WORKERS COMPENSATION - Workplace Injury Management and Workers Compensation Act 1998; review of Medical Assessment Certificate (MAC); whether the Medical Assessor (MA) ought to have assessed the appellant's impairment from the appellant's injury to his knees by reference to Table 17-31 of the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th ed (AMA 5), that is arthritis, rather than Table 17-33, that is a diagnosis based estimate; Held - MA did not err by assessing the appellant's impairment by reference to Table 17-33, and meticulously explained why he did so; the MA applied the correct criteria to assess the appellant's permanent impairment from his injury; MAC confirmed.

1. On 25 August 2025 Paul Workman, the appellant, lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Dr Todd Gothelf, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on 29 July 2025.
2. The appellant relies on the following grounds for 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 for 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. The appellant commenced employment around 1997 with the New South Wales Government within its Department of Education. The Secretary of the Department of Education, the respondent, is in accordance with s 26(1) and Part 1 of Schedule 1 of the Government Sector Employment Act 2013, the employer of the appellant.
2. The appellant worked as a school assistant. He eventually came to be placed at the Empire Bay Public School.
3. In a statement he signed on 27 May 2025 he described his work involved maintenance at the school and that is was physical and often involved frequent use of machinery, ladders and walking. He further described that during the school holiday break between December 2019 and January 2020 he was tasked to clear vegetation and do work involving ladders. He described that during this period he began to experience left knee pain that eventually worsened in March 2020, resulting in his consulting his general practitioner. An MRI scan was done of his knee that revealed a medial meniscal tear and a bone marrow oedema. In May 2020 he had an arthroscope during which a partial medial meniscectomy was done.
4. Whilst recovering from that procedure, he experienced right knee pain and on 14 September 2020 an MRI scan revealed he had a meniscal tear in that knee. On 11 November 2020 he had a partial medial meniscectomy done during arthroscopic surgery on that knee. A subsequent MRI revealed a recurrence of the medial meniscal tear in that knee and he underwent further arthroscopic surgery on 31 May 2021 to correct that.
5. A scan done in February 2024 revealed he had a displaced meniscal tear in his left knee. He had further arthroscopic surgery on that knee in March 2024.
6. On 13 December 2024 his solicitors wrote to the respondent's insurer notifying it that the appellant claimed compensation for permanent impairment resulting from an injury to his knees. They advised that the appellant relied on a report of orthopaedic surgeon Professor Youssef Ghabrial dated 4 December 2024, who had assessed the degree of the appellant's permanent impairment from the injury is 24% whole person impairment (WPI). They enclosed with their correspondence a copy of Professor Ghabrial's report wherein Professor Ghabrial advised that his assessment was a combination of 12% WPI for each knee, (which Professor Ghabrial assessed by reference to the criteria of Table 17-31 of AMA 5) and 1% for scarring. The Appeal Panel observes that Professor Ghabrial's reasoning for his assessment that the appellant has 12% WPI relating to each knee was set out in an earlier report he provided to the appellant's solicitor dated 29 November 2023, in which he stated "the latest x-rays of the knees performed in March 2023 suggested a 2mm cartilage interval in the medial compartment of each knee as well as the patellofemoral compartment of each knee, therefore the whole person impairment of each knee is assessed at 12%, according to Table 17-31".
7. By way of a notice the insurer issued on 26 May 2025 to the appellant pursuant to s78 of the 1998 Act, the insurer advised the appellant it did "not believe that you are eligible for permanent impairment lump sum compensation because your accepted physical injury has not resulted in more than 10% permanent impairment as required by s66(1) of the Workers Compensation Act 1987". It relied on a report it obtained from orthopaedic surgeon Dr Robin Diebold dated 26 March 2025 who had examined the appellant on that day and who in his report advised he assessed the degree of the appellant's permanent impairment from the injury to his knees is 7% WPI. That assessment was based on Dr Diebold finding that the appellant had cartilage reduction in the medial compartment in each of his knees to 3mm which in accordance with Table 17-31 of AMA 5 equated to 3% WPI for each knee, but from which Dr Diebold made a deduction of a half for constitutional arthritis reducing that to 2% WPI for each knee. Dr Diebold also combined that assessment with 1% WPI for a partial medial meniscectomy in each knee, in accordance with Table 17-33 of AMA 5, which meant that Dr Diebold's assessment for the permanent impairment he considered the appellant had relating to each of his knees is 3% WPI. Dr Diebold also found that the appellant had 1% WPI relating to the scarring the appellant had. All those assessments combined to 7% WPI.
8. Following the respondent's insurer's refusal to accept his claim, the appellant commenced proceedings in the Personal Injury Commission (Commission), seeking the Commission determine his claim for compensation. A delegate of the President of the Commission issued on 18 June 2025 a referral of the medical dispute to the Medical Assessor. In the MAC the Medical Assessor issued on 29 July 2025 he certified he assessed the degree of the appellant's permanent impairment from his injury is 2% WPI, being a combination of 1% WPI relating to the right knee and 1% WPI relating to the left knee. He made his assessment by reference to the criteria of Table 17-33 of AMA 5.
9. Given the issues that have been raised by the appellant in his appeal against the medical assessment, it is appropriate, in the Appeal Panel's view, to set out verbatim the reasons the Medical Assessor provided in the MAC for his assessment, but absent images of x-ray films he included within the explanation he provided (those not being included simply because they cannot be copied across into this document).

