1. On 23 October 2024 Sophie Roy, the appellant, 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 9 October 2024.
2. The appellant relies on the following grounds of appeal under s 327(3) of the Workplace Injury Management and Workers Compensation Act 1998 (the 1998 Act):
   • the assessment was made on the basis of incorrect criteria, and
   • the MAC contains a demonstrable error.
3. The delegate is satisfied that, on the face of the application, at least one ground of appeal has been made out. The Appeal Panel has conducted a review of the original medical assessment but limited to the ground(s) of appeal on which the appeal is made.
4. Rule 128 of the Personal Injury Commission Rules 2021 (the PIC Rules) and Procedural Direction PIC7 - Appeals, reviews, reconsiderations and correction of obvious errors in medical disputes 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 r 128(1) of the PIC Rules.
5. The assessment of permanent impairment is conducted in accordance with the SIRA NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment, 4th ed

1 March 2021 (the Guides) and the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th ed (AMA 5). "WPI" is reference to whole person impairment. "Baseline WPI" is a reference to the total WPI assessed before deduction for the effect of pre-existing injury, condition or abnormality pursuant to s 323 of the 1998 Act.

1. On 13 August 2024 this matter was referred to the Medical Assessor for a WPI assessment of injuries to the left lower extremity (knee) right lower extremity (knee) and scarring - TEMSKI. All of these injuries occurred on a deemed date of 21 November 2019.
2. Ms Roy was employed as a security guard who suffered an onset of bilateral knee pain whilst working. In particular in 2019 she was obliged to patrol St Mary's Cathedral and she noticed progressively worsening pain in her left knee. She came to surgery on 8 April 2021 on the left knee.
3. The Medical Assessor noted that she was not having treatment for the right knee. The Medical Assessor noted that that Ms Roy was "intermittently taking paracetamol predominantly for her back pain rather than her knee pain".
4. The Medical Assessor found a baseline WPI of 20% for the injury to the left knee, from which he deducted ¾ pursuant to s 323 of the 1998 Act. He found a baseline WPI of 0%, from which, curiously, he also deducted three-quarters pursuant to s 323. He found a baseline WPI of 0% for the scarring assessment. These calculations yielded a Combined Table assessment of 5%.

1. The Appeal Panel conducted a preliminary review of the original medical assessment in the absence of the parties and in accordance with the Procedural Direction PIC7.
2. Ms Roy requested that she be re-examined by a member of the Panel. For the reasons given below such an examination was required due to the errors made within the MAC.

1. 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.

1. 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.

1. Both parties made written submissions which have been considered by the Appeal Panel.

1. 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.
2. In Campbelltown City Council v Vegan [2006] NSWCA 284 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.

1. In taking the history at [4] of the MAC the Medical Assessor did not mention the injury to the right knee, beyond an opening comment:

"Ms. Roy told me that she believes she has developed osteoarthritis in her knees due to the nature and condition of her being a security guard".

1. So far as the back injury was concerned in the history the Medical Assessor noted in the same paragraph:

"....She is intermittently taking paracetamol predominantly for back pain."

"She says she does not trust the right knee. She has pain in the front of her knee".

1. In his summary at [5], the Medical Assessor said:[1]

"Range of motion in both knees is from 0°-130°. Both knees are coronally and sagittally stable.

Her gastrocnemius circumference is 39cm and symmetrical. The lower limbs are neurovascularly intact."

1. In his summary at [7], the Medical Assessor said:

"Ms Roy aggravated pre-existing osteoarthritis of the left knee without a specific injury. She has progressively started developing symptoms in her right knee."

1. Is any proportion of loss of efficient use or impairment or whole person impairment, due to a previous injury, pre-existing condition or abnormality? Yes.

d) If so, please indicate which body part/system is affected by the previous injury, pre-existing condition or abnormality.

Left lower extremity (knee) and right lower extremity (knee).

"Imaging is not supplied to make an assessment of the right knee on the basis of osteoarthritis. Impairment is not assessable on the basis of range of movement or diagnosis basis estimate.

Scarring TEMSKI: This is assessed according to SIRA, page 74, Table 14.1. On the basis of the surgical wound being consistent with the surgery undertaken, a good colour match and barely distinguishable without trophic change, 0% whole person impairment is assessed for Scarring TEMSKI"

1. Paragraph [10c] provides an opportunity for the Medical Assessor to give some brief comments about the evidence before him. In considering the report of Dr Patrick of 28 November 2022 the Medical Assessor said:[2]

"With respect to the report by Dr Patrick dated 28/11/2022, Dr Patrick indicates that he is of the belief that the nature and conditions of Ms Roy's employment and the 3 shifts she is working at St Mary's Cathedral 'particularly ascending and descending overly long staircases' has 'brought her undone'. He says 'This is particularly 'on the background of a similar type of work ever since 2009 or 2010 when she started with Sydney Night Patrol' [as written]. It should be noted that standing and walking in the non-injured knee has not been found to be a risk factor for the development of osteoarthritis. Accepted risk factors are age, overweight/obesity, history of previous trauma particularly meniscectomy or meniscus injury, family history and female sex. It is generally regarded that exercise and activity in the absence of a knee injury are protective.

I have not assessed impairment for the right knee as I did not find evidence of collateral ligament laxity at assessment today."

1. At the same point in his MAC, the Medical Assessor referred to the report of Dr Frank Machart of 14 March 2023 saying:

".......I am in agreement but in the absence of x-rays, impairment is not assessable for the right knee. I note Dr Marchant (sic Machart) has made a 100% deduction for the left knee".

