The employer and insurer appeal from the compensation judge's award of temporary total disability benefits, from the judge’s calculation of temporary partial disability benefits, and from the judge’s award of payment for proposed right thumb surgery.  We affirm.

On September 22, 2003, Henry Magarin sustained for the first time an injury to his right thumb, when he struck it against a metal materials basket in the course of his work as a roofer of mobile homes with Highland Manufacturing.  Mr. Magarin [the employee] was thirty-one years old on that date and was earning a weekly wage of $476.03.^[1]  Highland Manufacturing [the employer] admitted liability for the injury, and on September 25, 2003, the employee was seen by Dr. Sundara Nalla, who observed that the metacarpophalangeal [MP] joint in the thumb was swollen and tender.  X-rays proved negative, and Dr. Nalla diagnosed a contused/strained right thumb, prescribed a thumb splint and antiinflammatories, and restricted the employee from using his right hand - a restriction that was evidently not honored by the employer until the doctor personally called the supervisor on October 1, 2003.  The MP joint remained swollen and painful, and on October 8, 2003, Dr. Nalla observed an apparent significant laxity of the lateral ligament on the radial aspect of the employee’s right thumb.  He diagnosed a probable torn lateral ligament on the radial aspect of the MP joint and referred the employee for a consultation with orthopedic osteopath Dr. Lawrence Donovan.  Upon examination of the employee on October 17, 2003, Dr. Donovan observed no swelling or effusion in the thumb, but he did note that the MP joint did appear notably prominent.  He diagnosed contusion, prescribed a splint, referred the employee to occupational therapy, and restricted him to light duty work with no heavy or repetitive grasping.

Over the course of the next few months, Dr. Donovan continued to treat the employee without much evident effect on the stability or level of pain in the employee’s thumb.  Eventually, on February 9, 2004, he administered a cortisone injection in an attempt to relieve increasing pain over the area of the ulnar collateral ligament [UCL] and MP joint.  Two weeks later, on February 23, 2004, the employee elected to proceed with surgical repair or reconstruction of what Dr. Donovan perceived to be a torn UCL in the injured right thumb.  On March 17, 2004, Dr. Donovan performed an arthrotomy of the employee’s injured MP joint, but according to his operative findings he found in the course of his surgery that “[t]he ulna[r] collateral ligament appeared to be intact” and “[t]he thumb appeared to be stable,” although there did appear to be “an area of possible early posttraumatic arthritis.”  Upon completion of the arthrotomy, Dr. Donovan prescribed a short arm thumb cast for about three weeks and eventually occupational therapy.  Initial occupational therapy [OT] records on April 12, 2004, which erroneously imply that the UCL was repaired in the course of the March 17, 2004, surgery, indicate that by that date healing appeared to be proceeding well.  The employee was released to return to work at light duty on March 29, 2004.  OT records for April 29, 2004, a month later, indicate that the employee was rating his pain by that time at a level 4 on a scale of 1 to 10.  Records for May 4, 2004, indicate that the employee “did not feel his thumb was getting better” and was having “shooting pain when he uses his lateral pinch.”  On May 7, 2004, Dr. Donovan kept the employee on restricted duty work but indicated that he could “use hand as tolerated.”  OT records upon the employee’s discharge from therapy on May 26, 2004, report that, after a total of eight sessions, from April 12 to May 4, 2004, the employee had completed five of five original therapy goals.

On June 8, 2004, the employee was working with coworker John Menting on the roof of one of the homes under construction by the employer, apparently doing essentially the same work as he had been performing on the date of his work injury, for the same weekly wage.  On that date, neither the employee nor Mr. Menting had hooked up his OSHA-mandated safety harness when their supervisor, Timothy Heronimus, first came by to observe their work and ordered them to hook up their harnesses.  When Mr. Heronimus came by again about fifteen minutes later, Mr. Menting had hooked up his harness but the employee had not.  Mr. Heronimus ordered the employee either to do so or to go home, upon which order the employee, for reasons that remain at issue, declined to do so, came down off the roof of the home that he was working on, and left the employer’s premises, returning thereafter only once, to pick up a paycheck.