"Impairment is to be determined using the NSW Worker's Compensation Guidelines for the evaluation of permanent impairment, Fourth edition, 1 March 2021 (the Guides), and the AMA Guides to Evaluation of Permanent Impairment 5th Edition (AMA 5).

The right knee had a medial meniscal tear on MRI, and two arthroscopies were performed for a partial medial meniscectomy.

ROM- Table 17-10 p 537 AMA5 is used. The measured active range of motion was within normal limits and did not attract any rateable impairment.

DBE- Table 17-33 p 546 AMA5 is considered. There was a medial partial meniscectomy performed in both surgeries. A partial meniscectomy results in a 2% LEI or 1% WPI.

Arthritis- Table 17-31 p 544 AMA5 is considered. I have listed the x-rays which Mr Workman brought in for review form 10 February 2022 and from 10 March 2023. As per section 3.20 p 16 the Guides, impairment can only be assessed according to the radiologically determined cartilage loss intervals shown in AMA5 table 17-31 p 544. When assessing the impairment of the knee joint, which is three compartments, only the compartment with the most impairment is used in the assessment. Measured impairments of different compartments cannot be combined.

As per page 17, the best view for the knee is usually an erect intercondylar projection. The ideal x-ray is a posteroanterior view, with patient standing and knees slightly flexed, or the Rosenberg view.

The Guides states that it should be recognised that joint space narrowing in the knee does not necessarily equate with articular cartilage loss as deficiency or displacement of the menisci can also have this effect. This may be applicable in the case of Paul Workman, as the findings at the left knee arthroscopy May 2020 revealed only grade 1 cartilage changes.

At the assessment I was able to measure directly on x-rays the cartilage intervals. The Rosenberg view from 10 February 2022 measured a 4mm interval on the left and right medial tibiofemoral compartments, and 6mm on the lateral tibiofemoral compartments, and 6 mm on the patellofemoral interval. The erect films from 10 March 2023 measured 6mm cartilage intervals in all compartments.

In accordance with the Guides, referring to Table 17-31, while there may be a slight decrease in the medial tibiofemoral compartment, these values translate to no impairment or 0% WPI.

The diagnosis-based estimates method is the only method that resulted in impairment, which results in a 2% LEI or 1% WPI.

There was no evidence of a pre-existing condition and therefore no deductions were applicable.

The left knee diagnosis was a medial meniscal tear. Surgery was performed on two occasions May 2020 and 23 March 2024 for a medial partial meniscectomy.

ROM- Table 17-10 p 537 AMA5 is used. The measured active range of motion was within normal limits and did not attract any rateable impairment.

