Transport for NSW v Pettit - [2022] NSWPICMP 22

DETERMINATION OF APPEAL PANEL
CITATION:	Transport for NSW v Pettit [2022] NSWPICMP 22
APPELLANT:	Transport for NSW
RESPONDENT:	Colin Marshall Pettit
APPEAL PANEL:	Member Mr William Dalley Dr Mark Burns Dr John Ashwell
DATE OF DECISION:	16 February 2022
CATCHWORDS:	WORKERS COMPENSATION- Appeals in respect of assessment of whole person impairment (WPI) for two separate injuries; in assessing the lumbar spine, the parties agreed that the components of the assessment, DRE category, and Table 4.2 components added together totalled 26% WPI when Medical Assessor (MA) had incorrectly calculated 27% WPI; Held - error clearly established but parties’ agreement was not in accordance with paragraph 4.37 of the WorkCover Medical Assessment Guidelines 2006 which required resort to the Combined Values Chart when combining DRE and interference with ADLs with Table 4.2 modifiers; Robbie v Strasburger Enterprises Pty Ltd t/as Quix Food Stores & Ors applied to give 25% WPI; the appellant employer submitted in respect of injury to the right knee that the MA had failed to assess a deduction pursuant to section 323 of the Workplace Injury Management and Workers Compensation Act 1998 when that course was contrary to the weight of the evidence; an earlier assessment by an Approved Medical Specialist in 2011 had assessed a deduction of 2/5 in respect of pre-existing osteoarthritis; there was evidence of pre-existing osteoarthritis at the date of injury and the evidence required the MA to consider whether any part of the impairment resulted from that condition; the MA had not disclosed his reasons for making no deduction and error was established; a deduction of one-tenth was assessed and applied.

STATEMENT OF REASONS FOR DECISION OF THE APPEAL PANEL IN RELATION TO A MEDICAL DISPUTE

BACKGROUND TO THE APPLICATION TO APPEAL

On 16 July 2021 Transport for NSW, the appellant, lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Dr Jonathon Negus, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on 22 June 2021.
The appellant relies on the following grounds of appeal under section 327(3) of the Workplace Injury Management and Workers Compensation Act 1998 (1998 Act):
· the assessment was made on the basis of incorrect criteria,
· the MAC contains a demonstrable error.
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 grounds of appeal on which the appeal is made.
The WorkCover Medical Assessment Guidelines 2006 set out the practice and procedure in relation to the medical appeal process under section 328 of the 1998 Act. An Appeal Panel determines its own procedures in accordance with the WorkCover Medical Assessment Guidelines 2006.
The assessment of permanent impairment is conducted in accordance with the NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment, 4^th ed 1 March 2022 (the Guidelines) and the American Medical Association Guides to the Evaluation of Permanent Impairment, 5^th ed (AMA 5).