On June 11, 2004, about three days after being sent home from his job with the employer and about three months after his March 2004 surgery, the employee followed up with Dr. Donovan again, who noted in his treatment records that the employee “was doing relatively well until he injured his thumb recently at work.”  Although he found “no swelling, abrasion or bruising” at the site of the surgery, Dr. Donovan did find that the employee had “limited active flexion of the thumb IP joint,” that “[h]e complains of some mild pain along the ulnar side of the thumb metacarpal head,” and that there was some “[s]light prominence of the thumb CMC joint but [it was] not significantly tender.”  Under a diagnosis of “[h]istory of contusion,” “[p]ost-traumatic arthritis,” and “[s]tatus post arthrotomy,”^[2] Dr. Donovan fitted the employee with a thumb splint and gave him permission to “use his hand as tolerated.”

On July 8, 2004, the employee evidently aggravated his right thumb condition in a parenting incident at home, and he went to Dr. Nalla for a prescription of pain medication, which was issued.  The following day, July 9, 2004, he saw Dr. Donovan again, regarding some left ankle and knee pain in addition to “some mild discomfort and stiffness” in his right thumb MP joint.  Dr. Donovan found the MP joint stable, however, and the thumb incision well healed, with “no significant swelling, bruising, or abrasion.”  Under those findings, and, under a diagnosis of history of gamekeepers thumb, status post arthrotomy in the MP joint, and probable early posttraumatic arthritis, Dr. Donovan concluded that the employee was at maximum medical improvement [MMI] with regard to his right thumb injury, concluding further that “no further active medi[c]al or surgical care is indicated” and that the condition constituted a 0% permanent partial disability under the Minnesota Rules.  He indicated finally, as permanent restrictions, only that the employee “should avoid highly repetitive or prolonged pinching activities with his thumb,” retaining, however, the employee’s official limitation to “restricted duty.”

On July 28, 2004, the employee met with QRC Ione Tollefson for a rehabilitation consultation, and the following day QRC Tollefson reported to the employer’s insurer that she had found the employee to be a qualified employee for purposes of rehabilitation assistance.  Five days later, on August 2, 2004, the employee took a job with Swift & Company [Swift] in Worthington, Minnesota, where his weekly earnings varied, sometimes being more and sometimes being less than his pre-injury earnings with the employer.  Notice of Dr. Donovan’s MMI opinion was also served and filed on August 2, 2004.^[3]  On October 4, 2004, the employee filed a claim petition, alleging entitlement to temporary total disability benefits from June 8, 2004, through August 1, 2004, to temporary partial disability benefits continuing from August 2, 2004, and to rehabilitation services with QRC Tollefson, with a permanency claim reserved, all consequent to his work injury on September 22, 2003.  In a response filed October 18, 2004, the employer and insurer denied all benefits claimed, affirmatively asserting that the employee had been served notice of MMI on August 2, 2004, having suffered no permanent partial disability, and that he had been discharged for misconduct on or about June 11, 2004.

On November 1, 2004, the employee was examined for the employer and insurer by orthopedic surgeon Dr. K. Stephen Kazi.  In his report on that date, Dr. Kazi traced the treatment of the employee’s right thumb condition since his September 22, 2003, work injury, noting toward the end of that history that, “a week prior to this evaluation, [the employee] sustained another injury to the same thumb at [Swift] when he was hit by a piece of metal, again on the posterior aspect of the MP joint.  He presented to the company nurse, who applied a Coban bandage to the thumb and gave him Ibuprofen.”  Upon examination, Dr. Kazi found that “the examination was difficult due to an extremely high perceived rating of 9/10 for pain in the right thumb at this time” but that “[n]o objective findings were present” and “there was good stability of the collateral ligaments of the MP joint.”  Dr. Kazi diagnosed “a mild contusion of the posterior aspect of the MP joint of the right thumb,” concluding that “[n]o permanency resulted from the injury of September 22, 2003 per medical records,” that “[n]o permanent restrictions are to be expected after the new injury is resolved,” and that “[n]o additional treatment is necessary related to the work injury of September 22, 2003.”  Finally, Dr. Kazi echoed Dr. Donovan’s opinion, that the employee was at MMI with regard to the injury of September 22, 2003.

