OPINION
LOPEZ, Judge.This appeal involves the issue of which of two insurance carriers should pay compensation benefits to a disabled workman who suffered successive injuries while working for two different employers. The finding of the trial court that the workman is entitled to 100% disability is not contested by any party.
Claimant Powers is a bricklayer who, the trial court found, became disabled as the result of injuries incurred while working for two successive employers. The first accidental injury occurred on June 3, 1976, while Powers was working for Riccobene Masonry Construction (hereafter Riccobene). He stepped off a curb with a bag of mortar in his arms and experienced a severe back and leg pain which prevented him from working for two weeks. Riccobene’s insurance carrier paid Powers workmen’s compensation during this period. His injury was diagnosed by an orthopedic surgeon as acute lumbosacral muscular strain. Powers returned to work for Riccobene, and continued there until September 1977, except for an eleven week period during which he worked as a bricklayer somewhere else. In September 1977, he went to work as a bricklayer for Rufus Gillory Masonry (hereafter Gillory). After the 1976 injury, he continued to have intermittent back trouble and between June, 1976, and September 1978, he saw Dr. Moon, the orthopedic surgeon, three times. The diagnosis of lumbosacral strain remained the same. Powers took two weeks off work in October 1978, to rest his back. On January 29, 1979, he left work early because of intense back pain. The next day Dr. Moon found he had a herniated disc. Powers underwent surgery for this condition on February 14, 1979. He has not worked since January 29, 1979.
The trial court found that Powers suffered a first injury on June 3, 1976, while working for Riccobene, and a second injury, which it characterized as an “operative accident” between August, 1978 and January 29, 1979, while working for Gillory. It found that both the injury incurred while working for Riccobene and that incurred while working for Gillory were proximate causes of Powers’ disability, and apportioned the compensation payments between the insurance carriers of the two employers. The insurance companies appeal the apportionment. We find that, in the. circumstances and posture of this case, the second insurance company should pay the entire amount.
Transamerica Insurance Company, Gillory’s insurer, argues that (1) there was no second accidental injury arising out of and in the course of Powers’ employment with Gillory; (2) even if there had been such an injury, Gillory had no notice of it within thirty days as required by statute; and (3) even if the notice were proper, United States Fidelity & Guaranty Company, Riccobene’s insurer, should pay, because the second injury was the result of the first injury. For ease in description, we shall refer hereafter to the insurance companies by the name of the employer they represent.
Second Injury
The trial court found that:
Plaintiff’s present disability was proximately caused by the aggravation of the June 3, 1976 accident by an operative accident that Plaintiff suffered between August, 1978 and January 29, 1979 while working for Defendant Gilloryf.]
and Gillory challenges this finding. While an appellate court cannot make findings of its own, it can interpret those of the trial court to determine whether they are sufficient to support the judgment entered. Herndon v. Albuquerque Public Schools, 92 N.M. 635, 593 P.2d 470 (Ct.App.1978). We interpret the above finding to mean that while working for Gillory, Powers suffered a compensable injury as described in § 52-1-28, N.M.S.A. 1978 of the Workmen’s Compensation Act, §§ 52-1-1 to 52-1-69, N.M.S.A. 1978, and that this injury contributed to some extent to Powers’ disability.
Gillory asserts there is not sufficient evidence to establish that Powers suffered an injury while working for him because none of the experts who testified were able to pinpoint the time when the disc ruptured. While the evidence clearly supports the trial court’s finding that the rupture occurred sometime between August, 1978, and January 29, 1979, during which period Powers was working only for Gillory, it is not clear that the rupture occurred while Powers was at work, and the trial court did not so find.
Since 1970, the law in New Mexico has been that an internal malfunction of the body caused by on-the-job activity is a compensable injury under the Workmen’s Compensation Act. Lyon v. Catron County Commissioners, 81 N.M. 120, 464 P.2d 410 (Ct.App.1969), cert. denied, 81 N.M. 140, 464 P.2d 559 (1970). This court wrote:
[W]e take it that a malfunction of the body itself, such as a fracture of the disc or tearing a ligament or blood vessel, caused or accelerated by doing work required or expected in employment is an accidental injury within the meaning and intent of the compensation act.
