FOX, Justice.

[¶ 1] The Wyoming Department of Workforce Services, Workers' Safety and Compensation Division (Division) determined that Phylis Stevens' avascular necrosis (AVN) in her right hip was not caused by her October 2010 slip and fall at work, and denied her claim for medical treatment of the AVN. After a contested case hearing, the hearing examiner for the Office of Administrative Hearings (OAH) agreed with the Division that Mrs. Stevens' right hip AVN was not caused by her fall at work. The district court affirmed the decision, and Mrs. Stevens appealed. We affirm.

ISSUES

[¶ 2] 1. Was there substantial evidence to support the hearing examiner's determination that Mrs. Stevens' fall did not cause the avascular necrosis in her right hip?

2. The hearing examiner concluded that the absence of evidence of disease prior to the work-related injury and the presence of the disease afterwards was not sufficient to establish a causal link. Was that conclusion in accordance with the law?

FACTS

[¶ 3] On October 25, 2010, Phylis Stevens slipped and fell down a flight of stairs outside of her workplace, the Pinedale Aquatic Center (PAC). Mrs. Stevens crawled back into the PAC where she was assisted by several of her co-workers.

[¶ 4] Shortly thereafter, her husband transported her to the Pinedale Medical Clinic. At the clinic, Mrs. Stevens was seen by a physician's assistant who diagnosed fractures to her fourth finger and fifth metacarpal in her left hand. According to Mrs. Stevens' intake form, she was ambulatory on arrival, her "chief complaint" was pain in her left hand, and she denied any other injuries from the fall. She was referred to Teton Orthopedics for surgery on her hand.

[¶ 5] The following day, Dr. Peter Rork of Teton Orthopedics saw Mrs. Stevens, took x-rays, and performed surgery to repair her fractured hand. Her pain assessment chart indicated pain in her left hand and arm only. She was discharged with pain medication, and over the next several months, Mrs. Stevens returned to Dr. Rork to monitor the recovery of her hand.

[¶ 6] Julie Huntley, PAC Director, met with Mrs. Stevens two days after the fall to fill out a Wyoming Report of Injury. The report contains no indication that Mrs. Stevens injured her hip in the fall or was suffering from any hip pain at the time of the report.

[¶ 7] On October 29, 2010, Mrs. Stevens returned to work for the PAC Halloween festivities. At that time she felt soreness in her right hip, but she thought it would go away.

[¶ 8] On November 2, 2010, Mrs. Stevens followed up with Dr. Rork. Dr. Rork's notes from that visit indicate that her hand was healing well, and he would follow up with her in three weeks. There is no mention of any other medical problems in Dr. Rork's notes.

[¶ 9] On November 10, 2010, the Division issued its Final Determination of Compensability, in which it found Mrs. Stevens' hand injury compensable.

[¶ 10] On November 29, 2010, Mrs. Stevens again followed up with Dr. Rork at Teton Orthopedics, who determined her hand was healing well. At the conclusion of the visit with Dr. Rork, Mrs. Stevens mentioned for the first time the soreness in her right hip. Dr. Rork thought she had developed bursitis in her right hip and prescribed an anti-inflammatory for relief.

[¶ 11] Mrs. Stevens' next visit with Dr. Rork was on December 23, 2010. At that time, Dr. Rork noted her hand wounds were clear, she was nontender, with increasing range of motion, and he would follow up in one month. There is no mention of Mrs. Stevens' hip in Dr. Rork's record of the visit.

[¶ 12] On January 13, 2011, approximately two and one-half months after her fall, Mrs. Stevens visited the Pinedale Medical Clinic, complaining of pain in her right hip. During the visit, x-rays were taken of both her hips, and no abnormal findings were detected. She was diagnosed with a possible tendon tear or bursitis in the right hip and scheduled for an MRI.

[¶ 13] On January 17, 2011, Mrs. Stevens obtained an MRI of her hips. The radiologist's interpretation of the MRI was as follows:

That day, interpreting the results of the MRI, Dr. Rork diagnosed Mrs. Stevens with AVN in the femoral head of her right hip. (AVN is the death of a bone due to lack of blood supply.) Dr. Rork noted, "This is probably a post-traumatic event related to the slip and fall accident of 10/26/10 [sic]. I am going to put her on crutches. We will see her back for follow up in 6 weeks[.]"

