Andrews v Warrigal Care

DETERMINATION OF APPEAL PANEL
CITATION:	Andrews v Warrigal Care [2025] NSWPICMP 827
APPELLANT:	Maree Andrews
RESPONDENT:	Warrigal Care
APPEAL PANEL
MEMBER:	Catherine McDonald
MEDICAL ASSESSOR:	Drew Dixon
MEDICAL ASSESSOR:	Alan Home
DATE OF DECISION:	23 October 2025
CATCHWORDS:	WORKERS COMPENSATION - Workplace Injury Management and Workers Compensation Act 1998; review of Medical Assessment Certificate (MAC); assessment of permanent impairment following hip replacement; obligations of Medical Assessor with respect to other material in the file; State of New South Wales v Kaur; section 323 deduction where previous treatment disclosed in general practitioner’s records; Vitaz v Westform (NSW) Pty Ltd, Ryder v Sundance Bakehouse, Southwell v Qantas Airways Limited considered; Held – MAC revoked.

BACKGROUND TO THE APPLICATION TO APPEAL

On 10 July 2025 Maree Andrews lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Yiu-Key Ho, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on 17 June 2025.
Ms Andrews relies on the following grounds of appeal under s 327(3)(c) and (d) 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.
The President’s 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 but limited to the grounds of appeal on which the appeal is made.
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.
The assessment of permanent impairment is conducted in accordance with the SIRA NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment, 4^th ed 1 March 2021 (the Guidelines) and the American Medical Association Guides to the Evaluation of Permanent Impairment, 5^th ed (AMA 5).

RELEVANT FACTUAL BACKGROUND

Ms Andrews was employed by Warrigal Care as an aged care worker. On 1 December 2020 she suffered a twisting injury to her right knee when she was pushing a trolley around a corner. Her injury was diagnosed as an aggravation of osteoarthritis. Dr Bhimani undertook a right total knee replacement in May 2022.
The injury is pleaded in the Application to Resolve a Dispute as the aggravation of a disease with a deemed date of 1 December 2020, though the injury description is limited to the event pushing a trolley on that day.
The Medical Assessor assessed a fair result from total knee replacement surgery, resulting in an assessment of 20% WPI. He deducted one-half under s 323, and issued a MAC certifying that Ms Andrews had 10% WPI as a result of the injury.

PRELIMINARY REVIEW

We conducted a preliminary review of the original medical assessment in the absence of the parties and in accordance with the Procedural Direction PIC7.
As a result of that preliminary review, we determined that it was not necessary for Ms Andrews to undergo a further medical examination because there is sufficient information in the file to determine the appeal.

EVIDENCE

We have 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.
The parts of the MAC that are relevant to the appeal are set out, where relevant, in the body of this decision.

SUBMISSIONS

Both parties made written submissions. They are not repeated in full, but we have considered them.
In summary and in submissions prepared by Mr Pecelj of counsel, Ms Andrews submitted that the Medical Assessor failed to give adequate reasons and did not expose the actual path of reasoning to his opinion. The statements relied on to support that submission were the Medical Assessor’s statement that his assessment “more or less concurs” with A/Prof Hope and his statement that “we are not very sure about the contribution of the pre-existing condition”.
Ms Andrews’ second ground of appeal was that the Medical Assessor denied Ms Andrews procedural fairness and made a demonstrable error in that it was unclear what consideration he gave to her statements which “clearly acknowledge” that she was able to work without restriction, mow her lawns and walk and stand without restriction. She said that the Medical Assessor “failed to respond to a substantial argument”.
The third ground of appeal was that the Medical Assessor failed to take relevant considerations into account, being the histories from A/Prof Hope and Dr Bhimani that Ms Andrews was functioning normally and had minimal discomfort before the injury. Ms Andrews’ fourth ground of appeal was that the “decision of the Medical Assessor” was unreasonable or plainly unjust when he expressed doubt as to the extent of the deduction then deducted 50%. She said that her substantive rights were affected, being permanent impairment compensation and a potential claim for work injury damages.
Ms Andrews’ submissions were supported by reference to authorities with respect to administrative decisions generally, rather than medical appeals under the 1998 Act.
Ms Andrews asked that she be re-examined.
In reply, Warrigal Care submitted that the Medical Assessor did have regard to the evidence in the file as well as the history taken at the examination. In response to Ms Andrews’ second argument that the Medical Assessor failed to disclose his path of reasoning, Warrigal Care said that the evidence in the file supported the existence of a significant pre-existing condition. It said that the Medical Assessor assessed a deduction based on objective findings and his own clinical judgement.
Warrigal Care said that the Medical Assessor engaged with Ms Andrews’ history, recording the detail she provided at the examination and that there was no failure to afford procedural fairness. It said that the Medical Assessor took account of the history in the file and that it should be assumed that he had read the material in the file. Warrigal Care said there was evidence that Ms Andrews had longstanding osteoarthritis, which was expressly acknowledged by A/Prof Hope and Dr Bhimani.
With respect to the submission that the Medical Assessor’s decision was unjust, Warrigal Care said that the Medical Assessor exercised his clinical judgement as he was required to do by the Guidelines and recognised the significance of longstanding degenerative changes. It said that Ms Andrews was seeking to cavil with the exercise of that clinical judgement but that did not amount to a demonstrable error.

