1. The Commission finds that the applicant suffers 17% whole person impairment as a result of the injury in the employ of the respondent which is deemed to have occurred on 16 January 2025, and
2. I make no order.

A statement is attached setting out the Commission's reasons for the determination.

1. Carolyn Shanahan was employed by Illawarra Retirement Trust (IRT) as a part-time care worker when she suffered an injury to her back. The injury is deemed to have occurred on 16 January 2019.
2. Ms Shanahan began working for IRT in about 2007. She first suffered injury on 28 September 2011 when she developed low back pain while cleaning a toilet. She underwent an MRI scan on 17 November 2011 which showed a posterocentral left L4/5 disc protrusion. Her treatment was conservative. She suffered flareups at work in August 2014 and in 2017, after which she began to have altered sensation in her leg. Ms Shanahan saw A/Prof Jaeger, neurosurgeon, for the first time on 13 March 2018. He ordered an MRI scan which was reported on 26 March 2018 as showing a small left posterolateral disc protrusion at L3/4.
3. On 7 May 2018 A/Prof Jaeger informed Ms Shanahan that she would need to consider a left L3/4 far lateral microdiscectomy and rhizolysis.
4. Ms Shanahan developed further low back pain in October 2018 while making a client's bed. She underwent surgery on16 January 2019. A/Prof Jaeger wrote to IRT's insurer on 21 January 2019 and said:

"Ms Shanahan underwent an up to date MRI scan on 15/1/19 performed at Wollongong Hospital. Compared to the previous scan from 26/3/18, this showed significant progression of the far lateral L4/5 disc change with significant compression of the L4 nerve root. The L3 changes were unchanged. As a result, Ms Shanahan underwent a 2-level far lateral microdiscectomy at L3/4 and L4/5 on 16/1/19. She was discharged from Wollongong Hospital the day after the operation with resolution of her radicular symptoms down the right leg."

1. In a report to Ms Shanahan's general practitioner, A/Prof Jaeger said that "intra operatively, it appeared that the L4/5 disc fragment was the troublemaker" for the exacerbation of pain in 2018.
2. Ms Shanahan saw Dr Davies, neurosurgeon, at the request of her former solicitors for an assessment of permanent impairment in 2020. He recorded that Ms Shanahan's employment was terminated by IRT in July 2019 and that she then found work as an in-home carer with Uniting Care. Dr Davies assessed 13% whole person impairment (WPI).
3. Ms Shanahan did not claim permanent impairment compensation until 2022. IRT's insurer asked her to see Dr Bentivoglio, neurosurgeon, who recorded that Ms Shanahan changed jobs again in September 2021. At the time of his consultation, she was working 30 hours per week and had been doing so since September 2022, but was not required to do cleaning or repetitive bending. He assessed 14% WPI as a result of L3/4 and L4/5 disc injuries.
4. On 18 January 2023 Ms Shanahan signed a complying agreement, accepting compensation for 14% WPI.
5. When Ms Shanahan changed jobs in 2022 she started working for All Care Health Services Group Pty Ltd (All Care). On 16 September 2022 while working All Care, Ms Shanahan tripped and fell in a client's driveway.
6. Ms Shanahan saw A/Prof Jaeger who considered that she suffered "a left cranially herniated L4/5 disc herniation with compression of the L4 and L5 nerve roots". He performed further surgery on 6 April 2023 being a let L4/5 mediolateral microdiscectomy.
7. Ms Shanahan's solicitors sought an assessment of permanent impairment from Dr Mastroianni, occupational physician, who assessed 17% WPI.
8. Ms Shanahan seeks a finding that her permanent impairment exceeds the threshold to claim work injury damages from IRT. She argues that IRT is responsible for the whole of the WPI she now suffers. IRT argues that the 2022 injury in other employment was a new injury. That is the issue for determination.

PROCEDURE BEFORE THE PERSONAL INJURY COMMISSION

1. Two sets of proceedings between Ms Shanahan and IRT are currently on foot. In these proceedings, she sought referral to a Medical Assessor in respect of a threshold dispute for work injury damages. In 4011/25 she claimed permanent impairment compensation but she did not pursue that claim, pending the outcome of these proceedings.
2. At a preliminary conference on 22 May 2025, the parties agreed that Ms Shanahan should be examined by a Medical Assessor. If her WPI was less than 15%, there was no utility in maintaining either set of proceedings.
3. Ms Shanahan was examined by a Medical Assessor Crocker who issued a Medical Assessment Certificate (MAC) on 31 July 2025 in which he assessed 17% WPI.
4. This matter was listed for conciliation conference and arbitration hearing on 19 September 2025 when Mr Andrew Parker of counsel appeared for Ms Shanahan and Ms Grotte of counsel appeared for IRT.
5. I am satisfied that the parties to the dispute understand the nature of the application and the legal implications of any assertion made in the information supplied. I used my best endeavours in attempting to bring the parties to the dispute to a settlement acceptable to all of them. I am satisfied that the parties have had sufficient opportunity to explore settlement and that they have been unable to reach an agreed resolution of the dispute.

1. The following documents were in evidence before the Commission and considered in making this determination:

(a) Application for Assessment by a Medical Assessor and attached documents;

(b) Response, and

(c) MAC dated 31 July 2025.

1. There was no oral evidence.
2. Ms Shanahan's statements are concise. There is considerable medical evidence in the file. IRT's reply contains extensive extracts from the insurer's file in respect of the injury in the employ of All Care.
3. Counsel's submissions focussed addressed on a limited range of evidence. Rather than summarise all of the evidence in the file, I have set out the evidence to which I was taken in submissions below and referred to other relevant material when setting out my findings and reasons.

1. Ms Grotte addressed first. She said that Ms Shanahan had no entitlement to assessment in respect of a single impairment because she left IRT in January 2019 and worked for another employer before commencing with All Care. She was able to work for three years in pre-injury duties until she had another fall in September 2022, which was a separate and distinct injury. Ms Grotte said that IRT relied on the analysis in the report of Dr Walls, who saw Ms Shanahan at IRT's insurer's request.
2. To support IRT's argument, Ms Grotte took me first to the entry in the notes from RX Physiotherapy dated 26 September 2022. Ms Shanahan consulted a physiotherapist on that day and said that she "fell down a driveway whilst attending a client's home". Ms Shanahan presented with knee pain and associated bruising and pain with movement. She found loading her left leg was painful. The physiotherapist noted:

"Previous lower back surgery noted - good recovery, very compliant with rehab and regularly attends Pilates and strength training classes in order to manage her capacity. Had no pain prior to the fall."

