Risteski v Bunnings Group Ltd

Case •

[2022] NSWPICMP 48

•

15 March 2022
DETERMINATION OF APPEAL PANEL
CITATION: Risteski v Bunnings Group Ltd [2022] NSWPICMP 48
APPELLANT: Steve Risteski
RESPONDENT: Bunnings Group Ltd
APPEAL PANEL: Member Catherine McDonald
Dr David Crocker
Dr Roger Pillemer
DATE OF DECISION: 15 March 2022
CATCHWORDS: 

WORKERS COMPENSATION- Section 323 deduction of the Workplace Injury Management and Workers Compensation Act 1998; avascular necrosis (AVN) of humeral head observed on post-injury MRI scan of right shoulder; surgery to acromioclavicular joint and subsequent monitoring of AVN; consequential condition in left shoulder where AVN also present; Medical Assessor deducted one third, speculating that earlier non-work related hip replacements were also the result of AVN; Cole v Wenaline, Ryder v Sundance Bakehouse, Fardell v Clinton Industries referenced; one-tenth deduction was appropriate; Held- Medical Assessment Certificate revoked.

BACKGROUND TO THE APPLICATION TO APPEAL

  1. On 15 November 2021 Steve Risteski lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Dr Yiu-Key Ho, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on 3 November 2021.

  2. Mr Risteski relies on the ground of appeal under s 327(3)(d) of the Workplace Injury Management and Workers Compensation Act 1998 (1998 Act) – that the MAC contains a demonstrable error.

  3. The delegate was satisfied that, on the face of the application, at least one ground of appeal has been made out. We conducted a review of the original medical assessment but limited to the grounds of appeal on which the appeal is made.

  4. The WorkCover Medical Assessment Guidelines 2018 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 the WorkCover Medical Assessment Guidelines 2018.

  5. The assessment of permanent impairment is conducted in accordance with the NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment, 4th ed 1 April 2016 (the Guidelines) and the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th ed (AMA 5).

RELEVANT FACTUAL BACKGROUND

  1. Mr Risteski injured his right shoulder on 17 August 2016 when he lifted several hot water systems each about weighing 25 kg. He continued working until December 2016 when he saw his general practitioner. He was referred to Dr V Kinzel who diagnosed an aggravation of osteolysis in his acromioclavicular joint and operated in April 2017. After a second operation to remove a loose screw, she advised Mr Risteski not to lift weights with his right arm or to raise it above shoulder height.

  2. He returned to work on gatekeeper duties and began to use his left shoulder more because of the limitations imposed by the right shoulder injury.

  3. In a Certificate of Determination dated 27 July 2021, a Member of the Commission determined that Mr Risteski suffered a consequential condition in his left shoulder as a result of favouring his right arm following the injury on 17 August 2016. The assessment of permanent impairment as a result of the injury and the consequential condition was referred to the Medical Assessor.

  4. The Medical Assessor assessed 11% whole person impairment (WPI) in respect of Mr Risteski’s right shoulder and 5% WPI in respect of his left shoulder. He deducted one third of each assessment under s 323 because of the presence of avascular necrosis in both shoulders. He assessed a total of 10% WPI.

PRELIMINARY REVIEW

  1. 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 2018.

  2. As a result of that preliminary review, the Appeal Panel determined that it was not necessary for the worker to undergo a further medical examination because there is sufficient information in the file to determine the appeal.

EVIDENCE

  1. We have all the documents that were sent to the Medical Assessor for the original medical assessment and have taken them into account in making this determination. 

  2. The parts of the medical certificate given by the Medical Assessor that are relevant to the appeal are set out, where relevant, below.

SUBMISSIONS

  1. Both parties made written submissions. They are not repeated in full, but have been considered by the Appeal Panel.

  2. In summary and in submissions prepared by Mr Stockley of counsel, Mr Risteski submitted that the Medical Assessor failed to properly apply s 323 of the 1998 Act because he failed to identify the relevant pre-existing condition or describe how it contributed to the impairment. Mr Stockley said that the Medical Assessor did not explain why the condition caused the assessed impairment to be greater than it otherwise would have been. He said that the Medical Assessor appeared to have relied on evidence which was not available, speculating that earlier and unrelated hip replacement surgery may have been due to avascular necrosis.

