When a spinal surgeon’s opinion on fixation adequacy should defer to radiological interpretation

The evidential scope of spinal surgery and radiology

A spinal surgeon’s expert report typically addresses the operative rationale, procedural steps, and whether the choice of fixation fell within a responsible body of professional opinion, as established in Bolam v Friern Hospital Management Committee [1957] and qualified by Bolitho v City and Hackney Health Authority [1998]. While surgeons routinely interpret imaging to inform clinical decisions, their legal evidence is primarily directed at the appropriateness of the surgical intervention and the management of risks.

A consultant radiologist, by contrast, possesses specialised expertise in the systematic review of imaging, including the detection of hardware displacement, pseudarthrosis, or the integrity of the bone-implant interface. Where the dispute in litigation concerns the mechanical adequacy of fixation or radiologically occult findings, the radiologist’s report may provide the most reliable evidential basis. Instructing a surgeon to opine on complex imaging findings outside their formal training may weaken the evidence, particularly under cross-examination.

Evidence requirements for fixation adequacy

To establish a factual position on whether fixation failed or was improperly placed, the evidential base should include:

• Operative notes describing the surgeon’s intra-operative assessment of hardware stability.
• Pre- and post-operative imaging, ideally including both plain radiographs and cross-sectional imaging such as CT or MRI.
• Long-term serial imaging where late-onset hardware failure is alleged.
• The patient’s clinical records, documenting the timing of symptoms relative to the procedure.

Where these documents are incomplete, any expert opinion may be limited. A surgeon may opine on whether the choice of instrumentation was consistent with clinical indications, but they cannot retrospectively certify structural integrity if the imaging is of insufficient quality or if the radiologist’s interpretation remains in dispute. In such cases, the court may direct that a radiologist be instructed to clarify findings or reconcile conflicting interpretations.

Division of opinion between disciplines

The distinction between surgical and radiological evidence is particularly relevant during expert discussions under CPR 35.12. Where a claim alleges that spinal fixation caused neurological injury, the surgeon’s focus is typically on the surgical approach and the documented risks discussed under the Montgomery v Lanarkshire Health Board [2015] framework. The radiologist, however, addresses the objective spatial relationship between hardware and neural structures.

When instructing experts separately, the letter of instruction should clearly define the scope of each expert’s duty. A common pitfall is asking the surgeon to conclude on the cause of a nerve root injury when that determination depends on the radiological interpretation of screw trajectory. The surgeon’s opinion on causation is contingent upon the radiologist’s findings regarding hardware positioning. If the radiologist concludes the hardware is correctly positioned, the surgeon’s assessment of reasonable care may be strengthened, but this does not replace the need for the radiological evidence itself.

Procedural considerations under CPR Part 35

Under CPR Part 35, the court may restrict expert evidence to what is reasonably required to resolve the proceedings. Where a dispute primarily concerns imaging interpretation, the court may question the adequacy of instructing only a surgeon. If radiological evidence is contested, the court may direct a single joint expert under CPR 35.7 or permit two experts in the same discipline where necessary for a just resolution.

Instructing solicitors should note that written questions to an expert under CPR 35.6 must be proportionate to the issues. Where a surgeon’s report lacks a radiological foundation, the opposing party may use this mechanism to probe whether the surgeon’s conclusions rely on their own imaging assessment rather than a radiologist’s findings. This may affect the weight the court assigns to the evidence on breach and causation.

Instructing a radiologist is not merely supplementary; it may be essential to the validity of the surgeon’s opinion. Where imaging reveals objective evidence of hardware failure, the surgeon’s role is to assess whether that failure represents a breach of duty or a known, non-negligent complication. Separating these functions ensures the evidence is technically precise and compliant with the court’s expectations for expert testimony under CPR 35.3.