Can CT-based patient-matched instrumentation achieve consistent rotational alignment in knee arthroplasty?

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Medical imaging

Background:

• Accurate implant alignment is crucial for the long-term success of total knee replacements.
• Rotational alignment of the femoral component is a key factor in achieving optimal surgical outcomes.

Purpose of the Study:

• To evaluate the accuracy of specimen-matched cutting blocks derived from computed tomography (CT) scans for achieving precise rotational alignment of the femoral component in total knee arthroplasty.
• To assess the reliability of CT-based cutting blocks in orthopedic surgery.

Main Methods:

• CT scans of five fresh frozen full leg cadaver specimens were utilized.
• Specimen-matched femoral cutting blocks were designed and fabricated based on CT data.
• Bone cuts were performed using these blocks to implant a bi-compartmental femoral component.
• Rotational alignment was measured using an optical system and compared to CT-derived reference axes.

Main Results:

• The average rotational alignment achieved with CT-based cutting blocks was 1.9° (range 0°-6.3°).
• One specimen exhibited significant deviation, correlating with a degraded medial articular surface.
• The study demonstrated good rotational alignment accuracy in most specimens.

Conclusions:

• CT-based, specimen-matched cutting blocks offer a viable method for achieving accurate rotational alignment in total knee replacement surgery.
• For cases with significant cartilage degeneration, imaging techniques that better visualize cartilage may enhance cutting block design and fit.
• Further research into advanced imaging for surgical planning is warranted.