ROMAN T. KANIEWSKI, Employee, v. WAL-MART STORES, INC., and AMERICAN INT=L GROUP/CLAIMS MANAGEMENT, INC., Employer-Insurer/Appellants, and LAKEVIEW MEMORIAL HOSP., CENTER FOR DIAGNOSTIC IMAGING, MIDWEST SPINE & ORTHOPAEDICS, STILLWATER MEDICAL GROUP, ST. PAUL RADIOLOGY, and HEALTHCARE RECOVERIES, INC., Intervenors.

 

WORKERS= COMPENSATION COURT OF APPEALS

OCTOBER 7, 2002

 

HEADNOTES

 

CAUSATION - DATE OF INJURY.  Where the compensation judge acknowledged that the claimed incident on or about December 27, 1999, was unwitnessed and that there was confusion over the actual date of injury, but where the judge credited the employee=s testimony as to an injury at work about that date and found that testimony corroborated by the medical records, the judge=s finding that the employee sustained a work-related injury to his low back on or about December 27, 1999, was not clearly erroneous and unsupported by substantial evidence, notwithstanding the employer and insurer=s contention that the employee did not even work on December 27, 1999.

 

CAUSATION - AGGRAVATION; CAUSATION - PRE-EXISTING CONDITION.  Where the judge had clearly acknowledged the employee=s pre-existing medical history and the opinions of the independent medical examiner, and where the conclusion of the judge was amply supported by the employee=s testimony and the medical records of the employee=s physician, the compensation judge=s conclusion that the employee=s work injuries with the employer constituted permanent aggravations of the employee=s pre-existing condition was not clearly erroneous and unsupported by substantial evidence.

 

EVIDENCE - ADMISSION.  Where the proposed evidence was not disclosed either in the employer and insurer=s pre-trial statement or at the pre-trial conference held before the judge, and where the employer and insurer had not otherwise established an excuse under Minn. R. 1415.1900, subp. 7, the compensation judge did not abuse his discretion in excluding from evidence certain exhibits not disclosed until the date of the hearing, notwithstanding the employer and insurer=s arguments that they had made a good faith effort to disclose all relevant evidence prior to that time.

 

WAGES - MULTIPLE EMPLOYMENTS.  Where the employer and insurer contended that the employee was no longer working at a second job on the date of his second aggravation injury, where the record did not contain any evidence at all of the employee=s weekly wage on the date of that injury, but where both the employee=s first aggravation injury and his second aggravation injury together had resulted in additional permanent partial disability, the compensation judge=s finding of a weekly wage inclusive of the second job on the date of the second injury was vacated, but the employer and insurer=s appeal from calculation of benefits after the second injury based on a wage equal to the employee=s wage at the time of the first injury was essentially moot, in that the first injury was inferrably a substantial contributing factor in the employee=s condition on the date of the second, and his wage on the date of the first therefore remained applicable in calculating the employee=s compensation on the date of the second.

 

Affirmed in part and vacated in part.

 

Determined by Pederson, J., Rykken, J., and Stofferahn, J.

William R. Johnson.

 

OPINION

 

WILLIAM R. PEDERSON, Judge

 

The employer and insurer appeal from the compensation judge=s finding that the employee sustained permanent aggravations of a pre-existing condition on December 27, 1999, and May 10, 2000, from the judge=s consequent award of benefits, from his determination of the employee=s weekly wage on May 10, 2000, and from his evidentiary rulings excluding exhibits offered by the employer and insurer.  We vacate the judge=s finding as to the employee=s wage on May 10, 2000, and we affirm on all other issues.

 

BACKGROUND

 

