1. On 28 February 2025 Kim Shoemark, the appellant, lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Dr Donald Cawthorne, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on

31 January 2025. 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 Guidelines) 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 22 October 2024 this matter was referred to the Medical Assessor for a WPI assessment relating to the injury to the left lower extremity and scarring (TEMSKI) which occurred on

20 July 2020. 2. Ms Shoemark was employed as a process controller at the time of the injury. She injured her left leg whilst squatting down and reaching across to her left and working on a machine. 3. She underwent a total left hip replacement in February 2023. 4. The Medical Assessor assessed 14% WPI.

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. As a result of that preliminary review, the Appeal Panel determined that it was not necessary for the worker to undergo a further medical examination because the error established concerned the application of s 323 of the 1998 Act, in respect of which the relevant evidence was already before us, and no useful purpose would have been served in a re-examination of the appellant.

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 the Medical Assessor said:[1]

"She continued to work, though had ongoing issues due to her pain so was ultimately reviewed by Dr Andrew Clout, Orthopaedic Surgeon on 1/11/2021 for further investigation. The hip on Xray was noted as 'preserved' and therefore an MRI was organised as too [was] a cortisone injection into the iliopsoas tendon. Ms Shoemark states this did not improve her symptoms.

MRI scan was reported as showing 'chondral degeneration in her weight bearing surface' and therefore based on this, along with her ongoing pain symptoms and clinical examination, Ms Shoemark underwent a left total hip replacement in February 2023 at Calvary Private Hospital in Wagga"

1. In describing Ms Shoemark's present symptoms the Medical Assessor said:[2]

Left hip/buttock: Aching pain most of the time, worse at the end of a busy day. Pain sometimes at the end of the scar. Keeps her up at night. Less pain than before the operation but still present.

Difficulty with stairs - has to pull self up using arms/railings. Can do 30 fights of 15 steps per day but worn out by the end.

Difficulty putting on shoes and socks due to reduced flexibility and. [sic] Has to sit down to get dressed.

1. As to Ms Shoemark's social activities the Medical Assessor noted:

Can still make bed and vacuum but with more difficulty than before.

1. In the findings of the physical examination the Medical Assessor said:

"Scar: 12cm scar, posterior approach. Skin coloured. No Tethering."

1. At 8F the Medical Assessor identified a previous pre-existing condition as being "Left Hip Degeneration."
2. In explaining his calculations at [10b] the Medical Assessor set out his assessment for rating of hip replacement results as required by Table 17-34 of AMA-5 at page 548. He found a total of 85 points which equated with a "Good" result.
3. As to the scarring he said:

"SCARRING: Rated as 0% as there is good colour match, No trophic changes, No contour defect, not clearly visible in usual clothing. Table 14.1 p 74 SIRA guidelines."

1. The Medical Assessor noted that the good result he certified was:

"Similar to both Dr Ridhalgh and Dr Miniter's hip-rating results however Dr Ridhalgh has attributed 19% for a 'good' result where I have attributed 15% as per AMA-5 table 70-33 page 546. The deductions for pre-existing disease vary between examiners."

1. In explaining the deduction at [11] the following appeared:

"11 DEDUCTION (IF ANY) FOR THE PROPORTION OF THE IMPAIRMENT THAT IS DUE TO PREVIOUS INJURY OR PRE-EXISTING CONDITION OR ABNORMALITY

a) In my opinion the worker suffers from the following relevant previous injuries, pre-existing conditions or abnormalities:

(i) Pre-existing degeneration in the Hip

b) The previous injury, pre-existing condition or abnormality directly contributes to the following matters that were taken into account when assessing the whole person impairment that results from the injury, being the matters taken into account in 10a, and in the following ways:

(i) With the pre-existing degeneration the symptoms and rapid decline of Ms Shoemark's hip following the injury would be more likely.

1. The extent of the deduction is difficult or costly to determine, so in applying the provisions of s 323(2), I assess the deductible proportion as one tenth."

1. The appellant relied on three principal submissions.
2. The first related to the one-tenth deduction assessed by the Medical Assessor. The second regarded the 0% finding for scarring, and the third challenged the finding by the Medical Assessor that the hip replacement surgery had produced a "good result".

