Harpur v State Rail Authority (NSW) [2000] NSWCC 3; (2000) 19 NSWCCR 256 (24 January 2000)

Last Updated: 30 October 2000

[2000] NSWCC 3; (2000) 19 NSWCCR 256

HARPUR v STATE RAIL AUTHORITY (NSW) & ANOTHER

[2000] NSWCC 3

Compensation Court of New South Wales: Burke J

18 October 1999 (H)

24 January 2000 (J)

Workers compensation - Injury - Relationship to employment - Substantial contributing factor - Concerned with causality not consequence of injury - Requires evaluation of all operative factors in chain of causation - Whether a substantial factor depends on employment's importance relative to other factors - Not a mathematical calculation but a matter of impression - The context is crucial - Workers Compensation Act 1987 (NSW), s 9A

Words and phrases - "substantial contributing factor" - Workers Compensation Act 1987 (NSW), s 9A

J.T. Kearney, for the applicant

G.P. Neilson, for the second respondent

Cur adv vult

1 BURKE J: The applicant, at the outset of the trial, sought relief against both the State Rail Authority (SRA) and the Railway Services Authority (RSA), two discrete claims being heard together by consent. Part way through the applicant's evidence in chief, the first respondent and the applicant agreed upon redemption and commutation of the worker's entitlements. The hearing thereafter proceeded only against the second named respondent. At the conclusion of the evidence and submissions the redemption and commutation in respect of the claim against the first respondent were implemented.

2 The following day I had proposed to give judgment in respect of the claim against the second respondent but overnight became enmeshed in the submissions, somewhat superficial, regarding the application of s 9A. This was a subject which I had always wished to know about but had been too afraid to ask. Come the dawn I thought it time to ask and in lieu of delivering judgment required written submissions by the second respondent and the applicant. These were duly provided.

The claim against the second respondent

3 The applicant seeks an award of weekly payments from 15 April 1998 to date and continuing together with medical expenses of treatment. That entitlement is alleged to arise as the result of injury to his back, neck and right ankle received as the result of the nature, conditions, incidents and obligations of his employment by the second respondent between 1 July 1996 and 27 April 1998 together with a specific incident occurring on 14 April 1998. He makes no claims in respect of losses under s 66.

Background

4 The applicant as a teenager playing football had injured his right ankle. He says it recovered. Symptomatically that could be reasonably correct though it appears in retrospect that there remained pathological consequences. He later served six years in the army and later still was employed by BHP as a trades assistant. He hurt his back in 1974 at BHP, was treated by Dr Plowman, off work six weeks and resumed normal duty.

5 On 23 August 1982 he came into the employ of the SRA as a fettler. There is a deal of walking on uneven surfaces in that occupation, and a deal of physically heavy work, and during the latter part of that employment, the applicant became progressively troubled by right ankle symptoms.

6 On 2 March 1989 he suffered injury to his back and neck, was off work and treated. He resumed work, had a period of a few months driving a mobile crane, which aggravated back and neck pain, and was transferred to the much less arduous position of flagman. He still complains of aggravating back and right ankle pain thereafter. The transfer had economic consequences, mostly decreased overtime, and on 31 August 1995 in Matter No. 30715/94 an award was made in favour of the worker against the SRA for $100 per week pursuant to s 40 as well as lump sums relating to impairment of the back.

7 Then came the event which is the root cause of this litigation and without which there would probably have been no problem. From 1 July 1996 the fettlers, hitherto employed by the SRA, came under the aegis of the RSA. Nothing was changed regarding the work, just the name of the employer. The RSA is a different legal entity and not responsible to the worker for the effects of any injury prior to 1 July 1996. That change is a substantial cause of this litigation-- begging pardon for the anticipatory use of that adjective.

8 The applicant continued to perform restricted work as a flagman for the RSA. It still involved a degree of walking on uneven surfaces, ballast and access tracks though the heavy physical element was largely excluded.

