Filed 6/22/17
                CERTIFIED FOR PUBLICATION




IN THE COURT OF APPEAL OF THE STATE OF CALIFORNIA

                SECOND APPELLATE DISTRICT

                      DIVISION FOUR


MAUREEN HIKIDA,                       B279412

       Petitioner,                    (W.C.A.B. No. ADJ7721810)

       v.

WORKERS’ COMPENSATION
APPEALS BOARD, COSTCO
WHOLESALE CORPORATION et
al.,

       Respondents.


      PROCEEDINGS to review a decision of the Workers’
Compensation Appeals Board. Annulled and remanded with
directions.
      Law Firm of Rowen, Gurvey & Win and Alan Z. Gurvey
for Petitioner.
      Law Office of Mark Gearhert and Justin C. Sonnicksen
for California Applicants’ Attorneys Association as Amicus
Curiae on behalf of Petitioner.
      Mullen & Filippi, Jay S. Cohen and Daniel Nachison;
Seyfarth & Shaw and Kiran A. Seldon for Respondents
Costco Wholesale Corporation and Helmsman Management
Services.
      John F. Shields and Peter Ray for Respondent
Workers’ Compensation Appeals Board.

            _____________________________________

      Petitioner Maureen Hikida seeks review of an order of
respondent Workers’ Compensation Appeals Board (the
Board) affirming the decision of the workers’ compensation
judge (WCJ) to apportion the permanent total disability
suffered by petitioner between industrial and nonindustrial
causes prior to issuing its award. Petitioner contends that
because the agreed medical examiner (AME) concluded her
permanent total disability was the result of a failed surgery
for carpal tunnel syndrome, a condition she contracted
primarily due to the clerical work she performed for
respondent Costco Wholesale Corporation (Costco) for more
than 25 years, apportionment was not appropriate.1 After

1     Costco is adjusted by respondent Helmsman Management
Services (Helmsman). We granted permission to California
Applicants’ Attorneys Association to file an amicus curiae brief in
support of petitioner.




                                 2
briefing on the merits was complete, respondents filed a
supplemental brief raising a “question” as to this court’s
jurisdiction. Specifically, respondents suggested the writ
petition might have been untimely, because the issue of
apportionment was resolved by the Board months before the
Board denied reconsideration of the WCJ’s final award. We
conclude the petition was timely filed. We further conclude
that despite significant changes in the law governing
workers’ compensation in 2004, disability resulting from
medical treatment for which the employer is responsible is
not subject to apportionment. Accordingly, we annul the
Board’s order and remand for an increase in petitioner’s
disability award.

   FACTUAL AND PROCEDURAL BACKGROUND
     Petitioner was employed by respondent Costco from
November 1984 to May 2010. During this period, she
developed a number of medical conditions, including carpel
tunnel syndrome.2


2      Pursuant to stipulation of the parties, the WCJ found that
petitioner “sustained injury arising out of and in the course of
employment to her cervical spine, thoracic spine, upper
extremities, . . . psyche, fingers, [and] elbows . . . .” He further
found that she suffered from employment-related headaches,
memory loss, sleep disorder, and “deconditioning.” Petitioner
claimed to have other medical conditions, including hypertension
and irritable bowel syndrome, but the WCJ did not find them
employment related.




                                 3
In May 2010, she took leave from work to undergo carpel
tunnel surgery.3 Following the surgery, she developed
chronic regional pain syndrome (CRPS), a condition that
caused her debilitating pain in her upper extremities and
severely impaired her ability to function. She never
returned to work. The parties stipulated she became
permanent and stationary on May 2, 2013.
      In 2012 and 2013, petitioner was examined by an AME
in orthopedics, Chester Hasday, M.D. Dr. Hasday found
petitioner permanently and totally disabled from the labor
market. He found that her permanent total disability was
due entirely to the effects of the CRPS that she developed as
a result of the failed carpal tunnel surgery. He further
concluded that petitioner’s carpal tunnel condition itself was
90 percent due to industrial factors and 10 percent to
nonindustrial factors.4
      In issuing the award, the WCJ found that petitioner’s
permanent total disability was 90 percent due to industrial
factors, “after adjustment for apportionment.” Petitioner
sought reconsideration by the Board, contending her

3     Medical reports indicate petitioner was considered
temporarily totally disabled at this time. Medical treatment was
provided under the auspices of workers’ compensation law. (See
Labor Code, § 4600.) (Undesignated statutory references are to
the Labor Code.)
4     Petitioner was also evaluated by a vocational expert who
found her permanently and totally disabled, without access to
any occupation in the open labor market.