1. Ms Shoemark kindly reproduced the section. She referred to the finding that there had been left hip degeneration which constituted the pre-existing condition and the description by the Medical Assessor in [11] of the deduction as being attributable to "pre-existing degeneration in the hip."
2. Ms Shoemark noted the comment by the Medical Assessor that the most significant point of difference between the opposing experts, were that the deductions varied. It was submitted that the Medical Assessor "provided no comment as to the reasons for it."
3. We were referred to the comment by the Medical Assessor at [11] that it would be more likely that Ms Shoemark's hip would rapidly decline because of the pre-existing degeneration.
4. Ms Shoemark referred to the Medical Assessor's mention of an MRI scan at the time of the surgery as showing "chondral degeneration in her weight-bearing surface". It was submitted that a deduction could not be made without evidence identifying the pre-existing condition relevantly, and establishing when it occurred. We were referred in that regard to Liu v Buckley Group (Pty) Limited (in Liq) t/as Buckley Group (Pty) Limited (deregistered).[3]
5. Ms Shoemark submitted there was a difference between the existence of a pre-existing condition and a mere vulnerability, the latter not attracting the application of s 323.
6. We were referred to Cole v Wenaline Pty Ltd.[4]
7. We were referred to the opinions of Dr Ridhalgh and Dr Miniter, the experts retained for each party, and particularly the opinion of Dr Ridhalgh that there was no applicable deduction. It was submitted that the Medical Assessor had failed to provide reasons as to the difference between his assessment and those of the medical experts regarding the relevance of the degenerative pathology in the left hip.
8. We were referred to Ms Shoemark's statement and other materials before the Medical Assessor that showed that any pre-existing degenerative changes had been asymptomatic prior to the subject injury.
9. It was submitted that the Medical Assessor failed to engage with the question of causation. His reasons, Ms Shoemark submitted, did not go far enough and he had not engaged in the process of reasoning required when applying s 323. It was submitted that he did not explain why the deduction was difficult or costly to determine, nor did he give a basis for his reasoning that the previously asymptomatic degenerative change had caused any of the impairment.

1. Ms Shoemark submitted that the 0% rating was erroneous. We were referred to the opinion of Dr Ridhalgh and to Ms Shoemark's statement that she was self-conscious because of her scar. Error was alleged in that the Medical Assessor had not made any explanation as to why his assessment was different from that of Dr Ridhalgh or Dr Miniter. Ms Shoemark referred to Chapter 14.8 of the Guides, which required an assessor to provide detailed reasons as to why one particular category had been chosen over the others. It was submitted that the Medical Assessor had not provided any reasons, quite apart from any detailed reasons, for his assessment. He failed to adequately explain why his assessment diverged from that of

Dr Ridhalgh "other than by failing to take account of a relevant considerations (sic) (conscious of scar, able to locate scar and not usually visible with clothing)."

1. Ms Shoemark submitted that the Medical Assessor failed to take into account all the evidence when finding that the hip replacement surgery produced a 'good' result. We were referred to Ms Shoemark's statement in that regard and the findings by the Medical Assessor. It was submitted that he failed to give adequate reasons when he recorded that Ms Shoemark could walk for six blocks and failed to elaborate on his finding that

1. The respondent submitted that there was "an abundance of evidence" available, including that from the treating GP and treating orthopaedic surgeon, which, it submitted, "would assist with the determination of the deduction". It was submitted that a pre-existing degeneration in the hip had support because the Medical Assessor had examined

Ms Shoemark and reviewed all the evidence. There was thus no failure to properly assess the deduction. 2. We were referred to Ferguson v State of New South Wales[5] regarding the pre-eminence of the clinical observations during the consultation. It was submitted that the Medical Assessor in this case "gave pre-eminence to his own observations." He had exercised his own clinical judgment as to the significance of the matters reported to him and "did what he was entitled and legally obliged to do".

1. We were referred to Table 14.1 of the Guides and the various criteria applicable to the different categories of impairment. In particular the respondent reproduced the criterion relevant to a 0% rating and submitted that the comments by the Medical Assessor in explaining his assessment complied in the main with those criteria.
2. The employer submitted that the appeal was based on the dissatisfaction that the Medical Assessor had differed from the rating given by Dr Ridhalgh.

1. The respondent referred to the complaints and present symptoms recorded by the Medical Assessor and submitted that his finding of a good result from the surgery was in accordance with his explanation.

