Postoperative alignment of total knee replacement. Its effect on survival

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Device Design

Background:

• Posterior cruciate condylar total knee arthroplasty (TKA) is a common procedure.
• Long-term implant survival is influenced by surgical technique, including prosthetic alignment.
• Understanding the impact of knee alignment on TKA outcomes is crucial for patient success.

Purpose of the Study:

• To evaluate the relationship between postoperative anatomic alignment and the long-term survival of posterior cruciate condylar total knee arthroplasties.
• To determine optimal alignment parameters for maximizing implant longevity.

Main Methods:

• Retrospective analysis of 421 posterior cruciate condylar TKAs performed between 1975 and 1983.
• Postoperative alignment was categorized into normal (5-8° valgus), varus (≤4° valgus to any varus), and valgus (>9° valgus) groups.
• Kaplan-Meier survival analysis was used to compare implant survival rates across alignment groups.

Main Results:

• Eight implant failures were observed: five in the varus group and three in the normal group.
• No failures occurred in the valgus group.
• Kaplan-Meier curves revealed a statistically significant difference in survival between the valgus and varus groups, and between the normal and varus groups.

Conclusions:

• Posterior cruciate condylar TKA survival is significantly lower in varus alignment compared to neutral or valgus alignment.
• Aligning the total knee prosthesis in neutral or slight anatomic valgus is recommended to improve long-term implant survival.
• Avoiding varus alignment is critical for successful posterior cruciate condylar total knee arthroplasty outcomes.