9 On 11 November 1997 Hunt C entered a consent award against the SRA in respect of an agreed 13.5 per cent permanent loss of efficient use of the right leg below the knee. That arose from the right ankle problem. This being some 18 months after commencement with the RSA suggests that it was not then considered that work with the RSA had contributed to the ankle disability.

10 On 14 April 1998 the applicant was walking along ballast carrying some gear when he trod on a rock, fell across the rails and hurt his knee, back and right ankle. The ankle became swollen, he was off work for a couple of weeks, the back recovered from the effects of the fall. He was given work around the office, doing messages and such like until 28 May 1998 when he was stood down for want of suitable work.

11 On 30 June 1998 and 21 October 1998 he underwent surgery to the ankle, the former a failed replacement because the prosthesis became loose, the latter a more successful revision.

12 In general the applicant deposes that his back gradually worsened over the period with the SRA and RSA, similarly his neck. Notwithstanding such, he maintains that but for his right ankle, he could have carried on in the restricted work of flagman at the RSA. The ankle so inhibits him that he regards himself as unemployable. He was formally terminated by the RSA on 30 June 1999, a few weeks short of his 54^th birthday.

The problem

13 Was the work with the RSA a substantial contributing factor to his injury and hence, secondarily, his incapacity? That is the question posed by s 9A introduced into the legislation by the WorkCover Legislation Amendment Act 1996, effective from 12 January 1997. The section was operative during the greater part of the worker's employment by the RSA. All but the first six months. In any event s 16 in a case involving disease fixes a nominal date of injury at the date of incapacity.

14 As far as the ankle is concerned there is one rather obvious fact that, superficially at least, tends to suggest that employment with the RSA was at least a relevant factor to injury. He had the incident involving the ankle of 14 April 1998, was off work briefly as a result, resumed in lighter work than he had ever done before and ceased active work of any kind on 25 August 1998 and a few weeks later still underwent major ankle surgery. The temporal sequence of events suggests a change in the degree of disability and incapacity around this time. However, other than superficially, it does not, of itself, establish the incident as the probable reason for the change other than as a post hoc, propter hoc inference. Less so does this mere change inculpate the general nature of his work.

15 The resolution of the question raises issues of fact and law, so, turning to the facts:

Factual medical background

[At [16] to [37] his Honour considered the medical evidence and concluded:]

Factual conclusions

38 The applicant has suffered fairly long term back and neck problems. There is no acceptable evidence that anything in the employ of the RSA has had other than transient effects upon either condition. The applicant had been on selected duty because of the back problem in particular over the latter period of his employment with the SRA. He continued to perform the same type of work with the RSA up to the incident of 14 April 1998 involving the right ankle. But for the ankle the applicant maintains that he could continue in the selected type of duty that he had been doing. Any change in the applicant's capacity to continue work for the RSA could only arise from the ankle condition.

39 The SRA was clearly of the view that the applicant's employment by it had aggravated the pathological condition of the applicant's ankle. They accepted liability for the surgical interventions of Dr Laird of June and October 1998. As against the RSA that, of itself, is non-probative. It does not preclude a finding that work with the RSA has aggravated the ankle condition and produced the current incapacity.

40 Before the applicant ever came to employment by the RSA he had advanced degenerative changes in the right ankle. The radiology and arthroscopy within the first couple of months of employment with the RSA showed such and no one suggests that the short period prior to those investigations played any discernible part in producing the changes.

41 The question is then whether the general work, involving walking on ballast and uneven surfaces over a period of almost two years leading up to the event of 14 April 1998, as well as the effects of that event itself together caused further injury to the applicant's ankle.

42 Dr Kerridge appears to suggest that such work would certainly tend to exacerbate symptoms. That does little to assist the applicant. If the basic condition is not aggravated he fails. Otherwise it is like having an infected finger wound which is very sensitive so that every time it is bumped or stressed it hurts more. That merely demonstrates that you already have a sore finger and it will react to such insults by increased symptoms not that the bumping is causing further injury.

