Citation Nr: 21075737 Decision Date: 12/21/21 Archive Date: 12/21/21 DOCKET NO. 13-32 840 DATE: December 21, 2021 ORDER Prior to May 19, 2015, entitlement to a rating in excess of 10 percent for service-connected degenerative joint disease of the left knee (left knee disability) is denied. From May 19, 2015, entitlement to a rating in excess of 40 percent for service-connected left knee disability is denied. From April 20, 2016, entitlement to a rating of 10 percent, but no higher, for instability and subluxation of the left knee is granted. REMANDED Entitlement to service connection for a low back disability, to include as secondary to service-connected left knee disability, is remanded. Entitlement to service connection for a right knee disability, to include as secondary to service-connected left knee disability, is remanded. Entitlement to a total disability rating based on individual unemployability (TDIU) due to service-connected disability is remanded. FINDINGS OF FACT 1. Prior to May 19, 2015, the Veteran's left knee disability has been manifested by pain on motion; but not by ankylosis, instability, or a compensable limitation in flexion or extension. 2. From May 19, 2015, the Veteran's left knee disability, at worst, has been manifested by flexion limited to 70 degrees and extension to 30 degrees; but not by ankylosis. 3. From April 20, 2016, the Veteran's left knee disability has been manifested by slight instability and subluxation. CONCLUSIONS OF LAW 1. Prior to May 19, 2015, the criteria for a rating in excess of 10 percent for service-connected left knee disability have not been met. 38 U.S.C. § 1155; 38 C.F.R. §§ 4.7, 4.71a, Diagnostic Codes 5003, 5010, 5257, 5258, 5259, 5260, 5261. 2. From May 19, 2015, the criteria for a rating in excess of 40 percent for service-connected left knee disability based on limitation of extension have not been met. 38 U.S.C. § 1155; 38 C.F.R. §§ 4.7, 4.71a, Diagnostic Codes 5256, 5260, 5261. 3. From April 20, 2016, the criteria for a 10 percent rating, but no higher, for service-connected left knee disability based on slight instability have been met. 38 U.S.C. § 1155; 38 C.F.R. §§ 4.7, 4.71a, Diagnostic Codes 5257. REASONS AND BASES FOR FINDINGS AND CONCLUSIONS The Veteran had active military service from December 1983 to November 1987. This matter comes before the Board of Veterans' Appeals (Board) on appeal from a July 2011 rating decision of the Department of Veterans Affairs (VA) Regional Office (RO). In August 2017, the Veteran and his fiancée testified before a Board hearing. The transcript of the hearing is of record. In January 2018, the Board remanded the issues on appeal for further evidentiary development. In a January 2021 Board decision, the Board remanded the issues on appeal as there were pertinent SSA records and medical records that were not associated with the file. The Board also determined that an issue of entitlement to a TDIU was raised by the record and thus the issue was added to the appeal. See Rice v. Shinseki, 22 Vet. App. 447, 453, 54 (2009). Since the January 2021 Board remand, SSA records are now associated with the file. Although the Veteran attested that the Spine Center on Battlefield Boulevard was not "at the VA," in the April 2021 VA 21-4142 Authorization for Release of Information form the Veteran indicated that the facility name is "HAMVAMEDCEN Hampton, VA Chesapeake Spine Center Battlefield Blvd." which is the Hampton VAMC. Records from Hampton VAMC are already associated with the file. As the RO substantially complied with the January 2021 Board remand order, the matter has returned to the Board for appellate consideration. Increased Rating Disability evaluations are determined by the application of the facts presented to VA's Schedule for Rating Disabilities (Rating Schedule) at 38 C.F.R. Part 4. The percentage ratings contained in the Rating Schedule represent, as far as can be practicably determined, the average impairment in earning capacity resulting from diseases and injuries incurred or aggravated during military service and the residual conditions in civilian occupations. 38 U.S.C. § 1155; 38 C.F.R. §§ 3.321(a), 4.1. In evaluating the severity of a particular disability, it is essential to consider its history. 