FINDINGS AND REASONS

The procedures on appeal are contained in s 328 of the 1998 Act. The appeal is 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.
In Campbelltown City Council v Vegan[1] the Court of Appeal held that an 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] [2006] NSWCA 284.
In Queanbeyan Racing Club Ltd v Burton[2] the Court of Appeal held that an Appeal Panel is not limited to the ground held to have been made out by the delegate but may consider all grounds of appeal raised in the application. However, the panel is not permitted to look for errors which are not part of the grounds of appeal on which the appeal is made. We have only considered those grounds specifically raised by the appeal.
[2] [2021] NSWCA 304 at [26].

The MAC

The Medical Assessor recorded the history of the injury:
“Maree Andrews is now sixty five years old. She worked for Warrigal Care for eighteen years and injury was in 2020 and she was put on light duties for one year and then was medically discharged. The injury happened on the 1 December, 2020, she was pushing a heavy linen trolley negotiating a corner and end up twisting her right knee and with pain. She went to see her family doctor the next day and had x-ray, MRI scan and then started on physiotherapy. She was referred on to see Dr Bhimani and the consultation first visit was on the 10 March, 2021, three months later. The knee at that time was very stiff 10° to 70° and Dr Bhimani, based on the x-ray and MRI scan findings, recommended her to have total knee replacement with the opinion that it was a work injury aggravating the preexisting osteoarthritis. Ultimately surgery was done on the 16 May, 2022, fourteen months later in the public hospital but the outcome was not the best as the knee was constantly stiff. She had a long period of physiotherapy but no manipulation under anaesthesia and the condition became static in the last three years.”
The Medical Assessor said:
“She told me that even before the injury she knew that she had significant knee problem and has been on regular Tramadol at night time 100mgs for at least two years before the injury and in the patient file there was an x-ray done on the 22 May 2018, more than two years before the injury there was already severe osteoarthritic changes in the medial compartment of the right knee.”
Summarising the injuries and diagnoses, the Medical Assessor said:
“Maree Andrews has a twisting injury on the 1 December, 2020, aggravating the preexisting OA knee which shown already severe OA changes with x-ray in 2018. She ended up with total knee replacement but with an unsatisfactory outcome.”
The Medical Assessor assessed 20% WPI for a fair result. He said:
“My assessment more or less concurs with Dr Nigel Hope. I am different to Dr Rimmer as he gave more points for her pain and less points for deduction for flexion contracture as my examination is 15 and his is only 5 and that explains the difference in the result. But the most difficult point for this case is what is the contribution of pre-existing condition. Dr Nigel Hope put it as 0% and Dr Rimmer put it as 100%. I cannot agree with Dr Nigel Hope, even in his report he mentioned this is a case of WorkCover injury aggravating the pre-existing osteoarthritis and similarly from the treating surgeon Dr Bhimani. We know for sure the x-ray done in 2018, two years before the so called work injury there was already significant osteoarthritis with a lot of visits to the family doctor for knee pain. However I cannot agree with Dr Rimmer either for 100% deduction because despite pain patient carry onto work although she told me she was taking Tramadol every night for at least two years before the work injury so to me I think it is more appropriate to have a one half deduction as patient definitely had significant pre-existing problems which is much higher than the usual figures of 1/10 when we are not very sure about the contribution of pre-existing condition and that will leave behind a 10% whole person impairment only for the work injury dated the 1 December, 2020.”