On January 14, 2005, the employee saw Dr. Donovan again, accompanied by an interpreter and QRC Tollefson, for increased pain in his right thumb MP joint.  Dr. Donovan’s records for that date report that the employee “relates he has been having increasing discomfort over the last 3 or 4 months,” that he “relates having an injury to his thumb at work where he was pulling on a sheet of metal and apparently it struck the dorsum of his thumb.  This occurred in October 2004.  He did not seek any medical attention at that time.”  Upon physical examination, Dr. Donovan noted “a boutonierre like appearance of the thumb” and “a slight increased prominence of the thumb metacarpal itself at the MP joint,” but the employee revealed “no apparent distress” and did “not appear to have an effusion of the thumb.”  Dr. Donovan diagnosed a history of gamekeeper’s thumb, status post arthrotomy of the MP joint, and probable early posttraumatic arthritis of that MP joint, and, after evidently discussing the possibility of surgery, he administered a cortisone injection.  Upon a subsequent examination of the employee on February 4, 2005, Dr. Donovan diagnosed chronic ulnar ligament laxity and recommended fusion surgery, and the employee elected to accept that recommendation, pending a second opinion.  On March 24, 2005, the employee sustained an injury to his right foot in the course of his employment at Swift.

On May 5, 2005, the employee saw orthopedist Dr. Timothy LeeBurton for a second opinion regarding a surgical treatment option.  Dr. LeeBurton noted early in his report that the employee had “a history of having an ulnar collateral ligament repair done in March of 2004,” going on to diagnose a “[f]ailed ulnar collateral ligament repair to the right thumb now with arthrosis at the metacarpophalangeal joint and a subluxated extensor pollicis longus tendon to the thumb.”  On that diagnosis Dr. LeeBurton recommended “a fusion through the metacarpophalangeal joint secondary to the incompetent ligament that could be repaired,” adding that the employee “would still end up with some element of pain in the joint secondary to his arthrosis.”  In addition to the fusion, Dr. LeeBurton recommended “a realignment procedure for his extensor pollicis longus tendon” to avoid additional problems.

On July 13, 2005, the employee filed a medical request, seeking approval of the fusion and realignment surgery being recommended by Dr. LeeBurton.  The employer and insurer filed a medical response on July 25, 2005, denying payment for the proposed surgery, and on August 17, 2005, the medical request and the employee’s October 4, 2004, claim petition were consolidated for hearing.

On August 18, 2005, Dr. Kazi conducted a follow-up examination of the employee at the request of the employer and insurer.  Upon examination, Dr. Kazi noted “a relatively severe boutonniere type deformity” that was “clearly new and has been progressive since the last evaluation of November 1, 2004.”  Dr. Kazi concluded also that he “would agree that there is some laxity of the ulnar collateral ligament associated with this deformity.”  It was Dr. Kazi’s opinion that the surgical procedure in March of 2004 had “consisted of an exploratory arthrotomy of the MP joint of the thumb,” at which time “[t]here was no tear of the ulnar collateral ligament found and no repair was performed.”  Dr. Kazi indicated that “[t]he causation issues with regard to the boutonnier’s deformity of the thumb are complex.”  He indicated that,

On September 19, 2005, Dr. LeeBurton reported briefly and directly to the employee’s attorney regarding his May 5, 2005, second opinion consultation with the employee.  In his report, Dr. LeeBurton makes reference to the employee having “had an ulnar collateral ligament repair done by a different orthopedic surgeon in March of 2004.”  He goes on to state there that the employee “appears to have laxity through the ulnar collateral ligament, which is the ligament that was repaired in March of 2004," that “[h]e also has arthrosis in the metacarpophalangeal joint,” that “[i]t does appear that his injury to the ulnar collateral ligament did lead to arthrosis in the metacarpophalangeal joint,” and that “the painful symptoms that he has at this time would only be reli[e]ved by a fusion through the metacarpophalangeal joint and not with a repeat ulnar collateral ligament repair.”

