1. On 26 May 2025 Cumberland City Council (the appellant) lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Dr Gregory McGroder, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on 28 April 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).

1. Aaron Sawyer (Mr Sawyer) suffered an injury to his right hand in the course of his employment as a labourer with the appellant as a result of the heavy and repetitive nature and conditions of his employment or specific duties required of his role.
2. Mr Sawyer commenced proceedings in the Personal Injury Commission (Commission) claiming 21% whole person impairment (WPI) pursuant to s 66 of the Workers Compensation Act 1987 (the 1987 Act) in respect of an injury to his right upper extremity deemed to have occurred on 13 April 2023.
3. The Medical Assessor examined Mr Sawyer on 22 April 2025. The Medical Assessor assessed 20% WPI of the right upper extremity as a result of the injury on 13 April 2023.

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 there was sufficient information on which to make a decision.

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. They are not repeated in full but have been considered by the Appeal Panel.
2. The appellant's submissions include the following:

(a) the Medical Assessor has applied the incorrect criteria in his use of

s 323 of the 1998 Act when calculating Mr Sawyer's level of WPI arising from the right upper extremity, and this amounts to a demonstrable error;

(b) the application of s 323 has been considered as in Cole v Wenaline Pty Ltd [2010] NSWSC 78 (Cole). The Medical Assessor erred by failing to properly apply the criteria of s 323, thereby causing the MAC to fall into demonstrable error;

(c) at page 2 of the MAC, the Medical Assessor noted that at age 21, Mr Sawyer fell from a skateboard and fractured both wrists. This involved the scaphoid and he had surgery with a good result;

(d) at page 5 of the MAC, the Medical Assessor has stated "I have not made a deduction for a pre-existing condition. I expect that the previous surgery involving the scaphoid joint would be in part responsible for the development of carpal tunnel syndrome and the osteoarthritis but I have found that there is no evidence of any impairment prior to him commencing work at Cumberland City Council and subsequently have not made a deduction.";

(e) the Medical Assessor made a demonstrable error and/or applied the criteria imposed by s 323 incorrectly as the above statement indicates that the Medical Assessor cannot find evidence to indicate the extent of existing impairment prior to the subject employment but does still accept that the preexisting condition would be in part responsible for the development of the respondent worker's current injury. It follows that the Medical Assessor accepts that the pre-existing surgery contributed to Mr Sawyer's current impairment flowing from his injuries, assessed by the Medical Assessor as 20% WPI;

(f) it is an incorrect interpretation of the authority to conclude that absent clear evidence of impairment prior to the subject injury, no deduction is applicable. The authorities set out above clearly demonstrate that the relevant question is not one requiring determination of the extent of impairment already existing or measured before the work injury occurred, but instead the determination of what contribution pre-existing factors have had to the current assessable impairment;

(g) accordingly, the Medical Assessor ought to have concluded that a deduction was appropriate, given the contribution of the pre-existing surgery on the worker's subsequent injury and impairment. Any failure to do so has been due to the application of incorrect criteria;

(h) the Medical Assessor's application of incorrect criteria has then led to the demonstrable error of the absence of a s 323 deduction;

(i) the authorities above make it clear that the appropriate process, once accepting that there was a preexisting condition that was relevant to the degree of permanent impairment in question, was for the Medical Assessor to then determine the 'deductible proportion' or otherwise, if it were too difficult or costly to determine the extent of the deduction, adopt a 10% deduction if it were not at odds with the available evidence;

(j) given that appropriate consideration was not given to this question, it is not entirely clear what the Medical Assessor's views on this point were, except to note that the previous surgery was 'in part responsible'. It is difficult to say what the extent of that responsibility would be;

(k) however, at minimum, the Medical Assessor ought to have applied the 10% presumed deductible proportion to account for the impact of the pre-existing surgery on Mr Sawyer's overall impairment, and in not doing so, has fallen into error;

(l) by reference to the above, the appellant submits that the s 323 deduction applied by Dr Kuru (sic) was at odds with the available evidence and a higher deduction ought to have been applied;

(m) the Medical Assessor erred by:

(i) adopting incorrect criteria in respect of the s 323 deduction, thereby failing to properly consider the extent to which the pre-existing surgery contributed to the current assessable impairment;

(ii) as a consequence, failing to consider the appropriate deductible proportion, or otherwise adopt the 10% presumed deduction, and

(n) for the reasons discussed above, the MAC contains demonstrable errors and is based on incorrect criteria within the meaning of s 327(3) of the 1998 Act.

