Lesson 11 — Surgeons do not mix vendors

Over 90% of procedures use implants from a single vendor — that’s the surgical workflow, not a procurement choice

Cross-reference implant events to procedures and a striking pattern appears: more than 90% of multi-implant procedures use implants from a single vendor. When a hip replacement uses three implant components, all three are from the same manufacturer. When a spinal fusion uses screws, rods, and cages, all three come from the same system.

Cross-vendor mixing within a procedure is rare — and the rare cases are usually data-entry artefacts, not real mixing.

Why surgeons single-vendor a procedure

Three operational facts that together explain the pattern:

• Compatibility chains. Implant systems are designed as integrated kits. A hip stem from vendor A has a specific taper geometry; the prosthetic head that mates with it must come from vendor A or a vendor with explicit compatibility certification. Mixing producers a fit-and-finish risk surgeons categorically avoid.
• Instrument trays. Each vendor’s implant system comes with its own trays of instruments — broaches, sizers, impactors, trial implants. Using a vendor A implant requires vendor A’s tray to be sterilised and present. Mid-procedure switching is logistically impossible.
• Surgeon preference. Surgeons train on specific systems. A hip arthroplasty surgeon who uses vendor A’s system for ten years uses it for the next ten years. The choice is sticky for surgical-competence reasons.

The result: a procedure-level implant set is mono-vendor, and the cases of cross-vendor mixing are almost always artefacts.

What the artefacts actually are

Three patterns account for nearly all observed cross-vendor mixing:

1. Supplier-name spelling drift (Lesson 04). The same vendor’s name entered two different ways across the same procedure’s implant rows appears as cross-vendor.
2. Multi-stage procedures recorded as one case. A revision surgery that uses the original implant system plus a new vendor’s hardware looks cross-vendor on the case level — and may genuinely be cross-vendor, but for a clinically valid reason.
3. Free-text vendor entry errors. A nurse documenting implants for a long case may transpose names or copy from the wrong row in the OR documentation.

The genuine cross-vendor cases — where a surgeon deliberately mixed vendors — exist but are rare. The Wisdom is the prior; deviations from it deserve investigation, not celebration.

What changed in the analysis

The signal signal_active_single_source reads cleaner once the procedure-level pattern is the prior:

1. Cross-vendor cases in a single procedure are flagged for review rather than treated as procurement diversity.
2. The thesis interpretation gained an “expected mono-vendor” filter. When a thesis asks about supplier concentration across the hospital, it asks the catalogue-level question. When it asks within a procedure, it acknowledges the mono-vendor prior.
3. Spelling-drift cleanup runs before cross-vendor analysis. A “diverse” procedure that turns out to be one vendor in three spellings is just spelling drift surfacing through the wrong signal.

What stays interesting

• A genuine cross-vendor procedure (verified, not artefact) is almost always a revision case — replacing failed components from an original surgery with a current vendor’s system. Worth surfacing on its own terms, not as a procurement signal.
• A surgeon who reliably cross-vendors is a real outlier — possibly indicating training, possibly indicating preference shift, possibly indicating procurement pressure. Rare and worth understanding.

Why this is in a Lessons journal

Because the single-vendor-per-procedure pattern is a workflow fact that operates above the data. The data shows what it shows; the workflow explains why. Without the workflow, an analyst looking at procedure-level implant data could spend a year trying to surface the cross-vendor signal that doesn’t really exist. With the workflow named, the analyst can focus on the genuine exceptions — which are rare, which are interesting, and which are clinically meaningful.

Sources

• Wisdom: smebit_single_supplier_per_procedure.yaml
• Provider: a hospital OR director with orthopedic surgery oversight
• Anchor signal: signal_active_single_source
• Date Wisdom captured: 2026-05-08