1. Ms Grotte said that note was important because it described Ms Shanahan's situation immediately before she fell in the driveway. She said that the history that Ms Shanahan had no pain before the injury and the fact that she had been performing pre-injury duties, supported the contention that there was a new injury in September 2022.
2. Ms Grotte then took me to the referral from Ms Shanahan's general practitioner, Dr Simpson, to A/Prof Jaeger and said that the reference to a new disc protrusion. On 28 October 2022 Dr Simpson referred Ms Shanahan to Prof Jaeger and said:

"Thank you for seeing Carolynn Shanahan for an opinion and management of L4/5 disc protrusion with impinging of left L4 nerve root, Carolynn has radicular pain in the distribution of the left L4 nerve. This disc protrusion is new since her last scan in November 2021."

1. The scan to which Dr Simpson referred was an MRI dated 13 October 2022. The clinical history was:

"Numbness and tingling in left L4 distribution. Recent fail. Previous disc bulge L3/4. Previous left microdiscectomy L4/5 2019."

1. The radiologist noted that he was comparing the scan to one dated 22 November 2021. The finding at L4/5 was:

"At L4/5, annular fissure and a broad-based disc bulge with indentation of the thecal sac, No significant canal stenosis. There is a superimposed left paracentral disc extrusion measuring approximately 17mm in craniocaudal length. The disc extrusion has developed since the previous MRI dated 22/11/2021 and is orientated superiorly along the posterior margin of the L4 vertebral body with flattening and displacement of the descending Ieft L4 nerve root at the subarticular zone. There is mild to moderate left and mild right facet joint hypertrophy. Moderate left foraminal stenosis with contact of the exiting left L4 nerve root. Mild right foraminal stenosis."

1. Ms Grotte said that development of a disc extrusion supported the case that there was new pathology after September 2022. The previous scan did not show evidence of an extrusion but merely bulges. The report dated 22 November 2021 showed:

"Multilevel disc bulges and mild to moderate facet arthritis in the lumbar spine contributing to mild to moderate impingement of right L2, bilateral L3 and left L4 roots. No canal stenosis at any levels."

1. Ms Grotte said that Dr Walls, occupational physician, was provided with extensive documentation for the preparation of his reports dated 12 December 2024 and 3 February 2025, so that he cannot be criticised for not having the correct history. He set out the history of the first injury in 2011 and analysed the material leading up to the surgery in January 2019 being "L3/4, L4/5 microdiscectomy lumbar and rhizolysis." Dr Walls wrote:

"Today Caroline Shanahan reports that she improved over eight to nine months but was still suffering problems, she recalls lower back pain being present but less severe, she suffered occasional radiation to the left lower limb of pain and paraesthesia and believed that the strength in the left limb was less. There remained some impact on the activities of daily living and, as below, Carolynne continued to work with restrictions.

Between 2020 and 2022 Caroline became involved in community care again working 20 - 25 hours per week but avoiding cleaning activities."[1]

1. Ms Grotte said that the history Ms Shanahan provided was inconsistent with that recorded by the physiotherapist, which was that she was not receiving treatment from her treating specialist and was taking control of her own life by doing Pilates. Dr Walls noted that Ms Shanahan's general practitioner ordered a new scan, Dr Jaeger undertook further surgery on 6 April 2023 when Ms Shanahan said that a fragment was removed and:

"Today Caroline describes this second operation help but she still has lots of problems, her symptoms fluctuate, overall any improvement has ceased."

1. Recording Ms Shanahan's present symptoms, Dr Walls noted that low back pain was the biggest problem, radiating to the left lower limb and anterior border of the shin to the foot. He recorded a significant impact on Ms Shanahan's activities of daily living. Dr Walls noted that Ms Shanahan's leisure activities "prior to the back pain becoming intolerable" included dancing and walking. While conceding that Dr Walls did not identify when that was, Ms Grotte said it was presumably before 2022.
2. Dr Walls' diagnosis was "bilateral lumbar disc disease treated surgically on two occasions with a somewhat indifferent outcome." Ms Grotte said that statement was unclear because the first surgery resolved the disc protrusion and the impingement and that Ms Shanahan was able to get back to work, carry out her leisure activities and take control of her life but despite the second surgery, there were ongoing problems.
3. Dr Walls' diagnosis was:

"i. The diagnosis is Chronic Low Back Pain Syndrome secondary to bilevel lumbar disc disease.

1. There appears to have been two injury sequences, the initial L3/4 disc injury was complicated by a further injury at the disc below (L4/5) and then, as far as I can determine by separate incident (on an already damaged disc) in September 2022."

1. Asked if the injury in 2022 "represents a separate injury" to that in 2019, Dr Walls said:

"As far as I can determine the event of 16 September 2022 led to a new and separate injury, that is she had undergone a microdiscectomy at the L4/5 level but then proceeded to suffer a further disc protrusion at that level after the fall on 16 September 2022.

My reason for this is that the injury sustained in the course of her employment on 11 January 2019 had been addressed surgically with a good recovery and a return to work and the fall in September 2022 caused a further, 'new' disc protrusion."

1. Ms Grotte argued that Dr Walls said that the second injury was not an aggravation - a disc had extruded before, the extrusion was removed and there were no ongoing sequelae. The September 2022 injury was a separate and new injury. Asked to provide an assessment of permanent impairment, Dr Walls made an assessment in respect of the 2019 injury and then said:

"In my opinion Caroline then suffered a second discrete injury in September 2022 leading to a further/ recurrent disc protrusion at L4/5 requiring further surgery.

There is a WPI arising from that discrete injury but I am not of the opinion that this September 2022 injury can be aggregated to the effects of the 2011 injury although I would acknowledge some vulnerability (weakness) at the L4/5 level because of the prior injury/surgery.

My reasons for describing this as a discrete injury are:

• The force of the impact
• Carolynne's description of the severity of pain following this fall
• The different descriptions of the MRI scan of, namely of a 'left cranial herniated L4/5 disc herniation with compression of the L4 and L5 nerve roots as the culprit' and Carolynne's description of the removal of a 'fragment'."

1. Turning to Dr Mastroianni's opinion, Ms Grotte noted that his first report dated 2 May 2024 referred to only seven pieces of evidence so that his report can be criticised because it may not have been given in a fair climate. She said that the history is very short, referring to the injury in 2011, treatment over a period of years and surgery in 2019, after which Ms Shanahan managed her duties and domestic work but had to pace herself. Ms Grotte again stressed that was not consistent with the note of the physiotherapist. Ms Grotte described the history that Dr Mastroianni obtained as truncated and uninformative, and he did not examine, as Dr Walls did, the force of the fall in 2022. She observed that Dr Mastroianni did not examine the "critical" scan which postdated the 2019 surgery. Ms Grotte said that he conflated everything as a result of the injury in 2011, the nature and conditions of Ms Shanahan's work and the injury in 2022 to provide a "bold, bare ipse dixit" that:

"My diagnosis of the injuries sustained as a result of work at the Illawarra Retirement Trust is lumbar disc lesion and left leg sciatica for which he had two level discectomy.

In my opinion your client's employment with Illawarra Retirement trust was the main contributing factor to her developing the condition."