43 All specialists regard the underlying osteoarthritis as intrinsically progressive. That is with or without further insult. Increased symptoms generally may only indicate that the condition is progressing naturally. It does not need added insult to account for additional symptoms.

44 The bulk, if not all, of medical opinion inculpates the teenage ankle injury as the initiating factor. It is regarded as the event likely to have set in train the osteoarthritic disease process. This notwithstanding an apparent absence of complaint of symptoms for a considerable time thereafter.

45 It is submitted on behalf of the applicant that it is clear that work with the RSA has worsened the condition of the right ankle. He finished work with the SRA on 30 July 1996. On 16 November 1997 Hunt C entered a consent award against the SRA in respect of 13.5 per cent loss of use of the lower right leg. All subsequent assessments suggest the loss is greater. That deterioration occurred in the employ of the RSA. Therefore the work with the RSA caused that deterioration. Everything in that submission is logical until one gets to the "therefore". That the condition of the leg worsened is clear. Why it worsened is far from clear. Certainly that he happened to be working for the RSA does not logically demonstrate that the work with them was the cause of the deterioration. However, it does leave open that it could have been the work with the RSA that played a part in the deterioration.

46 Independently of assessments of loss there is little doubt that the applicant's ankle did deteriorate to a degree over the period during which he happened to be employed by the RSA. It had been deteriorating for some years previously. The applicant and all the medical specialists make that much clear. That was a deterioration of a disease process. If some years of doing the same work for the SRA as he later did for the RSA was regarded as a factor in that deterioration (and that seems fairly clear) then it would seem likely that the same work with the RSA would also be a relevant factor. Add to that the frank incident of 14 April 1998 and that conclusion becomes persuasive.

47 On the totality of the evidence I would believe that one of the factors that lead to the deterioration of the applicant's ankle was the general work and the incident with the RSA. Prior to 12 January 1987 such a finding would conclude this claim. But no longer.

48 Actually that finding may not be all that conclusive. Cluff v Dorahy Bros [1979] 2 NSWLR 435 adds a gloss to "results from" in the Act. "Results from" like "arising out of" raises the issue of causation. The headnote to the report of the decision highlights one aspect of the causation problem:

If a worker receives an injury in the course of his employment with A which renders him vulnerable to increased disability by the effects of further work; and then, in the employment of B, the work brings about those effects, it is open to a tribunal of fact to hold that the ultimate incapacity has resulted from the first injury, in the employment of A; and it is not to the point that, if the worker had, in these circumstances, proceeded against B, he might have obtained from B an award in respect of the whole extent of his existing incapacity.

So, even if Mr Harpur's incapacity was, in part, due to injury with the RSA it could still be, in the particular circumstances, that such incapacity resulted from prior injury with the SRA.

Substantial contributing factor

49 Under the extant legislation it is now necessary that the applicant establish the probability that the work and incident was not merely a factor but a substantial factor in the process of deterioration that constitutes injury. Obviously the evaluation of that question requires some concept of what constitutes such a "substantial contributing factor".

50 What constitutes a "factor" has never been a real problem. A factor is one of the elements that contributes to bringing about any given result. If something doesn't contribute to bringing about the result then it isn't a factor at all. The adjective "contributing" is tautological, otiose, redundant. It adds nothing to the substance of the provision. That is progress. Already two-thirds of the problem is resolved. "Contributing factor" poses no difficulties. We are merely left with the question of the function of the adjective "substantial".

51 A number of the judges of the Court have expressed opinions on that matter. There appears to be two major divergent views illustrated by the decisions of Neilson J in Stewart v NSW Police Service [1998] NSWCC 57; (1998) 17 NSWCCR 202; Maher v Brambles Australia Ltd [1998] NSWCC 54; (1998) 17 NSWCCR 334 and Bishop J in Mercer v ANZ Bank [1998] NSWCC 55; (1998) 17 NSWCCR 264 on the one hand and Walker J in Sip v Denerton Pty Ltd, NSWCC, No. 30704/97, 4 June 1999, unreported, incorporating views previously expressed in Jackson v Work Directions Australia Pty Ltd [1998] NSWCC 45; (1998) 17 NSWCCR 70 and Doyle v Manly Pacific International Hotel [1998] NSWCC 44; (1998) 17 NSWCCR 47, on the other.