[¶ 14] At her February 28, 2011, follow-up, Dr. Rork's notes indicate, "[Mrs. Stevens] was complaining of hip pain that occurred at the time of the initial injury, this was probably overshadowed by the pain in her left hand. What has occurred is that she has gone on to an AVN which may or may not require surgical intervention."

[¶ 15] On April 25, 2011, another MRI was taken of Mrs. Stevens' hips. The radiologist's report from this MRI provided the following interpretation:

[¶ 16] Dr. Rork's April 25 notes indicate, "[Mrs. Stevens] states that her hip is feeling better." However, regarding the MRI, Dr. Rork noted, "shows fracture of the femoral head [on right hip] with some mild degenerative changes in the left hip." Dr. Rork decided to take her off the crutches and start her on water therapy. Eventually, the femoral head on her right hip collapsed due to the AVN progression, and on December 14, 2011, Mrs. Stevens received a total right hip replacement.

[¶ 17] On February 18 and March 1, 2011, the Division issued its Final Determinations, denying all payments for Mrs. Stevens' hip-related treatment based on the conclusion that "the right hip is not related to the original work injury to the left hand[.]" Mrs. Stevens timely requested a contested case hearing, which was held December 7, 2012.1

[¶ 18] At the hearing, three of Mrs. Stevens' colleagues from the PAC testified on her behalf: Charlotte Keyser, Ellen Ramsey, and Julie Huntley. There were no eyewitnesses to Mrs. Stevens' fall and she could not remember exactly how she fell down the concrete stairs, other than she slipped, twisted or turned in the fall, and ended up with her left hand tangled up on the railing and her lower body straddling the last few steps. She crawled up the stairs, pushed the handicap button to open the doors, and crawled into the foyer of the PAC. Once inside, she began screaming for help, and the evening custodian, Charlotte Keyser, responded.

[¶ 19] Ms. Keyser found Mrs. Stevens lying in the fetal position in the PAC foyer crying for help. On direct examination at the contested case hearing, Ms. Keyser was asked to testify as to what Mrs. Stevens reported to her about the fall, to which she responded "Oh gosh, I don't remember." Later in her testimony, Ms. Keyser reported that Mrs. Stevens was clutching her wrist and also indicated that she hurt her right hip in the fall. Ms. Keyser further testified, "I was more concerned about her wrist, because that's what looked — visually, that's where the problem was." After assisting Mrs. Stevens into a seated position inside the main area of the PAC, fellow PAC employees Sue Phlughoft2 and Ellen Ramsey took over her care.

[¶ 20] Ellen Ramsey testified that she first saw Mrs. Stevens at a table in the PAC lobby shortly after she fell and she approached to see if she could help. Ms. Ramsey testified that she remembered Mrs. Stevens sitting on a table by the lobby doors, and "she was screaming in pain." In response to Ms. Phlughoft's question if she was hurt elsewhere, Ms. Ramsey remembered Mrs. Stevens telling Ms. Phlughoft that her hip was hurting and then making a head gesture toward her right side. On cross examination, Ms. Ramsey indicated that in a conversation two weeks after the fall, Mrs. Stevens talked about her wrist injury, did not talk about any hip pain, and was not limping. Ms. Ramsey did testify that approximately four weeks later Mrs. Stevens was limping and mentioned her hip pain to Ms. Ramsey in conversation.

[¶ 21] Julie Huntley recounted her interactions with Mrs. Stevens after the fall, specifically, meeting her two days later to fill out the Wyoming Report of Injury: "Oh, I just remember she said how sore she was, generally speaking, and that her hand was — she definitely had a hand injury, and that she was sore everywhere. And beyond that, you know, I wouldn't be able to tell you." Ms. Huntley did testify that "somewhere in there within a couple of weeks" after Mrs. Stevens' fall, she observed her limping and told her to go get it checked out. The Wyoming Report of Injury contained no indication that Mrs. Stevens hurt her hip in the fall.

[¶ 22] Although the hearing examiner found each of these women credible, she stated in her Findings of Fact, Conclusions of Law, and Order, "suffice it to say that the Office finds and concludes that any statements or implications that Stevens had significant pain in the hip immediately after the fall are not supported."

