[¶ 1.] Allan Arends (Arends), employed by South Dakota State Cement Plant Commission d/b/a Dacotah Cement (Daco-tah) for over 30 years, fell through some ice and sustained an acute knee injury while he was out trapping muskrat. When surgery was performed, it was discovered that Arends had degenerative osteoarthritis. Both the Department of Labor (Department) and the circuit court determined that there was a work-related injury, which was a major contributing cause of the physical impairment. Arends was awarded benefits under South Dakota workers’ compensation law. We affirm.
FACTS AND PROCEDURE
[¶ 2.] Arends began working for Daco-tah in 1974, after spending time in the military and working for other concrete, steel and construction companies. While working for Dacotah, one of Arends’ primary duties as manager at the Watertown terminal was to unload rail cars. This, in turn, required repetitive stooping and kneeling on concrete.
[¶ 3.] Additionally, Arends had several hobbies, including working on cars, hunting, fishing, and trapping. These hobbies also required a significant amount of stooping and kneeling. On November 17, 1996, while out trapping muskrat, Arends fell through the ice with his left leg. The fall brought Arends’ entire body weight down on his right knee. The pain was instant and Arends heard a “clicking” noise in his knee. He had difficulty walking and his knee became swollen.
[¶ 4.] On November 25, 1996, one week after the accident, Arends saw Dr. Terry L. Seeman. Due to Arends’ inability to flex his knee since the time of the accident, Dr. Seeman recommended crutches and an MRI. The MRI revealed thinning throughout the meniscal cartilage, as well as ero-sions or spurs on the back of the patella. Dr. Seeman advised Arends not to return to work until he was off the crutches. On January 9, 1997, Dr. Seeman performed arthroscopic surgery which basically revealed: (1) an acute injury amounting to torn medial meniscus cartilage; and (2) a cumulative or chronic injury amounting to global thinning or degeneration of the cartilage and patella. Dr. Seeman stated:
The type of surface damage that he had is not something you would normally see in a 48[-]year[-]old who has a white collar or sit-down type of job. I mean, it’s just not that badly damaged as his was.
When asked what would cause that type of injury, Dr. Seeman replied that “it would have to be some type of repetitive trauma to the kneecap.” Dr. Seeman concluded that the fall through the ice could have caused the tear, but that the degenerative osteoarthritis was largely a result of an accumulation of small injuries brought on by the repetitive strain or exertion of Ar-ends’ work activities. He stated that the evidence taken from the history of the patient, the MRI and the surgery all indicate that Arends’ work activity was “a *586major contributing cause ... or contributing insult to the knee.”
[¶ 5.] Dr. Peter A. Looby, an expert hired by Dacotah, also examined Arends and diagnosed degenerative osteoarthritis of mild to moderate degree in both knees. Dr. Looby indicated that the progressive illness was “multifactorial” caused by genetic predisposition, wear and tear, and possibly aggravation from an acute trauma.
I believe his work was a contributing cause. His work involved standing on concrete, a lot of stooping, bending, lifting, those kinds of activities. And just as his recreational activities probably contributed to the development of osteoarthritis, probably so did his work environment.
Dr. Looby then stated that the condition essentially amounts to “an accumulation of small traumas and wear and tear on the joints.”
[¶ 6.] Arends reached maximum medical improvement on March 6, 1998. Because he could no longer perform his job, Dacotah required Arends to draw sick leave from April 22, 1997, to December 2, 1997.
[¶ 7.] Department held a hearing on July 26, 2000, and determined that Arends had a 17 percent impairment in his lower right extremity, that Arends’ work activities were a major contributing cause of the impairment, and that Arends was entitled to workers’ compensation benefits. The Hearing Officer awarded Arends temporary total disability benefits for the period in which he was required to draw sick leave. The Hearing Officer also determined, under the odd-lot doctrine, that Arends was entitled to permanent total disability benefits because of his condition, level of education, training, and age. Finally, the Hearing Officer denied Arends’ claim for the penalty provided in SDCL 62-4-10.1 on the ground that a good-faith dispute between the parties did exist.
[¶ 8.] Dacotah appealed this decision to the circuit court. While the court affirmed the decision of Department on July 6, 2001, it did overrule the Hearing- Officer’s finding of fact that Arends’ condition had not been worsened by the fall through the ice. The court concluded that this finding was clearly erroneous. Notwithstanding this determination, the circuit court upheld Department’s ruling that a work-related injury -was a major contributing cause of Arends’ disability. The circuit court also concluded that the last injurious exposure rule under SDCL 62 — 1—l(7)(c) did not apply because “this is not a case where subsequent employers are arguing over which one should be on the risk.” Finally, the court affirmed the Hearing Officer’s determination that a good-faith dispute did exist and, therefore, Arends was not entitled to a penalty under SDCL 62-4-10.1.
