To receive workers' compensation benefits, the claimant bears the burden of proving not only that the accident arose out of and in the course of employment, but also that the alleged injury was caused by the accident. ${ }^{34}$ In other words, the claimant must establish a causal connection between the accident and the injury. ${ }^{35}$ Section 287.020.3(1), RSMo, provides that an injury by accident is compensable only if the accident was the prevailing factor in causing both the resulting medical condition and disability and defines "the prevailing factor" as the primary factor, in relation to any other factor, causing both the resulting medical condition and the disability. Medical causation must be established by scientific or medical evidence "showing the cause and effect relationship between the complained of condition and the asserted cause."36 When medical theories conflict, deciding which to accept is an issue reserved for the determination of the fact finder. ${ }^{37}$
In addition, the fact finder may accept only part of the testimony of a medical expert and reject the remainder of it. ${ }^{38}$ Where there are conflicting medical opinions, the fact finder may reject all or part of one party's expert testimony that it does not consider credible and accept as true the contrary testimony given by the other litigant's expert. ${ }^{39}$
This case is similar to Tillotson v. St. Joseph Medical Center, 347 S.W.3d 511 (Mo.App. 2011). In both cases, the employees had pre-existing conditions affecting their injured knee, suffered work-related injuries to the affected knee, and required total knee replacements to cure and relieve them from the effects of their respective, work-related injury. The Missouri Appeals Court held that once the prevailing factor test is applied to the question as to whether an employee has a compensable injury, an employer is obligated to provide "such medical, surgical, chiropractic and hospital treatment, including nursing, custodial, ambulance and medicine, as may reasonably be required after the injury or disability, to cure and relieve the effects of the injury." 40 "The 2005 amendments to The Workers' Compensation Law did not, however,
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[^0]: ${ }^{34} Landers v. Chrysler Corp., 963 S.W.2d 275, 279 (Mo.App. 1997).
{ }^{35}$ McDermott v. City of Northwoods Police Dep't, 103 S.W.3d 134, 138 (Mo.App. 2002).
${ }^{36} Williams v. DePaul Health Center, 996 S.W.2d 619, 631 (Mo.App. 1999).
{ }^{37} Hawkins v. Emerson Elec. Co., 676 S.W.2d 872, 977 (Mo. App. 1984).
{ }^{38} Cole v. Best Motor Lines, 303 S.W.2d 170, 174 (Mo. App. 1957).
{ }^{39}$ Webber v. Chrysler Corp., 826 S.W.2d 51, 54 (Mo. App. 1992); Hutchinson v. Tri State Motor Transit Co., 721 S.W.2d 158, 163 (Mo. App. 1986).
${ }^{40}$ Tillotson v. St. Joseph Medical Center, 347 S.W.3d 511, 518. See also Section 287.140.1, RSMo.
incorporate a 'prevailing factor' test into the determination of medical care and treatment required to be afforded for a compensable injury by Section 287.140.1." ${ }^{41}$
In this case, it is uncontested that claimant had pre-existing conditions that affected his right knee. He had three arthroscopic surgeries on his right knee prior to his work-related accident and injury on January 9, 2011. These surgeries were performed on December 28, 1995, January 21, 1997, and April 24, 2003. The first and third surgeries were to repair meniscal tears and the second surgery was to perform a bone graft to repair bone that had not properly healed after the first surgery.
During the December 28, 1995 surgery, the orthopedic surgeon noted that "the ACL appeared to be intact visually." ${ }^{42} During the January 21, 1997 surgery, the orthopedic surgeon noted that " [t]$ he anterior cruciate ligament appeared slightly attenuated but was intact to inspection and probing." ${ }^{43}$ During the April 24, 2003 surgery, the orthopedic surgeon noted that although claimant "demonstrated a partial anterior cruciate ligament tear . . . he demonstrated good stability under anesthesia as well as under visualization with a drawer test." ${ }^{44}$
At trial, claimant testified credibly that following each of these prior surgeries, although he continued to have symptoms in his right knee, he was able to return to his regular duties with the Kirksville Fire Department without any physical restrictions after he was released from medical care. Claimant further testified that prior to January 9, 2011, he never saw a doctor for or received treatment for his right anterior cruciate ligament, that no doctor ever told him that he needed treatment or surgery for his right anterior cruciate ligament, and that after each of his three prior right knee surgeries, none of those surgeons told him that he had a problem with his right anterior cruciate ligament. After Dr. Tarbox released claimant following the April 2003 surgery, but before the January 2011 injury, claimant never sought or received any type of medical care or treatment for his right knee.
Both medical experts agree that claimant would benefit from a right, total knee replacement, but they disagree on what has caused the need for that treatment.