1. In considering the deduction pursuant to s 323 of the 1998 Act, at [11] the Medical Assessor stated that osteoarthritis in both knees was relevant. He said:

"...(i) In the absence of the pre-existing condition, there would have been no assessable impairment.

e) Whilst the extent of the deduction is difficult or costly to determine the available evidence is that the deductible proportion is large and a deduction of one tenth is at odds with the available evidence. In my opinion the deductible proportion is three quarters for the following reasons:

(i) Ms Roy has bilateral constitutional degenerative arthritis of both of her knees. In the absence of pre-existing degenerative arthritis in both knees likely the consequence of age, weight and sex, the nature and conditions of Ms Roy's employment not have been associated with the development of symptoms from the osteoarthritis and consequently impairment."

1. Ms Roy submitted firstly that the matter had been referred on the basis that the appellant had disease injuries or aggravation injuries to both knees. Ms Roy then submitted that the Medical Assessor had fallen into error by misunderstanding the nature of the referral.
2. Unfortunately, that submission was misconceived, as the referral was in clear terms. The Medical Assessor was asked to assess the right knee as a consequential condition, as we explain below.
3. For completeness, however, we set out Ms Roy's submissions.
4. We were referred to the comments we have reproduced at [10c] of the MAC and Ms Roy made the following submissions:
   • there was no basis for the Medical Assessor's apparent assumption that the right knee injury had been referred as a consequential condition. In making that assumption he had misdirected himself and fallen into error;
   • in the alternative, the Medical Assessor had failed to provide his reasoning process if indeed he had assessed the claim on the basis that the right knee condition was consequential;
   • with regard to both knees, the Medical Assessor had assumed that he was dealing with a s 4 (b)(ii) case rather than an s 4(b)(i) case. The error was alleged to have been that the Medical Assessor assumed that he was dealing with an injury defined by the aggravation etc,[3] of a disease rather than one which had been contracted by Ms Roy because of her employment;
   • we were referred to State Government Insurance Commission v Oakley[4] in support of Ms Roy's submission that an injury's causation was "different depending on which mechanism of injury is found", and
   • without making express findings about causation, the Medical Assessor could not discharge his obligation, Ms Roy argued. His assumptions amounted to "bare ipse dixits".
5. Ms Roy then submitted again that by considering that the referral for the right knee was based on a consequential condition involving an aggravation of osteoarthritis, the Medical Assessor had erred because he assumed wrongly that he was not permitted to assess right knee on the basis of range of motion or diagnosis-based estimates, but rather needed collateral ligament laxity and X-rays.
6. The Medical Assessor did not explain why that was so and accordingly, it was submitted, fell into error. There was, it was submitted no reason why the Medical Assessor could not have assessed the impairment based on range of movement or diagnosis-based estimate.

1. Ms Roy submitted that the Medical Assessor had failed to apply the relevant Guides with regard to his assessment of her 16cm incision on her left knee with "well healed stab incisions" on the right. The Medical Assessor's error, it was submitted, was that he did not consider the effect of the scarring on Ms Roy, and thus failed to measure the objective clinical signs against the subjective effect of the scarring.
2. Alternatively, if he did take into account the subjective effect on the appellant, he had failed, as we understood the submission, to explain his reasoning process.

1. Ms Roy then addressed the Medical Assessor's findings as the deduction he made (75%) pursuant to s 323 of the 1998 Act.
2. Ms Roy assumed that the Appeal Panel was aware of relevant case law on how this task was to be approached. She referred to Cole v Wenaline Pty Ltd[5] and Southwell v Qantas Airways Pty Ltd.[6] _"_Much of this" Ms Roy submitted was the result of the Medical Assessor's erroneous assumptions, both as to the nature of the injuries referred and the assumption that the injury constituted the aggravation of underlying osteoarthritis.
3. Ms Roy submitted that "if the osteoarthritis was materially caused by employment (noting it was a 10 year period)" no deduction would have been made. We were referred to Bunnings Group Limited v Kearns.[7]
4. Ms Roy submitted that even if there were an underlying condition, the Medical Assessor was required to identify it and then identify the level of impairment that flowed from it at the time of the injury. The Medical Assessor did not do so, it was submitted. Alternatively, as we understood the submission, if he had done so, he did not explain his reasons.
5. The Medical Assessor was required, had there been an underlying condition, to evaluate its proportion, which had been symptomatic at the time of the onset of the work related injury, to assess the level that he had to attribute to, as opposed to the work injury, Ms Roy said.
6. The Medical Assessor had erred because he did not find that the appellant had such a pre-existing condition to either knee, as he merely assumed such, without applying causation principles. "He did not, and could not, therefore have properly engaged in s 323 Ms Roy submitted, again referring to Southwell."
7. Ms Roy submitted that she did not concede that she had any pre-existing condition, but that if such a condition were present it would have been too costly or difficult to determine and therefore a 10% deduction ought to have been made.
8. Finally, Ms Roy submitted that the Medical Assessor failed to provide adequate reasons in regard to:
   • his assumptions;
   • his diagnosis;
   • the question of causation;
   • impairment, and
   • s 323 full.
9. Ms Roy admitted that, "at the very least" his failure to provide a clear pathway of reasoning regarding s 4(b) demonstrated flaws in his reasoning.
10. Ms Roy concluded her submissions by stating that the submissions she had made should not be taken as being the limit of the flawed reasoning. The Medical Assessor, it was claimed, had failed to explain each of the relevant crucial findings that he made in relation to the above substantive grounds. [What a very clumsy way of dealing with quite obvious case.]

