WORKERS COMPENSATION - Workplace Injury Management and Workers Compensation Act 1998; review of Medical Assessment Certificate (MAC); assessment of the right lower extremity; worker appealed; submitted that the Medical Assessor (MA) erred when he failed to make a deduction under section 323; Held - Appeal Panel found error and noted the MA's reasons were adequately explained and accorded with the available evidence; MAC confirmed.

1. On 13 June 2025 the employer, Macquarie University (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 16 May 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. 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. The appellant did not seek that the worker be re-examined by a Medical Assessor who was also a member of the Appeal Panel.
3. As a result of its preliminary review, the Appeal Panel determined that the worker was not required to undergo a further medical examination because the Appeal Panel, for the reasons set out below, did not find error. Absent a finding of error the Appeal panel has no power to require that the worker undergo a re-examination: see New South Wales Police Force v Registrar of the Personal Injury Commission of New South Wales [2013] NSWSC 1792.

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.

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 matter was referred by the Personal Injury Commission to the Medical Assessor as follows.

"The following matters have been referred for assessment (s 319 of the 1998 Act):

• Date of injury: 5 April 2011
• Body parts/systems referred: Right lower extremity, Left lower extremity,

• Method of assessment: Whole Person Impairment."

page and paragraph number in NSW workers compensation guidelines

Chapter, page, paragraph, figure and table numbers in AMA 5 Guides

WPI deductions pursuant to S323 for pre-existing injury, condition or abnormality (expressed as a fraction)

Sub-total/s % WPI (after any deductions in column 6)

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

1. The employer appealed.
2. The complaint on appeal only concerns the right lower extremity. The complaint on appeal does not concern the assessment for overall impairment of the right lower extremity (knee) but rather concerns the failure of the Medical Assessor to make a deduction under s 323 for any pre-existing condition abnormality or injury.
3. In summary, the appellant submitted on appeal that the Medical Assessor made an assessment on the basis of incorrect criteria and/or made demonstrable error for reasons which included the following:

(a) the Medical Assessor erred and applied incorrect criteria by failing to "apply or discuss the apparent pre-existing or external factors at all, despite reviewing the medical evidence indicating same" when deciding not to make a deduction under s 323;

(b) the Medical Assessor failed "to give any or any sufficient regard to the other relevant information before him";

(c) in describing the injury as an aggravation of a pre-existing osteoarthritis but not making a deduction for the pre-existing condition;

(d) the failure to make a deduction was at odds with the worker's statement evidence and which demonstrates he had prior symptoms in his knee (prior to the deemed date of 5 April 2011) and the Medical Assessor failed to have any regard or any adequate regard to this evidence, and

(e) it was open to the Medical Assessor to find that the numerous injuries to the right knee prior to the deemed date of injury of 5 April 2011 contributed directly to the assessed impairment.

1. In summary, the respondent worker Mr John William Robertson (the respondent) submitted that the Medical Assessor did not make an assessment on the basis of incorrect criteria and did not make demonstrable errors and that the MAC should be confirmed.
2. The role of the Medical Assessor is to conduct an independent assessment on the day of examination. The Medical Assessor is required to take a history, conduct an examination, make a diagnosis and have due regard to other evidence and other medical opinion that is before the Medical Assessor. The Medical Assessor must bring his clinical expertise to bear and exercise his clinical judgement when making an independent assessment of impairment and must apply the correct criteria for assessment under the Guidelines.
3. The path of reasoning disclosed by the Medical Assessor must be adequate. This is also dependent on the extent of the history taken and a thorough examination of the respondent so with an adequate record of examination findings so that it can readily be understood by the reader that the correct criteria under the Guidelines have been applies. The MAC must be read as a whole.
4. The Medical Assessor recorded the following history:

"● Brief history of the incident/onset of symptoms and of subsequent related events, including treatment:

Mr Robertson stated that she reported the injury 5 April 2011. Mr Robertson stated that during his work as a security guard from May 2001 and August 2013 at Macquarie University, he was exposed to heavy lifting, bending, twisting.

Mr Robertson reported injuries to his lumbar spine, right knee, left shoulder.

Mr Robertson stated that he started to notice pain in his knees over many years while employed at Macquarie University. He recalled seven separate injuries to his knees during his employment, but could not recall the exact details. He recalled initially injuring the left knee in 2004 with a twisting injury.

Mr Robertson suffered an injury to his right knee 23 December 2008, twisting the knee while at work while moving a file cabinet.

He recalled an injury 5 April 2011 while doing traffic control work and supervising one of the parking lots. He was bending down to take photographs to issue parking fines and hit a large tow bar on one of the vehicles with his left knee. He had immediate pain and sought treatment.