RELEVANT FACTUAL BACKGROUND

The respondent to this appeal, Colin Marshall Pettit, suffered injuries to his lumbar spine and right knee in the course of his employment as a transit officer with Transport NSW (formerly Rail Corp). The injury to the lumbar spine occurred on 8 August 2003 when Mr Pettit was lifting a heavy bag down from an overhead storage area and the injury to the right knee occurred on 25 May 2005 when he fell while pursuing an offender.
On 26 June 2006 Mr Pettit was examined by an orthopaedic surgeon, Dr James Powell, at the request of the workers compensation insurer with respect to injuries to the right knee and an injured left foot. At that time Dr Powell felt that a clear diagnosis of the right knee could not be made. He noted early osteoarthritis but felt that a medial meniscal tear was the most likely cause of symptoms at that time. This, he felt, was attributable to the subject injury.
Mr Pettit continued to have symptoms in both the lumbar spine and the right knee. On 4 August 2006 he underwent partial medial meniscectomy and a second procedure was performed for further partial medial meniscectomy on 9 February 2007. In July 2011 he underwent a right partial knee replacement.
In February 2011 Mr Pettit was examined by an Approved Medical Specialist (AMS) following referral of a medical dispute by the Registrar of the Workers Compensation Commission in respect of the extent of impairment in the right lower extremity as a result of injury to the right knee on 23 March 2005. The AMS assessed Mr Pettit as having 20% whole person impairment (WPI) in respect of the right lower extremity. The AMS assessed two-fifths of that impairment as due to a pre-existing osteoarthritic condition in the right knee.
Mr Pettit also continued to have back pain and on 18 February 2019 he underwent anterior interbody spinal fusion at L4/5 and L5/S1.
Mr Pettit also suffered an injury to his left knee in March 2011 in the course of his employment which ultimately resulted in a left total knee replacement in 2017. That injury did not form part of the claim in the present proceedings.
On 28 July 2017 Mr Pettit underwent a revision right knee procedure with total knee replacement. He subsequently developed an infection the right knee and had to be readmitted to hospital for intravenous antibiotics as well as manipulation of the knee followed by further oral antibiotics.
On 8 August 2018 Mr Pettit was examined by an orthopaedic surgeon, Professor Ghabrial, at the request of Mr Pettit’s solicitors. Professor Ghabrial diagnosed Mr Pettit as suffering L4/5 and L5/S1 disc protrusion with potential irritation of the neural elements on the left side as a result of workplace injury. He diagnosed post-traumatic osteoarthritic changes in both knees with bilateral total knee replacement. Noted that Mr Pettit had suffered post-operative infection in respect of the right knee. Professor Ghabrial assessed Mr Pettit as having 20% WPI as a result of injury to the right knee and 8% WPI in respect of the lumbar spine.
Mr Pettit was again examined by Dr Powell on 16 October 2018. Dr Powell noted the injury to the lumbar spine in 2003 as well as the injuries to the left and right knees. Dr Powell reported at that time that; “current pathology in the lumbar spine is principally the result of the initial trauma and so he is suffering from the effects of the work injury incident 2003”.
Professor Ghabrial examined Mr Pettit again on 6 July 2020. He noted that Mr Pettit had undergone anterior interbody fusion at the L4/5 and L5/S1 segments in February 2019 and further arthroscopic surgery in respect of the left knee in August 2019. On that occasion Professor Ghabrial assessed Mr Pettit as having 20% WPI respect of the right knee (fair result of right total knee replacement) and 23% WPI in respect of the lumbar spine (comprised of 20% WPI in respect of assessment as DRE IV and 3% WPI in respect of interference of activities of daily living).
Professor Ghabrial made no deduction from either assessment in respect of any previous injury or pre-existing condition or abnormality pursuant to section 323 of the 1998 Act.
On the basis of Professor Ghabrial’s assessment Mr Pettit’s legal representatives made a claim for lump-sum compensation in respect of the injury to the lumbar spine on 8 August 2003 and a further claim in respect of the injury to the right knee on 25 May 2005.
Mr Pettit was again examined by Dr Powell on 27 October 2020. Dr Powell noted the history of injury and treatment as well as the radiological evidence. Dr Powell assessed Mr Pettit as having achieved a good result respect of the right knee replacement and assessed 15% WPI as a result of injury to the right knee.
Dr Powell felt that 40% of that assessment was attributable to the pre-existing osteoarthritis and assessed Mr Pettit as suffering 9% WPI in respect of the right lower limb as a result of the subject injury. He attributed the impairment to workplace activities rather than to the specific incident in March 2005. Dr Powell was of the opinion that the condition in the lumbar spine represented the progression of a degenerative lumbar disease.
An Application to Resolve a Dispute, claiming lump-sum compensation in respect of the lumbar spine and further lump-sum compensation in respect of the right lower extremity, was filed in the Personal Injury Commission (Commission). The medical dispute in respect of those claims was referred to the Medical Assessor who examined Mr Pettit on 28 April 2021.
The Medical Assessor noted the history of injury, the course of treatment and the radiological evidence. He conducted a physical examination of the lumbar spine and the right knee. The Medical Assessor assessed Mr Pettit as having achieved a poor result from the right total knee replacement and accordingly assessed him as having 30% WPI in respect of the right lower extremity and as having 27% WPI in respect of the injury to the lumbar spine.
The Medical Assessor made no deduction pursuant to section 323 of the 1998 Act in respect of any pre-existing condition or abnormality or previous injury.