1. Ms Grotte said that Dr Mastroianni did not turn his mind to the actual issues that I am required to determine. His opinion that "the injuries involve damage to the same pathology, L4-5 disc lesion" did not take account of the 2021 MRI scan report.
2. Turning to Dr Mastroianni's second report dated 17 October 2024 for which he was asked to consider Ozcan v Macarthur Disability Services Ltd,[2] Ms Grotte said that Dr Mastroianni had not reviewed all of the relevant material when providing his opinion that:

"The claimant sustained an injury on 16 September 2022 on the background of a previous injury in 2011 for which she had surgery in January 2019.

Following the injury in 2022, symptoms persisted and she had further surgery by Dr Jager.

In assessing whole person impairment, I assessed the injury in 2022 as being an aggravation of a previous injury and not an isolated injury, unrelated to the previous condition.

In my opinion, the latter injury aggravated the pre-existing condition and resulted in part from the earlier injury."

1. Those reports were provided to Dr Walls who provided a supplementary report dated 3 February 2025 in which he explained that the injury in 2022 was not an aggravation because:

'i. The fall on 16 September 2022 was of some magnitude (that is capable of causing injury) accompanied by immediate and severe pain with Left radicular symptoms.

1. Prior to this fall and following the 'L3/4, L4/5 microdiscectomy, lumbar and rhizolysis' undertaken on the 16 January 2019 Carolyn Shanahan had been working as a Community Care worker working between 20 and 25 hours per week on restricted duties with some discomfort but not sufficient to keep her from that restricted work.
2. Carolyn consulted her treating surgeon, Dr Jaeger and his report of that time notes new pathology on an MRI scan stating 'A recent MRI of the lumbar spine from IRG showed a left cranial herniated L4/5 disc herniation with compression of the L4 and L5 nerve roots as the culprit'.

That is the previously identified 'Left L4/5 far lateral disc herniation' that was excised on 16 January 2019 had been supplanted by a new caudally oriented protrusion that was further excised on 6 April 2023, being the 'fragment' Carolyn describes and that this intervention was of some if incomplete assistance."

1. Dr Walls was asked if the 2022 injury "represents an exacerbation" of the 2019 injury or if he considered "some part of the subsequent damage would have been occasioned even if the original injury had not occurred", which Ms Grotte described generally as a reference to "the Oakley principles", referring to State Government Insurance Commission v Oakley[3] (Oakley). Dr Walls said that the 2022 injury did not exacerbate pre-existing pathologies and:

"I am not of the opinion that any subsequent damage would have been occasioned even if the original injury had not occurred. This was a specific event causing new pathology (in my opinion).

The previous bilevel injuries and surgery will have altered the anatomy and forces experienced by the lumbar spine.

There is surprisingly little good evidence about a person's increased vulnerability to further lumbar discal injury following an initial (and significant) disc injury.

I would accept accelerated facet joint arthrosis as a consequence of earlier injuries/surgical interventions but that is not Carolyn's problem.

A very old study from America Post suggested a 20% increased risk (of lumbar disc injury) above that faced by a person without that pre-existing history.

Therefore, I accept that Carolyn was at an increased risk (or increased vulnerability) of further lumbar disc injury but would rate this as low, in the order of 20 - 25% increased risk but this increase of risk was of low significance in the presence of the forces of impact associated with her unexpected fall (from which she wouldn't have had time to protect her landing)."

1. Ms Grotte submitted that opinion was sufficient and unequivocal support that Ms Shanahan suffered a discrete and separate injury and that Dr Walls had analysed all of the relevant material. She said that Dr Walls was asked questions about A/Prof Jaeger's opinion and other medical reports and said:

"I note that I did not examine Carolyn before her last surgical intervention in April 2023 and there was little in the way of reports detailing the results of any clinical examinations between September 2022 and April 2023.

These examination findings would not have been particularly informative (in my opinion), the [sic] would have confirmed a restricted range of motion, some Left lower limb sensory and possibly strength disturbance and perhaps disordered reflexes.

The key to diagnosis would have been the MRI scan +/- confirmation on surgical visualisation during the April 2023 surgery.

My conclusions were based on Carolyn's history, the MRI scan reports and her description of a "disc fragment".

1. Ms Grotte took me to the report of Dr Sheehy dated 20 February 2023. (The report shows that it was prepared for the management of a claim against All Care). Dr Sheehy said that Ms Shanahan suffered a series of injuries to other parts of her body which had resolved but that leg pain, which commenced following the fall and was associated with the L4/5 disc, had not resolved. Dr Sheehy was given A/Prof Jaeger's report dated 13 December 2022 and asked a series of questions. He said:

"Ms Shanahan has sustained a disruption of the L4/5 disc with compression of the L4 and L5 nerve roots as identified on the MR scan.

There is significant weakness in the knee extensors and a depressed knee jerk. She had been well following the surgery in 2019. It is the events of 16 September 2022 which have precipitated the discal injury. She became symptomatic within a day of the fall, with the development of leg pain and leg weakness."

1. Ms Grotte said that Dr Sheehy was asked if the injury was an aggravation and said:

"No, the aggravation is not so much an aggravation of her back condition as a direct injury to the L4/5 disc with disc disruption, compressing the L4 and L5 nerve roots. She is symptomatic with weakness of knee extension and a depressed knee jerk and persisting pain and she requires decompression of the L4 and L5 nerve roots, as outlined in Associate Professor Jaeger's letter."

1. Noting that Dr Moloney, neurosurgeon, had also provided a report, Ms Grotte said that it only dealt with incapacity.
2. In summary, Ms Grotte said that I would accept the report of Dr Walls, which was reasoned and extensive and considered all of the material to provide a rational basis for his opinion. She said that it should be contrasted with the report of Dr Mastroianni who "churned out a bare ipse dixit" without any real consideration of the MRI scan in 2021 taken about nine months before the fall. She said that there was enough evidence to find that there was a separate and distinct injury and that "there should not be a single impairment arising from the date of injury of 11 [sic] January 2019." Ms Grotte did not take me to any authority other than the brief references set out above.