38 C.F.R. § 4.1; Peyton v. Derwinski, 1 Vet. App. 282 (1991). Where entitlement to compensation has already been established and an increase in the disability rating is at issue, the present level of disability is of primary importance. Francisco v. Brown, 7 Vet. App. 55, 58 (1994). Higher evaluations may be assigned for separate periods based on the facts found during the appeal period. See Hart v. Nicholson, 21 Vet. App. 505, 509 (2007); see also Fenderson v. West, 12 Vet. App. 119, 126 (1999). This practice is known as staged ratings. When evaluating disabilities of the musculoskeletal system, functional loss due to pain and weakness causing additional disability beyond that reflected on range of motion measurements must be considered. See 38 C.F.R. § 4.40; DeLuca v. Brown, 8 Vet. App. 202 (1995). Consideration must also be given to weakened movement, excess fatigability, and incoordination. 38 C.F.R. § 4.45. The evaluation of the same disability under several diagnostic codes, known as pyramiding, must be avoided; however, separate ratings may be assigned for distinct disabilities resulting from the same injury so long as the symptomatology for one condition is not duplicative of the symptomatology of the other condition. 38 C.F.R. § 4.14; Esteban v. Brown, 6 Vet. App. 259, 262 (1994). Separate ratings under Diagnostic Code 5260, for limitation of flexion of the knee, and Diagnostic Code 5261, for limitation of extension of the knee, may be assigned for disability of the same joint, but only where the criteria for a compensable rating are met under each diagnostic code. VAOGCPREC 9-2004 (2004). Pursuant to Diagnostic Code 5260, a 10 percent rating is warranted for knee flexion limited to 45 degrees. A 20 percent rating is warranted for knee flexion limited to 30 degrees. A maximum 30 percent rating is warranted for knee flexion limited to 15 degrees. 38 C.F.R. § 4.71a, Diagnostic Code 5260. As for extension, pursuant to Diagnostic Code 5261, a 10 percent rating is warranted for knee extension limited to 10 degrees. A 20 percent rating is warranted for knee extension limited to 15 degrees. A 30 percent rating is warranted for knee extension limited to 20 degrees. A 40 percent rating is warranted for knee extension limited to 30 degrees. A maximum 50 percent rating is warranted for knee extension limited to 45 degrees. 38 C.F.R. § 4.71a, Diagnostic Code 5261. Normal knee range of motion is to 140 degrees of flexion and 0 degrees of extension. 38 C.F.R. § 4.71a, Plate II. Diagnostic Code 5256 pertains to ankylosis. 38 C.F.R. § 4.71a, Diagnostic Code 5256. Here, the records do not show that the Veteran has ankylosis at any point in the appeal period and as such Diagnostic Code 5256 is not applicable in this case. Under Diagnostic Code 5258, a 20 percent rating is available for dislocated semilunar cartilage with frequent episodes of locking, pain, and effusion into the joint. Under Diagnostic Code 5259, a 10 percent rating is warranted for removal of semilunar cartilage, symptomatic. 38 C.F.R. § 4.71a, Diagnostic Code 5259. During the pendency of the appeal, the rating criteria for evaluating musculoskeletal disabilities (including patellofemoral pain syndrome and knee instability) under 38 C.F.R. § 4.71a were amended effective February 7, 2021. See 85 Fed. Reg. 230 (Nov. 30, 2020). These amendments revised select diagnostic codes "to ensure that this portion of the rating schedule uses current medical terminology and provides detailed and updated criteria for the evaluation of musculoskeletal disabilities." Id. The Board will consider the claim under the old criteria prior to February 7, 2021 and both the old and new rating criteria from February 7, 2021. The criteria that is more favorable to the Veteran will be applied. Prior to the regulatory change, Diagnostic Code 5257 states a 10 percent rating is warranted for slight recurrent subluxation or lateral instability; a 20 percent rating is warranted for moderate recurrent subluxation or lateral instability; and a 30 percent rating is warranted for severe recurrent subluxation or lateral instability. See 38 C.F.R. § 4.71a, Diagnostic Code 5257 (effective prior to February 7, 2021). After the regulatory change, Diagnostic Code 5257 states a 10 percent rating is warranted for sprain, incomplete ligament tear, or complete ligament tear (repaired, unrepaired, or failed repair) causing persistent instability, without a prescription from a medical provider for an assistive device (e.g., canes, crutches, walker) or bracing for ambulation. A 20 percent rating is warranted for (a) sprain, incomplete ligament tear, or repaired complete ligament tear causing persistent instability, and a medical provider prescribes a brace and/or assistive device (e.g., cane, crutches, walker) for ambulation; (b) unrepaired or failed repair of complete ligament tear causing persistent instability and a medical provider prescribes either an assistive device (e.g., canes, crutches, walker) or bracing for ambulation. A 30 percent rating is warranted for unrepaired or fail repair of