Zonal fixation, which divides the distal femur and proximal tibia into epiphyseal, metaphyseal and diaphyseal zones, is widely used to plan revision knee arthroplasty. A Bone & Joint Journal annotation by revision specialists proposes extending this by dividing the femoral diaphysis itself into three zones: distal diaphysis, isthmus and proximal diaphysis.
The rationale is that in multiply revised knees and distal femoral replacements, the diaphysis may be the only bone left for fixation, and its regions differ in shape and quality. A shared classification would allow surgeons to plan stem length and fixation more precisely and to report outcomes in a comparable way.
This is a proposal, not an outcome study. Whether stem fixation in a particular zone improves survivorship has not yet been tested.
For surgeons doing complex revisions, the framework is a useful planning and reporting language, worth adopting in templating and operation notes.
- When templating a complex revision or distal femoral replacement, record which diaphyseal zone the stem will engage.
- Note isthmus position and canal shape on long-leg radiographs before surgery.
- Use consistent zone terms in operation notes so outcomes can be compared later.
- Treat this as a planning language; survivorship benefits are not yet shown.
Why it matters
As revisions accumulate, diaphyseal fixation is often the last option, and a common language is the first step to learning what works.
Don't overread it
This is an expert classification proposal with no outcome data yet.
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