Houting v State of NSW (Forestry Corporation of NSW)
[2023] NSWPICMP 580
•11 October 2023
| DETERMINATION OF APPEAL PANEL | |
| CITATION: | Houting v State of NSW (Forestry Corporation of NSW) [2023] NSWPICMP 580 |
| APPELLANT: | John Houting |
| RESPONDENT: | State of New South Wales (Forestry Corporation of NSW) |
| APPEAL PANEL | |
| MEMBER: | Richard J Perrignon |
| MEDICAL ASSESSOR: | James Bodel |
| MEDICAL ASSESSOR: | David Crocker |
| DATE OF DECISION: | 11 October 2023 |
| CATCHWORDS: | WORKERS COMPENSATION - Appeal from assessment of whole person impairment (lumbar spine); whether assessor erred in deducting 4/5ths for pre-existing injury and fusion at L5/S1; Held – Medical Assessment Certificate revoked and replaced. |
BACKGROUND TO THE APPLICATION TO APPEAL
The appellant worker, Mr Houting, appeals from the Medical Assessment Certificate of Medical Assessor Anderson dated 17 April 2023.
Medical Assessor Anderson assessed a 6% whole person impairment (5% lumbar spine, 1% scarring) as a result of injury on 7 August 2020, when the worker injured his L4/L5 disc while moving a rock in order to unload gravel from a tipper truck. Medical Assessor Anderson assessed 25% whole person impairment in respect of the lumbar spine, from which he deducted four fifths (or 20% whole person impairment) for the effects of a previous injury at L5/S1 on 15 August 2012.
The appellant submits that the Medical Assessor erred in making that deduction.
The Appeal Panel conducted a preliminary review of the Medical Assessment Certificate in the absence of the parties and in accordance with the NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment (4th edition) (the Guidelines).
Submissions
The parties made written submissions which have been taken into account. They are not repeated in full, but are summarised briefly below.
The appellant worker submits as follows:
(a) On 15 August 2012, the appellant jarred his neck and lower back at work, causing left leg pain. On 4 June 2013 he came to L5/S1 decompression surgery at the hands of neurosurgeon Dr Ow-Yang, with bilateral rhyzolysis and interbody fusion with pedicle screw at L5/S1. By 2014 the leg symptoms had resolved (as reported by insurer’s independent medical expert (IME) Dr Powell on 19 February 2014) so that he had been able to return to full-time work, with an expectation that he would return to pre-injury duties after his gym program. A complying agreement dated April 2014 provided for 18% whole person impairment, in accordance with the assessment of orthopaedic surgeon Dr Powell dated 24 February 2014. Despite work injuries on 3 May 2018 and 25 October 2018, by the time of his injury on 7 August 2020, the appellant had returned to pre-injury duties on a full-time basis, with overtime. He experienced back pain from time to time, which would resolve with rest and analgesics. On 19 April 2021 he again came to surgery at the hands of
Dr Ow-Yang, this time for an L4/5 laminectomy and microdiscectomy with rhyzolysis, with posterior interbody fusion from L4 to S1 plus revision of the previous L5/S1 pedicle screw.(b) The Medical Assessor “tried to subtract an amount of WPI [whole person impairment] based on an old assessment” and “wrongly failed to consider the proportion of pre-existing impairment to be deducted in the circumstances”. It is impermissible to deduct the whole person impairment found in respect of a previous injury from the whole person impairment found in respect of an injury: Bluescope Steel Limited v Halloran [2023] NSWPICMP 36.
(c) The Medical Assessor made an assumption about the effect of the earlier surgery without identifying the appropriate proportion to be deducted, contrary to the principles in Cole v Wenaline [2010] NSWSC 78.
(d) In doing so, he failed to consider, or placed too little weight on, relevant evidence suggesting that the extent of the deduction was difficult or costly to determine, namely the statement of the worker that he had returned to full duties on a full time basis plus overtime prior to injury, interrupted by temporary flare ups.
State of New South Wales (Forestry Corporation of NSW) (the respondent) submits as follows.
(a) Dr Mastroianni, on whose assessment the worker relied, deducted one fifth for the effect of injury on 27 August 2012, as a disc (at L4/5) above a fusion (at L5/S1) is susceptible to injury.