complete ligament tear causing persistent instability, and a medical provider prescribes both an assistive device (e.g., canes, crutches, walker) and bracing for ambulation. See 38 C.F.R. § 4.71a, Diagnostic Code 5257 (effective February 7, 2021). The revised Diagnostic Code 5257 also addresses patellar instability. A 10 percent rating is warranted for a diagnosed condition involving the patellofemoral complex with recurrent instability (with or without history of surgical repair) that does not require a prescription from a medical provider for a brace, cane, or walker. A 20 percent rating is warranted for a diagnosed condition involving the patellofemoral complex with recurrent instability after surgical repair that requires a prescription by a medical provider for one of the following: a brace, cane, or walker. A 30 percent rating is warranted for a diagnosed condition involving the patellofemoral complex with recurrent instability after surgical repair that requires a prescription by a medical provider for a brace and either a cane or a walker. 1. Prior to May 19, 2015, entitlement to a rating in excess of 10 percent for service-connected left knee disability is denied. 2. From May 19, 2015, entitlement to a rating in excess of 40 percent for service-connected left knee disability is denied. 3. From April 20, 2016, entitlement to a rating of 10 percent for instability and subluxation of the left knee is granted. At the outset, the Veteran filed a claim for increased rating for his left knee disability in April 2011. Prior to May 19, 2015, the Veteran's left knee disability is rated at 10 percent disabling and 40 percent thereafter. A review of the records shows that the Veteran was afforded VA examinations in June 2011, March 2016, and January 2019. In the June 2011 VA examination, the Veteran endorsed having weakness, stiffness, swelling, giving way, lack of endurance, locking, tenderness, and pain of the left knee. He denied having heat, redness, fatigability, deformity, drainage, effusion, subluxation, or dislocation. He claimed that he has flare ups as often as five times per day that lasts for about three hours. He reported having difficulties with standing and walking. On examination, he was able to flex to 140 degrees and extend to 0 degrees with pain. He was able to perform repetitive range of motion testing with no limitation due to painful motion, fatigue, weakness, or incoordination. His posture was normal, and he walked with a normal gait. He had normal tandem gait. His feet did not reveal any signs of abnormal weight bearing or breakdown, callosities, or any unusual shoe wear pattern. He did not require any assistive device for ambulation. There were no signs of edema, instability, abnormal movement, effusion, weakness, redness, heat, deformity, guarding of movement, malalignment, and drainage. There was no subluxation. There was no evidence of ankylosis. His linear scar on the left knee was not painful on examination. The VA treatment records dated in 2013 shows that although he complained of locking and catching of his left knee, on examination he was noted to have good motion and stability in June 2013, August 2013, and October 2013 VA treatment records. Moreover, the VA treatment records show that he predominantly denied having any falls in 2013. In July 2013, he underwent an arthroscopy of the left knee. He was diagnosed with left knee loose body and chondromalacia. About 12 days later, his active range of motion of the left knee was 3 to 105 degrees. See October 2014 CAPRI. In a May 19, 2015 VA treatment record, he was able to flex to 90 degrees and extend to 30 degrees on active range of motion; and flex to 90 degrees and extend to zero degrees on passive range of motion. See March 2016 CAPRI. In the March 2016 Knee Disability Benefits Questionnaire (DBQ), the Veteran reported that during flare ups he cannot walk or fully extend his knee. He stated that he has difficulty with prolonged walking, kneeling, squatting, and climbing stairs or ladders. On examination, he was able to flex to 70 degrees and extend to 30 degrees with pain. There was evidence of pain with weight bearing. He exhibited evidence of crepitus. He was able to perform repetitive range of motion testing with no additional loss of function or range of motion. During flare ups the examiner determined that due to pain he would have difficulty with kneeling, squatting, and climbing stairs. He exhibited normal muscle strength with no evidence of muscle atrophy. There was no evidence of ankylosis or instability. In an April 2016 VA treatment record, he reported that he has a history of falls and gait instability. See