Medialised Dome and Anatomic Onlay Patella Designs in the Modern Posterior Stabilised Rotating Platform Total Knee Arthroplasty Demonstrate No Clinical or Radiological Differences at One Year.

INTRODUCTION: A successful outcome after total knee arthroplasty (TKA) includes the restoration of patello-femoral function. Modern patella component designs in TKA include a medialized dome and more recently, an anatomic design. There is a paucity of literature comparing these two implants.

METHODS: This prospective non-randomised study examined 544 consecutive TKAs with patella resurfacing using a posterior-stabilized, rotating platform knee prothesis performed by a single surgeon. A medialized dome patella design was used in the first 323 cases and an anatomic design in the subsequent 221 cases. Patients were assessed pre-operatively, at 4 weeks and 1-year post-TKA for Oxford Knee Score (OKS) (total, pain, and kneeling components) and range of movement (ROM). Radiolucent lines (RLL), patellar tilts and displacements, as well as re-operations were assessed at 1-year post-TKA.

RESULTS: At 1-year post-TKA, both groups demonstrated similar improvements in ROM, OKS, pain, and kneeling scores, and had a similar incidence of FFD (all P>0.05). Radiographically, there was no clinically significant difference in the incidence of RLLs, patellar tilts, and displacements. The prevalence of re-operations (1.8 versus 3.2%, P=0.526) was similar between the designs with no patella-related complications.

CONCLUSIONS: Both medialized dome and anatomic patella designs result in improved ROM and OKS with no patella-related complications. However, our study showed no differences between the designs at one year.