(b) Dr Machart deducted one half, as the pathology at L4/5 was symptomatic prior to injury on 7 August 2020, and the L5/S1 fusion contributed to the pathology at L4/5 in the form an adjacent level disease.
(c) Medical Assessor Anderson deducted 20% (or 4/5ths) whole person impairment, as that figure had been assessed by Dr Powell in 2014, after the L5/S1 fusion and prior to injury in August 2020.
(d) Dr Powell, Dr Machart and Dr Mastroianni all considered that the fusion surgery in June 2013 contributed to the pathology at L4/5.
(e) Medical Assessor Anderson did not simply assume that injury on 27 August 2012 contributed to the current level of impairment.
(f) There is no medical evidence as to the state of the lumbar spine at L4/5 immediately prior to injury on 7 August 2020, or in the years from November 2013 to August 2020.
(g) Medical Assessor Anderson expressly took into account the statement of the appellant.
(h) He provided detailed reasoning for deducting 4/5ths. That deduction was reasonably open to him.
(i) A deduction of at least half is appropriate if the Medical Assessment Certificate is set aside.
Deduction for pre-existing injury
At [10b], the Medical Assessor explained his calculations as follows:
“There has been a spinal fusion which automatically places Mr Houting into DRE Lumbar Category IV. This provides a whole person impairment ranging between 20% and 23%, depending on the activities of daily living. For this he would qualify with a further 2%, giving 22%.
There has been previous surgery to his lumbar spine in June 2013. On that occasion there was a fusion at L5/S1. On this occasion, the fusion was extended to include L4/5. Although it has been described that the revision at the L5/S1 articulation was a ‘technical issue’ in order to facilitate the extension to include L4/5, it is still a fact that there has been surgery to both levels. It is therefore interpreted that this qualifies for an additional 1% for second level surgery according to the SIRA Guidelines Page 29, Table 4.2. There is also continuing radiculopathy down the left leg, which qualifies for a further 3% from the same table. These two figures are combined, giving 4%. This is further combined with the earlier 23%, which therefore gives Mr Houting a whole person impairment of 25%.
In summary, he assessed a Diagnosis Related Estimate (DRE) category IV impairment due to successful fusion surgery at L4/5. This produced a base assessment of 20%, in accordance with Table 15.3 of the American Medical Association Guides to the Evaluation of Permanent Impairment (5th edition) (AMA5). To this, he added 2% for effects on activities of daily living to yield 22%. Using the combined tables, he combined 22% with 1% for surgery at a second level (L4/5) and 3% for radiculopathy, yielding 25% whole person impairment. No error is alleged in respect of this assessment.
At [11], Medical Assessor Anderson gave the following reasons for deducting 4/5ths for a pre-existing injury or condition – emphasis added:
“There has been previous surgery at the L5/S1 articulation. The best estimate of whole person impairment following that procedure comes from Specialist Orthopaedic Surgeon, Dr James Powell in his report of 24/02/14 with 20% WPI. My unaltered’ whole person impairment following this assessment which addresses the situation of Mr Houting’s lower lumbar spine where there has been a fusion from L4, across L5 and inserting at S1 is calculated to be 25%. Therefore, I would suggest that the most logical way of addressing any deduction is for the deduction of the previous figure calculated for the fusion at L5/S1. This is 20%. Therefore, strictly speaking, there should be a deduction of 20/25ths (4/5ths). This therefore reduces the whole person impairment of 25% down to 5% for this most recent event.
I previously made reference to the deduction calculated by Dr Tom Mastroianni of one-fifth and also by Dr Frank Machart of half. With the greatest of respect to both specialists, whilst at face value either deduction does seem reasonable, this would be appropriate if we did not know much about the previous condition at L5/S1. In this situation, however we do know very accurately that this was assessed by Dr James Powell at 20% WPI. I am therefore persuaded that the correct approach is for this to be deducted.”
At [4], he had taken the following history of treatment following a previous injury, under the heading, “Details of any previous or subsequent accidents, injuries or conditions”:
“On 15/08/12, he was unloading a bulldozer from a low loader. Unfortunately he fell off this onto the ground. This resulted in discogenic pathology at the L5/S1 articulation. He came under the care of Specialist Neuro-surgeon, Dr Michael Ow-Yang who carried out a posterior fusion at the L5/S1 articulation on 04/06/13. This gave Mr Houting a very good result. Before the operation, he apparently had radiculopathy down the right leg, although this appears to have been resolved following the surgery. He was able to get back to his full time work as a truck driver, which was the task he was doing when the injury of 07/08/20 occurred.”