On that same date, September 19, 2005, Dr. Donovan reported also directly to the employee’s attorney, specifically in light of Dr. Kazi’s report of August 18, 2005.  After essentially reviewing the history of his treatment of the employee’s right thumb injury, Dr. Donovan rendered an opinion that it was the injury of September 22, 2003, that was “the inciting event” resulting in the pain in the employee’s right thumb and the arthritis in his right MP joint.  “[E]ither because of the injury or the natural progression of the arthritis,” he went on, “[the employee] has developed some degree of instability and subluxation of the extensor tendon.”  On that conclusion, he went on to state, “It would be my medical opinion that further surgery which would include the fusion of the thumb MP joint and attempted realignment of the extensor tendon would be related to [the employee’s] work-related injury of 9/22/03.”

The matter came on for hearing on September 20, 2005.  Issues at hearing included (1) the employee’s entitlement to temporary total disability benefits from June 8, 2004, through August 1, 2004, the day before the employee found employment with Swift, (2) the employee’s entitlement to temporary partial disability benefits from August 2, 2004, through March 24, 2005, the date on which the employee sustained his right foot injury at Swift,^[4] and (3) the causal relationship between the employee’s work injury and his need for the proposed right thumb surgery, which the parties stipulated to be reasonable and necessary and so otherwise compensable.  At hearing, the employer and insurer argued as follows: that the employee’s termination from the employer in June of 2004 was effectively for misconduct committed by the employee on June 8, 2004, and therefore the employee had forfeited any continuing entitlement to temporary total disability benefits, pursuant to Minn. Stat. § 176.101, subd. 1(e)(1) (2000); that the employee reached MMI with respect to his work injury on July 9, 2004, pursuant to the opinion of Dr. Donovan on that date; that the event in late October 2004 at Swift constituted a new injury and a superseding intervening cause of the employee’s subsequent thumb disability; and that the employee’s September 2003 work injury was not a substantially contributing cause of the need for the recommended fusion and tendon realignment surgery.

In the course of the hearing, the employer and insurer attempted to offer into evidence, regarding the misconduct issue, Employer’s Exhibits 6 and 7, which contained two decisions of the Minnesota Department of Employment and Economic Development relevant to the employee’s unemployment compensation case subsequent to his termination from the employer, together with materials relevant to those decisions, including two unsworn witness statements “To Whom It May Concern.”  The compensation judge sustained the employee’s objection to the two exhibits, based on both the hearsay objection and application of Minnesota Statutes § 268.105, which provides in part that testimony in an unemployment compensation proceeding “may not be used or considered for any purpose, including impeachment, in any civil, administrative, or contractual proceeding, . . . , unless the proceeding is initiated by the department.”  Minn. Stat. § 268.105, subd. 5(c).  The employer and insurer themselves objected, but unsuccessfully, to admission of Dr. Donovan’s report of September 19, 2005, and Dr. LeeBurton’s reports of May 5, 2005, and September 19, 2005, on grounds that those reports were without proper foundation.

Evidence submitted at hearing included the testimony of QRC Tollefson.  Ms. Tollefson testified in part that, when she obtained a history from the employee on July 28, 2004, the employee told her that he had been terminated by the employer on June 8, 2004 - the date on which he had been sent home by Mr. Heronimus.  She testified also that, in her opinion, the job that the employee was performing at the time of his termination was not within his restrictions.  She testified further that, on the date of her consultation, less than three weeks after Dr. Donovan’s MMI opinion, the employee “was continuing to have quite a bit of difficulty with right thumb pain” and “was unable to do any pinching and also had difficulty with grasping.”  She testified further that the employee had never told her that he has reinjured his thumb after September 22, 2003.  She testified also that, in her opinion, the employee’s wage loss from June 8, 2004, through March 24, 2005, was directly related to his September 2003 work injury.

