DETERMINATION OF APPEAL PANEL	
	
CITATION:	Drekovic v Drek-A-Dek Roofing Contractors [2022] NSWPICMP 326	
		
APPELLANT:	Michael Drekovic	
		
RESPONDENT:	Drek-A-Dek Roofing Contractors	
		
Appeal Panel:	Member Catherine McDonald
Medical Assessor Roger Pillemer 
Medical Assessor Brian Stepheson	
		
DATE OF DECISION:	16 August 2022	
		
CATCHWORDS: 	wORKERS cOMPENSATION - Total knee replacement; extent of section 323 of the Workplace Injury Management and Workers Compensation Act 1998 deduction; previous non-work-related injuries and treatment; asymptomatic at time of injury; osteoarthritis shown on scans at time of work injury; Cole v Wenaline and Vitaz v Westform considered; Held — one half deduction was open to Medical Assessor; Medical Assessment Certificate confirmed. 

BACKGROUND TO THE APPLICATION TO APPEAL
1.	On 8 June 2022 Michael Drekovic lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Dr Rob Kuru, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on 11 May 2022.
2.	The appellant relies on the grounds of appeal in s 327(3)(d) of the Workplace Injury Management and Workers Compensation Act 1998 (1998 Act) – that the MAC contains a demonstrable error.
3.	The delegate was satisfied that, on the face of the application, at least one ground of appeal has been made out. We conducted a review of the original medical assessment, limited to the ground of appeal relied on. 
4.	The WorkCover Medical Dispute Assessment Guidelines 2018 set out the practice and procedure in relation to the medical appeal process under s 328 of the 1998 Act. An Appeal Panel determines its own procedures in accordance with the WorkCover Medical Assessment Guidelines 2018.
5.	The assessment of permanent impairment is conducted in accordance with the NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment, 4th ed reissued 1 March 2021 (the Guidelines) and the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th ed (AMA 5). 
RELEVANT FACTUAL BACKGROUND
6.	Mr Drekovic was employed by his own company, Sebright Pty Limited t/as Drek-A-Deck Roofing Contractors (Drek-A-Deck) as a roofer. He said in his statement that an injury to his right knee caused him to undergo an open total medial meniscectomy in 1977 from which he completely recovered. The history provided to the Medical Assessor and to Dr Patrick was that the 1977 injury and surgery was to his left knee. In 1978 Mr Drekovic injured his right knee playing basketball. He again underwent surgery from which he totally recovered.
7.	On 9 April 2003 he twisted his left knee while descending a ladder. He was referred to Dr Woods and underwent two arthroscopies before undergoing a high tibial osteotomy in 2006. Those operations were unsuccessful in alleviating the instability of his left knee. In 2011 he began to experience symptoms in his right knee and he suffered an injury to it in 2013 after his left knee collapsed. 
8.	On 2 October 2013 Mr Drekovic underwent a left total knee replacement. In 2015 Mr Drekovic suffered an injury to his left wrist while undergoing a functional assessment at the request of Drek-A-Deck’s insurer.
9.	On 8 March 2016 the Workers Compensation Commission determined he had suffered a consequential condition in his right knee as a result of his left knee injury and ordered Drek-A-Deck to pay his s 60 expenses of and incidental to a right total knee replacement.
10.	Mr Drekovic brought proceedings in 2021 seeking permanent impairment compensation in respect of his left knee. The Personal Injury Commission (the Commission) issued consent orders clarifying that the claim for compensation was in respect of both of both of his lower extremities and his left upper extremity in respect of the injury to his wrist.
11.	The Medical Assessor assessed Mr Drekovic on 1 April 2022. He assessed 15% whole person impairment (WPI) in respect of each of Mr Drekovic’s lower extremities on the basis that he had a good result from two knee replacements. He deducted 8% from each assessment under s 323 of the 1998 Act for pre-existing osteoarthritis. He assessed 4% WPI in respect of the left wrist and 1% for scarring under the Table for the Evaluation of Minor Skin Impairments (TEMSKI).
PRELIMINARY REVIEW
12.	We conducted a preliminary review of the original medical assessment in the absence of the parties and in accordance with the WorkCover Medical Assessment Guidelines 2018.