At the assessment, as with the right knee I was able to measure directly on x-rays the cartilage intervals. The Rosenberg view from 10 February 2022 measured a 4mm interval on the left and right medial tibiofemoral compartments, and 6mm on the lateral tibiofemoral compartments, and 6 mm on the patellofemoral interval. The erect films from 10 March 2023 measured 6mm cartilage intervals in all compartments.

In accordance with the Guides, referring to Table 17-31, while there may be a slight decrease in the medial tibiofemoral compartment, these values translate to no impairment or 0% WPI.

The diagnosis-based estimates method is the only method that resulted in impairment, which results in a 2% LEI or 1% WPI.

There was no evidence of a pre-existing condition and therefore no deductions were applicable.

A referral was not made for skin. However, the injuries resulted in surgeries to both knees. Therefore, Scarring was assessed for completeness.

Table 14.1 p 74 the Guides is used. There were small portal incisions for both knees, well healed, good colour match, no widening, no trophic changes, no contour defect. Mr Workman was not conscious of the scars, and they were difficult to locate. In accordance with section 14.6 p 73 the Guides, a 0% WPI applies.

c. My brief comments regarding the other medical opinions and findings submitted by the parties and, where applicable, the reasons why my opinion differs I have reviewed the reports of Dr YAE Ghabrial dated 29 November 2023 and 4 December 2024

• Dr Ghabrial assessed impairment using the arthritis method using X-rays from March 2023 and noted measuring of a 2mm interval in the medial and patellofemoral compartments. I note that Dr Diebold observed the same x-rays and noted no loss of cartilage in the patellofemoral joint, and a 5mm interval of the medial compartment. I was able to assess the same x-rays and measured a 6mm cartilage interval in all three compartments. I cannot explain the large variation in measurements. For further clarification I have included photographs of the x-rays I viewed on the day of assessment:

o In the above images, it can be grossly observed that the medial tibiofemoral space

is fairly similar to the lateral tibiofemoral compartment and well preserved, without

gross evidence of arthritis. I made measurements directly on the radiographs, with

o The following x-rays are from the 10 February 2022:

o These x-rays are "Rosenberg" views. I measured cartilage intervals directly on the

x-rays with a ruler, and there was a 4mm interval of the medial compartment and a

6mm cartilage interval on the lateral and patellofemoral compartments.

• Based upon the above evidence, I consider that a measurement of a 2mm cartilage

interval was inaccurate, or not in accordance with instructions from the Guides or AMA5. The method of measurement by Dr Ghabrial was not described in his report, and I can therefore not provide further comment on how these measurements varied from mine.

• The method of calculation for impairment by Dr Ghabrial was incorrect. Even using the measurement of 2mm, A 2mm interval of the knee results in an 8% WPI, and a 2mm interval of the patellofemoral joint results in a 4% WPI.

• Section 3.20 p 16 the Guides specifically states:

o When assessing impairment of the knee joint, which has three compartments, only

the compartment with the major impairment is used in the assessment. That is,

measured impairments in the different compartments cannot be added or

o Applying this rule, either 8% WPI or 4% can be used, and usually the greater

amount is used, or 8% WPI. These impairment values are not to be combined.

I have reviewed the report of Dr Diebold dated 26 March 2025 and make the following comments:

• Dr Diebold used the arthritis method and indicated that the medial compartment joint

space was 5mm. Dr Diebold indicated that the x-rays were a larger sizing than

recommended in the AMA 5. He therefore proceeded to make allowances for the

differences by comparing his measurement of 7mm to the "normal" considered space of 4mm. He then indicated that the medial compartment in the left knee was compared to an equivalent of 3mm on the table. His calculations were not fully explained, but I imagine he reduced his measurements by some ratio from 5mm to 3mm. I consider that his approach is somewhat reasonable. However, it should be noted that this approach is not a standard form of calculation that is accepted in the Guides. In addition, there was no indication I could find on the x-rays provided that they were enlarged. Further, the table 17-31 discussed joint space loss with 4mm. However, it is also true that the joint interval may be larger than 4mm and normal, such as 6mm or 7mm. Therefore, I am not in full agreement with the method that one may assume that 7mm should be equivalent to 4mm, and therefore all measurements can be decreased by a multiplier.