  3. In submissions prepared by its solicitor, Mr Orr, Bunnings submitted that the Medical Assessor provided a satisfactory explanation for his deduction of one third for each of his shoulders.

FINDINGS AND REASONS

  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[1] 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.

    [1] [2006] NSWCA 284

  3. The appeal turns on the extent of the deduction which was appropriate to reflect the presence of avascular necrosis in Mr Risteski’s shoulder. There is no appeal with respect to the primary assessments made by the Medical Assessor.

  4. Section 323(1) and (2) provide:

    “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.”

  5. In Cole v Wenaline Pty Ltd, Schmidt J said:

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

    Section 323 does not permit that assessment to be made on the basis of an assumption or hypothesis, that once a particular injury has occurred, It will always, irrespective of outcome', contribute to the impairment flowing from any subsequent injuries. The assessment must have regard to the evidence as to the actual consequence of the earlier injury, pre-existing condition or abnormality. The extent that the later injury was due to the earlier injury, pre-existing condition or abnormality must be determined. The only exception is that provided for in section 323(2), where the required deduction 'will be difficult or costly to determine'.[2]

    …

    What s 323 required, however, was that the evidence be considered, so that it could be determined, firstly, what the level of impairment after the second injury was. Secondly, whether a proportion of that impairment was due to the first injury. Thirdly, what that proportion was. Undoubtedly in undertaking this exercise, the medical members of an Appeal Panel must utilise their medical judgement, knowledge and experience. Nevertheless, all stages of the statutory exercise must be undertaken in the light of the evidence and without the making of assumptions not provided for by the section.[3]”

    [2] At [29]-[30].

    [3] At [38].

  6. In Ryderv Sundance Bakehouse[4] Campbell J said:

    “What s 323 requires is an inquiry into whether there are other causes, (previous injury, or pre-existing abnormality), of an impairment caused by a work injury. A proportion of the impairment would be due to the pre-existing abnormality (even if that proportion cannot be precisely identified without difficulty or expense) only if it can be said that the pre-existing abnormality made a difference to the outcome in terms of the degree of impairment resulting from the work injury. If there is no difference in outcome, that is to say, if the degree of impairment is not greater than it would otherwise have been as a result of the injury, it is impossible to say that a proportion of it is due to the pre-existing abnormality. To put it another way, the Panel must be satisfied that but for the pre-existing abnormality, the degree of impairment resulting from the work injury would not have been as great.”[5]

    And

    “Section 323 as I have already said, requires there to be a deduction for any proportion of the impairment that is due to any pre-existing condition. This is an essential element of the section; indeed it is the pith of it. It is not enough to simply identify that there is a pre-existing condition and that there has been a subsequent impairment and therefore make a deduction under this section because of the existence of the pre-existing condition. Such reasoning fails to consider a necessary condition of the operation of the section; that a proportion of the permanent impairment is due to the pre-existing condition.”[6]

    [4] [2015] NSWSC 526.

    [5] At [45].

    [6] At [54].

  7. Recently in Fardell v Clinton Industries Pty Ltd[7] Harrison AsJ said:

    “From a fair reading of the AMS’ assessment, it would appear that in making a 1/3rd deduction under s 323 of the Workplace Injury Act, the AMS has failed to provide an evidentiary basis in determining whether a proportion of the plaintiff’s current injury was in relation to the previously existing injury and if so what was this proportion. The AMS did not apply steps 2 and 3 of the legal test set out by Schmidt J in Cole. Rather, the reasoning provided for this deduction was that “with the extensive pre-existing condition from 1989, there would reasonably be a significant deduction”. It would appear that the AMS has made his determination on the basis of an assumption or hypothesis that the occurrence of the earlier injury suffered by the plaintiff to his L4/5 will always contribute to impairment following from subsequent injuries, irrespective of outcome and has, as such, fallen into the same error described by Schmidt J in Cole (at [30]). 

