Abstract
Summary
Revision TKA using CCK prosthesis showed comparable outcome to PS prosthesis in clinical and radiological results.
Introduction
In revision total knee arthroplasty (TKA), the goal should be to obtain good motion, function and most importantly stability. The stability depends on remaining soft tissue and implant design. The more the ligaments retain function, the less the implant constraint is needed to achieve stability. With increased constraint, the transfer of joint reaction forces to implant-bone interface may lead to mechanical loosening of the implant. Constrained condylar knee (CCK) prosthesis provides more constraint compared with posterior stabilized (PS) prosthesis. The purpose of this study was to compare the clinical, radiological outcome and survivorship of CCK and PS prosthesis in revision TKA.
Materials and Methods
One hundred and twenty-one consecutive revision TKAs using CCK (79 knees) and PS (42 knees) were included. The mean follow-up period was 63.2 months for CCK and 64.8 months for PS. The mean age was 69.5 years and 70.6 years in CCK and PS, respectively. Range of motion (ROM), American Knee Society (AKS) score, Hospital for Special Surgery (HSS) score, complications and failure rate were assessed. Radiographic measurements included tibiofemoral angle and radiolucent lines. The Kaplan-Meier survivorship analysis was performed with an end point of re-revision surgery for any reason and compared between CCK and PS using the Log-rank test.
Results
The mean range of motion improved from 97.5° to 115.9° in PS, from 89.5° to 110.1° in CCK. The mean Knee Society knee and functional scores improved from 47.6 and 36.4 to 89.7 and 66.1 with PS, from 53.5 and 41.7 to 79.2 and 66.8 with CCK. The mean Hospital for Special Surgery knee score also improved from 57 to 76.9 and 59.7 to 77.6, respectively. The complication rate was 7.5% (4 cases; 3 recurred infections, 1 instability) in PS and 10.3% (7 cases; 4 recurred infections, 1 periprosthetic fracture, 2 stem tip pains) in CCK. The Kaplan–Meier survivorship analysis revealed that ten year survival of the components was 85.4% for PS and 80.0% for CCK. In all aspects, there were no statistical difference (a p-value of more than 0.05) between PS and CCK.
Conclusion
Revision TKA using CCK prosthesis showed comparable outcome to PS prosthesis in clinical and radiological results. CCK prosthesis is a reliable and successful option for prosthesis selection in revision TKA when PS prosthesis is not enough for management of instability.