                                4
disability was 100 percent industrial because it derived from
medical treatment, entitling her to an unapportioned award.
The WCJ prepared a report and recommendation, in which
he recommended denying the petition for reconsideration,
stating that he was “obligated under Labor Code section
4663 to address apportionment of permanent disability to
factors other than applicant’s industrial injury.”
      On February 8, 2016, in a two-to-one decision, the
Board affirmed the apportionment. The majority concluded:
“To properly evaluate the issue of apportionment of
permanent disability, it is necessary to ‘parcel out’ the
causative sources of the permanent disability, nonindustrial,
prior industrial and current industrial, and ‘decide the
amount directly caused by the current industrial source.’
[Citation.] [¶] As the WCJ notes in the Report, the AME
Dr. Hasday concluded that [petitioner’s] CRPS caused her to
be totally permanently disabled. However, there is a basis
for apportionment of that permanent disability to
nonindustrial causative sources as found by the WCJ
because the CRPS was caused by the surgery to treat
[petitioner’s] carpal tunnel condition, which is 10 percent
nonindustrial and 90 percent industrial as opined by Dr.
Hasday. [Citation.]” (Quoting Brodie v. Workers. Comp.
Appeals Bd. (2007) 40 Cal.4th 1313, 1328 (Brodie).) The
Board nonetheless granted the petition for reconsideration,
finding the WCJ had failed to take into account medical
reports showing petitioner suffered employment-related
psychiatric injuries that “need[] to be taken into account




                              5
along with the other industrial causative sources in
determining the level of compensable permanent disability
resulting from the industrial injury.”
      The dissent, citing multiple cases holding that an
employee is entitled to compensation for new or aggravated
injury resulting from the medical or surgical treatment of an
industrial injury, stated the WCJ erred “because he
apportioned the permanent disability caused by [petitioner’s]
CRPS based upon the causation of [her] underlying carpal
tunnel injury and not upon the cause of her permanent
disability . . . . In that the CRPS causing [petitioner’s] total
permanent disability resulted entirely from the surgery
reasonably performed to treat [her] industrial carpal tunnel
injury, it is error to apportion the permanent disability
resulting from that medical treatment based upon the causes
of the injury that was being treated.” (Italics omitted.)
      After the Board issued its February 2016 decision
remanding the case, petitioner prepared a trial brief urging
the WCJ to find her 100 percent disabled based on the
psychiatric injury, which she alleged was entirely industrial.
Petitioner further contended that the vocational expert’s
opinion supported a 100 percent award, and that a 100
percent award was required under section 4662, subdivision
(b) due to her inability to fully use her arms and hands.5

5      Section 4662, subdivision (a) provides: “Any of the
following permanent disabilities shall be conclusively presumed
to be total in character: . . . (2) Loss of both hands or the use
thereof.”




                                 6
The WCJ increased petitioner’s disability award to 98
percent after apportionment. Following issuance of the
amended award, petitioner filed a second petition for
reconsideration seeking increase in the award on a number
of grounds, including the vocational expert’s opinion and
section 4662. She also asked the Board to revisit the
appropriateness of apportionment. By order dated October
25, 2016, the Board again denied reconsideration, finding
apportionment appropriate in a two-to-one decision for the
reasons previously stated. The writ petition seeking review
of the Board’s decision was filed December 9, 2016.6




6      Respondents Costco and Helmsman filed an answer. The
Board submitted a letter to the court stating it would not answer
the petition because “the decisions of the [WCJ] and the Appeals
Board provide the reasons and record for the [Board’s] decision in
this case . . . .” The letter stated: “When the Appeals Board
denied reconsideration of the WCJ’s August 3, 2016 Decision on
October 25, 2016, the August 3, 2016 Decision of the WCJ became
the final decision of the [Board] in this case for purposes of
appellate review.”




