MAZE-ROTHSTEIN, J.

This is a cross appeal from a decision that awarded some compensation benefits to a deceased employee's widow, but denied others. Because the judge failed to apply the definition of "personal injury" contained in G.L.c. 152, § 1(7A), St. 1991, c. 398, § 14, we vacate the decision and remand the case for further findings consistent with this opinion.

This case illustrates how a minor physical insult when superimposed on a fragile state of health can set in motion a chain reaction with catastrophic results. See G.L.c. 152, § 1(7A) as amended St. 1991, c. 398, § 14.

The employee, a diabetic since 1985, worked as a maintenance man for Riverside Management at the Forest Hills Apartment Complex. On October 16, 1992, while in the course of his employment, he tripped and fell on steps, injuring the fifth toe of his left foot. (Dec. 5-6.) This relatively insignificant episode apparently forever disrupted the employee's delicate balance of health.

His toe did not heal. Instead the damaged toe tissue became gangrenous. The employee treated briefly on an outpatient basis, but on November 2, 1992 he was hospitalized for further treatment of his toe. So began his steep downward spiral. In fact, after admittance, the employee never left the hospital until his death approximately two months later. First, his left toe was amputated. Next, a vein was transplanted to his left leg, followed by insertion of a filter into the same leg. When these invasive steps failed to improve his condition, part of his left foot was amputated. Shortly thereafter, he required a partial amputation of the left leg. (Dec. 7.) These insults to his system apparently left his state of health greatly weakened. He sustained a myocardial infarction and multiple major organ failure of his kidneys, liver, and lungs. The employee died on February 14, 1993, a few weeks before his 54th birthday.Id.

The claimant's widow, filed a claim requesting §§ 30, 31, 33, 34 and 36(g), (h), (j) and (k) benefits under the provisions of G.L.c. 152. These claims were denied after conference in an order filed on March 24, 1993. She appealed for a full evidentiary hearing. (Dec. 2.)

Because this was a death case, the parties chose to "opt out" of the § 11A medical examination. See 452 Code Mass. Regs. 1.10(5). (Dec. 3.) Dr. James Menzoian, a general and vascular surgeon and the employee's treating physician, provided the only medical evidence submitted. The insurer introduced no medical evidence.

In subsidiary findings, the judge carefully set out Dr. Menzoian's hospital admission diagnosis: gangrene of the toe, cellulitis of the foot and peripheral vascular occlusive disease, probably related to arteriosclerosis and diabetes mellitus. (Dec. 8.) The doctor opined that the toe injury caused cellulitis and gangrene to develop requiring hospitalization. (Dec. 8.) Moreover, the doctor opined that all that had happened during his hospitalization, including the amputations, disfigurement, and his final demise by total organ failure was related to the left fifth toe injury. (Dec. 8-9.)

Having made these subsidiary findings, the judge concluded in her general findings that the employee sustained a compensable industrial injury to the fifth toe of his left foot on October 16, 1992. But without explanation and contrary to her subsidiary findings, the judge ruled that the claimant failed to meet her burden of proof that the failure of the decedent's liver, kidneys, lungs, or general disfigurement were related to the October 16, 1992 toe injury. (Dec. 12.) Instead, she found that the employee died ultimately from organ failure related to his severe pre-existing medical problems, namely diabetes and coronary artery disease. (Dec. 11-12.)

Next, the judge ordered § 34 temporary total incapacity benefits from October 16, 1992 to February 14, 1993. (Dec. 13-14.) Despite finding a failure of proof causally connecting the employee's demise and his October 16, 1992 toe injury, the judge nevertheless ordered § 31 widow's benefits from February 14, 1993 and continuing, §§ 30 medical costs, § 33 burial expenses, applicable § 50 interest and § 13A attorney's fees to employee counsel. Section 36 loss of function benefits were awarded only for the amputation of the left toe. (Dec. 14.)

Both parties appeal. The insurer argues that the decision is contrary to law because a finding of no causation between the toe injury and the employee's death requires a denial not an award of widow's benefits. The insurer also argues that the judge failed to apply the standard of proof of causation contained in G.L.c. 152, § 1(7A). The claimant, on the other hand, seeks affirmation of the § 34 temporary total and the § 31 dependent's compensation order, but requests that the reviewing board align the general findings with the subsidiary findings that connect the toe injury to the employee's death. The claimant also seeks an award of § 36(h), (g), (j) and (k) benefits for the permanent losses of function to the left foot, left leg, liver, lungs, kidneys and for bodily disfigurement, and a corrected amount for the loss of the toe. Because we vacate the decision and recommit the case, we need not address the ancillary issue of § 36. Instead we leave it to the judge to reevaluate on remand.

