DETERMINATION OF APPEAL PANEL	
	
CITATION:	Secretary, Department of Communities and Justice v Dykes [2024] NSWPICMP 333	
		
APPELLANT:	Secretary, Department of Communities and Justice	
		
RESPONDENT:	Kerrie Dykes	
		
Appeal Panel		
		
MEMBER:	Marshal Douglas	
		
MEDICAL ASSESSOR:	Doron Sher	
		
MEDICAL ASSESSOR:	David Crocker	
		
DATE OF DECISION:	27 May 2024	
		
CATCHWORDS: 	wORKERS cOMPENSATION - Workplace Injury Management and Workers Compensation Act 1998; whether rating of lower extremity impairment by reference to Table 17-22 of AMA 5 for patella subluxation or dislocation with residual instability was properly explained; whether rating of lower extremity impairment by reference to Table 17-22 of AMA 5 for patella subluxation or dislocation with residual instability was supported by the evidence; whether the assumption that Medical Assessor (MA) made under section 323(2) that deductible proportion for section 323(1) was 10% was at odds with the evidence; Appeal Panel held MA adequately explained his assessment and that the findings he made and history he obtained supported application of Table 17-33; Appeal Panel held section 323(2) assumption was not at odds with the evidence; Held – Medical Assessment Certificate upheld.

   	