The employee also testified at hearing, in part that the swelling in his thumb never completely resolved subsequent to his surgery in March of 2004.  He testified that he had refused to hook up his safety harness on June 8, 2004, because doing so was physically impossible given the configuration of the equipment above the roof to which he was supposed to hook up.  He testified that, subsequent to his being sent home by Mr. Heronimus on that date, he believed he had been fired, both because of the anger in Mr. Heronimus’s voice and demeanor and because, when on previous dates he had been sent home from work by Mr. Heronimus, he had been called back again the next day by the employer’s operations manager, Ron Totten, and the matter had been resolved.^[5]  He testified further that, when he saw Dr. Donovan on July 9, 2004, the day after aggravating his injury in the parenting incident and about a month after being sent home from the employer, Dr. Donovan had informed him that the insurer had declined to pay for any further treatment.  He acknowledged in his testimony that he had reported to Dr. Kazi at his November 2004 independent medical examination that he had been injured at Swift a few days earlier, but he implied that the injury had been to his hand, not specifically to his thumb.  He testified also that, when he was reexamined by Dr. Kazi in August of 2005, Dr. Kazi did not ask him about his October 2004 injury at Swift.

Also testifying at hearing were Mr. Menting, Mr. Heronimus, and Mr. Totten.  Mr. Menting testified in part that he did not hear the conversation between Mr. Heronimus and the employee prior to Mr. Heronimus’s sending the employee home on June 8, 2004, although Mr. Heronimus subsequently testified that Mr. Menting was in the same area as the employee at the time and “should have been able to hear.”  Mr. Menting also testified, without hesitation, that, no matter what a roofer may be doing on a roofing project for the employer, and no matter where he is on the roof, it is possible for him to get safely hooked up in his safety harness and to still do his job.  Mr. Menting also testified that the “To Whom It May Concern” statement dated September 8, 2004, over his signature in Respondent’s Exhibit 7, accurately reflected what he could recall about the incident of June 8, 2004, although it had been written up by operations manager Totten, and he had no recollection as to why it was not prepared until three month after the incident.  Mr. Heronimus testified in part that, when he sent the employee home on June 8, 2004, he did not intend to be terminating the employee, although termination would have been within company policy, in that the employee had committed a safety violation.  He testified expressly, however, that in this instance the employee “was not fired for not being hooked up,” that his termination was because there had also been several previous incidences where the employee had walked off the job or been put on suspension.  Mr. Totten also testified at hearing, in part that the employee “was not” terminated on June 8, 2004.  In the course of Mr. Totten’s testimony, the employer attempted to offer into evidence the employer’s records of the employee’s pre-June 8, 2004, misconduct, and the employee objected on grounds that those records were irrelevant and highly prejudicial.  After querying counsel for the employer and insurer as to whether his position was that the employee was discharged or that the employee voluntarily quit, and upon counsel’s answer that “He voluntarily quit.  That’s the way it appears in the employment records,” the judge sustained the objection, granting an offer of proof.

The record was left open post hearing for submission of the permitted documentation, and it closed on October 20, 2005, upon the judge’s receipt of (1) an October 10, 2005, letter argument from the employer and insurer’s attorney, attaching an undated addendum report of Dr. Kazi, (2) an October 19, 2005, response to that letter argument from the employee’s attorney, attaching internet information on Boutonniere Deformity, and (3) an October 20, 2005, objection from the employer and insurer’s attorney to that attachment.  On November 16, 2005, the compensation judge filed findings and order awarding the temporary total and temporary partial disability benefits at issue, together with payment for the proposed surgery.  The employer and insurer appeal.