Roman T. Kaniewski had a long history of back problems prior to the employment here at issue.  In December of 1991, he experienced low back pain after slipping and falling on some ice in a parking lot.  A CT scan at that time revealed a moderate-sized disc herniation at L5-S1 and mild degenerative bulging at L4-5.  In January of 1995, Mr. Kaniewski sustained a work injury to his back when he fell about fifteen feet from a ladder.  An MRI scan revealed a large disc herniation at L5-S1 and a small disc herniation at L4-5, and in March of 1995 he underwent a laminectomy and discectomy at L5-S1 on the right.  After recovering from his surgery, Mr. Kaniewski returned to work as a maintenance worker, and in February of 1996 he sustained further injury to his low back while moving a refrigerator.  He subsequently had increasing pain, and an MRI scan in April of that year revealed an increase in the size of his L4-5 disc herniation.  About six months later, in October of 1996, Mr. Kaniewski returned to his surgeon with complaints of severe back pain that radiated down his left leg to the knee and down his right leg into the first and second toes.  An MRI scan revealed that the herniation of his L4-5 disc had increased since the April 1996 scan, and in November of 1996 Mr. Kaniewski underwent a right L4-5 laminectomy and discectomy.  Finally, in November of 1996, Mr. Kaniewski experienced renewed back and right-leg radicular symptoms when he slipped and fell on his left buttock and elbow.  A lumbar MRI scan at that time revealed mild disc bulging at L4-5, and Mr. Kaniewski=s doctor recommended an epidural steroid injection to try to relieve the pain.  The injection was administered in December 1996, but symptoms persisted, and in February 1997 a second injection was administered.  Mr. Kaniewski continued thereafter to have low back and leg pain, right greater than left, but he continued to work for nearly three years with no further injuries and little or no treatment for his back.

 

In April of 1999, Mr. Kaniewski [the employee] commenced work with the employer herein, Wal-Mart Stores, Inc. [the employer].  On January 3, 2000, the employee sought treatment with Dr. Charles Hipp regarding an onset of acute low back pain that he alleged had commenced on December 27, 1999, as he was lifting a box of bleach weighing about fifty pounds.  The employee described symptoms of sharp pain in his low back that radiated into his right leg all the way to the calf.  The employee also informed Dr. Hipp about his prior surgeries, and Dr. Hipp reported that, A[s]ince >96, he has done pretty well.  He=s had some off and on low back pain of a mild degree, but no major back symptoms.@  Dr. Hipp took the employee off work at that time.  On that same date, January 3, 2000, the employee completed an AAssociate Statement@ for the employer, describing an injury to the right side of his lower back on December 27, 1999.

 

The employee returned to work on January 10, 2000, when he allegedly immediately reinjured his low back.  He was kneeling down and pulling some cleaners forward on a shelf, and when he tried to stand up he felt a snap and severe low back and leg pain.  He could not stand up or walk without assistance and was taken to Lakeview Hospital, where he was admitted for pain control.  On January 11, 2000, the employee was seen at the hospital by orthopedist Dr. Glenn Buttermann, who ordered a repeat lumbar MRI scan.  The scan reportedly revealed a recurrent disc herniation on the right at L4-5 and disc degeneration at L4-5 and L5-S1.  The employee was discharged from the hospital on January 12, 2000, with plans for the scheduling of an epidural steroid injection as an outpatient.  About eight hours later, the employee was readmitted to the hospital for pain control, and he was discharged the following day.

 

On January 27, 2000, the employee saw Dr. Buttermann in follow-up at Midwest Spine and Orthopaedics.  Dr. Buttermann noted at that time that the L4-5 disc herniation evident on the employee=s January 11 MRI scan encompassed 35% of the spinal canal and impinged upon the right L5 nerve root, and he prescribed an epidural steroid injection.  Subsequent to the injection, the employee returned to Dr. Buttermann=s office for reevaluation of his work ability on February 23, 2000, reporting that he was doing much better and had minimal low back pain and no leg pain.  In a Report of Work Ability dated February 29, 2000, Dr. Buttermann released the employee to return to work on March 6, 2000, with an eighty-pound lifting limitation.  On that same date, Dr. Buttermann referred the employee to NovaCare for a week of physical therapy.

 

On May 10, 2000, the employee again injured his back at work while attempting to slide a heavy box into a customer=s car.  The employee subsequently underwent another epidural injection and was taken off work for three days.  About two months later, on July 18, 2000, the employee returned to Dr. Buttermann=s office with ongoing complaints of low back pain and some right leg pain.  He provided physician=s assistant Lisa Fritz with a history of the flare-up on May 10 and of the consequent epidural injection, followed by another such injection at the end of June.  He was prescribed medication and instructed to return to the clinic as needed.

 

On August 28, 2000, the employee filed a claim petition, seeking temporary total disability and medical benefits as a result of injuries with the employer on December 27, 1999, January 10, 2000, and May 10, 2000.  In his petition, the employee alleged a weekly wage of $489.30.^[1]  The employer and insurer denied primary liability for the claimed injuries, but admitted statutory notice.

