The employer and insurer Royal Insurance Group appeal from the compensation judge's finding of a permanent Gillette-type injury on April 28, 1999, and/or from the judge=s assignment of liability on Royal Insurance Group based on such an injury or on the employee=s work injury of April 12, 1996.  We affirm the finding of a Gillette-type injury on April 28, 1999, and of substantial causation by the 1996 injury, but we remand for further consideration, findings, and possible apportionment with regard to the liability issue.

BACKGROUND

Beginning apparently in about 1990, Debra Burke has sustained several work-related injuries to her spine while employed with Precision Engineering, including a low back injury on April 12, 1996, on which date she was thirty-eight years old and earning a weekly wage of $389.60.  At the time of that injury, Precision Engineering [the employer] was insured against workers= compensation liability by Royal Insurance Group [Royal], which accepted liability and commenced payment of benefits.  Ms. Burke [the employee] eventually underwent a discography, which revealed, according to the subsequent operative report, Asignificant concordant pain with injection of [L]3-4, [L]4-5, and [L]5-[S]1.@  AThe two most involved levels@ were determined to be L4-5 and L5-S1, and on October 30, 1997, the employee underwent a lumbar laminectomy at L4-5, discectomies at L4-5 and L5-S1, and a posterior fusion from L4 to S1, performed by Dr. Andrew Smith.  Following this surgery, the employee returned to work for the employer at lighter duty, in March of 1998.  In a report to the employee=s attorney dated October 7, 1998, the employee=s treating physiatrist, Dr. Alan Bensman, rated the employee=s permanent partial disability at 22% of the whole body, based on her condition at L4 to S1.  In that same report, Dr. Bensman issued Apermanent restrictions because of the injuries sustained on April 12, 1996,@ noting  near the end of his report A[t]he possibility of her having progressive degeneration at the L3-4 level.@

On October 8, 1998, the employee sustained a temporary aggravation of her back condition.  Although she was initially able to continue working after this injury, her pain increased, and on October 12, 1998, Dr. Bensman prescribed bed rest, medication, and cold packs, referring her two days later also for two weeks of physical therapy.  The employee was off work thereafter for about one week and then returned to work for the employer part time, with a gradual increase in hours per day.  On December 8, 1998, Dr. Bensman reported that the employee=s symptoms were generally better, although she had an increase in left hip pain.  He stated that the employee was at that time clinically demonstrating left L5 nerve root involvement but that there did not appear to be any active irritation.  He indicated that he had contacted the employee=s exercise physiologist and that they had agreed to modify or discontinue certain back extension exercises that were aggravating the employee=s symptoms.  Dr. Bensman concluded that the employee was at maximum medical improvement [MMI] with regard to the October 1998 exacerbation.

On January 1, 1999, the employer=s workers= compensation liability coverage was temporarily shifted from Royal to Liberty Mutual Insurance Company [Liberty].  Two months later, on March 1, 1999, the employee returned to see Dr. Bensman, complaining of an increase in left hip and thigh pain, with symptoms increasing with work.  The doctor noted upon examination that there was Aincreased lumbosacral and iliolumbar ligament involvement as well as irritation of the gluteal, piriformis and quadratus muscles,@Asignificant tightness of the left iliotibial band,@ and Aresidual left L5 nerve root involvement@ but Ano evidence of active nerve irritation.@  Upon these findings, the doctor prescribed physical therapy, continued the employee=s restrictions, and recommended extension of her health club membership.

The March 1, 1999, appointment with Dr. Bensman was the employee=s only medical visit during the first three months of 1999.  On April 1, 1999, she left on a planned vacation to Mexico, and she returned to her job with the employer on April 11, 1999.  On April 16, 1999, Royal reassumed from Liberty the risk for the employer=s workers= compensation liability.  On April 28, 1999, the employee saw Dr. Bensman again, who reported that she was complaining on that date of Aa significant increase in low back and left leg symptoms since about 4/21/99.@  He indicated that the pain was Anow radiating into the left foot following primarily in L5 and possibly S1 dermatome.@  He stated, AInitially she was having increased low back symptoms at work, and the foot symptoms have come on in the last several days.  She specifically denied any new injuries or other events that caused this.@  He went on to indicate that the employee had been feeling better during her recent vacation to Mexico but that Athe symptoms increased when she returned to work.@  Dr. Bensman concluded that A[c]linically she presents with an exacerbation of the lumbosacral and gluteal myofascial areas of involvement,@ noting that A[t]here is also clinical evidence of increased left L5 and S1 nerve root irritation.@  In light of these findings, Dr. Bensman prescribed medication and restricted the employee from working.  On April 28, 1999, the employee was forty-one years old and was earning an average weekly wage of $404.80.