Medical history

The notes from Ms Andrew’s general practitioner in Warrigal Care’s Reply begin in 2015, when she was prescribed anti-inflammatory medication to treat “OA”, the generally accepted abbreviation for osteoarthritis. On 3 December 2015 the general practitioner recorded that she had orthotics for “feet OA”. The name of the general practitioner is not recorded against the entries.
On 16 May 2018 the general practitioner recorded:
“Prev benign tumour on right knee- has had 2 surgeries- > 20 years ago
getting pains all along- getting worse over last 12/12
o/e scars medial side. mild swelling between scars. flexion to just about 90°
sensitive”
An X-ray was ordered and reported on 22 May 2018 as showing:
“Severe advanced osteodegenerative changes are noted at the right knee. There is predominant involvement of the medial tibial-femoral compartment. There is a bone-on-bone configuration. There is degenerative lipping internally and at the joint margin. Mild to moderate degenerative changes are noted at the patellofemoral compartment, with prominent osteophytes noted on the lateral view. The patellofemoral compartment is not significantly narrowed.”
The general practitioner prescribed Targin for night pain and Ms Andrews agreed to try conservative treatment rather than be referred to a specialist.
In July 2018 Ms Andrews sought to continue taking Targin, though she said that she needed to take Panadeine as well as Targin did not help as expected. The general practitioner prescribed Tramadol, an opioid pain medication. In October 2018 the general practitioner recorded that Ms Andrews was going very well with Tramadol, supplemented by Panadol. The doctor recorded that she “hardly takes Endone”.
On 5 March 2019 the general practitioner recorded:
“Been working continuously last fortnight- right knee has fared up
sl limping gait
has bone-on bone on rt knee
flexion to 90°
swollen.”
The doctor recommended analgesia and that Ms Andrews “slow down with work.” A medical certificate was provided.
On 12 April 2019 the general practitioner prescribed 100mg of Tramadol to be taken in the evening and 50mg to be taken in the morning as needed. Those prescriptions were repeated on 1 August 2019 and roughly monthly thereafter.
In January 2020 Ms Andrews had left knee pain and an X-ray showed osteoarthritis. In September 2020 the general practitioner prescribed Tramadol for osteoarthritis in Ms Andrews’ knees and hands.
On 4 December 2020 Ms Andrews gave a history of the injury to her right knee at work. The general practitioner’s note includes:
“noted past OA esp in the medial compartment of bone on bone configuration but she was working and managing her role ok
tramadol
- when she was pulling a linen trolley and turning she had to balance the force and her knee got twisted and she had pain. this has become worse in last few days
can last about an hr before it gets too much
interfering with sleep and is taking a lot more pain killers
- sl antalgic gait
some swelling
tender medial joint line
15 deg to about 80 deg ROM
hip ok
- adv add on IR tramadol
general measures
see Monday
cert done
aggravation of preexisting condition as per today's assessment but this can change if any new findings clinically as we go along - will monitor.”
Dr Nagaraj referred Ms Andrews to Dr Bhimani whom she saw for the first time on 10 March 2021. He diagnosed an acute exacerbation of arthritis in her right knee. Dr Bhimani said:
“On examination she has a varus deformity to a knee and she walks with a stiff knee antalgic gait. She has a large effusion. She has well healed surgical scars over the medial side of the knee from where she had a benign tumour removed in her 20s. She has a poor range of motion from 10-70° Her hip is not irritable. She is otherwise neurovascularly intact.
Her x-rays and MRI scans demonstrate severe medial compartment arthrosis which is bone-on-bone with an associated meniscal tear. She has mild arthritis of the lateral and patellofemoral compartment.”
Dr Bhimani agreed to arrange for Ms Andrews to have a total right knee replacement. In a report to Ms Andrews’ solicitor on 28 September 2021, Dr Bhimani wrote:
“2.     She tells me she had minimal discomfort in the knee prior to her injury, testimony to this is the fact that she was able to work and carry out her normal duties as well as recreational activities with no concern.
3.      Mrs Maree Andrews did have pre-existing arthritis in the knee but minimal symptoms. Her injury has precipitated severe pain and as such its caused both an aggravation and acceleration with progression of arthritis and associated symptoms.
4.      I feel her injury has brought forward the need for her to require a total knee replacement. The rationale for this is that prior to her injury she was actually managing the symptoms well, evidence by the fact that she was able to carry out all work duties and in recreational activities with minimal or no discomfort. Since her injury she has had severe knee pain and difficulty managing both her work and day-to-day activities.
…”
Warrigal Care’s insurer declined responsibility for surgery, based on Dr Rimmer’s opinion, which is summarised below. Dr Nagaraj attended a case conference on 11 June 2021 with Ms Andrews’ rehabilitation provider. He wrote:
“long discussion about what the independent doctor has advised
in my opinion, it is agreed that OA itself wasn't worsened by the fall but her ROM, ease of movement and functioning have gone down dramatically as a result
- for now, her surgery has been declined.”
The surgery was on 16 May 2022. Dr Bhimani told Dr Nagaraj on 28 July 2022 that:
“…She is now able to bend the knee more than she was able to do and do things like walk up and down a flight of stairs or pick things up off the floor these are activity which she has not been able to for over 4 years.”
That comment about Ms Andrews’ pre-injury capacity contrasts with that in the report to Ms Andrews’ solicitors. It suggests there was some limitation of function before the injury.

