The employer and insurer appeal from the compensation judge’s determination that the employee has not fully recovered from the effects of his February 13, 2009, work injury; that the employee has not reached maximum medical improvement (MMI); and that the employee is entitled to additional wage loss benefits and medical treatment after November 5, 2009.  We affirm.

Martin Santiago-Clemente, the employee, was born in Mexico and moved to the United States in 1997.  He began working for Alside Supply Center, the employer, in 1998, as a warehouse laborer putting away materials and, later, as a driver delivering materials.  His duties as a driver included loading and unloading boxes, the heaviest of which weighed approximately 90 pounds.  The employee also loaded doors and windows which required the assistance of another person.

The employee was unloading a trailer in the morning of February 13, 2009.  He climbed up on the edge of a pallet to take out a box, crouching down as he reached for the box.  The employee lost his balance and fell forward and down, approximately five to six feet, hitting his left knee and left shoulder.  By the afternoon, his knee was swollen and painful, and he could not raise his arm.  The employee was sent to the Apple Valley Medical Center where he was treated for a soft tissue injury to the left shoulder and left knee, and was provided with crutches and an ace wrap.

On April 5, 2009, the employee began treating with Dr. Robert Hartman at Twin Cities Orthopedics.  The doctor reported that when the employee fell, his arm was abducted and externally rotated, and his knee twisted as he hit the ground.  On examination, Dr. Hartman noted a severely antalgic gait, tenderness in the posterior of the left knee, and some effusion in the joint.  The employee had a posterior drawer sign of 2+, Lachman’s was 1+, and medial and lateral cruciate ligament tests were 1+.^[1]  There was marked anterior swelling in the left shoulder with limited motion, and anterior and inferior instability.  The doctor diagnosed a probable transient dislocation with instability in the left shoulder, and a grade II posterior cruciate ligament (PCL) sprain^[2] in the left knee.  Dr. Hartman ordered MRI scans of the left knee and left shoulder and took the employee off work.

The March 9, 2009, left shoulder MRI scan revealed broad-based, complex tearing of the superior portion of the glenoid labrum, subscapularis tendinopathy with superficial and deep surface fraying, and supraspinatus tendinopathy with a superficial surface partial-thickness tear.  The left knee MRI scan showed evidence of a moderate to severe broad-based PCL sprain with at least partial-thickness tearing of the mid portion.  There was no evidence for meniscal tearing and the ACL appeared intact without evidence for sprain or rupture.

The employee returned to Dr. Hartman on March 12, 2009.  The doctor recommended an arthroscopic labral repair of the shoulder.  Options for treatment of the knee were also discussed, including physical therapy and a knee brace.  An arthroscopic SLAP (superior labral anterior-posterior) lesion repair of the left shoulder was performed on March 25, 2009.  During the surgery, it was noted that the labrum was extensively deformed, shredded and torn anteriorly.

At the employee’s May 20, 2009, follow-up visit, Dr. Hartman noted the shoulder was progressing well, although there was some mild grinding in the shoulder.  The employee’s primary complaint at the time was constant pain and abnormal movement in the left knee.  On examination, Dr. Hartman noted at least a grade II and possibly a grade III posterior drawer, and stated that, clinically, it felt like a complete rupture of the PCL.  The doctor referred the employee to Dr. James Schaffhausen at Twin Cities Orthopedics for further evaluation and treatment of the knee.

The employee was seen by Dr. Schaffhausen on June 4, 2009.  On examination of the left knee there was quad atrophy, some mild crepitation with active range of motion, grade I Lachman’s anteriorly and grade II posteriorly.  The doctor recommended a course of physical therapy followed by work hardening, stating, “I would favor non-surgical management for as long as possible.”^[3]

The employee returned to Dr. Hartman on June 17, 2009, for follow-up of his shoulder.  The employee reported feeling quite good with only occasional aching anteriorly.  There was full range of motion in the shoulder, except external rotation which was limited by approximately ten degrees.  The doctor observed the employee would “need at least a year to a year and one-half following his index operation to achieve normal strength.” ^[4]

On July 20, 2009, the employee was seen by Dr. Schaffhausen.  The employee reported the physical therapy helped a little bit.  The left quad still demonstrated atrophy with grade II posterior Lachman’s in the knee.  The doctor referred the employee for a 6 week course of work hardening.