• I am satisfied with my measurements and conclusions for the following reasons:

o There were no gross signs of arthritis in the knees. There were no osteophytes, no

o Mr Workman had two surgeries in both knees for partial medial meniscectomy. I

note the caution in the guides, which states that it should be recognised that joint

space narrowing in the knee does not necessarily equate with articular cartilage

loss as deficiency or displacement of the menisci can also have this effect. This

may be applicable in the case of Paul Workman, as the findings at the left knee

arthroscopy May 2020 revealed only grade 1 cartilage changes.

o The guides states that impairment can only be assessed according to the

radiologically determined cartilage loss intervals shown in AMA5 Table 17-31 (p

544). In all cases, the intervals measured were within normal limits.

• Thus, while Dr Diebold may conclude there was cartilage loss, in my opinion the

measurements do not relate to the impairment caused by the workplace injury. The

workplace injury was a medial meniscal tear and resulted in two surgeries in each knee for a partial medial meniscectomy. My assessment of the cartilage intervals indicated there was no significant loss of cartilage relating to arthritis, and my use of this method did not result in any rateable impairment. An assessment of impairment using the diagnosis based estimates method for partial meniscectomy is in my opinion a more accurate reflection of the impairment caused by the injury."

1. The Appeal Panel notes that the Medical Assessor detailed in the MAC his findings from his examination of the appellant's knees. No issue has been raised in the appeal regarding the thoroughness of the Medical Assessor's examination of the appellant or his findings based on his examination.

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. This is because the Appeal Panel came to the view that the appellant had not established either of the grounds for appeal on which he relied, and consequently the Appeal Panel had no reason or power to examine the appellant.[1]

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. Both parties made written submissions. They are not repeated in full, but have been considered by the Appeal Panel.
2. In summary, the appellant submitted that the Medical Assessor assessed his impairment by reference to the wrong methodology and ought to have assessed his impairment by reference to arthritis, as Professor Ghabrial and Dr Diebold had done. The appellant submitted to the effect that the Medical Assessor considered that the "actual date" of his injury is 12 March 2020, whereas his injury occurred as a consequence of the tasks he did in his employment over the course of time and was "deemed" to have occurred on 12 March 2020, rather than having actually occurred on that date. The appellant further submitted that the Medical Assessor "attributed impairment to a pre-existing condition without adequate justification or supporting evidence".
3. The Appeal Panel notes that the appellant made submissions regarding the Commission exercising a power of reconsideration. Those submissions do not relate to the task that the Appeal Panel must undertake. It is unclear to the Appeal Panel what the relevance of those submissions are with respect to its task of determining the appellant's appeal. On the Appeal Panel's analysis of them, no issue is raised by the appellant that relates to the grounds for appeal on which he relies to support his appeal against the medical assessment.
4. In reply, the respondent submitted that the Medical Assessor was correct to use diagnoses based estimates, specifically the criteria of Table 17-31, as the method by which to assess the appellant's degree of permanent impairment. The respondent submitted the Medical Assessor explained why he could not use arthritis as the method by which to assess the degree of the appellant's permanent impairment. The respondent submitted the Medical Assessor's explanation is based on a comprehensive history that is consistent with the medical evidence.