[¶ 9.] Dacotah now appeals to this Court raising the following issues:
1. Whether Arends suffered a work-related injury, which was a major contributing cause of the condition complained of.
2. Whether the last injurious exposure rule applies where there is no “subsequent employment.”
By Notice of Review, Arends raises the following issue for appeal:
3. Whether there is an absence of a good-faith dispute, entitling Arends to the penalty provided in SDCL 62-4-10.1.
STANDARD OF REVIEW
[¶ 10.] We review administrative decisions, such as those of Department, pursuant to the standard set forth in SDCL 1-26-36. We must give great weight to the agency’s findings of fact and *587overturn such findings only where they are clearly erroneous. Gilchrist v. Trail King Indus., Inc., 2000 SD 68, ¶ 4, 612 N.W.2d 1, 3 (citations omitted). “Only if after a review of the entire record we are definitely and firmly convinced a mistake has been committed will we reverse.” Id. (citations omitted). Conversely, findings of fact based solely upon deposition testimony are reviewed de novo. Goebel v. Warner Transp., 2000 SD 79, ¶ 10, 612 N.W.2d 18, 21 (citations omitted). When the issue is a question of law, we review the decisions of both the administrative agency and the circuit court de novo. Butte County v. Vallery, 1999 SD 142, ¶ 8, 602 N.W.2d 284, 286-87.
[¶ 11.] This case also involves statutory interpretation which, as a question of law, is reviewed by this Court de novo. Steinberg v. S.D. Dep’t of Military and Veterans Affairs, 2000 SD 36, ¶ 6, 607 N.W.2d 596, 599. “Words and phrases in a statute must be given their plain meaning and effect. When the language in a statute is clear, certain and unambiguous, there is no reason for construction, and the Court’s only function is to declare the meaning of the statute as clearly expressed.” Martinmaas v. Engelmann, 2000 SD 85, ¶ 49, 612 N.W.2d 600, 611 (quoting Moss v. Guttormson, 1996 SD 76, ¶ 10, 551 N.W.2d 14, 17) (additional citations omitted).
ANALYSIS AND DECISION
[¶ 12.] 1. Whether Arends suffered a work-related injury, which was a major contributing cause of the condition complained of.
[¶ 13.] “In order to collect worker’s compensation benefits, [Arends] must establish a causal relationship between his injury and his employment.” Gilchrist, 2000 SD 68 at ¶ 7, 612 N.W.2d at 3-4 (citing Kester v. Colonial Manor of Custer, 1997 SD 127, ¶ 17, 571 N.W.2d 376, 380 (additional citation omitted)). SDCL 62-1-1 provides the definition of “injury” for the purposes of South Dakota workers’ compensation.
Terms used in this title, unless the context otherwise plainly requires, shall mean: * * *
7) “Injury” or “personal injury,” only injury arising out of and in the course of the employment, and does not include a disease in any form except as it results from the injury. An injury is compensa-ble only if it is established by medical evidence, subject to the following conditions:
(a) No injury is compensable unless the employment or employment related activities are a major contributing cause of the condition complained of or
(b) If the injury combines with a preexisting disease or condition to cause or prolong disability, impairment, or need for treatment, the condition complained of is compensable if the employment or employment related injury is and remains a major contributing cause of the disability, impairment, or need for treatment.
(c) If the injury combines with a preexisting work related compensable injury, disability, or impairment, the subsequent injury is compensable if the subsequent employment or subsequent employment related activities contributed independently to the disability, impairment, or need for treatment. * * *
SDCL 62-1-1(7) (emphasis added). Thus, Arends must prove: (1) that his injury was work-related; and (2) that the work-related injury was a major contributing cause of the condition complained of, which is the physical impairment. “This causation re*588quirement does not mean that the employee must prove that [his] employment was the proximate, direct, or sole cause of [his] injury; rather the employee must show that [his] employment was a ‘contributing factor ’ to [his] injury.” Gilchrist, 2000 SD 68 at ¶ 7, 612 N.W.2d at 4 (quoting Kester, 1997 SD 127 at ¶ 17, 571 N.W.2d at 380 (additional citation omitted)) (alterations and emphasis in original).
[¶ 14.] As recognized by Department and the circuit court in this case, the medical evidence does establish that Ar-ends suffered work-related injuries. The injury is the act or omission that causes the loss. Grauel v. S.D. Sch. of Mines and Tech., 2000 SD 145, ¶ 9, 619 N.W.2d 260, 263 (citing Steinberg, 2000 SD 36 at ¶ 10, 607 N.W.2d at 600). In this case, one injury, the fall through the ice, did not occur during Arends’ performance of his job. But many others did. In fact, the medical evidence indicates that Arends suffered a series of injuries over the thirty-year period, which manifested in a degenerative disorder. The arthroscopic surgery, admittedly done in response to Arends’ fall through the ice, merely hastened discovery of the damage caused by these injuries.