    Similarly, the Appeal Panel, in its decision dated 16 April 2021, failed to provide the necessary evidentiary nexus between the first injury suffered by the plaintiff in 1989 and the degree that this injury contributed to the second injury…

    As established in Cole, a deduction is not to be made by way of assessing the impairment that would have resulted from the previous injury and deducting this from the current injury. The Appeal Panel was required to analysis whether and how the previous injury contributed to the current injury and the extent of this contribution. The Appeal Panel failed to recognise an error and then failed to analyse whether and how the previous injury contributed to the current injury and the extent of its contribution.”

    [7] [2022] NSWSC 111 at [79]-[81].

  8. It is appropriate to consider the medical evidence in the file to understand the extent of the pre-existing condition.

Medical evidence

  1. Dr Kinzel noted on 19 January 2017 that an x-ray of Mr Risteski’s right shoulder showed osteolysis of his acromioclavicular joint. We have not been able to locate that x-ray report in the file.

  2. Dr Kinzel anticipated surgery to Mr Risteski’s acromioclavicular joint and ordered an MRI scan to establish the extent of the osteolysis and to see if there was a rotator cuff injury. the MRI scan was undertaken on 20 January 2017 and reported by Dr D Jiang. He said that it showed:

    “Acromioclavicular joint: Mild arthropathy. There is mild cortical irregularity/hyperostosis at the distal clavicle and small focus of subcortical oedema/cystic change. no significant synovitis/effusion.

    …

    Glenohumeral joint

    …

    Cartilage: There is generalised thinning of the articular cartilage at the superior half from the glenoid fossa without a discrete chondral defect or subchondral abnormality. Subjective moderate thinning of the articular cartilage at the opposing medial aspect of the humeral head but without a demonstrable full-thickness defect. There is marked abnormality centred on the subchondral bone at the superomedial aspect of the humeral head characterised by a hypointense line encompassing an area of subcortical bone measuring 20 x 13 x 29mm. Within this and deep to the articular surface is a further fragment of the bone measuring approximately 10 x 5 x 20mm which is scored by fluid signal. There is marked oedema surrounding this abnormality in extending along the humeral metaphysis.

    …

    Appearances are most in keeping with AVN/osteonecrosis of the humeral head with a small fragment of subchondral bone which is scored by fluid signal.

    Background generalised thinning of the articular cartilage without a high-grade defect.

    No secondary features of osteoarthritis.”

  3. On 2 February 2017 Dr Kinzel said that the MRI showed that Mr Risteski’s right acromioclavicular joint was severely diseased causing impingement on the rotator cuff as well as irritation of his biceps tendon. She said that a further “incidental” finding is avascular necrosis (AVN) of his humeral head which has no loose sequestrum. She proposed excision of the distal clavicle and subacromial decompression with possible rotator cuff reconstruction. She wished to discuss the impact of the AVN with a colleague.

  4. She discussed the issue with Dr D Duckworth, who agreed that surgery on the acromioclavicular joint was necessary. Dr Kinzel that the AVN needed to be watched and a repeat MRI scan should be undertaken in six months. Dr Kinzel booked Mr Risteski for right shoulder arthroscopy with a subacromial decompression including the excision of the distal clavicle and possible rotator cuff repair and biceps tenodesis.

  5. In a report to Bunnings’ insurer dated 31 March 2017, Dr Kinzel said that Mr Risteski had symptomatic osteolysis which is often triggered by a fall onto the shoulder or by heavy lifting. She said that his employment was the “sole contributing factor to his current status”. The surgery was undertaken on 6 April 2017 and comprised a right shoulder arthroscopy, acromioclavicular joint resection and biceps tenodesis.

  6. Dr Jiang reported on a further MRI scan on 26 July 2017. He said that the acromioclavicular joint had the expected appearances with residual mild surrounding oedema. In respect of the glenohumeral joint, he said that the labrum was normal but said:

    “Cartilage: There is again generalised thinning of the articular cartilage at the superior glenoid fossa, unchanged. No full-thickness defect. Changes of AVN again seen at the humeral head. The smaller fragment of subcortical bone remains underscored by fluid signal posteriorly over an area of 8 x 8mm but is less conspicuous than on the previous MRI. The larger area of subchondral bone demarcated by a hypointense line is unchanged. There has been reduction in the marrow oedema now considered moderate.”