[¶ 23] Mrs. Stevens testified about her fall and treatment to her wrist and hip. She indicated that her hip started to hurt immediately following the fall. However, the documentation of her fall and subsequent care did not indicate any hip pain until her first mention of hip pain to Dr. Rork on November 29, and her hip did not become the focus of her care until January 2011. From Mrs. Stevens' testimony, the hearing examiner found and concluded:

[¶ 24] Mrs. Stevens offered the deposition of her treating physician, Dr. Rork, at the hearing. Summarizing the manifestation of her hip injury, he explained:

When asked whether her slip and fall caused or aggravated some preexisting condition that caused AVN, Dr. Rork insisted: "I think this is a post-traumatic event. I think that her avascular necrosis occurred — began with that fall." Explaining the basis for his opinion, Dr. Rork, testified:

[¶ 25] On cross examination, it was noted that Mrs. Stevens was seen at the Pinedale Clinic after the fall and denied any pain in the pelvic area. Dr. Rork agreed that this would be inconsistent with a person who had twisted the hip or had a trauma to their hip sufficient to cause AVN.

[¶ 26] Also under cross examination, Dr. Rork was asked about the presence of bilateral AVN and how that affected his opinion.

[¶ 27] The Division presented the medical report and deposition of Dr. Bruce Newton. At the Division's request, Dr. Newton performed an independent medical evaluation of Mrs. Stevens on September 27, 2011. Dr. Newton's report was comprehensive in scope and detail, including a review of Mrs. Stevens' medical history, a review of all records including x-rays and MRIs taken in the course of Mrs. Stevens' hand and hip treatment, as well as a physical examination of Mrs. Stevens. In his report, Dr. Newton concluded:

[¶ 28] In her final decision denying Mrs. Stevens' benefits for her hip, the hearing examiner concluded:

[¶ 29] Mrs. Stevens timely petitioned the Ninth Judicial District Court for review of the OAH decision to deny benefits. On November 26, 2013, the district court issued its decision affirming the OAH decision. This appeal followed.

DISCUSSION

I. Was there substantial evidence to support the hearing examiner's determination that Mrs. Stevens' fall did not cause the avascular necrosis in her right hip?

[¶ 30] On appeal from a district court's review of an administrative decision, we review the case as if it came directly from the administrative agency. Hirsch v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2014 WY 61, ¶ 33, 323 P.3d 1107, 1115 (Wyo. 2014) (citing Birch v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2014 WY 31, ¶ 12, 319 P.3d 901, 906 (Wyo.2014)). Our review is governed by Wyo. Stat. Ann. § 16-3-114(c) (LexisNexis 2013); we examine agency findings of fact by applying the substantial evidence standard. Birch, 2014 WY 31, ¶ 12, 319 P.3d at 906.

[¶ 31] Substantial evidence "means relevant evidence that a reasonable mind might accept as adequate to support a conclusion." Green v. State ex rel. Dep't of Workforce Servs., Workers' Safety & Comp. Div., 2013 WY 81, ¶ 13, 304 P.3d 941, 946 (Wyo.2013) (citing Jacobs v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2013 WY 62, ¶ 8, 301 P.3d 137, 141 (Wyo.2013)). "`Findings of fact are supported by substantial evidence if, from the evidence preserved in the record, we can discern a rational premise for those findings.'" Id. (quoting Kenyon v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2011 WY 14, ¶ 11, 247 P.3d 845, 849 (Wyo.2011)). Whether we might reach the same result or not, we will not reweigh the evidence, but instead defer to the OAH's decision if it is based upon relevant evidence that a reasonable mind might accept. See Torres v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2011 WY 93, ¶ 24, 253 P.3d 175, 181 (Wyo.2011).

[¶ 32] If an agency's decision determines that the claimant failed to meet her burden of proof, under our substantial evidence standard, "`this Court must decide whether [the] determination was contrary to the overwhelming weight of the evidence.'" Hirsch, 2014 WY 61, ¶ 34, 323 P.3d at 1115 (quoting Leavitt v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2013 WY 95, ¶ 18, 307 P.3d 835, 840 (Wyo.2013)). On review, the appellant has the burden of demonstrating that the findings of fact were not supported by substantial evidence. Watkins v. State ex rel. Wyo. Med. Comm'n, 2011 WY 49, ¶ 16, 250 P.3d 1082, 1086 (Wyo.2011) (citing Anaya v. Holly Sugar Corp., 928 P.2d 473, 475 (Wyo.1996)).

