Citation Nr: 21022655 Decision Date: 04/16/21 Archive Date: 04/16/21 DOCKET NO. 16-23 341 DATE: April 16, 2021 ORDER Entitlement to service connection for left knee disability (osteoarthritis), to include as secondary to service-connected right hip degenerative joint disease is denied. FINDING OF FACT The preponderance of the evidence is against finding that left knee disability (osteoarthritis) began during active service, or is otherwise related to an in-service injury or disease. Nor is it secondary to service-connected right hip degenerative joint disease. CONCLUSION OF LAW The criteria for service connection for left knee disability (osteoarthritis) are not met. 38 U.S.C. §§ 1110, 1131, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.309, 3.310. REASONS AND BASES FOR FINDING AND CONCLUSION The Veteran served on active duty in the Air Force as a medical doctor from July 1991 to July 1995. This matter comes to the Board of Veterans’ Appeals (Board) from a decision of the Agency of Original Jurisdiction (AOJ). In January 2005, the AOJ issued a rating decision that denied the Veteran’s claim for service connection for left knee osteoarthritis. The Veteran timely disagreed in a February 2015 Notice of Disagreement (NOD) and perfected his appeal in a May 2016 VA Form 9. In November 2018, the Board remanded the Veteran’s claim for another medical opinion from the VA examiner who conducted his November 2014 disability examination (addendum opinion). In October 2019, the VA obtained an addendum opinion. Then, in July 2020, the AOJ re-adjudicated the claim. The Veteran’s entitlement claim for left knee osteoarthritis was denied. In October 2020, the Veteran’s case was returned to the Board. 1. Entitlement to service connection for left knee disability (osteoarthritis). The Veteran contends his left knee osteoarthritis (left knee disability) was caused by his service-connected hip right hip degenerative joint disease (DJD). In the alternative, he contends his current left knee disability was aggravated by his right hip DJD. See February 2015 NOD. Even though the Veteran has repeatedly asserted that his left knee disability is secondary to his service-connected right hip DJD, the questions for the Board are whether there is sufficient evidence to find his left knee disability is related to his service or secondary to a service-connected disability. For the reasons discussed below, the Board concludes that the evidence does not supports a grant of service connection on a direct or secondary basis. Entitlement to service connection requires a Veteran to provide evidence of three elements: (1) a current disability; (2) in-service incurrence or aggravation of a disease or injury; and (3) a causal relationship or nexus between the current disability and the disease or injury incurred or aggravated during active service. 38 U.S.C. § 1131; 38 C.F.R. § 3.303(a); Shedden v. Principi, 381 F.3d 1163, 1166-67 (2007). A Veteran may also establish service connection on a secondary basis for a disability which is proximately due to or the result of a service-connected disease or injury. 38 C.F.R. § 3.310(a). Or for any increase in the severity of a nonservice-connected disease or injury that is proximately due to or the result of a service-connected disease or injury, and not due to the natural progression of the nonservice-connected disease. 38 C.F.R. § 3.310(b). Another way a Veteran can establish service connection is by satisfying the test for disability compensation for chronic diseases set forth in 38 C.F.R. § 3.303(b). Walker v. Shinseki, 708 F.3d 1331, 1334 (2013). To satisfy that test the Veteran must (1) have a chronic disease listed under § 3.309(a) and (2) that disease must have been “shown in service.” Id. at 1335. As to (1), arthritis is listed under § 3.309(a). As to (2), to be “shown in service” requires a combination of manifestations sufficient to identify the disease entity and “sufficient observation to establish chronicity at the time.” Walker, 708 F.3d at 1335. If the Veteran satisfies the test for disability compensation for chronic diseases in 38 C.F.R. § 3.303(b), the Veteran is relieved of the requirement to show a causal relationship between the condition in service and the condition for which disability is sought. Walker, 708 F.3d at 1335. Entitlement to service connection under 38 C.F.R. § 3.310(a) or (b) requires evidence of three elements: (1) evidence of a current disability that is not service-connected; (2) evidence of a service-connected disability; and, (3) evidence of nexus establishing a connection between the service-connected disability and the current disability. 