The clinical history of mobile-bearing patella components in total knee arthroplasty.

Two hundred fifty-six primary cementless meniscal-bearing total knee arthroplasties were performed between May 1985 and January 1989. All knees were replaced with a low contact stress metal-backed anatomic mobile patella. The average patient follow-up was 11.5 years. No patellae were revised for failure of fixation and no dislocations or subluxations were reported. One patella was revised for polyethylene wear, and one well-functioning component was removed at the time of revision to facilitate range of motion and wound closure. The survival estimate at 12 years was 99.5%. Compared to the high incidence of failure of metal-backed fixed-bearing patellae components, the anatomic rotating patella provides durable long-term results with a low incidence of complications.

The long-term results of a metal-backed mobile bearing patella.

UNLABELLED: Enthusiasm for metal-backed patella has waned because of the high incidence of complications. Considering that perhaps all metal-backed patellae may not be the same, 256 primary consecutive metal-backed mobile bearing TKAs done between May 1985 and January 1989 were retrospectively reviewed to evaluate the results of a unique mobile bearing metal-backed patella. There were four complications (1.6%). Three patella were revised for polyethylene complications and one well-functioning component was removed at the time of revision of the tibial polyethylene to facilitate range of motion and wound closure. No patella was revised for loosening, subluxation, or dislocation. Our results show that all metal-backed patella are not the same and that compared with the high incidence of failure of fixed bearing metal-backed patellae, the use of the anatomic mobile bearing metal-backed patella can produce excellent, durable long-term clinical and radiographic results with a low incidence (1.6%) of complications. Life table survivorship using revision for any reason as the end point was 97% (95% confidence interval, 93%-100%) at a maximum of 19 years. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series--no, or historical control group). See the Guidelines for Authors for a complete description of levels of evidence.