Earlier at [4], he had taken the following history of injury on 7 August 2020 and its surgical treatment:
“Mr Houting got out of his tipper truck to move a rock out of the way so that he could unload the gravel from the tipper truck on 07/08/20. As a result of this event, he experienced increasing lower back pain. He ended up under the care of Specialist neuro-surgeon, Dr Michael Ow-Yang. (Dr Ow-Yang had operated on his lower back previously, in June 2013.) On this occasion, Dr Ow-Yang carried out a fusion, which extended from L4 across L5 to S1. This gave Mr Houting significant improvement, although he continued to have radiculopathy features down the left leg. With difficulty, he has been able to return to his previous occupation. …”
Section 323 of the Workplace Injury Management and Workers Compensation Act 1998 (1998 Act) provides for a deduction “for any proportion of the impairment that is due to any previous injury … or that is due to any pre-existing condition or abnormality”.
In determining whether to make a deduction, a Medical Assessor must determine whether there was a pre-existing injury, condition or abnormality and, if so, whether it currently contributes to permanent impairment.
Mr Houting had suffered a previous injury to the disc at L5/S1 on 5 August 2012. To treat the effects of that injury, he came to L5/S1 decompression and fusion surgery on 4 June 2013. That amounts to a pre-existing injury, giving rise to a pre-existing condition at L5/S1, for the purposes of s 323.
The Medical Assessor was required to consider whether the injury at L5/S1, or the condition which resulted from surgery at that level, contributed to current impairment, which he had assessed at 25%. He had assessed a DRE category IV impairment due to lumbar spine surgery, the criteria for which include loss of motion segment integrity: Table 15-3 of AMA5. Though he did not expressly identify the L4/5 motion segment, it is obvious that that was the basis of the assessment, because that was the site of the surgery which followed injury on 7 August 2020.
He did not explain why he considered that the previous injury and fusion surgery at L5/S1 currently contributed to impairment. The fact that Dr Powell assessed 20% whole person impairment following L5/S1 fusion performed on 4 June 2013 does not explain why the condition which resulted from the surgery (or the injury which caused the surgery) now contributes to impairment. The inadequacy of reasons demonstrates error.
To determine whether injury in 2012, or the resulting condition at L5/S1, contributed to current impairment, the Medical Assessor was also required to consider whether, but for the 2012 injury and the resulting fusion at L5/S1, the impairment would not be as great: Ryder v Sundance Bakehouse [2015] NSWSC 526. Medical Assessor Anderson did not address that issue. This also demonstrates error, requiring that the Medical Assessment Certificate be set aside.
Instead, he reasoned that, having regard to the assessment of 20% whole person impairment by Dr Powell on 24 February 2014, it is likely that the worker’s functioning was impaired to that extent when he suffered injury on 7 August 2020, and that the later injury increased the extent of his whole person impairment by a further 5%, from 20% whole person impairment to 25% whole person impairment.
That reasoning, too, was in error, because, even though the Medical Assessor had mentioned earlier at [4] that, “With difficulty, he has been able to return to his previous occupation”, in his reasoning at [11] quoted above, he did not explain how, in those circumstances, whole person impairment as at August 2020 (as distinct from February 2014) could possibly have been as high as 20%.
In effect, he made an assumption that, because whole person impairment was assessed at 20% by Dr Powell as at February 2014, it followed that it remained at that level immediately prior to injury on 7 August 2020. No reasons were given to justify a finding to that effect. This also demonstrates error.
Assessment
The Panel is able to correct these errors without further examination.
As indicated, Medical Assessor Anderson assessed 25% whole person impairment in respect of the lumbar spine, before deduction. No error is alleged in respect of this assessment.
The first question to be addressed is whether the injury in 2012, or the fusion at L5/S1 which resulted from it, now contributes to impairment. That was answered in the affirmative by the Medical Assessor, at least by necessary implication. It is not clear to us that the appellant complains of any error in this regard but, as we are satisfied that there is the necessary contribution for the reasons which follow, nothing turns on it.