Sydney Night Patrol and Inquiry Co Pty Ltd (respondent)

1. The respondent firstly referred to one of the earlier cases after the establishment of the Workers Compensation Commission, Phillip John Carmody v Walter Merriman, and Sons Pty Ltd.[8] It submitted that the appellant bore the onus of establishing that there had been a demonstrable error or the application of incorrect criteria.
2. The respondent noted that there was no dispute about matters of fact and history and that in fact Ms Roy had failed to demonstrate any demonstrable errors or any application of incorrect criteria.
3. Firstly we were referred to the description of Ms Roy's injury as claimed in the Application to Resolve a Dispute (ARD) form.
4. We were also referred to the Certificate of Determination by Member McAdam of 7 August 2024 which amended the claim as pleaded in the ARD.
5. The respondent submitted that the result of the amendment was that the matter was referred to the Medical Assessor as either a s 4 (b)(i) or s 4 (b)(ii) case.
6. The respondent submitted that the Medical Assessor did provide a WPI assessment for the right knee, albeit a 0% assessment. The Medical Assessor's comments at [10] and [11] of the MAC it was submitted, necessarily demonstrated that he accepted that there was a right knee condition in some form.
7. The respondent rejected the suggestion by Ms Roy that her right knee had been assessed as a consequential condition. It referred to the comments we have reproduced above at [10C] of the MAC regarding Dr Patrick's opinion. It submitted that the Medical Assessor had not dealt with the right knee injury on the basis of a consequential condition, save for the words "non-injured" (emphasis added) in that passage. The balance of the MAC, it was submitted, showed that the Medical Assessor had treated the right knee condition as a disease injury.
8. [This is loony tunes stuff. At 4 there was no mention of the right knee and it was only at page 4 in the summary that that inference might be available.]
9. On a "wholistic" [sic holistic] view of the MAC, it was submitted that the Medical Assessor's comments at [10C] of the MAC did not support the submission that he had treated the right knee condition as consequential. If the words "non-injured" (emphasis added) were removed, there would be little practical consequence on his views overall as to the nature of the right knee condition, it was submitted.
10. The respondent said that there was no basis for Ms Roy's submission that the Medical Assessor had assumed that he was dealing with an aggravation case when he should have been dealing with a case where the disease had been contracted in the course of employment.
11. The respondent referred to the terms of the referral and noted that there was no information therein as to causation. The respondent assumed that the Medical Assessor would have reviewed the ARD including the pleaded description, the Certificate of Determination and the documentation before him. These would have informed the nature of the injury he was to assess.
12. The pleadings and the amendment with the Certificate of Determination showed that Ms Roy claimed that she sustained bilateral knee injuries by way of a disease process as a result of her employment duties since 2010 - a claim that was consistent with either a s 4(b)(i) injury, and/or a s 4(b)(ii) injury.
13. The width of the pleadings that were submitted left it open for the Medical Assessor to favour one pleading over the other. This was a necessary step for him to take in order to fulfil his task.
14. It was submitted that the Medical Assessor explained why he did not agree with Dr Patrick's assessment and further that the Medical Assessor's opinion was reflected in the opinion of Dr Machart, whose opinion the respondent reproduced.
15. The respondent submitted therefore that "save for the opinion of Dr Patrick" there was no evidence before the Medical Assessor to allow him to favour the s 4 (b)(i) interpretation of the referral.
16. The MAC confirmed, it was submitted, that there had been an impact on both knees due to the nature and conditions of her employment and that therefore there had been an adequate path of reasoning shown.
17. We were referred to the well-known dicta of the High Court in Wingfoot Australia Partners Pty Ltd v Kocak.[9] The respondent concluded this section of its submissions by saying no error had been demonstrated by the Medical Assessor in his favouring the s 4(b)(ii) interpretation of the referral.
18. Insofar as the appellant had submitted that error had been shown in the methodology adopted by the Medical Assessor, the respondent submitted in relation to the right leg, that the submissions by Ms Roy were contradicted by the Medical Assessor himself, who had stated that there was no imaging supplied to make an assessment on the right knee, and further that there was no evidence of collateral ligament laxity on examination. The Medical Assessor agreed with Dr Machart that in the absence of X-rays, impairment was not assessable for the right knee.
19. We were referred to Chapter 3.26 of the Guides and Table 17-33 of AMA 5 to demonstrate that collateral ligament laxity was a diagnosis-based method of assessment.
20. The respondent noted that the Medical Assessor had found no evidence thereof.
21. As to the appellant's submissions about an alleged failure by the Medical Assessor to assess range of motion, we were referred to the Medical Assessor's findings on physical examination, which we have reproduced above.
22. The respondent submitted that if those measurements were correlated with Table 17-10 of AMA 5 it could be seen that there was no rateable impairment.
23. As to the assessment of osteoarthritis, the respondent referred to the Medical Assessor's agreement with Dr Machart that impairment was not assessable for the right knee in the absence of X-rays. We were referred to Dr Machart's comments in that regard.
24. We were referred to Chapter 3.20 of the Guides, which describe the methodology for assessing osteoarthritis, defined as cartilage loss. The respondent also referred to Table 17-31 of AMA 5, submitting that impairment was to be measured by consultation with imaging.
25. These guidelines, it was submitted, highlighted the need for scans when assessing an impairment caused by osteoarthritis, and there was no such imaging, save for a 2016 scan of the right knee. There was otherwise a lack of radiological evidence available and certainly none as to the state of Ms Roy's right knee after she went off work in late 2019. Thus, it was submitted, the Medical Assessor was unable to utilise that method to assess impairment.
26. It was further submitted that the reference by the Medical Assessor to a need for an X-ray was related to the method of assessing osteoarthritis and could not be conflated with the requirements for assessment with a diagnosis-based estimate or a range of motion method.
27. The assessment by the Medical Assessor was in accordance with the relevant guidelines and consistent with the appellant's presentation, it was submitted.
28. So far as the submission regarding the application of the TEMSKI scale was concerned, we were referred to the relevant Guides.
29. The respondent submitted that both the Medical Assessor and Dr Machart considered the scarring to be a standard surgical scar. There was, it was submitted, no indication in the MAC that Ms Roy reported any concerns to the medical assessor of a subjective nature.
30. The respondent then considered Ms Roy's submissions regarding the s 323 deduction. Again it was submitted that a holistic appreciation of the MAC showed that the employment duties of standing and walking would not themselves be sufficient to give rise to osteoarthritic symptoms.
31. There was a previous record of injury in 2016, when Ms Roy injured her right knee when playing with her grandchildren, but it was not until after her duties at St Mary's Cathedral and a twisting incident at Bunnings that she first reported left knee pain.
32. We were referred to the Medical Assessor's list of risk factors for the development of osteoarthritis and it was submitted that the Medical Assessor had identified a pre-existing condition, which he had explained at [11] of the MAC.
33. We were referred to Sawaneh v Flintwood Disability Services Limited.[10]

