To succeed in a claim for damages for personal injury, and equally in clinical negligence claims, it is necessary for the claimant to prove (on the balance of probabilities):

(i)          that the defendant is in breach of a duty owed to the claimant;

(ii)         that injury, loss or damage has been caused to the claimant (sufficient to form the basis of a claim in law) as a result of the breach of duty; and

(iii)        the nature and extent of the injury, loss or damage sustained.

Under (ii) it is necessary to prove that some (more than minimal) damage has been suffered in order to have a cause of action (a black eye or painful neck or back will be enough).  This is referred to as ‘legal causation’.  Without some (more than minimal) damage there is no claim.

Once it is proved that there has been some damage, it is for the claimant to prove the extent of the damage caused by, or arising from, the breach of duty. This is referred to as ‘factual causation’.

In order to establish that there is some damage and its extent, it is necessary to address what the position would have been ‘but for’ the breach of duty, and to compare this with the position that has occurred and will occur in the future.  Damages will be awarded for this difference – the damage caused by or arising from the breach of duty.

This can frequently be the main battleground between the parties to litigation.  The question therefore is, even if there was a breach of duty – for example negligence – did it make any difference (legal causation), and if so, what difference (factual causation).

There are several ways of expressing the test. Lawyers often refer to causation as the ‘but for’ test:

…”but for”, or “in the absence of”, or “without the act or omission, what was the claimant’s situation likely to have been in any event?”

Then it is necessary to go on to see if the situation as it is now is different, and if so, in what way.  Judges and lawyers alike want to know what injuries, if any, the claimant has actually suffered as a result of the accident. Usually, there is little difficulty in identifying the injury (or injuries) with which the claimant has presented. However, one of the most important purposes of a medical expert report is to distinguish between those injuries, symptoms, effects and consequences that have been caused by the accident (or adverse event) from those that have not. In all injury claims expert medical evidence is crucial in addressing causation.  It may be necessary for a number of experts within different disciplines to address different aspect of the alleged injury.

The crucial point to remember is that a claimant can only recover damages for the consequences arising from the accident and not for anything that would probably have occurred or been suffered in any event. The medical evidence must establish clearly which of the claimant’s complaints and concerns since the accident and which of the concerns in relation to the claimant’s medical health for the future are a consequence of the accident and would not have arisen in the absence of the accident.

A very real difficulty for the medical expert is that in clinical practice the issues of causation and of consequential loss are not generally part of a medical practitioner’s assessment of a patient and are not written about in medical reports to colleagues or in learned articles. For the most part, causation is irrelevant to medical practice. What the patient’s situation would have been if the circumstances were to have been different is of no, or very little, significance.

Having a clear understanding of causation is one of the fundamental components of the medico-legal mind which an expert must develop. So, also, is expressing the opinion on causation in accurate and precise language which the lawyer will immediately understand.

The difficulty in forming opinions on causation is that a claimant may have had some symptoms prior to the accident, on to which the symptoms resulting from the injury have been superimposed. The claimant may have had a pre-existing condition which was likely to have an impact on quality of life in due course in any event.  There may be pre-existing degenerative changes, asymptomatic prior to the accident but contributing to the situation since the accident or which might do so in the future. There may also be some other unrelated disease or condition that will affect the future. All of these issues can make causation a challenging principle to apply.

A further difficulty is that when addressing causation, the medical mind is far more comfortable with giving opinions on the situation as it is now than on giving opinions on what the situation would have been in the absence of (i.e. but for) the accident. The ‘medico-legal mind’ understands that without the second half of the opinion dealing with the ‘but for’ position, the opinion is incomplete and the claim cannot be valued – the medico-legal report is therefore useless!

Learning point:

Every medical expert addressing quantum, and therefore the value of a claim, must have the issues of causation in mind, whether dealing with what may appear to be a simple road traffic claim or a complicated clinical negligence.  Simply taking at face value that the condition of the claimant now is the result of the accident or adverse event concerned is potentially negligent.

Every such medical report must clearly set out the situation as it now is, and will be into the future, and also the situation as it would have been but for the accident or adverse event, and must explain and describe the difference between the two situations.