Still off work, on June 1, 1999, the employee underwent an MRI scan of her lumbar back.  In a June 17, 1999, report to Dr. Smith, Dr. Bensman indicated that the MRI had revealed Aevidence of retrolisthesis and a small left foraminal disc herniation which is causing slight displacement of the left L3 nerve,@ together with some facet degeneration.  Minimal retrolisthesis and mild disc dehydration at L2-3 were also observed, but there was no observable evidence of disc herniation or stenosis.  In a letter on that same date to the employee=s attorney, Dr. Bensman indicated that the retrolisthesis at L3 Ahas been progressively occurring since the fusion@ and that, in his opinion, Aall of the present findings are related to the injuries that were initially sustained on 4/12/1996.@

On July 12, 1999, the employee was examined for the employer and Royal by Dr. Mark Friedland, whose examination included taking a detailed history from the employee and reviewing her medical records.  Based on that examination, Dr. Friedland diagnosed A[s]tatus post L4-5 and L5-S1 decompressions with L4-5 discectomy and solid intertransverse process posterolateral fusions from L4 to the sacrum,@ together with mild to moderate L2-3 and L3-4 degenerative disc disease.  It was Dr. Friedland=s conclusion in part that there was Aabsolutely no indication based on the [employee=s] physical examination, or medical records that her current problems have any causal or relationship to her original injury of April 12, 1996.@  It was also Dr. Friedland=s conclusion that there was Ano objective evidence on the MRI scan of June 1, 1999 current radiographs or physical examinations that would indicate any temporary aggravation or worsening of her L2-3, and L3-4 degenerative disc disease of an objective nature.@  Nor was there, he concluded, any acute disc herniation, notwithstanding the fact that the employee=s Afusion surgery [at L4 through S1] in my opinion does place some slightly greater stresses upon the upper mobile levels of the lumbar spine.@  Dr. Friedland concluded that the employee was not in need of any further medical or chiropractic treatment, was not a candidate for any further surgical intervention, and was capable of full-time employment within certain permanent restrictions.  It was Dr. Friedland=s further opinion that the employee had not sustained any significant injury in October 1998 and that she had reached MMI from whatever injury she did sustain at that time by December 8, 1998, without any related permanent impairment.

On July 13, 1999, the employee returned to see Dr. Smith, on referral from Dr. Bensman Afor reevaluation of a possible new problem, related of course to the old work injury, but an extension to the disc above the two that were previously fused.@  Dr. Smith reported on that date that, following her L4-5 and L5-S1 surgery, the employee Awas feeling much better and then over the last several months she has gradually gotten recurrent back pain.@

By late June 1999, Royal had paid the employee 104 weeks of temporary total disability benefits consequent to the employee=s April 1996 work injury, and on July 19, 1999, the employee filed a claim petition alleging entitlement to compensation for temporary total disability continuing from April 29, 1999, consequent to her work injury on April 12, 1996.  In their answer filed July 23, 1999, the employer and Royal denied liability for the claim and requested that the petition be dismissed.  The employee requested a priority hearing at a scheduled settlement conference.

The employee remained off work through the end of 1999, and Dr. Bensman eventually prescribed physical therapy and referred her to Dr. Smith for a surgical evaluation.  Dr. Smith  recommended bilateral hemilaminotomies and discectomies at L3-4, with posterolateral anterior transverse process fusion at that level, which he performed on February 23, 2000, with Dr. Mark Gregerson, the operative report indicating that the back and leg pain being treated were Asecondary to instability at L3-L4.@  Following recuperation from the surgery, the employee undertook, in the summer of 2000, several months of vocational rehabilitation assistance with Brezinski & Associates. 

On June 6, 2000, the employee returned to be reexamined by Dr. Smith.  In a letter on that date to the employee=s attorney, Dr. Smith indicated that, subsequent to undergoing her surgery at L4-5 and L5-S1, the employee Ahad a new injury, this time affecting the L3-4 level as opposed to L4-5 or L5-S1 and it was in conjunction with lifting and pushing and pulling when she went back to work after the previous work-related injury had healed sufficiently.@  Dr. Smith went on to state, AThe only relationship to the previous work-related injury in my opinion is the fact that it was in the same part of the spine but as I mentioned this would, in my opinion, reflect a new injury.@  Dr. Smith went on, AIn my opinion, the work activities as described to me by the patient just before the reinjury to her back were the cause of this new injury and were in fact lifting, pushing, pulling, and those sorts of things as described to me by the [employee].@  Dr. Smith does not mention a specific date on which the Anew injury@ to which he refers occurred.