Ms Andrews’ statements

Ms Andrews’ first statement was dated 7 July 2021. She described the injury and its aftermath. She said:
“I note, by way of background, that I did have problems with my right knee many year ago. This would have been when I was around 19 or 20 years of age and I noticed a lump on my knee. I came under the care of various doctors and it would seem that a benign tumour was on my knee. This was removed once, but not effectively and then a second time by Dr Mahoney. My knee has been fine since that time, although in the last 8-10 years I have had some soreness in my right knee. I have consulted with my GP about this occasionally, however, I regard the knee as being largely symptom-free. I was able to work without restriction, mow my own lawns and it was not stiff or swollen. My sleep was fine and I was able to function and carry on with my life as normal.”
In her third statement dated 23 April 2024 Ms Andrews said:
“I also have pre-existing osteoarthritis and have consulted with my GP regarding the pain; however, the condition never had any impact on my functionality.
Prior to my work-related injury I faced no difficulties with the amount of walking or standing as required by my employment duties. I did experience pain in my leg prior to my work related injury. However, it is now much more frequent. As such, I am now taking Tramadol both of an evening and throughout the day. Prior to my work-related injury I would only take one tablet of an evening.”

Medico-legal reports

Ms Andrews’ solicitors asked her to see A/Prof Hope who reported on
23 August 2021. He began his report:
“This 61-year-old Care Service Employee had pre-existing right knee osteoarthritis as indicated on X-ray by the GP in 2019. However, this did not result in any functional loss. Full duties continued as a Care Service Employee involving constant walking and standing without symptoms. Right total knee arthroplasty would have been required in the next 10 years in any case but the work-related injury permanently aggravated and accelerated this pre-existing condition so that total knee arthroplasty is now required some 10 years sooner than would have normally been necessary.”
He also recorded:
“A benign tumour was resected from the knee at age 21 and re-resected at age 22. This is irrelevant. However, mild right knee pain occurred in 2019 and the GP performed an X-ray showing osteoarthritis. No treatment was required. A return to full duties as a Care Service Employee was possible consisting of constant walking and standing. There were no symptoms performing these duties and there was full function in the right knee.”

A/Prof Hope’s diagnosis was:
“The diagnosis is consistent with the mechanism of injury. The right knee was largely asymptomatic (even though there was pre-existing osteoarthritis) and the work-related event caused permanent and increased symptoms.”
He said:
“Employment with Warrigal Care and the workplace injury on 1 December 2020 is the main contributing factor to the permanent aggravation and acceleration.
Prior to the work-related event, the right knee was functionally normal as indicated by the ability to perform duties as a Care Service Employee involving constant walking and standing. There were no symptoms whilst performing these duties. The
work-related incident on 1 December 2020 caused a permanent deterioration in symptoms and a permanent deterioration in the ability to function.”
A/Prof Hope set out the same history in his report dated 3 July 2023. He assessed a fair result from total knee replacement surgery. Asked about the proportion due to previous injury, pre-existing condition or abnormality, A/Prof Hope said, without explanation, that there are no deductions.
Dr Rimmer saw Ms Andrews at the request of Warrigal Care. In his first report he diagnosed a “resolved/trivial aggravation pre-existing severe degenerative osteoarthritis of her right knee." He agreed that Ms Andrews required a right total knee replacement. He said that Warrigal Care’s insurer was not liable because she had been seeking medical attention for years about right knee degenerative arthritis and total knee replacement was inevitable.
Dr Rimmer assessed WPI in a report dated 7 December 2023. He agreed that Ms Andrews had a fair result from the knee replacement but said there was a “100% relationship between the pre-existing symptoms and disabilities she exhibits today”. Dr Rimmer said that 100% of the WPI was apportioned to her chronic pre-existing condition.

