DETERMINATION OF APPEAL PANEL	
	
CITATION:	State of NSW (Central Coast Local Health District) v Page [2022] NSWPICMP 495	
		
APPELLANT:	State of New South Wales (Central Coast Local Health District)	
		
RESPONDENT:	Colleen Page	
		
Appeal Panel		
		
MEMBER:	Richard Perrignon	
		
MEDICAL ASSESSOR:	Gregory McGroder	
		
MEDICAL ASSESSOR:	John Brian Stephenson	
		
DATE OF DECISION:	1 December 2022	
		
CATCHWORDS: 	wORKERS cOMPENSATION - Appeal from assessment of wrists; whether commencement of employment was the relevant date for determining whether there was a pre-existing condition; whether a deduction was available for pre-existing arthritis; Held – Medical Assessment Certificate confirmed. 

BACKGROUND TO THE APPLICATION TO APPEAL
1.	The appellant employer appeals from the Medical Assessment Certificate of Medical Assessor Burns dated 19 September 2022. Medical Assessor Burns assessed a 21% whole person impairment (11% right upper extremity; 11% left upper extremity), making no deduction for a pre-existing condition. The appellant alleges error in respect of the failure to consider or make a deduction for pre-existing arthritis.
2.	The worker, Ms Page, responds to the appeal. She had worked for the appellant as a pharmacy porter from about 2004 until her retirement in March 2020. She had ceased work in March 2020 prior to undergoing surgery to both hands. In a statement filed with the Personal Injury Commission (Commission), she explained that on her return to work from holidays on 8 October 2018, she was required to carry heavy boxes in the course of her duties, and suffered symptoms in her wrists and hands.
3.	In these proceedings, she claimed compensation for impairment of the whole person as a result of injury on 8 October 2018 (deemed date). In her Application to Resolve a Dispute, she alleged ‘exacerbation of bilateral wrist osteoarthritis’. She relied on the assessment of Associate Professor Hope, which had formed the basis of her claim. He diagnosed permanent ‘aggravation’ of previously asymptomatic arthritis. The difference between the two forms no part of the grounds of appeal.
4.	The left and right upper extremities were initially referred to Medical Assessor Wong. The referral was in the standard form. It specified the date of injury as 8 October 2018, notwithstanding the fact that it had been pleaded as a deemed date in the Application to Resolve a Dispute. On 19 December 2021, the Medical Assessor assessed a 10% whole person impairment (5% left upper extremity; 5% right upper extremity) as a result of injury on 8 October 2018. In doing so, he deducted one half for ‘severe pre-existing osteoarthritis at both thumbs’ which had been demonstrated by CT scan performed on 15 January 2019. His assessment necessarily implied a finding that the osteoarthritis had been present prior to injury 8 October 2018.
5.	Ms Page appealed from his assessment, on the basis that permanent impairment compensation had been claimed as a result of a ‘disease injury’ which was not in dispute, the assessor had mischaracterised the injury as one occurring on a specific date, and ‘the Medical Assessor has not considered or weighed the relative contribution of the Applicant’s employment history to the osteoarthritic changes in her hands’ evidenced by scans. 
6.	On 10 May 2022, a Medical Appeal Panel (constituted differently from this Panel) noted the submissions of the appellant, but upheld her appeal on a different basis. The Panel found that it was the intention of the parties that the assessment be made on the basis of a deemed date of injury, that the referral did not reflect this, and that accordingly the assessment of Medical Assessor Wong, made in accordance with the strict terms of the referral, was a nullity. In accordance with the suggestion of Adamson J in Skates v Hills Industries Limited [2020] NSWSC 837 at [73], the Panel reverted to the President in order to obtain a referral which reflected the parties’ agreement as to the date of injury, and which therefore reflected the dispute which the Commission had power to determine.
7.	On 26 July 2022, the left and right upper extremities were referred to Medical Assessor Burns for assessment of whole person impairment as a result of injury on 8 October 2018 (deemed date). This reflected the deemed date of injury pleaded.
8.	As indicated, he assessed a 21% whole person impairment (11% right upper extremity; 11% left upper extremity), making no deduction for a pre-existing condition. 
9.	The appellant employer alleges that the failure to make a deduction demonstrates error and the application of incorrect criteria, because the assessor failed to take into account evidence of the existence of a constitutional arthritic condition of the hands, simply indicating that there were no symptoms of arthritis prior to the commencement of employment.
10.	It does not otherwise allege any error in the making of the assessment. The Appeal Panel’s review ‘is limited to the grounds of appeal on which the appeal is made’: s 328(2).