                                7
                         DISCUSSION
      A. Timeliness of Appeal
      Shortly before oral argument, respondents Costco and
Helmsman filed a supplemental brief contending the Board’s
February 8, 2016 opinion was “likely” the “final decision”
with respect to the apportionment issue, and that the appeal
should be dismissed as untimely. For the reasons set forth
below, we disagree.
      Section 5950 provides that “[a]ny person affected by an
order, decision, or award of the [Board] may . . . apply to the
Supreme Court or to the court of appeal for the appellate
district in which he resides, for a writ of review . . . .” The
petition for writ of review must be filed “within 45 days after
a petition for reconsideration is denied, or, if a petition is
granted or reconsideration is had on the appeal board’s own
motion, within 45 days after the filing of the order, decision,
or award following reconsideration.” (§ 5950.) “The failure
of an aggrieved party to seek judicial review of a final order
of the [Board] bars later challenge to the propriety of the
order or decision before either the [Board] or the court.”
(State Farm General Ins. Co. v. Workers’ Comp. Appeals Bd.
(2013) 218 Cal.App.4th 258, 261.)
      Generally, an appeal will not lie to review an order
made by the Board where the order remands the matter for
a further hearing, leaving issues to be resolved by the WCJ.
(Gumilla v. Industrial Acc. Comm. (1921) 187 Cal. 638, 639-
640; Safeway Stores, Inc. v. Workers’ Comp. Appeals Bd.
(1980) 104 Cal.App.3d 528, 533 (Safeway Stores).) “Allowing




                               8
parties to utilize the appellate process on individual issues
in a single compensation claim could create a danger of
defeating [the California] constitutional objective” of
administering the workers’ compensation laws to “accom-
plish justice in all cases ‘expeditiously, inexpensively, and
without incumbrance . . . .’” (Safeway Stores, supra, at
p. 533, italics omitted; see Maranian v. Workers’ Comp.
Appeals Bd. (2000) 81 Cal.App.4th 1068, 1073 (Maranian)
[“The well-known final judgment rule that governs general
civil appeals was designed to prevent costly piecemeal
dispositions and multiple reviews which burden the courts
and impede the judicial process”].) At the same time, courts
have recognized that permitting early appellate review to
resolve certain “threshold issues” may enhance rather than
detract from the expeditious resolution of workers’
compensation claims. (Safeway Stores, supra, at p. 533;
Maranian, supra, at p. 1078.)
       In general, a threshold issue is one “crucial to the
employee’s right to receive benefits.” (Maranian, supra, 81
Cal.App.4th at p. 1078; see 2 Hanna, Cal. Law of Employee
Injuries and Workers’ Compensation (2d rev. ed. 2007)
§ 28.04, p. 28-11 [“A threshold issue is an issue that is basic
to the establishment of the employee’s rights to benefits,
such as the territorial jurisdiction of the Board, the existence
of the employment relationship, and statute of limitations
issues” (fn. omitted)].) The fact that an issue is significant or
important to the litigation is not sufficient to support a
finding that it is a threshold issue. As the court stated in




                                9
Ogden Entertainment Services v. Workers’ Comp. Appeals
Bd. (2014) 233 Cal.App.4th 970, 986, 987 although the
determination “[w]hether the [worker’s] psychiatric injury
was industrial” was “one of the principal issues” before the
Board, “[t]he disposition by the appeals board of one of
several issues on the merits is not a final decision of the
appeals board”; “[i]t is only a final order, decision or award of
the appeals board that is reviewable by this court by way of
a petition for a writ of review.”7