38 C.F.R. § 3.310. In order to prevail on a claim for benefits, the Veteran need only demonstrate there is an approximate balance of positive and negative evidence. Gilbert v. Derwinski, 1 Vet. App. 49, 54 (1990). This is because the Veteran is entitled to the “benefit of the doubt” when the evidence is approximately balanced. Id. at 53. Beginning with the Veteran’s service, his entrance examination into active duty service does not note any left knee conditions. Part of that examination included a questionnaire wherein the Veteran was free to report any observations related to medical conditions: He did not note any joint problems. He noted a lot of other conditions, like sinusitis, ruptured hernia, case sickness. See March 1991 Report of Medical Examination and Report of Medical History. During an in-service exercise evaluation, the Veteran reported complaints of knee pain when running. The medical professional who evaluated his reports noted he recently began biking and working out with exercise machines again. On physical examination, his range of motion for both knees was within normal limits. The medical professional assessed that he is overweight. See August 12, 1991 Service Treatment Record (STR) by L.K.B. The following month, in September 1991, the Veteran reported to sick-call for complaints of left knee pain from an old basketball injury. The medical professional who evaluated him noted there was some swelling at his knees and diagnosed chronic knee pain. See September 19, 1961, STR. In July 1991, X-ray images of the Veteran’s knees were taken due to complaints of knee pains. The medical professional who evaluated those images noted normal right and left knees. See July 7, 1992, STR by L.A.R., MC. During the Veteran’s second year of active duty service, he underwent a physical examination by G.M., MD, for complaints of hip pains that included an evaluation of the rest of the Veteran’s legs. Dr. G.M. noted that the Veteran’s knees revealed no joint deformities, fluid in the knee, abnormal gait, or swelling around the knees. Dr. G.M. concluded the Veteran’s knees were normal. See October 13, 1992, STR by G.M., MD; October 13, 1992, Letter by G.M., MD, at 1. About a year after leaving service, the Veteran underwent a VA disability examination for his (now service-connected) hip disabilities. During that May 1996 examination, the Veteran’s left and right knees were evaluated. The examiner noted that the Veteran’s left knee range of motion was within normal limits. Also, there was no crepitation (noise made by rubbing together the ends of a fractured bone). The diagnoses that followed included arthritis at the right hip as well as right knee pain. There was no diagnosis of a left knee condition. See May 1996 Disability Evaluation at 2, 3. On October 3, 1996, the Veteran visited a hospital following an injury to his left knee. He reported that, the night before, he was playing basketball and when leaving the court his knee gave out on him. The doctor noted the Veteran’s knee bent outwards when he fell. The doctor examined the Veteran and noted the diagnosis of mediocollateral ligament tear, possible medical meniscal tear, and anterior cruciate ligament tear (ACL, a stabilizing ligament in the knee). See October 4, 1996, Private Medical Record by T.H.M., MD. Several years later, in November 2014, the Veteran underwent a VA disability examination for his left knee disability. The Veteran reported he tore his left ACL after service. He reported he slipped while playing basketball and had ACL reconstructive surgery following that injury. Now, he observes constant pain at his left knee that is aggravated by walking and exercise. Occasionally, the knee gives out. The Veteran also reported flare ups that occur once every other month and last several days. When they occur, they limit his ability to walk and exercise. See November 2014 VA Disability Benefits Questionnaire (DBQ). The examiner noted the diagnosis of osteoarthritis at both knees. He also noted the Veteran had a left knee ACL and meniscal tear in 1998 or 1999. The examiner also noted the Veteran’s left knee conditions cause functional impairment by limiting his ability to walk and exercise. Id. at 1, 2. Then, the examiner opined that the Veteran’s right knee disability is secondary to the Veteran’s service-connected disabilities. The examiner explained that his hip disabilities caused him to develop an altered gait which caused repetitive strain and injury to the knee. See November 2014 VA Medical Opinion at 1. After considering the effects of an altered gait on the Veteran’s right knee, the examiner concluded the Veteran’s basketball injury caused his left knee arthritis. The examiner explained that the type of injury he incurred is likely to cause arthritis and problems