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[6] Schmidt J held:

"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 [subject] injury was. Secondly, whether a proportion of that impairment was due to the [previous injury, pre-existing condition or abnormality]. 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. Thus, firstly, the level of impairment, the 'baseline' impairment, caused by the subject injury should be assessed. In the present case it was 15% for the left lower extremity, and whilst that assessment has been challenged, it will be considered later in these reasons.
2. The second step is to enquire whether a proportion of that impairment was due to, in this case, Ms Shoemark's pre-existing condition. In order to do so, it is necessary to identify the condition in the light of the evidence. It is this step that is the subject of this aspect of

Ms Shoemark's appeal. 3. The Medical Assessor explained that the deduction he made was because Ms Shoemark was suffering from "pre-existing degeneration in the Hip." Further, he said that this condition directly contributed to the baseline impairment (to paraphrase the effect of the templated [11b] of the MAC) on the basis that:

"With pre-existing degeneration the symptoms and rapid decline of Ms Shoemark's hip following the injury would be more likely."

1. It can be seen that the Medical Assessor took into account the effect of the injury as a cause of Ms Shoemark's symptoms and the rapid decline of her condition. However he did not explain why he came to the conclusion that Ms Shoemark indeed was suffering from a pre-existing degeneration in the hip, and in this regard it would appear he has not, with respect, considered his decision in the light of the evidence.
2. Ms Shoemark commenced employment in May 2010 when she was about 37 years old. She worked both as a machine operator and then a process controller over her time with the respondent.
3. In her statement of 20 September 2024 Ms Shoemark said:[7]

"I commenced employment with Hyne Timber in about May 2010 as a machine operator in the timber mill before moving to work as a process controller. I worked as a process controller for the last 10 years of my employment. My duties involved lifting, calibrating checking, recording, reporting, cleaning and fixing machines. The main machine that I was responsible for was the Lineal High Grader.

8. My role was physically demanding in nature, and I was on my feet for most of the day. . ."

1. Ms Shoemark said at [12] that when she sustained her injury she was required "to squat down reach across to the left and twist my body to unscrew the printer plate."
2. Ms Shoemark described earlier injuries to her lumbar spine and her left and right ankle prior to the injury, but there was no suggestion that, prior to the incident of 20 July 2020, the condition of her hip had caused any symptomatology. There was self-evidently therefore no pre-injury imaging available to the Medical Assessor. His failure to advert to the evidence - particularly to both the demanding nature of the work and the fact that Ms Shoemark's left hip had been asymptomatic over 12 years - we regard as a significant omission and raises a strong inference that indeed the Medical Assessor has relied for his assessment on conjecture or hypothesis rather than the facts of the case.[8]
3. It would appear that the Medical Assessor (although it is by no means clear) may have been influenced by the imaging that was taken subsequent to the injury. The Medical Assessor referred to an X-ray whilst taking the history, and he noted that an MRI showed "chondral degeneration in her weight bearing surface."
4. The evidence shows that two X-rays were taken, the first on 17 September 2020,[9] some two months following the injury, and the second on 23 December 2021.[10] On 30 March 2022,

Dr Andrew Clout, the treating surgeon, commented that the X-rays "show a well preserved hip joint." Having considered this imaging, we concur. The 2021 X-ray showed "no significant degenerative changes" and certainly no arthritis was identified. However, by the time the MRI scan was taken on 14 June 2022,[11] a "focal full-thickness cartilage loss in the central weight-bearing hip with acetabular bone oedema" was identified. This evidence clearly points to a rapid decline of Ms Shoemark's hip following the injury, and to that extent we concur with the opinion of the Medical Assessor. However, this evidence also establishes that the development of Ms Shoemark's degenerative condition was post-traumatic. The fact that the hip joint was well preserved in December 2021, and that the MRI scan demonstrated a focal cartilage loss is evidence that is consistent with the post-traumatic development of her degenerative condition. The Medical Assessor was accordingly in error to describe that condition as "pre-existing." We would observe that the focal loss is more likely than not caused by post-traumatic arthritis. 5. Accordingly, we revoke the MAC in this respect. We agree with the respondent that there was an abundance of evidence available, but note it did not support that finding by the Medical Assessor.

