{ 1 This matter addresses the timeliness of a worker's application to reopen his workers' compensation claim based on a change of condition for the worse under section 48(C) of the Workers' Compensation Act, Okla. Stat. tit. 85, §§ 1 through 211 (2001 & Supp. 2008). This Court determines that the worker's request was time barred.
12 Claimant, Robert Lang, suffered a compensable injury to his knee on June 12, 2001, in his employment with Exlanger Tubular Corp. (Employer). He was adjudicated permanently and partially disabled by an order filed on July 1, 2008. The order provided for continuing medical maintenance. That adjudication was followed on July 8, 20083, by an Order for Vocational Examination.
18 At a time not fully revealed by the record on appeal, Claimant's medical condition worsened. In October, 2006, surgery was performed on the knee to remove loose bodies from the joint and also for traumatic chondromalacia. An infection developed and Claimant underwent additional surgery in November, 2006. Employer's insurance company paid for the surgeries. It was not until May 15, 2007, however, that Claimant filed a Form 9 to reopen his claim based on a change of condition for the worse.
The Workers' Compensation Court denied Claimant's "Motion to Reopen" based on "the statute of limitations." The Court of Civil Appeals sustained the order and this Court granted certiorari review to hold that an application to reopen a claim for change of condition for the worse is controlled by section 43(C) which does not contain the "medical treatment rule" found in section 48(A)2 As a result, Claimant's application to reopen the claim is time barred.
ANALYSIS
T5 This matter seeks a construction of a statute and therefore it presents an issue of law. As such, it is reviewed de novo. See Kluver v. Weatherford Hosp. Auth., 1993 OK 85, ¶ 14, 859 P.2d 1081, 1084.
T 6 Section 48 of the Workers' Compensation Act contains two provisions which impact this matter. Section 48(A) provides a two-year limitations period for the filing of a worker's claim for compensation. That period begins with the date of injury or from "the last medical treatment which was authorized by the employer or the insurance carrier or payment of any compensation or remuneration paid in Hen of compensation." Okla. Stat. tit. 85, § 48(A) (Supp.2008). Thus, the Oklahoma Legislature has expressly incorporated what the parties term a "medical treatment rule" into the text of the limitation period for the filing of a claim for compensation.
T7 Section 48 contains a separate time limitation for reopening a claim for compensation based on a change in medical condition for the worse. The current version of seetion 48(C) requires such an application to be filed within three years "from the date of the last order."3 No medical treatment rule is expressed concerning an application to reopen a claim for a change of condition for the worse. Claimant argues, however, that although "no Oklahoma court has applied the 'medical treatment rule to toll the limitations period prescribed by Section 48(C) ... this Court should apply that rule when a[n] em*591ployer voluntarily pays for medical treatment...."
18 "The primary goal of statutory construction is to ascertain and follow the intention of the Legislature. If a statute is plain and unambiguous and its meaning clear and no occasion exists for the application of rules of construction a statute will be accorded the meaning expressed by the language used." Wylie v. Chesser, 2007 OK 81, ¶ 19, 173 P.3d 64, 71 (quoting TRW/Reda Pump v. Brewington, 1992 OK 31, ¶ 5, 829 P.2d 15, 20). "It is the duty of courts to give effect to legislative acts, not to amend, repeal or circumvent them. A'court is not justified in ignoring the plain words of a statute." Smalygo v. Green, 2008 OK 34, ¶ 11 n. 4, 184 P.3d 554, 559 n. 4 (quoting Allgood v. Allgood, 1981 OK 21, ¶ 19, 626 P.2d 1323, 1327).
19 Beginning in the 1980's, this Court articulated a medical treatment tolling rule to the filing of a workers' compensation claim. Thompson v. Anchor Glass Container Corp., 2003 OK 39, ¶ 10 n. 16, 73 P.3d 836, 838. Later, the Legislature incorporated the rule into the text of the time bar for the initial filing of a compensation claim. This Court has never held that the medical treat: ment rule is applicable across-the-board to all time bars in workers' compensation. It spoke only to the initial filing of a claim.
110 The Legislature eventually drew a distinction between a "claim for compensation," as that term is used in section 48(A), and an "application to reopen a claim" in section 48(C) by enacting two separate provisions. -It treated the provisions very differently when it incorporated the medical treatment rule into the text of section 48(A) but chose not to incorporate that same rule into section 43(C). But the Legislature went further. In section 48(C) it expressed its intent to limit specifically "[the jurisdiction of the [Workers' Compensation] Court to reopen any cause" based on a change of condition to three years from "the date of last order." In doing so, the Legislature could not have more clearly expressed its intent.4
[ 11 The section 43(C) time bar is a statement of legislative intent that is contrary to its acceptance of the judicially created and legislatively adopted medical treatment rule contained in section 48(A). This Court is not at liberty to apply a medical treatment rule to the time bar of section 48(C) and thereby contravene the Legislature's unambiguous limitation on the jurisdiction of the Workers' Compensation Court to reopen a claim.
112 This Court is not free to ignore the Legislature's expressed intent by imposing an adverse judicial "gloss." The statutory time bars contained in the Act are not one entity. They involve different demands for action by the Workers' Compensation Court and implicate different policies. The need to give effect to an employer's acts that indicate its assumption of liability, such as by providing medical treatment, are not compelling as to an application to reopen an adjudicated claim. The Legislature was free to draw a distinction between the time bar for filing an original claim and the time bar for an application to reopen a claim.
113 Because the medical treatment rule applies only to the filing of a workers' compensation claim, the parties' arguments as to whether Claimant met the requirements for such a rule do not impact this Court's determination of the timeliness of his application to. reopen the claim based on a change of condition for the worse pursuant to section 48(C). An issue remains, however, concerning which version of section 48(C) applies to this matter.