11.	The Appeal Panel conducted a preliminary review of Medical Assessor Burns’ medical assessment in the absence of the parties and in accordance with the NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment (4th edition) (the Guidelines). 
Submissions
12.	The parties made written submissions. To address a lack of clarity in the grounds of appeal relied on by the appellant, and to afford the respondent procedural fairness, directions were made for supplementary submissions. These were complied with. All the parties’ written submissions have been taken into account. It is unnecessary to repeat them in full. A brief summary follows.
13.	The appellant submits that the assessment demonstrates error and the application of incorrect criteria in the following ways:
(a)	By identifying the commencement of employment as the date (‘relevant date’) before which a pre-existing condition must be found to have existed in order to make a deduction pursuant to s 323 of the Workplace Injury Management and Workers Compensation Act 1998.
(b)	By failing to identify the deemed date of injury as the relevant date for the purposes of s 323.
(c)	By failing to find that osteoarthritis existed prior to the deemed date of injury, and considering the degree, if any, to which that pre-existing condition was contributing to impairment.
14.	In its supplementary submissions, the appellant employer advanced an alternative argument without leave, namely that if the relevant date was the commencement of employment, the assessor failed to have regard to the degree to which arthritis prior to that date continues to contribute to impairment. As we have found that the relevant date was not the commencement of employment, it is unnecessary to consider the alternative submission.
15.	The respondent submits as follows in reply:
(a)	Section 323 does not require a deduction to be made in every case where a date of injury is deemed by operation of s 16 of the Workers Compensation Act 1987.
(b)	The Medical Assessor concluded that there was no evidence of arthritis existing prior to the commencement of employment. This was consistent with the history taken, and there is no radiological evidence to the contrary.
(c)	In the absence of radiological evidence to that effect, there was no basis for concluding that there was a pre-existing condition justifying a deduction pursuant to s 323.
Consideration
16.	Section 323 requires a “deduction for any proportion of the impairment that is due to any previous injury … or that is due to any pre-existing condition or abnormality”.
17.	In Cullen v Woodbrae Holdings Pty Limited [2015] NSWSC 1416, it was accepted (though the issue was not in dispute) that, where the disease provisions apply and a disease is alleged to have been contracted, or aggravated, over a period of time, a deduction for a pre-existing condition under s 323 is only available where the assessor finds that the condition existed before that period of time, even if it was asymptomatic. It is not enough to show a mere predisposition or susceptibility to contracting the disease or condition: per 
Beech-Jones J at [46].
18.	In Craigie v Faircloth & Reynolds Pty Ltd [2021] NSWSC 1211, Johnson J set aside a decision of an Appeal Panel which had confirmed a deduction of one-fifth made by a Medical Assessor for a pre-existing condition. In that case as in this, the date of injury relied on was a deemed date, which reflected the first onset of symptoms. In its decision, the Panel had failed to specify the relevant date before which the pre-existing condition must have been found to have existed. Accordingly, Johnson J was satisfied that insufficient reasons had been given, and agreed in the exercise of discretion to make the orders which had been sought by consent, setting aside the decision.
19.	In this case the appellant employer submits that, in assessing whole person impairment as a result of injury on 8 October 2018 (deemed date), the Medical Assessor was required to consider whether osteoarthritis existed in the thumbs prior to the deemed date of injury, and if so, to consider whether that condition was contributing to the permanent impairment assessed. It says that he erred in considering only whether the condition existed prior to the commencement of employment.
20.	Medical Assessor Burns diagnosed at [7] moderately severe osteoarthritis in the 1st CMC joint of her left and right thumbs, noting that the worker had been treated with bilateral trapeziectomy and suspension plasty, with some residual symptomatology in both hands.
21.	In the material before him was a report of radiologist Dr Khandelwal concerning an X-ray of both hands performed on 15 November 2018. Dr Khandelwal reported, among other things:
‘Moderate to advanced osteoarthritic changes are demonstrated in bilateral 1st CMC joints with loss of joint space and marginal osteophytes, worse on the right.’
22.	Also in the material before the Medical Assessor was a report of radiologist Dr Chim concerning a CT scan of both hands conducted on 15 January 2019. Dr Chim reported:
‘Advanced osteoarthritic changes are demonstrated in few of the small joints of both hands and wrists with joint space narrowing and marginal osteophytes. The changes are more pronounced in bilateral 1st CMC, 1st interphalangeal and DIP joint of bilateral 2nd to 5th digits.’
23.	The Medical Assessor did not refer to either report, but he was not required to refer to all the evidence. It is highly likely that he had regard to the documentary evidence before him, including these reports. We are not satisfied that he failed to take into account radiological evidence of the existence of arthritis in 2019. He commented in detail on the assessment of Associate Professor Hope, whose report referred to the X-ray results. We are comfortably satisfied that the Medical Assessor was well aware that there was radiological evidence of advanced arthritis in the thumbs by November 2018.
24.	In our view, the advanced nature of the arthritis evidenced by the scans, including the presence of osteophytes, compelled an inference, had it been necessary to decide the issue, that arthritis existed in both thumbs prior to 8 October 2018. 
25.	The Medical Assessor did not decide that issue. He took a history at [4] of the onset of symptoms in both thumbs on 8 October 2019 [sic, 2018], after commencing more onerous duties than previously for a relatively short period of time. The applicant’s statement disclosed that these duties had commenced on 8 October 2018, when she returned to work after several months of holidays. 
26.	The Medical Assessor noted that the thumbs had been previously asymptomatic, and that the worker was unaware of any arthritis in them, though she had been aware of asymptomatic arthritis her fingers.
27.	At [10b] he gave the following reasons for making no deduction in respect of any pre-existing condition:
‘I noted that she had been working as a pharmacy porter for 15 years. There was no evidence within the documentation of pre-existing impairment in either the left thumb or the right thumb before she commenced her work as a pharmacy porter. Therefore no deduction would be appropriate.’
28.	His first sentence suggests that he intended ‘pre-existing’ to mean prior to the commencement of employment, which he put at 15 years prior to the cessation of duties in March 2019 – that is, in 2004. He made this clear at [10c], when dealing with the assessment of Dr Silva – emphasis added:
‘I note that he then made a one half deduction due to pre-existing osteoarthritis. I note that as this is a deemed date of injury and she first commenced work with this employer 15 years previously I cannot state that there is any pre-existing arthritis, which may have been present before those 15 years. Therefore, I cannot see that a deduction can be made.’
29.	As indicated, in her Application to Resolve a Dispute, the applicant alleged injury by way of an exacerbation of osteoarthritis. Associate Professor Hope, whose assessment had formed the basis of her initial claim, diagnosed an aggravation. He described the mechanism of injury in the following way:
‘On 8 October 2018, this pre-existing osteoarthritis was permanently aggravated after a period of repetitive lifting heavy boxes at work in the pharmacy.’
30.	Having regard to the pleading and to the report of Associate Professor Hope with other medical evidence, the injury alleged consisted of aggravation and exacerbation of a pre-existing condition of arthritis. The allegation that arthritis had been aggravated and exacerbated at work necessarily implied an admission that the arthritis had existed prior to the onset of symptoms on 8 October 2018, of which Ms Page gave evidence in her statement. That did not, of course, amount to an admission that the aggravation or exacerbation predated the commencement of employment in 2004. 
31.	Taking into account also her statement evidence, Ms Page was alleging that the increased lifting duties required of her on 8 October 2018, when she returned to work from holidays, aggravated and exacerbated pre-existing asymptomatic arthritis.
32.	In her submissions to the previous Appeal Panel, Ms Page’s solicitors described this allegation as one of a ‘disease injury’. More precisely, it is an allegation of the aggravation or exacerbation of a disease. On the applicant’s own statement and medical evidence, that exacerbation actually occurred, and became symptomatic, on 8 October 2018.
33.	The central issue for our determination is when, in the circumstances of this case, does s 323 require that a condition existed, before a deduction can be made for the degree, if any, to which that condition contributes to permanent impairment.
34.	The date of injury specified in the referral for assessment reflects the date of injury as pleaded: 8 October 2018 (deemed date). The reference to a deemed date is a reference to the date on which the relevant legislation deems the injury to have occurred. Deemed dates of injury are specified by ss 15, 16 and 17 of the Workers Compensation Act 1987. Of those, s 16 governs injuries consisting in the aggravation or exacerbation of a disease. Relevantly, it deems such injuries to have occurred on the date of first incapacity or the date of claim.