52 Like Bishop J, I will eschew detailed analysis of cases elucidating the meaning of "substantial". Both Neilson J and Walker J have traversed the gamut of those matters, mostly considering the same sources to reach different conclusions. Neilson and Bishop JJ thought a substantial factor was one that was weighty or big. Walker J expressly negated that proposition. Rather he appears to maintain the equivalence of the test of causation in compensation and tort. He regards both as posing the question whether the relevant circumstance/s relied upon cause or materially contribute to the particular outcome. That question is affirmatively answered if the relevant circumstance contributed something more than de minimis to that outcome.

53 For my part I am quite happy to accept that the test of causation in tort is equiparated to "arising out of the employment" in compensation: Bushby v Morris [1980] 1 NSWLR 81 at 87 where the Privy Council confirmed the oft affirmed equivalence. My logical difficulty thereafter is the simple words of s 9A(3)(a). If the tests were the same prior to the enactment of s 9A then the introduction of that provision was a pretty nugatory affair if it still be so, particularly since the cited subsection specifically says that "arising out of the employment" does not, per se, equate to a "substantial contributing factor".

54 On 20 March 1997 I presented a paper at the annual conference of this Court canvassing the likely impact of the then newly introduced s 9A. There were three quite background themes, though none is particularly germane to the present matter.

55 1. The class particularly vulnerable to the operation of the provision was the group where "in the course of employment" was the entitling factor (e.g. Kavanagh v Commonwealth [1960] HCA 25; (1960) 103 CLR 547; Weston v Great Boulder Goldmines [1964] HCA 59; (1964) 112 CLR 30; Hatzimanolis v ANI Corporation Ltd [1992] HCA 21; (1992) 173 CLR 473);

 2. the provision heralded a possible revivification of the moribund doctrine of "special exposure" (e.g. Brooker v Thos Borthwick & Sons (A'sia) Ltd [1933] AC 669; Craske v Wigan [1909] 2 KB 635), and

3. it indicated a similar possible re-emergence of the doctrine of "added peril" (e.g. Plumb v Cobden Flour Mills Co Ltd [1914] AC 62).

56 I adhere to those general views and have, as yet, found no particular reason to depart from the more specific conclusions reached in that paper from dictionaries; comparison of cases dealing with factors that are material, significant or substantial; analysis of the specific classes of case likely affected by the provision or consideration of the purpose and intent of the provision. So far I agree with myself.

57 Certainly s 9A requires that the employment be a causal factor in an injury. The area of debate seems to be the degree to which the employment must play a causal role. The doctrine of "special exposure" required that the employment must present a risk to the worker beyond that to which the general population was exposed. The causative element must be an "employment" risk. The doctrine of "added peril" held that the causative employment element must truly be inherent in the employment and not arise from a risk introduced by the worker himself. If the worker introduces an added peril and is injured as a result, it was not an injury relevantly causally linked to the employment as such. Section 9A(2) seemed strongly suggestive of this approach. Either of these factors would appear to reduce the substantiality of the employment factor in the causation of injury.

58 In my view the enactment of s 9A was intended to apply a more stringent test to the nexus between employment and injury. The old authorities on "contributing factor" as it stood prior to the amendment now discussed made it clear that such employment factor needed be of little, if any, greater degree than de minimis: see Chalmers v Bank of New South Wales [1979] 53 WCR (NSW) 188; Treloar v Australian Telecommunications Commission [1990] FCA 511; (1990) 26 FCR 316; Watts Peterson Automotive Pty Ltd v Peterson [1994] NSWCC 30; (1994) 10 NSWCCR 653. It merely needed to be "a" factor, of any degree, in bringing about the ultimate outcome.