7      In Safeway Stores, the court agreed to decide whether the
worker’s injury arose out of and in the course of employment.
(Safeway Stores, supra, 104 Cal.App.3d at p. 533.) Since then,
courts have defined “threshold issue[]” to include whether
California workers’ compensation law applied to a professional
athlete who played a single game in California (Federal
Insurance Co. v. W.C.A.B. (Johnson) (2013) 221 Cal.App.4th
1116, 1119-1122); whether an employer failed to reject the
worker’s claim within the requisite statutory period (Maranian,
supra, 81 Cal.App.4th at pp. 1080-1081); and whether a worker of
less than six months was barred from recovering compensation
benefits for a claimed psychological injury (Wal-Mart Stores, Inc.
v. Workers’ Comp. Appeals Bd. (2003) 112 Cal.App.4th 1435,
1438, fn. 3 (Wal-Mart Stores)). Courts have found that the
determination whether a psychiatric injury is industrial is not a
threshold issue (Ogden Entertainment Services v. Workers’ Comp.
Appeals Bd., supra, 233 Cal.App.4th at pp. 986-987), and that an
order denying a petition to strike a physician’s report and remove
her as an AME is not a threshold issue (Capital Builders
Hardware, Inc. v. Workers’ Comp. Appeals Bd. (Gaona) (2016) 5
Cal.App.5th 658, 662).




                                10
      The Board’s February 2016 decision was not a final
order disposing of the case, as it remanded the matter to the
WCJ to determine the amount of compensation to be
awarded for the psychiatric disability and other issues raised
by petitioner. Nor was the Board’s decision on
apportionment a threshold issue, “crucial to [petitioner’s]
right to receive benefits.” (Maranian, supra, 81 Cal.App.4th
at p. 1078.) Petitioner was entitled to benefits regardless of
apportionment, and respondents essentially conceded
petitioner’s disability was at least 90 percent the result of
industrial factors. On remand to the WCJ, petitioner
advanced multiple theories to warrant a 100 percent award
without regard to apportionment. By maximizing her award
in the workers’ compensation proceedings before resorting to
the courts, petitioner was following a path that could have
led to an expeditious resolution of the proceeding without
the need for appellate review. We discern no reason an
applicant should be compelled to seek immediate writ review
of an issue that may not be dispositive of his or her award.
In short, we conclude petitioner’s pursuit of her claim to its
conclusion, in lieu of seeking review of the Board’s February
2016 decision, did not represent disregard of a final order.
Accordingly, we deny respondent’s request for dismissal.8

8    We observe that in the authorities relied on by
respondents, the courts saved an otherwise premature appeal by
deeming the issue involved a “threshold issue.” (Safeway Stores,
supra, 104 Cal.App.3d at pp. 531, 535; Maranian, supra, 81
Cal.App.4th at p. 1070; Wal-Mart Stores, supra, 112 Cal.App.4th
(Fn. continued on the next page.)




                                    11
      B. Merits
      We turn now to the merits of petitioner’s assertion that
the Board erred when it found that despite the AME’s
unchallenged opinion that petitioner’s CRPS resulting from
the failed surgery rendered her totally disabled, the Board
deemed her permanent total disability to be 90 percent due
to industrial factors after apportionment.
      The Board’s conclusions on questions of law are
reviewed de novo. (Benson v. Workers’ Comp. Appeals Bd.
(2009) 170 Cal.App.4th 1535, 1543.) Its findings on
questions of fact “are conclusive and final so long as, based
on the entire record, they are supported by substantial
evidence.” (Save Mart Stores v. Workers’ Comp. Appeals Bd.
(1992) 3 Cal.App.4th 720, 723.) When the reviewing court is
asked to interpret and apply a statute to undisputed facts,
the review is de novo. (Benson, supra, at p. 1543.)


at p. 1438, fn. 3; Kosowski v. Workers’ Comp. Appeals Bd. (1985)
170 Cal.App.3d 632, 636; Duncan v. Workers’ Comp. Appeals Bd.
(2008) 166 Cal.App.4th 294, 299; see also Matea v. Workers’
Comp. Appeals Bd. (2006) 144 Cal.App.4th 1435, 1442, fn. 3;
Kopping v. Workers’ Comp. Appeals Bd. (2006) 142 Cal.App.4th
1099, 1105, fn. 6.) Respondents have not cited -- and we have not
found -- a case in which an appellate court has dismissed an
applicant’s petition for review because an earlier Board order
remanding a case for further proceedings was determined to have
resolved a threshold issue. Courts should be cautious in finding a
“threshold issue” where such finding will deprive a party of the
right to an appeal.