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."

"14.8 The TEMSKI is to be used in accordance with the principle of 'best fit'. The assessor must be satisfied that the criteria within the chosen category of impairment best reflect the skin disorder being assessed. If the skin disorder does not meet all of the criteria within the impairment category, the assessor must provide detailed reasons as to why this category has been chosen over other categories."

"SCARRING: Rated as 0% as there is good colour match, No trophic changes, No contour defect, not clearly visible in usual clothing. Table 14.1 p 74 SIRA guidelines."

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. Ms Shoemark submitted that the Medical Assessor fell into error because he did not consider the opinion of her expert, Dr Ridhalgh, and did not explain why he assessed a 0% entitlement when Ms Shoemark had said in her statement that she was conscious of the scar.
3. Dr Ridhalgh stated in his report of 17 April 2024:[12]

"There is also an additional 1% for the scar that is thickened and easily identified."

1. In her statement, Ms Shoemark said:[13]

"I have a surgical scar from the surgery. The scar is 13 cm long and located on my left buttock. The scar is thick and noticeable. I am self-conscious of this scar."

1. The submission that the Medical Assessor did not address the opinion of Dr Ridhalgh was unaccompanied by any authority supporting that he should. Indeed, the opposite is true, as it is well-settled that such is not a function of a Medical Assessor. The following High Court dicta is often cited:[14]

"...The function of a Medical [Assessor] 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. Chapter 1.6a of the Guides provides that "assessing permanent impairment involves clinical assessment of the claimant as they (sic) present on the day of assessment..." The Medical Assessor had the advantage of a face-to-face consultation and of examining Ms Shoemark. His determination was very much a matter of discretion as both the footnote to Table 14.1 and Chapter 14.8 invites the Medical Assessor to determine which impairment category was the "best fit." The detailed reasons required by Chapter 14.8 are only required where the skin disorder does not meet all the criteria within the impairment category. The Medical Assessor found no trophic changes, no tethering and a good colour match. Moreover, there was no indication that Ms Shoemark indicated on assessment that her scar embarrassed her.
2. Accordingly, this ground is rejected.

1. Table 17-34 of AMA5 provides the criteria for rating the results of hip replacements:[15]

* Add the points from a, b, c, d, and e to determine and characterize the result of replacement. Source: Modified from Gross AE McDermott AGP, Lavoie MV et al.

The use of allograft bone in revision help arthroplasty. In: Brand R, ed. Proceeding of the Fourteenth Open Scientific Meeting of the Hip Society. St Louis, Mo: CV Mosby Co; 1987: 49; and Harris AH. Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. J Bone Joint Surg Am. 1969; 51A:741-742

1. Table 17-35 provides for the number of points be allocated for the assessment of WPI which, by Table 17-33, provides for a poor (less than 50 points), fair (52 -84 points) or good (85 -100) result. A poor result rates 30% WPI, a fair result rates 20% WPI, and a good result rates 15% WPI.
2. The difficulty with Ms Shoemark's submission is that there was unanimity between

Dr Ridhalgh (albeit that he erroneously allocated 19%), Dr Miniter and the Medical Assessor that she had achieved a "good" result. The assessment, as can be seen from a perusal of Table 17-34, is complex and multifactorial, and merely cavilling with matters of fact that may or may not have been relevant to the process in the face of that unanimity neither demonstrate error, nor the application of incorrect criteria. This ground is also rejected. 3. For these reasons, the Appeal Panel has determined that the MAC issued on

31 January 2025 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 Donald Cawthorne and issues this new Medical Assessment Certificate as to the matters set out in the Table below:

Chapter, page and paragraph number in NSW workers compensation guidelines

Chapter, page, paragraph, figure and table numbers in AMA 5 Guides

Proportion of permanent impairment due to pre-existing injury, abnormality or condition

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

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

[4] [2010] NSWSC 78.

[5] [2017] NSWSC 887.

[6] [2010] NSWSC 78 at [38].

[8] See e.g. ElCheikh v Diamond Formwork (NSW) Pty Ltd (in liquidation) [2013] NSW SC 365 and Cole.

[14] Sydney Local Health District v Chan [2015] NSW SC 1968 at [13] citing Wingfoot Australia Partners Pty Ltd v Kocak [2013] HCA 43.