Consideration

Ms Andrews’ first argument was that the Medical Assessor failed to provide adequate reasons. The Medical Assessor is an administrative decision maker and the correct approach to review of his decision is described in the joint judgment in Minister for Immigration and Ethnic Affairs v Wu Shan Liang[3] where the High Court approved the statement of principle in a decision of the full Federal Court:
“… a court should not be concerned with looseness in the language nor with unhappy phrasing of the reasons of an administrative decision-maker. … the reasons for the decision under review are not to be construed minutely and finely with an eye keenly attuned to the perception of error."
[3] [1996] HCA 6, 185 CLR 259, 272.
In that regard, we consider that the Medical Assessor’s statement about the reports of independent medical examiners and the s 323 deduction (at [28] above) should be read in the following way. The Medical Assessor concurred with A/Prof Hope because his observations and measurements on examination were substantially the same as those by A/Prof Hope, who assessed a fair result under Tables 17-35 and 17-33 of AMA 5. Dr Rimmer assessed a good result, because some of his measurements were different to those made by the Medical Assessor. Turning to the s 323 deduction, the Medical Assessor said that A/Prof Hope’s failure to make a deduction was unwarranted, given the osteoarthritis and the visits to the general practitioner before the injury. Dr Rimmer’s deduction of 100% was excessive. The Medical Assessor said that one tenth was inappropriate, that deduction being relevant “when we are not very sure about the contribution of the pre-existing condition”. He considered that one half was appropriate.
The Medical Assessor is required to set out the path of his or her reasoning. In State of New South Wales (NSW Department of Education) v Kaur[4] (Kaur) Campbell J said:
“…In particular, it is obvious that approved medical specialists are required to decide disputes referred to them by the process of medical assessment. Even so, it is not necessary that approved medical specialists should sit as decision makers choosing between the competing medical opinions put forward by the parties. Essentially, the function is the same as that described by the High Court in Wingfoot Australia. That is to say, their function is in every case to form and give his or her own opinion on the medical question referred by applying his or her own medical experience and his or her own medical expertise. It is sufficient, as their Honours pointed out at [55], that:
‘The statement of reasons… explain the actual path of reasoning in sufficient detail to enable the Court to see whether the opinion does or does not involve any error of law’.”
[4] [2016] NSWSC 346 at [26].
We agree that the Medical Assessor did set out the path of his reasoning in the paragraph quoted at [28], except to the extent that he failed to fully explain the reason for a deduction of one-half, which we consider was excessive, for the reasons set out below.