Mr Robertson had a further injury to his left knee 26 July 2011 when he suffered a twisting injury walking up a flight of stairs at work.

His right knee deteriorated, and a right knee replacement was recommended. Surgery was done on the right knee 3 December 2021. A left knee arthroscopy was recommended. He had a left knee arthroscopy 4 March 2022.

• Lumbar Spine L5/S1 fusion 28 June 2019.
• Lumbar Spine L3/4, L4/5, L5/S1 fusion 24 February 2020.
• Right total knee replacement 3 December 2021.
• Right knee manipulation 4 February 2022.
• Left knee arthroscopy 4 March 2022.
• Left shoulder arthroscopic rotator cuff repair and biceps tendon repair 17 June 2022.
• Present treatment:

Mr Robertson is no longer having treatments for his knees.

Mr Robertson rated the left knee pain as a seven on a scale of zero (no pain) to ten (the worst pain imaginable) and constant.

Mr Robertson rated the right knee pain as a ten out of ten and constant, at rest or with activities.

• Details of any previous or subsequent accidents, injuries or condition:

Mr Robertson recalled a right elbow injury 24 October 2005 as a work injury. Mr Robertson recalled a right leg and right knee work injury 23 December 2008.

Mr Robertson denied any problems with his knees prior to his employment in 2001.

Mr Robertson denied any major motor accidents resulting in injury.

Mr Robertson recalled that in August 2014 his right knee gave way causing him to fall. He stated that he did not slip or stumble, but his right knee gave way. He sustained a lumbar spine fracture at L4 and was put in a back brace.

Mr Robertson is a 65-year-old male in general good health. He has a past history of diabetes and high blood pressure. Mr Robertson takes medications for blood pressure and diabetes.

Mr Robertson denied smoking cigarettes and denied drinking alcohol regularly.

• Work history including previous work history if relevant:

Mr Robertson was employed by Macquarie University at the time of the subject injury 5 April 2011. His position was security guard, and the hours were full time, forty hours a week. He started working for this company in 2001. His daily tasks involved performing security of the buildings and the infrastructure of the property. He also directed traffic and parking of the students and staff. His duties also required him to perform furniture removal from time to time. He had to move students and staff from one location to another, moving offices for the staff.

Mr Robertson was made redundant in 2013 and was not capable of resuming any employment since then. Mr Robertson stated that the lower back was the worst injury.

Mr Robertson lives in a house with colleagues. Mr Robertson is able to shower and struggles bending over to put on shoes. He uses a walker outside of the house. He is unable to perform housework and does no sports or hobbies. He has not been able to play golf since 2002."

1. The Medical Assessor had regard to the special investigations as follows:

Mr Robertson provided verbal permission to view investigations online.

Moderate T5/6 disc extrusion with mild mass effect on the thoracic cord. Chronic T12 vertebral compression fracture on a background of Scheuermann's disease. L4/5 and L5/S1 end plate degeneration with moderate left L5 neural exit foramen stenosis.

**5 April 2011- X-rays Left Knee Central Cost Radiology. I viewed these, I measured no loss of cartilage and no arthritis.

Degenerative L5/S1 discs with a left paracentral disc protrusion with left sided lateral recess and foraminal narrowing and moderate canal stenosis at L4/5.

Distal quadriceps tendinopathy with a small intrasubstance partial thickness tear in the distal medial quadriceps tendon, peritendonitis and prepatellar bursitis.

Spinal degenerative changes. Compression fracture of L4. CT scan is advised to further assess the vertebra and to exclude any posterior bony displacement.

Some patellofemoral and chondral loss. Minimal degenerative change ACL. Some extensor mechanism spurring degeneration.

Minimal degenerative changes. No meniscal tear has been shown.

The knee prosthesis appears satisfactory position without visible complication. There is no evidence of a fracture.

A specific cause for the patient's symptoms has not been identified. No periprosthetic complication is identified related to indwelling right-sided total knee arthroplasty. Spurring at the medial aspect of the proximal tibia. Given sudden onset knee pain symptoms, if there are focal pain symptoms related to the medial aspect of the proximal left tibia, then a CT may be of benefit for further characterisation.

**11 April 2025- X-rays Left and Right Knees. Hunter Imaging. Right Total Knee Replacement. Left knee joint I measured well preserved spaces, no loss of cartilage."