13.	As a result of that preliminary review, we determined that it was not necessary for the worker to undergo a further medical examination. Subject to the provision to the radiological reports, we considered that there was sufficient information in the file to determine the appeal. A direction was made that Mr Drekovic provide copies of those reports and we have received them.
14.	We noted at the review conference that the file contained the cover page of a decision given by Member McDonald in respect of Mr Drekovic’s right knee. The following direction was made and issued by the Commission on 29 July 2022:
“The parties are to inform the Commission within seven days if there is any objection to Member McDonald remaining a member of the Appeal Panel, noting the Certificate of Determination dated 8 March 2016 (which appears to be incomplete) in respect of the consequential condition in Mr Drekovic’s right knee. 
Please note that Member McDonald has no recollection of a decision given over six years ago and does not retain a copy of any decision. There is no copy of the decision on the Commission’s website. Unless there is an objection by either party, the Panel does not consider that there is any reason for the Member to recuse herself.” 
15.	The Commission did not receive any request that Member McDonald recuse herself.
EVIDENCE
16.	The Appeal Panel has before it all the documents that were sent to the Medical Assessor for the original medical assessment and has taken them into account in making this determination.  
17.	The parts of the medical certificate given by the Medical Assessor that are relevant to the appeal are set out, where relevant, in the body of this decision. 
18.	The radiological reports provided in response to our direction are summarised below.
SUBMISSIONS 
19.	Both parties made written submissions. They are not repeated in full, but we have considered them. 
20.	In summary and in submissions prepared by his solicitor, Mr Chadwick, Mr Drekovic submitted that the Medical Assessor made a demonstrable error in making deductions of 50% under s 323, failing to apply both that section and the Guidelines. He submitted that the Medical Assessor was required to determine the degree of permanent impairment suffered as a result of the 2003 injury and whether a proportion was due to injuries in his knees in the 1970s and the surgery performed as a result of those injuries. He said that the Medical Assessor did not identify the available evidence which permitted him to apply a deduction of more than one-tenth for the previous meniscectomies other than a paper published 40 years after that surgery. Mr Drekovic said that the available evidence showed that he had made a good recovery from the surgery in the 1970s and that his knees were not symptomatic at the date of injury in 2003. At most, a deduction of one-tenth (1.5%, rounded to 2%) was appropriate to reflect the difficulty in determining the extent to which osteoarthritis contributed to the assessments.
21.	In reply, Drek-A-Deck referred to Cole v Wenaline Pty Ltd (Cole) and Marks v Secretary, Department of Communities and Justice (Marks) and said that the test was not whether a pre-existing injury or condition was symptomatic before a work injury but whether the condition contributed to the overall level of impairment, noting that in Simpson AJ said in Marks:
“That would deny the relevance of any contribution that might be made by a pre-existing, but dormant, condition that, for example, rendered the claimant more vulnerable to the injury that precipitated the impairment under assessment.” 
22.	Drek-A-Deck submitted that the Medical Assessor gave sufficient reasons to explain why a deduction of one-tenth of the assessed impairment is inconsistent with the available evidence. 
FINDINGS AND REASONS 
23.	The procedures on appeal are contained in s 328 of the 1998 Act. The appeal is to be by way of review of the original medical assessment but the review is limited to the grounds of appeal on which the appeal is made. 
24.	In Campbelltown City Council v Vegan the Court of Appeal held that the Appeal Panel is obliged to give reasons. Where there are disputes of fact it may be necessary to refer to evidence or other material on which findings are based, but the extent to which this is necessary will vary from case to case. Where more than one conclusion is open, it will be necessary to explain why one conclusion is preferred. On the other hand, the reasons need not be extensive or provide a detailed explanation of the criteria applied by the medical professionals in reaching a professional judgement.
The MAC
25.	It is not necessary to consider the Medical Assessor’s findings with respect to Mr Drekovic’s left wrist and scarring in detail.
26.	The Medical Assessor summarised the history of the onset of Mr Drekovic’s symptoms from 9 April 2003. He said:
“Mr Drekovic has had injuries to both knees, the left in 1977 resulting in meniscectomy; the right in 1978 also resulting in meniscectomy.”