  7. On 10 August 2017 Dr Kinzel said that the repeat MRI scan showed that the AVN “component” of Mr Risteski’s shoulder was unchanged and in the resolving phase.

  8. Mr Risteski underwent an MRI scan on 4 May 2018 reported on by Dr J Bamidele. It was reported as showing, among other findings:

    “…diffuse oedema with focal serpentine low signal reactive interphase line in the subchondral region of the head of the humerus consistent with avascular necrosis. There are secondary degenerative changes in the gleno-humeral joint.”

  9. The radiologist noted that there was a displaced surgical screw deep in the anterior deltoid fibres with surrounding granulation tissue.

  10. On 10 May 2018 Dr Kinzel said that the AVN had not progressed on the recent MRI scan. Mr Risteski had returned to pre-injury working hours and duties. He continued to have irritation of his acromioclavicular joint and Dr Kinzel recommended a cortisone injection.

  11. On 6 December 2018 Dr Kinzel noted that a recent ultrasound shows that the screw had migrated into the subacromial space and that arthroscopy was required to remove it. She considered that the presence of the screw was the cause of his symptoms. In the following reports she noted that his condition had improved.

  12. On 28 February 2019 and Dr Kinzel noted that Mr Risteski did have some problems with overhead activities. She said he will probably never be a candidate to return to heavy overhead lifting. She said that the ongoing AVN affecting parts of his humeral head meant that he should not do any heavy loading. In August 2019 Dr Kinzel requested a further MRI scan to “ensure that he has reversed his AVN and that the area of his humeral head is now perfused again”.

  13. Dr Jiang reported on the MRI scan on 13 September 2019. He said:

    “Focus of avascular necrosis is again seen, extending over an area of 17 x 11 x 29mm characterised by a circumscribed area of heterogeneous moderate T2 hyperintensity and intermediate Tl intensity with irregularity of the subchondral cortex. Overlying mix partial and full thickness chondral loss which is more prominent than on previous scans. Thinning/partial thickness chondral loss superior glenoid unchanged. No evidence of an unstable fragment.

    Labrum appears generally heterogeneous but otherwise intact.

    Small joint effusion. Possible small loose bodies within the axillary recess.

    ..

    1. Area of avascular necrosis is similar to the previous MRI, no unstable fragment. There is irregularity of the articular cortex and now mixed partial and full thickness chondral loss overlying this focus. Small glenohumeral effusion and possibly small loose bodies/debris within the axillary recess.

    2. Tendinosis but without cuff tear. Mild bursitis.”

  14. On 12 September 2019, Dr Kinzel said that the size of the area of AVN had not changed.

  15. On 13 August 2020 Dr Kinzel noted that Mr Risteski underwent once yearly MRI scans to ensure that the AVN does not increase in size. On 17 September 2020 Dr Kinzel reviewed a further MRI scan of both shoulders undertaken on 8 September 2020 and reported by Dr Jiang. Dr Jiang said in respect of the right shoulder:

    “Acromioclavicular joint: Previous acromioclavicular resection/debridement with expected appearances. Bony irregularity and slight widening of the acromioclavicular interval but no associated Inflammation. Normal acromial morphology but there is bony irregularity/spurring across the acromiale undersurface and anterior bony subacromial spur.

    …

    Glenohumeral joint

    The focus of old avascular necrosis is again seen at the medial aspect of the humeral head. Interval reduction in marrow oedema but otherwise stable appearances. Heterogeneous moderate T2 hyperintense and Tl intermediate intensity signal extending over an area 23 x 10 x 27mm. More focus at the deep aspect of the lesion anteriorly which approaches fluid signal new from previous but no evidence of instability elsewhere. High-grade thinning/full thickness cartilage loss over the anterior aspect is unchanged.

    Remaining humeral cartilage intact. Glenoid cartilage is thinned superiorly but otherwise intact.

    Labral ossification anteriorly/anteroinferiorly, labrum otherwise normal.

    No significant joint effusion.

