The argument on this site claims that the neighbouring joint dominates planning — it does at the hip, the ankle, the thumb and, most dramatically, the elbow. The wrist was named in advance as the test that could break that claim, and it breaks it. No neighbour compensates here. The midcarpal joint does not absorb the radiocarpal disease; in a proximal row carpectomy it is resected. Something else decides this operation.
Read this wrist → What the failed test actually showed →Chapter sixteen of the thesis lists six ways the argument could be wrong. The fourth is: examine joints with obvious neighbours — the elbow, the wrist — and find that the neighbour's behaviour does not dominate planning there. Both were built. The elbow confirmed the pattern more strongly than any joint so far. The wrist does not show it at all.
| Joints with an adjacent segment | The wrist | |
|---|---|---|
| What the neighbour does | Compensates, shares, or refuses to | Nothing. It is resected in the operation |
| Second position | Seated film, Coleman block, pull test | There is none |
| What decides the operation | Whether the neighbour will move | Which articular surfaces are still intact |
| The reference | The neighbour's behaviour | Surviving anatomy |
There are two families, not one. Joints that are mechanically coupled — a chain like spine-pelvis-hip, a chain like ankle-subtalar, a linkage like thumb base to thumb MCP, a ring like elbow-membrane-wrist — have adjacent segments that dominate planning. Joints that fail by surface attrition — the shoulder's glenoid, this carpus — do not. There the reference is built from what survives.
That is a better hypothesis than the one it replaced, and it only became visible because a joint was tested that did not fit. A programme that only built the joints that agreed with it would still be claiming one pattern.
Resect the scaphoid, lunate and triquetrum and the capitate articulates with the lunate facet of the radius. That is the whole mechanism, and it is why the operation has exactly two prerequisites. When the proximal capitate is degenerate the procedure is not harder. It is excluded.
Still a problem about the ligament or the nonunion itself. Salvage is not yet the conversation.
SLAC staging →Exactly and only what proximal row carpectomy requires. Four-corner fusion is also available, and the choice is about what the patient does with the hand rather than what is left of it. Four-corner fusion has shown better grip strength and radial deviation.
Treatment options for stage II →A surface the carpectomy depends on is gone. Four-corner fusion becomes the route because it does not ask the capitate head to become a bearing surface.
Where PRC becomes contraindicated →The radiolunate articulation has gone too. Partial salvage has nothing left to build on, and the conversation is total fusion or arthroplasty.
Capitolunate arthrodesis →Every other instrument on this site computes something — a window width, a correction budget, a residual, a translation. This one does not, because there is nothing here to compute. The inputs are categorical, the gate is binary, and the output is which operations remain available. That is not a shortcoming of the instrument. It is what this joint is like, and it is the evidence for the two-family distinction above.
The findings above are attached. Contact details only.
Telemetry for calibration, not a clinical record. No patient identifiers.