No difference in anterior knee pain between a fixed and a mobile posterior stabilized total knee arthroplasty after 7.9 years

Purpose The presence of anterior knee pain remains one of the major complaints following total knee arthroplasty (TKA). Since the introduction of the mobile TKA, many studies have been performed and only a few show a slight advantage for the mobile. In our short-term follow-up study, we found less anterior knee pain in the posterior stabilized mobile knees compared to the posterior stabilized knees. The concept of self-alignment and the results from our short-term study led us to form the hypothesis that the posterior stabilized mobile knee leads to a lower incidence of anterior knee pain compared to the posterior stabilized fixed knee. This study was designed to see whether this difference remains after 7.9 years in the follow-up. A secondary line of enquiry was to see whether one was superior to the other regarding pain, function, quality of life and survival. Methods This current report is a 6–10-year (median 7.9 years) follow-up study of the remaining 69 patients with a cemented three-component TKA for osteoarthritis in a prospective, randomized, double-blinded clinical trial. Results In the posterior stabilized group, five of the 40 knees (13 %) versus five of the 29 posterior stabilized mobile group (17 %) experienced anterior knee pain. No differences were observed with regard to ROM, VAS, Oxford 12-item knee questionnaire, SF-36, HSS patella, Kujala or the AKSS score. Patients with anterior knee pain reported more pain, lower levels of the AKSS, HSS patella and the Kujala scores than the patients without anterior knee pain. Conclusion In the current clinical practice, the appearance of anterior knee pain persists as a problem; simply changing to a mobile bearing does not seem to be the solution. The posterior stabilized mobile total knee did not sustain the advantage of less anterior knee pain, compared with the posterior stabilized fixed total knee arthroplasty. Level of evidence Therapeutic study, Level II.