Id. at 125, 464 P.2d at 415. In Lyon, the evidence indicated that the disc actually did rupture while the claimant was working. This need not be the case, however. It is not necessary that the evidence of a body malfunction or accidental injury develop while the claimant is working. In Webb v. New Mexico Pub. Co., 47 N.M. 279, 141 P.2d 333 (1943), the New Mexico Supreme Court found that a workman who developed a rash on his hands from washing with a soap used frequently in the course of his employment was entitled to compensation benefits. No evidence was mentioned which would show that the rash actually appeared while the claimant was working.
It is not necessary for Powers to prove that the disc ruptured while he was working, as long as he is able to prove that his labor caused or accelerated the physical malfunction. In Herndon, this court found the date a claimant quit work due to the severity of her back pain was the date that she suffered an accidental injury. Although in that case there was a specific accident at an earlier date when the claimant fell down a ramp with a cart of books, this incident was not crucial in our reasoning there. The woman had had a history of back trouble before the cart incident, and we reasoned that her daily job, which involved lifting and carrying books, was the cause of her eventual disability. We wrote:
[I]f the stress of labor aggravates or accelerates the development of a pre-existing infirmity causing an internal breakdown of that part of the structure, a personal injury by accident does occur.
Id. at 640, 593 P.2d at 475. We interpret the trial court’s finding in the instant ease, in light of Herndon, to be that Powers suffered an accidental injury on January 29, 1979, while working for Gillory.
Notice
Section 52-1-29, N.M.S.A. 1978 of the Workmen’s Compensation Act requires that the employer have either written or actual notice of the accident within thirty days of its occurrence. Gillory did not receive written notice of the January 29 accidental injury, but the trial court found that he had actual notice of it. Gillory asserts this finding is not supported by the evidence.
On appeal, the court reviewing a workmen’s compensation case will consider the evidence, along with all reasonable inferences which may be drawn from it, in the light most favorable to support the findings of the trial court. Moorhead v. Gray Ranch Co., 90 N.M. 220, 561 P.2d 493 (Ct.App.), cert. denied, 90 N.M. 254, 561 P.2d 1347 (1977). Only favorable evidence will be considered. Marez v. Kerr-McGee Nuclear Corp., 93 N.M. 9, 595 P.2d 1204 (Ct.App.1978), cert. denied, 92 N.M. 532, 591 P.2d 286 (1979). The determination of whether the employer had actual knowledge is made from a consideration of the totality of the facts and circumstances. Rohrer v. Eidal International, 79 N.M. 711, 449 P.2d 81 (Ct.App.1968).
Gillory knew that Powers had hurt his back while working for Riccobene, that his back still hurt, and that Powers’ condition was gradually worsening. He knew that in October 1978 Powers took two weeks off to rest his back and to prepare himself for a big apartment job of Gillory’s. On January 29, 1979, the day Powers left work, he was working on a kiva-like fireplace. Gillory knew that lifting and building kiva fireplaces was especially hard on Powers’ back. On January 30, 1979, Powers told Gillory that he had to see a doctor about his back. Gillory knew that he was in pain, and he drove Powers to the place his wife worked so that she could take him to a doctor. Gillory knew that Powers had surgery on his back. Shortly thereafter, one of his employees filled out a first report of accident form for Powers. The filing of an accident report by an employer may be interpreted by the courts as an acknowledgment of notice of the accident and injury. See, Waymire v. Signal Oil Field Service, Inc., 77 N.M. 297, 422 P.2d 34 (1966); Herndon. Considering the totality of the circumstances the trial court could properly find that Gillory had actual notice of Powers’ accidental injury.
The notice was timely. The time for giving notice begins to run when an employee knows, or by the exercise of reasonable diligence should know, that he has sustained an accidental injury. Bell v. Kenneth P. Thompson Co., 76 N.M. 420, 415 P.2d 546 (1966). In that Powers’ injury while working for Gillory resulted from an internal degeneration of a body part rather than an external incident, he could not have been expected to give notice until after the injury manifested itself on January 29, 1979. The cases cited by Gillory, Hammond v. Kersey, 83 N.M. 430, 492 P.2d 1293 (Ct.App.1972) and Bell, where the courts found there was no notice when the employer was not informed of the date the accident occurred, are not applicable. The disabilities involved in those cases were claimed as the result of specific external accidental incidents, and not, as here, as the result of an internal body malfunction. Within thirty days, Gillory knew as much as Powers himself did about the accidental injury of January 29, 1979.