Like Dr Mastroianni and Dr Machart, treating surgeon Dr Ow-Yang considered that fusion from L4 to S1 was necessary to treat the effects of injury in 2020, because of the effects of adjacent segment disease. As he put it in his pre-operative report of 11 February 2021:
“Typically, in the setting of adjacent segment disease, extension of the fusion [at L5/S1] is required.”
We agree with the opinion of the treating surgeon. It follows that injury in 2012, which resulted in the fusion at L5/S1, contributed to the need for fusion surgery from L4 to S1.
To determine whether injury in 2012, or the resulting fusion at L5/S1, currently contributes to impairment, we must also be satisfied that, but for injury in 2012 or the L5/S1 fusion, current impairment would be less: Ryder.
In his report of 11 February 2021, Dr Ow-Yang advised against microdiscectomy at L4/L5, because “in the setting of adjacent segment disease, there is a high probability of further structural decompensation and the need for eventual extension of the fusion”. However, it does not follow that, but for the L5/S1 fusion, microdiscectomy would have been likely, or even reasonably available. No such suggestion was made by Dr Ow-Yang.
In our view, a fusion at L4/5 would have been indicated and likely, even without fusion at L5/S1. According to Dr Ow-Yang, the worker had suffered “severe low back pain radiating to the left lateral thigh and lateral calf with numbness in the left foot’ as a result of injury in August 2020. The pain was ‘severe and disabling”. Steroid injections gave no lasting benefit. MRI demonstrated broad-based posterior disc bulge causing severe bilateral lateral recess stenosis and severe bilateral L5 nerve compression.
In those circumstances, it is likely that the disc was degenerate, and in danger of collapse. It was imperative that motion at L4/5 be minimised, in order to prevent such an outcome, and to minimise radicular pain and other symptoms. A microdiscectomy could not achieve this result, because motion would be preserved, causing instability and further deterioration. The only reasonably available option was fusion surgery. In our view, fusion at L4/5 would have been necessary, even if there had been no adjacent fusion at L5/S1.
It follows that, even without the pre-existing fusion at L5/S1 or the injury which caused it, there is no evidence that current impairment would be less. The test in Ryder is not satisfied. No deduction is available for the pre-existing fusion at L5/S1, or the injury which caused the need for it.
However, as noted by Dr Machart, an MRI scan dated 24 August 2020 demonstrated degenerative change prior to injury in 2020. At L4/5, the radiologist noted “mild broad based disc bulge with mild to moderate central disc protrusion resulting in moderate central canal stenosis. Facet joint osteophytes contact but do not compress the exiting L4 nerve roots bilaterally.”
The presence of osteophytes demonstrates that the facet joint degeneration at L4/5 was well advanced, and makes it highly likely that this degeneration existed prior to injury on 7 August 2020. There is no evidence that the disc bulge did so.
As Dr Machart reported on 27 July 2022, the back remained symptomatic prior to injury on 7 August 2020. This is consistent with facet joint degeneration at L4/5, particularly one as advanced as that demonstrated by the MRI of 24 August 2020. We are satisfied that the degenerative facet joints were symptomatic. In those circumstances, fusion surgery at L4/5 would have been necessary to treat the advanced state of facet joint degeneration. In our view, the facet joint degeneration itself also contributed to the need for fusion surgery at that level, and therefore to the assessed impairment.
However, it cannot be said that, but for the facet joint degeneration, current impairment would be less. That is because (as we have found) fusion at L4/5 would have been required in any event as a result of injury on 7 August 2020. The test in Ryder is not satisfied. There is no basis for a deduction.
Conclusion
The Medical Assessment Certificate of Medical Assessor Anderson is revoked and replaced with the attached Medical Assessment Certificate.
PERSONAL INJURY COMMISSION
APPEAL PANEL
MEDICAL ASSESSMENT CERTIFICATE
Injuries received after 1 January 2002
Matter number: | M1-W7575/22 |
| Applicant: | John Houting |
| Respondent: | State of New South Wales (Forestry Corporation of NSW) |
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 Medical Assessor Anderson 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, | 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) |
| Lumbar spine | 07/08/20 | Chap 4 P 24 | P 384 T 15-03 | 25 | 0 | 25 |
| Scarring | 07/08/20 | P 74 T 14.1 | 1 | 0 | 1 | |
| Total % WPI (the Combined Table values of all sub-totals) | 26% | |||||
0
3
0