In reviewing cases 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 (1992).  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, “[f]actfindings are clearly erroneous only if the reviewing court on the entire evidence is left with a definite and firm conviction that a mistake has been committed.”  Northern States Power Co. v. Lyon Food Prods., Inc., 304 Minn. 196, 201, 229 N.W.2d 521, 524 (1975).  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.”  Id.

Minnesota Statutes § 176.101 as in effect on the date of the work injury here at issue provides in part that,

Notwithstanding the testimony of their own witness, Mr. Heronimus, that the employee “was not fired for not being hooked up” on June 8, 2004, but only temporarily suspended and later terminated for not returning to work, the employer and insurer contend now that the employee’s direct disobedience of the employer’s order on that date, that he hook up his safety harness pursuant to safety requirements of OSHA, was precisely the sort of behavior that should be seen to constitute such misconduct as forfeits recommencement of benefits under the statute.  In support of their position, they cite the definition of misconduct set forth in Tilseth v. Midwest Lumber Co., 295 Minn. 372, 204 N.W.2d 644 (1973), regarding issues of misconduct in cases of unemployment compensation, which this court has applied to issues of misconduct under Minnesota Statutes § 176.101, subdivision 1(e)(1), the statute itself being without a definition.  See, e.g., Hughes v. Versa/Northern Iron, 58 W.C.D. 520, 527-28 (W.C.C.A. 1998), citing Langworthy v. Signature Flight Support, slip op. (W.C.C.A. Jul. 8, 1998); Lindsay v. Waste Management, 61 W.C.D. 34, 39-40 (W.C.C.A. 2000), citing Langworthy.  That definition limits misconduct to

With regard to the hearsay basis for the judge’s exclusion of the referenced exhibits, we acknowledge that Minnesota Statutes § 176.411 provides that compensation judges are not to be bound by “the common law or statutory rules of evidence” or by “technical or formal rules of pleading or procedure.”  In this case, however, the compensation judge’s sustaining of objection on a hearsay basis was only because the scheduled testimony of the signatories of the included “To Whom It May Concern” statements would be better evidence than those brief written statements.  That ruling does not appear to us unreasonable.  More importantly, however, we conclude that the specific express prohibition in the language of Minnesota Statutes § 268.105, which the employer and insurer do not address directly, is something quite different from the sort of more general “rules of evidence” and “rules of pleading or procedure” that are being referenced in Minnesota Statutes § 176.411.  To the extent that the two statutory provisions may be seen to be in conflict with each other, the conclusion reached by the judge is supported by application of Minnesota Statutes § 645.26, subdivision 1, which provides that, if a conflict between a general statutory provision and a special statutory provision appears irreconcilable, “the special provision shall prevail and shall be construed as an exception to the general provision . . . .”  Minn. Stat. § 645.26, subd. 1.  Here the prohibition in Minnesota Statutes § 268.105 is clearly a less general and more special statutory provision that the permissive provision in Minnesota Statutes § 176.411.

With regard to the facts otherwise in evidence, primarily in testimony, we cannot conclude that it was unreasonable for the compensation judge to conclude that the employee was not terminated for misconduct and did not voluntarily quit his job with the employer.  Testimony was ample from witnesses for both parties, and the judge had ample opportunity to assess each witness’s credibility.  In the end, the judge essentially credited nearly all of the material testimony that was offered with regard to the basis for the employee’s termination from employment.  The judge evidently found credible the employee’s own testimony that he thought he had probably been fired on June 8, 2004, and apparently would, had his being sent home been only a temporary suspension, have returned to his job had Mr. Totten called him the next day, as he always had after previous suspensions, to resolve the matter.  The judge evidently found credible also Mr. Heronimus’s testimony that the employee was expressly not terminated for not hooking up his safety harness, although such an action by the employee might have been a basis for a misconduct termination.  Neither Mr. Totten nor Mr. Menting offered any testimony material enough to render unreasonable the judge’s acceptance of Mr. Heronimus’s testimony that the employee was not terminated for misconduct or his acceptance of the employee’s testimony that he did not wilfully quit his job.  Because the judge’s conclusion on these issues was not unreasonable, and because neither the sufficiency of the employee’s post-termination job search nor the credibility of the employee’s disability and it’s relation to his work injury have been contested by the appellants, we will not reverse the compensation judge’s award of temporary total disability benefits from June 8, 2004, through August 1, 2004.  See Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.