February 2018 CAPRI. In the January 2019 DBQ, he complained of falling as a result of his bilateral knee disability. On examination, he was able to flex to 70 degrees and extend to 30 degrees with pain. There was evidence of pain with weight bearing. He was unable to perform repetitive range of motion testing. As such, the examiner was unable to say without mere speculation on whether his pain, weakness, fatigability, or incoordination significantly limit functional ability with repeated use over a period of time as there is no conceptual or empirical basis for making such a determination without directly observing function under these conditions. Additionally, the examiner was unable to say without mere speculation on whether the Veteran's pain, weakness, fatigability, or incoordination significantly limit functional ability during a flare-up as there is no conceptual or empirical basis for making such a determination without directly observing function under these conditions. He exhibited abnormal muscle strength but no evidence of muscle atrophy. There was no evidence of ankylosis. He was noted to have slight instability and subluxation. He reported that he has frequent episodes of joint locking, but no joint effusion. His scar on the left knee was not painful or unstable on examination. There was objective evidence of pain on passive range of motion testing and when the joint was used in non-weight bearing. Prior to May 19, 2015 Based on the records, the Board finds that the Veteran is not entitled to a rating in excess of 10 percent for a right knee disability under the limitation of motion codes. On physical examination of the Veteran's left knee, he was able to flex, at worst, to 105 degrees and extend, at worst, limited to 3 degrees, which is consistent with a noncompensable rating under Diagnostic Codes 5260 and 5261. These findings do not support a compensable rating under Diagnostic Codes 5260 or 5261 as a 10 percent rating requires limited flexion to 45 degrees and extension to 10 degrees. Considering the Veteran's noncompensable limitation of motion and consistent with his subjective complaints of pain on motion, the Board finds that the Veteran's current 10 percent rating for a left knee disability adequately compensates him for the level of disability shown. The Board acknowledges that VA regulations state that it is the intention to recognize actual painful, unstable, or malaligned joints as entitled to at least the minimum compensable rating for the joint. 38 C.F.R. § 4.59. The Board has considered factors such as function loss caused by weakened movement, excess fatigability, incoordination, and pain on movement. 38 C.F.R. § 4.45. In this case, the Veteran has been assigned at least the minimum compensable rating based on pain, and there is no indication that pain or other factors have ever caused further limitation of motion to such an extent that higher ratings should be assigned. See DeLuca v. Brown, 8 Vet. App. 202 (1995); see also Mitchell v. Shinseki, 25 Vet. App. 32, 44 (2011). As for instability, locking of the knees, and painful scars, the Board finds that despite the Veteran's claim of locking of the left knee, on examination, as evidenced by the June 2011 VA examination and treatment records, he exhibited no objective signs of instability, locking of the left knee, or painful scar. Although the Veteran asserted that his left knee gives out, the Board affords more probative value to the results of the VA examination as the test designed to ascertain instability was normal, and there were no signs of edema, instability, abnormal movement, effusion, weakness, redness, heat, deformity, guarding of movement, malalignment and drainage upon physical examination. Thus, the Board concludes that a rating under Diagnostic Codes 5257 and 5258 is not for application. The Board has considered the holding of English v. Wilkie, 30 Vet. App. 347 (2018) and acknowledges that the Veteran is competent to report having a feeling of being unstable, and that he believes that he has instability in his knees. While a lay person is not automatically less competent to identify knee instability than a medical professional, instability and laxity in a knee joint are symptoms which can be tested and measured, and the Veteran's VA examination have shown that there is no clinically observable instability. There is also no medically supported indication of a functional manifestation of the Veteran's feelings of instability, and therefore the Board does not find that the Veteran's feelings of instability rise to a separate disability that manifests with compensable, functional impairment. From May 19, 2015 Based