The femoral component alignment resulting from spacer block technique is not worse than after intramedullary guided technique in medial unicompartimental knee arthroplasty
- 161 Downloads
Although the spacer block technique has been recommended for the implantation of unicompartmental knee arthroplasty (UKA), there is still a lack of data concerning the resulting component positioning.
This retrospective study included 193 consecutive patients who had undergone medial UKA using the spacer technique. On the basis of the postoperative long standing radiographs, the coronal component alignment was determined in relation to the mechanical axes and the sagittal component alignment in relation to the anatomical axes of the tibia and femur. The coronal alignment of the femoral component was determined through post hoc 3D planning with the CAD data projected onto the radiograph.
The angle of the tibial component was on the average 2.3° ± 2.8° in varus, the femoral component on the average 2.6° ± 3.7° in varus. Only 4 implants (2%) were outside an assumed tolerance range of 10° varus–10° valgus. A tilting from the femoral to the tibial component of more than 10° was observed in 8 cases (4%). A valgus positioning of the tibial component was followed by a valgus alignment of the femoral component (R = − 0.194, p = 0.007). An increased posterior slope of the tibial component led to an extended positioning of the femoral component (R = − 0.230, p = 0.001).
The spacer block technique produces results comparable to the intramedullary guided technique. However, the precision is low and outlier frequent. Due to the possibility of transferring a tibial malalignment to a femoral malalignment, even greater attention should be paid to the precision of tibial resection.
KeywordsUnicompartmental knee arthroplasty Alignment Spacer technique Femoral component
- 3.Kleeblad LJ, van der List JP, Zuiderbaan HA, Pearle AD (2017) Larger range of motion and increased return to activity, but higher revision rates following unicompartmental versus total knee arthroplasty in patients under 65: a systematic review. Knee Surg Sports Traumatol Arthrosc. https://doi.org/10.1007/s00167-017-4817-y PubMedCrossRefGoogle Scholar
- 15.Ham ten AM, Heesterbeek PJC, van der Schaaf DB et al (2013) Flexion and extension laxity after medial, mobile-bearing unicompartmental knee arthroplasty: a comparison between a spacer- and a tension-guided technique. Knee Surg Sports Traumatol Arthrosc 21:2447–2452. https://doi.org/10.1007/s00167-012-2021-7 CrossRefGoogle Scholar
- 20.Tu Y, Xue H, Ma T et al (2017) Superior femoral component alignment can be achieved with Oxford microplasty instrumentation after minimally invasive unicompartmental knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 25:729–735. https://doi.org/10.1007/s00167-016-4173-3 CrossRefPubMedGoogle Scholar
- 22.Zhang Z, Zhu W, Zhu L, Du Y (2016) Superior alignment but no difference in clinical outcome after minimally invasive computer-assisted unicompartmental knee arthroplasty (MICA-UKA). Knee Surg Sports Traumatol Arthrosc 24:3419–3424. https://doi.org/10.1007/s00167-014-3456-9 CrossRefPubMedGoogle Scholar
- 24.van der List JP, Chawla H, Joskowicz L, Pearle AD (2016) Current state of computer navigation and robotics in unicompartmental and total knee arthroplasty: a systematic review with meta-analysis. Knee Surg Sports Traumatol Arthrosc 24:3482–3495. https://doi.org/10.1007/s00167-016-4305-9 CrossRefPubMedGoogle Scholar
- 29.Argenson J-NA, Parratte S (2006) The unicompartmental knee: design and technical considerations in minimizing wear. Clin Orthop Relat Res 452:137–142. https://doi.org/10.1097/01.blo.0000229358.19867.60 CrossRefPubMedGoogle Scholar