[¶ 33] Mrs. Stevens argues that the hearing examiner's determination that her fall did not cause her AVN is contrary to the overwhelming weight of the evidence. She challenges the hearing examiner's conclusion that the opinion of the Division's physician, Dr. Newton, was stronger and more persuasive than the opinion of her expert and treating physician, Dr. Rork. She argues that Dr. Newton's opinion that subluxation of her right hip did not occur is based on a misunderstanding of her fall; his opinion regarding the force and direction necessary for a subluxation of the hip was contradictory; and his opinion that Mrs. Stevens suffered bilateral AVN was not supported by substantial evidence.

[¶ 34] The Division asserts that Mrs. Stevens' and her co-workers' retrospective testimony indicating she immediately had pain in her hip following the fall is inconsistent with the medical documentation describing her injuries following the fall. In light of this inconsistency, the Division contends it was appropriate to weigh the conflicting opinions of the medical experts in this case in order to determine causation. On this front, the Division argues that Mrs. Stevens' medical expert presented speculative testimony which relied on assumption more than on the actual evidence. The Division supports the finding of the hearing examiner that Dr. Newton

[¶ 35] A compensable injury is one "arising out of and in the course of employment[.]" Wyo. Stat. Ann. § 27-14-102(a)(xi) (LexisNexis 2013). In order to show that the compensable injury arises out of or in the course of employment, the workers' compensation claimant has the burden of proving each of the essential elements of the claim by a preponderance of the evidence, including a causal connection between the work-related incident and the injury. Delacastro v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2014 WY 40, ¶ 22, 321 P.3d 327, 333 (Wyo. 2014).

[¶ 36] The OAH hearing examiner was tasked with determining whether Mrs. Stevens' AVN, which ultimately resulted in replacement of her right hip, was caused by her October 2010 fall outside of the PAC.3 To resolve the issue of causation, the hearing examiner looked to the expert medical testimony presented by Mrs. Stevens and the Division. When presented with conflicting expert medical testimony, the hearing examiner determines the credibility and weight of the experts' opinions.

Little v. State ex rel. Dep't of Workforce Servs., 2013 WY 100, ¶ 37, 308 P.3d 832, 843 (Wyo.2013) (citations omitted).

[¶ 37] Mrs. Stevens' claim that the hearing examiner's decision was not supported by substantial evidence is based on the assertion that the hearing examiner did not properly weigh the expert testimony presented at the contested case hearing. She argues that Dr. Newton's determination that her hip did not sublux4 was improperly based on his misunderstanding of Mrs. Stevens' fall.

[¶ 38] We agree that Dr. Newton's testimony on the mechanism of the fall was equivocal. However, regardless of disagreement over whether a posterior — or anterior-forced subluxation is sufficient to cause AVN, Dr. Newton's testimony did indicate that trauma-induced AVN is usually caused by a significant injury such as a femoral neck fracture or dislocation of the hip joint. He concluded that in the absence of any immediately documented reports of such a significant injury, or imaging data indicating a femoral neck fracture or dislocation to Mrs. Stevens' right hip from the fall, she did not sustain the force sufficient for trauma-induced AVN.

[¶ 39] Mrs. Stevens argues that Dr. Newton's misunderstanding of the fall and his opinion drawn therefrom contradicts the overwhelming weight of evidence presented at the hearing. She argues that her testimony at the hearing "clearly showed" that she had not simply fallen on her buttocks, but fell down a flight of concrete steps, "going forward and down the stairs, twisting and turning as she fell, eventually landing on her right hip with her right knee jammed into the bottom steps." She argues that her physician, Dr. Rork, had a clear understanding of how she fell, and that his understanding fits his theory that she subluxed her hip.

[¶ 40] Having reviewed the record, we cannot find any evidence that Mrs. Stevens fell forward in her fall down the steps. At the hearing, Mrs. Stevens testified:

[¶ 41] Mrs. Stevens' own treating physician appeared not entirely clear on the mechanism of Mrs. Stevens' fall: "You know, I don't recall the mechanism of action." Instead, Dr. Rork used the case of pro athlete Bo Jackson to analogize Mrs. Stevens' hip injury. Dr. Rork stated, "they theorize" that he "probably had a transient subluxation of the hip" that caused him to develop AVN. Dr. Rork indicated that the deep bruise on Mrs. Stevens' right hip and the initial findings on the MRI were "consistent with a mild subluxation such as Bo Jackson." Regarding Dr. Rork's use of Bo Jackson's injury, the hearing examiner found, "this ... seemed to then become the focus of the case. Indeed it appeared to be the only mechanism of injury that would provide the causal connection to the work related injury." The hearing examiner concluded:

"If, in the course of its decision making process, the agency disregards certain evidence and explains its reasons for doing so based upon determinations of credibility or other factors contained in the record, its decision will be sustainable under the substantial evidence test." Dale v. S & S Builders, LLC, 2008 WY 84, ¶ 22, 188 P.3d 554, 561 (Wyo. 2008).