1. A Medical Assessor has the same functions of a Medical Appeal Panel,[11] which were described in Wingfoot Australia Pty Ltd v Kocak,[12] where the High Court (French CJ, Crennan, Bell, Gageler and Keane JJ agreeing) held from [47]:

"...The function of a Medical Panel is neither arbitral nor adjudicative: it is neither to choose between competing arguments, nor to opine on the correctness of other opinions on that medical question. The function is in every case to form and to give its own opinion on the medical question referred to it by applying its own medical experience and its own medical expertise."

1. Accordingly, the opinions of other experts, and indeed all the evidence before the Medical Assessor, have a bearing on the medical question before him, but only insofar as they assist him to fulfil his function. His task is defined by the referral, where it reflects the agreement of the parties.[13] The agreement of the parties in the present case can be traced reasonably well.

1. The case was originally pleaded in the Form 2 ARD as follows:[14]

"The applicant sustained an injury to her bilateral knees by way of a disease process and/or an aggravation of a disease process, as a result of her employment duties since approximately 2010. As a result of her knee injuries, the Applicant developed an altered gait causing a consequential injury to her lumbar spine.

In addition, or in the alternative, the Applicant experienced an acute period of onerous duties during November 2019, which caused a disease injury and/or aggravation of any such disease injury.

Further, and in the alternative, the Applicant sustained injury (in the lay sense) to her knee on 30 November 2019 whilst shopping at Bunnings. This injury (in the lay sense) was either a revelation of the work-related injury, or alternatively consequentially caused by the work-related injuries (due to weakness, pre-disposition).

The date of injury is the date of the first incapacity being 3 December 2019 (deemed)"

1. The claim was amended on 7 August 2024 when Consent Orders were issued by Member McAdam in the following terms:[15]

"By and with the consent of the parties, the Commission determines:

1. Amend the Application to Resolve a Dispute to allege date of injury as 21 November 2019 (deemed) instead of 3 December 2019.
2. Amend the Application to Resolve a Dispute to allege injury to back in addition to the injuries already pleaded.
3. Award for the applicant in respect of injury to left knee and consequential condition right knee.
4. Award for the respondent in respect of injury to and/or consequential condition of lumbar spine/back.
5. Matter remitted to President for referral to a Medical Assessor to assess:

(i) Date of injury: 21.11.19 (deemed)

(ii) Method of assessment: Whole person impairment

(iii) Body parts: Left lower extremity (knee);

(iv) Documents to be sent to the Medical Assessor:

• The Application to Resolve a Dispute;
• The Reply;
• An Application to Admit Late Documents dated 1 August 2024."

1. The referral provided for a copy of Member McAdam's Certificate of Determination to be attached. It can be seen that the claim regarding the right knee was expressly agreed to be a consequential condition, and that the date of injury was altered to 21 November 2019 (deemed). Thus, whilst the referral was for an assessment of both knees and scarring, Ms Roy's submission that the right knee had been referred as an "injury" was misconceived, with respect.

(a) means personal injury arising out of or in the course of employment,

(b) includes a disease injury, which means-

(i) a disease that is contracted by a worker in the course of employment but only if the employment was the main contributing factor to contracting the disease, and

(ii) the aggravation, acceleration, exacerbation or deterioration in the course of employment of any disease, but only if the employment was the main contributing factor to the aggravation, acceleration, exacerbation or deterioration of the disease,..."

1. The right knee condition was expressly referred as a consequential condition. A consequential condition is a medical condition that has developed as a direct result of a primary workplace injury. A common example thereof is a digestive disorder caused by ingestion of medication. Another is an overuse syndrome.[16] Proof of a consequential condition does not have to comply with the above definition.
2. The cause of Ms Roy's consequential condition however was difficult to identify within the evidence.

1. Ms Roy spoke only about symptoms in her left knee in her first statement of 27 March 2020. In a second statement dated 13 April 2022,[17] the only reference to her right knee appeared at [22] of her 13 April 2022 statement. She said:

"I do note that in November 2016 I had a fall on her [sic] right knee. After taking some time off work and some conservative treatment, I recovered very well."

1. Ms Roy gave precise and detailed evidence in these two statements about the onset and treatment of her left knee problem. In a third statement dated 21 February 2024, Ms Roy sought to discuss the dispute notices and the report of Dr Machart, the employer's medical expert. When doing so, Ms Roy employed the term "knees" when discussing that opinion, and her statement contained more advocacy than fact.[18] The only reference specifically to her right knee in that statement was at [44]:

"44. I also note Mr Machart does not believe my lumbar spine and right knee issues to be consequential to my left knee injury. As mentioned above, he instead attributed this to a pre-existing degenerative condition."