                               12
            1. Changes in the Law of Apportionment
      “‘Apportionment is the process employed by the Board
to segregate the residual[] [effects] of an industrial injury
from those attributable to other industrial injuries, or to
nonindustrial factors, in order to fairly allocate the legal
responsibility.’” (Brodie, supra, 40 Cal.4th at p. 1321.) Prior
to 2004, apportionment was “closely circumscribed.” (Id. at
p. 1326.) Former section 4663, governing apportionment
where an industrial injury aggravated a preexisting
nonindustrial condition leading to disability, was interpreted
as permitting apportionment “‘only if the [B]oard f[ound]
that part of the disability would have resulted from the
normal progress of the underlying nonindustrial disease.’”9
(Brodie, supra, at p. 1326; see Gay v. Workers’ Comp.
Appeals Bd. (1979) 96 Cal.App.3d 555, 562 [“[T]o support
apportionment of nonindustrial disability under [former]
section 4663, there must be medical evidence expressly
stating that the apportioned disability is the result of the
natural progression of the preexisting nonindustrial
condition and such nonindustrial disability would have
occurred even in absence of the industrial injury”].) This
rule was said to flow from the principle that an employer

9     Former section 4663 provided: “In case of aggravation of
any disease existing prior to a compensable injury, compensation
shall be allowed only for the proportion of the disability due to
the aggravation of such prior disease which is reasonably
attributed to the injury.” (Stats. 1937, ch. 90, § 4663, p. 284.)




                               13
“takes the employee as he finds him at the time of the
employment” (Ballard v. Workmen’s Comp. App. Bd. (1971) 3
Cal.3d 832, 837), and that an employee could not be denied
compensation “merely because his physical condition was
such that he sustained a disability which a person of
stronger constitution or in better health would not have
suffered.” (Duthie v. Workers’ Comp. Appeals Bd. (1978) 86
Cal.App.3d 721, 727.) The rule “left employers liable for any
portion of a disability that would not have occurred but for
the current industrial cause; if the disability arose in part
from an interaction between an industrial cause and a
nonindustrial cause, but the nonindustrial cause would not
alone have given rise to a disability, no apportionment was
to be allowed.” (Brodie, supra, at p. 1326.) “[S]o long as the
industrial cause was a but-for proximate cause of the
disability, the employer w[as] liable for the entire disability,
without apportionment.” (Ibid.; see, e.g., Franklin v.
Workers’ Comp. Appeals Bd. (1978) 79 Cal.App.3d 224, 247
[where employee with history of high cholesterol and
arteriosclerosis suffered heart attack while working, no
apportionment was required for disability attributable to
heart attack “because industrial factors aggravated the
heart disease and accelerated the occurrence of the infarct,
which absent the industrial exposure would not have
occurred when it did”].)
      In addition, prior to 2004, former section 4750 -- which
governed apportionment between a current and past
industrial injury -- was interpreted as allowing the employee




                               14
to defeat apportionment by establishing rehabilitation of an
injury for which a permanent disability award had already
been issued.10 (See, e.g., Robinson v. Workers’ Comp.
Appeals Bd. (1981) 114 Cal.App.3d 593, 602 [“[T]he fact that
a worker received a permanent disability rating for his
earlier injury, and was in fact partially disabled for some
period of time, does not provide a basis for apportion-
ment. . . . ‘[I]f an injured employee recovers and thereafter
is again injured, he is entitled to compensation for the injury
to his rehabilitated condition, not limited in amount by the
terms of a former award’”]; National Auto. & Cas. Ins. Co. v.
Industrial Acc. Com. (1963) 216 Cal.App.2d 204, 211 [worker
who had been found 65 percent disabled after suffering first
back injury and 78 percent after suffering second back injury
entitled to 39 percent award where evidence established “a
substantial improvement of his bodily condition in the period
of time which elapsed prior to the second injury”]; see id., at
pp. 206-211.)

10    Former section 4750 provided: “An employee who is
suffering from a previous permanent disability or physical
impairment and sustains permanent injury thereafter shall not
receive from the employer compensation for the later injury in
excess of the compensation allowed for such injury when
considered by itself and not in conjunction with or in relation to
the previous disability or impairment. [¶] The employer shall
not be liable for compensation to such an employee for the
combined disability, but only for that portion due to the later
injury as though no prior disability or impairment had existed.”
(Stats. 1945, ch. 1161, § 1, p. 2209.)