to the motion of the knee. The Veteran noted earlier in the exam that there was no evidence of a left knee condition before the injury and during service. The examiner also concluded that his hip disabilities did not contribute much to the severity of the Veteran’s left knee arthritis. Id. In February 2015, the VA received a statement from the Veteran wherein he expressed a belief that his service-connected right hip disability caused his left knee disability. He explained that, due to his right hip disability, he did not exercise for a long time. Then, in 1996, he tried to start exercising. But because he had not exercised for a while, his legs were weak. Due to his weak legs he wound up getting an injury, resulting in a torn ACL. See February 2015 NOD at 2. He went on to explain that his service-connected right hip disability aggravated his left knee disability. He explained that his right hip disability caused him to rely on his left leg so much that it increased the severity of his left knee arthritis. Id. Later, in November 2018, the Board found the VA examiner’s opinion to be inadequate because he did not provide a clear rationale for secondary service connection. So, the Veteran’s claim was remanded for another opinion by that examiner. See November 2018 Board Remand at 5. In June 2019, the Veteran visited with a private doctor, S.M.M., MD, who specializes in sports medicine. Dr. S.M.M. noted the Veteran has been suffering from left knee pains since 1996 (after service). He adds that the Veteran was already suffering from right hip arthritis around 1996, but he tried to stay active as part of his recovery from ACL reconstruction surgery. Dr. S.M.M. noted he reviewed X-ray images of the Veteran’s left knee and noticed severe arthritis. See June 2019 Private Medical Record by S.M.M., MD. at 1, 4. Dr. S.M.M. noted the diagnosis of left knee post-traumatic osteoarthritis. He also noted “it is reasonable to attribute the condition of his knee to the years of dealing with severe debilitation of from [his service-connected right hip disability].” Id. Dr. S.M.M. did not add any explanation for his conclusion. In September 2019, the VA received a statement from the Veteran wherein he explained that he does not usually seek medical attention for his left knee disability. He explained that, because he is a doctor, he is capable of treating his left knee on his own. He added that he observes constant pain at his left knee. See September 2019 Statement in Support of Claim. In October 2019, VA received an addendum medical opinion from the same examiner who prepared the November 2014 opinion. The examiner had been asked to discuss the Veteran’s visits to sick-call during service. Consideration of those visits did not change his opinion. The examiner indicated that, even though his STRs note a complaint of left knee swelling (in August 1991) and another visit for instability (in September 1991), his STRs did not note a left knee condition. See October 2019 Addendum Opinion at 2-3. The examiner added that the Veteran currently has the same condition in both knees, which was noted around the time the Veteran had a basketball injury. Id. The examiner indicated the Veteran’s current left knee disability is more likely related to his basketball injury and ACL reconstruction surgery after service. The examiner noted the injury resulted in an ACL and meniscus tear. Also, those injuries were treated with a surgical procedure, in particular ACL reconstruction. He explained that procedure oftentimes causes the early development of arthritis. Id. After the examiner concluded that the Veteran’s left knee disability was caused by his basketball injury, the examiner opined on that the Veteran’s left knee disability was not aggravated by his service-connected right hip DJD. He reiterated that ACL reconstructive surgery can cause arthritis. But also added that the surgical procedure results in changes to the motion of the knee, which is complicated by factors unique to the individual, like genetics, age. Id. The examiner added that, because the speed of the development of arthritis caused by ACL reconstruction surgery is unique to each person, he is unable to opine on the precise degree of deterioration his service-connected right hip DJD may have added to his left knee disability. Although he could not determine the precise degree, he concluded the Veteran’s right hip DJD did not aggravate the knee beyond its natural progression. Id. A. Entitlement to service connection on a direct basis. Turning to the Veteran’s claim for disability compensation, the first question is whether the Veteran has established entitlement to service connection under 38 C.F.R. § 3.303. That is, on a