More than one lesion — the hardest configuration, and a common one

One knee, more than one lesion — sometimes in one compartment, sometimes in both, sometimes facing each other across the joint (“kissing” lesions, where the two damaged surfaces articulate against each other). It is the hardest configuration this operation treats, and the one the cell-therapy techniques are specifically indicated for: unlike a plug of transplanted bone, cultured chondrocytes can be laid into several defects in one operation.

It is also common in exactly the population reading this site. The long patellofemoral series are full of multiple and kissing lesions, and a knee bad enough to reach a two-stage cell operation is rarely a knee with one tidy defect.

In the five-year patellofemoral series the whole cohort stayed well above where it started, but it did not hold flat: mean IKDC ran 46.1 before surgery to 77.1 at two years and back to 70.4 at five. Patients with patellar and multiple lesions were the ones who declined between years two and five — the window after supervised rehabilitation ends.^E48

That decline finding is the single most actionable sentence in the multifocal literature. Years two to five are precisely when supervised rehabilitation has ended and most people stop training — and quadriceps strength is the variable repeatedly associated with long-term outcome. It is the evidence-based argument for treating this as a long-horizon program rather than a discharge-and-forget one.

At 12.6 years — the longest patellofemoral horizon in print — 72% of patients were better or unchanged and 93% said they would have the operation again, with good results preserved even in multiple and kissing lesions, though patients without kissing lesions had the better prognosis.^E49

Read together: multifocal disease does worse than an isolated femoral condyle lesion, carries more reoperations, and still overwhelmingly clears the bar patients actually care about — being glad they did it. Good but lower, not good versus hopeless.

The two locations' rehabilitation programs protect opposite things: the tibiofemoral protocols restrict weight-bearing while allowing motion, and the patellofemoral consensus allows immediate weight in a locked brace while restricting flexion under load.^E5E4

A reader with grafts in both compartments inherits both sets of restrictions at once, and no study says which one governs where they collide. The combined mode exists for exactly this: it shows both programs, marks every point where they disagree, and resolves a disagreement only where this site has written out its reasoning — labelled as the author's inference, never presented as studied.