27.	The Medical Assessor set out his findings on examination. He said he “was able to review no imaging modalities today.” He summarised Mr Drekovic’s injuries and diagnoses:
“Mr Drekovic has undergone previous medial meniscectomies for non-work related injuries. Following a comparative minor injury at work, he went on to have a left total knee replacement from which he has had a good result. He subsequently became symptomatic in his right knee which he attributes to be consequent to the pathology in his left knee and again ultimately has undergone a knee replacement here from which he has had a good result. He has had an unusual injury to his left wrist where he has aggravated an underlying degenerative condition in his wrist.”
28.	The Medical Assessor explained his calculations and said that, under AMA 5, the score equated to a good result in respect of both knees.
29.	He commented on other opinions in the file and said:
“With respect to the report by Dr Patrick dated 10/04/2019, he has assessed both knees as having a fair rather than good result from the knee replacement surgeries. He found a better range of motion in the left wrist and hence assessed a slightly lower impairment. I note a 1/5 reduction for impairment in both knees due to pre-existing medial compartment osteoarthritis subsequent to meniscectomy.
With respect to the report by Dr Marchant [sic Machart] dated 22/10/2019, I agree with the assessment of both knees as having had a good outcome from the knee arthroplasties. I note Dr Marchant has made a two thirds deduction for the left knee and a three quarters deduction for the right knee.”
30.	The Medical Assessor said he considered that Mr Drekovic suffered from osteoarthritis in his left and right knees and left wrist. He said:
“Left and right knees: Mr Drekovic has undergone medial meniscectomies in both knees in the late 1970s following sporting injuries. The development of medial compartment osteoarthritis in his knees is largely the consequence of this injury and the subsequent surgery that he has had at that stage and injuries sustained to his knees at work are a lesser contributing component. To make a deduction of only 1/10 and applying the provisions of s.323(2) is inconsistent with the available evidence. Studies assessing progression of medial compartment osteoarthritis following medial meniscectomy have demonstrated that nearly 75% of people will have developed medial compartment osteoarthritis 20-30 years following their meniscectomy (Osteoarthritis of the knee after meniscal resection: Long term radiographic evaluation of disease progression, osteoarthritis and cartilage, Paradowski et al, Volume 24, Issue 5, May 2016, pages 794-800). I assess a ½ deduction for either knee.
With respect to the left wrist, a deduction would be appropriate if restricted range of motion was detected due to pre-existing osteoarthritis. No assessment of impairment has been made for restricted range of motion. Impairment of the left upper extremity relates to persistent sensory changes in the distribution of the ulnar nerve which is not a pre-existing condition.”
31.	The article to which the Medical Assessor referred is more clearly identified as PT Paradowski et al, ‘Osteoarthritis of the knee after meniscal resection: long term radiographic evaluation of disease progression’ Osteoarthritis and Cartilage, Volume 24, Issue 5 May 2016.
Other medical reports
32.	There are no reports from the doctors who treated Mr Drekovic’s knees in the file. Mr Drekovic’s solicitors provided us with the following reports which were referred to in Dr Patrick’s report dated 18 March 2011:
“X-ray Left Knee Dr Warwick Lee 11.04.2003
MRI Left Knee Dr Raymond Kuan 13.05.2003
Ultrasound Left Knee Dr Raymond Lau 24.11.2005
Bone Scan Dr Phillip Monaghan 16.03.2006
MRI Left Knee Dr Alex Petersen 02.05.2006.”
33.	Mr Drekovic’s solicitors provided us with the following reports which were referred to in Dr Patrick’s report dated 17 December 2015:
“MRI Right Knee Dr Michael Houang 16.07.2013
X-Ray Left Knee Dr Tony Gray 24.07.2013
X-Ray Left Hip and Left Knee Dr Gavin Landow 19.08.2014.”
34.	Many of those reports also appear in his general practitioner’s notes. The first X-ray was taken within two days of the injury on 11 April 2003. Dr Lee observed:
“There is moderately advanced osteoarthritis with joint space narrowing and osteophyte formation at the medial and patellofemoral joint compartment. There is a small joint effusion. No radio-opaque intra articular loose body is detected.”

35.	The report of the MRI scan dated 13 May 2003 reads:
“Clinical Notes - Old medial meniscectomy, recent MCL injury,? ACL injury.
…
There is marked attenuation, irregularity and heterogenity of the entire medial meniscus in keeping with previous partial meniscectomy.
