A Retrospective Comparative Study of Ultrasound-guided Extramedullary Kinematic Alignmentin Total Knee Replacement

Area of Science:

• Orthopedic Surgery
• Medical Imaging
• Biomechanical Engineering

Background:

• Accurate hip-knee-ankle (HKA) alignment is critical for total knee replacement (TKR) success.
• Kinematic alignment (KA) aims to restore natural joint anatomy for better patient outcomes.
• Ultrasound offers noninvasive, real-time identification of the femoral head center (COFH) to improve surgical accuracy.

Purpose of the Study:

• To evaluate if ultrasound-guided COFH identification enhances postoperative HKA alignment accuracy in KA-based TKR.
• To compare alignment outcomes between ultrasound-guided and conventional calipered TKR procedures.

Main Methods:

• Retrospective analysis of 217 primary TKR patients (2020-2022).
• Patients divided into calipered (no ultrasound) and ultrasound-guided COFH identification groups.
• Postoperative HKA angles assessed via radiographic measurements and statistical analysis.

Main Results:

• The ultrasound-guided group achieved significantly better HKA alignment (91.6% within safe range) versus the calipered group (81.1%, p=0.029).
• Ultrasound guidance reduced the risk of postoperative varus/valgus crossover by 59%.
• Improved alignment precision was noted, especially in neutral-type osteoarthritis knees.

Conclusions:

• Ultrasound-guided COFH identification is a valuable tool for improving HKA alignment accuracy in KA-based TKR.
• This noninvasive, real-time technique enhances surgical precision and potentially clinical outcomes.
• The method is particularly beneficial for neutral-type osteoarthritis knees.