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

Abstract

Background: Constrained condylar knee (CCK) prostheses are commonly used in revision total knee arthroplasty (TKA) for cases requiring increased constraint due to ligamentous insufficiency. However, long-term outcomes remain underreported. 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 reviewed 345 revision TKA procedures with CCK implants performed from 2001 to 2014. The cohort included 190 women (55%) and 155 men (45%), with a mean age of 69 years (range, 36 to 92) and a mean follow-up of 13.5 years (range, 10 to 23.3). The primary diagnosis before initial TKA was osteoarthritis (81%). Indications for revision included aseptic loosening (23.2%), infection (22.9%), malrotation/malalignment (14.2%), and instability (13%). Femoral and tibial augments were used in 238 and 62 cases, respectively, while 25 patients required void fillers for bone defects. 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 survivorship. All-cause revision-free survival was 95.1% (95% CI [confidence interval]: 92.7 to 97.5) at five years and stabilized at 93.6% (95% CI: 91.0 to 96.2) from 10 years onward. Survivorship free from revision due to aseptic loosening was 98.5% (95% CI: 97.1 to 99.9) at five 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. There were 25 complications that occurred at a mean of 2.9 years post-revision, with 22 requiring surgical intervention. The most common causes for revision were infection (54.5%) and aseptic loosening (31.8%). Surgical management included revision TKA (n = 7), irrigation and debridement with polyethylene exchange (n = 4), two-stage revision (n = 3), and above-knee amputation (n = 2).

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