1. The respondent's submissions include the following:

(a) s 323(1) of the 1998 Act stipulates that a deduction is to occur "for any proportion of the impairment that is due to any previous injury...or that is due to any pre-existing condition or abnormality";

(b) the appeal is misconceived because it is not enough for an injured worker, such as Mr Sawyer, to have sustained an injury prior to the work-related injury. As is clear from the terms of s 323 of the 1998 Act, a deduction can only be made for a proportion of the impairment that is due to any previous injury etc;

(c) for any deduction to take place, the enquiry is not a simplistic one wherein the only question to be asked is whether a worker may have had issues to the same body part that was being assessed. The proportion of the impairment itself must be due to his prior issues;

(d) the Medical Assessor was clearly cognisant of this requirement and applied the terms of the legislation correctly;

(e) in Cole Schmidt J made it clear at [30] that the "assessment must have regard to the evidence as to the actual consequence of the earlier injury, pre-existing condition or abnormality.";

(f) at [38] her Honour indicated that s 323 required "evidence be considered so that it could be determined, firstly, what the level of impairment after the second injury was. Secondly, whether a proportion of that impairment was due to the first injury. Thirdly, what that proportion was.";

(g) the Medical Assessor had regard to this requirement and determined there was no proportion of the impairment that was causally related to any pre-existing matters. Schmidt J, at no point, indicated a deduction must be made without such interrogation taking place;

(h) the appellant has not read the MAC as a whole. The Medical Assessor, at page 2 of the MAC, after noting the prior accident that occurred when Mr Sawyer, who was 57 years at the time of the medical assessment, was 21 years of age, indicated that Mr Sawyer "obtained a good result from this". The appellant has not referred to this portion of the Medical Assessor's reasons (did refer to it), and Mr Sawyer submits this fact i.e. that he had obtained a good result from the prior injury and surgery, demonstrates there was no evidence of impairment prior to the employment related injury and/or no evidence of contribution to the WPI assessed;

(i) accordingly, consistent with Cole, Ryder v Sundance Bakehouse [2015] NSWSC 526 Campbell J and also consistent with Southwell v Qantas Airways Limited [2024] NSWSC 497, in absence of evidence satisfying contributing to the impairment assessed, no deduction pursuant to s 323 can be undertaken;

(j) the appellant's submissions at 15 (e) and (f) above 4 are legally misconceived and directly contrary to the manner in which s 323 was to be applied. It is not an error for a Medical Assessor to have conducted his assessment pursuant to the legislation and Supreme Court authority;

(k) the appellant has submitted that a Medical Assessor must make a deduction without interrogating whether any proportion of the finally assessed impairment was contributed to by the pre-existing injury. This is plainly wrong;

(l) the Medical Assessor complied with the law and the appellant has not understood the requirements imposed upon the Medical Assessor or the task which he was bound by statute to undertake;

(m) Mr Sawyer also highlights the appellant's submissions seek to infringe upon the actual assessment undertaken by the Medical Assessor. The Medical Assessor undertook his assessment, as he was permitted and required to do, on the basis of his own medical assessment. This was appropriate and consistent with the plurality's comments in Wingfoot Australia Partners Pty Ltd v Kocak [2013] HCA 43. own medical experience and its own medical expertise.", and

(n) there is no error. The basis of the appeal is legally and factually incorrect.

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.
3. The Appeal Panel has reviewed the MAC and evidence in this matter.
4. The Appeal Panel notes that the subheading in the appellant's submissions reads "Application of a section 323 deduction for the cervical spine". We note that Mr Sawyer accepts the reference to the cervical spine is an administrative error and the Appeal Panel agrees that it ought to read "right upper extremity". The Appeal Panel also noted that paragraph 20 of the appellant's submission reads "By reference to the above, the appellant submits that the section 323 deduction applied by Dr Kuru was at odds with the available evidence and a higher deduction ought to have been applied". Dr Kuru was not the Medical Assessor in this matter, although is he a member of this Appeal Panel. The Appeal Panel regard reference to Dr Kuru is another administrative error and it ought to read "Dr McGroder".