Procedural fairness and relevant considerations

Ms Andrews’ second ground of appeal was that the Medical Assessor denied Ms Andrews procedural fairness because he did not have sufficient regard to her statements. The argument was supported by a reference to the statement in Rodger v De Gelder[5] (Rodger), citing Dranichnikov v Minister for Immigration and Multicultural Affairs[6] (Dranichnikov).
[5] [2015] NSWCA 211.
[6] [2003] HCA 26;77 ALJR 1088.
Ms Andrews’ reliance on Dranichnikov is not apt. That case concerned the failure to deal with a “substantial, clearly articulated argument relying on established facts”. In Wang v State of New South Wales,[7] the Court of Appeal said:
“The decision is not authority for the proposition that any failure to refer to any argument put to a trial judge amounts to error. It is necessary to engage with the nature and materiality of the argument in the context of the issues in the proceedings.”
[7] [2019] NSWCA 263.
In Allianz Australia Insurance Ltd v Cervantes[8] cited in Rodger, Basten JA said that Dranichnikov did not go “so far as to imply an obligation to consider every piece of evidence presented.”
[8] [2012] NSWCA 244; 61 MVR 443.
Rodger concerned the role of a medical review panel under the Motor Accidents Compensation Act 1999, which is different to that of a Medical Assessor under the 1998 Act. As Basten AJ pointed out in Lancaster v Foxtel Management Pty Ltd,[9] the statutory function is materially different.
[9] [2022] NSWSC 929 at [35].
Ms Andrews’ third ground of appeal was that the Medical Assessor failed to take into account relevant considerations, being medical reports in the file. The second and third grounds of appeal both convey a misunderstanding of the Medical Assessor’s task and can be dealt with together.
The Medical Assessor is tasked with determining the degree of WPI by undertaking an examination and preparing a report, based on his observations on the day of the examination and the relevant history and using his own clinical judgement.[10] He was not required to base his findings on Ms Andrews’ statements or other opinions in the file.
[10] Guidelines paragraph 1.6.
A Medical Assessor is alerted by the template to provide the reasons why his or her opinion differs from other opinions in the file. That enables the parties understand how and why a different result was reached. The fact that another assessor made a different observation on a different day should not influence the Medical Assessor’s opinion.
While Ms Andrews said she was able to work before the injury, that is not the only factor that the Medical Assessor was required to take into account. Her statements do not carry the same weight as the historical medical material in the file, nor do they have the status of “clearly articulated arguments”. We note that she worked a 60 hour fortnight which is less than full time.
Ms Andrews saw her general practitioner in 2018 complaining of pain in her right knee. An
X-ray showed osteoarthritis with bone on bone contact at that time. Ms Andrews’ general practitioner observed on 16 May 2025 that flexion of her right knee was “just about 90°”, conveying a significant restriction. Those findings mean that knee replacement was inevitable at some future time. Ms Andrews’ general practitioner prescribed strong pain medication in the form of Tramadol. The injury in December 2020 brought the need for surgery forward. Dr Bhimani was of the same opinion.
Ms Andrews argued that the Medical Assessor should have commented specifically on the opinions of A/Prof Hope and Dr Bhimani. We have explained above why he was not required to comment on the opinions in the file more than he did. We note the significant inconsistency between Dr Bhimani’s report to Ms Andrews’ solicitor dated 28 September 2021 that “she was able to work and carry out her normal duties as well as recreational activities with no concern” and his report to Dr Nagaraj dated 28 July 2022 where he said that Ms Andrews was able to walk up and down stairs and pick up objects from the floor, which she had not been able to do for four years.