Dispositive of the issues on appeal is our agreement that the decision lacks the necessary application of § 1(7A), which by St. 1991, c. 398, § 14, amended the definition of "personal injury" under the Act:

If a compensable injury or disease combines with a pre-existing condition, which resulted from an injury or disease not compensable under this chapter, to cause or prolong disability or a need for treatment, the resultant condition shall be compensable only to the extent that such compensable injury or disease remains a major but not necessarily predominant cause of disability or need for treatment.

Id. (Emphasis added). Because causal relation is a question of fact and law for the judge to determine, we must vacate the decision and remand the case for an application of the correct standard of causation for this 1992 injury.

Amidst the vortex of disputed liability was the question of whether the employee's precipitous decline from the sequential and increasingly radical treatments ending in his demise, was causally related to the original toe injury. Its proof was a matter beyond the common knowledge of ordinary lay people and had to rest on expert testimony. Sevigny's Case, 337 Mass. 747, 751 (1958); Lewis v. Walco, Inc., 5 Mass. Worker's Comp. Rep. 3, 4 (1991).

The only medical evidence in the record demonstrated a lengthy but unbroken chain of causation from the toe injury to the employee's death. While the judge was free to reject the uncontradicted opinion of Dr. Menzoian, she could only do so if she set out reasons which could be properly made from the evidence submitted. Jones v. Sylvania Products, 7 Mass. Workers' Comp. Rep. 347, 349 (1993) and cases cited; see Galloway's Case, 354 Mass. 427, 431 (1968). We could easily agree with the employee that the judge's conclusion contrary to the doctor's on causation would be reversible, were this simply an "as is" personal injury. Said liability standard was first explicated in Madden's Case, 222 Mass. 487 (1916):

The previous condition of the employee's health is of no consequence in determining the amount of relief to be afforded. . . . [I]t is the hazard of the employment acting upon the particular employee in his condition of health and not what the hazard would be if acting upon a healthy employee or upon the average employee. The act makes no distinction between . . . healthy or diseased employees. All who rightly are describable as employees come within the act.

Id. at 494. However, enactment of St. 1991, c. 398, § 14, has modified the foregoing standard of relief under the worker's compensation system for employees with pre-existing conditions that are not work-related. For employees, like the decedent, whose particular fragility was due to his diabetes and arteriosclerosis, § 1(7A) now imposes the elevated requirement that industrial injury be "a major but not necessarily predominant cause" of the resultant medical disability.

At the outset we must emphasize that § 1(7A)'s 1991 amendment does not change the basic definition of "personal injury" for most other types of injuries under the Act. Specifically, all industrial injuries that do not combine with a pre-existing non-compensable condition, as well as those that combine with a compensable pre-existing condition, are still assessed under the same "as is" standard that has governed industrial injuries since the 1913 inception of c. 152. It is only those personal injuries that do combine with a non work-related pre-existing condition that must meet the qualification that "the resultant condition shall be compensable only to the extent such compensable injury or disease remains a major but not necessarily predominant cause of disability or need for treatment."

The instant case presents a scenario that calls for application of this new standard. The judge did not apply it and for this reason we remand the case for further findings.

We will not pass over the bedevilling ambiguities and complexities of the new § 1(7A) in silence, however. In Hammond v. Merit Rating Board, 10 Mass. Workers' Comp. Rep. ___ (1996), we saw this storm on the horizon, and stated that:

Conceivably, if a minor event is the proverbial "straw that breaks the camel's back" when a previously stable non-work related pre-existing condition needs only a small trigger to blossom into incapacity, then such triggering work event could arguably be [a] "major" cause of medical disability. In such instances, in order to determine whether that disability has "as a major cause the work-related injury," the judge will have to determine if the work injury set off an identifiable causal chain that would otherwise have remained quiescent.

Id., emphasis added. The case at bar requires we continue the analytical process commenced in Hammond, supra.

With the 1991 amendment, § 1(7A) has become a multifaceted standard, and so we examine its individual components in an effort to ferret out its meaning. First, the pertinent language suggests that judges must make specific findings on: 1) whether there was a physical change (and what it was) occasioned by an event arising out of and in the course of the employment (or an industrial injury as it has always been understood); and 2) whether the industrial injury combined with an identified "pre-existing condition, which resulted from an injury or disease not compensable under this chapter, to [;3)] cause or prolong disability. . . ." This passage appears to call on judges to conduct nothing more than a "but for" analysis. To wit, judges must find whether but for the combination of a work event and a non-work related prior condition, there would not be a compensable injury or need for treatment. Here the medical evidence would appear to point toward a finding that there was causation by way of a medically disabling combination of a work event and pre-existing condition.