[¶ 42] Mrs. Stevens' lack of clarity and Dr. Rork's conjecture hardly paint a clear picture of the type of fall suffered by Mrs. Stevens. While Dr. Newton's understanding of Mrs. Stevens' fall may not be complete, his explanation of the significant amount of force necessary to cause AVN is compelling regardless of how Mrs. Stevens fell. Dr. Newton reiterated several times in his deposition testimony that trauma-induced AVN would require a significant force, which in turn would likely register as a serious, immediately reportable, injury to the patient. The hearing examiner's determination that the facts did not support a finding of the severe hip injury required to cause trauma-induced AVN is supported by substantial evidence.

[¶ 43] Dr. Newton provided two additional reasons5 why the fall did not cause Mrs. Stevens' AVN. He opined that the time of onset of Mrs. Stevens' AVN was not consistent with trauma-induced AVN. Mrs. Stevens' medical records indicate that her hip pain did not reach a reportable level until one month after her fall, and she was diagnosed with AVN three months after the fall, which Dr. Newton testified, "is exceptionally fast for the development of AVN following trauma." Dr. Newton relied on a peer-reviewed article which examined the onset of symptoms and diagnoses of 146 patients who actually fractured or dislocated their hip, "a population where you're actually looking for [trauma-induced AVN]." Dr. Newton reported that even in this population, the range of onset of symptoms of AVN ranged from 3 to 47 months, and the average time of diagnosis was 18.8 months. Mrs. Stevens' onset of symptoms, as well as her AVN diagnosis within three months of the fall, are statistically inconsistent with the data presented by Dr. Newton.

[¶ 44] Finally, Dr. Newton considered the fact that Mrs. Stevens' April MRI revealed bilateral AVN, "which would not occur with an injury to — to a right hip. You wouldn't have AVN on the left side as a result of that." In other words, trauma-induced AVN to the right hip would not explain AVN in the left hip.

[¶ 45] On this final point, Mrs. Stevens argues that "for over two years after the original fall, Mrs. Stevens did not have any problems with her left hip up to the date of hearing date [sic] on December 7, 2012; ruling out AVN was a systemic condition." While the hearing examiner did not address this in her final determination, Dr. Newton testified:

Dr. Newton's explanation of Mrs. Stevens' bilateral AVN is well-reasoned and fits within the earlier explanations he gave regarding the onset of trauma-induced AVN. On the other hand, Dr. Rork simply dismissed the fact that Mrs. Stevens' April MRI revealed bilateral AVN, but did acknowledge that it "would throw a wrench in" his opinion if there was bilateral AVN.

[¶ 46] Mrs. Stevens has failed to establish that the hearing examiner's deference to Dr. Newton's expert opinion was contrary to the overwhelming weight of evidence. While Mrs. Stevens' expert medical testimony was speculative in nature, Dr. Newton provided articulate explanations for his opinion based on a comprehensive review of Mrs. Stevens' complete medical history as well as a physical exam of Mrs. Stevens. The hearing examiner considered both expert opinions, explained the weaknesses in Dr. Rork's speculative testimony, and ultimately found the weight of Dr. Newton's opinion most persuasive. We conclude that the hearing examiner, as trier of fact, could reasonably conclude as she did, based on all the evidence before her. Accordingly, there was substantial evidence to support the hearing examiner's final determinations.

II. The hearing examiner concluded that the absence of evidence of disease prior to the work-related injury and the presence of the disease afterwards was not sufficient to establish a causal link. Was that conclusion in accordance with the law?

[¶ 47] We review an agency's conclusions of law de novo, and will affirm only if the agency's conclusions are in accordance with the law. Wyo. Stat. Ann. § 16-3-114(c); Kenyon, 2011 WY 14, ¶ 13, 247 P.3d at 849. When reviewing a mixed question of law and fact, we separate the factual and legal aspects of the hearing examiner's decision to determine whether the correct rule of law has been properly applied to the facts. City of Casper v. Haines, 886 P.2d 585, 587 (Wyo.1994) (citing Aanenson v. State ex rel. Wyo. Workers' Comp. Div., 842 P.2d 1077, 1079-80 (Wyo.1992)).