1. Mr Parker began his submissions by saying that IRT's submissions failed to understand that the case is not simply about whether Ms Shanahan had a second injury. He said that what was conspicuously absent from IRT's submissions was any analysis of the issues set out in Oakley and Trustees of the Roman Catholic Church for the Diocese of Parramatta v Barnes[4] (Barnes). He said there was some limited analysis of the issues Department of Juvenile Justice v Edmed[5] (Edmed) to the extent that IRT claims there are separate pathologies. Mr Parker said that the case cannot be resolved merely by Dr Walls opinion. If it was merely a question of looking at medical opinion, Mr Parker said I am bound by the MAC.
2. Mr Parker provided Ms Grotte with a copy of the letter of instructions to Dr Mastroianni, which showed that he had been provided with the reports of Dr Jaeger and Dr Bentivoglio and the investigations but apparently not the MRI scan taken in 2021. That document was not provided to the Commission.
3. Mr Parker said the note from the physiotherapist dated 26 September 2022 should be read in context and it was not fair to say that the reference to Ms Shanahan having no pain immediately before the 2022 fall meant that she had no ongoing injury. In context, the note said that Ms Shanahan had made a good (not a complete) recovery and had ongoing problems which she managed by being compliant with rehabilitation and attending Pilates and strength training to manage her capacity. There was ample other evidence that Ms Shanahan continued to have back pain. Mr Parker said that IRT's case ignored both Ms Shanahan's evidence and the case law
4. In her statement, Ms Shanahan said that she understood that she had surgery to her lumbar spine at two levels, being L3-4 and L4-5. After the fall in September 2022, she said she had further problems in her lower back in the same area as she had experienced pain before. Mr Parker said that was not inconsistent with other histories she had given, including to Dr Walls in the passage set out at [29] above, where he recorded that Ms Shanahan improved but continued to suffer problems, with the back pain being present but less severe and that she continued to work with restrictions. He said that was not consistent with IRT's submission that Ms Shanahan was well and taking control of her own life.
5. Similarly, Mr Parker said that the Medical Assessor recorded in the MAC dated 31 July 2025 that Ms Shanahan told him that the surgery provided some symptomatic benefit. She did not provide a history that the pain was cured. Mr Parker said it would be unusual for someone who had agreed that she suffers 14% WPI would not suffer some ongoing symptoms. He said that I would not accept that the note from the physiotherapist established that Ms Shanahan was completely well.
6. Referring to the decision of Keating P in Palise v Australian and New Zealand Banking Group Limited,[6] Mr Parker said it was crucial to have regard to Ms Shanahan's evidence and failure to do so could lead to an error in the fact-finding process. Ms Shanahan's evidence confirmed that all of the issues she suffered after the second injury were in the same area as the first and the medical evidence established that she injured the same pathology so that I would find in her favour on the basis of Edmed.
7. Mr Parker said that the submission that Ms Shanahan suffered a new injury because there was a disc extrusion ignored what was said in Oakley and assumed that the extrusion could only have been caused by the fall. Mr Parker said that IRT had ignored case law with respect to causation and that "material contribution" was the relevant test. He said that Mr Edmed failed in his claim because he was seeking to "link up" multiple different body parts. On the contrary, Ms Shanahan argued that her claim involved the same pathology, bearing. In mind that she had surgery on the first occasion from L3/4 to L4/5 and that is how I should read Dr Mastroianni's opinion where he said:

"As a result of the incident in 2011, the nature and condition of her work and the subsequent incident in 2022, Ms Shanahan sustained lumbar disc protrusion causing back pain and left leg sciatica for which she had 2 operations. My clinical diagnosis is lumbar disc lesion and left leg radiculopathy."

1. Mr Parker said that would satisfy the criteria in both Edmed and Barnes to permit aggregation. Though the Medical Assessor was asked to assess Ms Shanahan in respect of the 2019 date of injury, he did not seek to separate the injuries. Mr Parker said that Dr Mastroianni's opinion in his second report supported the application of Oakley as discussed in Ozcan. Dr Mastroianni said:

"In my opinion, the latter injury aggravated the pre-existing condition and resulted in part from the earlier injury."

1. Turning to Dr Walls' report, Mr Parker said that his opinion did not support IRT's submission in that he said:

"A detailed history is given above, Caroline Shanahan developed low back pain in 2011 with a relatively innocuous stimulus.

This persisted, she underwent bilevel discectomy in 2019 and recovered reasonably well from that before suffering a fall in September 2022 leading to an L4/5 disc injury."

"In my opinion Caroline then suffered a second discrete injury in September 2022 leading to a further/recurrent disc protrusion at L4/5 requiring further surgery."

1. Mr Parker highlighted Dr Walls' use of "recurrent", which connoted that the second disc protrusion was associated with the earlier one. Mr Parker noted Dr Walls' statement that Ms Shanahan suffered a vulnerability or weakness at L4/5, which he said brought the claim within the first category in Oakley but it would probably also fall within the second, contrasting that position with IRT's submissions that proceeded on the basis that the 2022 injury was a novus actus interveniens, or the third category in Oakley. Mr Parker said it was impossible to find that the second injury was causally independent because the injuries were at the same level.
2. A/Prof Jaeger's report dated 6 January 2023 also did not support IRT's case, Mr Parker said. Asked if the MRI in December 2022 confirmed a new injury or an aggravation, A/Prof Jaeger said:

"This is difficult to determine with certainty. However, I consider it likely that the lower back injury from 2018 for which she had a left L3/4 and L4/5 far lateral microdiscectomy has progressed and is now causing the new mediolateral disc herniation.

As mentioned above, I consider this a reaggravation of the injury from 2018. The diagnosis is now that of a left cranially herniated mediolateral L4/5 disc herniation with compression of the L4/5 and L5 nerve roots."

1. The final question and answer in that report read:

"In consideration of your assessment, her medical history and the reported findings on the MRI, is the requested surgery recommended regardless of the incident at work on the 16/09/2022? Please clarify.

Apologies but I do not really understand this question fully. She had a work injury on 16th September leading to the above-mentioned disc herniation. Likely, this is a reaggravation of her previous work-related back injury. She has failed conservative treatment and hence my request for an operation."

1. Mr Parker said that Dr Sheehy's report also supported aggregation "in the Oakley sense" because the injury was at the same level which "does predispose to recurrent disc disruption.
2. In response to my question about the relevance of the opinion of Dr Bentivoglio, Mr Parker said that it supported Ms Shanahan's case because he said:

"I believe the original injury occurred on 28 September 2011 and has been running a relapsing and remitting course since that time} The original injury occurred while she was at work, and she has had several flare ups since that time caused by work injuries."

1. Mr Parker said that Ms Shanahan's case fell into either of the first and second categories in Oakley but not the third, which was IRT's case.

1. Ms Grotte said that I could certainly have regard to Ms Shanahan's statement but that the more compelling evidence was the contemporaneous material. Ms Shanahan saw Dr Moloney, neurosurgeon, who reported on 17 August 2023 and obtained a history of her work duties between the injuries and obtained a history of the injury in September 2022, after which she was no longer able to do her physical job. He said:

"Ms Shanahan informed me that in her past medical history, in 2011, she suffered an injury to her back during the course of her employment with the Illawarra Retirement Trust. She said that the incident came on during the course of her employment when she was cleaning a toilet and a disc lesion at L3/4 was diagnosed. She put up with the low back pain and intermittent leg pain for a long time and eventually saw A/Prof Jaeger in 2018. Further investigations revealed ongoing irritation at the L3/4 level and surgical intervention was carried out in 2018. She told me that she was happy with the result of the surgery and she endeavoured to have a return to work, however, IRT made her redundant and she left their employment and was then employed by Uniting for 2-1/2 to 3 years.