                                 15
      As the Supreme Court explained in Brodie, reversing
these constraints on apportionment was a key goal of the
Legislature when it amended the governing statutes in 2004,
eliminating section 4750, re-writing section 4663 and adding
section 4664:11 “The plain language of new sections 4663
and 4664 demonstrates they were intended to reverse these
features of former section 4663 and 4750. [Citation.] . . .

11    Section 4663 currently provides that “[a]pportionment of
permanent disability shall be based on causation” and “[a]
physician who prepares a report addressing the issue of
permanent disability due to a claimed industrial injury shall
address in that report the issue of causation of the permanent
disability” which “must include an apportionment determination”
stating “what approximate percentage of the permanent
disability was caused by the direct result of injury arising out of
and occurring in the course of employment and what approximate
percentage of the permanent disability was caused by other
factors both before and subsequent to the industrial injury,
including prior industrial injuries.”
       Section 4664 provides: “(a) The employer shall only be
liable for the percentage of permanent disability directly caused
by the injury arising out of and occurring in the course of
employment. [¶] (b) If the applicant has received a prior award of
permanent disability, it shall be conclusively presumed that the
prior permanent disability exists at the time of any subsequent
industrial injury. This presumption is a presumption affecting
the burden of proof. [¶] (c)(1) The accumulation of all permanent
disability awards issued with respect to any one region of the
body in favor of one individual employee shall not exceed 100
percent over the employee’s lifetime unless the employee’s injury
or illness is conclusively presumed to be total in character
pursuant to Section 4662. . . . ”




                                16
[N]ew sections 4663, subdivision (a) and 4664, subdivision
(a) eliminate the bar against apportionment based on
pathology and asymptomatic causes [citations], while section
4664, subdivision (b) was intended to reverse the rule based
on former section 4750 that permitted an injured employee
to show rehabilitation of an injury for which a permanent
disability award had already been issued [citations].”
(Brodie, supra, 40 Cal.4th at pp. 1327, 1328.) In other
words, the amendments were intended to usher in a “new
regime of apportionment based on causation,” and a “new
approach to apportionment” that “look[s] at the current
disability and parcel[s] out its causative sources --
nonindustrial, prior industrial, current industrial -- and
decide[s] the amount directly caused by the current
industrial source.” (Id. at p. 1328.)12




12     The Board had come to a similar conclusion in Escobedo v.
Marshalls (2005) 70 Cal.Comp.Cases 604, in which it stated:
“[I]n [enacting the 2004 changes], . . . the Legislature intended to
expand . . . the scope of legally permissible apportionment. . . .
[S]ection 4663(c) provides for apportionment based on ‘what
approximate percentage of the permanent disability was caused
by other factors both before and subsequent to the industrial
injury, including prior industrial injuries.’ . . . [T]his language
appears to reflect a legislative intent to enlarge the range of
factors that may be considered in determining the cause of
permanent disability . . . .” (Id. at pp. 616-617, italics omitted.)




                                 17
            2. Disability Caused by Medical Treatment of an
              Industrial Injury
      Under the changes wrought by the 2004 amendments,
the disability arising from petitioner’s carpal tunnel
syndrome was apportionable between industrial and
nonindustrial causes. However, petitioner’s permanent total
disability was caused not by her carpal tunnel condition, but
by the CRPS resulting from the medical treatment her
employer provided. The issue presented is whether an
employer is responsible for both the medical treatment and
any disability arising directly from unsuccessful medical
intervention, without apportionment. For the reasons
discussed below, we conclude it is.13

13    Petitioner and amicus curiae contend this issue has been
resolved, citing County of Sacramento v. WCAB (Chimeri) (2010)
75 Cal.Comp.Cases 159, Nilsen v. Vista Ford (Oct. 26, 2012,
W.C.A.B. No. ADJ630145) 2012 Cal. Wrk. Comp. P.D. LEXIS
528, Moran v. Dept. of Youth Authority (Jan. 21, 2011, W.C.A.B.
Nos. ADJ2192153, ADJ710643) 2011 Cal. Wrk. Comp. P.D. Lexis
43, and Steinkamp v. City of Concord (Mar. 30, 2006, W.C.A.B.
Nos. OAK 316754, WCK 0028639, WCK 0031066, WCK 0050335)
2006 Cal. Wrk. Comp. P.D. LEXIS 24. In Chimeri, the employee
became disabled after breaking his foot at work, which led him to
suffer CRPS and become addicted to pain medication. The
permanent total disability there was 100 percent work related.
In Nilsen, the employee similarly suffered a serious injury at
work leading to CRPS and dependency on pain medication. The
defendant sought to attribute some of the disability to the
employee’s pre-existing back condition, but the Board found no
evidence that his preexisting back condition had contributed to
his disability. In Moran, the employee suffered two injuries at
(Fn. continued on the next page.)