on the records, the Board finds that the Veteran is not entitled to a rating in excess of 40 percent for left knee disability under the limitation of motion codes. On physical examination of the Veteran's left knee, the Veteran was able to flex, at worst, to 70 degrees and extend, at worst, to 30 degrees, which is consistent with a noncompensable rating under Diagnostic Codes 5260 (flexion) and a 40 percent rating under Diagnostic Code 5261 (extension). These findings do not support a rating in excess of 40 percent under Diagnostic Code 5261 as a 50 percent rating requires limited extension to 45 degrees. As for instability and subluxation of the knees, the Board notes that on April 20, 2016, he reported that he has a history of locking or giving way of the knees. Although the Veteran had no objective evidence of subluxation or instability in the March 2016 VA examination the Board notes that in the January 2019 VA examination the Veteran was noted to have slight instability and subluxation. Additionally, the records show that in an October 2016 VA treatment record it was noted that his knees buckled, and he would fall frequently. See March 2016 CAPRI. Then in a March 2017 VA treatment record, he reported that he fell the prior week as his knee locked up. As such, in the light most favorable to the Veteran, the Board finds that he should be awarded a separate 10 percent rating, but no higher, for his slight instability and subluxation as of April 20, 2016 pursuant to Diagnostic Code 5257 (recurrent subluxation or lateral instability). The evidence does not support a rating for a higher 20 percent rating, as moderate instability and/or subluxation or persistent instability has not been shown. The Veteran also has not ever been found to have a ligament sprain, incomplete ligament tear, or complete ligament tear, and a compensable separate evaluation under the revised version of Diagnostic Code 5257 (2021) is not warranted. He is not entitled to a 20 percent rating under Diagnostic Code 5258 for cartilage semilunar dislocation with frequent episodes of "locking," pain, and effusion into the joint as the records do not show effusion into the joint. Regarding the Veteran's scar on the left knee, the Board notes that in the August 2017 hearing he attested that he has painful scar. However, in the January 2019 DBQ, he denied having painful and/or unstable scar. The Board also notes that he did not complain of having painful and/or unstable scar throughout the treatment records and VA examinations. As such, the Board finds that the Veteran is not entitled to a compensable rating for his scar. REMANDED 4. Entitlement to service connection for a low back disability, to include as secondary to service-connected left knee disability, is remanded. The Board notes that the October 2019 VA examiner diagnosed the Veteran with degenerative arthritis of the spine. See October 2019 C&P Exam. A review of the service treatment records shows that the Veteran had normal spine with no complaint of recurrent back pain in the March 1983 enlistment examination, February 1987 examination, and October 1987 separation examination. See June 2015 STR Medical. Despite the lack of any medical complaints, treatment, or diagnosis, in the August 2017 hearing, he attested that he injured his low back on Halloween night in 1984 playing football. He claimed that he had low back pain but did not seek treatment until about 2001. In the alternative, he also alleged that his low back disability manifested as a result of his service-connected left knee disability. He claimed that Dr. Deaton and Dr. Merritt stated that his left knee disability caused his back disability. In the November 2016 VA medical opinion, the examiner opined that the Veteran's low back disability is less likely than not proximately due to or the result of the Veteran's service-connected left knee disability. Additionally, the examiner opined that his low back disability, which clearly and unmistakably existed prior to service, was not aggravated beyond its natural progression by an in-service event, injury, or illness. The examiner explained that the contention that one joint of the body having pain causes a person to favor or 'unload' on another joint and therefore causes arthritis on the other is often cited but it is biomechanically incorrect and has been disproven in the orthopedic and occupational medicine literature. Arthritis formation would require increase speed and increase sheer forces across the joint, a situation only seen in the paralytic or waddling gait abnormality. The Veteran does not have this. The conditions are comorbid, separate, and independent of each