59 The addition of the adjective "substantial", must, in my view, signify something more. Dictionary definitions of "substantial" have been canvassed in the decisions of Neilson J, Bishop J and Walker J mentioned earlier (see [51] above). One could add the note from "Fowler's Modern English Usage" 2nd ed, 1965:

substantial is now the word in general use for real, important, sizeable, solid ...

That conforms with the meanings ascribed by the Macquarie Dictionary and the Oxford English Dictionary. The Macquarie Dictionary gives the perhaps ironic example of the use of the adjective: "made a substantial contribution".

60 In ordinary usage it is to my mind clear that "substantial" connotes something of weight, size or importance. We speak of a substantial group of the community favouring something or other or a substantial increase in consumer spending in pre-Christmas trading. We are not speaking of some minimal variation. We are speaking of something really obvious. Were I to say that a substantial number of workers would be adversely affected by the enactment of s 9A, nobody could reasonably think that I was talking about some peripheral impact on a few. I would be speaking of effects on a sizeable group of workers. If someone tells you a friend has been involved in a motor accident and suffered substantial injuries you would not conceive that minor abrasions had been suffered. If your wife inherits a substantial legacy you expect more than peanuts. "Substantial" is a common English word conveying imprecise magnitude but an impression that something is serious, weighty, important, sizeable or large.

61 The question is really how big, how sizeable, how important need a factor be to be said to be substantial. There is much discussion in the decisions of this Court cited above of whether the word "substantial" is used relatively or absolutely, qualitatively or quantitatively. In a particular case, if one is judging whether a particular factor is or isn't substantial, that can only be done in the context of the other operative factors. It is the relativity of the particular factor to other operative factors which determines its importance--or substantiality. As has been indicated in the decisions referred to, and those cited therein, in a particular situation several factors may be of importance. If it be so, they may all be substantial. But it is not necessarily so.

62 I have no lament for the inexactitude of the adjective "substantial". I doubt that Deane J did in Tillmanns Butcheries Pty Ltd v Australasian Meat Industry Employees Union [1979] FCA 84; (1979) 27 ALR 367, he merely observed that it was a relative term and, in context, didn't connote any particular quantification. Nor do I think it a "weasel" word (vide Sip at [128]). The word simply requires a value judgment. Every time the word "reasonable" or its derivatives crop up in a statute the decision maker faces precisely the same type of problem. A value judgment is required. The current manifestation of s 52A in some circumstances disqualifies a worker from payments for partial incapacity if he is unemployed "primarily" because of the state of the labour market. Another word expressing relativity of causes requiring an evaluation of relevant factors and a value judgment as to whether or not the labour market is the primary cause. "Primarily" is probably a more stringent requirement than "substantial".

63 The solution to these problems of comparative causes is not capable of being adumbrated in mathematical terms nor being arrived at by substitution of synonyms for the word "substantial". It is not a matter of calculation but rather of impression. That is not new in the law: cf Mahoney JA in Minchinton v Homfray (1994) 10 NSWCCR 778 at 786E in another context. I am relieved that the legislature did not opt for purported exactitude and specify, for instance, that the relevant employment factor must constitute 20 per cent of the relevant causative factors. That would bring the decision making down to a pretty infernal calculus.

64 Nor do I find the indefinite article in "a substantial contributing factor" either a problem or a solution. It could hardly be otherwise. In a particular situation no individual factor might qualify as "the" substantial contributing factor. If a particular condition results equally from hereditary pre-disposition, acquired infection and the effects of trauma then no individual factor is "the" substantial contributing factor but each could well be, and probably is, "a" substantial contributing factor.

65 The one thing I do regard as evident from the judgment of Deane J in the Tillmanns Butcheries case is that relative to all other factors the relevant employment factor must satisfy the requirement of being regarded as being large, weighty, real or of substance--they were the options that he proposed. Yet that which in one context could satisfy that requirement might not in another.

