Posterior-stabilized total knee arthroplasty: a matched pair analysis of a classic and its evolutional design.
BACKGROUND
Total knee arthroplasty (TKA) designs continue to be modified to optimize patient's outcome. This study was designed to compare clinical and radiological results of classic worldwide used TKA posterior-stabilized (PS) design to those of its recent evolution.


METHODS
A consecutive group of 100 patients undergoing TKA using a classic cemented fixed-bearing PS TKA system was matched by age, gender, body max index to 100 patients having the newer cemented fixed-bearing PS design, both by the same manufacturer. Patients were assessed preoperatively, at 12 months and at 24 months minimum follow-up (range, 24-46) in a standard prospective fashion. The outcome assessments used were the Oxford Knee Score, the Knee Society Score, range of motion, and a satisfaction survey. A 2-samplettest comparing the 2 groups was performed.


RESULTS
No patients were lost at follow-up. At 2-year follow-up, differences in clinical and radiological Knee Society Score (P= .09), Oxford Score (P= .08), and overall satisfaction rate did not reach statistical significance. Implant group 2 showed a statistically significant decrease in postoperative anterior knee pain (P= .006). At final follow-up, 16% of group 1 knees achieved > 130° flexion compared with 37% in group 2 (P= .0009). There were 2 revisions for any reason in group 1 and none in group 2.


CONCLUSIONS
Design modifications applied to the newer TKA system allowed greater flexion and lower patellofemoral complications but did not appear to achieve better overall clinical scores.
Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA, USA.
Pier Francesco
PF
Indelli
Division of Orthopaedic Surgery, Villa Regina Hospital, Bologna, Italy; Faculty of Medical Sciences, Uniludes University, Lugano, Switzerland.
Gennaro
G
Pipino
Department of Orthopaedics and Rehabilitation, University of New Mexico School of Medicine, Albuquerque, NM, USA.
Paul
P
Johnson
Division of Orthopaedic Surgery, Umberto I Hospital, Enna, Italy.
Angelo
A
Graceffa
Department of Orthopaedic Surgery, Clinica Ortopedica Universita' di Firenze-CESAT, Firenze, Italy.
Massimiliano
M
Marcucci
Attune; Knee; Outcomes; Posterior-stabilized; TKA; Total knee arthroplasty