other. They may be present alone or together. There is no nexus or link between them. In the January 2019 VA examination, the examiner diagnosed the Veteran with degenerative arthritis of the spine and opined that the Veteran's low back disability is at least as likely as not incurred in or caused by the claimed in-service injury, event, or illness. The examiner explained that the Veteran had no issues related to his low back prior to military service and that the Veteran's low back disability manifested during service as documented in the service medical records. As there is evidence of current, chronic, and continuous treatment and care a nexus is established. The examiner also opined that the Veteran's low back disability is at least as likely as not proximately due to or the result of the Veteran's service-connected left knee disability. The examiner opined that the current severity of the service-connected left knee disability warrants by proximity, association of the claimed secondary low back disability. The low back disability began subsequent to the service-connected left knee disability and is the direct result of the antecedent condition. The medical literature supports this causation and as such a nexus is established. Then, in the October 2019 VA examination, the examiner diagnosed the Veteran with degenerative arthritis of the spine and opined that his low back disability is less likely than not proximately due to or the result of the Veteran's service-connected left knee disability. The examiner explained that although the Veteran injured his left knee playing basketball in service in 1984 there was no objective documentation that he was walking with a limp or any type of chronic antalgic/abnormal gait during the 1980s, 1990s, or 2000s. There are studies that show that a chronic injury to one lower extremity joint can negatively affect other lower extremity joints and even the spine, but only if it alters proper body mechanics resulting in a chronically abnormal gait or limp, which puts additional strain on the other lower extremity joints causing injury. Without any objective evidence that the Veteran had a chronic limp at the time, there is no basis to believe that his left knee disability affected his lower back condition. Moreover, the records show that he complained of low back pain in 1995 when he was involved in a work-related motor vehicle accident. He reinjured his back when he was lifting heavy equipment for Pepsi and again when lifting a sofa while working at a furniture store. The examiner determined that there is no clear, objective link between his left knee condition causing his lower back condition and as such a nexus has not been established. The Board notes that despite the Veteran's testimony, no medical opinions were submitted authored by Dr. Deaton or Dr. Merritt stating that his left knee disability caused his back disability. Moreover, treatment records from Dr. Deaton and Dr. Merritt do not show any support that Dr. Deaton and Dr. Merritt attributed the Veteran's low back disability to his left knee disability. The Board finds that a remand is warranted for various reasons. First, in the October 2019 medical opinion, the examiner stated that there is "no clear, objective link" between his left knee disability causing his low back disability. A finding of clear and objective link is a higher standard than less likely than not and as such, it is unclear whether the examiner held a higher standard when rendering her opinion. Second, the October 2019 VA examiner did not opine as to whether the Veteran's left knee disability is aggravated by his low back disability. Third, the October 2019 examiner explained that the only way for one lower extremity joint to affect the other lower extremity joint and even the spine is if it alters proper body mechanics resulting in a chronically abnormal gait or limp. The treatment records do not indicate an abnormal gait, but they do show that he ambulates with an assistance of a cane. See March 2020 CAPRI. Further, in the October 2019 VA examination, the examiner noted that the Veteran has guarding resulting in abnormal gait or abnormal spinal contour. As the examiner determined that the Veteran has abnormal gait and stated that the only way for one lower extremity joint to affect the other lower extremity joint is if it results in chronic abnormal gait, the examiner's findings and medical opinion is inconsistent. Based on the foregoing, the Board finds that a remand is warranted. 