On July 30, 2009, the employee was seen by Dr. Hartman for a final recheck of the left shoulder.  The employee continued to have a ten-degree loss of motion in external rotation but had no other complaints.  Dr. Hartman indicated the shoulder had “fully recovered” and released the employee to return to normal activities without restrictions or limitations.^[5]  The doctor stated it was reasonable for the employee to return to work so long as he wore a PCL brace for his knee full-time.

By letter dated August 24, 2009, the employer notified the employee that “pursuant to Section 10(d) of the Labor Agreement since you have been unable to work for more than six months . . . your employment is terminated.”  A second letter dated August 31, 2009, stated that “[a]ll employee health benefits terminate on August 25, 2009.”^[6]

A Health Care Provider Report was completed by Dr. Hartman on September 9, 2009, stating the employee had reached MMI for the left shoulder as of July 30, 2009, with a 0% permanent partial disability based on Minn. R. 5223.0450, subp. 4.A.(1).

In a follow-up visit with Dr. Schaffhausen on September 29, 2009, the employee stated his knee was doing “so-so.”^[7]  He was progressing with work hardening, but was not completely better.  Range of motion in the knee was normal, but the employee continued to have a grade 1+ to 2+ posterior Lachman’s.  The employee stated he would like to return to work, and Dr. Schaffhausen ordered a functional capacities evaluation (FCE).

An approximately three-hour FCE was completed on October 20, 2009.  The employee testified the testing hurt his shoulder and knee, but he kept on because he wanted to get back to work.  The FCE summary report stated the employee was “currently functionally capable of meeting the demand of the position of a Driver (Laborer) for Alside Supply Center as described in the employer’s/client’s description of the job.”^[8]  The testing indicated the employee could lift up to 100 pounds occasionally, 70 pounds frequently; carry up to 100 pounds occasionally, 65 pounds frequently; stand, walk, climb stairs, and stoop frequently; and kneel, crouch, or crawl occasionally.

On November 3, 2009, Dr. Schaffhausen stated that “[b]asically [the employee] can perform his job duties.  At this point we will let him return to work this coming Friday without any significant restriction.”^[9]  The employee was last seen by Dr. Schaffhausen on November 18, 2009.  On examination, his posterior Lachman’s was grade II, posterior drawer was grade III.  The doctor’s diagnosis was PCL decay of the left knee.  The employee was to continue with his strengthening exercises and follow-up for further care as necessary.  The doctor completed a Health Care Provider Report stating the employee had reached MMI as of November 3, 2009, and provided a permanent partial disability rating of 5% pursuant to Minn. R. 5223.0510, subp. 3.D.(2).^[10]  The employer and insurer discontinued payment of workers’ compensation benefits as of December 10, 2009.

On May 3, 2010, the employee sought treatment from Dr. Douglas Butler at Minneapolis Orthopaedics.  The employee testified he did not return to Dr. Schaffhausen because it was his understanding that workers’ compensation would not pay additional benefits, and Dr. Becker was willing to see him even though he did not have insurance.  The employee’s primary complaint was persistent left knee pain, weakness, and buckling.  On examination, the employee limped on the left side and he had a 1+ to 2+ posterior drawer with trace effusion in the joint.  The doctor diagnosed a left knee PCL sprain, provided the employee with a brace, gave him home exercises, and provided restrictions limiting standing and walking to 3 hours a work day, with no stooping, squatting, kneeling, or stair climbing.