    Osseous: Small focus subcortical cystic change at the superolateral humeral head. Marrow normal elsewhere.

    …

    1.   Interval reduction in the extent of oedema surrounding the focus of AVN. Apart from a small focus of fluid signal which at the deep aspect anteriorly the focus of AVN appears otherwise stable from the previous MRI. High-grade thinning/full thickness cartilage loss over the anterior aspect of the lesion unchanged. Glenoid and humeral cartilage is intact elsewhere.

    2. Mild supraspinatus tendinosis/tendonitis and mild bursitis.”

  1. In respect of Mr Risteski’s left shoulder, Dr Jiang noted, among other things:

    “Small focus of likely longstanding avascular necrosis at the medial aspect of the humeral head, mild surrounding oedema but no evidence of an unstable fragment.”

  2. Dr Kinzel said that the AVN in Mr Risteski’s right shoulder remained stable and that his humeral head was maintaining its shape and not collapsing. She noted a very small area of old AVN on the left but without any separation and that he had tendinitis affecting his left shoulder for which she recommended a subacromial injection. On 15 October 2020 Dr Kinzel noted that Mr Risteski was developing an “over compensatory injury to his left shoulder as he is not allowed to work with his right shoulder”.

Independent medical examiners

  1. Dr G Burrow examined Mr Risteski on behalf of his solicitor and reported on 24 November 2020. He noted the history of bilateral hip replacements and took a history of Mr Risteski education and work history and of the incident on 17 August 2016. He summarised Dr Kinzel’s treatment, noting her comments with respect to the AVN on the MRI scans and the surgery undertaken. Dr Burrow set out his findings on examination including the range of movement of both shoulders. He said:

    “Stressing the right rotator cuff was remarkably normal at MRC 5. He describes elevation of the shoulder above chest height to cause 'stiffness'. Whilst there was some loss of passive movement, I think he was really describing impingement-type pain, although it was not clear. Definitely there was crepitus about the right shoulder, but
    I could not specifically localise it to the AC joint, or the glenohumeral joint, in particular the known avascular necrosis, noting the ACJ was enlocated, with no local tenderness today and no palpable gap from the distal clavicle surgery.

    I noted no crepitus about the left shoulder. There was a degree of impingement. The AC joint was non-tender. The biceps was not irritable today.

    The distal neurovascular examination was normal.”

  2. Dr Burrow saw only the MRI scan of 4 May 2018. He said:

    “Dr Kinzel says as a side issue, Mr Risteski has avascular necrosis of the humeral head, a constitutional condition unrelated to work. Apparently on serial MR scans the pathology has not changed and there has been no collapse or the development of secondary glenohumeral arthritis to date. Updated imaging is not available to me to confirm this.

    I would expect that the avascular necrosis may well deteriorate with time if it is not fully healed and as such, secondary glenohumeral arthritis will supervene and he may yet need further significant interventional treatment, particularly by way of shoulder replacement.

    If this was to occur, it is due to the constitutional avascular necrosis and not due to the work condition, per se.”

  3. In respect of Mr Ristevski’s left shoulder, Dr Burrow said that there was no apparent crepitus which might suggest bilateral AVN. He considered that the prognosis for the right shoulder condition is largely good, considering only the acromioclavicular joint and biceps and said:

    “Right shoulder humeral head avascular necrosis: This condition is constitutional and probably coincidental. I have some concerns that some of the symptoms that Mr Risteski may have complained of originally could possibly have been from the avascular necrosis, but Dr Kinzel, experienced Orthopaedic and Shoulder Surgeon, specifically found symptoms and physical signs related to the biceps and AC joint and has dealt with those areas. If the avascular necrosis deteriorates over time and the humeral head collapses, he will develop arthritis and require further non-operative and operative treatment including perhaps shoulder replacement or resurfacing procedure. This is not, however, related to the work condition.

    …

    The left shoulder prognosis is unknown as the specific diagnosis has not been confirmed to date. Recent investigations are not available to me. I would be specifically interested to learn whether the MR scan excludes avascular necrosis of the humeral head. If that is subsequently diagnosed in the left shoulder, a referral to an Endocrinologist or a Rheumatologist would be helpful to delineate a constitutional cause for the poly-joint AVN. I would also like to learn whether the hip replacement surgery aetiology was for simple osteoarthrosis or also included avascular necrosis.”