…
Severe degenerative changes are seen in the medial joint compartment with focal full thickness cartilage loss seen along the articular surface of the medial tibial plateau where there is mild adjacent subchondral bone oedema. Cartilage irregularity and fissuring is also seen along the articular surface of the medial femoral condyle. Early marginal osteophyte formation is seen in relation to all 3 joint compartments. Mild cartilage thinning and irregularity is seen throughout remainder of the joint. No other areas of abnormal bone marrow signal seen.
Comment - 1) Low to intermediate grade distal ACL partial thickness tear. Chronic MCL sprain.
2) Partial medial meniscectomy. Severe medial compartment degenerative change with areas of full thickness cartilage loss.”
36.	The reports of other scans are consistent with those taken in the immediate aftermath of the injury.
37.	Mr Drekovic’s solicitor qualified Dr Patrick who prepared a series of reports. The first one relevant to the knee injury is dated 18 March 2011. Dr Patrick recorded the history of previous surgery in the 1970s and that “basically both knees were good until April 2003.” He described the first X-ray in the following way:
“l have examined these plain X-rays which demonstrate mild narrowing at the medial compartment with some osteoarthritic change. There is some early medial, tibial and patellar osteophyte formation and some peaking of intercondylar ridge. There may be minimal joint effusion. No loose bodies.”
38.	Dr Patrick agreed that the MRI scan report showed severe medial compartment degenerative change.
39.	Dr Patrick said:
“This injury has occurred on a background of some partial or sub-total medial meniscectomy many years earlier, in about 1976. Such extensive meniscectomy can of course predispose to development of some degree of osteoarthritic change. Prior to the work injury of 9 April 2003 however the left knee had been virtually asymptomatic for many years and the knee was not interfering at all with his ability to carry out his quite physical work to full capacity.”
40.	Dr Patrick provided his first assessment of permanent impairment in that report. Even at that time, he considered that a substantial deduction under s 323 was warranted:
“I believe this left knee is appropriately assessed using diagnosis base [sic] estimates combined with arthritis. The assessment is based on him having undergone the high tibial osteotomy surgery with reasonably good result thus far, and also the demonstrable mild cruciate laxity as shown on clinical examination on this occasion, and as noted by Dr Woods at examination under anaesthetic at the time of his arthroscopy of 23 June 2003 subsequent to the work injury, and also with assessment for partial medial meniscectomy. To these three diagnosis based estimates can be combined the assessment of 8% WPI (modest assessment - consideration could be given to 10% WPI at Table I 7- 31 AMAS Guides) leading to 23% WPI relating to Mr Drekovic's left knee, I believe it would be reasonable to make a deduction of one half of the assessed impairment in respect of any pre-existing, constitutional/degenerative condition, notwithstanding that the knee has been asymptomatic for many years leading up to this work accident.”
41.	An MRI scan of Mr Drekovic’s right knee on 17 July 2013 was reported as showing in respect of the medial compartment:
“Meniscus shows a complex tear and it is fragmented with the peripheral fragment displaced into the capsular recess and extruded. The body and anterior horn are small suggesting there has probably been partial meniscectomy. Weight bearing cartilage in the entire medial half of surfaces show thinning, almost to the cortex with subcortical marrow oedema and large marginal osteophytes. Posterior MFC weight bearing surface also shows chondral denudation with subchondral marrow oedema also. MCL is a little thickened distally with some periosteal fluid at the distal insertion.”
42.	The findings in respect of the other compartments are consistent.
43.	Dr Patrick prepared a report dated 17 December 2015. He saw a report from Dr Stubbs dated 25 September 2014 which does not form part of the evidence in these proceedings. Dr Patrick noted that Mr Drekovic’s right knee had deteriorated and required replacement. He disagreed with Dr Stubbs’ opinion that surgery in 1978 was a total meniscectomy and said:
“…this is not in keeping with the radiologist's report on MRI right knee of 16 July 2013 where it describes the medial meniscus at the right knee at that stage showing a complex tear fragmented with peripheral fragment displaced and extruded into the capsular recess. The body and anterior horn were described as small suggesting partial or sub-total meniscectomy in the past. It is likely that the remote surgery has consisted of an open sub-total medial meniscectomy rather than total meniscectomy (either can lead to development of osteoarthritic change with the passage of years, more so the total).
With respect, I believe that Dr Stubbs' comment (fifth unnumbered paragraph under heading ‘Opinion’ page 4 of his report) where he states that ‘Mr Drekovic's right knee outcome was decided in 1978’ is at best an oversimplification.