The employee was seen by Dr. Alfonso Morales on August 13, 2010, complaining of left knee and left shoulder pain as the result of his February 13, 2009, work injury.  On examination there was pain throughout the knee.  The employee was wearing a hinged brace and was advised to continue to use it.  He was referred for physical therapy and was prescribed Meloxicam, a non-steroid anti-inflammatory with an analgesic.  On August 27, 2010, the employee was additionally prescribed Pennsaid, a topical analgesic.  In follow-up on October 4, 2010, Dr. Morales noted the employee continued to have tenderness and crepitation in the knee.  The employee was advised to continue his range-of-motion and strengthening exercises and to return as necessary.  Dr. Morales opined the employee’s condition was permanent, and that he might need injections, further physical therapy, and possibly surgery in the future due to further degeneration of the knee.  The employee testified he did not follow-up with Dr. Morales after that time due to his inability to pay and lack of insurance.

After the employee was terminated from his job with the employer, he sought light-duty work through temporary agencies.  In January 2011, the employee started working two jobs at a wage loss:  30 to 38 hours a week at Aveda, through Masterson Personnel, packaging lotions and shampoos, and approximately 30 hours a week driving a van delivering Los Maizeles tortillas for Marissa’s, a grocery store.

The employee was contacted on September 7, 2011, by a qualified rehabilitation consultant (QRC) for an evaluation for rehabilitation assistance.  The QRC noted the employee continued to have problems with his left knee and left shoulder and that the employee believed he needed medical attention and work restrictions.  The QRC contacted Dr. Becker’s office and an MRI scan of the left knee was ordered.

The employee saw Dr. Becker on September 21, 2011, for his left knee and his left shoulder.  The employee reported pain in his knee with difficulty standing, walking, squatting, kneeling, and stairs.  The September 20, 2011, MRI scan of the left knee showed evidence of healing of the PCL tear, a chronic sprain of the ACL, and fraying in the posterior third of the medial meniscus.  The left shoulder had audible and palpable subacromial crepitus with cuff tenderness and a positive impingement sign.  Dr. Becker’s impression was left knee resolving PCL sprain with ACL sprain and left shoulder impingement syndrome.  Dr. Becker injected the employee’s left knee and advised the employee to continue with his exercise program.  The doctor stated the employee might need additional physical therapy, and if there were ongoing difficulties, an arthroscopic examination might need to be considered.

The employee returned to Dr. Becker on November 9, 2011.  He reported the left knee was more symptomatic than the shoulder with persistent pain and weakness, although he stated the injection helped.  An MRI scan of the left shoulder on October 18, 2011, showed evidence of interstitial tearing of the supraspinatus at its insertion point and some acromioclavicular joint degeneration.  The doctor diagnosed a partial tear in the PCL of the left knee, slightly improved, with interstitial tearing and impingement syndrome in the left shoulder.  Dr. Becker imposed restrictions of no lifting over 10 pounds with the left arm and continued restrictions for the left knee.  In follow-up on December 21, 2011, the employee stated his knee was painful and sometimes felt like it was going to buckle.  He reported he continued to have difficulty with overhead use of the shoulder with pain.  The employee expressed frustration with his lack of improvement, and declined additional treatment other than conservative care.

When seen on January 11, 2012, the employee stated his primary problem was weakness/instability and pain in the knee.  Treatment options were discussed and the employee expressed a desire to pursue surgical treatment.  Dr. Becker recommended a left knee arthroscopic evaluation with probable ACL and PCL repair and partial medial and lateral meniscal debridement.