PRELIMINARY REVIEW

The Appeal Panel conducted a preliminary review of the original medical assessment in the absence of the parties and in accordance with the WorkCover Medical Assessment Guidelines 2006.
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 sufficient information is available to the Panel to enable the panel to determine the appeal.

EVIDENCE

Documentary evidence

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.

Medical Assessment Certificate

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.

SUBMISSIONS

Both parties made written submissions. They are not repeated in full, but have been considered by the Appeal Panel.
In summary, the appellant submits that the Medical Assessor erred in his assessment of the lumbar spine. It appeared from the MAC that the Medical Assessor had incorrectly assessed an additional 2% pursuant to Table 4.2 of the Guidelines in respect of “second and further levels” of surgery when only one additional level had undergone surgery.
In reply, the respondent did not dispute that the fusion surgery was performed at only two levels and that the appropriate allowance was 1% for a single additional level.
The appellant submitted, in respect of the right lower extremity, that the Medical Assessor had failed to appropriately consider section 323 of the 1998 Act or, in the alternative, had made no deduction pursuant to section 323 when that assessment was contrary to the evidence and therefore not available to the Medical Assessor.
In reply the respondent submitted that there was no evidence of a pre-existing condition which contributed to the level of impairment assessed at the time of examination. It was open to the Medical Assessor to assess Mr Pettit as having no previous condition or abnormality or any previous injury. The Approved Medical Specialist who had assessed Mr Pettit in 2011 had fallen into error in his application of section 323 of the 1998 Act.

FINDINGS AND REASONS

The procedures on appeal are contained in section 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.
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.

Lumbar spine

The Medical Assessor stated that he had assessed the lumbar spine as follows:
“DRE IV   20% WPI
ADL’s   2% WPI
Modifiers for DRE following surgery;
Residual symptoms – Lumbar 3% WPI
Second and further levels – Lumbar  1% each level”
The Medical Assessor then stated:
“20 + 2 (ADL’s) COMBINE 3 COMBINE 2 COMBINE 1 – 27%”
As the respondent noted in his submissions, the mathematical addition of the figures
20 + 2 +3 + 2 + 1 gives a total of 28 and not 27 as recorded by the Medical Assessor. The Panel accepts that this is evident.
Although it is clear that a mistake has been made, it is not altogether clear that the error arises from awarding an inappropriate additional 1% in respect of additional levels of surgery, but rather that the Medical Assessor has duplicated the assessment of 2% WPI for activities of daily living. If this were not the case, the inclusion of the “1” in the algorithm set out by the Medical Assessor would not relate to any particular item.
The respondent, in his submissions stated:
“The respondent does not dispute that the fusion surgery was performed at two levels, being 4/5 and L5/S1. He also does not dispute that, pursuant to Table 4.2, the appropriate allowance is 1% for one second or further level. The respondent also does not dispute that, when the assessment of 22%, 3% and 1% are combined, resulting impairment is 26%.”
The Panel accepts that the calculation of impairment in respect of the lumbar spine is affected by demonstrable error. The parties agree that the components identified by the Medical Assessor (DRE Lumbar IV – 20% + ADL’s – 2% + spinal surgery with residual symptoms and radiculopathy – 3% + additional level surgery – 1%) total 26%. That, however, is not the method of assessment required by the Guidelines[1]. In Robbie v Strasburger Enterprises Pty Ltd t/as Quix Food Stores & Ors[2], Adams J noted that the Guidelines in paragraph 4.37, following Table 4.2, provide for the calculation of WPI in respect of spinal injuries:
“HOW IS WHOLE PERSON IMPAIRMENT (WPI) FOR THE SPINE CALCULATED WHEN MODIFIERS APPLIED FROM TABLE 4.2?
The WPI from Table 4.2 is calculated separately and then combined with the DRE:
1.      Select the appropriate DRE category from Table 15-3, 15-4, or 15-5.
2.      Determine an impairment value within the allowed range in Table 15-3, 15-4,
15-5 according to the impact on the worker’s ADLs.
3.      Combine this value with the appropriate amount from Table 4.2 to determine the final whole person impairment, i.e. modifiers from Table 4.2 must be combined and the total amount from Table 4.2 combined with the total of the DRE category.”
[1] Chapter 4.37, page 29.
[2] [2017] NSWSC 363.
Adams J held that the correct approach, in accordance with the Guidelines, was to add the allowance for interference of activities of daily living to the DRE IV impairment. In the present case, this would yield 22% WPI (20% +2% = 22%). The additional allowances under Table 4.2 are then aggregated. In the present case there is an allowance of 3% in respect of “spinal surgery with residual symptoms and radiculopathy” and 1% for a second level of surgery giving a total of 4%.
The final step is to combine the two totals, 22% and 4%. This is done by reference to the Combined Values Chart[3], giving a combined value of 25%. Accordingly, Mr Pettit is assessed as having 25% WPI in respect of injury to the lumbar spine.
[3] AMA 5, page 604.