66 The analysis required by s 9A is as to causality not consequence. In the typical "last straw" case the ultimate event may be relatively minor in the chain of causation but actualise quite severe incipient consequences. The end result of disease processes such as cerebral aneurysm rupture or myocardial infarction will often illustrate this proposition. Often the work factor more determines the time at which the catastrophe occurs rather than whether it would occur at all, the latter often being fairly inevitable. Such matters I would think rather vulnerable to the operation of this provision.

Summary

67 Generally, in regard to s 9A, I believe:

1. The provision is concerned with the causality, not the consequence, of injury. The relevant substantial factor is to be identified in relation to the cause of the injury and not in relation to the incapacity or loss. You cannot look to the severity of the consequence of even an immediate cause as a guide to its substantiality as a cause. In the typical "last straw" case the incident may be seen as having catastrophic consequences, as far as effects are concerned, yet have played a minor part in bringing about the injury as such. The very term "last straw" connotes that very concept--the real causes are the other antecedent straws, this incident was just one straw too many but, nonetheless, but one straw among many.

2. "Substantial" connotes more than de minimis. "Substantial contributing factor" in s 9A cannot be equated to the common law test of causation as perhaps could its predecessor "contributing factor": McCooey v Blackwell [1926] 1 WCR (NSW) 1, where Perdriau J held that the words "to which the employment was a contributing factor" are equivalent to the phrase "arising out of the employment". The addition of the adjective "substantial" requires that the relevant factor be accorded a value in the context of the other operative factors. In that context it must be "of substance" to use a comment of Deane J in the Tillmanns Butcheries case.

3. The evaluation of the substance, weight or importance of the relevant factor in the chain of causality must take account of a similar evaluation of that of the other identified factors. Whether, in this web of causation, the relevant factor is or isn't substantial will depend upon its importance relative to those other factors: Manly Pacific International Hotel Pty Ltd v Doyle (1999) 19 NSWCCR 181.

4. There are no absolutes to guide the decision maker. There is no metaphorical line in the sand beyond which a factor becomes substantial. It is all relativities. Fifty yards is obviously a substantial part of a 100 yard sprint and equally obviously not of a middle distance mile. To lose $1,000 is to most a substantial loss, to many not and to Kerry Packer negligible. The context is critical.

5. Alternative expressions are but guides to the decision maker. In evaluating whether a factor is or isn't substantial, guidance may be had from similar terms such as large, weighty, big, important, sizeable, of substance and so forth, but these alternatives are used secundum subjectam materiam: cf Walters v Stavely Coal & Iron Co (1911) 4 BWCC 303 at 305 per Lord Loreburn LC. The question posed by the statute is whether the factor is substantial. That is the question to be decided: cf Jordan CJ in Watson v CC Engineering Industries Pty Ltd [1946] 20 WCR (NSW) 25 citing Lord Dunedin in Plumb v Cobden Flour Mills Co Ltd [1914] AC 62 at 65. The alternatives are used merely to indicate the line of thought and process of evaluation adopted in deciding whether the relevant factor was or wasn't substantial.

This case and s 9A--broadly speaking

68 So the question posed in the present matter is simply whether the two years of work with the RSA and the incident of 14 April 1998 collectively are a causative factor in the applicant's injury producing the present incapacity of such a degree as to warrant being categorised as substantial.

69 The obvious factors leading to the applicant's markedly arthritic ankle are the initial injury as a teenager in the early 1960s; the stresses to which it has since been subject in the 20 years or so following up to employment by the RSA; those non-employment factors subsequent and the stresses of the latter employment. We know that the ankle was markedly arthritic by the time the applicant came into the employ of the second respondent. We know that such was the degree of arthritis that Dr Laird was of the view that major surgery would virtually be inevitable. In the past the applicant had performed heavy and arduous work with a variety of employers. The heavier the work, the more the stress on the ankle. The work at BHP was sufficiently heavy to result in back injury. It would also be sufficiently strenuous to affect the ankle condition. The same could be said of his early years with the SRA.