On June 8, 2000, the employee was examined again for the employer and Royal by Dr. Friedland.  In his report, Dr. Friedland indicated in part that, based on further review, including review of the employee=s deposition testimony, it was now his opinion that the employee had sustained a permanent Gillette-type injury on April 1, 1999, and that that injury was a substantial contributing factor in any perceived need for the surgery performed by Drs. Gregerson and Smith on February 23, 2000, at the L3-4 level of the employee=s spine.  Dr. Friedland indicated also, however, that he continued to believe that that surgery was medically neither reasonable nor necessary in treatment of that injury.  On August 17, 2000, Dr. Friedland essentially reiterated those opinions in testimony by deposition, expressly testifying that his opinion was Athat the April 12, 1996 injury was not a contributing factor or cause of the need for the L3-4 surgery.@

The employee=s claim against the employer and Royal for additional temporary total disability benefits and for payment of rehabilitation expenses incurred with Brezinski and Associates, based on the employee=s April 1996 work injury, came on for hearing on August 22, 2000.  By Findings and Order filed September 29, 2000, the compensation judge concluded in part that the employer and Royal should pay temporary total disability benefits based on the 1996 injury beginning April 28, 1999, until the 104-week statutory cap was reached and that the employee should seek vocational assistance with the Minnesota Department of Labor and Industry Vocational Rehabilitation Unit.

On October 23, 2000, the employee filed a Second Amended Claim Petition, alleging against both the employer and Royal and the employer and Liberty entitlement to compensation for temporary total disability continuing from April 29, 1999, and also to payment of over $22,000 in medical expenses, both consequent to work injuries on April 1, 1999, and April 29, 1999, in addition to the April 12, 1996 injury.  In their answer, filed November 1, 2000, the employer and Liberty denied the petition, on grounds including that any injuries at issue had occurred while Liberty was not on the risk.

On January 26, 2001, the employee was examined for the employer and Liberty by Dr. H. William Park.  In his report on that date, Dr. Park indicated in part that he did not find any objective evidence to support a finding of a Gillette or any other type work injury on or about April 1, 1999.  He noted that the employee had been totally disabled since April 28, 1999, and he concluded that all of her medical treatment had been reasonable and necessary for curing and relieving the effects of her April 1996 work injury, which had in turn permanently aggravated a degenerative disc disease condition pre-existing it.  Dr. Park concluded also that the employee should be subject to certain lifting, bending, and movement  restrictions, that responsibility for her disability and medical expenses should be apportioned 50% to the condition that pre-existed her April 1996 injury and 50% to that injury itself, that the employee had reached MMI, and that the employee was in need of a QRC and Aof future medical treatment if there are recurrent problems, especially above the fusion level.@

The matter came on for hearing on March 30, 2001.  Issues at hearing included whether or not the employee had sustained a work injury subsequent to her April 12, 1996, injury and, if so, when did such an injury occur and how should liability for it be apportioned.  Also at issue was the employee=s entitlement to payment of medical expenses in conjunction with the three named intervenors, and reimbursement to intervenor Minnesota Department of Labor and Industry/VRU for rehabilitation services.  At the hearing, the employee testified in part that she did do some walking and sightseeing while she was on vacation in Mexico in early April 1999, but no evidence was rendered to suggest that the employee sustained any injury to her back while she was there.  Nor could the employee testify to recalling any incident or unusual occurrence on April 21, 1999, or articulate any specific change in her back condition between her return to work on April 11, 1999, and April 29, 1999.

By findings and order filed July 23, 2001, the compensation judge concluded in part as follows: (1) that, additional to her April 12, 1996, work injury, the employee had sustained a temporary work injury in the nature of an aggravation to her back on October 8, 1998; (2) that she had sustained a permanent Gillette-type injury on April 28, 1999; (3) that she was temporarily totally disabled from June 26, 1999, through February 27, 2001; (4) that she was temporarily partially disabled from February 28, 2001, to the date of the hearing; (5) that all medical treatment rendered to the employee from April 1999 through the date of hearing was reasonable and necessary to cure and relieve the effects of both the April 1996 injury and the April 1999 injury; (6) that both the April 1996 injury and the April 1999 injury were causative factors in the employee=s need for medical care and time off work as of April 28, 1999; (7) that the rehabilitation services provided to the employee were reasonable and necessary in the attempt to rehabilitate her from the effects of those injuries; (8) that the employer and Royal were liable for compensation for the employee=s temporary total disability from June 27, 1999, through February 27, 2001, and for her temporary partial disability from February 28, 2001, through the date of hearing, based on the April 28, 1999, work injury; and (9) that the employer and Royal were also liable for all claimed medical and rehabilitation benefits, apparently based on its being on the risk at the time of both the April 1999 Gillette injury and the employee=s work injury of April 12, 1996.  The employer and Royal appeal.