1. The appellant submits that the Medical Assessor has made a demonstrable error and/or applied the criteria imposed by s 323 incorrectly. The appellant argues that the Medical Assessor could not find evidence to indicate the extent of existing impairment prior to the subject employment but accepts that the preexisting condition would be in part responsible for the development of Mr Sawyer's current injury. Therefore, the appellant submits that the Medical Assessor accepted that the pre-existing surgery contributed to Mr Sawyers's current impairment flowing from his injuries, assessed by the Medical Assessor as 20% WPI.
2. Accordingly, the Medical Assessor ought to have concluded that a deduction was appropriate, given the contribution of the pre-existing surgery on Mr Sawyer's subsequent injury and impairment.
3. Under "History Relating to the Injury" the Medical Assessor wrote:

"Mr Sawyer started working with Cumberland City Council as a labourer in 1991 and has worked there for 34 years. He was a labourer and worked in parks and gardens and on the roads. His work involved a good deal of physical activity involving the upper extremities which included using picks, shovels, jackhammers, leaf blowers, whacker packers and rollers. Over time he noticed pain at the base of his right thumb and his wrist and tingling into his thumb and adjacent fingers. He said that the tingling in his fingers would wake him at night and the pain at the base of his thumb became particularly severe. This was to the extent that he saw his GP, Dr Jenny Nguyen. She diagnosed carpal tunnel syndrome and osteoarthritis of the base of the thumb. An EMG confirmed severe carpal tunnel syndrome on the right and a MRI confirmed osteoarthritis of the CMC joint with subluxation and a large loose body.

He was subsequently referred to Dr Nick Smith, Hand Surgeon, who he first saw on 28 June 2023. He recommended surgery and this was carried out on 19 September 2023 in the form of a carpal tunnel release and a CMC implant arthroplasty. His recovery was complicated by an infection which settled with antibiotics. He had a period of hand therapy. He improved following this and he had less pain at the base of his thumb and less of the burning/tingling sensation into his thumb and adjacent fingers.

He had follow-up x-rays which demonstrated that the arthroplasty was in satisfactory position. He achieved reasonable function involving his wrist and thumb to the extent that he was able to return to his normal duties at the council".

1. Under "Details of any previous or subsequent accidents, injuries or conditions" the Medical Assessor wrote:

"At age 21 he fell from a skateboard and fractured both wrists. This involved the scaphoid and he had surgery performed by Dr Honner, Hand Surgeon, with screw fixation of the scaphoid bones. He obtained a good result from this.

In the past he fractured his right ring finger and has been left with a flexion deformity".

1. Under "Summary of injuries and diagnoses" the Medical Assessor wrote:

"Due to the nature and conditions of his work Mr Sawyer developed arthritic change over the base of the CMC joint along with carpal tunnel syndrome. He underwent surgery in the form of carpal tunnel release and an implant arthroplasty involving the CMC joint. He has achieved good function but has restriction of range of movement of his right wrist, his right thumb and on-going sensory impairment involving the distribution of the median nerve".

1. Under "Evaluation of Permanent Impairment" the Medical Assessor wrote:

"e. Is any proportion of loss of efficient use or impairment or whole person impairment, due to a previous injury, pre-existing condition or abnormality? no

1. If so, please indicate which body part/system is affected by the previous injury, preexisting condition or abnormality. N/A".

1. Under "Reasons for Assessment at 10 b the Medical Assessor wrote:

"I have not made a deduction for a pre-existing condition. I expect that the previous surgery involving the scaphoid joint would be in part responsible for the development of carpal tunnel syndrome and the osteoarthritis but I have found that there is no evidence of any impairment prior to him commencing work at Cumberland City Council and subsequently have not made a deduction".

1. In his statement dated 2 January 2025, Mr Sawyer wrote:

"By way of background, at the age of 21 I had surgery following a right scaphoid fracture requiring a screw fixation. I had a complete recovery following this surgery and had no restriction in the use of my hand following my require rehabilitation."

1. In a report dated 28 June 2023, Associate Professor Nicholas Smith, treating Hand and Wrist Surgeon, noted that Mr Sawyer has a background of open reduction of a scaphoid fracture by Dr Honnor when he was 21 years old.
2. In a report dated 5 September 2023, Associate Professor Smith wrote in answer to the question "Is the surgery required a direct result of the workplace injury that Aaron sustained on or about 13/04/2023?":

"This was probably the straw that broke the camel's back so to speak, however Aaron has been working as a very heavy worker using jackhammers and employed by the same employer for the past 34 years. I would say that the long period of use of heavy equipment and heavy activities in the workplace over a long period of time, has also caused the problem, though sometimes there is an injury such as described on 13 April, which was thought to precipitate significant deterioration of symptoms".