Right lower extremity – section 323 deduction

The Medical Assessor reported in the MAC that there was no proportion of loss of efficient use or impairment or whole person impairment, due to a previous injury, pre-existing condition or abnormality[4]. At paragraph 11 of the MAC the Medical Assessor had stated “there is no deductible proportion” in respect of the right lower extremity.
[4] MAC, paragraph 8e.
The appellant submits that there was evidence before the Medical Assessor which suggested that there was a pre-existing condition in the right knee which raised the issue of whether a deduction should be made pursuant to section 323 of the 1998 Act. The Medical Assessor, it was submitted, had failed to address that evidence or to provide reasons for making no deduction.
The appellant noted the radiological evidence of osteoarthritis which predated the injury to the right knee on 23 March 2005. That evidence was noted by Dr Powell in his report dated 27 June 2006, and by the AMS who had assessed Mr Pettit’s right knee in 2011. The AMS had deducted two-fifths of the total impairment in respect of a pre-existing condition.
The respondent in his submissions noted the nature of the pathology caused by the injury which occurred on 23 March 2005 and the findings on arthroscopic examination in August 2006. The respondent noted that:
“a large posterior horn medial meniscal tear was debrided and approximately 50% of the meniscus was removed to a stable rim. This left a small posterior rim present. A second arthroscopy was performed on 9 February 2007 following which only 20% of the meniscus remained which really was a residual rim posteriorly medially and materially[5]”.
[5] MAC dated 10 February 2011 by AMS Dr Kim Ostinga, page 53 of the Application to Resolve a Dispute at page 54.
The respondent noted that the Medical Assessor had reported:
“He suffered an injury to the right knee which damaged his meniscus. following two surgeries for partial meniscectomy, in a virus knee, this led to accelerated post-traumatic arthritis and subsequent replacement surgery.”
The respondent submitted that the reasoning of the Medical Assessor was correct and not challenged on appeal.
The Panel accepts that the Medical Assessor had before him the radiological evidence of pre-existing osteoarthritis in the right knee prior to the injury on 23 March 2005. The Medical Assessor also had the earlier MAC, dated 10 February 2011 in which the AMS had set out his reasons for deducting 40% of the impairment as due to pre-existing condition. Dr Powell in his earlier reports had also referred to the presence of osteoarthritis. Dr Powell had reported: “X-Ray showed early degenerative changes in the medial compartment and early patellofemoral arthrosis”. He reported “There is early osteoarthritis is which is unlikely to be a major contributing factor to Mr Pettit’s current symptoms” and “Early osteoarthritis changes were found on x-ray and examination but are not major contributors to the current symptoms.” Dr Powell, however regarded the presence of osteoarthritis as justifying a deduction of two-fifths when he reported to the insurer in 2020.
Section 323 of the 1998 Act relevantly 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.
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 Workers Compensation Guidelines may make provision for or with respect to the determination of the deduction required by this section.
Note : Section 68B of the 1987 Act makes provision for how this section applies for the purpose of calculating workers compensation lump sum benefits for permanent impairment and associated pain and suffering in cases to which section 15, 16, 17 or 22 of the 1987 Act applies.”

