Satisfactory Short-Term Results of Navigation-Assisted Gap-Balancing Total Knee Arthroplasty Using Ultracongruent Insert

Abstract

Background The use of highly conforming ultracongruent (UC) polyethylene insert is bone-preserving and became a relatively common alternative to the conventional posterior stabilized total knee arthroplasty (TKA) design. The purpose of this study was to analyze the short-term clinical and radiologic results of UC insert TKA using the navigation-assisted gap-balancing technique.

Methods Two hundred thirty-three knees were operated with a mean follow-up period of 8.1 years (minimum of 5 years). Radiologic and clinical outcomes were assessed before operation and at latest follow-up using the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index score. For statistical analysis, paired sample t-test and analysis of variance were used. Significance was considered as P < .05.

Results According to the preoperative deformities (valgus, mild varus, and moderate varus), there were 23 cases (9.9%) of valgus deformity, 180 cases (77.3%) of mild varus deformity, and 30 cases (12.9%) of moderate varus deformity. Overall, the results at mean 8.1 years revealed an improvement in mean Knee Society Score (54 ± 12 to 92 ± 3) and mean Western Ontario and McMaster Universities Osteoarthritis Index scores (62 ± 14 to 17 ± 3). Overall, 220 of 233 cases (94.4%) were in neutral alignment (between −3° and +3°) at latest follow-up. There were no migrating or shifting prosthesis that should be considered as possible failure. There was 0% component revision rate.

Conclusion Navigation-assisted gap-balancing technique using UC insert TKA had satisfactory short-term outcome. Strict gap-balancing technique using the offset-type-force-controlled-spreader-system aided in the satisfactory results.