BACKGROUND TO THE APPLICATION TO APPEAL
1.	On 20 March 2024 the Secretary of the Department of Communities and Justice, the appellant, lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Dr Mark Burns, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on 21 February 2024.
2.	The appellant relies on the following grounds of appeal under s 327(3) of the Workplace Injury Management and Workers Compensation Act 1998 (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) for appeal on which the appeal is made. 
4.	Rule 128 of the Personal Injury Commission Rules 2021 (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). 
RELEVANT FACTUAL BACKGROUND
6.	The appellant employed Mrs Kerrie Dykes as a senior client services officer from around 2009. On 9 June 2020 she suffered an injury to her left knee which occurred when she twisted her knee after quickly turning whilst standing at a printer. She felt three sharp cracks across the middle of her knee. 
7.	She consulted her general practitioner (GP) on the same day who referred her for an MRI scan that was done on 4 July 2020. The radiologist who reported on that scan provided the following conclusion regarding what it revealed: 
“Osteoarthritic changes with grade 4 chondromalacia in the medial and patellofemoral compartments. Subtle cortical depression with subcortical pitting and bony oedema in the medial femoral condyle overlying which there is a 5x8 mm full thickness chondral ulcer present. Extruded, macerated and torn anterior horn and body of the medial meniscus. Subtle tear body of lateral meniscus close to its free edge. Grade 1 strain proximal LCL and popliteus tendon. Joint effusion and intra-articular loose bodies.”    
8.	The respondent’s GP referred the respondent to orthopaedic surgeon Dr Simon Coffey who examined her on 21 July 2020.  Dr Coffey wrote to the respondent’s GP advising him he had made a diagnosis of “acute exacerbation osteoarthritis left knee with medial compartment stress fracture”. 
9.	Dr Coffey wrote to the appellant’s insurer on 11 August 2020 advising the same diagnosis, but also expanding on it by saying that the respondent had sustained an acute exacerbation of pre-existing but minimally symptomatic osteoarthritis of her left knee and that she had developed, as a result of her injury, a stress fracture of the sub condyle bone of the medial tibial plateau. Dr Coffey noted the respondent had a past history of left knee arthroscopy and partial meniscectomy. Dr Coffey noted that the respondent, prior to her injury, had residual low grade symptoms in her left knee but was able to participate in all of her daily activities and work related duties. Dr Coffey advised that the respondent required intervention and that the only reasonable intervention was a total knee replacement. 
10.	Dr Coffey performed a total knee replacement on 9 November 2020. In his operation report regarding that, he recorded his intraoperative findings were advanced medial chondropathy, moderate trochlear chondropathy, moderate synovitis and intact ACL. 
11.	The respondent continued to experience symptoms of pain following her surgery. Dr Coffey made a diagnosis of patellofemoral instability. He undertook a revision of the left knee arthroplasty on 3 August 2021 as well as ligament augmentation and reconstruction and ligament reinforcement and medial retinaculum. 
12.	On 28 June 2023 the respondent’s solicitors wrote to the appellant’s solicitors advising that the respondent claimed compensation under s 66 of the Workers Compensation Act 1987 (the 1987 Act) for 33% whole person impairment (WPI) from her injury to her left knee on 
9 June 2020. The respondent’s solicitors advised that the respondent relied on reports of orthopaedic and spinal surgeon Dr Charles New dated 17 March 2022 and 26 June 2023, and enclosed copies of those reports with its correspondence.
13.	Following that, the appellant’s solicitors organised for the respondent to be examined by orthopaedic surgeon Dr Gothelf on 5 September 2023. Dr Gothelf had examined the respondent on two prior occasions. He provided the appellant’s solicitors with a report dated 20 September 2023 relating to his examination of the respondent on 5 September 2023 in which he advised that he assessed the respondent had 20% WPI as a consequence of her left knee replacement but in terms of the degree of permanent impairment from her injury, 
Dr Gothelf advised he considered three quarters of the respondent’s impairment relating to her knee was due to a pre-existing osteoarthritis, such that he assessed that the degree of her permanent impairment from her injury insofar as it related to her knee replacement was 5% WPI. He also assessed she had 1% WPI relating to her scarring from surgery, such that he assessed she had 6% WPI from her work injury. 
14.	On 3 November 2023 the appellant’s insurer notified the respondent pursuant to s 78 of the 1998 Act that it denied liability with respect to her claim for compensation under s 66. It advised her this is because her permanent impairment from her injury was not more than 10% as required by s 66 of the 1987 Act. It advised her that it relied upon the report of 
Dr Gothelf dated 20 September 2023. 
15.	That precipitated the respondent initiating proceedings in the Personal Injury Commission (Commission) seeking determination of her claim. Upon her doing so, and the appellant filing a reply to her application, a delegate of the President referred the matter to the Medical Assessor to assess the various medical disputes between the parties relating to her claim, which included the degree of permanent impairment resulting from her injury and whether any proportion of permanent impairment is due to any previous injury or pre-existing condition or abnormality and the extent of that proportion. 
MEDICAL ASSESSMENT CERTIFICATE
16.	The Medical Assessor detailed in the MAC the circumstance that gave rise to the respondent’s injury and also detailed the treatment she had received for that, including the total knee replacement done on 9 November 2020 and its subsequent revision with ligament reconstruction and reinforcement. The Medical Assessor recorded the symptoms the respondent had suffered following her injury. He also recorded her current symptoms included pain in the shape of a V which goes below her patellar and which is sharp in nature occasionally, and mostly felt as a strong ache and is dependent on her level of activity. 