The Medical Assessor noted that the MRI scan performed on the right knee on 12 January 2007 had shown medial compartment osteoarthritis. He reported “He suffered a post-traumatic osteoarthritis of the knee leading to arthroscopic partial meniscectomy and subsequent total knee replacement surgery.”
The Medical Assessor stated that, in making his assessment, he had taken into account:
“He suffered an injury to the right knee which damaged his meniscus, following 2 surgeries for partial meniscectomy, in a varus knee, this led to accelerated post-traumatic arthritis and the subsequent replacement surgery.
He has radiology of both his lumbar spine and knees that demonstrate no significant pre-existing injury or condition prior to his stated injuries. Therefore in my opinion, there is no deduction for pre-existing conditions.”
The Panel accepts that there was evidence before the Medical Assessor including the reports of X-ray investigation closely following on the accident involving the right knee in March 2005 which established the presence of a pre-existing condition in the right knee. The report of the X-ray of both knees dated for May 2005 noted:
“Clinical details: osteoarthritis both knees.
Findings: there is a little loss of joint space noted in both knees within the medial compartment. Minor marginal osteophytes basis is noted. Also some minor sharpening of the inter-condylar evidences. No loose body. No other significant focal bony abnormality”.
The Medical Assessor did not regard the existence of osteoarthritis in the right knee as a “significant pre-existing injury or condition”. However, it is clear that there was evidence of a pre-existing condition and section 323 required the Medical Assessor to consider whether this contributed to the overall level of impairment assessed upon examination[6].
[6] Cole v Wenaline Pty Ltd [2010] NSWSC 78.
The appellant noted that Dr Powell in his report dated 22 December 2020 had assessed a deduction of 40% pursuant to section 323. Dr Powell reported: “Deduction for a pre-existing condition is assessed at 40% as he had well-established osteoarthrosis of the right knee with deformity identified on clinical assessment 12 months prior to the incident and confirmed on imaging close to the time of the incident.”
The “incident” referred to by Dr Powell is presumably the subject injury on 23 March 2005. Dr Powell in his report discusses the imaging available to him in respect of the right knee. He listed reports of X-rays of both knees performed on 21 January 2011 which were said to show “right knee osteoarthritic change showing joint space narrowing mainly in the medial compartment with osteophyte formation. Similar changes in the left knee less advanced. Bilateral genu varum.”
With respect to the other imaging, it appears that Dr Powell relied upon the reports noted by the AMS in the MAC of 10 February 2011, the earliest of which is an X-ray of the right knee performed on 4 May 2005, reported as showing “loss of medial joint space”. This was noticed to be present in both knees. The next report of imaging is that of the right knee MRI performed on 12 July 2006. The report disclosed “an oblique posterior horn tear of the medial meniscus with small osteochondral defect in the medial femoral condyle joint effusion and popliteal cyst.”
Although it is apparent from the MAC that the Medical Assessor described “post-traumatic osteoarthritis” in the right knee, it is evident from the radiological evidence that there was a pre-existing osteoarthritic condition in the right knee at the time of the subject injury, 23 March 2005. The Medical Assessor was therefore obliged to consider whether any part of the impairment assessed upon examination resulted from any previous injury or pre-existing condition or abnormality at that date.
The Panel accepts that the Medical Assessor fell into error in not considering whether the pre-existing condition contributed to the level of impairment assessed upon examination.
The Panel notes that the AMS in his MAC dated 10 February 2011 assessed two-fifths of the impairment assessed as attributable to the pre-existing osteoarthritic condition in the right knee. Dr Powell, in his report dated 22 December 2020, assessed a similar deduction.
The Panel does not accept the methodology adopted by the AMS in the earlier MAC. The AMS explained his methodology in assessing the extent of the deduction:
“Assessment of impairment is somewhat complicated by the fact that there is a constitutional predisposition to osteoarthritis which affects both knees symmetrically.
The excision of the meniscus on the right knee associated has accelerated the arthritic process considerably as would be expected.
An MRI has already indicated complete loss of articular cartilage on the right side of the knee. It is reasonable to suppose that the situation continues to exist. Therefore an assessment of impairment can be made on the grounds of complete loss of joint space on the right side.
Clearly a deductible contribution is indicated and the fairest way of assessing this would be to get standing x-rays of both knees and calculate the difference in joint spaces between the two. Then apply table 17-31.”