70 The radiological changes and those visualised on arthroscopy at the very commencement of the applicant's employment by the second respondent demonstrate that the applicant then had a marked degenerative condition affecting his right ankle. That was a result of events over three decades at least. It was a condition intrinsically progressive and was expected to progress by the treating surgeon. The work being done by the applicant was physically light. It did subject the applicant's ankle to a degree of stress. Light though it be, it did involve walking and a degree of that on uneven or unstable surfaces. He had done precisely the same type of work for the SRA for the last several years of his employment by that entity before commencement with the second respondent.

71 The event of 14 April 1998 is equivocal. His ankle may have given way and been itself the cause of the collapse. The stress of walking on ballast may have caused the ankle to "go over" and so cause the fall. Whatever the mechanism it does not seem to be the fall that caused an ankle problem rather than an ankle problem causing a fall, albeit with the conditions of his employment aiding and abetting any such tendency. It seems more demonstration of an existing problem than cause of anything new. The history given to Dr Laird suggests this tendency had been evident to the applicant for some time and well before commencement of employment with the RSA.

72 The applicant's claim form in respect of injury with the SRA on 20 February 1996 demonstrates the applicant's then view of his ankle problem. He reports walking on ballast and aggravating his right ankle which was the site of "long term injury".

73 The overall impression is that the applicant's right ankle osteoarthritis had been increasingly symptomatic for a number of years. That is compatible with the natural history of an essentially progressive disease. Over those years, at least the last five or six years, he had been on selected type work mainly "flagging". That involved a degree of walking on uneven surfaces. That would be a stress to the markedly degenerate ankle. Certainly it would render the applicant probably more symptomatic than at rest--Dr Kerridge accepts symptomatic if not pathological aggravation by such exertions. The effects on the pathology are much more equivocal. Over the period with the RSA there was probably some progression of the underlying pathology. With a progressive disease that is predictable. There may well have been, and I have found effectively that there was, a degree of progression due to the stresses of walking in the conditions that the applicant did while employed by the RSA. I would feel that was rather a minor element.

74 A similar type of situation presented to Ferrari J in Gunter v Gunter & Namoi Council [1966] 40 WCR (NSW) 21. The applicant suffered a series of shoulder injuries in the employment of his father. The treating surgeon said that surgery was then required to remedy repeated dislocations. The worker thereafter entered the employ of the Council. There he again suffered injuries by way of dislocations. Eventually surgery was performed. The question was which employer was liable. His Honour held that the Council was because the incapacity from the day of surgery resulted from the latest, though minor, injury; it determined that he was incapacitated on that particular day and thereafter rather than at some later or even earlier time, when he would necessarily have been incapacitated as a result of the injury with his father.

75 That was a case where a minor injury determined the time of surgery rather than the need for surgery. Had s 9A then been operative it would seem that the decision would likely have been the reverse. The major factor generating the need for surgery was the initial injuries. The subsequent events seem more revelation than genesis, more showing that surgery was necessary than causing such need though obviously a factor in determining when the surgery was performed.

76 I would believe that a similar analysis applies to Mr Harpur's ankle. It was affected by advanced degenerative osteoarthritis prior to commencement of work with the RSA. It continued to degenerate thereafter. An element of such further degeneration was due to the work and incident with the RSA. That element was rather de minimis in the context of the multiplicity of stresses and events which had combined over a lengthy period to bring the ankle to its ultimate state. It was not a substantial contributing factor.

77 The matter has, thus far, been considered on the basis of the minor degree of contribution by the employment with the present respondent to the overall condition of Mr. Harpur's arthritic ankle. Is that the correct frame of reference?

This case and s 9A--narrowly speaking

78 What was the applicant's "injury"? The employment must be a substantial contributing factor to the injury. Mr. Harpur suffers marked degenerative arthritis of the right ankle and so suffered before he came into the employ of the present respondent. Any injury that he received in the employ of the respondent must necessarily be an aggravation, exacerbation, acceleration or deterioration of that disease.