35.	The claim was made by letter dated 10 March 2021. We infer that the worker has relied on the first date of incapacity as being the deemed date of injury. There seems to have been no objection to that course.
36.	This is not a case where the worker has alleged that a disease was caused by the nature and conditions of employment over many years, or that injury consists of a series of exacerbations which occurred from the commencement of employment up to the deemed date of injury. The medical and statement evidence relied on by the worker details aggravations or exacerbations that occurred on the deemed date of injury itself – namely, 8 October 2018.
37.	In those circumstances, it is our view that the date before which a condition must be found to have existed in order for s 323 to make a deduction available is the date on which the aggravations or exacerbations occurred. That date is 8 October 2018. 
38.	In considering whether osteoarthritis existed prior to the commencement of employment in 2004, the Medical Assessor addressed the wrong issue, and took into account an irrelevant matter. That demonstrates error on the face of the certificate. In failing to consider whether the arthritis existed prior to 8 October 2018, he failed to consider a relevant matter. That also amounts to demonstrable error. For those reasons, the Medical Assessment Certificate must be set aside. This implies no criticism of the Medical Assessor, who appears to have interpreted the allegation of injury as one of a series of exacerbations from the commencement of employment, which is commonly the case.
Assessment
39.	Apart from the failure to make a deduction, no error was alleged in respect of the quantum of Medical Assessor Burns’ assessment. 
40.	Having regard to the advanced nature of the arthritis demonstrated on scans in November 2018 and January 2019, the Panel is comfortably satisfied that there was arthritis in both thumbs prior to injury on 8 October 2018. It remains for the Panel to consider what, if any, deduction ought be made to take account of that pre-existing condition.
41.	A deduction is only available in respect of such a condition if it currently contributes to the assessed impairment. To make that finding, the assessed impairment must be greater by reason of the pre-existing condition than it would otherwise have been. As Campbell J put it in Ryder v Sundance Bakehouse [2015] NSWSC 526 at [45], ‘the Panel must be satisfied that but for the pre-existing abnormality, the degree of impairment resulting from the work injury would not have been as great’. 
42.	In this case, arthritic conditions of both thumbs were treated by trapeziectomy and suspension plasty at the hands of Dr Marchalleck on 28 August 2018 (left) and 25 July 2020 (right). The operation reports and reports of subsequent consultations are before us. In both cases, the trapezium bone was removed, together with one third of the proximal trapezoid. This was done in order to remove all arthritic tissue. Suspension plasty was performed by suspending the metacarpal joint from the index finger, to compensate for the loss of the trapezium.
43.	With removal of the arthritic tissue, arthritis ceased to exist in the thumbs. Dr Burns’ examination disclosed no evidence of persisting arthritis. There is no basis for any finding that it exists, or that it continues to contribute to impairment.
44.	Dr Silva considered that pre-existing arthritis continued to contribute to impairment, because there was some impairment due to surgery, which itself was made necessary by the pre-existing arthritis. He omitted to consider the test in Ryder. 
45.	In our view, it is not possible to find that the impairment is greater by reason of the pre-existing arthritis than it otherwise would have been, because there is no evidence that the surgery would have been necessary by the time of the assessment, but for the aggravation and exacerbation of arthritis on 8 October 2018, which rendered the underlying condition symptomatic. To put it in the terms used in Ryder, the Panel is not satisfied that, ‘but for the pre-existing abnormality, the degree of impairment resulting from the work injury would not have been as great’. As the test in Ryder is not satisfied, no deduction is available, and a further examination is unnecessary.
Conclusion
46.	The Panel finds that the Medical Assessor failed to identify correctly the relevant date for the purpose of determining whether a deduction was available pursuant to s 323. Though that amounts to demonstrable error, it has made no difference to the assessment because, for the reasons given, no deduction is available in any event. 
47.	In those circumstances, the appropriate course is to confirm the assessment of 21% whole person impairment (11% right upper extremity; 11% left upper extremity). For reasons which differ from those of Medical Assessor Burns in respect of the operation of s 323 only, his assessment is confirmed.