The “standing x-rays of both knees” were obtained and the AMS measured the cartilage loss on the medial side of the right knee and compared this with the X-rays of the left knee taken on 21 January 2011. He drew the conclusion from the comparison that there was a two-fifths deduction attributable to the pre-existing condition.
The Panel does not accept that this was an appropriate method for the assessment which was required to be performed pursuant to section 323 of the 1998 Act. To base an assessment of the extent of the deduction pursuant to section 323 of the 1998 Act by means of comparison of imaging of the left knee performed in January 2011 was not, in the opinion of the Panel, an appropriate method of assessing the extent to which the pre-existing condition in the right knee as at the date of injury contributed to the extent of impairment assessed at the time of examination.
Dr Powell based his deduction on the existence of “well-established osteoarthritis of the right knee with deformity identified on clinical assessment 12 months prior to the incident and confirmed on imaging close to the time of the incident.” The Panel could not identify the evidence of “clinical assessment 12 months prior to the incident” which occurred in March 2005. The earliest imaging relating to the condition in the right knee appears to be the X-ray report on 4 May 2005.
That X-ray report was considered in Dr Powell’s report in June 2006. Dr Powell said the
[7] Report, Reply page 257.
X-ray “showed early degenerative [changes] in the medial compartment and early patellofemoral arthrosis”. At that time Dr Powell’s opinion was “there is early osteoarthritis is which is unlikely to be a major contributing factor to Mr Pettit’s current symptoms” and “Early osteoarthritis changes were found on x-ray and examination but are not major contributors to the current symptoms.”[7]
The X-ray report in evidence[8] notes “osteoarthritis in both knees” and the findings are recorded: “There is a little loss of joint space noted in both knees within the medial compartment. Minor marginal osteophytosis is noted. Also some minor sharpening of the intercondylar eminences. No loose body. No other significant focal bony abnormality.”
[8] Reply, page 133
Dr Powell’s assessment in December 2020 may be based on the osteoarthritis present at the time of his examination, but it does not appear to reflect the situation at the date of injury. As noted by Dr Powell, the X-ray report dated for May 2005 suggests only minor degenerative changes and, as noted by the Medical Assessor and Professor Ghabrial, there has been a substantial degree of post-traumatic osteoarthritis since the date of injury and resulting from that injury.
The Panel has reviewed the limited evidence of the extent of the pre-existing condition in the right knee from the radiological reports and has noted the opinion of the Medical Assessor in the MAC and the reports of Professor Ghabrial and Dr Powell. The Panel is satisfied that there was a pre-existing osteoarthritic condition in the right knee. The Panel does not accept the opinion of Dr Powell as expressed in his report of December 2020 as to the extent of the deduction to be made, but is of the view that there was a minor contribution to the level of impairment assessed upon examination by the Medical Assessor.
The Panel accepts that it is difficult to assess the extent of that contribution but, having regard to the earlier opinion of Dr Powell expressed in his report from 2006 and the report of the 2005 X-ray, it is appropriate to assess the extent of that impairment as one-tenth.
No submissions have been addressed to the overall level of assessment of the right lower extremity and the assessment appears to have been carried out in accordance with the Guidelines. Accordingly, Mr Pettit is assessed as having 30% WPI in the left lower extremity. A deduction of one-tenth is appropriate pursuant to section 323 (2) of the 1998 Act in respect of pre-existing osteoarthritis giving 27% WPI in respect of impairment arising from the subject injury.
For these reasons, the Appeal Panel has determined that the MAC issued on 22 June 2021 should be revoked, and a new MAC should be issued. The new certificate is attached to this statement of reasons.

PERSONAL INJURY COMMISSION

APPEAL PANEL

MEDICAL ASSESSMENT CERTIFICATE

Injuries received after 1 January 2002

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 Dr Jonathon Negus 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 WorkCover Guides	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)
1. Lumbar spine	8/08/03	Chapter 4, paragraphs 4.17-4.35, 4.37, Table 4.2	Chapter 15, Table 15-3	25%	nil	25%
2. Right lower extremity (knee)	23/03/05	Chapter 3, substituted Table 17-35, page 21	Chapter 17, paragraph 17.2j, page545,	30%	1/10	27%
Total % WPI lumbar spine 8 August 2003					25%
Total % WPI right lower extremity 23 March 2005					27%

Mr William Dalley
Member
Dr Mark Burns

Medical Assessor

Br John Ashwell

Medical Assessor

16 February 2022