[¶ 48] Mrs. Stevens argues that the hearing examiner erred as a matter of law by failing to apply the holding of Murray v. State ex rel. Wyo. Workers' Safety & Comp. Div., 993 P.2d 327 (Wyo.1999) to the facts of her case. She contends that, under Murray, her good health prior to the fall and the changes afterward are sufficient to find a causal connection between the fall and her right hip AVN, even when there is conflicting expert medical testimony regarding causation.

[¶ 49] In Murray, the claimant was working as a plant operator at a gas processing plant. 993 P.2d at 328. Murray drew a routine sample of raw gas and approximately 15 to 20 minutes later, he suffered an outbreak of a severe rash on his wrists. Id. Murray was eventually diagnosed with urticaria, but when his doctor attempted more allergy tests to determine the specific cause, Murray suffered severe, life-threatening allergic reactions. Id. at 329. The severity of these reactions prevented further testing, and left the determination of the cause of his urticaria inconclusive. Id. The Division denied his claim for benefits. Id.

[¶ 50] At the contested case hearing, Murray's treating physician opined that exposure to chemicals in his gloves at work likely caused his rash. Id. at 331. The Division's doctor "did not disagree, but stated that he could not offer the same opinion to a reasonable degree of medical certainty due to the limitations of the present science in identifying a specific cause." Id. at 332.6 Both doctors agreed that "something happened," but that the tests for causation were inconclusive. Id. Lacking proof of causation, the hearing officer denied benefits to Murray.

[¶ 51] On appeal, we held that "proof of prior good health and change immediately following and continuing after an injury may establish that an impaired condition was due to the injury." Id. (citing Waldorf Corp. v. Industrial Comm'n, 303 Ill.App.3d 477, 236 Ill.Dec. 890, 708 N.E.2d 476, 480 (1999)). We further stated:

Id. (internal citations and quotation marks omitted).

[¶ 52] Murray presented uncontradicted evidence that his injury occurred while he was at work, and that it was triggered when he collected the sample of raw gas. Murray's treating physician and the Division's expert agreed that "something happened" at work, the onset of his symptoms was immediate, the causation tests were inconclusive, and further testing would be dangerous to Murray. While Murray's treating physician testified that the urticaria was caused by something in Murray's gloves, the Division's expert did not disagree but refused to offer a similar opinion to a reasonable degree of medical certainty due to the limitations of science in identifying specific causes to urticaria. Id. at 333. Considering the uncontradicted evidence, the immediacy of the onset of symptoms, and the limitations of science, we reversed in favor of Murray.

[¶ 53] We recognized in Murray that, in certain circumstances, the temporal connection between a work-related incident and an adverse change in health can be "a competent way of studying causation." Id. at 332. We did not hold that such a temporal relationship will necessarily be sufficient to establish causation. In fact, in Murray we cautioned, "where a medical question is complex, and the fact finding must be done in a realm that appropriately relies upon technical medical knowledge and expertise, medical testimony should not be ignored." Id. (quoting Forni v. Pathfinder Mines, 834 P.2d 688, 693 (Wyo.1992)).

[¶ 54] Here, the circumstances are more complex than in Murray. The two experts disagreed regarding the cause of Mrs. Stevens' AVN. Mrs. Stevens made no documented report of her hip problems for over a month after her fall, and did not seek treatment for more than two months after the fall. While her co-workers testified that Mrs. Stevens immediately indicated pain in her hip following the injury, this testimony conflicted with the absence of documentation of any hip pain. Thus, the hearing examiner gave little weight to their testimony regarding the immediate onset of hip pain following Mrs. Stevens' fall. "`Credibility determinations are the unique province of the hearing examiner, and we eschew re-weighing those conclusions.'" Willey v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2012 WY 144, ¶ 20, 288 P.3d 418, 427 (Wyo.2012) (quoting Beall v. Sky Blue Enters., Inc., 2012 WY 38, ¶ 28, 271 P.3d 1022, 1034 (Wyo.2012)). Considering the conflicting expert opinions regarding causation and the equivocal evidence of immediate onset of pain, we find Mrs. Stevens' case is materially different than Murray.

[¶ 55] The hearing examiner was not persuaded that Murray should apply to Mrs. Stevens' case, concluding "that Murray is distinguishable in that the injury in the Murray case occurred within 15 or 20 minutes of the work related incident. The onset of Stevens['] hip injury, and specifically her AVN is not so clear cut." We agree with the hearing examiner that Mrs. Stevens' fall and the onset of her AVN are "not so clear cut."