STANDARD OF REVIEW

In reviewing cases on appeal, the Workers= Compensation Court of Appeals must determine whether Athe 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, Athey 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, A[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, Aunless 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.

DECISION

1.  The Date of the April 1999 Gillette Injury

The employee was taken off work on April 28, 1999, by her long-term treating physician Dr. Bensman, who had previously attributed the employee=s need for treatment to her April 1996 or October 1998 injuries and who never thereafter rendered an opinion that any new injury occurred subsequent to October 1998.  Dr. Park, who examined the employee for the employer and Liberty, similarly never rendered any opinion that any later injury occurred.  The employee=s surgeon, Dr. Smith, concluded that a Anew injury@ occurred sometime in 1999, but he did not specify its date.  The only physician to specify a date of any post-1998 work injury was Dr. Friedland, who examined the employee for the employer and Royal and who opined that a Gillette-type injury had occurred on April 1, 1999.  The compensation judge found that the employee had sustained a permanent Gillette-type injury on April 28, 1999, the day the employee went off work, explaining in his memorandum that, although the culmination of a Gillette-type injury is not restricted to the event of the employee=s going off work due to his disability, that culmination must be marked by someAascertainable event,@ a different one if not the removal from work.  See Schnurrer v. Hoerner Waldorf et al., 345 N.W.2d 230, 233, 36 W.C.D. 504, 508 (1984); see also Ellingson v. Thriftway, Inc., 42 W.C.D. 565 (W.C.C.A. 1989).  The judge reasoned that A[i]n this case, the going on vacation on April 1, 1999 is not a factually >ascertainable event= that would establish an injury at that time.@  The employer and Royal expressly Ado not dispute that a Gillette injury occurred resulting from the Employee=s work activities between on or about January 1, 1999 and sometime in or about April of 1999,@ but they do dispute that the culmination of that injury occurred on April 28, 1999.  We conclude that the judge=s dating of the injury was not unreasonable.

The employee=s history of back problems is extensive, and even the record of her treatment in the spring of 1999, though relatively limited, contains several elements any one of which the compensation judge might reasonably have identified as an Aascertainable@ culmination point in the employee=s disability sufficient to mark a Gillette-type injury.  The employee=s actual removal from work, however, was clearly the most prominent of these and therefore a very reasonable Aascertainable event@ in the history of the employee=s problems--one clearly sufficient to mark the specific date of an injury that neither party any longer contests.  Because it was not unreasonable, we affirm the judge=s dating of the employee=s Gillette injury.  See  Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.

2.  Royal=s Liability for the April 28, 1999, Gillette Injury

Liberty had been on the risk for the employer=s workers= compensation liability for all but nine working days of the four months immediately preceding the date of the Gillette injury here affirmed.  Nevertheless, having concluded only Athat the culmination date should be April 28@ (emphasis added), the compensation judge reasoned in his memorandum that

Royal Insurance Company is the responsible party in this matter since it is the insurer for the April 12, 1996 injury and was on the risk at the time of the culmination of the Gillette injury on April 28, 1999.  Wage loss benefits shall be paid to the employee by Royal based on the April 28, 1999 injury.

It is unclear from this statement, or from the rest of the judge=s decision, whether or not the compensation judge considered the fact that liability for a Gillette-type injury does not necessarily attach arbitrarily to the carrier who is on the risk at the time of the injury.  See Tannahill v. Mid-American Lines, Inc., 40 W.C.D. 726, 728 (W.C.C.A. 1987) (an insurer=s liability for a Gillette-type injury is Asubject to the finding that during the last period of employment the work duties performed by the employee must have been a substantial contributing factor [in] the employee=s disability).@

As the employer and Royal have argued, Aimposition of liability on the last insurer is not automatic but must rest on proof connecting the employee=s disability to the employee=s job duties during that insurer=s period of coverage.@  Crimmins v. NACM North Central Corp., 45 W.C.D. 435, 439 (W.C.C.A. 1991).  In his findings and order, the compensation judge failed to address the issue of whether the employee=s work from April 16, 1999, through April 28, 1999, was a substantial contributing factor in her Gillette injury.  We therefore remand to the compensation judge for reconsideration and further findings in the matter of liability for the employee=s April 28, 1999, Gillette-type injury.  The judge should focus his reconsideration on the question of whether or not the employee=s work activities during each insurer=s period of coverage constituted a substantial contributing factor in the April 28 injury, and he should make findings to support his decision.