She, unfortunately, has not been able to return to work at All Care, though she has a certificate which indicates that she would be suitable for 10 hours of work per week with a lifting restriction of 3 kg which would make her suitable for office work or respite/social work in the community. Sometimes, there are clients who require just a call in and a cup of tea and biscuit to check how they are and whether there is anything that can be done by the organisation. Ms Shanahan told me that she uses her own car which is automatic and she is able to drive her car without difficulty. There should be a job in the All Care organisation which would fit her capabilities at this stage."

1. Turning again to Dr Sheehy's report, Ms Grotte said that I would accept his contemporaneous history that:

"Ms Shanahan gave a history that she fell on a client's driveway on 16 September 2022, with the development of left knee pain, right hand and wrist pain and left forearm grazing, which was noted by the GP on the day of the occurrence. The GP did note any leg symptoms, but she developed pain in the left knee, radiating to the foot within a day of this injury and a numbness in the shin area. The next day, she had a collapsing episode where the left knee gave way.

Prior to this injury, she had been mobilizing normally without any leg symptoms."

1. Ms Grotte said that the MAC was irrelevant because it did not deal with causation. She said that the 2022 injury fell squarely into the third category in Oakley because, as Dr Walls explained, Ms Shanahan fell with great force and the 2022 injury would have occurred whether or not she had suffered the original injury. Ms Grotte said that there was no element of aggravation. There were no symptoms before the second injury and, though Ms Shanahan may have suffered a weakness or vulnerability, that may be the same as anyone else. Ms Grotte said that the "problem" was eliminated by the previous surgery and Ms Shanahan was working
2. Ms Grotte sought to review the decision in Edmed and asked for leave to file a note dealing with it. I granted that leave and offered Mr Parker a right of reply.

1. Ms Grotte sought to review the decision in Edmed and asked for leave to file a note dealing with it. I granted that leave and offered Mr Parker a right of reply.
2. On behalf of IRT, Ms Grotte said that, in Edmed, Roche DP referred to s 322(2) of the Workplace Injury Management and Workers Compensation Act 1998 (the 1998 Act) which provides that impairments that result from the same injury are to be assessed together to assess the degree of permanent impairment. Roche DP held that the same injury meant the same pathology.
3. Ms Grotte said that the principle cannot apply to injuries sustained with two different employers because the employers have separate liabilities and because s 323 of the 1998 Act would have no work to do. She said that the injuries could only be aggregated if there was evidence of a material contribution to the second injury and that evidence of a vulnerability was insufficient.
4. In reply, Mr Parker observed that IRT's supplementary submissions were not supported by reference to authority. He said that Edmed was not distinguishable and that the impairments can be aggregated. In any event, Ms Shanahan's impairment is greater than 15% based on the statements in Barnes, Oakley and Ozcan.

1. IRT's submissions did not contain detailed references to authority and its case is that the 2022 injury in the employ of All Care fell into the third category set out in Oakley.
2. In Oakley in the Supreme Court of Western Australia Malcolm CJ set out three categories in which determination of the issue of causation requires consideration of the effect of a subsequent injury. The principles were applied in a workers compensation context in Secretary, New South Wales Department of Education v Johnson[7] (Johnson). Johnson was an appeal from an application for judicial review of a Medical Appeal Panel of the Workers Compensation Commission. Ms Johnson was employed by different employers at the time of her first and second injuries.
3. Setting out the principles, Simpson AJA said:[8]

"... the appellant invoked, and placed heavy reliance on, the decision of Malcolm CJ in State Government Insurance Commission v Oakley (1990) 10 MVR 570; [1990] Aust Torts Reports 81-003. In that case, the Chief Justice identified three categories where the issue of causation involves consideration of the effect or impact of a subsequent injury on the determination of the cause of an earlier injury (or, perhaps more accurately, the assessment of damages consequential upon an earlier injury). The observations were made in the context of proceedings at common law in which negligence is alleged, but are equally applicable to the assessment of the degree of permanent impairment resulting from injury under no-fault legislation such as the WC Act. His Honour identified the three categories as:

'(1) where the further injury results from a subsequent accident, which would not have occurred had the plaintiff not been in the physical condition caused by the defendant's negligence, the added damage should be treated as caused by that negligence;

(2) where the further injury results from a subsequent accident, which would have occurred had the plaintiff been in normal health, but the damage sustained is greater because of aggravation of the earlier injury, the additional damage resulting from the aggravated injury should be treated as caused by the defendant's negligence; and

(3) where the further injury results from a subsequent accident which would have occurred had the plaintiff been in normal health and the damage sustained include no element of aggravation of the earlier injury, the subsequent accident and further injury should be regarded as causally independent of the first.' "

1. In Johnson, Emmett AJA, with whom Macfarlane JA agreed, said:[9]

"In common law contexts, an injury or incapacity may be attributable, in the legal sense, to more than one cause operating concurrently. [See Baker v Willoughby [1969] UKHL 8; [1970] AC 467 at 492.] There is no difference between the legal view of causation in tort and causation in the field of workers compensation, subject to the qualification that, in a claim for workers compensation, it is unnecessary to prove that the incapacity was the natural and probable consequence of the injury. That is to say, the question of foreseeability does not arise. It is sufficient that the incapacity results from the injury by a chain of legal causation unbroken by a novus actus interveniens. [See Busby v Morris [1980] 1 NSWLR 81 at [19].]

Two causation tests are involved in a medical assessment of permanent impairment under Pt 7 of Ch 7 of the Management Act. The first test arises from the provisions of ss 9 and 9A of Compensation Act. That is to say, it must be shown that the injury that gave rise to the impairment in question arose out of or in the course of employment that and that the employment was a substantial contributing factor to the injury. The second test arises from the provisions of ss 319(c) and 326(1)(a) of the Management Act. That is to say, it must be shown that the permanent impairment is as a result of the injury.

The phrase 'the degree of permanent impairment of the person as a result of an injury' appears in both ss 319(c) and s 326(1)(a) of the Management Act. That composite phrase requires an enquiry as to the causal connection between the degree, or percentage, of assessed permanent impairment of a worker, on the one hand, and the compensable injury, on the other. That is to say, it was necessary for the AMS and the Appeal Panel to assess the degree, or percentage, of whole person impairment of the Worker that was caused by or is attributable to the First Injury. In doing so, common law principles of causation in tort are to be applied.' "

1. The principles were applied in Ozcan v Macarthur Disability Services Ltd.[10] Ms Ozcan had suffered an injury in 2011 to her lumbar spine, thoracic spine and right shoulder. She suffered two further injuries to her lumbar spine and thoracic spine in 2012. A Presidential Member of the Workers Compensation Commission held that the right shoulder injury did not materially contribute to the impairments to the lumbar and thoracic spine and was not the same pathology so that it could not be assessed with those injuries. Macfarlane JA said:[11]

"First, Ms Ozcan submitted that the Deputy President was correct to add the WPI percentages referable to the thoracic and lumbar spine injuries suffered in the second and third incidents to those suffered in the first incident because those subsequent injuries were materially contributed to by the spinal injuries suffered in the first incident. As the Deputy President held (at [129]-[130]), this causal connection placed the injuries in the second category described in State Government Insurance Commission v Oakley (1990) 10 MVR 570 at 573. That second category was identified in Oakley as one 'where the further injury results from a subsequent accident, which would have occurred had the plaintiff been in normal health, but the damage sustained is greater because of aggravation of the earlier injury [with the result that] the additional damage resulting from the aggravated injury should be treated as caused by the defendant's negligence'(at 573). This approach is simply an application of s 65(1) of the 1987 Act that describes the degree of permanent impairment for which compensation is payable as that which 'results' from the injury in question and s 65(2) which requires injuries 'arising out of the same incident ... to be treated as one injury ...'.