1. In a report dated 24 July 2024, Associate Professor Gumley, consultant Hand Surgeon noted that Mr Sawyer had worked for the appellant for approximately 34 years and for much of this time was using a jack hammer and doing a lot of jack hammering and shovelling. He noted that Mr Sawyer developed substantial right carpal tunnel syndrome. Associate Professor Gumley noted that at the age of 21, Mr Sawyer had surgery for a right scaphoid fracture requiring a screw fixation. Associate Professor Gumley assessed 21 % WPI. He wrote:

"No deduction is required for pre-existing conditions or abnormality, noting that the measured range of wrist motion has not been included since it is equal to his uninjured opposite side and is likely also to be related to a emote (sic) scaphoid injury".

1. In a report dated 7 November 2024, Dr David Pennington, consultant Hand and Plastic surgeon, noted under "Past Medical History":

"At age 21, he had a fall on both hands and sustained bilateral scaphoid fractures. They were treated with open reduction and compression screw fixation by Dr Richard Honner. The screws were removed six months later. He had no ongoing problems with his hands thereafter".

1. Dr Pennington was requested to consider whether the evidence "warrants you applying a deductible proportion to your assessment of permanent impairment due to the proportion of WPI which has resulted from any pre-existing injury, conditions and/or abnormality." Dr Pennington wrote:

"In my opinion, Mr Sawyer would not have suffered from the conditions he required treatment for at the same time and at the same age as they arose, were it not for his prolonged employment. Therefore, I apply no deduction".

1. Dr Pennington also commented on Associate Professor Gumley's report and wrote:

"However, Prof Gumley did not measure differences in ranges of active movement for the two wrists, stating that the right wrist had a similar range to the left. I found that there was a difference in wrist AROMs, which justifies a 9% Upper Extremity impairment rating for the right wrist. In my opinion, his scaphoid surgery at the age of 21 is not the cause of the difference in wrist AROMS, but is more likely due to the work­related pathology in his right hand, which required surgery and some immobilisation a known cause of wrist stiffness."

1. Dr Pennington then stated that in relation to the deductible proportion, he agreed with Associate Professor Gumley's application of no deduction.
2. Section 323 of the 1998 Act provides:

"(1) In assessing the degree of permanent impairment resulting from an injury, there is to be a deduction for any proportion of the impairment that is due to any previous injury (whether or not it is an injury for which compensation has been paid or is payable under Division 4 of Part 3 of the 1987 Act) or that is due to any pre-existing condition or abnormality.

(2) If the extent of a deduction under this section (or a part of it) will be difficult or costly to determine (because, for example, of the absence of medical evidence), it is to be assumed (for the purpose of avoiding disputation) that the deduction (or the relevant part of it) is 10% of the impairment, unless this assumption is at odds with the available evidence.

Note. So if the degree of permanent impairment is assessed as 30% and subsection (2) operates to require a 10% reduction in that impairment to be assumed, the degree of permanent impairment is reduced from 30% to 27% (a reduction of 10%).

(3) The reference in subsection (2) to medical evidence is a reference to medical evidence accepted or preferred by the medical assessor in connection with the medical assessment of the matter.

(4) The WorkCover Guidelines may make provision for or with respect to the determination of the deduction required by this section".

1. The approach to be taken in assessing the s 323 deduction was considered by the Supreme Court in Cole v Wenaline Pty Limited [2010] NSWSC 78 (Cole). Schmidt J said:

"29 ...The section is directed to a situation where there is a pre-existing injury, pre-existing condition or abnormality. For a deduction to be made from what has been assessed to have been the level of impairment which resulted from the later injury in question, a conclusion is required, on the evidence, that the pre-existing injury, pre-existing condition or abnormality caused or contributed to that impairment.

