Is cementing technique the cause of early aseptic loosening of the tibial component in total knee arthroplasty? A report of 22 failed tibial components

Despite excellent results of bicondylar knee resurfacing when both the tibial and femoral components are cemented, loosening of the cemented tibial component (surface cementing) occurs in approximately 10% of the implants within a 4-year interval after the procedure. Based on our own experience, we want to report of early failed tibial components in 22 patients after a mean follow up of 51 months. This raised the question of whether the cementing technique was implicated in the loosening. All patients were evaluated for radiolucency and osteolytic lesions at the bonecement interfaces by radiographic assessment according to Rossi et al. (a.p. view and lateral view divided into two zones). A malalignment of the components, especially an increased tibiofemoral angle was not evident. The mean radiographic cement penetration in anterior-posterior view was 1.2 mm (SD 0.8) in zone 1 and 1.6 mm (SD 0.9) in zone 2. The mean radiographic cement penetration in lateral view was 1.1 mm (SD 0.4) in zone 1 and 1.3 mm (SD 0.3) in zone 2. In all cases a revision procedure was done. An infection as cause for loosening was excluded using a standardized procedure. A solid bone stock, sufficient PMMA penetration into the spongy bone promotes high initial stability and is essential for solid long term fixation of tibial components if surface only cementing technique is applied. In patients who show poor quality of the periimplant bone such as osteoporosis or osteonecrosis the authors recommend to cement both, stem and underlying surface of tibial components in primary total knee arthroplasty.