Background: Mobile-bearing knee designs represent an alternative to
conventional fixed-bearing total knee arthroplasty. We present the results of
a prospective, intermediate-term clinical follow-up study of the bicruciate
ligament-sacrificing porous-coated Low Contact Stress rotating-platform total
Methods: Between February 1984 and January 1994, 528 uncemented
primary knee replacements were performed in 421 patients. All patellae were
resurfaced with use of the Low Contact Stress rotating patellar component. The
average age of the patients at the time of the index procedure was sixty-nine
years. The study group included 261 women and 160 men. Patients were evaluated
at three months, six months, and yearly thereafter with use of the 100-point
New Jersey Orthopaedic Hospital knee-scoring system. In addition, a
radiographic analysis of the tibial, femoral, and patellar components was
performed at each interval.
Results: There were twenty-nine failures that resulted in revision.
The Kaplan-Meier estimate of implant survival at twelve years was 89.5% (95%
confidence interval, 83.4% to 95.6%). The total clinical scores improved
significantly compared with the preoperative scores for the first twelve
months postoperatively and then plateaued. Three hundred and twenty-one knees
had adequate radiographic follow-up (average, 8.1 years; range, five to twelve
years). Zonal radiographic analysis revealed ninety-three instances of
radiolucent lines (eighty-two of which measured <1 mm in width), with the
greatest number of radiolucent lines (thirty-nine) being located around the
tibial tray stem. None of these lines were deemed to be progressive, and no
knee with a radiolucent line that measured >2 mm was revised because of
Conclusions: This first-generation uncemented, mobile-bearing,
bicruciate ligament-sacrificing knee replacement was associated with a good
survival rate and demonstrated clinical efficacy during the five to
twelve-year follow-up interval.
Level of Evidence: Therapeutic study, Level IV (case
series [no, or historical, control group]). See Instructions to Authors for a
complete description of levels of evidence.