The employee claimed temporary partial disability benefits for the thirty-three-week period from August 2, 2004, through March 24, 2005, calculating the amount on a week-to-week basis illustrated in a temporary partial disability schedule submitted into evidence as part of Employee’s Exhibit G.  That schedule reflects wage losses during eleven of the seventeen pay periods for which compensation was being claimed and no wage losses during six of those periods, the eleven affirmative wage losses also varying widely, from $2.53 to $163.08.  As corrected by the compensation judge to reflect that the employee worked only one week during the first of the two-week pay periods for which benefits were claimed, the schedule reflects that the employee’s total wage loss over the course of the thirty-three weeks of his claim was $970.65, or about $29.41 per week.  With the one correction of the exhibit referenced above, the compensation judge awarded the benefits essentially as claimed, calculated on a week-to-week basis, for a total award of $647.13 on the total $970.65 in wage losses for those months when a wage loss was registered.

The employer and insurer contend that, instead of awarding benefits calculated on a week-to-week basis based on only those months when the employee registered a wage loss, the employee’s temporary partial disability benefits should have been based on the employee’s average post-injury wage over the course of the whole thirty-three weeks of his claim, over which period of time the employee earned a total of $15,217.63.  These total earnings, they argue, result in an average post-injury weekly wage of $461.14, a figure only minimally less than the employee’s pre-injury weekly wage of $476.03, which, if benefits were to be calculated on an average basis rather than a week-to-week bases, would result in a total benefits award of $327.58 rather than $647.13.  We conclude that the judge’s award was not clear erroneous or unreasonable.

There is no statutory method for determining an employee’s post-injury wage loss for purposes of temporary partial disability compensation, and both the week-by-week method and the averaging method have been accepted by this court.  See Nutter v. United Parcel Serv., 58 W.C.D. 183 (W.C.C.A. 1997).  Moreover, the choice between those two methods is not a legal issue but a fact issue, for the compensation judge to resolve on a case-by-case basis in light of the totality of the evidence.  Murphy v. B.F. Nelson Co., slip op. (W.C.C.A. Oct. 8, 1998); see also  Erdrich v. Ford Motor Co., 49 W.C.D. 528, 534 (W.C.C.A. 1993).  We acknowledge that in Nutter v. United Parcel Service, where an employee by contract earned twice as much money during one half of the year post injury as he earned during the other half of the year post injury, we held that the compensation judge did not err by calculating the employee’s post-injury wage loss using an averaging method over a year-long period instead of calculating benefits on a week-to-week basis.  See Nutter, 58 W.C.D. at 189.  In the present case, however, particularly given the relatively minimal disparity between the two alternative results, and notwithstanding the failure of the judge to explain in his memorandum the rationale for his choice, we cannot conclude that the method of calculation chosen by the compensation judge was “clearly erroneous” under our standard of review.  Therefore, and in light also of the fact that the particular mode of calculation was not clearly at issue before the judge, we decline to reverse or modify the compensation judge’s award of temporary partial disability benefits.  See Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.