direct basis. To answer that question, the first issue is whether the Veteran has a current disability. The Veteran has been diagnosed with left knee osteoarthritis during the appeal period. See November 2014 VA DBQ at 2. Thus, the record reflects a diagnosed left knee disability. The next issue is whether the Veteran’s left knee disability began in or was incurred during service, to include an in-service injury. The Veteran’s STRs noting complaints of left knee pains weigh in favor of finding an in-service incurrence. Generally, reports to medical providers in the course of obtaining medical treatment are viewed as reliable. Here, his STRS show two complaints of left knee pain associated with physical activity during service: one associated with running, the other associated with a basketball injury. Even though additional testing on the knee showed it was normal, his reports remain probative evidence of left knee pains during service. So, they were afforded some, but not significant, weight towards an in-service incurrence. See August 12, 1991, and September 19, 1961, STRs. As to the basketball injury, the Board finds the Veteran’s report credible even though he did not provide much detail about it. As previously noted, reports to medical providers in the course of obtaining medical treatment are generally viewed as reliable. In this case, the Veteran was serving as a military doctor when he reported to sick-call. So, he understands the importance of providing an accurate account of events he believes are related to his reason for seeking medical attention. As a result, the Board finds his report of a basketball injury credible and assigned it significant weight towards establishing an in-service injury. The October 1992 physical examination by Dr. G.R.M. weighs against finding an in-service incurrence. Even though his evaluation was focused mostly on the Veteran’s complaints of pain at his hips, the record reflects he also evaluated whether there were other leg conditions, to include at the left knee: He concluded his left knee was normal. Because the evaluation was conducted around the time the Veteran began reporting pain and appears to have been aimed at investigating the extent of the medical problems associated with his legs, the Board finds it credible evidence there was no left knee condition at that point in time. See October 13, 1992, STR and Letter by G.R.M., MD. Dr. G.R.M.’s findings are supported by the July 1992 X-ray report in his STRs, which noted a normal left knee. Because two medical professionals that evaluated the Veteran’s left knee around the time the he reported pains and an injury agree it was normal, the probative value of Dr. G.R.M.’s opinion was assigned great weight against an in-service incurrence. The Board notes that a search of the record did not reveal lay assertions by the Veteran indicating his left knee disability began during service. Neither did he provide observations of a left knee disability during service or symptoms that continued since service. The Board recognizes that the absence of evidence does not weigh against his claim. But, without more, there was no indication the Veteran observed knee pains or other symptoms of a left knee disability following Dr. G.R.M.’s evaluation. In this case, the evidence weighs in favor of finding he had a basketball injury early in his active duty service. He provided competent and credible evidence as to its occurrence and his STRs support his statement. Although the Board finds he had an in-service injury, the evidence weighs against finding his left knee disability began during service. His complaints of pains associated with that basketball injuries led to X-ray imaging that provides reliable evidence he did not have a left knee condition at that time. Also, a medical doctor evaluated that knee when investigating the extent of the Veteran’s reports of leg pains: He also concluded the Veteran’s left knee was normal. Their conclusions are more probative towards the issue of an in-service incurrence. So, doubt on this issue could not be resolved in the Veteran’s favor. Gilbert, 1 Vet. App. at 54. The next issue is whether there is a nexus between the Veteran’s left knee disability and his active service. The Board recognizes the Veteran is a medical doctor who is competent to diagnose left knee arthritis; however, his statements as to its presence were of little probative value. That is because a valid diagnosis of arthritis must be confirmed by X-ray imaging. 