[Comparison of medium-term clinical and radiological outcome between cemented and cementless medial unicompartmental knee arthroplasty]

Cementation of tibial implants in total knee arthroplasty is the gold standard considering the high loosening rates of cementless implants. In contrast, only sparse data exist regarding unicondylar arthroplasty due to its lesser use. In this study, we compare cemented with cementless unicondylar knee arthroplasty and aim to define both clinical and radiological differences in treatment outcome.

In a retrospective study, 106 patients who had undergone a medial unicondylar replacement were examined after a mean postoperative period of 8 years. Of these, 42 patients (median age 81 +/- 7 years) had received a cemented and 64 (median age 73 +/- 7 years) a cementless knee arthroplasty by the same surgeon while 7 patients were deceased or could not be reached. Well-established clinical (VAS, HSS, KSS, UCLA, WOMAC) and quality of life (SF-36) scores were used to evaluate treatment outcome. X-rays were performed to evaluate periprosthetic loosening zones, according to Ewald's criteria.

The cementless patient group presented significantly better clinical scores (HSS, KSS, UCLA, WOMAC), except in the visual analogue scale (VAS) for pain assessment. The quality of life was significantly better in the cementless group except in the subgroups for physical function, vitality and social role, in that it resembles the normal population. Moreover, radiographic analysis using antero-posterior X-rays revealed significantly more and larger periprosthetic loosening areas in tibial zone 2 in the cementless group.

The inferior clinical results characterising the cemented group could be attributed to the higher mean age. Regarding the radiological loosening zones, we did not detect any differences in the techniques of fixation, although physical activity and accordingly mechanical stresses were higher in the cementless group.