The employee was examined on August 7, 2012, by Dr. Mark Engasser, an orthopedist, at the request of the employer and insurer.  The employee reported left knee pain and a feeling of looseness in the knee.  On examination, the employee had a 2+ posterior drawer sign.  He stated he had problems walking and going up stairs, kneeling, and extensive bending.  The employee reported left shoulder tightness with periodic flare-ups of shoulder pain.  On examination there was anterior shoulder pain at the extremes of motion, and discomfort with abduction and external rotation.  He stated he tried to avoid heavy lifting and extensive overhead reaching and rotation.  Dr. Engasser’s diagnosis was left knee grade II PCL strain and left anterior shoulder instability with labral tear post SLAP repair.  Dr. Engasser opined that the February 13, 2009, injury did not substantially contribute to the employee’s present condition.  The doctor maintained no additional treatment was needed for either the shoulder or the knee, and he did not feel the employee exhibited sufficient clinical instability in the knee to justify a PCL repair.  Dr. Engasser opined that the employee had reached MMI with respect to the shoulder and the knee by November 2009, and that the employee could work without restrictions or limitations.

By report dated September 19, 2012, Dr. Becker stated the employee continued to have symptoms due to impingement syndrome in the left shoulder, and a resolving PCL sprain with an ACL sprain and a possible small medial meniscus tear in the left knee.  Dr. Becker maintained the employee’s present left shoulder and left knee conditions are the result of the employee’s February 13, 2009, work injury.  In Dr. Becker’s opinion, the employee’s medical treatment was reasonable and necessary and causally related to his work injury.  Dr. Becker stated the employee had continuing restrictions of no lifting over ten pounds for the left shoulder, and, for the left knee, no stooping, squatting, kneeling, or stair climbing and a maximum of three hours of standing and walking per eight-hour work day.  The doctor opined the employee was not at MMI and needed additional treatment, likely including left knee arthroscopic surgery and revision left shoulder arthroscopic surgery as a result of the work injury.

Following a hearing at the Office of Administrative Hearings on October 10, 2012, a compensation judge found the employee had not fully recovered from the effects of his work injury of February 13, 2009; that he had not reached MMI; that the arthroscopic surgery, including a PCL repair, recommended by Dr. Becker was reasonable, necessary, and causally related to the work injury; that the employee was entitled to payment of his outstanding medical expenses; and that the employee was entitled to additional wage loss benefits, including temporary total benefits and temporary partial disability benefits from and after November 5, 2009.  The employer and insurer 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.^[11]  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.^[12]  Fact findings are clearly erroneous if the reviewing court, looking at the entire evidence, is left with a definite and firm conviction that a mistake has been committed.^[13]  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.”^[14]

The employer and insurer argue that by November 2009, the employee had fully recovered from the effects of his February 13, 2009, injury and had no work-related disability.  They assert that both Dr. Hartman and Dr. Schaffhausen released the employee to return to work without restrictions, and that the October 2009 FCE determined the employee was capable of meeting the demands of the position of a driver/laborer for Alside Supply Center.

The employer and insurer assert the judge’s primary basis for the award of additional benefits was her conclusion that the employee’s testimony was credible.  They argue, however, that in the face of the medical evidence as it existed in November 2009, the compensation judge could not have found the employee credible.  As a general rule, an employee’s testimony alone may constitute sufficient evidence to support a compensation judge’s finding that the employee has a disability that restricts or limits his ability to perform work.^[15]  The question of whether the employee has any residual disability and is able to return to work without restrictions is one of fact for the compensation judge to determine.^[16]

The employee testified that on July 30, 2009, when Dr. Hartman stated he could return to work, his shoulder still hurt and he did not believe he could work without limitations.  The employee further testified that following the FCE the knee was not back to 100% and he did not feel he could work without any restrictions.  The employee stated he currently has pain in the left shoulder and it clicks and pops when he tries to lift it up.  He stated the left knee feels like it is going to give out or buckle and is unstable.

