Table 4.
Studies investigating association between coronal malalignment and revision rates
| Author | RAQ criteria for radiological bias | Association between malalignment and worse outcome | Sample size | Alignment data | Findings |
|---|---|---|---|---|---|
| Tibial angle malalignment (cTA) | |||||
| Berend et al. (2004) | High risk | Yes | 3152 | 376 knees had >3° varus alignment | 21 revisions due to medial bone collapse all in relative varus. Tibial component with >3° varus had increased risk of failure p < 0.0001 |
| Fang et al. (2009) | High risk | Yes | 6277 | Individual tibial alignment figures not stated | 2.8 times increased risk of failure by medial tibial collapse p = 0.04 |
| Ritter et al. (2011) | High risk | Yes (non significant) | 6079 | 81.9 % knees defined as neutral. Neutral defined as ≥90° | 3.2 % failure rate p = 0.492 |
| Kim et al. (2014) | Low risk | Yes | 3048 | 2168 knees neutrally aligned (90°), 880 varus (<90°) | Varus knees associated with higher revision rate p < 0.0001 No revisions in the neutral group. 30 in the varus group. |
| Magnussen et al. (2011) | Low risk | No | 553 | 35 knees in varus514 knees neutralFour knees in valgus alignment | All revisions occurred in neutral aligned group |
| Femoral angle malalignment (cFa) | |||||
| Ritter et al. (2011) | High risk | Yes | 6079 | Neutral defined as any angle ≥8 valgus. 91.6 % neutral | 7.8 % failure rate associated with valgus malalignment p = 0.0082 |
| Kim et al. (2014) | Low risk | Yes | 3048 | 2858 knees alignment was 2.0–8.0° valgus (neutrally aligned group), in 160 knees the alignment was <2.0° valgus (varus aligned group), and in 58 knees the alignment was >8.0° valgus (valgus aligned group) | 30 revisions overall. 5 % revision rate in varus group (p = 0.001) and 1.7 % revision rate in valgus group (p = 0.1005) |
| Magnussen et al. (2011) | Low risk | No | 553 | 24 knees in varus513 knees neutral16 knees in valgus alignment | All revisions occurred in neutral aligned group |
| Tibio-femoral anatomical angle malalignment (cTFaA) | |||||
| Berend et al. (2004) | High risk | Yes | 3152 | cTFaA—Mean 3.6° valgus for entire cohort. Mean 1.4° valgus for failure group | Varus tibial component alignment >3° (Hazard Ratio 17.2, p < 0.0001) associated with tibial implant failureOverall varus limb alignment associated with failure |
| Fang et al. (2009) | High risk | Yes | 6277 | Mean postoperative cTFaA was 4.8° (± 2.5) valgus. 69 % were in normal alignment (within 1SD of mean) | The revision rate for the neutral alignment group was significantly lower at 0.5 % (21/4029), compared to 1.8 % (18/1222) for the varus group (p = 0.0017) and 1.5 % (12/819) for the valgus group (p = 0.0028) |
| Ritter et al. (2011) | High risk | Yes | 6079 | Neutral defined as 2.5–7.471 % neutral | 8.7 % failure rate when tibial component <90° and femoral component ≥8° valgus p < 0.0001 |
| Kim et al. (2014) | Low risk | Yes | 3048 | 1928 neutrally aligned (3–7.5° valgus), 664 varus aligned (<3° valgus) and 456 valgus aligned (>7.5°) | 30 revisions overall. 2.3 % revision rate in varus group (p = 0.005) and 0.9 % revision rate in valgus group (p = 0.91) |
| Morgan et al. (2008) | Low risk | No | 197 | 73 neutral (4–9° valgus)58 valgus (>9°)66 varus (<4.9°) | Six revisions overall. No significant difference between groups (p = 0.78) |