[¶ 56] Because of the complexity of the onset of Mrs. Stevens' AVN, we find Langberg v. State ex rel. Wyoming Workers' Safety & Compensation Division, 2009 WY 39, 203 P.3d 1098 (Wyo.2009) is more applicable. In that case, the claimant injured his left wrist while at work. Id. at ¶ 3, 203 P.3d at 1100. Four months later, he re-injured the same wrist. Id. at ¶ 4, 203 P.3d at 1100. He was diagnosed with Kienbock's disease, and eventually underwent surgery because he was developing avascular necrosis due to the Kienbock's disease. Id. at ¶ 7, 203 P.3d at 1100. Langberg's claim was denied by the Division based on lack of proof of causation. He contested this determination, asserting that his Kienbock's disease was caused by a "single traumatic injury," Id. at ¶ 11, 203 P.3d at 1101, and that proof of lack of medical problems before a work injury and change immediately following the injury was sufficient to prove causation. Id. at ¶ 12, 203 P.3d at 1101. However, Langberg's treating physician's deposition testimony "explained the cause of Kienbock's disease is unknown," and that he "found no significance in the fact that Langberg had no wrist problems prior to his work injuries." Id. at ¶¶ 13-14, 203 P.3d at 1101-02.

[¶ 57] On appeal we concluded that "[t]he flaw in Langberg's reasoning is that [his own treating physician], an expert in the field and intimately familiar with Langberg's medical condition, effectively testified that Langberg's theory is pure speculation." Id. at ¶ 16, 203 P.3d at 1102.

[¶ 58] Langberg establishes that a claimant's lack of symptoms, followed by a work incident, followed sometime later by symptoms, does not always meet a claimant's causation burden. See Hayes v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2013 WY 96, ¶ 21, 307 P.3d 843, 850 (Wyo.2013) (citing Jacobs, 2013 WY 62, ¶¶ 19-25, 301 P.3d at 145-48) ("[T]he temporal relationship between [claimant's] pain and the workplace injury, i.e., his pain started when antibiotics were used to treat the infection from his work injury, was insufficient to establish a causal link.").

[¶ 59] Langberg also stands for the proposition that a hearing examiner may rely on expert medical testimony regarding causation to negate a claimant's speculative theory of causation. Id. at ¶ 21, 307 P.3d at 850. In Mrs. Stevens' case, the hearing examiner relied on Dr. Newton's expert medical testimony rather than the speculative post-traumatic theory provided by Mrs. Stevens and her own expert, Dr. Rork. The hearing examiner relied on Dr. Newton's four bases for concluding Mrs. Stevens' AVN was not caused by her fall at work: 1) no immediate, documented pain; 2) the AVN developed too quickly for traumatic AVN; 3) she did not suffer from a fracture or dislocation typical of AVN; and 4) a traumatic injury to one hip causing bilateral systemic AVN is improbable. Dr. Rork only speculated that Stevens had suffered some sort of subluxation resulting in AVN while Dr. Newton provided comprehensive evidence to a reasonable degree of medical probability that Mrs. Stevens' fall did not cause her AVN. "[S]peculative medical testimony is insufficient to satisfy a claimant's burden of proof." Anastos v. Gen. Chem. Soda Ash, 2005 WY 122, ¶ 21, 120 P.3d 658, 666 (Wyo.2005) (citing Frazier v. State ex rel. Wyo. Workers' Safety & Comp. Div., 997 P.2d 487, 490 (Wyo.2000)); see also Corman v. State ex rel. Wyo. Workers' Comp. Div., 909 P.2d 966, 972 (Wyo.1996) ("A claimant cannot prevail if factors necessary to prove his claim are left to conjecture.").

[¶ 60] Our conclusion in Langberg that the mere absence of evidence of disease prior to the work-related injury and the presence of the disease afterwards was not sufficient to establish the causal link, is equally applicable to Mrs. Stevens' case, and we find no error in the hearing officer's conclusions of law. See Langberg, 2009 WY 39, ¶ 12, 203 P.3d at 1101.

CONCLUSION

[¶ 61] The OAH's findings of fact and conclusions of law are supported by substantial evidence and are in accordance with the law. Therefore, we affirm the district court's order which affirmed the OAH's findings and conclusions.