 

The employee left his job with the employer on September 19, 2000, having performed his usual work duties since May 13, 2000, without loss of any time from work.  At about this same time, the employee began working for Heartland Realty as a maintenance supervisor for a complex of fifty-one townhomes, where his duties included repairs, handling the turnover of townhouse units, and groundskeeping.  The employee=s leg pain apparently began to increase, and at the beginning of November 2000 he called Dr. Buttermann who recommended a conservative approach, including ice or heat and nonsteroidal anti-inflammatory medication.  The employee=s complaints increased, however, and on December 19, 2000, the employee underwent another epidural steroid injection.  Four days later, he was seen at the Lakeview Hospital Emergency Room with aching pain in his low back and severe radiating right leg pain.  He was given an intramuscular injection of Toradol and sent home on crutches.

 

The employee=s symptoms became progressively intense, and, on January 4, 2001, the employee began missing time from work.  On January 25, 2001, Dr. Buttermann ordered a repeat MRI scan, which was read to reveal a large recurrent disc herniation at L4-5.  Dr. Buttermann reported that the employee had impending cauda equina syndrome, and an urgent laminectomy and revision discectomy was performed on January 26, 2001, which kept the employee off work for about two weeks.

 

On February 2, 2001, the employee was examined by neurosurgeon Dr. Daniel Ahlberg at the request of the employer and insurer.  In a report dated February 2, 2001, Dr. Ahlberg opined that the employee Ahas chronic low back pain syndrome secondary to degenerative lumbar disc and spondolytic disease.@  He did not believe that the employee=s work injuries with the employer had caused any significant exacerbation or permanent change in the employee=s chronic low back pain condition.  He concluded that the employee=s need for further evaluation and surgical treatment in January 2001 Aappears to have resulted from spontaneous progression of his degenerative lumbar disc and spondolytic disease beginning in [November] 2000.@  He attributed the employee=s need for medical treatment and any temporary total disability after January 3, 2000, to the employee=s pre-existing chronic low back pain syndrome.

 

In a report to the employee=s attorney dated November 2, 2001, Dr. Buttermann rendered an opinion in part that 80% of the employee=s condition at the L4-5 level was due to the injury of February 2, 1996, while 20% of that condition was due to the injuries of December 27, 1999, and May 10, 2000, 10% each.  He did not find the injury of January 10, 2000, to be contributory.  In deposition testimony rendered on November 30, 2001, Dr. Ahlberg reiterated his opinion that the employee was subject to chronic low back pain syndrome secondary to degenerative lumbar disc and spondolytic disease.  Dr. Buttermann and Dr. Ahlberg were in agreement over the facts that the employee has a permanent partial disability of 22% to the body as a whole and that medical care and treatment provided to the employee after January 3, 2000, was reasonable and necessary.

 

The employee=s claim came on for hearing before a compensation judge on December 12, 2001.  Issues at hearing^[2] included the following:  (1) whether or not the employee sustained a compensable low back work injury on December 27, 1999; (2) whether or not the employee sustained a compensable low back work injury on May 10, 2000; (3) whether or not the employee was temporarily totally disabled from December 27, 1999, to January 9, 2000, from January 11, 2000, to March 5, 2000, from May 10, 2000, to May 12, 2000, and/or from January 4, 2001, to February 11, 2001; (4) whether or not the employee sustained any permanent partial disability consequent to such injuries, after apportionment to any preexisting condition; and (5) whether medical expenses at issue were causally related to any compensable injuries.  At the hearing, the employee testified in part that about October of 2000 his right leg pain began to grow increasingly severe, until, on November 4, 2000, he awoke with pain so severe that he could not walk.  He denied any new injury at that time and could not identify any activity at Heartland Realty that may have caused the increase in his symptoms.  Also testifying at hearing were four witnesses for the employer, including the employee=s section manager, Troy Buck, who testified that he did not recall the employee reporting the December 1999 injury to him on the date alleged.  In a decision issued February 11, 2002, the compensation judge accepted the employee=s testimony as credible and determined that, while there was confusion about the date of injury, the employee established that he sustained injuries to his low back arising out of and in the course of his employment Aon or about@ December 27, 1999, and on May 10, 2000.  The judge awarded the employee temporary total disability benefits for all but half of the first of the periods claimed.  He also awarded compensation for a 2% whole-body permanent partial disability, based on the employee=s recurrent disc herniation and need for surgery on January 26, 2001, and reimbursement to the employee and intervenors for various medical expenses that had been contested on a causation basis.  The employer and insurer appeal.