                                    18
      Section 4600 requires the employer to provide medical
treatment “reasonably required to cure or relieve the injured
worker from the effects of his or her injury . . . .” (See also
§ 4601 [stating that treatment by consulting physician and
certain other medical providers requested by the employee
“shall be at the expense of the employer”].) Although the


work, and the issue was whether apportionment between the
prior injury and the current injury was warranted. The Board
found the defendant had failed to meet its burden of proving the
prior injury overlapped the current one. Of the cited cases, only
Steinkamp addressed the issue squarely. There, the employee’s
cumulative knee injury was the result of various factors, some
industrial and some not. He underwent knee surgery, which led
to permanent disability. The Board concluded apportionment
was not warranted because “medical treatment is not
apportionable.” However, Steinkamp was not designated a
significant panel decision and its precedential value is limited.
      Petitioner further contends this matter was resolved in
Escobedo v. Marshalls, in which the Board stated: “Section
4663(a)’s statement that the apportionment of permanent
disability shall be based on ‘causation’ refers to the causation of
the permanent disability, not causation of the injury, and the
analysis of the causal factors of permanent disability for purposes
of apportionment may be different from the analysis of the causal
factors of the injury itself.” (Escobedo v. Marshalls, supra, 70
Cal.Comp.Cases at p. 607.) In Escobedo, the employee’s disability
was not the result of medical treatment. The Board addressed
apportionment where the disability was caused 50 percent by an
industrial injury and 50 percent by a preexisting degenerative
condition. “‘[A]n opinion is not authority for a proposition not
therein considered.’” (Westly v. Board of Administration (2003)
105 Cal.App.4th 1095, 1112.)




                                19
wording of this provision has changed over the years, it
consistently has been interpreted to require the employer to
pay for all medical treatment “[o]nce it has been established
that an industrial injury contributed to an employee’s need
for [it] . . . .” (Rouseyrol v. Workers’ Comp. App. Bd. (1991)
234 Cal.App.3d 1476, 1485; accord, Granado v. Workmen’s
Comp. App. Bd. (1968) 69 Cal.2d 399, 405-406 (Granado);
Sanchez v. Brooke (2012) 204 Cal.App.4th 126, 140-141;
Boehm & Associates v. Workers’ Comp. Appeals Bd. (2003)
108 Cal.App.4th 137, 142; Buhlert Trucking v. Workers’
Comp. Appeals Bd. (1988) 199 Cal.App.3d 1530, 1532;
Deauville v. Hall (1961) 188 Cal.App.2d 535, 540-541.)
       In Granado, the Supreme Court provided the following
rationale for its conclusion that “medical expense is not
apportionable”: “If medical expense reasonably necessary to
relieve from the industrial injury were apportionable, a
workingman, who is disabled, may not be able to pay his
share of the expense and thus forego treatment. Moreover,
the uncertainties attendant to the determination of the
proper apportionment might cause employers to refuse to
pay their share until there has been a hearing and decision
on the question of apportionment, and such delay in
payment may compel the injured workingman to forego the
prompt treatment to which he is entitled.” (Granado, supra,
69 Cal.2d at pp. 405-406.)
       It also has long been the rule that “the aggravation of
an industrial injury or the infliction of a new injury resulting
from its treatment or examination are compensable under