38 C.F.R. § 4.17a, Diagnostic Code 5003, Degenerative Arthritis. In this case, the X-ray reports in his STRs note he has normal knees, which indicates he did not have arthritis during service. But, his STRs noting left knee pain remain competent evidence that support a later diagnosis. Jandreau v. Nicholson, 492 F.3d 1372, 1377 (2007). The Veteran’s private doctor, Dr. S.M.M. did not consider the Veteran’s statements when he opined on the cause of the Veteran’s left knee disability. Nor does the record associated with Dr. S.M.M.’s opinion indicate he considered the Veteran’s service when forming his opinion. See June 2019 Private Medical Record by S.M.M., MD. at 1, 4. So, it is not apparent to the Board if he was informed of the relevant details of the Veteran’s past medical history when rendering his opinion. Nievez-Rodriguez v. Peake, 22 Vet. App. 295, 301 (2006). Considering he neither provided a reasoned explanation for his opinion it diminished its probative value. Id. More importantly, because he did not consider or discuss service-connection on a direct basis, the Board finds the opinion had not relevance on this issue. So, the Board did not assign his opinion any probative weight towards a nexus. Id. The VA examiner who prepared the October 2019 medical opinion considered the Veteran’s complaints of pain during service when rendering his conclusion: He opined that the Veteran’s current left knee disability is not related to it. See VA Medical Opinion at 2. The examiner also considered his personal examination of the Veteran and the evidence of record. So, the Board finds the examiner was informed of the relevant details of the Veteran’s past medical history when rendering his opinion. Nievez-Rodriguez, 22 Vet. App. at 301. The VA examiner indicated that, even though there were complaints of knee pains during service, they did not show a conclusive determination of a left knee condition or disability. He also acknowledged that the Veteran has a current left knee disability but attributed it to events that occurred after service. He explained the surgery that followed his 1998/1999 basketball injury can cause his particular disability. Also, that it probably caused it. The Board finds the explanation sufficient to evaluate whether the information he relied on connects to his conclusion. Id. Although the opinion has significant probative value by itself, the weight assigned to it was enhanced by supporting medical evidence in the record. The examiner’s opinion is supported by the findings in the July 1992 X-ray report and October 1992 physical evaluation by Dr. G.R.M. As to Dr. G.R.M.’s finding of a normal left knee, it post-dated the STRs noting a basketball injury and complaints of left knee pain. That supports the portion of the October 2019 opinion that his STRs do not note a left knee condition. As to the X-ray report, it also post-dated the STRs noting a basketball injury and complaints of left knee pain. Also, X-ray imaging is capable of detecting arthritis. Because it did not, the report confirms he had not developed his left knee disability at that time. That supports the portion of the October 2019 opinion that he did not have a left knee condition during service. Since there is medical evidence that supports the October 2019 opinion, it was assigned great weight against a nexus. If there is a question as to the development of his left knee disability for the period between Dr. G.R.M.’s evaluation and within one year following service, the May 1996 VA disability examination weighs against finding it did. The examiner’s evaluation of the Veteran’s knees captured the state of his left knee at that time. So, it is medical evidence that is relevant to whether or not the Veteran had developed his left knee disability by then. Even though the examiner did not discuss the presence of arthritis, the notes associated with his evaluation provide some, but not significant weight, against finding the Veteran had his left knee disability at that time. See May 1996 Disability Evaluation at 2, 3. Considering the examiner’s evaluation investigated the presence of a left knee condition, the Board finds it likely that he would have noted one, if discovered. Since he did not, the Board finds it credible evidence the Veteran did not have a left knee disability at that time. But because it was not accompanied by X-ray imaging that would have confirmed whether or not the Veteran had started to develop arthritis, the evaluation was assigned some, but not significant, weight against a nexus. In this case, the evidence is not approximately balanced on this issue of a nexus. Although the Veteran’s private doctor provided an own, the deficiencies in it led to finding it lacked probative value on this issue. So, the decision was based on the highly probative October 2019 VA medical opinion, which concluded the Veteran’s left knee disability is not related to his service. Since that opinion