1. As noted, the claim in the ARD form also referred to an event at Bunnings. In her statement of 27 March 2020 Ms Roy explained that on 30 November 2019, whilst she was shopping at Bunnings, Wollongong, she felt a sharp pain in her left knee "almost like I had twisted my leg." Ms Roy sought treatment from her general practitioner (GP), Dr Shah at Better Care Medical Centre, who sent Ms Roy home to rest after being told that she had pains "in my left knee."[19]

1. Dr Patrick in his report of 28 November 2022[20] took a history that whilst undertaking her duties, Ms Roy "became aware of significantly increasing pain at both knee [sic], particularly the left knee." Dr Patrick noted Ms Roy's allegation that she had suffered a disease injury "to her bilateral knees" as a result of the nature and conditions of her employment, and noted that Ms Roy had consulted Dr Shah. Dr Patrick also noted the event at Bunnings on 21 November 2019. He said:[21]

".... Sophie Roy was at Bunnings pushing a trolley and she.... felt increase with left knee pain when pushing the trolley. There had also been actually a fall on to her right knee in November 2019 while working but after taking some time off work she recovered very well."

1. This latter history was incorrect, and it would seem that Dr Patrick had confused the right knee injury of 2016 as occurring in 2019. Dr Patrick attached an MRI report of the right knee which had been taken on 14 December 2016, the injury having occurred, as reported by Ms Roy above, in "November 2016."

1. An entry in the clinical notes of Dr Shah dated 1 December 2016 confirmed that Ms Roy had pain and swelling on the lateral aspect of her right ankle following an event two weeks earlier when she had caught her right ankle on a football net.[22] The entry noted that she improved with the right ankle but "now has pain behind right knee - only on wt bearing, since 3 days..." Dr Shah's note of 6 December 2016 was that Ms Roy felt the right knee was "getting better" and there were no further entries regarding the right knee. Dr Shah noted the Bunnings episode on 2 December 2019, stating:[23]

"...was pushing a heavy trolley at bunnings on Saturday, felt twisted the left knee while doing so, has pain on the medial aspect of left knee only on weight bearing..."

1. For the respondent, on 14 March 2023 Dr Frank Machart took a history that Ms Roy had developed pain in her right knee through "favouring" around December 2022.[24] He noted that Ms Roy had not had any X-rays. On examination of the right knee he noted:

"Lesser swelling (than the mild swelling in his left knee examination). Tender predominantly medially. Full extension through to 120° flexion. No ligament laxity."

1. As to the right knee, Dr Machart diagnosed "clinically, osteoarthritis. She has not had any investigations." He was unable to give an assessment of the right knee, saying:

"Could not be assessed without x-rays. There is osteoarthritis. Osteoarthritis is governed by definition of joint space. Physical features evident to me do not display features of measurable impairment."

1. Thus, an analysis of the evidence leaves the factual basis for the agreement between the parties that Ms Roy had suffered a consequential condition in her right knee difficult to establish. Ms Roy herself did not suggest that her right knee was implicated by the duties she was required to do as a security officer around St Mary's Cathedral. Her more general and argumentative statement of 21 February 2024 did nothing to dispel that difficulty, as its probative value was reduced by her advocacy and imprecision.
2. We are however constrained to find the basis of the agreement, as was the Medical Assessor.
3. Ms Roy, whilst submitting erroneously that the Medical Assessor was required to assess the impairment to the right knee on the basis that it had been injured, suggested that his reference to the "non-injured" right knee should be read as meaning that the Medical Assessor thought he was dealing with a consequential condition.
4. With respect we do not hold that view. The approach taken by the Medical Assessor was to assess the left knee. Whilst he referred to "knees" in the brief history he took, he prefaced that by saying that "Ms Roy told me" and he did not thereafter mention the right knee at all in the history that he took of the injury.
5. He noted under 'present treatment' that Ms Roy was not having any treatment for her right knee and that she did not trust her right knee, in which she had frontal pain.
6. As we have noted, in his summary the Medical Assessor accepted that pre-existing osteoarthritis in the left knee had been aggravated without specific injury, and he also noted that Ms Roy had "progressively started developing symptoms in her right knee."
7. Whilst the Medical Assessor did find that there was 0% whole person impairment for the right knee, his comment in dealing with Dr Patrick's report we find to be unequivocal when he referred to "the non-injured knee". His comments that standing and walking on the non-injured knee were not risk factors for osteoarthritis were clearly identifiable as being an opinion as to causation, namely, that the right knee had not been affected as a consequence of the left knee injury. His comments at that point as to the accepted risk factors (age, obesity, sex etc) further underline that conclusion. Moreover, we are not persuaded that the Medical Assessor would necessarily appreciate the legal distinction between an injury and a consequential condition. We note that even counsel for Ms Roy did not notice the terms of the Certificate of Determination defining the right knee injury as being consequential.
8. The Medical Assessor has accordingly fallen into error by trespassing onto the area of causation, and ignoring the terms of the referral. His reasons amounted to a finding that there was no injury or consequential condition to the right knee as a result of the injury to the left knee on the deemed date of 21 November 2019. It follows that the MAC must be revoked regarding the right knee assessment.
9. Doing the best we can with the evidence, we infer that the parties' agreement that Ms Roy had suffered a consequential condition was based on the assumption that she must have developed symptoms in her right knee as a result of favouring her injured left knee.