5. Entitlement to service connection for a right knee disability, to include as secondary to service-connected left knee disability, is remanded. The Board notes that in the January 2019 Disability Benefits Questionnaire (DBQ) the Veteran was diagnosed with a right knee strain, meniscal tear of the right knee, and degenerative arthritis of the right knee. See February 2019 C&P Exam. A review of the STRs shows that the Veteran had normal lower extremities with no complaint of locked knee or knee pain in the March 1983 enlistment examination, February 1987 examination, and October 1987 separation examination. See June 2015 STR Medical. The Board notes that in a September 1984 STR he injured his left knee while playing basketball. However, there are no note of a right knee injury. Despite the lack of any medical complaints, treatment, or diagnosis, he attested that he injured his right knee in a basketball game in service. In the alternative, he also claimed that in 2004 he slipped and fell due to his service-connected left knee disability and subsequently injured his right knee. Additionally, he claimed that due to his service-connected left knee disability he favored the right knee and placed most of his weight on his right knee. See August 2017 Hearing Transcript. A review of the post-service medical records shows that he was afforded VA examinations in June 2011, March 2016, and June 2020. In the June 2011 VA examination, the examiner diagnosed the Veteran with a right knee strain and opined that his right knee strain is at least as likely as not related to the left knee. The examiner explained that this was a result of a progression of the left knee disability and change in gait station that cause extra wear on the right knee. In the March 2016 VA examination, the examiner assessed his bilateral knee disability but did not render an opinion as to the etiology of the Veteran's right knee disability. In the November 2016 VA addendum opinion, the examiner opined that the Veteran's right knee disability is less likely than not proximity due to or the result of his service-connected left knee disability. The examiner also opined that the Veteran's right knee disability, which clearly and unmistakably existed prior to service, was not aggravated beyond its natural progression by an in-service event, injury, or illness. The examiner explained that the contention that one joint of the body having pain causes a person to favor or 'unload' on another joint and therefore cause arthritis on the other is often cited. However, this is biomechanically incorrect and has been disproven in the orthopedic and occupational medicine literature. Arthritis formation would require increase speed and increase sheer forces across the joint, a situation only seen in the paralytic or waddling gait abnormality. He does not have this. The conditions are comorbid, separate, and independent of each other. They may be present alone or together. There is no nexus or link between them. In the January 2019 DBQ, the examiner diagnosed the Veteran with right knee strain, right knee meniscal tear, and arthritis of the right knee and opined that the Veteran's right knee disability is less likely than not proximately due to or the result of his service-connected left knee disability. The examiner explained that his right knee disability began subsequent to the service-connected left knee disability and is the direct result of an antecedent condition. The medical literature supports this and as such a nexus is established. In the June 2020 VA examination, the examiner opined that the Veteran's right knee disability is less likely than not incurred in or caused by the claimed in-service injury, event, or illness. The examiner also opined that it is less likely than not proximately due to or the result of the Veteran's service-connected left knee disability. The examiner explained that there is no evidence of a right knee condition while in service, to include in the separation examination. There is no evidence of a right knee condition until January 2004 when he twisted his knee at work. Therefore, it is less likely than not that his current right knee disability is due to events in service. His degenerative joint disease of the right knee is more likely than not due to normal wear and tear and age as age is the single greatest predictor of osteoarthritis, even in the absence of chronic conditions or acute injury. Additionally, as the 2004 fall was a more likely source of his current right knee disability and is not caused by condition of the contralateral joint (accepted medical knowledge and practice, supported by standard texts such as Wheeless) it is less likely than not that his injuries are in no way related or due to his left knee disability. There is no evidence to support a finding that his