1. The Medical Assessor conducted a physical examination and recorded his findings about which there is no complaint on appeal and the overall level of impairment assessed is not complained about on appeal.
2. The Medical Assessor summarised the injury and diagnosis as follows:

Mr Robertson is a 65-year-old male who sustained an injury at work 5 April 2011. As a result of the subject injury Mr Robertson has the following diagnoses:

• Left knee strain, aggravation of pre-existing left knee arthritis. An x-ray of the left knee 5 April 2011 revealed no loss of cartilage and no arthritis. Treatment was initially conservative. Surgery was performed 4 March 2022 for a left knee arthroscopy and chondroplasty. Mr Robertson reported persistent left knee pain. The physical examination revealed a normal active range of motion and stable knee.
• Right knee aggravation of pre-existing arthritis, consequential to the left knee due to favouring. X-rays May 2019 revealed minimal degenerative changes. An MRI of the right knee 8 May 2019 revealed patellofemoral chondral loss. Surgery was performed for a right knee replacement 3 December 2021. A further surgery was performed 4 February 2022 for a manipulation. Mr Robertson reported persistent pain.
• consistency of presentation

The history is consistent with the physical examination findings and is consistent with the documentation provided. The diagnosis of injuries is consistent with the mechanism of injury and is consistent with the current status of the condition."

1. The Medical Assessor explained his assessment of permanent impairment of right lower extremity based on a fair result for the knee replacement. There is no complaint on appeal about this assessment. The complaint only concerns the failure to make a deduction under

s 323. 2. The Medical Assessor gave the following reasons for making no deduction under s 323:

"● Deductions According to section 1.27 and 1.28, page 6 of the Guides, the degree of permanent impairment should not be included in the final calculation of permanent impairment if those impairments are not related to the compensable injury. 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 portion' 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.

When considering the deductible portion, the following factors were considered:

• The injury date of 5 April 2011, according to the referral, represents an injury due to the nature and conditions of Mr Robertsons employment. The history provided by Mr Robertson supported that there were multiple injuries to the right and left knees which led to the need for treatment. If it is the case the right and left knee injuries were 'disease' injuries, and that employment was the main contributing factor to these 'disease' injuries, then I have considered that any injury to both knees during his employment with Macquarie University are part of the injury, and are not considered pre-existing injuries.
• There was no evidence of a pre-existing injury or condition of both knees prior to his employment with Macquarie University.
• I have viewed x-rays brought in my Mr Robertson from 5 April 2011 of the left knee which revealed no loss of the cartilage intervals. There was therefore no evidence of an impairment on x-rays of the left knee prior to the workplace injury.
• X-rays from 8 May 2019 revealed minimal degenerative changes, according to the report. I therefore consider that it is highly unlikely that arthritis was present in both knees prior to Mr Robertson's employment start 2001.

Considering the above evidence, I consider that no deduction is warranted as there was no evidence of a pre-existing condition prior to Mr Robertson's employment from 2001."

1. The Medical Assessor explained where his opinion differed from other medical opinion as follows:

"I have reviewed the report of Dr Charles New dated 30 January 2024 and make the following comments:

• Dr New arrived at a similar impairment for the right knee of 20% for a fair result from the total knee replacement.
• Dr New applied a 3% impairment to the left knee for arthritis, referring to table 17-31, p 544. There was no explanation as to how a 3% was determined, but I expect this is by applying a 3mm interval. It is unclear how this was applied, as I did not see the x-rays that were referred to. In my review of x-rays at this assessment, the x-rays from 11 April 2025 were appropriate x-rays to measure cartilage intervals, and on the left knee these intervals were at least 4mm in all relevant aspects, which would result in a 0% impairment due to arthritis.
• Dr New applied a 3% WPI for scarring. It was unclear how this figure was arrived at. His physical findings indicated 'he has a scar consistent with total knee arthroplasty.' Without noting any other features, this description in my opinion would be in accordance with section 14.6 p 73 which states 'uncomplicated scars for standard surgical procedures do not, of themselves, rate in impairment.'

I have reviewed the reports of Dr Chris Harrington dated 13 August 2024, 18 October 2024, and 17 January 2025 and make the following comments:

• We arrived at a similar 'fair' result for the right knee and applied a 20% WPI.
• Dr Harrington indicated he made a 1/10th deduction, and then stated there was a 14% WPI for the right knee. The math seems incorrect, as a 10% deduction would result in an 18% WPI.
• I did not apply a deduction for reasons explained above in the calculation of WPI."