1. That being the case, the next question concerns whether she has any assessable impairment as a result of that consequential condition. The only opinion that supported such a finding came from Dr Patrick. However, the basis for that opinion was that Ms Roy was suffering from a mild collateral ligament laxity, which he assessed at 3% WPI.[25] We note that Dr Patrick did not mention such laxity in his physical examination, and we are not sure of the basis for that assessment.[26]
2. We also note that Dr Machart tested for collateral ligament laxity, as did the Medical Assessor, and neither specialist found such pathology. As noted above, the Medical Specialists said "...both knees are coronally and sagittally stable," and Dr Machart found "no ligament laxity."
3. We would note that in the presence of osteoarthritis it would be unusual to find the presence of ligament laxity. On the evidence we concur with the opinions of Dr Machart and the Medical Assessor that the appropriate diagnosis is that of osteoarthritis, and that the cause of Ms Roy's symptomatology was the aggravation of osteoarthritis present in the right knee due to the onset of the left knee injury.
4. In that regard we note the results of the MRI scan taken on 15 December 2016, which showed, amongst other pathology, the presence of "patella-femoral osteoarthritis with extensive exposed bone over the lateral patella facet and moderate partial wear over the inferior lateral trochlear sulcus."[27] Although that pathology appears to have remained quiescent when Ms Roy's left knee became symptomatic some years later, it is not surprising, with the added strain on the right knee following the onset of those symptoms, and particularly following the total left knee replacement surgery on 8 April 2021, that the right knee would have become symptomatic.
5. The Medical Assessor said with regard to the assessment of impairment for osteoarthritis:[28]

"Imaging is not supplied to make an assessment of the right knee on the basis of osteoarthritis. Impairment is not assessable on the basis of range of movement or diagnosis based estimate."

1. Ms Roy alleged that the Medical Assessor had not utilised the range of motion methodology in assessing her knees, but a perusal of his findings on physical examination demonstrates that this submission too was misconceived, as he did measure the range of motion, which was from 0 degrees to 130 degrees. Table 17-10 at page 538 of AMA 5 provides:

Deformity measured by femoral-tibial angle; 3° to 10° valgus is considered normal

1. It can be seen that Ms Roy has no entitlement based on a range of motion methodology as her range of motion was more than that which qualified under Table 17-10.
2. We note that the Medical Assessor was alive to the fact that there was no relevant imaging to make an assessment of the right knee on the basis of osteoarthritis. However, although the matter had been referred to him on the basis of Dr Patrick's opinion of collateral ligamentous laxity, his obligation was to use his own experience and expertise to make the assessment that had been referred to him. He was aware that a certain type of imaging was required in order to assess an osteoarthritic knee and he had the power under s 324 of the 1998 Act to call for the same. S 324 provides relevantly:

"324 Powers of medical assessor on assessment

(1) The medical assessor assessing a medical dispute may -

(a) consult with any medical practitioner or other health care professional who is treating or has treated the worker, and

(b) call for the production of such medical records (including X-rays and the results of other tests) and other information as the medical assessor considers necessary or desirable for the purposes of assessing a medical dispute referred to him or her, and

(c) require the worker to submit himself or herself for examination by the medical assessor.

(3) This section extends to the assessment of a medical dispute in the course of an appeal or further assessment under this Part.

(4) A medical assessor hearing the appeal or who is assessing the matter by way of further assessment has all the powers of a medical assessor under this section on an assessment of a medical dispute.

1. The Appeal Panel considered that the most efficacious way of conforming with the referral would be to exercise that power ourselves. Accordingly, we issued the following direction:

1. Pursuant to s 324 (1)(b) of the 1998 Act, the Medical Appeal Panel calls for the production of x-rays as set out below which it considers necessary for the purposes of assessing the medical dispute referred to the Medical Assessor and appealed to the Panel.
2. Chapter 3 of the NSW Workers Compensation Guides for the evaluation of Permanent Impairment provides:

3.19 Impairment due to arthritis (AMA5 Section 17.2n, pp 544-45) following a work-related injury is uncommon, but may occur in isolated cases. The presence of arthritis may indicate a pre-existing condition and this should be assessed and an appropriate deduction made (see Chapter 1).

3.20 The presence of osteoarthritis is defined as cartilage loss. Cartilage loss can be measured by properly aligned plain x-ray, or by direct vision (arthroscopy), but impairment can only be assessed according to the radiologically determined cartilage loss intervals shown in AMA5 Table 17-31 (p 544). When assessing impairment of the knee joint, which has three compartments, only the compartment with the major impairment is used in the assessment. That is, measured impairments in the different compartments cannot be added or combined.

3.21 Detecting the subtle changes of cartilage loss on plain radiography requires comparison with the normal side. All joints should be imaged directly through the joint space, with no overlapping of bones. If comparison views are not available, AMA5 Table 17-31 (p 544) is used as a guide to assess joint space narrowing.

3.22 One should be cautious in making a diagnosis of cartilage loss on plain radiography if secondary features of osteoarthritis, such as osteophytes, subarticular cysts or subchondral sclerosis are lacking, unless the other side is available for comparison. The presence of an intra-articular fracture with a step in the articular margin in the weight-bearing area implies cartilage loss.

3.23 The accurate radiographic assessment of joints always requires at least two views. In some cases, further supplementary views will optimise the detection of joint space narrowing or the secondary signs of osteoarthritis.

1. Accordingly the Medical Appeal Panel calls for properly aligned plain xray of the right knee as described above."
2. Regrettably the imaging we were supplied with did not comply with the above specifications. However, the imaging did confirm the presence of osteoarthritis in Ms Roy's right knee. The Appeal Panel accordingly determined that the matter should be determined by use of Chapter 1.23 of the Guides, which provides:

Given the range, evolution and discovery of new medical conditions, these Guidelines cannot provide an impairment rating for all impairments... In situations where impairment ratings are not provided, these Guidelines suggest that medical practitioners use clinical judgment, comparing measurable impairment resulting from the unlisted condition to measurable impairment resulting from similar conditions

with similar impairment of function in performing activities of daily living.' The assessor must stay within the body part/region when using analogy.