114 Section 48(C) was amended effective July 1, 2005, to provide for a uniform three-year limitation period and to make the "date of the last order" the sole operative event that marks the beginning of that period. In earlier versions of section 48(C), the limitation period ran from the date of the change of condition. The application to reopen had to be filed within that same limitation period *592from the date of the last order.5 In addition, the limitation period varied depending on the injury adjudicated. Under the current version, the date of change of condition no longer marks the beginning of the limitation period. However, the date of the change of condition determines which version of section 48(C) applies. "The law governing the reopening of a compensation claim upon a change in condition is that which was in effect at the time the claimant's condition underwent a change, and not the law in effect at the time of the injury or the law in force at the time of the original award." Arrow Tool & Gauge v. Mead, 2000 OK 86, ¶ 7, 16 P.3d 1120, 1123.
1 15 There are three dates which must be determined by the Workers' Compensation Court in applying section 43(C). First, the date of the change of condition must be determined in order to apply the correct version of section 43(C). Second, "the date of last order" must be established to mark the beginning of the limitation period. "[The last order means one that substantially affects the monetary, medical, or rehabilitative benefits conferrable by the Act. An order directing ... a vocational rehabilitation evaluation is one that ... qualifies as a last order within the meaning of [section] 43(C)." Id. ¶ 22, 16 P.3d at 1127 (emphasis omitted). Third, the date of the application to reopen the claim establishes whether it has been filed beyond the limitation period. The need for meaningful judicial review requires that these dates appear in any order from the Workers' Compensation Court which determines the timeliness of an application to reopen a claim upon a change of condition for the worse pursuant to section 43(C). See Dunkin v. Instaff Personnel, 2007 OK 51, ¶ 18, 164 P.3d 1057, 1062.
116 This matter demonstrates the continued relevance of the date of change of condition and the need for a specific on-the-record finding as to that date. Although no date of change of medical condition appears in the record on appeal, Claimant's Brief-in-Chief states that the current version of seetion 43(C) was in effect at the time of Claimant's change of condition. This is significant because the prior version would have provided 250 weeks from the date of last order in which to apply to reopen the claim and Claimant's request would have been timely.6 Under the current and applicable version, however, Claimant had three years from the July 8, 2008, "last order" in which to timely apply to reopen the claim.7 Claimant's application to reopen was not filed until May 15, 2007, and it was therefore barred by the limitation period of the 2005 version of seetion 43(C). The Workers' Compensation Court did not err in so holding.
CERTIORARI PREVIOUSLY GRANT ED; OPINION OF COURT OF CIVIL APPEALS VACATED; ORDER OF WORKERS' COMPENSATION COURT SUSTAINED.
*593Coneur: EDMONDSON, C.J., TAYLOR V.C.J., HARGRAVE, WATT, WINCHESTER, COLBERT, REIF, JJ. Dissent: OPALA, KAUGER, JJ.. The current version of the statute as amended effective July 1, 2005, provides:
A. The right to claim compensation under the Workers' Compensation Act shall be forever barred unless, within two (2) years after the date of accidental injury or death, a claim for compensation is filed with the Workers' Compensation Court. Provided however, a claim may be filed within two (2) years of the last medical treatment which was authorized by the employer or the insurance carrier or payment of any compensation or remuneration paid in lieu of compensation....
Okla. Stat. tit, 85, § 43(A) (Supp.2008).
. The current version of the statute as amended effective July 1, 2005, provides:
C. The jurisdiction of the Court to reopen any cause upon an application based on a change of condition for the worse shall extend three (3) years from the date of the last order and unless filed within said period of time, shall be forever barred. An order denying an application to reopen a claim shall not extend the period of the time set out herein for reopening the case.
Okla Stat. tit. 85, § 43(C) (Supp.2008).
. ''Timely filing of a motion to reopen is jurisdictional under the express language of § 43(C), and without jurisdiction the Workers' Compensation Court may not act." Pickett v. Oklahoma Dept. Of Human Servs., 1996 OK CIV APP 142, ¶ 12, 932 P.2d 543, 546. No Oklahoma authority has applied a medical treatment rule to section 43(C). Matthews v. General Motors, 2009 OK CIV APP 4, ¶ 6, 2008 WL 5543901.
. The 2001 version of the statute was in effect until it was amended in 2005. It provided:
C. The jurisdiction of the Court to reopen any cause upon an application based upon a change in condition shall extend for that period of time measured by the maximum number of weeks that could be awarded for the particular scheduled member where the change of condition occurred, or for two hundred and eight (208) weeks in the case of injuries to the body or injuries not otherwise scheduled under the provisions of Section 22 of this title, and unless filed within said period of time after the date of the last order, shall be forever barred. An order denying an application to reopen a claim shall not extend the period of the time set out herein for reopening the case.
Okla. Stat. tit. 85, § 43(C) (2001).
. Confusion was injected into this review proceeding through reference to the wrong version of section 43(C) by the Court of Civil Appeals. The opinion purported to apply the 2001 version. of the statute and specifically held that the 2005 amendment did not apply. Under the 2001 version, however, the application to reopen would have been timely. The confusion is particularly curious given Claimant's admission that the shorter limitation period found in the 2005 amendment applies. If the date of Claimant's change of condition had been included in the order of the Workers' Compensation Court or if that court had cited the version of section 43(C) it believed applicable, the risk of confusion by a reviewing court would have been minimized.
. Claimant's two surgeries were performed outside the three-year limitation period which expired in July, 2006. Therefore, Claimant is asking not only that this Court read a medical treatment rule into section 43(C), but to actually revive his time-barred application based on Employer's voluntary payment for the surgeries.