Abstract
Cemented unicompartmental knee replacement (UKR) has been used for many years and has excellent results in many follow-up studies. However, concerns about the quality of fixation, cementing errors, and radiolucent lines have encouraged the development of cementless prostheses. Mobile bearing UKR are probably the ideal implants for cementless fixation as the loads at the interface tend to be compressive. Prior to the widespread introduction of cementless mobile bearing UKR three studies have been performed to assess this device. In a randomised radiostereometric (RSA) study the migration of cementless and cemented devices were the same in the second year suggesting the quality of fixation achieved was similar. A clinical randomised study demonstrated a dramatic reduction in radiolucent lines with cementless components compared to cemented and no difference in clinical outcome. A prospective cohort study of 1000 patients demonstrated no overall difference in complications or revision rate and identified no contraindications for cementless fixation. There are however anecdotal reports of occasional tibial plateau fracture and early subsidence of cementless components. Data from the National Registers would suggest that the revision rate with cementless is about half that compared to cemented however this difference may be because only experienced surgeons are using the cementless device.
Cementless mobile bearing UKR does seem to be a good evolutionary step in the development of UKR. It is important however that surgeons are trained in the use of the device and are careful with the technique.