The topic is dealt with in a great deal more detail in Writing Medico-Legal Reports in Civil Claims – an essential guide (2nd edition 2015), published and sold by Professional Solutions Publishing (www.prosols.co.uk)

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It is interesting to see a case in which the claimant in a clinical negligence claim is faced with a body of practitioners who would have done precisely what the defendant surgeon did, and yet the claimant is still able to establish liability. A recent example is Bradfield-Kay v Cope [2019] EWHC 2881 in which judgment was given on 21^st May 2020.

Bolam[1] says that a surgeon is not guilty of negligence if he has acted in accordance with a practice accepted as proper by a responsible body of surgeons in that field of practice even if there is a body of opinion who would take a contrary view.  Bolitho emphasises that the practice has to be one accepted as proper by a responsible body of medical men, so that the exponents of that practice have to be able to demonstrate that such an opinion has a logical basis.

In Bradfield-Kay v Cope the claimant underwent a left total hip replacement after which he developed serious thigh and groin pain.  Subsequently he required a left hip revision and the revision surgeon recorded ‘The cup was found to be retroverted and the anterium of the cup was prominent and was catching on the anterior structures’.

The claimant’s allegation was that the surgeon had been in breach of duty in permitting the acetabular component of the prosthetic hip to be prominent and in such a position that the iliopsoas tendon caught on it, that is that the cup protruded beyond the acetabular rim.  The judge made the following findings of fact:

(1) The prominence of the acetabular component was more than negligible and it was not within the confines of the ‘native’ acetabulum.

(2) The version of the socket was less than expected, the revision surgeon’s note indicating that it was a significant version. And therefore the cup was not placed at an appropriate degree of anteversion.

(3) The version of the socket was such as to cause the acetabular component to be prominent.

(4) The prominence of the acetabular component was sufficient to cause irritation of the left iliopsoas tendon.

The judge went on to find, on the evidence before him, including the expert evidence, that some surgeons allow the acetabular component to stand prominent from the native bone, and therefore there is a body of surgeons undertaking total hip replacements who do not ensure that the acetabular component is not placed in a position that could interfere with the iliopsoas tendon.  Indeed the defendant surgeon gave evidence that although he had undergone three training sessions on THR, he was not taught to check that the cup did not protrude beyond the acetabular rim.  The claimant’s expert, while critical of this, could not refer to any textbook or handout from any presentation to demonstrate that the practice of checking that the cup was not prominent was accepted throughout the profession as standard either at the time of the operation in 2009 or indeed now.  Further the experts accepted that there were circumstances when it is not possible to ensure that the socket is not prominent, for example because of the anatomy of the patient, although this was not one of them.  The judge found his conclusion supported not only by the evidence of the defendant surgeon but also by the fact that the Defendant’s expert had carried out many revision arthroplasties where it was plain that other surgeons took a view similar to the defendant surgeon.

The judge held that both Bolam and Bolitho required the court to examine the different schools of thought and to ask whether the one relied upon by the defendant could demonstrate that its exponents’ opinion had a logical basis.

He went on to conclude that there was no logical basis for neglecting to ensure that the acetabular component was not placed in a position that could interfere with the iliopsoas tendon, and no good reason had been put forward for not taking this precaution.  The risk of impingement was a well-recognised risk.  Therefore the patient was entitled to expect a competent hip surgeon at the relevant time to ensure that the acetabular component was placed so that it did not interfere with the iliopsoas tendon and the allegations of breach of duty and negligence in relation to the placing of the acetabular cup were made out and liability was established.

The judge’s conclusion was therefore that although there is a body of surgeons undertaking total hip replacements who do not ensure that the acetabular component is not placed in a position that could interfere with the iliopsoas tendon, that body is not a reasonable, or responsible, or responsible, or reasonably competent, body (Bolam) and/or that that body cannot demonstrate that its opinion has a logical basis, for example when weighing the comparative risks and benefits of that practice (Bolitho).

It followed that the defendant surgeon was being held to a standard of which he was unaware at the time of the criticised surgery, but that that standard was one which the patient was entitled to expect from a competent hip surgeon.

Learning point:

This is a useful reminder that simply because a doctor acts in a manner followed by a body of other doctors does not necessarily mean that the doctor has an answer to a claim in negligence.  If the practice of that body of doctors can be shown to be lacking a logical basis then it is not the practice of a body of ‘responsible, reasonable or respectable’ doctors, and will not provide the doctor with a defence.

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[1] Bolam v Friern Hospital Management Committee [1957] 1 WLR 583