Evaluating Pre-existing Conditions in Orthopaedic Breach Claims

The Clinical-Legal Interface of Causation

In clinical negligence litigation, the assessment of causation frequently hinges upon distinguishing between the index event of an alleged breach and the influence of a patient’s pre-existing orthopaedic condition. Establishing causation often necessitates a detailed review of orthopaedic clinical outcomes, particularly where the patient presents with multi-level degenerative disease or historical injury. Under the traditional but-for test, the expert must determine whether, on the balance of probabilities, the harm would have been avoided absent the alleged breach. However, in complex scenarios, the existence of a pre-existing condition—such as established osteoarthritis or chronic spinal stenosis—can complicate this assessment.

When a claimant alleges that a surgical delay or an operative error exacerbated their symptoms, the expert must account for the natural history of the pre-existing pathology. If the clinical deterioration was inevitable regardless of the breach, the scope of the defendant’s liability under Khan v Meadows [2021] UKSC 21 becomes the primary focus for counsel. The expert’s role is to delineate the injury attributable to the breach from the expected trajectory of the claimant’s underlying health.

Applying the Eggshell Skull Principle

The principle in Smith v Leech Brain & Co [1962] defines the defendant’s liability for a claimant who suffers greater injury than a ‘normal’ individual due to a pre-existing condition. In orthopaedic practice, this commonly arises in cases where pre-existing anatomical variations, such as cervical canal narrowing, may influence the risk profile during procedures. Expert reports should address: Expert Search’s guidance on orthopaedic surgery examines the same instruction questions in more depth.

• Harm resulting from the alleged clinical failure (e.g., intraoperative nerve injury).
• Harm that reflects the natural progression of a previously asymptomatic or symptomatic condition.
• The extent to which the pre-existing condition influenced the initial clinical risk profile and the patient’s baseline vulnerability.

Expert Evidence and CPR Part 35

Orthopaedic cases often involve comorbidities that require a broader clinical view, such as diabetes affecting wound healing or vascular factors impacting recovery. Where cases involve complex interactions between orthopaedic trauma and secondary sequelae, the value of coordinated reporting becomes apparent.

Under CPR Part 35.12, the court may direct experts to discuss their opinions to reach a joint statement, identifying areas of agreement and disagreement. This process assists the court by clarifying the medical issues. Conversely, where a single joint expert is appointed under the court’s power in CPR 35.7, they are instructed pursuant to CPR 35.8. A single joint expert does not engage in a joint statement process with a second expert, as their role is to act as the sole source of expert evidence on a particular issue.

Practical Considerations for Solicitors

When preparing instructions, it is important to provide the expert with comprehensive documentation, including primary imaging, contemporaneous clinical notes, and pre-event medical records. Consider the following when managing the evidence:

• Defining the Scope: Instructions should clearly define the ‘but-for’ state. If the patient had symptomatic osteoarthritis prior to the alleged breach, the expert may be asked to quantify the difference between the patient’s actual and counterfactual functional status.
• Subspecialty Alignment: Select an expert whose subspecialty matches the anatomy and procedure in question. A generalist opinion may occasionally lack the specificity required for complex spinal revision or micro-vascular orthopaedic trauma.
• Early Screening: Consider a merits report to determine whether causation apportionment is likely to be a primary area of contention, or whether the case may hinge on the initial consent process under Montgomery.
• CPR Part 35 Compliance: An expert’s duty to the court, as set out in CPR 35.3, overrides any duty to the instructing party. Ensure that questions are directed toward the medical facts and the clinical reasoning underlying their opinion.

The strength of the evidence in litigation rests on the precision with which the expert applies their clinical knowledge to the facts. By engaging relevant subspecialist consultants, legal teams can ensure that the nuances of a claimant’s orthopaedic profile are appropriately weighted against the evidence of breach, providing the court with a robust clinical narrative.