 

DECISION

 

The employer and insurer first contend that the compensation judge=s finding of an injury on December 27, 1999, is clearly erroneous and unsupported by substantial evidence, in that evidence is clear the employee did not work on that date.  Moreover, they argue, although even the employee=s written report of injury on January 3, 2000, refers to an injury date of December 27, when confronted with the inconsistencies in his testimony regarding the injury date and his reporting of the injury, the employee changed his testimony and then changed it again.  The employer and insurer argue that the judge erred in concluding that the employee=s testimony was credible.  We are not persuaded.

 

At Finding 3, the compensation judge acknowledged that the claimed incident on or about December 27, 1999, was unwitnessed and that there was confusion over the actual date of injury.  However, the judge credited the employee=s testimony and found that that testimony was corroborated by Dr. Hipp=s medical record for January 3, 2000.  In his memorandum, the judge stated that he had Areviewed the medical evidence and listened to the testimony and found the employee=s story credible.@  The 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), citing Brennan v. Joseph G. Brennan, M.D., 425 N.W.2d 837, 41 W.C.D. 79 (Minn. 1988).  It is not the role of this court to make our own evaluation of credibility or of the probative value of conflicting testimony.  Rather, we must give due weight to the compensation judge=s opportunity to observe the witnesses and to judge their credibility.  Redgate v. Sroga=s Standard Serv., 421 N.W.2d 729, 40 W.C.D. 948 (Minn. 1988).  The judge=s finding that the employee sustained an injury to his low back arising out of and in the course of his employment with the employer on or about December 27, 1999, is amply supported in the record by medical evidence and the employee=s testimony.  Accordingly, we affirm the judge=s finding. 

 

The employer and insurer contend also that the compensation judge failed to address their defense that, even if work injuries did in fact occur on those dates, the employee=s December 1999 and May 2000 injuries were temporary aggravations of a pre-existing condition.  They argue that there is ample and substantial evidence that, after he returned to work for the employer in May 2000, the employee was fully capable of performing the essential duties of his job, including heavy lifting, until he left the employment with the employer in September 2000.  The employer and insurer also note the significant episodes of pain that began for the employee in November 2000, together with Dr. Ahlberg=s opinions that something new and significant occurred at that time, wholly unrelated to anything that occurred at the employer.  We disagree that the compensation judge failed to consider the employer and insurer=s defense.

 

At Finding 3, the judge clearly acknowledged the employee=s pre-existing medical history and the opinions of Dr. Ahlberg.  However, the judge found that the work injuries with the employer constituted aggravations of the employee=s pre-existing condition, and in his memorandum he referred to those aggravations as permanent aggravations.  At Finding 5, the judge awarded an additional 2% permanent partial disability attributed to the employee=s 2001 surgery.  There can be no doubt that the judge rejected the employer and insurer=s temporary aggravation argument.

 

An employee claiming workers= compensation benefits has the burden of proving that a work-related injury caused his disability, but it is not necessary for the employee to show that the work-related injury was the sole cause of his disability, only that the injury was a legal cause--that is, an appreciable or substantial contributing cause.  Salmon v. Wheelbrator Frye, 409 N.W.2d 495, 497-98, 40 W.C.D. 117, 122 (Minn. 1987).  Whether an aggravation of a pre-existing condition is temporary or permanent is a question of fact.  In this case, the judge=s determination that the injuries at issue were permanent aggravations of the employee=s pre-existing condition is amply supported by the employee=s testimony and the medical records, in particular by Dr. Buttermann=s report of November 2, 2001.  While there clearly is substantial evidence in the record to support the employer and insurer=s position, it is not the function of this court to determine whether findings contrary to the judge=s may have been supported by the evidence but whether substantial evidence supports the findings of the judge.  Where evidence is conflicting or more than one inference may reasonably be drawn from it, the findings of the compensation judge are to be upheld.  Redgate, 421 N.W.2d 729, 40 W.C.D. 948.  Accordingly, the judge=s finding of permanent aggravations to the employee=s pre-existing condition on December 27, 1999, and May 10, 2000, is affirmed.

