Survivorship and Complications in Revision Total Knee Arthroplasty With a Constrained Condylar Knee Implant: A Minimum 10-Year Follow-Up Study.

BACKGROUND

Constrained condylar knee (CCK) prostheses are commonly utilized in revision total knee arthroplasty (rTKA) when additional constraint is needed due to ligamentous insufficiency. However, data on long-term outcomes remain limited. This study evaluated the survivorship and complications of CCK implants over a minimum 10-year follow-up, extending up to 23 years.

METHODS

We retrospectively analyzed 345 rTKA procedures with CCK implants performed between 2001 and 2014. The cohort included 190 women (55%) and 155 men (45%), with a mean age of 69 years (range, 36 to 92). The mean follow-up duration was 13.5 years (range, 10 to 23.3 years). The primary indication for initial TKA was osteoarthritis (81%). Revisions were performed for aseptic loosening (23.2%), infection (22.9%), malrotation/malalignment (14.2%), and instability (13%). Femoral augments were used in 238 cases, tibial augments in 62 cases, and void fillers for bone defects in 25 patients. Kaplan-Meier survival analysis assessed implant longevity, defining failure as revision for any cause and revision due to aseptic loosening.

RESULTS

Kaplan-Meier analysis demonstrated favorable long-term implant survivorship. All-cause revision-free survival was 95.1% (95% CI [confidence interval]: 92.7 to 97.5) at 5 years and 93.6% (95% CI: 91.0 to 96.2) from 10 years onward. Survival free from aseptic loosening was 98.5% (95% CI: 97.1 to 99.9) at 5 years and 97.9% (95% CI: 96.3 to 99.5) through 20 years. The number of knees at risk declined over time, from 314 at 10 years to 16 at 20 years. A total of 25 complications occurred at a mean of 2.9 years post-revision, with 22 requiring surgical intervention. The leading causes for re-revision were infection (54.5%) and aseptic loosening (31.8%).

CONCLUSIONS

The CCK implants demonstrate favorable long-term survivorship in rTKA at a minimum 10-year follow-up. These findings support the continued use of CCK implants in rTKA with appropriate patient selection and careful surgical technique.