Dr. Dwight Woiteshek examined claimant on September 21, 2011; his examination of claimant's right knee showed that claimant had pain, tenderness and a small effusion. The Lachman test, Drawer sign, and pivot shift tests were all slightly positive. Dr. Woiteshek also noted mild patellofemoral mistracking, a positive Apley distraction test, a positive Apley compression test, and a positive patellofemoral grind test. Dr. Woiteshek testified that these positive findings told him that claimant's anterior cruciate ligament was not functioning. ${ }^{45}$
Based upon the histories that were provided to Dr. Woiteshek, together with his findings on examination, the doctor diagnosed a traumatic internal derangement of claimant's right knee with subsequent high grade partial tear versus complete tear of the anterior cruciate ligament, together with osteochondral injuries of the posterior medial femoral condyle and anterior lateral
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[^0]: ${ }^{41} Id. at 519 .
{ }^{42} Claimant's Exh. D.
{ }^{43} Claimant's Exh. E.
{ }^{44} Claimant's Exh. F.
{ }^{45} Claimant's Exh. A, pp. 9-10.
condyle. { }^{46}$ Each of these diagnoses is supported by the radiologist's interpretation of the claimant's February 3, 2011 MRI of the right knee. ${ }^{47}$
Dr. Woiteshek testified that the significance of a "high grade" partial versus complete tear of the ACL means that "the anterior cruciate ligament was really damaged." ${ }^{48}$ Dr. Woiteshek further testified that the osteochondral injuries to the posterior femoral condyle and anterior lateral condyle were "definitely traumatic" in nature and that an osteochondral injury means "an acute injury." Dr. Woiteshek was provided with histories of claimant's prior right knee problems, including three arthroscopic surgeries on the knee. These prior histories did not alter Dr. Woiteshek's opinion regarding medical causation
During his deposition, Dr. Woiteshek was asked about the mechanism of claimant's injury in relation to the diagnoses he arrived at. Specifically, he was asked the following by Mr. Link:
Q. When Mr. Maize's deposition was taken, he testified, quote, "There was rock on the concrete curb, and I stepped on it to open the door to the pickup, and my foot slipped out from underneath me, and when it did, my leg kind of went forward and back and I felt a pop in my knee on the inside of my knee," end quote.
Doctor, how, if at all, does that history of Mr. Maize's description of the accident support your diagnoses, your treatment recommendations and your opinions regarding medical causation as they relate to his January 9, 2011 accident?
A. That injury that he had as described in the deposition is a classic injury where you would expect injury to the anterior cruciate ligament, a popping and then the movement of the knee front and back. Those are classic signs of an anterior cruciate ligament tear. ${ }^{49}$
Dr. Woiteshek concluded that claimant's January 9, 2011 accident when he slipped on some rocks and twisted his right knee, was the prevailing factor in causing the high grade versus partial tear of the anterior cruciate ligament, together with osteochondral injuries of the posterior medial femoral condyle and anterior lateral condyle. Dr. Woiteshek further testified that claimant has not yet reached maximum medical improvement and that he needs additional medical treatment, including but not limited to a right total knee replacement; the doctor also testified that the January 9, 2011 accident was the prevailing factor in the cause for the need of this surgery.
Dr. Michael Nogalski examined claimant on March 16, 2011. During that examination, Dr. Nogalski noted that there was a small amount of fluid in the knee and tenderness in the inside portion of the knee rather than the outside along the joint lines. He also noted that range of motion in the right knee was "about 0 to 100 degrees" with pain at end ranges of motion. With respect to the right knee MRI that was performed on February 3, 2011, Dr. Nogalski noted that it
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[^0]: ${ }^{46} Claimant's Exh. A, pp 10-11.
{ }^{47} Claimant's Exh. C.
{ }^{48} Claimant's Exh. A.
{ }^{49}$ Claimant's Exh. A, pp. 16-17.
showed significant chondrosis and bone barrow edema in the medial femoral condyle. Dr. Nogalski could not identify "a suggestion of a new tear or something that was unstable" and felt " $[t]$ he ACL or anterior cruciate ligament was not well visualized."50
Based upon his examination and evaluation of claimant, Dr. Nogalski diagnosed him with a right knee strain, which he felt was related to the January 9, 2011 accident, and degenerative disease, which the doctor did not feel was related to the January 9, 2011 accident. Dr. Nogalski did provide a steroid injection into claimant's right knee, and he indicated that this was reasonable and necessary treatment in relation to his diagnosis of right knee strain. ${ }^{51}$
Dr. Nogalski agrees that a total knee replacement would be a treatment option for the claimant's right knee; however, he attributes the need for that treatment and surgery to claimant's symptoms of osteoarthritis and not to his January 2011 accident.
I find that the testimony and opinions of Dr. Woiteshek are more persuasive and credible on the issue of medical causation than those of Dr. Nogalski. Dr. Woiteshek concluded that claimant's January 9, 2011 accident was the prevailing factor in causing the diagnoses he arrived at (specifically the high grade versus partial tear of the anterior cruciate ligament, together with osteochondral injuries of the posterior medial femoral condyle and anterior lateral condyle.
I find that claimant has met his burden of proof with respect to the issue of medical causation. Claimant experienced an unexpected traumatic event or unusual strain identifiable by time and place of occurrence and producing at the time objective symptoms of an injury caused by a specific event on January 9, 2011; this event was the prevailing factor in causing the resulting medical condition of traumatic internal derangement of claimant's right knee, with corresponding high grade partial versus complete tear of the ACL.