fall was due to his left knee. The Board finds that a remand is warranted for various reasons. First, there is no medical opinion on aggravation (i.e., worsening). Second, the October 2019 examiner explained that the only way for one lower extremity joint to affect the other lower extremity joint is if it alters proper body mechanics resulting in a chronically abnormal gait or limp. The treatment records do not indicate an abnormal gait, but it does show that he ambulates with an assistance of a cane. See March 2020 CAPRI. Further, in the October 2019 VA examination, the examiner noted that the Veteran has guarding resulting in abnormal gait or abnormal spinal contour. As the examiner determined that the Veteran has abnormal gait and stated that the only way for one lower extremity joint to affect the other lower extremity joint is if it results in chronic abnormal gait, the examiner's findings and medical opinion is inconsistent. Based on the foregoing, the Board finds that a remand is warranted. 6. Entitlement to a TDIU is remanded. The Board will defer adjudication of this matter as two service connection claims are remanded. The matters are REMANDED for the following action: 1. Obtain any outstanding VA or identified private treatment records. Additionally, obtain the 2002 (possibly 1999) MRI scan of the low back. In the July 2002 VA treatment record, it was noted that the Veteran injured his back about three years ago and had an MRI scan of his low back that showed a torn disc. See July 2004 Medical Treatment Record Government Facility. 2. Thereafter, obtain an addendum opinion from an appropriately qualified examiner to determine the nature and etiology of any low back disability and right knee disability. The claims file, including a copy of this remand, must be made available to be reviewed by the examiner. A record of the review of the claims file should be documented in the examination report. All indicated diagnostic tests should also be completed. Low back disability - The examiner must identify/diagnose any disability of the low back that presently exists or that has existed during the appeal period (since 2011). For each identified disability, state whether it is at least as likely as not (a fifty percent probability or greater) that the Veteran's low back disability was (a) caused by or (b) has been aggravated (worsened beyond the natural progress of the disorder) by his service-connected left knee disability. Right knee disability - The examiner must identify/diagnose any disability of the right knee that presently exists or that has existed during the appeal period (since 2011). For each identified disability, state whether it is at least as likely as not (a fifty percent probability or greater) that the Veteran's right knee disability was (a) caused by or (b) has been aggravated (worsened beyond the natural progress of the disorder) by his service-connected left knee disability. The examiner is reminded that the standard does not require that worsening be permanent worsening. The examiner is asked to consider the following: The Board notes that the October 2019 examiner explained that the only way for one lower extremity joint to affect the other lower extremity joint and even the spine is if it alters proper body mechanics resulting in a chronically abnormal gait or limp. The treatment records do not indicate an abnormal gait, but they do show that he ambulates with an assistance of a cane. See March 2020 CAPRI. Additionally, in the October 2019 VA examination, the examiner noted that the Veteran has guarding resulting in abnormal gait or abnormal spinal contour. As the examiner determined that the Veteran has abnormal gait and stated that the only way for one lower extremity joint to affect the other lower extremity joint is if it results in chronic abnormal gait, the examiner's findings and medical opinion appears to be inconsistent. Please provide further clarification as it would be beneficial to the Board. A detailed rationale for the opinion must be provided. If the examiner is unable to offer the requested opinion, it is essential that the examiner offer a rationale for the conclusion that an opinion could not be provided without resort to speculation, together with a statement as to whether there is additional evidence that could enable an opinion to be provided, or whether the inability to provide the opinion is based on the limits of medical knowledge. 3. Thereafter, readjudicate the claims on appeal, to include the claim for TDIU. S. HENEKS Veterans Law Judge Board of Veterans' Appeals Attorney for the Board P. Noh, Counsel 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.