Secondly Ms Ozcan argued that, in these circumstances, it was clear that both the right shoulder injury and the thoracic and lumbar spinal injuries 'resulted from' and 'arose out of' the first incident: the first spinal injuries and the shoulder injury admittedly did so and the effect of the first step in Ms Ozcan's argument ... was that the spinal injuries suffered in the second and third incidents also did so. In consequence, they should all have been "treated as one injury" and "assessed together", as directed by s 65(2) of the 1987 Act and s 322(3) of the 1998 Act, leading to a 15% WPI finding.

The Deputy President reached a different conclusion because she found that the right shoulder injury 'did not materially contribute to the impairments of the lumbar or thoracic spine and was not the same injury (pathology)' (see [145] and [150] quoted in [11] above). This was not however, with respect, the issue that needed to be addressed. The relevant question was whether the later spinal injuries resulted from those suffered on the first date. If they did, s 322(3) of the 1998 Act required them to be assessed with the impairment arising out of the right shoulder injury because the injuries all arose out of the same incident, that is, that of 14 November 2011."

1. In Ozcan the Court of Appeal distinguished Edmed. Macfarlane JA said:[12]

"It is not however necessary, or indeed appropriate, to express any concluded view concerning the correctness of the decision in Edmed. Ms Ozcan did not assert that it was incorrect but, for good reason, submitted that it was not, even if correct, determinative of the presently proposed appeal. Edmed is distinguishable from the present case at least for the reason that Roche DP did not address any argument, presumably because none was put to him, that the first wrist injury with which that case was concerned materially contributed to the second. There thus did not arise in that case any suggestion that the second injury 'arose out of 'or 'resulted from' the first. The decision did not therefore contradict what I consider to be the correct conclusion in the present case that, because the first spinal injuries contributed to the later ones, the impairments 'resulting from' the later injuries, as with those 'resulting from' the first, 'arose out of' the incident in which the first were suffered, thereby attracting s 65(2) of the 1987 Act and s 322(3) of the 1998 Act."

1. The case presented by IRT is unusual because its insurer relies on the evidence obtained to manage and defend Ms Shanahan's claim against it in respect of the injuries deemed to have been suffered in 2019 as well as on the evidence obtained to manage Ms Shanahan's claim in respect of the 2022 injury in the employ of All Care. I was taken to a series of isolated references which did not focus on the context in which the documents were prepared.
2. A high point of IRT's case was its construction of a note made by a physiotherapist on 26 September 2022, days after the 2022 injury. I do not agree that the note should be read as Ms Grotte submitted, to the effect that Ms Shanahan was taking control of her life and not under specialist treatment at the time of the injury.
3. In Davis v Council of the City of Wagga Wagga[13] Mason P, with whom the other members of the Court of Appeal agreed, said that "experience teaches that busy doctors sometimes misunderstand or misrecord histories of accidents, particularly in circumstances where their concern is with the treatment or impact of an indisputable, frank injury". In Nominal Defendant v Clancy[14] Santow JA said:

"While clinical notes, as McColl JA observes, may in common experience be the raw data on which diagnosis and opinions are based, it does not follow that they will be comprehensive ... clinical notes are written in the course of a busy practice where the clinician is primarily there to observe and administer treatment. They should not be construed with the minute attention one might give a formal legal document. It is fair to say a report to another doctor [or a medico-legal report] is likely to have been written with more deliberate consideration than rough notes."

1. In Mason v Demasi[15] Basten JA said:

"First, the trial judge was invited to discount the appellant's oral testimony on the basis of accounts given to various health professionals, which appeared inconsistent either with each other, or with her oral testimony, or both. The difficulties attending this kind of exercise should be well-understood; as explained in the Container Terminals Australia Ltd v Huseyin [2008] NSWCA 320 at [8], such apparent inconsistencies may, and often should, be approached with caution for the following reasons, amongst others:

(a) the health professional who took the history has not been cross-examined about:

(i) the circumstances of the consultation;

(ii) the manner in which the history was obtained;

(iii) the period of time devoted to that exercise, and

(iv) the accuracy of the recording;

(b) the fact that the history was probably taken in furtherance of a purpose which differed from the forensic exercise in the course of which it was being deployed in the proceedings;

(c) the record did not identify any questions which may have elucidated replies;

(d) the record is likely to be a summary prepared by the health professional, rather than a verbatim recording, and

(e) a range of factors, including fluency in English, the professional's knowledge of the background circumstances of the incident and the patient's understanding of the purpose of the questioning, which will each affect the content of the history."[16]

1. The physiotherapist noted that Ms Shanahan had a good recovery from previous surgery. They also recorded under the hearing "Red flags":

"Pt fell onto her stomach and hurt left leg

Pt reports that she has pain down her left leg in the dermatomal pattern of L3-5"

1. As I understand its usage in medical records, a red flag is a reference to a symptom which may have significant consequences.
2. The physiotherapist noted that Ms Shanahan had made a good recovery prior to the recent fall and that she attended Pilates and strength training to manager her capacity. In the context of the things the physiotherapist had recorded, the reference to "no pain prior to the fall" could give rise to a number of interpretations, including no pain generally, no pain on the day of the fall or no pain which caused her to fall. Based on the authority set out above, I do not agree that it necessarily carries the inference that IRT sought to draw.

1. IRT also relied on the findings on the 2022 MRI scan and the general practitioner's referral form, referring to a new disc protrusion since a scan in 2021. A/Prof Jaeger's treatment of Ms Shanahan should be seen in context.
2. Ms Shanahan first saw A/Prof Jaeger on 13 March 2018 with a long history of lower back problems with left sided sciatica, which started in 2011. Six months before the consultation, she developed left sided paraesthesia in her leg. A/Prof Jaeger saw Ms Shanahan regularly until the surgery on 16 January 2019. He anticipated that the surgery would be at L3/4 but the MRI scan taken on the day before surgery showed that the L4/5 disc was also involved and he performed a microdiscectomy at that level also.
3. Ms Shanahan saw A/Prof Jaeger in September 2019 when she suffered some right sided back and leg pain in August 2019. A/Prof Jaeger recommended regular core-strengthening exercises to minimise the risk of recurrent issues. He said:

"I have again reiterated to Carolynn that she needs to do regular core strengthening exercise to minimise the risk of recurrent issues in the future. Unfortunately, she tells me that she has not done much more than regular walking since her surgery. She should continue with her current physiotherapy, but also needs to commit to regular gym attendances, pilates classes or core exercise classes in the future."

