What an orthopaedic surgeon’s report must show to support an opinion on acceleration of osteoarthritis under CPR Part 35 written questions

The necessity of pre-injury baseline evidence

In personal injury and clinical negligence litigation in England and Wales, an orthopaedic surgeon may be asked to opine whether a traumatic injury accelerated pre-existing osteoarthritis. The defensibility of this opinion under CPR Part 35.6 written questions depends on the explicit linkage between objective clinical data and the timing of symptom onset.

An opinion on acceleration relies on demonstrating the radiological state of the joint before the index incident. Where pre-injury imaging is absent, the expert should account for degenerative changes identified in post-injury scans. The report should state whether these changes are consistent with age-related degeneration, systemic conditions, or a traumatic aetiology. If the expert concludes that the condition became symptomatic earlier than it would have but for the index event, the report must specify the diagnostic criteria and radiological evidence supporting this inference.

Speculative statements about the likely progression of asymptomatic degeneration may be vulnerable to challenge under CPR Part 35.6, as they often lack a firm evidential anchor in the patient’s longitudinal medical records. The expert should transparently address any gaps in the records and explain how these influence the certainty of the opinion.

Distinguishing exacerbation from acceleration

A key point of contention is the distinction between temporary exacerbation of a pre-existing condition and its permanent acceleration. An exacerbation refers to a transient increase in symptoms that resolves to the pre-injury baseline, whereas acceleration implies an advancement in the underlying pathology resulting in a permanent reduction in functional capacity.

The orthopaedic surgeon’s report should clearly identify which phenomenon is being asserted. If acceleration is claimed, the reasoning must be supported by comparing the symptomatic trajectory reported by the claimant with the documented history of the joint in general practitioner or hospital records. Where clinical records are silent regarding pre-injury joint pain, the report should explain whether this absence is consistent with an asymptomatic state or reflects common documentation gaps in patients with underlying degenerative change.

Causation analysis in orthopaedic reports

Under the law of England and Wales, causation requires an analysis of whether the injury made a material contribution to the current state of the joint. The expert should address the ‘but-for’ test: would the claimant be suffering from the current symptoms and functional limitations if the index incident had not occurred?

If the expert cannot exclude the possibility that the osteoarthritis would have developed to the same stage independently of the index injury, the opinion should acknowledge this uncertainty. The report should avoid binary conclusions where the clinical evidence supports a multifactorial aetiology. Where other factors, such as occupational history or genetic predisposition, are relevant, the orthopaedic surgeon should clarify the weight given to these factors relative to the index injury.

Scope of orthopaedic evidence and discipline handover

Orthopaedic evidence is limited to the mechanical and biological state of joint structures. Issues such as the psychological impact of pain, long-term employment capacity, or care needs often fall outside the orthopaedic surgeon’s primary remit. A report that strays into these areas risks exceeding the expert’s boundary of expertise.

Where pain persistence is the primary concern but clinical imaging demonstrates successful structural repair, the orthopaedic surgeon may need to liaise with a pain management consultant or psychiatrist. The court may require distinct reports from different disciplines to address the multifaceted nature of the claim. Under CPR Part 35.12, experts may be directed to discuss their opinions and, where possible, produce a joint statement. However, this process is not automatic and depends on the issues in dispute and the court’s direction.

• The orthopaedic surgeon’s report should focus on the anatomical and pathological findings.
• Where psychological or functional impacts are relevant, the expert should clarify the need for input from other disciplines.
• Instructions to the expert should reflect the scope of the disagreement, as defined by the instructing party or the court.

Challenging expert opinion under CPR Part 35

CPR Part 35.6 allows written questions to be put to an expert for clarification. These questions must be proportionate and aimed at elucidating the report rather than challenging the expert’s fundamental clinical judgement. An expert instructed as a single joint expert under CPR Part 35.7 has an overriding duty to the court under CPR Part 35.3 to provide a neutral and impartial opinion.

The report should anticipate potential areas of challenge by documenting the limitations of the available records, such as missing physiotherapy notes or historical imaging, and explaining how these gaps influence the expert’s certainty. An opinion expressed with transparent limitations is typically more defensible than one that asserts a high degree of confidence despite a fragmented evidential base.

The value of an orthopaedic report in quantifying a claim depends on the expert’s ability to map anatomical findings onto the functional prognosis. Where the evidence cannot distinguish between natural progression and traumatic acceleration, the report should state this limitation clearly. This transparency assists the court in determining liability and quantum by defining the boundaries of what is medically certain versus what remains speculative.