1. 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. The extent that the later impairment was due to the earlier injury, pre-existing condition or abnormality must be determined. The only exception is that provided for in s 323(2), where the required deduction 'will be difficult or costly to determine (because, for example, of the absence of medical evidence)'. In that case, an assumption is provided for, namely that the deduction 'is 10% of the impairment'. Even then, that assumption is displaced, if it is at odds with the available evidence.
2. ...That is a matter of fact to be assessed on the evidence led in each case".
3. At [38] of Cole, Schmidt said:

"38. What s 323 required, however, was that the evidence be considered, so that it could be determined, firstly, what the level of impairment after the second injury was. Secondly, whether a proportion of that impairment was due to the first injury. Thirdly, what that proportion was. Undoubtedly in undertaking this exercise, the medical members of an Appeal Panel must utilise their medical judgement, knowledge and experience. Nevertheless, all stages of the statutory exercise must be undertaken in the light of the evidence and without the making of assumptions not provided for by the section."

1. In Vitaz v Westform (NSW) Pty Limited [2011] NSWCA 25 the Court said at [43]:

"The resulting principle is that if a pre-existing condition is a contributing factor causing permanent impairment, a deduction is required even though the pre-existing condition had been asymptomatic prior to the injury. In the absence of any medical evidence establishing a contest as to whether the pre-existing condition did contribute to the level of impairment, the complaint about a failure to give reasons must fail. An approved medical specialist is entitled to reach conclusions, no doubt partly on an intuitive basis, and no reasons are required in circumstances where the alternative conclusion is not presented by the evidence and is not shown to be necessarily available."

1. In Ryder v Sundance Bakehouse [2015] NSWSC 526 Campbell J stated at [45]:

"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 resulting from the work injury would not have been as great."

1. The Guidelines at paragraphs 1.27 and 1.28 provide:

"1.27 The degree of permanent impairment resulting from pre-existing impairments should not be included in the final calculation of permanent impairment if those impairments are not related to the compensable injury. The assessor needs to take account of all available evidence to calculate the degree of permanent impairment that pre-existed the injury.

1.28 In assessing the degree of permanent impairment resulting from the compensable injury/condition, the assessor is to indicate the degree of impairment due to any previous injury, pre-existing condition or abnormality. This proportion is known as 'the deductible proportion' and should be deducted from the degree of permanent impairment determined by the assessor. For the injury being assessed, the deduction is 1/10th of the assessed impairment, unless that is at odds with the available evidence"

1. The Appeal Panel noted that neither of the independent medical examiners (IMEs) made a deduction for pre-existing condition.
2. The appellant submits that Cole makes "it clear that the appropriate process, once accepting that there was a pre-existing condition that was relevant to the degree of permanent impairment in question, was for the Medical Assessor to then determine the 'deductible proportion' or otherwise, if it were too difficult or costly to determine the extent of the deduction, adopt a 10% deduction if it were not at odds with the available evidence."
3. The Appeal Panel accepts Mr Sawyer's submission that this formulation of the appropriate process under s323 is misconceived. The appropriate process is not the consideration of whether "a pre-existing condition that was relevant to the degree of permanent impairment assessed" and then a determination by the Medical Assessor of the 'deductible proportion' or otherwise. Cole and the other authorities make it clear that the appropriate process in applying s 323 required evidence be considered so that it could be determined, firstly, what the level of impairment after the second injury was, secondly, whether a proportion of that impairment was due to the first injury and thirdly what that proportion was.
4. Mr Sawyer submits that the MAC must be read as a whole and the Medical Assessor, at page 2 of the MAC, after noting the prior accident that occurred when Mr Sawyer, was 21 years of age, indicated that Mr Sawyer "obtained a good result from this". Mr Sawyer submitted that the appellant had not referred to this portion of the Medical Assessor's reasons. This is incorrect as the appellant did refer to Mr Sawyer obtaining a good result from the prior in surgery at paragraph 11 of the appellant's submissions. Further, the fact that Mr Sawyer has a good result from the surgery does not mean that there was no evidence of impairment prior to the employment related injury or no evidence of contribution to the WPI assessed.
5. Although the part of the appellant's submissions concerning the appropriate process under