1. On 1 November 2021 Dr Stevenson referred Ms Shanahan back to A/Prof Jaeger for "management of evolving backpain". Dr Stevenson wrote:

"Carolyn reports back pain and spasm and at the site, she struggles to sit or stand for any length of time and is keen to be seen by yourself-app provided for 6th December 2021. I wonder whether you would consider providing a referral for an MRI prior to her appointment."

1. Ms Shanahan then underwent the MRI scan dated 22 November 2021. IRT relied on the report but did not take me in submissions to the circumstances under which it was obtained. A/Prof Jaeger said in his report dated 6 December 2021:

"Carolyn now reports that around mid-October, she developed very severe left leg pain. This was most likely of a radicular nature and was mainly in an L3 distribution as per her description. Importantly, with an expectant conservative approach, with analgesia, it appears as though her symptoms have fully settled and Carolyn was not in any pain today. She remains on Palexia 100mg nocte.

...

MRI of the lumbar spine from IRG showed evidence of the previous operation at L3/4 and L4/5 on the left side. There was no clear significant abnormality to explain her symptoms.

I discussed with Carolyn that it sounds like she had a temporary episode of L3 pain in the left leg which has essentially settled with a conservative approach. I have advised her to reduce the Palexia and take 50mg SR nocte for a few days and then stop altogether. It is unlikely that her pain will flare with a reduced dose in her analgesia."

1. Ms Shanahan next saw A/Prof Jaeger after the injury in September 2022. While he had not seen her for some time, his reports do not support IRT's contention that Ms Shanahan was pain free and taking control of her life in the period leading up to the second surgery. The steps Ms Shanahan had taken to control her symptoms had been taken at A/Prof Jaeger's suggestion.
2. On 6 January 2023 A/Prof Jaeger informed IRT's insurer, as set out above, that he considered that the "lower back injury from 2018 for which she had a left L3/4 and L4/5 far lateral microdiscectomy has progressed and is now causing the new mediolateral disc herniation".
3. A/Prof Jaeger expressed that opinion having ordered the 2021 MRI scan and reviewed it at the time of the previous consultation and having reviewed the comparison report prepared in 2022. IRT stressed the comment by Ms Shanahan 's general practitioner in her referral that the disc protrusion was new but it not persuasive in light of A/Prof Jaeger's opinion.
4. In his report to the general practitioner dated 1 May 2023 A/Prof Jaeger described the second operation as being for treatment of "refractory" left L5 radicular pain.
5. I take from those reports that A/Prof Jaeger was satisfied that the second injury was a progression of the condition that caused the first.

1. Ms Shanahan was examined by three other neurologists, either for IRT's insurer or that of All Care.
2. Dr Bentivoglio saw Ms Shanahan and reported to IRT's solicitor on 19 November 2022. The report does not indicate the purpose of the consultation, though he was asked to prepare an assessment of WPI as a result of the 2019 injury. He recorded a detailed history of the injury with IRT dating back to 2011. He did not have a history of the 2022 injury but did record that her duties had changed in September 2022.
3. Dr Bentivoglio recorded that after the 2019 surgery:

"Since the surgery there has been significant improvement in the low back pain and the left leg pain and overall, there has been a 40-50% improvement. She had physiotherapy post-operatively for about two months and did not get back to her original work and, if anything, she was made redundant."

1. After setting out his examination findings, Dr Bentivoglio said:

"My working diagnosis is a lady with discogenic low back pain from L3/4 and L4/5 disc injuries with mild persistent neuropathic pain in the left leg and mild radiculopathy. Her current treatment is doing Pilates when she works as a carer and she is seeing a psychologist who she has seen for the last two years, which she finds very helpful."

"I believe her employment is the main contributing factor for her to develop the disc injury at the L3/4 and L4/5 levels. She did not have any prior back issues before that, so I believe these are acute disc problems.

I believe the original injury occurred on 28 September 2011 and has been running a relapsing and remitting course since that time. The original injury occurred while she was at work, and she has had several flare ups since that time caused by work injuries."

1. While Dr Bentivoglio did not have a history of the 2022 injury, his report is relevant because it does not support IRT's argument that Ms Shanahan was pain free before the 2022 injury.
2. Dr Sheehy's report appears in the IRT's index under the heading "Claim Number - 5098678" and notes Ms Shanahan was employed by All Care. He obtained the history that Ms Shanahan had a good recovery with relief of back and leg symptoms and that there were no symptoms affecting her back and leg while working for All Care.
3. Dr Sheehy was asked a series of "specific questions" by All Care's insurer. The insurer asked Dr Sheehy to:

"...Please clarify if she sustained a new injury or an aggravation to her back from the reported incident at work on the 16/09/2022 or whether her presenting symptoms are a progression of her previous back condition since 2018 regardless of the reported incident at work? If this cannot be determined, please advise what information you require to assist with this."

"She has had a previous back injury in 2011, when cleaning a toilet. She initially experienced low back pain and subsequently left leg pain in 2014 and in 2018 she had pins and needles in the left leg, precipitating an operation for disc disruption at the L3/4 and L4/S levels on the left on 16 January 2019. She had a good recovery and after three months, she returned to work, with no persisting symptoms in the back or leg until the fall occurring on 16 September 2022. There had been previous surgery at the L4/5 level which does predispose to recurrent disc disruption. She had been well following the surgery in 2019 and this is a new event, which has occurred at the L4/5 level on the left and is not a progression of her previous back condition and is a new injury."

1. Asked if there was "an aggravation to her back from the reported incident on the 16/09/2022" and whether the aggravation had now ceased, Dr Sheehy expressed the opinion to which Ms Grotte took me, set out at [43] above. Dr Sheehy considered that the proposed surgery was necessary.
2. Dr Moloney saw Ms Shanahan on behalf of All Care and reported on 17 August 2023. As Ms Grotte said, the examination took place to assess Ms Shanahan's capacity for work. Dr Moloney recorded a history of the 2011 injury and said Ms Shanahan put up with the pain until she saw A/Prof Jaeger in 2018. He also assumed that the first surgery was at L3/4 and the second at L4/5. Dr Moloney said that Ms Shanahan required neurophysiological investigations to ascertain if there is ongoing L4 radiculopathy and said that spinal fusion may be necessary.
3. The value of each of those reports for present purposes is limited because each was obtained to respond a specific claim and the information which was provided appears to have been limited. Relevantly, Dr Bentivoglio's opinion does not support the contention that Ms Shanahan was pain free in the period leading up to the 2022 injury. Dr Sheehy pointed out that previous surgery does predispose to recurrent disc disruption.