Next, once caused or prolonged, the medical disability or "resultant condition" is then compensable "only to the extent that such industrial injury "remains a major but not necessarily predominant cause . . . ." Id. (Emphasis added). There is no small measure of ambiguity in the statutorily undefined phrase "remains a major . . . cause." G.L.c. 152, § 1(7A). (Emphasis added). We therefore look to construe it within the "ordinary and approved usage of language, considered in connection with the cause of its enactment, the mischief or imperfection to be remedied and the main object to be accomplished, to the end that the purpose of its framers may be effected." Jinwala v. Bizzaro, 24 Mass. App. Ct. 1, 3 (1987) and cases cited. The primary definition of "remain" is "[t]o continue without change of condition, quality or place." American Heritage Dictionary, 2d College Ed. (1985). In other words, judges must find whether the compensable injury that combined with the pre-existing noncompensable condition to cause disability or needed treatment continues to be "a major cause", among any number of major causes of medical disability throughout the course of extended physical effects, by contemplating not the magnitude of the incident itself, but the harm flowing specifically from the industrial injury. AccordRobinson's Case, 416 Mass. 454, 459 (1993) (in mental injury cases, employee not required to prove events were themselves significant, but that whatever the events were, they significantly contributed to cause the disability). In our view, the 1991 revision to the language of § 1(7A) now contemplates situations where work injuries, regardless of magnitude may fade to the status of less than a major cause. However, by the very words of the statute "a major cause" need "not necessarily" be "the predominant cause". G.L.c. 152, § 1(7A).

Applied here, the judge should look to the combined condition diagnosed as gangrene of the toe and cellulitis of the foot and the domino of medical events culminating in death thereafter, which Dr. Menzoian found "related" to the injury, (Dec. 8), and specifically find whether the work injury remained "a major cause" of those conditions. And consistent with the language of the statute, even if diabetes and coronary artery disease were themselves also major or predominant causes of the employee's demise, if the judge finds the compensable injury remained "a major" cause of the medical cascade, the claimant could nonetheless prevail.

When looking at the progression of the medical disability the difficult question that the "remains" element of § 1(7A) raises is: when does the causal relation between the industrial injury and the incapacity begin and when, if ever, does it cease to be major? Its answer requires resort to the physician(s) opinions. At this point in the § 1(7A) assessment judges should return to the basics of incapacity adjudication. While the burden is always on the claimant to show entitlement to compensation, Sponatski's Case, 220 Mass. 526, 530 (1920), there must be expert medical opinion evidence on which to base any finding of a change in the extent of an employee's incapacity. See Mastrangelo v. Ametek Aerospace, 7 Mass. Workers' Comp. Rep. 184, 187 (1993) ("[t]he issue of whether the employee remained disabled . . . must be resolved primarily on the basis of expert medical evidence") (emphasis added); Hummer's Case, 317 Mass. 617, 622 (1945) (whether post-amputation causal relation continued between degenerating heart condition and industrial injury was question of fact for judge, based chiefly on medical testimony). Thus, to determine whether the resulting medical condition underlying the claimed incapacity remains a major cause, judges must comb the expert medical opinion(s) for indications of either continuity or change in the causal status. See Sevigny's Case, 337 Mass. 747, 749-750 (1958) (medical evidence must show causal relation, more likely than not, between industrial injury and death). See also Crowley's Case, 287 Mass. 367, 374-375 (1934) (where medical evidence indicated chain of causation doubtful due to independent intervening causes, incapacity no longer compensable).

In the case at bar, Dr. Menzoian unreservedly opined that "everything that happened to [the employee] subsequent to being admitted to [the] hospital was related to the gangrenous toe." (Dec. 8-9, Dep. 27.) See Gulczynski v. Granada Hospital Group, 7 Mass. Workers' comp. Rep. 151, 152 (1993). Moreover, although the doctor does not use the term, "major," anywhere in his opinion, it is the medical opinion in total not the presence or absence of any specific legal term that should govern whether his testimony supports a favorable finding under the § 1(7A) standard. But an opinion as to major must be in some way expressed in the record.

As stated earlier, the issue of causal nexus between incapacity and a work related injury is a question of fact and law for the judge. Scali v.Mara Products, Inc., 6 Mass. Workers' Comp. Rep. 78, 80 (1992), citingBrozozowski's Case, 328 Mass. 113 (1951). Causation in the instant case must be reached under the rubric of § 1(7A) as most recently amended. This was not done. Yet what was done seems irreconcilably inconsistent with the legal conclusions reached. Therefore, we must vacate the conclusions on causal relation as being arbitrary. G.L.c. 152, § 11C. On remand with the assistance of expert medical opinion(s), the judge must determine, whether the industrial accident (i.e. the trauma to the toe at work), combined with the pre-existing non-work diseases of diabetes and arteriosclerosis, to cause or prolong a disability or need for treatment. If she answers this in the affirmative, then she must also decide whether the compensable work injury "remained" a major cause of the resultant condition until the employee's death.

We remand the case for an application of a § 1(7A) analysis. The judge may adduce further evidence if necessary, to respond to the elements of § 1(7A) as they are presented here.

_________________________ Susan Maze-Rothstein Administrative Law Judge

_________________________ Edward P. Kirby Administrative Law Judge

Filed: March 14, 1996