The assessor's judgment, based upon experience, training, skill, thoroughness in clinical evaluation, and ability to apply the Guidelines criteria as intended, will enable an appropriate and reproducible assessment to be made of clinical impairment."

1. The Appeal Panel determined that the condition of Ms Roy's right knee is such as to warrant a finding that she probably has a cartilage interval of 3mm, which entitles her to an assessment of 7% lower extremity impairment which equates to 3% WPI. Table 17-31 at page 544 of AMA 5 provides relevantly:

Whole Person (Lower Extremity) [Foot] Impairment (%)

Table 17-31 Arthritis Impairments Based on Roentgenographically Determined Cartilage Intervals

1. TEMSKI is a mnemonic for "table for the evaluation of minor skin impairment." The criteria are set out at Table 14.1 of the Guides, the footnote of which reads:

"This table uses the principle of 'best fit'. You should assess the impairment as to the whole skin system against each criteria [sic] and then determine which impairment category best fits (or describes) the impairment..."

"A scar may be present and rated as nought percent WPI.

Note that uncomplicated scars for standard surgical procedures do not, of themselves, rate an impairment."

"Scarring TEMSKI: This is assessed according to SIRA, page 74, Table 14.1. On the basis of the surgical wound being consistent with the surgery undertaken, a good colour match and barely distinguishable without trophic change, 0% whole person impairment is assessed for Scarring TEMSKI".

1. Table 14.1 is divided into five columns which set out the requisite criteria for a finding of either 0%, 1%, 2%, 3-4% and 5-9% WPI. A common criterion to an entitlement of 1% and above, is "Claimant is conscious of the scar(s) or skin condition." A 0% criterion is if "Claimant is not conscious or is barely conscious of the scar(s) or skin condition."
2. Similarly, a common criterion to an entitlement of 1% and above is that there is a colour contrast with the surrounding skin as a result of pigmentary or other changes. If the scar is of a "good colour match with surrounding skin, and the scar... Is barely distinguishable", 0% WPI applies, as does a situation where a claimant is unable to easily locate the scar.
3. Ms Roy submitted that the Medical Assessor fell into error because he did not consider, as we understood the submission, whether the claimant was conscious of the scar. Ms Roy's submission that an assessment can only be given where "the objective clinical signs must be measured subjectively against the worker" was not accompanied by any reference to authority and it may be that Ms Roy was simply commenting on the structure of Table 14.1. Be that as it may, there is no such requirement. A Medical Assessor, as noted above, is obliged to apply the principle of "best fit." The findings he made were consistent with the criteria in the 0%: of the Table and there was no reason on the evidence to suspect that Ms Roy was conscious of her scar, as nowhere in her three statements, nor in the histories given to Dr Patrick, Dr Machat and the Medical Assessor himself did she make any comment about the scar.
4. We find no error in the assessment of scarring (TEMSKI).

1. Section 323 of the 1998 Act provides relevantly:

"(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....."

1. It is well accepted that there are three steps to be considered in the application of this section. In Cole v Wenaline Pty Ltd[29] Schmidt J held that firstly the level of impairment caused by the subject injury should be assessed. In the present case it was 20% for the left knee, and that assessment has not been challenged. Her Honour 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.[30] 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."

1. When assessing the second stage - whether a proportion of the baseline impairment was due to the previous injury, pre-existing condition or abnormality (in Cole it was a previous injury) - it is necessary for a Medical Assessor to identify the relevant condition, and the date of onset.
2. Ms Roy argued that the Medical Assessor had failed to identify her underlying condition, and that "in truth" there was none. The Medical Assessor made a finding of "bilateral constitutional degenerative arthritis" to explain his deduction at [11] of the MAC. At [6] he noted the conclusions in the MRI scan of 23 December 2019, and concluded at [7] that Ms Roy had "aggravated pre-existing osteoarthritis" to the left knee, and that she had progressively started developing symptoms in her right knee. Dr Machart concurred with that diagnosis in his report of 14 March 2023. Dr Patrick referred to the relevant imaging studies, which he said were "attached in chronological order." The MRI scan of 23 December 2023 was not attached, but was with Dr Shah's notes.[31] Dr Patrick thought that the relevant pathology in the left knee consisted of the left knee posterior horn medial meniscal tear with chondral defect to the medial condyle and bone marrow oedema. He advised that Ms Roy had suffered a disease injury to her bilateral knees as a result of the nature and conditions of her employment over the 10-year period up to 21 November 2019. Whilst he did not identify the nature of the disease, but we confirm that the results of the MRI indicated the presence of osteoarthritis.
3. Thus we are satisfied that it is probable that osteoarthritis was the disease process that was aggravated by Ms Roy's duties. It was certainly accepted in the description of the injury within the Form 2 ARD as being the "aggravation of a disease process."
4. However, recent authority now holds that it is not enough to simply identify the pre-existing condition. Ms Roy submitted that if the osteoarthritis had been contracted during the 10 years of her employment, then it could not be described as a pre-existing condition and there would have been no deduction for it at all. This is undoubtedly correct, and a "relevant date" must also be established.
5. In Craigie v Faircloth & Reynolds Pty Ltd[32] Johnson J stated from [36]:

"36 In Cullen, Beech-Jones J (as his Honour then was) said (at [46]) that to establish a pre-existing condition for the purpose of s.323(1) WIM Act, there must, at a 'relevant date', be an actual condition, although it may be asymptomatic. His Honour observed in Cullen (at [56]) that the Medical Appeal Panel had not identified 'any point in time much less prior to his employment commencing when Mr Cullen may have first developed osteoarthritis albeit asymptomatic'.

