Retrospective cohort of 421 posterior cruciate condylar TKAs followed up to 13 years. Examines whether postoperative anatomic alignment — varus (≤4° valgus), normal (5–8° valgus), or valgus (>9° valgus) — predicts implant survival requiring revision. A separate series of 442 revision TKAs provides an independent corroborating dataset.
Going into this paper, there was genuine debate about which direction to err when alignment is imperfect. Townley argued the mechanical axis should fall medial to the knee center; Insall argued lateral (valgus side). This paper settled it with survival data.
When your postop film shows ≤4° anatomic valgus, that knee is already at significantly higher revision risk. A modest overshoot into valgus is not just acceptable — it is preferable to any degree of varus.
In practice, target 5–8° anatomic valgus (neutral mechanical axis). If alignment drifts slightly past 9°, the data show this is well tolerated. If it drifts into varus, revision risk rises sharply. The number worth memorizing: 56% of all revision TKAs come back in varus. This is why modern TKA philosophy treats varus as the alignment error you simply cannot accept.
Retrospective cohort of 421 posterior cruciate condylar TKAs followed up to 13 years. Examines whether postoperative anatomic alignment — varus (≤4° valgus), normal (5–8° valgus), or valgus (>9° valgus) — predicts implant survival requiring revision. A separate series of 442 revision TKAs provides an independent corroborating dataset.
Going into this paper, there was genuine debate about which direction to err when alignment is imperfect. Townley argued the mechanical axis should fall medial to the knee center; Insall argued lateral (valgus side). This paper settled it with survival data.
When your postop film shows ≤4° anatomic valgus, that knee is already at significantly higher revision risk. A modest overshoot into valgus is not just acceptable — it is preferable to any degree of varus.
In practice, target 5–8° anatomic valgus (neutral mechanical axis). If alignment drifts slightly past 9°, the data show this is well tolerated. If it drifts into varus, revision risk rises sharply. The number worth memorizing: 56% of all revision TKAs come back in varus. This is why modern TKA philosophy treats varus as the alignment error you simply cannot accept.