was supported by other medical evidence in the record, doubt on this issue could not be resolved in his favor. Gilbert, 1 Vet. App. at 54. As a result, the Board finds there is no nexus between the Veteran’s left knee disability and his service. Since the Veteran has not established a nexus nor an in-service incurrence, he has not established entitlement to service connection under 38 C.F.R. § 3.303. B. Entitlement to service-connection on a secondary basis. The next question is whether the Veteran has established entitlement to service connection under 38 C.F.R. § 3.310(a) or (b). That is, on a secondary basis. To answer that question, the first issue is whether the Veteran has a service-connected disability. The record reflects he is service connected for eight disabilities, to include degenerative joint disease (DJD) at the left and right hips. Also, he has asserted his left knee disability is secondary to his service-connected right hip DJD (right hip disability). The Board notes that the Veteran has not asserted his left knee disability is due to any other service-connected disability. And a search of the record did not raise the inference of a claim for service connection under 38 C.F.R. § 3.310 based on any other service-connected disability. So, his right hip disability is the only service-connected disability the is relevant to the discussion. The next issue is whether the Veteran’s left knee disability was proximately caused by his service-connected right hip disability. The Veteran’s medical opinion on this issue was considered. First, the Veteran has personal knowledge of events that occurred around the time he suffered a significant injury, like a torn ACL. So, he is competent to report it. Layno v. Brown, 6 Vet. App. 465, 469 (1994). Second, he is a medical doctor; therefore, he is qualified to opine on the cause of his injury. Here, the Veteran has opined that his service-connected right hip disability led to a chain of events that, eventually, led to the injury related to his left knee disability. See February 2015 NOD at 2. Holding his opinion to the same standards as any other medical opinion, the Board finds it inadequate. That is because he did not consider all the relevant details relating to his left knee disability when rendering his conclusion. Nievez-Rodriguez, 22 Vet. App. at 301. Specifically, the Veteran did not address whether or not the ACL reconstruction surgery that followed his injury caused or aggravated his left knee disability, as was asserted in opinions by a VA examiner. See November 2014 VA Medical Opinion at 1,2; October 2019 VA Medical Opinion at 2, 3. If the Veteran’s opinion was provided by another private medical professional, the deficiency would result in assigning the opinion little to no probative value. Because consideration of the Veteran’s ACL reconstruction surgery is important to an informed understanding of his left knee disability, the Board did not assign his opinion any probative weight. Nievez-Rodriguez, 22 Vet. App. at 301. Similarly, it is not apparent to the Board that Dr. S.M.M. was informed of all the relevant details of the Veteran’s past medical history when he rendered his opinion. Id. As noted before, it is not apparent if he considered the Veteran’s service when rendering his opinion. Although he did not opine it was caused by his service, it is not clear to the Board whether his opinion would have been different if he had. Because the opinion also lacks a rationale, the Board did not assign the opinion any probative weight. Id. The October 2019 VA medical opinion weighed strongly against finding causation. Although the examiner did not provide a separate discussion on this issue, it is apparent to the Board that, when reading his opinion as a whole, he concluded the Veteran’s service-connected hip disability did not cause his left knee disability. Monzingo v. Shinseki, 26 Vet. App. 97, 106 (2012) (explaining that the Court must review an examination report “as a whole” to determine whether the Board clearly erred in assessing the adequacy of the report). The examiner clearly concluded that the ACL reconstruction surgery that followed his 1998/1999 basketball injury caused his left knee disability. The examiner consistently stated that the Veteran’s left knee disability was caused by his ACL reconstruction surgery even when discussing whether it was secondary to his service-connected right hip disability. See November 2014 VA Medical opinion at 1; October 2019 VA Medical Opinion at 2, 3. So, after reading his opinion as a whole, it is apparent to the Board that the examiner did not see a causal link between the Veteran’s right hip disability and his left knee disability. Monzingo, 26 Vet. App. at 