79 While the oral and written submission of neither party addressed this aspect it would seem that the "injury" received by Mr Harpur was just that, an aggravation, acceleration, exacerbation or deterioration of an existing disease within s 4(b)(ii) of the definition of injury and it is therefore to that element only that the employment must be a substantial contributing factor and not necessarily to the disease as such. In other words it could be only to the quite minor aggravation per se that the worker must establish that the employment has been a substantial contributing factor and not to the overall disease which need be attributable to no employment factor at all.

80 In that frame of reference the contribution of the employment factors necessarily acquire an appearance of more substantial impact (a use of that word which I trust connotes of greater weight and importance). In that context the relevant factors over that couple of years of work for the RSA would appear to be the natural progression of the disease itself; the impact of day-to-day "domestic" wear and tear and the impact of the effects of employment. While not easy to distinguish the relative contributions of each factor, the natural progression would appear the more substantial though it would appear that the others were, at least, a contributing factor to the aggravation of the osteoarthritis of the right ankle, as distinct from of the osteoarthritis itself.

81 Neilson J faced a similar conundrum in Maher v Brambles Australia Ltd [1998] NSWCC 54; (1998) 17 NSWCCR 334. Mr. Maher was in his mid-50s and had done laborious work as a motor mechanic for the respondent for something of the order of 12 years. He had a markedly degenerate back. He also suffered from long-term diabetes and polyarthralgia. The evidence was that the latter conditions were largely the cause of the degenerate back. His Honour accepted that the work had exacerbated the condition. The question became whether the work for the respondent was a substantial contributing factor. Whether that was considered in the context of contributing to the overall disease itself or merely to the aggravation is unclear but it was seemingly the former.

82 However, his Honour did advert to some of the paragraphs of s 9A(2), specifically par (d) and par (e), in evaluating the impact of the work. The subsection would be relevant to a similar evaluation in Mr Harpur's case.

83 With regard to s 9A(2)(b) the nature of the work was basically light. It did involve walking. Ambulation is a routine and ubiquitous human operation. That was at times on uneven surfaces. The evidence is blandly indefinite as to the precise degree to which such was involved. There was clearly walking to and from the work site, apparently more than once a day. But there is no indication that the applicant was constantly walking, day in, day out, on uneven surfaces. It was an aspect of his work day.

84 With regard to s 9A(2)(c), the duration of that employment of two years was not particularly long, particularly in the context of a condition that had evolved over 30 years or so.

85 With regard to s 9A(2)(d), the incident of 14 April 1998 could equally have occurred anywhere, working or otherwise--the applicant gave the history of twisting his ankle about weekly to Dr Kerridge.

86 With regard to s 9A(2)(e), the applicant's ankle was in a fairly parlous condition by the time he came into the employment of the present respondent.

87 Taking such considerations into account it appears to me that, while certainly a factor in the aggravation of the disease, the work and incident were not collectively a substantial contributing factor to such aggravation. For the purposes of this matter, the antecedent condition of the ankle could be viewed as if it were an idiopathic problem.

88 Even if, contrary to that view, it was a substantial factor, the question would remain whether the incapacity resulted from the relevant injury as distinct from the underlying disease. Only a small proportion of the itself minor aggravation occurring during the employment with the second respondent was contributed by the effects of "injury". In the overall scheme of things that degree of aggravation was but a straw in the wind. The incapacity and need for the subsequent surgery probably resulted from the prior work with the SRA.

Conclusions

89 I am therefore of the view that the applicant's work with the second respondent, its nature, conditions, incidents and obligations, combined with the event of 14 April 1998 was not a substantial contributing factor to the applicant's injury arising out of his employment with the respondent. Nor, were it relevant, did the ensuing incapacity during the period claimed result from such injury. Section 9A therefore mandates that no compensation is payable.

90 I make an award in favour of the second respondent, Railway Services Authority.

Orders accordingly

Solicitors for the applicant: MRM Solicitors

Solicitors for the second respondent: Leigh Virtue & Associates