At Findings 21 and 22 and Order 1, the compensation judge concluded that the employee was entitled to the proposed surgery as a consequence of his work injury of September 22, 2003, having concluded at Finding 14 that the employee would not be at MMI until he has had and recovered from that surgery.  The employer and insurer contend that Dr. Donovan’s MMI opinion on July 9, 2004, is unopposed medical evidence that the employee was already at MMI as of that date and that whatever need the employee may now have for surgery is not causally related to his September 22, 2003, work injury.  They contend that the need for that surgery was caused not by the September 2003 work injury but by the employee’s late October 2004 incident at Swift, which they argue was “a new injury and an efficient superseding/intervening cause.”  They argue that Dr. Donovan’s September 19, 2005, report implying an opinion to the contrary was hurriedly prepared for hearing, is inconsistent with that doctor’s other medical records, and so is of insufficient foundation to be relied on.  They contend further that Dr. LeeBurton’s opinion of September 19, 2005, similarly relating the employee’s need for surgery to his September 2003 work injury, is also of insufficient foundation, in that it is based on that doctor’s mistaken assumption, as reflected in both his May 5, 2005, report and his September 19, 2005, report, that the employee’s UCL was repaired in March of 2004, six months after his September 2003 work injury.  They argue further that the compensation judge erred in apparently receiving into evidence and considering in his decision the information on Boutonniere Deformity that was attached by the employee as Exhibit “a” to his response to the employer and insurer’s post-hearing letter argument attaching Dr. Kazi’s addendum medical report.  They contend therefore that either the surgery award should be reversed outright or the issue should be remanded to the compensation judge with instructions either that he refrain from relying on the opinions of Drs. Donovan and LeeBurton or that the employer and insurer be allowed an adequate remedy, including permission to take post-hearing depositions of Drs. Donovan and Kazi.  We are not persuaded.

Maximum medical improvement is statutorily 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."  Minn. Stat. § 176.011, subd. 25.  A finding of MMI is not a purely medical conclusion but is a finding of ultimate fact.  Hammer v. Mark Hagen Plumbing & Heating, 435 N.W.2d 525, 528, 41 W.C.D. 634, 639 (Minn. 1989).  The "medical probability" addressed in the statutory definition of the term is established by numerous factors, including not only the opinion of physicians but also the history of improvement, current treatment, pre-existing conditions, proposed treatment, vocational experts' statements, and testimony at the hearing.  Id. at 529, 41 W.C.D. at 639.  While the employee may have appeared to Dr. Donovan in July of 2004 to have been at MMI, the compensation judge was not bound to rely on that conclusion.  In this case, there is ample evidence to reasonably support the judge’s decision that the employee’s September 2003-related condition might yet be improved by surgery.  This evidence includes recent diagnostic opinion and evidence of surgical treatability, the evident continuity of pain since the work injury prior to which there had been no thumb problems, the current medical recommendations of surgery, QRC Tollefson’s supportive testimony, and the employee’s own testimony of continuous pain and hope in the surgical option.

Nor are we persuaded by the employer and insurer’s affirmative argument that the employee’s current need for surgery is related to a work injury at Swift in October of 2004 instead of to his September 2003 work injury.  Regardless of the nature of the aggravating incident at Swift in late October 2004, there is ample evidence of record that the employee had been in continuing thumb pain since the date of his September 2003 injury with the employer and that the fusion and tendon realignment now proposed are reasonable and in fact, at least with regard to the realignment, anticipated consequences of that injury.  For compensation to be due, it is unnecessary to show that an injury is the sole cause of the disability, only that it is “an appreciable or substantial contributing cause.”  Roman v. Minneapolis St. Ry. Co., 268 Minn. 367, 380, 129 N.W.2d 550, 558, 23 W.C.D. 573, 592 (1964).  That something more or less injurious to the employee’s thumb may or may not have occurred in the course of the employee’s work at Swift is not dispositive with regard to the issue of whether or not the employee’s 2003 work injury reasonably contributed to his need for the recommended surgery.  Concluding that it was not unreasonable, in light of the entire record as a whole, for the judge to conclude that continuing effects of the employee’s September 2003 work injury contributed to his need for the surgery, we affirm the compensation judge’s award of the fusion and tendon realignment surgery that is here at issue as treatment for the employee’s work injury.  See Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.