The incidence of "forgotten" knees after PERSONA PS and Journey BCS 2, and determinants of its prevalence. A prospective 10-year controlled study eventually using single radius design as comparator.
Introduction and purpose
The results after primary TKA have traditionally been reported in terms of survivorship, functional outcome, or objective symptomatology.
Due to the ceiling-effect as well as the poor sensitivity of the commonly used just scoring scales, the research on contributing factors towards failure of success has been hampered since the introduction of TKA in medicine. At the same time, it has become increasingly clear that the success after TKA is only moderate, with approximately only 80% of patients achieving a satisfactory subjective outcome.
Most studies show that 20% of patients continue to be dissatisfied after TKA, and up to now any differentiating factors that might reduce this percentage have not been clearly identified. It is our belief that that the lack of adequate assessment tools is the main reason for this.
Recently however the "forgotten knee score" has been introduced, and in the meantime this score has also been validated in the Dutch language. Whereas traditional TKA research has been focused on comparing TKA designs based upon the comparison of average ceiling-type outcome scores, the purpose of this study is to compare the incidence of "forgotten" knees between different patient groups receiving the same implant Persona PS and Journey BCS 2, while, eventually, at the same time comparing them with another design (eg. single radius design).
600 patients receiving a Persona PS TKA and 600 patients receiving a Journey BCS 2 will be prospectively followed during 10 years, with standard clinical evaluation and radiologic follow-up, as well as calculation of their "forgotten" knee score on a 6-month, 1 year, 3 year, 5 year, and 10 year follow-up evaluation. As primary endpoints the "forgotten knee score" will serve as parameter, with objective clinical measures, Oxford Knee Score, SF12, WOMAC and American Knee Society Score as secondary endpoints. Clinical measures will be evaluated pre-op, 6 weeks, 6 months, 1 year and 3 years follow-up. Stratification will be based upon age group, gender, activity profile, previous surgery, and BMI. ANOVA and multiple regression analysis will be used for determination of potential differentiators and their significance, both for the primary and secondary endpoints.
A subgroup of patients undergoing TKA with a single radius design can be used as comparator, and will be analysed using the same primary and secondary endpoints.