1. In these proceedings, each party relied on the report of an occupational physician rather than a neurosurgeon.
2. Dr Mastroianni had a history consistent with that set out in A/Prof Jaeger's reports and that of Dr Bentivoglio - that Ms Shanahan had ongoing symptoms. His first report was prepared for an assessment of WPI and he did not engage with the issues which I am required to determine. He said, however, that the two injuries involved damage to the same pathology. In his second report, having considered material relating to the decision in Ozcan, Dr Mastroianni said that the second injury was an aggravation of the first and resulted from it.
3. IRT relied on reports from Dr Walls. Like Dr Bentivoglio, he recorded that Ms Shanahan had ongoing symptoms after the 2019 surgery. When answering the questions asked of him, Dr Walls said that Ms Shanahan recovered "reasonably well."
4. The following question and answer appear in Dr Walls' first report:

"Please provide your opinion as to whether you consider the injury the claimant sustained on 16 September 2022 represents a separate injury to that sustained during the course of her employment on 11 January 2019. Please also provide reasoning for your opinion.

• As far as I can determine the event of 16 September 2022 led to a new and separate injury, that is she had undergone a microdiscectomy at the L4/5 level but then proceeded to suffer a further disc protrusion at that level after the fall on 16 September 2022.
• My reason for this is that the injury sustained in the course of her employment on 11 January 2019 had been addressed surgically with a good recovery and a return to work and the fall in September 2022 caused a further, 'new' disc protrusion."

1. Dr Walls was not guided by that question, and subsequent questions, to the fact that injury can mean the pathology or the injurious event.[17]
2. There is no dispute that Ms Shanahan suffered two injurious events or that there was additional pathology in 2022. He was not asked to consider at that time if the second injury was an aggravation of the first. Rather than providing guidance as to how the question of aggravation should be addressed, Dr Walls was asked to assess permanent impairment and:

"We ask that you kindly provide your opinion with respect to apportionment if you consider that the incidents in 2007, 2020 and 2021 constituted a new injury. We kindly request you provide your opinion as to whether the assessments of whole person impairment for the injury in deemed to have occurred in 2019, and the injury sustained in September 2022 can be aggregated."

1. As part of his answer to that question, Dr Walls gave the answer set out at [35] above. In that answer, Dr Walls acknowledged a vulnerability. He then went on to give reasons being the force of the impact, Ms Shanahan's description of the pain and the different descriptions on the MRI scan.
2. In his second report, Dr Walls answered further questions, none of which adequately directed him to the issue to be determined. He was asked:

"Please provide your opinion as to whether the injury the claimant sustained on 16 September 2022 represents an exacerbation of the injury she sustained with a deemed date of 11 January 2019. Alternatively, do you consider some part of the subsequent damage would have been occasioned even if the original injury had not occurred. We kindly request you provide your reasoning for your opinion with reference to the available medical evidence and your findings on examination."

1. Dr Walls gave the answer at [40] above, the elements of which are contradictory. He said that he did not consider that the fall exacerbated pre-existing pathologies but that the previous injury and surgery altered "the anatomy and forces experienced by the lumbar spine." He then quoted an old study, without detailed attribution, suggesting a 20% increased risk of lumbar disc injury. He accepted that Ms Shanahan was at increased risk but rated the risk as low, in the context of an unexpected fall.
2. Dr Walls was then provided with a series of assumptions based on A/Prof Jaeger's reports and other evidence to which Ms Grotte took me in submissions being the two changes of employment after the first surgery, the 2021 MRI scan, the 2022 injury and the terms of Dr Simpson's referral and A/Prof Jaeger's diagnosis and surgery. Dr Walls was asked to "indicate the findings on examination" that Ms Shanahan suffered a new disc protrusion. Dr Walls said that the examination findings would not have been informative but:

"The key to diagnosis would have been the MRI scan +/- confirmation on surgical visualisation during the April 2023 surgery.

My conclusions were based on Carolyn's history, the MRI scan reports and her description of a 'disc fragment'."

1. Neither Dr Mastroianni nor Dr Walls engages precisely with the categories set out in Oakley but neither was asked a clear and concise set of questions. Dr Mastroianni was provided with some undisclosed material that directed him to consider the decision in Ozcan. His opinion that the second injury aggravated the previous condition and resulted in part from it is a paraphrase of the first category. He did not provide detailed reasoning.
2. Dr Walls was not asked to engage with the three categories but was provided with a long series of somewhat confusing assumptions. His opinion can be best be distilled to the statement in [113] above.

1. Ms Shanahan has undergone surgery on her L3/4 and L4/5 discs in both 2019 and 2022. Both of those operations were carried out by A/Prof Jaeger. Taking into account Dr Walls' statement that the key to diagnosis was the MRI scan and visualisation during surgery, I consider that A/Prof Jaeger's opinion is the most useful for determining the question of whether IRT is responsible for the consequences of the subsequent injury.
2. A/Prof Jaeger's opinion was succinctly expressed but was given in response to a direct question. He considered that the original injury had progressed to a L4/5 herniation in 2022.
3. There is limited evidence about the force with which Ms Shanahan fell. Ms Shanahan did not describe it to any degree in her statement. The certificate of capacity signed by Dr Fernandez on 20 September 2022 said that Ms Shanahan "fell on client's driveway from standing height with impact to both knee (particularly L) and both wrists/forearms". The reference to standing height connotes a significant fall.
4. Though there is evidence of recurring complaints between 2019 and 2022, I accept that the 2022 injury involved significant force and Ms Shanahan suffered other abrasions and bruising as well as the progression of the injury to her back. In those circumstances, I consider that A/Prof Jaeger's opinion supports the conclusion that the 2022 injury falls into the second category in Oakley - that the further injury results from a subsequent accident, which would have occurred had the plaintiff been in normal health, but the damage sustained is greater because of aggravation of the earlier injury.
5. I therefore find, in accordance with the MAC, that Ms Shanahan suffers 17% WPI as a result of the injury suffered in the employ of IRT which is deemed to have occurred on 16 January 2019. Because Ms Shanahan sought only a determination that her WPI exceeded the threshold for a claim for work injury damages, I make no order.

[1] Dr Walls' reports contain several different spellings of Ms Shanahan's given name.

[2] [2021] NSWCA 56.

[3] (1990) 10 MVR 570.

[4] [2015] NSWWCCPD 35.

[5] [2008] NSWWCCPD 6.

[6] [2018] NSWWCCPD 13 at [89]- [90].

[7] [2019] NSWCA 321.

[10] [2021] NSWCA 56.

[13] [2004] NSWCA 34 at [35].

[14] [2007] NSWCA 349.

[15] [2009] NSWCA 227.

[17] Lyons v Master Builders Association of NSW (2003) 25 NSWCCR 423