106. Because his reasons for that conclusion can be found in the October 2019 opinion, the Board finds it is adequate to evaluate his opinion on this issue. It is apparent to the Board that the examiner did not find the Veteran’s left knee disability was caused by an altered gait brought caused by his service-connected right hip disability. He acknowledged the validity of an altered gait theory of causation when he opined on the Veteran’s (now service-connected) right knee disability. See November 2014 VA Medical opinion at 1. Considering the examiner opined on the Veteran’s left knee disability in the same opinion and did not discuss that theory, the Board finds he concluded it did not apply to the left knee. Id. The Board’s finding is supported by the absence of a discussion of the altered gait theory of causation in the examiner’s October 2019 VA Medical Opinion. See VA Medical Opinion at 2, 3. Because he discussed that theory in the November 2014 opinion, the Board concludes he knew of the theory when rendering his later opinion. Because he chose not to discuss it, the Board concludes it is not likely he thought it applied. The examiner explained that the Veteran’s ACL reconstruction surgery is the likely cause of his left knee disability. He also attributed changes in the mechanics of the Veteran’s knee to his ACL reconstruction surgery. The Board finds his explanation sufficient to evaluate whether the information he relied on connects to his conclusion. Nievez-Rodriguez, 22 Vet. App. at 301. Even though the examiner’s opinion was significant probative weight against causation on its own, the weight assigned to it was enhanced by supporting medical evidence in the record. The examiner’s opinion is supported by the findings in the October 1992 physical evaluation by Dr. G.R.M. and the May 1996 VA disability evaluation. Both of them show that the Veteran’s service-connected right hip disability had not resulted in an altered gait during that period of time. See October 13, 1992, Letter by G.R.M., MD; May 1996 Disability Evaluation at 2, 3. Although it does not address the period of time after 1996, it is some, but not significant, evidence that supports the a portion of the October 2019 VA medical opinion. That is, the portion that concludes the Veteran’s right hip disability did not cause his left knee disability. The Board recognizes the November 2014 opinion was found to be insufficient to decide the claim; however, that finding was because the examiner appeared to combine his opinion as to direct and secondary service connection. The parts of his opinion that have not been determined to be inadequate still have probative value. So, his opinion on the effects of ACL reconstruction surgery remained competent and credible evidence that can support his second opinion. Monzingo, 26 Vet. App. at 24. As to the issue of causation, the Board finds the evidence is not approximately balanced. Although the Veteran and his private doctor provided their own opinions, the deficiencies in each opinion led to finding that they lacked probative value. So, the decision was based on the highly probative October 2019 VA medical opinion, which clearly stated that the Veteran’s left knee disability was not caused by his service-connected right knee disability. So, doubt could not be resolved in the Veteran’s favor. Gilbert, 1 Vet. App. at 54. Thus, the Veteran has not established entitlement to service connection under 38 C.F.R. § 3.310(a). The next issue is whether the Veteran’s left knee disability was aggravated by his service-connected right hip disability. The Veteran’s medical opinion on this issue was not considered. His opinion as to aggravation is found within the same opinion concerning causation. That opinion was found be inadequate because it is unclear if he considered all the relevant details related to his left knee disability when rendering his conclusion. The finding is relevant here because he has not explained if his ACL reconstruction surgery had any effect on the aggravation of his left knee disability, which is important to an informed understanding of his disability. So, the Board did not assign his opinion any probative weight. Nievez-Rodriguez, 22 Vet. App. at 301. Likewise, Dr. S.M.M.’s opinion was found inadequate because it is unclear if he considered the Veteran’s service and his opinion lacked a rationale. The Board also notes, it is not clear if he was asserting an opinion as to aggravation. See June 2019 Opinion by S.M.M., MD, at 4. So, the Board did not assign his opinion any probative weight on this issue. The October 2019 medical opinion weighs strongly against finding his left knee disability was aggravated by his service-connected