The employee has had persistent findings of a grade II or grade III posterior drawer or posterior Lachman’s test in the left knee, and has consistently reported pain and a feeling of buckling or weakness in the knee.  He has a ratable 5% permanent partial disability for cruciate laxity, posterior, in the left knee.  He has also complained of persistent pain and constricted movement in the shoulder.  The employee testified that his job at Alside required frequent crouching, kneeling and stooping, and the October 2009 FCE indicated the employee’s ability to kneel, crouch, and crawl was limited.  Dr. Beckman stated the employee continued to have symptoms of a PCL sprain with an ACL sprain in the left knee and imposed work restrictions for the left knee that included no stooping, squatting, kneeling or stair climbing and a maximum of three hours of standing and walking per 8-hour work day.  The compensation judge found credible the employee’s testimony that he continued to experience symptoms in his shoulder and knee and that he continued to have a disability that affected his ability to work.  Assessment of a witness’s credibility is the unique function of the trier of fact, and in reviewing cases on appeal, this court must give due weight to the opportunity of the compensation judge to judge the credibility of witnesses.^[17]  In this case, the record adequately supports the compensation judge’s credibility assessment.

The employer and insurer argue the employee’s testimony lacks credibility and has little probative value because he did not return to his job with the employer and therefore did not have first-hand knowledge of whether he was actually capable of doing the job.  The employee missed nine months of work and was terminated by the employer in August 2009, after missing six months of work, and before the FCE was completed in October.  Since the job was clearly no longer available to the employee in November 2009, the employee’s “actual” ability to do that job has little evidentiary value for the purposes of weighing the employee’s credibility.  The issue is not whether the employee could have returned to his pre-injury position with the employer, a job that was not available to him.  The question is whether the employee has a disability as a result of his work injury that affects his current ability to find and hold a suitable job.

The compensation judge found the opinions of Dr. Becker persuasive and consistent with the employee’s testimony in determining that the employee had not fully recovered from the effects of his February 13, 2009, injury and had continuing symptoms and restrictions on his activities as a result of the injury to his left knee and left shoulder.  The employer and insurer argue that Dr. Becker’s opinion is an “anomaly” that should not have been favored over the opinions of the physicians who treated his left knee and left shoulder in 2009, and the opinion of Dr. Engasser, which, they assert, is consistent with the opinions of Dr. Hartman and Dr. Schaffhausen.

Dr. Becker began treating the employee in May 2010, less than six months after the employee’s last visit with Dr. Schaffhausen.  At that last visit, Dr. Schaffhausen recorded a grade II posterior Lachman’s sign and a grade III posterior drawer sign, and diagnosed PCL decay of the left knee.  Dr. Becker treated the employee periodically from 2010 through 2012.  He took a history, examined the employee, reviewed his medical records, and performed various diagnostic tests.  He diagnosed PCL and ACL sprains in the left knee along with left shoulder impingement syndrome based on the results of his examinations and testing, and imposed work restrictions based on his findings and the employee’s complaints.  Dr. Engasser also noted a positive 2+ posterior drawer in the left knee and pain with abduction and external rotation of the left shoulder on examination.  He disagreed, however, with Dr. Becker’s opinion that these findings were causally related to the February 13, 2009, work injury, and believed the employee was capable of working without limitation or restriction.

It is the function of the compensation judge to resolve conflicts in expert medical testimony, and his or her choice of expert opinion is to be upheld so long as the accepted medical opinion has adequate foundation.^[18]  The employer and insurer do not contend that Dr. Becker’s opinion lacks foundation, only that the overwhelming weight of the medical evidence requires rejection of Dr. Becker’s opinion.  The “weight of evidence” refers to the believability or persuasiveness of the evidence.  The probative value of evidence, that is, the tendency to convince a person of the truth of a proposition, does not necessarily turn on the number of witnesses, but rather the persuasiveness of the witness’s testimony.  It is not the function of this court on appeal to reevaluate the probative value of the evidence.^[19]  Rather, this court’s function on appeal is solely to determine whether the findings and conclusions reached by the compensation judge are supported by substantial evidence in the record as a whole.^[20]

The medical experts in this case came to opposing conclusions on the issue of causation, the need for restrictions, and the need for ongoing medical treatment.  The judge found the conclusions and opinions of Dr. Becker more persuasive.  Having carefully reviewed the record, we conclude the evidence as a whole is adequate to support the decision of the compensation judge, and we affirm.