  4. There is nothing in the file to suggest that Dr Burrow was provided with any further information or asked to revisit his report. He considered that any acromioclavicular joint degenerative arthritis was due to the condition itself and therefore did not make a deduction under s 323.

  5. Dr R Wallace examined Mr Risteski on behalf of Bunnings. At the time of his first report on 29 March 2017, Mr Risteski was awaiting surgery. He considered that the right shoulder condition was due to the work injury on 17 August 2016 with a proportion being due to pre-existing degenerative osteoarthritis at the acromioclavicular and glenohumeral joints. He considered that employment was a substantial contributing factor to the condition and that surgery was appropriate.

  6. Dr Wallace saw Mr Risteski again on 4 February 2021. He considered that the right shoulder condition was due to the work injury with a proportion been due to pre-existing degenerative osteoarthritis involving the acromioclavicular and glenohumeral joints. He did not consider that there was any work-related injury to Mr Risteski’s left shoulder. In making an assessment of permanent impairment he deducted the impairment assessed in respect of the left shoulder from that assessed in respect of the right. He did not make any significant statement about the presence of AVN.

The MAC

  1. The Medical Assessor took a brief history of the injury and summarised Dr Kinzel’s treatment and the findings of the MRI scans:

    “He was referred to see Dr Kinzel. There was certainly a concern about the avascular necrosis. Apparently Dr Kinzel discussed with some other colleagues and still decided for arthroscopic surgery which was done on the 6 April, 2017. Basically the subacromial debridement mainly on the AC joint together with bicep tenodesis. The surgery was not too successful and repeated MRI was done, actually in July, 2017, just over three months after the surgery. There was already suggestion that the tenodesis screw for the bicep has migrated. The avascular necrosis has not changed. Further MRI was done on the 4 May, 2018, this time further migration of the screw was noticed and the AVN had deteriorated and started to cause osteoarthritis of the glenohumeral joint. He was regularly followed up by Dr Kinzel but somehow there was no discussion about the migration of the screw and ultimately further ultrasound on the 29 November, 2018, the screw had migrated further up in the subacromial bursa. At that point it was noticed by Dr Kinzel and the removal of the screw was done on the 13 December, 2018. Further MRI was done and was showing further deterioration of the osteoarthritis of the right shoulder joint. In about one year after the second operation, that was the end of 2019, he started to complain about problem of the left shoulder. It remained sore and stiff and he was referred to see Dr Kinzel again. MRI of both shoulders done on the 8 September, 2020, we can see more evidence of cartilage loss of the right shoulder and the left shoulder also has a small area of avascular necrosis but did not show obvious cartilage loss. For the left shoulder Dr Kinzel just recommended conservative treatments.”

  2. The Medical Assessor described Mr Risteski’s present symptoms:

    “He notices more pain on the left shoulder because that is probably the arm he uses more because the right shoulder remains sore and stiff and weak due to ongoing process of degeneration.”

  3. He noted that Mr Risteski had had bilateral hip replacements before he turned 50 but said he did not know why. He summarised the MRI scans dated 20 January 2017 and 8 September 2020 only.

  4. The Medical Assessor summarised the injuries and his diagnoses:

    “My [sic] Steve Risteski had a lifting injury on the right shoulder back in 2016 and complained of pain in the right shoulder. Investigation at that time confirmed mild AC joint arthritis but it has an obvious AVN focus in the right humeral head. He end up with shoulder surgery with decompression of the AC joint and bicep tenodesis. The surgery probably complicated with the migration of the screw for the tenodesis because it migrated at the first MRI follow up four months after the operation and then subsequently the screw completely loosened and gone up to the subacromial space. The second operation for the removal of the screw was only done nearly two years from the first operation in December, 2018. One year after the second operation in late 2019 he developed problem of the left shoulder treated as consequential injury. Investigation of the left shoulder also showing similar pathology of avascular necrosis of the left femur [sic] head.”