17.	The Medical Assessor recorded in the history he obtained from the respondent that following her surgery she still felt her patellar slide occasionally and that her knee continued to lock occasionally associated with what she believed was subluxation of the patellar. 
18.	The Medical Assessor detailed the following clinical history relating to the respondent’s left knee prior to the respondent suffering her work injury: 
“She reported that at the age of 16 or 17 she fell down some steps at work and injured her left knee. Surgery was carried out in the form of advancement of the vastus medialis. Following this operation, she was able to return to her previous sport and normal activities.
In 2012 she sustained a further injury to the left knee and was diagnosed with a torn medial meniscus. Dr Rizkallah, Orthopaedic Surgeon carried out a partial medial meniscectomy. I note from Dr Coffey’s report dated 11 August 2020 that after this surgery she had residual low-grade symptoms in the left knee but was able to participate in all her desired daily activities and work related duties. In point 4 of the same report he states, ‘Mrs Dykes has sustained an acute injury resulting in progression of osteoarthritis to the left knee. She requires intervention. Total knee replacement is the only reasonable intervention that will offer durable symptom relief and return to function’.
Ms Dykes confirmed that she did have occasional pain and discomfort in the left knee following the partial medial meniscectomy, but she was able to do all the activities at work and at home.”
19.	The Medical Assessor provided brief details of the radiological investigations the respondent had done on her knee subsequent to her injury and also the results of a bone scan. These included the results of the MRI scan done of the respondent’s left knee on 4 July 2020 prior to the respondent’s total knee replacement. The Medical Assessor noted this investigation revealed: 
“[O]steoarthritis with grade 4 chondromalacia in the medial and patellofemoral compartments. Some sub-cortical pitting and bony oedema over the medial femoral condyle was noted, which would be consistent with a stress fracture. A grade 1 strain of the proximal lateral collateral ligament was also noted.”
20.	The Medical Assessor recorded in the history he obtained from the respondent that following her surgery she still felt her patellar slide occasionally and that her knee continued to lock occasionally associated with what she believed was subluxation of the patellar. The Medical Assessor recorded his findings from his examination of the respondent’s left knee in the following terms: 
“Ms Dykes was 171cms tall and weighed 99.1kgs. She was noted to walk with an
antalgic gait favouring her left leg.
Left lower extremity:
Examination of both knees revealed no evidence of localised tenderness on the right
side but mild medial tenderness on the left side. Active range of movement in both
knees was measured using a goniometer.
Knee movements	Active ROM Measured
Right	Active ROM Measured 
Left	
Flexion	120°	115°	
Extension	0°	0°	
It was noted that both knees were in 5° valgus angulation. There was mild crepitus in
the patellofemoral joint in both sides. It was slightly less on the left than the right.
There was no evidence of AP instability in either the left knee or the right knee. There was also no evidence of ML instability in the right knee but mild ML instability in the left knee.
The circumference of the right quadriceps 10cms above the patella was 53cms compared to 51.5cms on the left. The circumference of the right mid-calf was 43.5cms compared to 43cms on the left. It was noted that she had mild wasting in the medial
quadriceps on the left side.
Examination of the patellofemoral joint on the left side revealed some lateral instability. She had a positive apprehension test for possible lateral dislocation of the patella.”
21.	The Medical Assessor also recorded his findings from his examination of the respondent’s scarring on her left knee. The Appeal Panel has not repeated these in this statement of reasons because neither party raised an issue with the Medical Assessor’s rating of the respondent’s permanent impairment due to her scarring. 
22.	The Medical Assessor assessed the respondent’s permanent impairment relating to her knee replacement by reference to Table 17-35 of AMA5, as amended by paragraph 3.30 of the Guidelines. Based on the points the Medical Assessor scored for the various criteria listed in that amended table the Medical Assessor rated the respondent’s impairment relating to her total knee replacement as fair which accords with 50% lower extremity impairment. The appellant does not challenge that assessment in his appeal against the MAC. 
23.	The Medical Assessor made a deduction of 10% of that when assessing the degree of the respondent’s permanent impairment from her injury insofar as it related to her left knee replacement. The Medical Assessor explained he did that because, firstly, the respondent had a past history of injury going back to 16 years of age with a partial medial meniscectomy that was done around eight years ago, secondly, the MRI scan done shortly after her injury revealed significant pre-existing degenerative change mostly in the patellofemoral and medial compartments and, thirdly, the respondent had an asymptomatic left knee before her injury. With respect to the latter matter, the Medical Assessor took into account that prior to the respondent suffering her injury she was able to do full activities both around her house and within her work. The Medical Assessor explained in the MAC that he thought the deduction to be made under s 323(1) of the 1998 Act would be difficult or costly to determine so he applied “the provisions of s 323(2) to assess the deductible proportion as 1/10th”. 
24.	The Medical Assessor observed that Dr Gothelf had made a deduction of 66%, and the Medical Assessor considered that deduction is “far too high” and expressed his belief that a deduction of 1/10th “is more appropriate”.
25.	Hence, the Medical Assessor assessed that the respondent’s impairment resulting from her work injury, insofar as it involved her left knee replacement, was 45% lower extremity impairment. 