Dr Stubbs states in the preceding paragraph that the findings (of his paper referred to in the preceding paragraph) would suggest that at 24 years 60% of patients with this combination of injuries (open total medial meniscectomy and associated anterior cruciate ligament injury) will have proceeded to osteoarthritis’. Thus, this infers that on balance of probability such individuals will have proceeded to osteoarthritic change after 24 years. This leaves 40% of individuals who may not have developed such osteoarthritic change.
…
At the very least, the need for such right total knee replacement surgery has been brought forward significantly in time (possibly by many years) such that he may well come to require revision total right knee replacement surgery during his lifetime.”
44.	In a further report dated 21 December 2017 Dr Patrick said that he had not been asked to assess WPI and noted that Mr Drekovic’s left wrist had not yet stabilised for assessment. In respect of each knee, Dr Patrick assessed a fair result and 20% WPI but allowed a deduction of two-fifths under s 323. He said:
“I believe the deductible proportion in respect of each knee is appropriately two fifths of the assessed impairment in respect of pre-existing constitutional, developmental or degenerative condition which is contributing to his impairment assessments now.”
45.	Dr Patrick maintained that deduction when he made an assessment of WPI in his report dated 10 April 2019, on which Mr Drekovic’s claim for permanent impairment compensation is based. It is noteworthy that Mr Drekovic’s claim for 27% WPI included a s 323 deduction of 40% in respect of a pre-existing condition in each knee. 
46.	Dr Machart said in his report dated 11 February 2020, prepared at the request of Drek-A-Deck’s insurer:
“There is evidence of pre-existing injury to both knees, subjected to cartilage operations. Meniscal and/or ligament injury is a predisposing factor to osteoarthritis. It is evident that osteoarthritis was already in existence at the time of injury on 9/4/2003.”

47.	Dr Machart assessed a good result in respect of each knee replacement and said:
“Left Knee Two-thirds deduction left knee for pre-existing osteoarthritis. Symptoms triggered by the injury, not substantial injury in the context of the pre-existing condition. Arthritis was always going to be evident because of loss of articular cartilage, and suggestion of ACL injury, the predominant causative factors as opposed to the injury. Undoubtedly the knee would have been symptomatic in absence of the injury. WPI as a result of injury is 15 minus two-thirds = 5% WPI.
Right Knee Injury in the context of previous meniscectomy, injury, and osteoarthritis evident at the time of injury, progressive condition that would have been evident irrespective of injury. Three-quarter deduction applicable. 15 minus three quarters = 3.75, rounded up to 4% WPI.”
Consideration
48.	Section 323 provides:
“323   Deduction for previous injury or pre-existing condition or abnormality
(1)	In assessing the degree of permanent impairment resulting from an injury, there is to be a deduction for any proportion of the impairment that is due to any previous injury (whether or not it is an injury for which compensation has been paid or is payable under Division 4 of Part 3 of the 1987 Act) or that is due to any pre-existing condition or abnormality.
(2)	If the extent of a deduction under this section (or a part of it) will be difficult or costly to determine (because, for example, of the absence of medical evidence), it is to be assumed (for the purpose of avoiding disputation) that the deduction (or the relevant part of it) is 10% of the impairment, unless this assumption is at odds with the available evidence.
Note—
So if the degree of permanent impairment is assessed as 30% and subsection (2) operates to require a 10% reduction in that impairment to be assumed, the degree of permanent impairment is reduced from 30% to 27% (a reduction of 10%).
(3)	The reference in subsection (2) to medical evidence is a reference to medical evidence accepted or preferred by the medical assessor in connection with the medical assessment of the matter.
(4)	The Workers Compensation Guidelines may make provision for or with respect to the determination of the deduction required by this section.
…”
49.	Mr Drekovic submitted that the task of the Medical Assessor was to determine the impairment resulting from the injury in 2003 and the proportion due to the injuries in the 1970s and the subsequent surgery and to determine the proportion. That statement misstates the test. In Cole (a case in which the worker had suffered two injuries), Schmidt J said:
“What s 323 required, however, was that the evidence be considered, so that it could be determined, firstly, what the level of impairment after the second injury was. Secondly, whether a proportion of that impairment was due to the first injury. Thirdly, what that proportion was. Undoubtedly in undertaking this exercise, the medical members of an Appeal Panel must utilise their medical judgement, knowledge and experience. Nevertheless, all stages of the statutory exercise must be undertaken in the light of the evidence and without the making of assumptions not provided for by the section.”