  5. In giving the reasons for his assessment the Medical Assessor said:

    “I believe this gentleman had a lifting injury on the right shoulder and developed problems with pain and loss of function. But the initial MRI already showed avascular necrosis together with only mild changes of AC joint OA. Patient end up with shoulder surgery which did not give a good result as it was a decompression of the AC joint and bicep tenodesis and the tenodesis screw migrate. It was shown on the MRI four months after the surgery and then subsequent investigations showed the whole screw become free in the subacromial bursa and ultimately the screw was only removed more than one and half years after it was put in and migrated out. We certainly see progression of the right shoulder problem, not in the size of the AVN but we see more evidence of chondral loss of thinning, in other words he is developing shoulder osteoarthritis. The problem of the left shoulder can be considered as the consequential problem of favouring of the right shoulder. But once again we see a similar pathology of AVN of the left shoulder. So obviously there are contribution from pre existing condition on both shoulders. As a matter of fact this gentleman had bilateral hip replacement done when he was very young. He did not know the underlying reason but maybe it can also be related to avascular necrosis of the femoral head. All that just pin points to the contribution from pre-existing condition when we are doing the assessment of the whole person impairment. I believe based on the examination on the 28 October, 2021, both shoulders are showing inferior function and there is permanent impairment with the right side being worse.”

  6. The Medical Assessor set out the range of movement he observed in each of Mr Risteski’s shoulders. He said:

    “The loss of movement accounts for 9% upper limb impairment which gives rise to a 5% whole person impairment. I think there will be contribution from pre-existing condition. In my opinion I would deduct at least 1/3 because there is significant problems with AVN and then cartilage loss ending up with glenohumeral joint OA, quite obvious on the right shoulder at the moment and is going to have similar effect on the left shoulder. So with the right shoulder after the deduction will leave behind 7% whole person impairment. On the left shoulder will leave behind 3% and when the two are combined together it is 10%.”

  7. The Medical Assessor commented on Dr Burrow’s report:

    “My clinical examination is inferior to Dr Burrow when patient was assessed by him a year ago especially on the right shoulder which is explained by the deterioration due to the ongoing development of osteoarthritis. I am sure if we are going to do further MRI at this point it will be showing more problem of chondral loss. I cannot agree with him that there is no deduction. Maybe the reason is he did not know the left shoulder also has avascular necrosis. Bilateral avascular necrosis of the humeral head would be some pre-existing problem contributing to that and certainly as mentioned in my report in previous section he had bilateral hip replacement when he was less than fifty years old although he did not know the pathology there would be possibility that AVN is also playing a part.”

  8. When explaining the s 323 deduction, the Medical Assessor said:

    “I deduct 1/3 for pre-existing problem as he had AVN of both humeral head and we can see the gradual deterioration of the right shoulder with MRI demonstrating further loss of cartilage and development of osteoarthritis with time. Hence I assessed it higher than the 1/10 rule which is usually asymptomatic from this preexisting condition.”

Consideration

  1. Bunnings accepts that Mr Risteski suffered an injury in the manner described. The clinical features on his initial presentation were consistent with an injury to his acromioclavicular joint and biceps tendon in the workplace injury. There was a co-existent finding of AVN present on the first MRI scan.

  2. Dr Kinzel operated on Mr Risteski’s acromioclavicular joint. The surgery was not related to the area of AVN. She recognised that the AVN was present, significant and should be monitored and Mr Risteski underwent six-monthly MRI scans at least until September 2020. Over that period, she noted that the area of AVN had not substantially changed. The radiologists compared the scans to those undertaken previously.

  3. Dr Burrow clearly identified the difference between the injury and the AVN. Based on Dr Kinzel’s reports rather than the MRI scans or their reports, Dr Burrow said that there had been no collapse of the humeral head and no development of secondary glenohumeral arthritis. The latter was the anticipated consequence if the AVN deteriorated and in that case a shoulder replacement may be required. Dr Burrow said that shoulder replacement surgery would not be related to the injury.

  4. Dr Wallace’s opinion is less clear but he nonetheless distinguished between degenerative arthritis of the acromioclavicular joint and of the glenohumeral joint.