26.	The Medical Assessor also explained in the MAC that he assessed the respondent had 7% lower extremity impairment pursuant to the criteria listed in Table 17-33 of AMA5 relating to patellar subluxation and residual instability. The Medical Assessor explained that 7% lower extremity impairment relating to that when combined with the 45% lower extremity impairment he assessed the respondent had relating to her knee replacement resulted in 49% lower extremity impairment, which converted to 20% WPI. 
27.	The Medical Assessor also assessed the respondent had 2% WPI relating to scarring, which when combined with the 20% WPI relating to her left knee injury, combined to 22% WPI, which the Medical Assessor certified was the degree of permanent impairment he assessed the respondent had resulting from her injury. 
PRELIMINARY REVIEW
28.	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.
29.	As a result of that preliminary review, the Appeal Panel determined that it was not necessary for the respondent 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 there was no basis for the Appeal Panel to examine the appellant.
EVIDENCE
30.	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.  
SUBMISSIONS 
31.	Both parties made written submissions. They are not repeated in full, but have been considered by the Appeal Panel. 
32.	In summary, the appellant submitted that the information the Medical Assessor recorded in the MAC did not make it clear that the respondent suffered from a patellar subluxation or residual instability such that an assessment could be made of lower extremity impairment by reference to the criteria in Table 17-33 for patellar subluxation or dislocation with residual instability. The appellant noted that neither Dr New nor Dr Gothelf had included in their respective assessments of the respondent’s permanent impairment from her injury any rating for patellar subluxation with residual instability. The appellant submitted that there was nothing within the medical evidence to reveal the respondent had patellar subluxation of the left knee. The appellant submitted that, absent the respondent having patellar subluxation, the Medical Assessor was incorrect to include a rating for that. 
33.	The appellant submitted that the Medical Assessor’s finding that the respondent had instability of her left knee was not supported by other medical evidence. The appellant submitted that the Medical Assessor’s findings from his examination that the respondent had instability was not well explained by the Medical Assessor. 
34.	The appellant submitted that the respondent had extensive pre-existing left knee pathology. The appellant highlighted parts of the evidence that the appellant considered confirmed that. The appellant also highlighted parts of the MAC wherein the Medical Assessor recorded the respondent’s history of left knee complaints. The appellant submitted that Dr Gothelf provided an extensive explanation why he made a greater deduction than 1/10th, with his reasons including that:
(a)	the respondent had surgery at age 18;
(b)	the respondent’s injury was an exacerbation of existing osteoarthritis in her knee;
(c)	it was likely that the respondent’s knee symptoms would have eventually occurred regardless of the incident by which she suffered injury, and
(d)	the MRI scan revealed arthritic changes and that had a substantial influence on the surgery the respondent had and her final impairment. 
35.	The appellant submitted that a deduction of 1/10th is not consistent with the medical evidence. The appellant submitted that the Medical Assessor did not consider properly the respondent’s extensive history relating to her left knee when assessing the degree of permanent impairment, she had. 
36.	In reply, the respondent submitted that the Medical Assessor found from his clinical examination of her that she had lateral instability of her patellofemoral joint. The respondent also highlighted that the Medical Assessor stated he made a positive finding on a patellar apprehension test for possible lateral dislocation of the patellar. The respondent submitted that the Medical Assessor’s findings regarding patellar subluxation and instability was based on his clinical judgement and provided a proper basis for assessing 7% lower extremity impairment under Table 17-33. 
37.	The respondent submitted that the Medical Assessor made no error by making a deduction of 1/10th under s 323. The respondent submitted that the approach that Dr Gothelf adopted when determining what deduction should be made under s 323 was erroneous in that he looked at the probability of future symptomology rather than basing the deduction on the proportion to which the pre-existing condition contributed to the impairment at the time of assessment. 
FINDINGS AND REASONS 
38.	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. 
39.	In Campbelltown City Council v Vegan [2006] NSWCA 284 the Court of Appeal held that the Appeal Panel is obliged to give reasons. 
40.	The Medical Assessor was correct, based on, firstly, the history he obtained from the respondent that her patellar would slide to the lateral side and that her knee would lock, and, secondly, his finding from his examination of the respondent that she had mild medial ligament instability in her left knee and lateral instability of her patellofemoral joint on the left side with a positive apprehension test for possible lateral dislocation of the patellar, to conclude that the respondent had patellar subluxation or dislocation with residual instability. He was therefore correct to assess, by reference to the criteria of Table 17-33 of AMA5, that the respondent had 7% lower extremity impairment from her injury on account that. 
41.	It does not matter that neither Dr New nor Dr Gothelf had found the respondent had that impairment of her left knee. Given that respondent’s claim related to permanent impairment resulting from an injury to her left knee, their respective assessments of the respondent’s permanent impairment did not confine the medical dispute the Medical Assessor had to assess to the criteria they applied. The Medical Assessor was not bound by their conclusions, and had to make his assessment based on how the respondent presented at examination. 
42.	The Appeal Panel does not accept the appellant’s submission to the effect that the Medical Assessor did not justify his finding of residual instability. He did so by setting out his findings from his examination and also setting out the history he obtained relating to the respondent’s history of symptoms. 