3.  Royal=s Liability for Post-April 1999 Benefits Based on the April 1996 Work Injury

In Finding 38 the compensation judge found the employee=s post-April 1999 medical care reasonable and necessary treatment for her April 1999 Gillette-type injury and her April 1996 work injury, and in Finding 40 the judge found both of those injuries causally related to the employee=s need for that care and for time off work as of April 28, 1999.  In Finding 41, the judge also found that the employee=s rehabilitation services had been reasonable and necessary in rehabilitating her from Athe effects of the personal injuries.@  The employer and Royal contend that substantial evidence does not support the compensation judge=s conclusion that the 1996 injury is in any way contributory to the employee=s need for her February 2000 surgery or for any medical expenses or total or partial disability subsequent thereto.  In support of their position they cite the records and reports of the employee=s treating surgeon, Dr. Smith, and of independent examiner Dr. Friedland, to the effect that the problems at L3-4 that compelled the February 2000 surgery constituted a Anew injury@ at a Anew level of the spine,@ from which injury flow all benefits awarded in this proceeding.  We are not persuaded, but we remand this issue also, for a possible apportionment determination, contingent on the compensation judge=s conclusion as to liability for the 1999 Gillette-type injury.

We acknowledge that, as argued by the employer and Royal, Dr. Smith found a totally Anew injury@ subsequent to the 1996 injury, that Dr. Friedland attributed any necessity for the February 2000 surgery to an injury on April 1, 1999, and that that doctor also testified in his August 2000 deposition that the 1996 injury was expressly not a substantial contributing cause of the employee=s post-April 1999 problems.  The medical records and reports of Dr. Bensman, however, together with the report of Dr. Park, the operative reports of Dr. Smith, and even some implications in Dr. Friedland=s records, contain substantial evidence to support the conclusion reached by the judge--essentially that the employee=s 1996 injury is a substantial contributing cause of the employee=s need for medical care and time off form work after April 28, 1999.

On October 7, 1998, Dr. Bensman, in issuing permanent restrictions related to his 22% permanency rating of the employee=s condition at L4 through S1, warned expressly that the employee might have Aprogressive degeneration at the L3-4 level.@  In his June 17, 1999, correspondence, subsequent to the employee=s April 1999 Gillette injury, Dr. Bensman noted that retrolisthesis evident at L3 on the June 1, 1999, MRI scan had been Aprogressively occurring since the fusion@ and that, in his opinion, Aall of the present findings are related to the injuries that were initially sustained on 4/12/1996.@  In addition to this evidence from Dr. Bensman=s records are the October 1997 and February 2000 operative reports of Dr. Smith, both of which implicate level L3 of the employee=s spine in his lumbar condition already in 1996, the first documenting concordant pain at that level already in 1997 and the second referencing the Ainstability@ at L3 that had been warned of at the time of the earlier surgery.  Even Dr. Friedland himself indicated, in his July 12, 1999, report, that the employee=s 1996 fusion from L4-S1 Adoes place some slightly greater stresses upon the upper mobile levels of the lumbar spine.@

Given the overall record, including the positive discogram at L3-4 before the 1997 fusion surgery, the likelihood of consequent problems above the site of that surgery as attested to even by Dr. Friedland, and the opinions of Drs. Park and Bensman that the 1996 injury is the cause of the employee=s current problems, we cannot conclude that it was unreasonable for the compensation judge to find that the employee=s 1996 work injury was a substantial contributing factor in her post-April 1999 need for medical care, time off work, and rehabilitation assistance.  Therefore we affirm that finding.  See  Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.

Our affirmance on this issue, however, may have an impact on the compensation judge=s obligations on remand.  Should the compensation judge find, upon remand, that the employee=s work activities during Royal=s period of coverage in the spring of 1999 were not a substantial contributing factor in the employee=s Gillette injury on April 28, 1999, the judge will need to apportion liability between the two insurers.