1. Beech-Jones J identified the error in Cullen at [57]:

'... the MAP concluded that once it was established that Mr Cullen had osteoarthritis that had a 'constitutional pathology' then it automatically followed that it was a pre-existing condition. In this case that approach was erroneous in law and constitutes an error of law on the face of the record (and that is the case irrespective of whether the condition had to pre-date the commencement of his employment or some later time)'."

1. The evidence indicates that the relevant date was probably during that 10 year employment period. There is no evidence that Ms Roy's osteoarthritic condition existed prior to her employment with the respondent, and therefore it is likely that its onset occurred whilst Ms Roy was so employed. Accordingly, there is no pre-existing condition.
2. The third consideration is to assess the degree to which the pre-existing condition actually contributed to the baseline assessment. In doing so attention must be paid to the evidence, including the medical evidence, but also all the evidence that is relevant to this exercise. At [30] of Cole, Schmidt J said:

"Section 323 does not permit that assessment to be made on the basis of an assumption or hypothesis, that once a particular injury has occurred, it will always, 'irrespective of outcome', contribute to the impairment flowing from any subsequent injury. The assessment must have regard to the evidence as to the actual consequences of the earlier injury, pre-existing condition or abnormality...."

1. In this regard that we find the Medical Assessor has also erred. He has applied a test which is not authorised by the legislation. His statement that without the pre-existing condition there would have been no assessable impairment is irrelevant to the statutory task he was required to carry out. Further, it is hypothetical and speculative.
2. Although he took a history of the onset of the left knee condition whilst Ms Roy was working at St Mary's Cathedral, and although he recorded that he had been told by Ms Roy that she thought she had developed osteoarthritis as a result of being a security guard, the Medical Assessor did not engage with that history in his reasons. Ms Roy had been working at different sites as a security guard for the respondent for over 10 years, and had been in the industry for 20 years. There was no evidence that her left knee had ever caused any symptoms prior to the work she was required to do at the Cathedral, about which Ms Roy said in her statement of 21 February 2024:

"25. I have worked at numerus sites with huge sets of stairs, but navigating those premises were nothing compared to the Cathedral.

1. Until starting at the Cathedral I had never worked at a site with so many stairs and such a large area to patrol."
2. That evidence was before the Medical Assessor and he made no attempt to explain how it was that Ms Roy had managed to work for such a long period in the same industry without any left knee symptoms. On its face that history supported the proposition that the nature of Ms Roy's duties had made the left knee symptomatic.
3. Moreover, the Medical Assessor's generalisations as to age weight and sex lacked any explanation. He did not advise what it was about Ms Roy's age, weight and sex, that led him to believe that those matters were causative, if that is what he meant. His statement at [11] required some explanation, as it did not reach acceptable grammatical English. To repeat, he said:

"...In the absence of pre-existing degenerative arthritis in both knees likely the consequence of age, weight and sex, the nature and conditions of Ms Roy's employment not have been associated with the development of symptoms from the osteoarthritis and consequently impairment."

1. In El Masri v Woolworths Ltd[33] Campbell J said at [50]:

"...Although ... Wingfoot does not necessarily apply to this case because it was a case where there was a statutory obligation to give reasons, and in this case the obligation to give reasons is implied by the general law as explained in _Campbelltown City Council v Vegan[34]_what their Honours said at [55] of Wingfoot must be applicable. Basically, the statement of reasons must explain that actual path of reasoning in sufficient detail to enable a court to see whether the opinion does or does not involve any error of law."

1. Accordingly the MAC will be revoked to reflect these findings.
2. For these reasons, the Appeal Panel has determined that the MAC issued on 9 October 2024 should be revoked, and a new MAC should be issued. The new certificate is attached to this Statement of Reasons.

This Certificate is issued pursuant to s 328(5) of the Workplace Injury Management and Workers Compensation Act 1998.

The Appeal Panel revokes the Medical Assessment Certificate of Medical Assessor Rob Kuru and issues this new Medical Assessment Certificate as to the matters set out in the table below:

Chapter, page, paragraph, figure and table numbers in AMA5 Guides

deductions pursuant to S323 for pre- existing injury, condition or abnormality

Sub- total/s % WPI (after any deductions in column 6)

Total % WPI (the Combined Table values of all sub-totals)

[3] This a common abbreviation of the term "aggravation, exacerbation, acceleration or deterioration" of a disease injury.

[4] (1990) 10 MVR 570.

[5] [2010] NSWSC 78.

[6] [2024] NSWSC 497.

[7] [2023] NSWPICMP 499.

[8] [2003] NSWWCCPD 27.

[10] [2024] NSWCA 178.

[11] Western Sydney Local Health District v Chan [2015] NSWSC 1968 at [13].

[12] [2013] HCA 43; (2013) 252 CLR 480.

[13] Skates v Hills Industries Ltd [2021] NSWCA 142.

[16] See e.g. Kumar v Royal Comfort Bedding Pty Ltd [2012] NSWWCCPD 8, Zahrouni v BSV Tyre Recycling Australia Pty Ltd [2025] NSWPICPD 3.

[17] Appeal pages 55 and 62 respectively.

[29] [2010] NSWSC 78 at [38].

[30] The "baseline" impairment as defined in [5], above.

[32] [2021] NSWSC 1211.

[33] [2014] NSWSC 1344.

[34] [2006] NSWCA 284.