43.	The deduction to be made under s 323(1) of the 1998 Act is for that part or portion of a worker’s permanent impairment that is due to a pre-existing condition and not the workplace injury. That is, a Medical Assessor must be satisfied that a worker’s degree of permanent impairment is greater than it otherwise would have been as a result of the injury because of the pre-existing condition or abnormality. 
44.	That determination must be based on the evidence, and not on assumption or hypothesis, except in the circumstance described in s 323(2) of the 1998 Act, which is where it would be difficult or costly to determine the deduction to be made, in which case the Medical Assessor is required to assume the deduction is to be 10% unless that assumption would be at odds with the evidence. 
45.	It is uncontroversial in this matter that the respondent had a pre-existing condition in the form of degeneration in her right knee. Indeed, in the Appeal Panel’s view, the MRI scan done shortly after the respondent suffered injury, revealed that the degeneration in her left knee, as at the time of injury would have been substantial, which is unsurprising given her previous injury and the surgery she had for that. 
46.	It is also uncontroversial in this matter that a deduction was required to be made under s 323(1) of the 1998 Act because of the pre-existing degeneration in the respondent’s left knee. In other words, there is no controversy between the parties that part of the respondent’s permanent impairment was due to her pre-existing condition and not her workplace injury. The controversial issue in this matter is what that part or portion was. 
47.	In this matter, the Medical Assessor found that the respondent had pre-existing degeneration in her left knee which generated some symptoms prior to her suffering injury. The Medical Assessor noted that the respondent had prior surgeries. 
48.	The Appeal Panel considers that the Medical Assessor was correct to assume that it was difficult to determine exactly what part of the respondent’s left knee permanent impairment is due to pre-existing degeneration in her left knee. The Medical Assessor did not state explicitly in the MAC why it was difficult, but in the view of the Appeal Panel, which is an expert panel, it is difficult because the respondent’s impairment relating to her left knee arises in large part as a consequence of her having an artificial joint. Her need for that artificial joint is a consequence of both the pre-existing degeneration she had in her knee and the manifestation of significant symptoms from that degeneration as a consequence of her exacerbating that condition by her injury. Where there is a combination of factors that gave rise to surgery that has resulted in a worker having a permanent impairment it will almost invariably be the case that it will be difficult to determine, with any scientific precision, what factor produced a specific part of the worker’s impairment. In that circumstance, the Medical Assessor must apply s 323(2) and assume the portion due to the pre-existing factor is 10% unless that assumption is at odds with the evidence. 
49.	Consequently, in the Appeal Panel’s view, the Medical Assessor did not make any error in this case, provided the assumption that the deductible proportion was 10%, which is what he assumed it to be pursuant to s 323(2), was not at odds with the evidence. 
50.	In this case, the relevant evidence was that the respondent had extensive osteoarthritis in her left knee, which although generating some symptoms for her preceding her injury, did not inhibit her from engaging in any activity, including her work. Following her injury, she experienced persistence of pain and swelling such that she was unable to undertake her daily activities and undertake her work. Dr Coffey indicated that the only realistic option was for the respondent to have a total knee replacement because of that. Whilst it is most likely the case, given the degeneration that was in the respondent’s left knee at the time of injury, the respondent would have required that surgery at some future time if she had not suffered injury, it cannot be known from the evidence when that would have occurred. In other words, her suffering injury accelerated her need for a total knee replacement, by reference to which her permanent impairment is assessed. Further, as a consequence of her having that surgery the osteoarthritic disease in her knee has now been completely or largely removed. That is, it no longer contributes to her impairment, notwithstanding that it contributed to her need for surgery. 
51.	Whilst the Appeal Panel considers that the Medical Assessor could have been more fulsome in explaining why assuming the deductible proportion was 10% was not at odds with the evidence, when evidence that the Appeal Panel has just outlined is weighed, the Appeal Panel considers that the assumption that the deductible proportion is 10% is not at odds with it.
52.	Simply put the Appeal Panel considers that, based on the matters the appellant raised in his submissions to support his appeal, there is no error in the MAC as a consequence of the deduction the Medical Assessor made. 
53.	For completeness, the Appeal Panel notes that given the surgery the respondent had to her left knee prior to her injury to her left knee, she would have in all likelihood had instability in her left knee. Consequently, the Appeal Panel considers that a deduction ought to be made under s 323(1) with respect to the assessment the Medical Assessor made by reference to the criteria of Table 17-33 of the AMA5. Further, the Appeal Panel considers that that deduction ought to have been assumed to have been 10% pursuant to s 323(2), and this is because prior to the respondent’s injury there is no evidence that indicates instability was causing her any significant concern, whereas following her injury it has. Again, this is a matter where it is difficult to determine the precise part of her current impairment relating to that pre-existing condition, such that it can be assumed under s 323(2) that the deduction should be 10%, which is not at odds with the evidence. The Appeal Panel merely notes this for the sake of completeness, given that neither party raised this as an issue in the appeal. It would make no difference in any event to the outcome in this matter. 
54.	For these reasons, the Appeal Panel has determined that the MAC issued on 
21 February 2024 should be confirmed.