Table 3.

Tibio-femoral mechanical angle malalignment (cTFmA)

Author	RAQ criteria for radiological bias	Association between malalignment and worse outcome	Sample size	Alignment data	Findings
Parratte et al. (2010)	Low risk	No	398	292 knees classed as mechanically aligned 0° ± 3. 10 knees in the outlier group (beyond 0° ÷ 3°	15.4 % revision rate in the mechanically aligned group. 13 % in the outlier group (p = 0.88). No association between malalignment and revision
Bonner et al. (2011)	Low risk	No	458	372 knees were classified as mechanically aligned (0° ± 3°). 86 knees were within the malaligned group	33 revisions for aseptic loosening. Kaplan–Meier survival analysis showed a weak tendency towards improved survival with restoration of a neutral mechanical axis, but this did not reach statistical significance (p = 0.47)
Magnussen et al. (2011)	Low risk	No	553	181 patients were in varus alignment, 352 were in neutral alignment and 20 were in valgus alignment	No statistically significant difference in revision rates between the three groups (p = 0.15)