right hip disability. The examiner acknowledged that the Veteran’s right hip disability can alter his gait but explained the mechanics of the left knee were already altered by his ACL reconstruction surgery. He also indicated that, even though he could not quantify the precise degree the Veteran’s right hip disability effected his left knee disability, it did not aggravate it beyond its natural progression. See Medical Opinion at 2, 3. His explanation was sufficient to evaluate whether the information he relied on connects to his conclusion. Nievez-Rodriguez, 22 Vet. App. at 301. Considering he had the opportunity to re-evaluate his opinion and came to the same conclusion, the Board assigned it great weight. As to the issue of aggravation, the Board finds the evidence is not approximately balanced. Although the Veteran and his private doctor provided their own opinions, they were not assigned any probative value. Thus, the decision was based on the highly probative October 2019 VA medical opinion, which concluded that the Veteran’s left knee disability was not aggravated service-connected right knee disability. So, doubt could not be resolved in the Veteran’s favor. Gilbert, 1 Vet. App. at 54. As a result, the Veteran has not established entitlement to service connection under 38 C.F.R. § 3.310(b). C. Entitlement to service connection based on a chronicity and continuity of symptomatology. The next question is whether the Veteran has established entitlement to service connection under 38 C.F.R. § 3.303(b). That is, based on chronicity or continuity of symptomatology. The first issue is whether the Veteran has a chronic disability under VA regulations. The Veteran’s diagnosed left knee osteoarthritis is a disability that falls within 38 C.F.R. § 3.309(a). Thus, the record reflects the Veteran has a chronic disability. Although the record reflects a diagnosed chronic disability, it was not shown in or noted in service. As explained above, there is no evidence in the Veteran’s STRs that support finding he had a diagnosis of left knee arthritis during service. See July 7, 1992, STR. Nor within one year after leaving service. See May 1996 Disability Evaluation at 2, 3. If there is any question about the sufficiency of the X-ray conducted during service and the May 1996 disability examination, the October 2019 VA medical opinion is additional medical evidence that weighed against a finding of chronicity during or within the year after leaving service. This examiner acknowledged and considered the Veteran’s diagnosed chronic disability and indicated it is not related to his service. See VA Medical Opinion at 1, 2. So, the Board assigned the opinion significant weight against a finding of chronicity at the time of service. In this case, the evidence is not approximately balanced in favor of finding the Veteran’s chronic disability was shown in service. There is not enough evidence of a reliable diagnosis of a chronic disability during service. Walker, 708 F.3d at 1335. So, doubt could not be resolved in the Veteran’s favor. Gilbert, 1 Vet. App. at 54. As to continuity of symptomatology, the Veteran has not asserted he observed continuous symptoms of a left knee pain or arthritis since service. The Board recognizes his September 2019 statement reporting he observes constant pain at his left knee. See Statement in Support of Claim. Considering he did not report constant pain during his October 1992 physical examination while in service, nor during his May 1996 VA disability evaluation, there is no basis on which the Board can interpret his statement to imply he has observed constant pain since service. See October 13, 1992, STR; Disability Evaluation at 2, 3. So, that statement is credible towards finding he observed pain during the appeal period, but not during service or within the year after leaving service. Because the Board has also found a chronic disability was not shown during service or within one year after service, consideration of service-connection based on continuity of symptomatology is not warranted. In sum, the Veteran has not established entitlement to service connection under 38 C.F.R. §§ 3.303 or 3.10. Also, the Veteran has not raised any other issues nor have any other issues been reasonably raised by the record. Robinson v. Peake, 21 Vet. App. 545, 552-54 (2008) (holding the Board is not required to address issues unless specifically raised by the claimant or reasonably raised by the record). The Board regrets a more favorable decision could not be reached in the Veteran’s case. DAVID L. WIGHT Veterans Law Judge Board of Veterans’ Appeals Attorney for the Board Dean, Michael S. The Board’s decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.