                               20
the provisions of the Workmen’s Compensation Act and,
therefore, within the exclusive cognizance of the Industrial
Accident Commission.”14 (Fitzpatrick v. Fidelity & Casualty
Co. of New York (1936) 7 Cal.2d 230, 232; accord, Nelson v.
Associated Indem. Corp. (1937) 19 Cal.App.2d 564, 566.)
Aggravation of the original industrial injury by medical
treatment is considered “a foreseeable consequence of the
original compensable injury, compensable within the
workers’ compensation proceeding and not the proper subject
of an independent common law damage proceeding against
the employer.” (National v. Certainteed Corp. (1978) 84
Cal.App.3d 813, 817.) Accordingly, “an employee is entitled
to compensation for a new or aggravated injury which
results from the medical or surgical treatment of an
industrial injury, whether the doctor was furnished by the
employer, his insurance carrier, or was selected by the
employee.” (Fitzpatrick v. Fidelity & Casualty Co. of New
York, supra, at pp. 233-234.)
      In Deuville v. Hall, supra, 188 Cal.App.2d 535, the
court explained that depriving the employee of compensation
for aggravation of an industrial injury resulting from
negligent medical treatment could lead to “an action in a
court of law against an employer for the latter’s negligence
in providing that medical treatment.” (Id. at pp. 540-541.)


14   The Industrial Accident Commission was replaced by the
Board in 1966. (Ramirez v. Workers’ Comp. Appeals Bd. (2017)
10 Cal.App.5th 205, 220, fn. 7.)




                              21
Such “independent suits” would “ultimately result in a
breakdown in the system of compensation for industrial
injuries and create unwarranted confusion and increased
unnecessary litigation . . . .” (Id. at p. 541; see also Noe v.
Travelers Ins. Co. (1959) 172 Cal.App.2d 731, 737 [“[I]f delay
in medical service attributable to a carrier could give rise to
independent third party court actions, the system of
workmen’s compensation could be subjected to a process of
partial disintegration. In the practical operation of the plan,
minor delays in getting medical service, such as for a few
days or even a few hours, caused by a carrier, could become
the bases of independent suits, and these could be many and
manifold indeed. The uniform and exclusive application of
the law would become honeycombed with independent and
conflicting rulings of the courts. The objective of the
Legislature and the whole pattern of workmen’s
compensation could thereby be partially nullified”].)
      Here, there is no dispute that the disabling carpal
tunnel syndrome from which petitioner suffered was largely
the result of her many years of clerical employment with
Costco. It followed that Costco was required to provide
medical treatment to resolve the problem, without
apportionment. The surgery went badly, leaving appellant
with a far more disabling condition -- CRPS -- that will never
be alleviated. California workers’ compensation law relieves
Costco of liability for any negligence in the provision of the
medical treatment that led to petitioner’s CRPS. It does not




                              22
relieve Costco of the obligation to compensate petitioner for
this disability without apportionment.
      Our review of the authorities convinces us that in
enacting the “new regime of apportionment based on
causation,” the Legislature did not intend to transform the
law requiring employers to pay for all medical treatment
caused by an industrial injury, including the foreseeable
consequences of such medical treatment. Pre-2004 law
constraining the application of apportionment in the award
of permanent disability benefits was based primarily on the
interpretation of former sections 4663 and 4750, which were
eliminated or fundamentally altered by the 2004
amendments. The longstanding rule that employers are
responsible for all medical treatment necessitated in any
part by an industrial injury, including new injuries resulting
from that medical treatment, derived not from those
statutes, but from (1) the concern that applying
apportionment principles to medical care would delay and
potentially prevent an injured employee from getting
medical care; and (2) the fundamental proposition that
workers’ compensation should cover all claims between the
employee and employer arising from work-related injuries,
leaving no potential for an independent suit for negligence
against the employer. Nothing in the 2004 legislation had
any impact on the reasoning that has long supported the
employer’s responsibility to compensate for medical
treatment and the consequences of medical treatment
without apportionment. Accordingly, the WCJ erred in




                              23
relying on the 2004 amendment to support apportioning
petitioner’s award, and the Board erred in upholding his
decision.
                       DISPOSITION
      The order of the Board on reconsideration is annulled.
The matter is remanded to the Board for further proceedings
consistent with the view expressed in this opinion.
Petitioner shall recover her costs.
      CERTIFIED FOR PUBLICATION




                                      MANELLA, J.

We concur:




EPSTEIN, P. J.




WILLHITE, J.




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