 

The employer and insurer contend also that the compensation judge erred when he prohibited the introduction of certain exhibits at trial on grounds that the evidence had not been identified until the date of trial.  They argue that they made a good faith effort to produce all documents available to them during the course of the litigation but that the documents in question had unfortunately been misplaced and were not discovered until review of other files the day before trial.  We are not persuaded.

 

Minn. R. 1415.1900, subp. 7, provides as follows:

 

Evidence not disclosed at conference.  Evidence, or other matters listed in subpart 5 which have not been disclosed at a settlement or pretrial conference or in a pretrial statement except impeachment or rebuttal witnesses, may not be presented at the hearing unless it is shown to the compensation judge that:

 

A.  the evidence or other matters offered were discovered subsequent to the filing of a pretrial statement or pretrial conference, whichever occurs last;

B.  the evidence or other matters offered were not discoverable through the exercise of due diligence before that time; and

C.  the other parties have been advised of the evidence or other matters before the hearing and have had an opportunity to review them.

 

The employer and insurer have not alleged that the proposed exhibits constituted impeachment evidence, that the proposed exhibits could not have been discovered through the exercise of due diligence prior to the day before trial, or that they advised the employee of the existence of the proposed exhibits prior to the hearing.

 

Generally, a compensation judge has broad discretion regarding the admissibility of evidence in a workers= compensation hearing.  Minn. Stat. ' 176.411, subd. 1; Bey v. Oxford Properties, Inc., 481 N.W.2d 40, 46 W.C.D. 198 (Minn. 1992); Ziehl v. Vreeman Constr. Co., slip op. (W.C.C.A. Oct. 15, 1991) (evidentiary rulings are generally within the sound discretion of the compensation judge).  To warrant reversal, the compensation judge=s ruling on the admissibility of evidence must be prejudicial as well as erroneous.  See McGuire v. Merillat Indus., Inc., slip op. (W.C.C.A. July 27, 1993); see also Elling v. Cub Foods, slip op. (W.C.C.A. Feb. 24, 1994); Brecht v. General Mills, slip op. (W.C.C.A. Jan. 28, 1994).  In this case, where the proposed evidence was not disclosed either in the employer=s pre-trial statement or at the pre-trial conference held before the judge, and where the employer and insurer have not otherwise established an excuse under Minn. R. 1415.1900, subp. 7, the judge=s exclusion of the exhibits in question was not an abuse of discretion.  We see no basis for reversal of the compensation judge=s decision on these facts.

 

Lastly, the employer and insurer contend that the compensation judge erroneously attributed earnings from employment at VFW Post 323 to the employee=s weekly wage at the time of his May 10, 2000, work injury, when the employee was no longer employed at the VFW.  They further argue that the employee conceded that he had worked at another job during the three-day period following that injuryBMay 10 through May 12, 2000--when he claimed to be disabled from work activity at the employer.  We are not persuaded.

 

We agree that the judge=s determination of the employee=s wage on May 10, 2000, is evidently erroneous.  The record does not contain any evidence of the employee=s weekly wage on May 10, 2000, and therefore there is no evidentiary basis for the judge=s finding of any specific weekly wage on that date.  We therefore vacate that portion of Finding 2 that pertains to the employee=s weekly wage on that date.  The judge also found, however, at Finding 5, that both the May 2000 injury and the December 1999 injury resulted in an additional 2% permanent partial disability of the employee=s whole body.  In light of our affirmance of that finding, we conclude that the December 1999 injury was inferrably a substantial contributing factor in the employee=s condition in May 2000 and that the December 1999 wage therefore remains applicable in calculating the employee=s compensation on the date of the later injury.  The employer and insurer=s appeal from the May 10, 2000, wage determination is therefore effectively moot.  As for the contention that the employee worked at another job during the three-day period following his May 10, 2000, injury, during which he claimed to be totally disabled, we have carefully reviewed the record and conclude that the evidence is anything but clear on that issue.  We cannot conclude that the award of compensation for three days of temporary total disability is clearly erroneous or that it was improper for the judge to base that award on a weekly wage equivalent to the employee=s wage as of December 27, 1999.