[¶ 15.] In Grauel, we determined that the claimant had not established, by a preponderance of medical evidence, that his employment was a major contributing cause of the physical impairment. Id. at ¶¶ 19-21. There, the treating physician could offer no opinion as to whether he believed the degenerative condition in the claimant’s knee had happened over time or all at once. Id. at ¶ 20. He also assumed that because the injury happened at work, it was “ipso facto work-related.” Id. at ¶ 19. Moreover, the employer’s expert, after an independent medical examination, concluded that the degenerative osteoarthritis was a preexisting condition that caused the disability, unrelated to the claimant’s work activities. Id. at ¶ 21. In reviewing the deposition testimony and medical evidence, we concluded that the claimant had not carried his burden of showing that his employment was a major contributing cause of his disability
[¶ 16.] In this case, however, we agree with both Department and the circuit court that the repeated work-related trauma to Arends’ knee was a major contributing cause of the condition complained of. The condition, or loss produced by the injury, is the physical impairment caused by Arends’ degenerative osteoarthritis. See id. at ¶ 9. Findings taken from MRI, arthroscopic surgery, and the examinations of both doctors demonstrate to a reasonable medical probability that Ar-ends’ chronic condition was not caused by one acute injury; rather, it was caused by the cumulative trauma from years of bending, stooping and kneeling on concrete. See Truck Ins. Exch. v. CNA, 2001 SD 46, ¶ 19, 624 N.W.2d 705, 709. Therefore, unlike the claimant in Grauel, Arends has met his burden of demonstrating that the repetitive work at Dacotah caused him injuries which, in turn, were a major contributing cause of his disability. Given this evidence, we are not firmly convinced that a mistake has been made and we will not overturn the Department’s ruling.
[¶ 17.] 2. Whether the last injurious exposure rule applies where there is no “subsequent employment.”
[¶ 18.] While South Dakota has adopted the last injurious exposure rule, we agree with the circuit court’s conclusion that the rule does not apply in this case. See SDCL 62-l-l(7)(c). See also Enger v. EMC, 1997 SD 70, ¶ 12, 565 N.W.2d 79, 83 (stating “South Dakota has adopted the ‘last injurious exposure rule’ when consid*589ering successive injuries.”) (citations omitted). The statute provides:
If the injury combines with a preexisting work related compensable injury, disability, or impairment, the subsequent injury is compensable if the subsequent employment or subsequent employment related activities contributed independently to the disability, impairment, or need for treatment.
SDCL 62 — 1—1 (7)(c). Arends may have “a preexisting work related compensable injury, disability, or impairment” and a “subsequent injury,” but he does not have “subsequent employment.”
[¶ 19.] “[Workers’ compensation statutes should be applied without defeating the purpose of the overall statutory scheme.” Grauel, 2000 SD 145 at ¶ 14, 619 N.W.2d at 264 (citation omitted). The Legislature intended this section of the statute to settle disputes between two or more employers or insurers. Application of the doctrine to the facts of this case would not advance this purpose. Here, we have a dispute between the employer and employee to determine whether the employer-caused injuries or the employee-caused injury is responsible for the condition. But such disputes are already settled under the causation portion of the analysis. Therefore, there is no need to reach the last injurious exposure rule.
[¶20.] 3. Whether there is an absence of a good-faith dispute, entitling Arends to the penalty provided in SDCL 62-4-10.1.
[¶ 21.] Arends claims that because Da-cotah wrongfully failed to pay his claim for benefits within ten days, it should be subject to the penalty provision of SDCL 62-4-10.1. However, this Court has also held that the penalty is appropriate only in the absence of a good-faith dispute. See Tischler v. United Parcel Serv., 1996 SD 98, ¶ 77, 552 N.W.2d 597, 609. Herein, Dr. Seeman did not initially express the opinion that Arends’ work was a “major contributing cause” of the disability because he was not asked the question until his second deposition. Moreover, Dr. Looby continually maintained that, while he believed Arends’ work-related activities were a contributing cause, he was unable to say whether it was a “major” contributing cause. Liability depended upon the credibility of the testimony in light of the evidence. As the circuit court noted, there is no indication “of an abuse of discretion on the Hearing Examiner’s finding of a good-faith dispute.” Therefore, we affirm.
[¶ 22.] SABERS and KONENKAMP, Justices, and GORS, Acting Justice, concur.