Comparative experience with intramedullary and extramedullary alignment in total knee arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Total knee arthroplasty (TKA) aims to restore joint function and alignment.
• Accurate component placement is crucial for TKA success and longevity.
• Intramedullary (IM) and extramedullary (EM) alignment techniques are commonly used in TKA.

Purpose of the Study:

• To compare the accuracy of intramedullary versus extramedullary alignment in TKA.
• To evaluate the effect of alignment technique on component positioning.
• To assess the achievement of optimal tibiofemoral angle post-TKA.

Main Methods:

• Comparative analysis of 72 consecutive TKAs using the Moreland Knee Instrument System.
• Measurements from full-length anteroposterior radiographs taken 3 months post-operation.
• Assessment of femoral component valgus and tibiofemoral angle for both IM and EM alignment groups.

Main Results:

• Intramedullary alignment achieved correct femoral component valgus in 87.5% of cases, versus 68.8% for extramedullary.
• A correct tibiofemoral angle was achieved in 88% of IM aligned patients compared to 73% of EM aligned patients.
• The difference in alignment accuracy between IM and EM techniques was statistically significant (P < .1).

Conclusions:

• Intramedullary alignment demonstrates superior accuracy in achieving desired femoral component valgus in TKA.
• The intramedullary technique is associated with a higher rate of correct tibiofemoral angle.
• These findings support the use of intramedullary alignment for improved precision in total knee arthroplasty.