Abstract
Initial design cementless metal-backed patellar implants failed due to multiple reasons
including implant design, use of first-generation polyethylene, and surgical technique.
This study evaluates clinical outcomes and survivorship of total knee arthroplasty
(TKA) using a current generation highly porous metal-backed patellar component. One-hundred
twenty-five consecutive primary cementless TKAs with a compression molded highly porous
metal-backed patella were reviewed. One-hundred three TKAs (82.4%) with 5-year clinical
and radiographic follow-up were available for review. These were matched with 103
consecutive TKAs using a cemented patella of the same implant design. The cementless
cohort had a mean age of 65.5 years, body mass index (BMI) of 33.0, and follow-up
of 64.4 months. Indications for cementless TKA were based on multiple factors including
age, BMI, and bone quality. There were no revisions for loosening or mechanical failure
of the cementless patella compared with two cemented patellae revised for aseptic
loosening. Eight patients required revisions in the cementless cohort: three for prosthetic
joint infection (PJI), two for instability, one periprosthetic femur fracture, one
for patella instability, and one for extensor mechanism rupture. Five patients required
revisions in the cemented cohort: two for aseptic patellar loosening, one for aseptic
femoral loosening, one for PJI, and one for instability. All-cause survivorship at
5 years was 92.2 and 95.1% for the cementless metal-backed implant and cemented implant
cohorts, respectively. Use of a compression molded highly porous metal-backed patella
component demonstrated excellent clinical and radiographic results at 5-year follow-up.
Longer follow-up is required to evaluate the ability of highly porous cementless patella
implants to provide durable long-term fixation.
Keywords
cementless TKA - cementless patella - outcomes - complications - survivorship
