, 2011, and that the self-insured employer was entitled to a credit for temporary total disability benefits paid after February 4, 2011.  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 (2014).  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 employee first contends that the compensation judge erred in finding that the employee lacked credibility, arguing that the employee “is the only one who, most authentically, can document the significance of the accident and the progressive nature of its effects.”  What the compensation judge actually found was that the employee testified that the medical records would provide more accurate information regarding his medical condition than his testimony at hearing.  In addition, the judge noted in her memorandum that the employee’s testimony contradicted medical records and was “admittedly, unreliable.”  This conclusion is supported by the employee’s repeated assertions at hearing that he was “groggy,” his repeated answers of “I don’t recall,” or “I can’t recall,” during cross examination, and his agreement that his medical records would be the best source of information as to his medical condition.  Assessment of a witness’s credibility is the unique function of the trier of fact.  Even v. Kraft, Inc., 445 N.W.2d 831, 42 W.C.D. 220 (Minn. 1989).

The employee next contends that substantial evidence does not support Judge Bouman’s finding that the work injury was a right hip sprain/strain with popping or clicking.  We are not persuaded.

Five days after the work injury, Dr. Mikhail recorded that the employee had experienced a six-month history of hip pain with a popping in the hip in the previous week.  Dr. Bert noted a clicking sensation in the right hip at the time he examined the employee in December of 2010.  The MRI performed days later had findings consistent with a tendon strain.  Dr. Wyard testified that the employee had sustained, at most, a sprain or strain at the time of the injury.  These medical records and opinions provide substantial evidence to support Judge Bouman’s finding of a right hip sprain/strain with popping or clicking, and we affirm.

Judge Bouman noted in her memorandum that she found the testimony of Dr. Wyard to be the most persuasive.  The employee alleges that Dr. Wyard erroneously assumed that, after the work injury, the employee performed his pre-injury job without problems.  However, Dr. Wyard’s deposition reflects that the doctor was aware that the employee worked “with restrictions” for the three months after his injury.  The employee further alleges that Dr. Wyard assumed that Dr. Mikhail had eased the employee’s work restriction to 40 pounds lifting on January 27, 2011.  This change of restrictions appears in Dr. Mikhail’s records, and there is no evidence, other than the employee’s testimony, that the change was made solely because the employee requested it.  In addition, the record indicates that Dr. Wyard examined the employee, reviewed his medical records, reviewed the actual MRI scans and x-rays, and had the history of the injury as reported by the employee on exam and as given by hypothetical.  As an orthopedic surgeon who sees patients and performs surgeries, Dr. Wyard clearly had foundation to render his opinions.

A judge’s choice of expert opinions is generally upheld unless the facts assumed by the expert in rendering his opinion are not supported by the evidence.  Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985).  The compensation judge accepted the opinions of Dr. Wyard over those of the other doctors, and we find no basis to conclude that the judge erred in this regard.

Judge Bouman found that the work-related sprain/strain with clicking and popping had resolved by February 4, 2011.  The employee contends that the judge erred in that finding based on a pain questionnaire that the employee completed on that date and the subsequent records of Dr. Larson and Dr. Hoeffel.  We are not convinced.

After Dr. Bert’s finding of a slight “clicking” sensation on exam and tenderness over the greater trochanter, Mr. Dennis, on February 4, 2011, noted that there was no “click” or “pop” and no tenderness over the greater trochanter.  Mr. Dennis found that the employee “[is] done with the trochanteric complaint.”  Admittedly the employee completed a pain questionnaire on that date indicating his pain was at an 8.  Mr. Dennis, however, was aware of the questionnaire as evidenced by his signature on the form, and his office note specifically stated that “groin pain” was persisting.  In addition, Dr. Wyard specifically testified that the mild sprain/strain “would have resolved within a month to three months after the injury.”

Medical records indicate that Dr. Larson was consulted to determine whether the employee would benefit from arthroscopy for treatment of his degenerative labral tear, a condition which Dr. Wyard opined was not related to the work injury and which most doctors eventually agreed was not causing the employee’s complaints.  Dr. Hoeffel’s subsequent records do show ongoing hip symptoms after February 4, 2011.  However, those ongoing symptoms are consistent with Dr. Wyard’s opinion that the employee experienced rapid chondral loss sometime after the December 2010 MRI.  And, again, Dr. Wyard opined that the chondral loss and inflammatory process were not related to the work injury.

This is a medically complicated case.  Doctors have rendered a variety of diagnoses, and opinions as to causation differ.  The compensation judge explained in her memorandum that the employee had preexisting personal conditions, “which include congenital hip dysplasia, bilateral degenerative arthritis, a paralabral cyst and a degenerative labral tear.”  Dr. Wyard’s opinions support this conclusion.  The judge’s finding that the work injury resulted in a temporary aggravation of the preexisting conditions in the nature of a right hip sprain/strain with popping and clicking is supported by substantial evidence, as is her finding that the sprain/strain resolved by February 4, 2011.

Judge Bouman found that the employee reached maximum medical improvement [MMI] on February 4, 2011.  MMI is defined as “the date after which no further significant recovery from or significant lasting improvement to a personal injury can reasonably be anticipated, based upon reasonable medical probability, irrespective and regardless of subjective complaints of pain.”  Minn. Stat. § 176.011, subd. 13a.  We have affirmed the judge’s finding that the employee’s work injury was temporary and resolved by February 4, 2011.  The judge’s MMI finding is therefore affirmed as well.

The employee contends that certain findings of Judge Knight were appealed from but not addressed in this court’s April 9, 2013, decision.  Specifically, he contends that he appealed the judge’s finding that the employee did not sustain a Gillette injury to his right hip.^[4]  The employee’s only argument on this issue is found in his appellant’s brief filed in the appeal of Judge Knight’s decision, wherein he contended, “there is an argument to be made that this Trial Court incorrectly denied the occurrence of a Gillette type injury from the work activities before October 28, 2010 and post that date to January 24, 2011.”  In his Appellant’s Reply Brief, the employee pointed to Dr. Mikhail’s records as supporting a Gillette injury claim.  It is questionable whether the issue was raised sufficiently to warrant discussion by this court.  However, we would note that Dr. Wyard opined that there was nothing in the nature of the employee’s job to cause a Gillette injury.  Dr. Wyard’s opinion provides substantial evidence to support Judge Knight’s denial of the employee’s Gillette injury claim.

The employee also contends that Judge Knight did not address his entitlement to additional vocational rehabilitation assistance, a fact that he noted on his appeal to this court back in 2012.  However, Judge Bouman’s decision that the effects of the work injury ended as of February 4, 2011, resolves claims for all workers’ compensation benefits after that date.