50.	The first task for the Medical Assessor was not to determine the impairment resulting from the 2003 injury but to make an assessment of Mr Drekovic’s permanent impairment as he presented on the day of the examination - that is an assessment after the injury. His second task was not merely to determine the proportion due to the injuries in the 1970s and the subsequent surgery. He was required to take account of any pre-existing condition and to assess the resulting impairment. 
51.	The fact that Mr Drekovic had made a good recovery from the surgery in the 1970s and was not symptomatic does not mean that osteoarthritis resulting from the surgery was not a contributing factor to the impairment. The Medical Assessor was required to review the evidence and use his clinical judgement in reaching his assessment. In Vitaz v Westform (NSW) Pty Ltd  Basten JA said:
“…The resulting principle is that if a pre-existing condition is a contributing factor causing permanent impairment, a deduction is required even though the pre-existing condition had been asymptomatic prior to the injury. In the absence of any medical evidence establishing a contest as to whether the pre-existing condition did contribute to the level of impairment, the complaint about a failure to give reasons must fail. An approved medical specialist is entitled to reach conclusions, no doubt partly on an intuitive basis, and no reasons are required in circumstances where the alternative conclusion is not presented by the evidence and is not shown to be necessarily available.”
52.	The Medical Assessor was required to exercise his clinical judgement in making the assessment and to give reasons for his assessment. Mr Drekovic submitted that that the Medical Assessor did not identify the evidence which permitted him to depart from a one-tenth deduction “for the previous meniscectomies” other than “a research paper” prepared 40 years after those operations. 
53.	The Medical Assessor said that he considered that Mr Drekovic suffered osteoarthritis in both knees before the injury in April 2003. He described studies which showed that development of osteoarthritis was more likely after a meniscectomy and gave an example. Osteoarthritis is generally the condition which gives rise to a need for total knee replacement. It is not relevant that the study to which the Medical Assessor referred took place 40 years after Mr Drekovic underwent surgery – it is the findings of the study which are relevant about the likelihood of the development of osteoarthritis after meniscal surgery. It was not the meniscectomies themselves that required the deduction but the condition of osteoarthritis to which those surgeries contributed. 
54.	While the Medical Assessor did not see the radiological reports, they are summarised in the reports prepared by Dr Patrick and Dr Machart and there was abundant evidence that he suffered significant osteoarthritis before the injury. It would have been preferable for the Medical Assessor to have located the references to the radiological reports in the file and to have specifically referred to them. However, we do not consider that would have changed the result 
55.	The X-ray undertaken within days of the left knee injury in 2003 shows that there was moderately advanced osteoarthritis. Those findings pre-date the injury, despite Mr Drekovic’s experience of being asymptomatic and being able to work a roofer. The MRI scan report dated 13 May 2003 (within five weeks of the injury) showed severe medial compartment degenerative change with areas of full thickness cartilage loss. This finding represents end stage osteoarthritis.
56.	In the experience of the medical members of the Panel, it is not uncommon to be faced with a patient who presents with bilateral varus knees (advanced medial compartment osteoarthritis) of equal severity even though they are only complaining of pain in one knee and not having any symptoms in the other. In that example, if weight-bearing views of the knees were carried out prior to any injury, bone-on-bone contact would result in an assessment 50% lower extremity impairment or 20% WPI. In other words, a person can have advanced osteoarthritis of a joint which is asymptomatic
57.	The opinion the Medical Assessor formed about the role of those previous surgeries and the development of osteoarthritis was consistent with that of both Dr Patrick and Dr Machart who differed only as to the extent of the s 323 deduction. Both accepted that the previous meniscectomies contributed to the osteoarthritis suffered by Mr Drekovic. In assessing that contribution, Dr Patrick made a deduction of two-fifths or 40% in respect of each knee from the impairment he assessed. Dr Machart proposed a more significant deduction and each of those assessments were open. The deduction of one half was a valid exercise of the Medical Assessor’s clinical judgment.
58.	For these reasons, the Appeal Panel has determined that the MAC issued on 11 May 2022 should be confirmed.