Influence of component alignment on outcome for unicompartmental knee replacement

Twice cutting method reduces tibial cutting error in unicompartmental knee arthroplasty

“…The first is that we evaluated only a small number of patients, and the second was that we did not evaluate the relationship between the amount of cutting error and the postoperative outcome. Regarding a component alignment of the tibia using the Oxford UKA, five degrees valgus to five degrees varus and seven degrees posterior tilt to five degrees anterior tilt from the tibial axis have been recommended [18,19]. Therefore, there may be little influence of the horizontal cutting error on the outcome, but the total amount of error in setting the guide, horizontal cutting, keel cutting and implantation error will be large enough to have a possibility of influencing on the outcome.…”

The radiological assessment of total and unicompartmental knee replacements

“…31 In contrast to TKR, mobile-bearing UKRs can have a wide acceptable range of alignment of ±10° varus/valgus and flexion/extension for the femoral component and ±5° varus/valgus and superior/inferior tilt for the tibial component. 32 This forgiveness does not extend to fixed-bearing UKRs, where excessive tibial slope angles outside the range of 8° to 10°l ead to a poor outcome. 32 It is important to stress that component malpositioning should not be considered the same as overall limb malalignment, where overcorrection of the preoperative deformity is associated with a risk of accelerated degenerative changes in the opposite compartment and severe undercorrection is associated with increased wear in the tibial component and recurrence of deformity.…”

“…32 This forgiveness does not extend to fixed-bearing UKRs, where excessive tibial slope angles outside the range of 8° to 10°l ead to a poor outcome. 32 It is important to stress that component malpositioning should not be considered the same as overall limb malalignment, where overcorrection of the preoperative deformity is associated with a risk of accelerated degenerative changes in the opposite compartment and severe undercorrection is associated with increased wear in the tibial component and recurrence of deformity. 33 Varus/valgus alignment for the femoral and the tibial components is measured on the AP radiograph in relation to the anatomical axis of the tibia.…”

CORR Insights®: The Oxford Unicompartmental Knee Fails at a High Rate in a High-volume Knee Practice

“…Immediate postoperative alignment is an objective way to observe how closely some operative criteria were met. Despite recent deemphasis of this principle [5,13], it appears that limb alignment and implant position play an important role in unicompartmental knee replacement survival.…”