Liability of Second Insurer
There are two rules generally used in determining which of two insurance companies is liable in second injury cases. One rule, frequently referred to as the Massachusetts-Michigan rule, see generally, 4 Larson, Workmen’s Compensation Law §§ 95.12 and 95.31 (1980), is that the second insurer is liable if the second injury contributed even slightly to the cause of the disability. Rock’s Case, 323 Mass. 428, 82 N.E.2d 616 (1948). The other rule, known as the Florida rule, Hanks v. Walker, 60 N.M. 166, 288 P.2d 699 (1955), is that the insurance company covering the risk at the time of the first injury pays if the second injury is the result of the first injury from which the workman has never recovered, and is a manifestation of the continuance of that injury. Brewer v. Pan American Airways, Inc., 156 Fla. 812, 24 So.2d 521 (1946). Both rules have been cited with approval in New Mexico. See, Hanks; Perea v. Gorby, 94 N.M. 325, 610 P.2d 212 (Ct.App.1980); Ponce v. Hanes L’Eggs Products, Inc., 91 N.M. 112, 570 P.2d 943 (Ct.App.1977). A third alternative, used in some states, is apportionment. 4 Larson, Workmen’s Compensation Law §§ 95.00 and 95.31 (1980); 16 Willamette L.Rev. 137 (1979). Apportionment has not been used in New Mexico. The Legislature has not enacted a statute allowing it, and the issue of whether it should be used, absent a statute, has not been before this court before. The desire to treat both insurance companies equitably is the principle behind apportionment. See, Anderson v. Babcock & Wilcox Co., 256 N.Y. 146, 175 N.E. 654 (Ct.App.1931). Some states have rejected judicial apportionment on the grounds that the percentage liabilities would be mere speculation, Baxter v. Smith, 211 Tenn. 347, 364 S.W.2d 936 (1962), and that the decision to allow apportionment should be made by the legislature and not the courts. Johnnie’s Produce Co. v. Benedict & Jordan, 120 So.2d 12 (Fla.1960); Baxter. To these objections could be added the one that apportionment could lead to increased litigation between insurance companies which in turn might result, as it did in this case before us, in a delay in paying the workman the benefits to which he is justly entitled while the insurance companies fight over the percentage amount each is to pay. While in each individual case it might not be entirely fair that one company should bear the entire burden, in the long run each company will likely insure as many first employers as second employers, and its respective liability will even out.
In the present case, the trial court found that the injury suffered while Powers was working for Gillory was a proximate cause of his disability. Gillory argues that there is insufficient evidence to support this finding of proximate cause. In support of this contention, he cites Dr. Moon’s testimony that Powers’ lifestyle was the cause of his problem.
Considering the evidence along with all reasonable inferences which may be drawn from it in the light most favorable to support the findings of the trial court, Moorhead, and disregarding unfavorable evidence, Marez, we cannot agree that the finding is in error. Besides the testimony referred to above, Dr. Moon also testifies that there was a direct relation between Powers’ work and his present condition, and that this work contributed to the protrusion of the disc. He said in his deposition that the continued work as a rock mason was one of the causes of the progression of Powers’ back condition. Considered in a favorable light, the evidence which supports the trial court’s finding of causal disability is substantial. Substantial evidence is relevant evidence which a reasonable mind accepts as adequate to support the conclusion. Id. The findings of the trial court in a workman’s compensation case will not be disturbed on appeal if they are supported by substantial evidence. Id. Since there is substantial evidence to support the trial court’s finding that the accidental injury sustained while working for Gillory was the proximate cause of Powers’ disability, we will not disturb this finding.
Gillory contends that Perea is controlling and requires that the first employer be held liable. We disagree. In that case we allowed a workman who suffered two injuries while working for two different employers to sue his first employer for compensation benefits. The second employer was a business located in California. The issue in that case was not, as between two insurance companies, which one should pay, but whether the first insurance company could be held liable. The second employer was not a party to the suit.
The judgment is affirmed, excepting that portion of it which apportions the compensation benefits between the two employers and their respective insurance companies. The trial court is ordered to enter a judgment against Rufus Gillory Masonry Company and Transamerica Insurance Company for the entire amount. Plaintiff is awarded $1,500 for attorney’s fees on this appeal.
IT IS SO ORDERED.
WALTERS, J., concurs. SUTIN, J., dissents.