s 323 are misconceived, the appellant did submit that the Medical Assessor erred by failing to properly apply the criteria of s 323, thereby causing the MAC to fall into demonstrable error. 6. The appellant also submits that it is an incorrect interpretation of the authority to conclude that absent clear evidence of impairment prior to the subject injury, no deduction is applicable. The appellant argues that the authorities set out above clearly demonstrate that the relevant question is not one requiring determination of the extent of impairment already existing or measured before the work injury occurred, but instead the determination of what contribution pre-existing factors have had to the current assessable impairment. 7. The Medical Panel, therefore, considered whether the Medical Assessor properly applied the criteria in s 323. The Medical Assessor assessed the degree of impairment in the right upper extremity. The Medical Assessor then found that the appellant had a pre-existing injury, namely, a fracture of the scaphoid for which he had undergone surgery. The Medical Assessor was then required to determine whether a proportion of that impairment was due to the first injury. If so, the Medical Assessor was required to determine what that proportion was. 8. The Medical Assessor found that the previous surgery involving the scaphoid joint would be "in part responsible" for the development of carpal tunnel syndrome and osteoarthritis but did not adequately explain why this did not result in a proportion of the impairment assessed being caused by the pre-existing injury. The only explanation the Medical Assessor gave was that there was no evidence of any impairment prior to the applicant commencing work with the respondent. However, this explanation failed to take into account that a deduction can be made pursuant to s323 for a pre-existing condition that is asymptomatic. The Medical Assessor did not properly consider, in our view, whether the asymptomatic condition in the right wrist made a difference to the outcome in terms of the degree of impairment resulting from the work injury. 9. Although the Medical Assessor found no evidence of any impairment prior to the applicant commencing work with the respondent, he was still bound to consider whether the asymptomatic pre-existing injury caused a proportion of the impairment assessed. This was necessary, particularly, in view of the radiological evidence. The Medical Assessor reported that the MRI scan of the right wrist on 14 June 2023 showed:

"There is deformity and advanced arthrosis at the lateral wrist relating to the STT and 1st, 2nd CMC joints. This may relate to sequelae of previous trauma. There is a ganglion cyst in the flexor retinaculum superficial to the flexor tendons with 3rd-5th flexor tendinosis. Mild compressive changes relating to the median nerve in the carpal tunnel are noted".

1. The Medical Assessor noted that there was deformity and advanced arthrosis at the lateral wrist relating to the STT and first, second CMC joints. He was of the view that this may related sequelae of previous trauma. The only previous trauma identified was the fracture of the right scaphoid.
2. The Appeal Panel finds that the Medical Assessor erred by failing to properly apply the criteria of s 323 and the failure to properly apply the criteria of s 323 was a demonstrable error. The ground of appeal is made out.
3. The Appeal Panel reviewed the evidence. Taking into account the MRI scan dated 14 June 2023, the Appeal Panel is satisfied that the pre-existing injury, namely the fracture of the right scaphoid and surgery following the fracture, contributed to the impairment assessed by the Medical Assessor.
4. The Appeal Panel accepts that Mr Sawyer was asymptomatic when he commenced employment with the respondent. However, the MRI scan shows advanced osteoarthritis which would have been caused, in part, by the fracture of the scaphoid and subsequent surgery. The Appeal Panel is satisfied that the restricted movement is due to osteoarthritis and arthroplasty and a deduction should be made in respect of that part of the assessment, that is restriction of movement and arthroplasty. The Appeal, Panel is not satisfied that the pre-existing condition contributed or caused part of the impairment assessed for sensory loss.
5. The Appeal Panel considers that the deduction for the pre-existing condition will be difficult to determine because there is no radiological evidence available in relation to the right wrist and hand before the work injury. The Appeal Panel therefore considers that a deduction should be applied under s 323(2) and that the deduction of 10% is not at odds with the evidence.
6. The Appeal Panel therefore calculated impairment as follows:

9% UEI was assessed for thumb CMC implant arthroplasty per AMA 5 p506 Fig 16.27.

8% UEI was assessed for restricted ROM of the thumb per AMA 5 p456 fig 16.12, p 457 fig 16.15, p 459 tab16.8 a&b and p 460 tab 16.9.

11% UEI was assessed for restricted ROM of the wrist per AMA 5 p 467 fig16.28 and 469 fig 16.31.

The previous scaphoid fracture has contributed to the development of STT arthritis. The extent of the deduction is difficult or costly to determine so in applying the provisions of s.323(2) the deductible proportion was assessed as one tenth.

10% UEI was assessed for persistent sensory deficit following carpal tunnel release per AMA 5 p 492 tab 16.5 and p 482 tab 16.10.

No deduction was applied for the carpal tunnel syndrome.

According to AMA 5 p 439 tab 16.3 this converts to 19% WPI.

1. Therefore, the Appeal Panel assesses 19% WPI of the right upper extremity.
2. For these reasons, the Appeal Panel has determined that the MAC issued on 28 April 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 Gregory McGroder and issues this new Medical Assessment Certificate as to the matters set out in the Table below:

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