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.
3. The Appeal Panel does not accept the appellant's submission at the first listed [20][2] of his written submission to the effect that the Medical Assessor attributed the appellant's impairment to a pre-existing condition. The Medical Assessor clearly stated in the MAC that there was no evidence of a pre-existing condition. The Medical Assessor also clearly articulated that the appellant did not suffer from any relevant previous injuries or pre-existing conditions or abnormalities. Consequently, the Medical Assessor did not, and could not give his finding that the appellant did not have a pre-existing condition, make a deduction under s323(1) of the 1998 Act for any proportion of the appellant's impairment that is due to a non-existent pre-existing condition.
4. The Appeal Panel also rejects the appellant's submission within the first listed [18] that the Medical Assessor did not have regard to the correct nature of the appellant's injury, in that the Medical Assessor approached the assessment on the basis that the appellant suffered an injury on 12 March 2020, rather than suffering an injury that had occurred over time due to the tasks the appellant performed and that was deemed to have occurred on 12 March 2020. The Appeal Panel notes that s15 of the Workers Compensation Act 1987 fixes the date upon which the latter style of injury occurs.
5. The Appeal Panel considers that when the MAC is read as a whole the Medical Assessor was cognisant of the fact that the appellant's injury arose from the tasks that the appellant performed in his employment over a course of time. But even if that is not the case, and the Medical Assessor considered the appellant's injury occurred in a frank incident on 12 March 2020, such an error on the Medical Assessor's part, which the Appel Panel hastens to add it is not finding that the Medical Assessor made but is dealing with this as a hypothetical, would not affect the outcome in this matter. This is simply because the Medical Assessor found that the appellant did not have a pre-existing condition and consequently did not make a deduction under s323(1) of the 1998 Act. Hence, if it was the case that the appellant's injury had occurred on a specific date (which to repeat for the sake of clarity, is not the case but is being discussed as a hypothetical), the result is the same based on what the actual case in this matter is, being the appellant's injury occurred over a period of time.
6. The Appeal Panel also rejects the appellant's submission that the Medical Assessor based his assessment on incorrect criteria by not assessing the appellant's impairment by reference to Table 17-31 of AMA 5.
7. Paragraph 3.2 of the Guidelines requires a Medical Assessor to use a method of assessment that most specifically addresses the impairment with which a worker presents.
8. Paragraph 3.20 notes that the presence of arthritis is defined as cartilage loss which is measured by properly aligned plane x-ray or direct vision. That paragraph instructs that impairment can only be assessed according to radiologically determined cartilage loss intervals detailed in Table 17-31 of AMA5. The paragraph notes that the impairments due to cartilage loss in the various compartments of the knee cannot be added or combined and that a worker's impairment due to cartilage loss, or arthritis, is based on the compartment with the major impairment.
9. Paragraph 3.22 of the Guidelines instructs that a diagnosis of cartilage loss based on plain radiography should be cautiously made if secondary features of arthritis are lacking. Paragraph 3.23 instructs that accurate radiographic assessment of joints requires at least two views. Further, with respect to assessing the knee, the best view to determine cartilage loss is noted as being the erect intercondylar projection for the tibia femoral joint in the Rosenberg view. With respect to the patella femoral joint, the assessment should be made by reference to the Skyline view.
10. In the Appeal Panel's view the Medical Assessor has meticulously explained in the MAC why it is that he could not assess the appellant's impairment by reference to arthritis, that is cartilage loss. This is simply because the films of the x-rays of the appellant's knees did not reveal any cartilage loss, and hence did not reveal the appellant had any impairment due to arthritis. The films of the tibia femoral joint were weight bearing in the Rosenberg view and the films of the patella femoral joint were in the Skyline view, and hence these enabled the Medical Assessor to measure the cartilage intervals in the appellant's knees.
11. The Medical Assessor identified that the two other methods of assessment, based on the appellant's presentation and clinical history, that could be used to rate the appellant's impairment were the range of movement the appellant had of his knees, which was normal and would not yield assessment of impairment, or a diagnostic based estimate, which in accordance with Table 17-33 of AMA 5 allowed a rating of 1% WPI for each knee of the appellant on the basis that he had a partial medial meniscectomy. The Medical Assessor correctly adopted the latter method.
12. In short, the Medical Assessor provided a thorough and meticulous explanation for his assessment of the appellant's permanent impairment and he applied the correct criteria to assess the appellant's impairment and again provided a considered and meticulous explanation for using the methods he did.
13. For these reasons, the Appeal Panel has determined that the MAC issued on 29 July 2025 should be confirmed.

[1] New South Wales Police Force v Registrar of the Workers Compensation Commission of New South Wales [2013] NSWSC 1792 at [33]; Finnegan v Komatsu Forklift Australia Pty Ltd [2023] NSWSC 38 at [125]- [130].

[2] The Appeal Panel notes that the sequencing used in the appellant's submissions has been duplicated in some parts. That is, there is a series of submissions from [1] - [21] and then a further series of submissions that repeat the numbering [17]-[21. That sequencing continues onto [30].