A tibial implant comprising: a baseplate having a bone contacting surface, a bearing support surface and a proximally extending wall at least partially surrounding the bearing support surface a bearing component slidably mounted with respect to the baseplate bearing support surface, the bearing component having a proximally facing condylar surface and a distally facing surface for contacting the baseplate bearing support surface the proximally and distally facing bearing component surfaces spaced to define a circumferential side surface therebetween and an elastic gasket element interposed within a gap formed between the baseplate proximally extending wall and the bearing component circumferential side surface.