  5. The Medical Assessor expressed some opinions which are not consistent with the contemporaneous evidence. He said that the surgery was “not too successful” so that an MRI scan was carried out three months later. The indication for the MRI scan in Dr Kinzel’s report dated 26 June 2017 was the expiration of six months since the last one because of the need to monitor the progression of AVN. There is no suggestion in Dr Kinzel’s reports that the surgery was not initially successful.

  6. The Medical Assessor was critical of Dr Kinzel for not taking steps to deal with the displaced tenodesis screw before December 2018.

  7. The Medical Assessor accepted that the area of AVN in Mr Risteski’s right shoulder had not changed in the MRI scans up to September 2020. He said that the progression of the shoulder problem was the thinning of cartilage and the development of osteoarthritis. The Medical Assessor said that there was an obvious contribution to Mr Risteski’s condition from a pre-existing condition in both shoulders but did not explain why.

  8. The Medical Assessor speculated that Dr Burrow had not made a s 323 deduction because he was unaware of the AVN in Mr Risteski’s left shoulder. He stressed that Mr Risteski was young to have undergone bilateral hip replacements and that “maybe” it was related to avascular necrosis of the femoral head.

  9. There is nothing in the file to indicate why Mr Risteski underwent hip replacements other than a reference to osteoarthritis in the general practitioner’s notes on 10 March 2015[8]. The connection drawn by the Medical Assessor is speculative and not available on the evidence.

    [8] Application to Resolve a Dispute p 85.

  10. The reason the Medical Assessor ultimately expressed for the deduction is the existence of AVN and the development of osteoarthritis - in particular the thinning of cartilage in the gleno-humeral joint with time.

  11. In the last MRI scan report on 8 September 2020, Dr Jiang said that there was an interval reduction in the extent of oedema surrounding the focus of AVN but the AVN appeared otherwise stable. The high grade thinning/ full thickness cartilage loss over the anterior aspect of the lesion was said to be unchanged. The Medical Assessor’s opinion that there was “more evidence of chondral loss of thinning”[sic] is inconsistent with the opinion of the radiologist and he did not say why his reading of the scans differed.

  12. It is likely that AVN and degenerative arthritis are playing a role in the current condition of Mr Risteski’s shoulders. However, the Medical Assessor was required to apply s 323. He was required to determine the extent of contribution from the previous condition to the injury. He was not entitled to assume the extent to which the condition contributed to the impairment flowing from the injury and he was required to provide the evidentiary nexus to explain the deduction he made. He did not do so, confirmed by his statement that there was obviously a contribution. His speculation as to the cause of Mr Risteski’s hip replacements highlights the error. For this exercise, the hip replacements are irrelevant.

  13. In this case the extent of the contribution from the pre-existing conditions is difficult to determine. In the absence of a scan before January 2017 – at least four months after the injury – it is not possible to understand the extent of the pre-existing AVN or cartilage thinning. It is likely that the AVN and degenerative changes pre-existed the injury. It is also likely that those conditions are contributing to the restriction of the loss of the range of movement in Mr Risteski’s shoulders. Because the impairment resulting from the injury is assessed by measuring the range of motion, a deduction is appropriate.

  14. This is the kind of case envisaged by s 323(2) because the extent of the deduction will be difficult to determine. Despite the pre-existing condition, Mr Risteski was able to undertake his duties until the injury in August 2016. A deduction of one-tenth of the impairment is not at odds with the available evidence.

  15. For these reasons, the Appeal Panel has determined that the MAC issued on 3 November 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 Yiu-Key Ho 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)

Right upper extremity (shoulder)

17 August 2016

Chapter 2

Figure 16-40, 43, 46
Table 16-27

11%

1/10

10%

Right upper extremity (shoulder)

17 August 2016

Chapter 2

Figure 16-40, 43, 46
Table 16-27

5%

1/10

5%

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

15%

Catherine McDonald

Member

David Crocker

Medical Assessor

Roger Pillemer

Medical Assessor

15 March 22


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Cases Cited

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Statutory Material Cited

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