Limb alignment in computer-assisted minimally-invasive unicompartmental knee replacement.

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Medical Imaging

Background:

• Medial unicompartmental knee arthroplasty (UKA) aims to restore natural limb alignment.
• Accurate post-operative alignment is crucial for UKA success and longevity.
• Conventional instrumentation may introduce variability in achieving planned alignment.

Purpose of the Study:

• To compare the accuracy of computer-assisted surgery (CAS) versus conventional instrumentation in achieving planned post-operative alignment during simultaneous bilateral medial UKA.
• To evaluate the impact of CAS on lower limb alignment accuracy in medial UKA.

Main Methods:

• Twenty patients underwent simultaneous bilateral medial UKA.
• Pre-operative planning of limb alignment was performed using hip-knee-ankle alignment and valgus stress radiographs.
• One knee was operated on using conventional instrumentation, while the contralateral knee used CAS, with randomized side and order.
• Post-operative alignment was compared to the pre-operative plan for both techniques.

Main Results:

• The mean variation between planned and achieved alignment was significantly lower with CAS (0.9 degrees) compared to conventional methods (2.8 degrees) (p < 0.001).
• 87% of navigated limbs achieved alignment within +/- 2 degrees of the plan, versus 60% for non-navigated limbs.
• CAS demonstrated a statistically significant improvement in the accuracy of lower limb alignment correction.

Conclusions:

• Computer-assisted surgery significantly enhances the accuracy of post-operative lower limb alignment in medial unicompartmental knee arthroplasty.
• Improved alignment accuracy with CAS may lead to better functional outcomes and increased implant survival rates.
• CAS offers a valuable advantage over conventional techniques for precise alignment in bilateral UKA procedures.