The application of s 323

Ms Andrews argued that the Medical Assessor’s deduction of one half was unreasonable or unjust. We agree that the deduction was excessive. We have explained above why we do not agree with the submission that the Medical Assessor was unsure about the deduction.
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.
…”
In Vitaz v Westform (NSW) Pty Ltd[11] (Vitaz) Basten JA, with whom the other members of the Court agreed, rejected the contention that if a worker did not suffer symptoms from a
pre-existing condition and there was no rateable impairment before an injury, there would be no deduction under s 323. His Honour said:
“That opinion contained a legal assumption which is inconsistent with the approach adopted by this Court in, for example, D'Aleo v Ambulance Service of New South Wales (NSWCA, 12 December 1996, unrep) (quoted by Giles JA, Mason P and Powell JA agreeing, in Matthew Hall Pty Ltd v Smart [2000] NSWCA 284; 21 NSWCCR 34 at [30]-[32]and, more recently, by Schmidt J in Cole v Wenaline Pty Ltd[2010] NSWSC 78 at [13]). The resulting principle is that if a pre-existing condition is a contributing factor causing permanent impairment, a deduction is required even though the
[11] [2011] NSWCA 254 at [43].
pre-existing condition had been asymptomatic prior to the injury.”
In Ryder v Sundance Bakehouse (Ryder) Campbell J said:[12]
“What s 323 requires is an inquiry into whether there are other causes, (previous injury, or pre-existing abnormality), of an impairment caused by a work injury. A proportion of the impairment would be due to the pre-existing abnormality (even if that proportion cannot be precisely identified without difficulty or expense) only if it can be said that the pre-existing abnormality made a difference to the outcome in terms of the degree of impairment resulting from the work injury. If there is no difference in outcome, that is to say, if the degree of impairment is not greater than it would otherwise have been as a result of the injury, it is impossible to say that a proportion of it is due to the pre-existing abnormality. To put it another way, the Panel must be satisfied that but for the pre-existing abnormality, the degree of impairment would not have been as great.”
[12] [2015] NSWSC 526 at [45].
Southwell v Qantas Airways Limited[13] also concerned the extent of the deduction under s 323. Wright J considered Cole v Wenaline Pty Ltd and said:[14]
“Thus, it has been held, in cases such as Elcheikh v Diamond Formwork (NSW) Pty Ltd (in liq) [2013] NSWSC 365 at [126] (Schmidt J) and Secretary, Department of Communities and Justice v Lewandowski [2023] NSWSC 334 at [52] (Griffiths AJ), that what must be determined under s 323 involves, at least three enquiries:
·Firstly, what the extent of the resulting impairment is.
·Secondly, whether the pre-existing condition contributed to the impairment.
·Thirdly, if it did, what proportion of the impairment was due to the pre-existing condition.
In light of the construction referred to above, however, the formulation of the second of these three enquiries may, in a case such as the present, misdirect consideration, if it were thought that all that had to be established was that the pre-existing condition was causally related in some way to subsequent workplace injury and the impairment suffered as a result of that injury, without any part or portion of that level of impairment being due to the pre-existing condition and not the injury.”
[13] [2024] NSWSC 497.
[14] At [50]-[51].
After quoting the passage from Ryder set out above, Wright J said:
“Applying that approach, Campbell J concluded at [47]-[48] that the Panel in that case fell into jurisdictional error by failing in the circumstances of that case to address, inter alia:
1. whether the injury suffered in the workplace injury ‘was worse because of the pre-existing [degenerative disc condition or] abnormality’; and
2. ‘the means by which the pre-existing abnormality in the disc as found by the Panel contributed causally to the level of impairment, as opposed to the occurrence of the injury’ (emphasis added).
This approach is consistent with what was said in Vitaz at [43], when it is understood that the reference to ‘permanent impairment’ in the principle stated by Basten JA was a shorthand reference to the ‘level of [permanent] impairment’ as referred to later in that same paragraph. In other words, the principle in that case was to the effect that, even if a pre-existing condition was asymptomatic before a workplace injury but some portion of the level of impairment after the workplace injury was due to the pre-existing condition and not the injury, a deduction was required under s 323.” (emphasis in original).
The notes from Ms Andrews’ general practitioner show that she had very significant problems with her right knee from at least 2018. She had pain, for which she was prescribed strong medication, and her general practitioner observed a significant restriction of the range of motion on two occasions. The medical records can be contrasted with her statements about her abilities and the amount of medication she was taking. Her ingestion of opiate medication shows that the submission that she had minimal discomfort was inappropriate. Dr Bhimani’s statement about not being able to use stairs or pick up items from the floor for four years dates those significant disabilities to the time before the injury. It cannot be said that she was functioning normally. Those factors lead to the conclusion that a deduction of one-tenth was manifestly inadequate.
On the other hand, Ms Andrews had not been referred to a specialist and knee replacement had not been considered before the injury and she was continuing to work and to perform her full duties as an aged care worker, which involved heavy work such as manoeuvring the trolley that she was pushing at the time of the injury.
In addition, the injury itself was significant. The notes for 4 December 2020 record that Ms Andrews had pain which was interfering with her sleep and for which she was taking more painkillers. She had swelling and the range of movement was reduced to from 15 to 80°. The general practitioner prescribed IR (instant release) Tramadol.
The injury brought forward the inevitable need for knee replacement. In those circumstances, a deduction of one-half was excessive. We consider that the appropriate deduction is one quarter.
For these reasons, the Appeal Panel has determined that the MAC issued on 17 June 2025 should be revoked, and a new MAC should be issued. The new certificate is attached to this statement of reasons.

WORKERS COMPENSATION DIVISION

APPEAL PANEL

MEDICAL ASSESSMENT CERTIFICATE

Injuries received after 1 January 2002

Matter number:	W4370/25
Applicant:	Maree Andrews
Respondent:	Warrigal Care

This Certificate is issued pursuant to s 328(5) of the Workplace Injury Management and Workers Compensation Act1998.

The Appeal Panel revokes the Medical Assessment Certificate of Medical Assessor Yiu-Key Ho and issues this new Medical Assessment Certificate as to the matters set out in the table below:

Table - whole person impairment (WPI)

Body Part or system	Date of Injury	Chapter, page and paragraph number in NSW workers compensation guidelines	Chapter, page, paragraph, figure and table numbers in AMA 5 Guides	% WPI	Proportion of permanent impairment due to pre-existing injury, abnormality or condition	Sub-total/s % WPI (after any deductions in column 6)
Right lower extremity	1.12.2020	Chapter 3	Table 17-33, 17-35	20%	¼	15%
Total % WPI (the Combined Table values of all sub-totals)					15%

[2025] NSWPICMP 827

23 October 2025