Study Of The Therapeutic Effect Of Condylar Constrained Knee Prosthesis In Revision And Complex Primary Total Knee Arthroplasty

Objective:To investigate the application and therapeutic effect of condylar constrained knee prosthesis used in revision and complex primary total knee arthroplasty.Methods:From June 2003 to October 2014,47 patients who underwent revision and primary total knee arthroplasty (31 were primary TKA and 16 revision TKA) using condylar constrained knee prosthesis were retrospectively analyzed, including 15 males and 32 females, aged 43 to 87 years (mean age 65.4 years). In the primary group, there were 10 patients suffering from severe valgus deformity,9 suffering from severe varus deformity and 8 with serious bone defects while among the revision patients 9 cases suffering from aseptic prosthesis loosening,7 with chronic infection and 3 with serious bone defects (classified as type Ⅱ、Ⅲ according to the AORI classification).The follow-up was conducted at 3 days、1、6 and 12 months postoperatively and later annually. We used the ROM (Range Of Motion), HSS Score (Hospital of Special Surgery) KSKS Score (American Knee Society Knee Score) and KSFS Score (American Knee Society Function Score) to evaluate the pre-operational and post-operational status of knee.Results:All the 47 patients were well followed up for a mean period of 5.5 years (2 to 12 years).The ROM increased from 81.4 ± 15.2 pre-operationally to 90.9 ± 15.9 post-operationally. Similarly the HSS score improved from 51.1 ± 15.0 to 85.3 ± 8.4. The KSKS Score improved from 26.1 ± 13.2 to 80.1 ± 12.2. The KSFS Score improved from 40.0 ± 14.9 to 85.9 ± 9.3. It turned out that there were significant differences between pre-operational and post-operational figures (P<0.05). Two complications (infection) were observed (one in the revision patients and the other in the primary patients). No other complications occurred during the follow-up period such as instability、prosthesis loosening and deep vein thrombosis.Conclusion:The condylar constrained knee prosthesis plays an important role in revision and complex primary total knee arthroplasty, especially for patients faced with the injury of collateral ligaments、severe valgus deformity and bone defects. Combined with metal augmentation and intramedullary stem, condylar constrained knee prosthesis can correct the component alignment, balance the flexion and extension gap and assure the stability of prosthesis. In our investigation, the short-term outcome has proved satisfying. Still, further study and long-term follow-up are needed.