1. Dr New, the IME qualified to provide an opinion on behalf of the respondent worker made no deduction under s 323. Dr Harrington, the IME qualified to provide an opinion on behalf of the appellant made a one-tenth deduction. The Medical Assessor had to make an independent assessment as to whether a deduction should be made. The appellant submits that the Medical Assessor was in error in failing to make such a deduction.
2. The Medical Assessor said there was no pre-existing condition to be taken into account under s 323 as follows:

"DEDUCTION (IF ANY) FOR THE PROPORTION OF THE IMPAIRMENT THAT IS DUE TO PREVIOUS INJURY OR PRE-EXISTING CONDITION OR ABNORMALITY

1. In my opinion the worker suffers from the following relevant previous injuries, pre-existing conditions or abnormalities:

1. The previous injury, pre-existing condition or abnormality directly contributes to the following matters that were taken into account when assessing the whole person impairment that results from the injury, being the matters taken into account in 10a, and in the following ways:

1. The appellant submitted that the Medical Assessor was in error in so finding and effectively that he did not adequately engage with the evidence in so finding. The appellant seeks an order that the MAC be revoked and a deduction applied for a pre-existing condition under

s 323 of at "least the standard one-tenth." 2. The respondent submitted that the appeal is misconceived and is seemingly based upon the premise that a "frank" injury had been suffered when it is clear that the case, as 'pleaded' in the Application to Resolve a Dispute and as presented in the evidence before the Medical Assessor, was a case of a disease injury based upon the "nature and conditions of employment" rather than an injury simplicitor. The respondent worker submitted the misconceived appeal should fail. 3. The appellant submitted that the Medical Assessor failed to engage with the evidence which included the appellant's statement which referred to injuries prior to the deemed date of

5 April 2011. In referring to the respondent's workers statement the appellant quotes from the statement dated 19 July 2020 as follows:

"I started to notice the onset of pain in my knees over the many years I was employed by Macquarie University. I recall there being around seven (7) separate injuries to my knee during the course of my employment. I cannot recall the exact details of each injury, however I do recall an injury where on one occasion I put my foot in a pothole and twisted my right knee and others where I had been lifting objects or pushing items where I again twisted my knee."

1. The appellant goes onto quote the following paragraph from the respondent's workers statement dated 19 July 2020:

"I recall when I experienced flare ups of the knees I would be treated conservatively and I was directed to rest and take pain relief medication. I also underwent physiotherapy, and this helped ease my symptoms and assisted getting on with the job."

1. The appellant also refers to the worker's statement referencing an injury on

23 December 2008 (at work) and that he was certified unfit for work until January and he stated "my right knee was still giving me grief." 2. The appellant submitted "that this evidence of the respondent worker contradicts the conclusion of the MA and demonstrates that the worker had prior injuries and symptoms to his right knee." 3. The appellant has referred to statement evidence of the respondent worker which does not refer to any injuries prior to the commencement of employment but instead refers to numerous injuries to the knees within the course of employment. 4. There is no medical or other evidence that supports the appellant's contention that the respondent worker had suffered injury to his knees prior to the commencement of employment in 2001. There is no radiology in evidence of the knees prior to employment and the first radiological investigation of the left knee is in 2011 and then X-ray and MRI imaging of both knees in May 2019. 5. The Medical Assessor has very carefully considered the radiological evidence and stated as follows:

"I have viewed x-rays brought in my Mr Robertson from 5 April 2011 of the left knee which revealed no loss of the cartilage intervals. There was therefore no evidence of an impairment on x-rays of the left knee prior to the workplace injury.

X-rays from 8 May 2019 revealed minimal degenerative changes, according to the report. I therefore consider that it is highly unlikely that arthritis was present in both knees prior to Mr Robertson's employment start 2001."

1. The MAC must be read as a whole. The Medical Assessor has taken an adequate history as set out above.
2. A deduction can only be made under s 323 if the pre-existing condition, abnormality or injury has contributed to the overall level of permanent impairment assessed.
3. In this case the history, which is not traversed, is that the respondent worker's knee was asymptomatic at the time of commencement of employment in 2001 and he was able to perform his full duties for the respondent during which he suffered various injuries to his knees.
4. The fact that he was asymptomatic prior to commencing employment is a factor to be taken into account but is not determinative.
5. In addition, there is no radiological evidence or other medical evidence which identifies a condition or abnormality in the knee which pre-existed the commencement of employment.
6. The Medical Assessor has taken an adequate history, reviewed the radiology and other medical evidence before him as well as the other evidence and, noting the nature of the injury that has been referred, has adequately explained why he has not made a deduction under s 323.
7. The Appeal Panel can discern no error in the failure of the Medical Assessor to make a deduction.
8. For these reasons, the Appeal Panel has determined that the MAC issued on 16 May 2025 should be confirmed.