Radiographic accuracy in TKA with a CT-based patient-specific cutting block technique

Area of Science:

• Orthopaedic surgery
• Medical technology
• Radiology

Background:

• Patient-specific instrumentation (PSI) is gaining traction for total knee arthroplasty (TKA).
• Existing data on PSI's accuracy is debated within the orthopaedic community.
• This study investigates the radiological precision of CT-based PSI.

Purpose of the Study:

• To compare the radiological accuracy of CT-based patient-specific instrumentation (PSI) for total knee arthroplasty (TKA).
• To assess if PSI accuracy is similar to that of computer-navigated TKA reported in literature.

Main Methods:

• A consecutive series of 301 PSI TKAs (GMK MyKnee©) performed since 2010 were analyzed.
• Radiological assessment included preoperative and postoperative standard and long-standing X-rays.
• Postoperative analysis evaluated limb alignment and component positioning (varus/valgus, flexion, tibial slope).

Main Results:

• The average postoperative hip-knee-ankle angle was 180.1° ± 2.0°.
• Outliers >3° were observed in 12.4% for frontal plane alignment, 4.1% for tibial components, and 4.8% for femoral components.
• Component adaptation occurred intraoperatively in 10.8% of planned sizes.

Conclusions:

• CT-based PSI demonstrates radiological accuracy comparable to computer-assisted surgery for TKA.
• While the optimal limb axis for clinical outcomes remains under investigation, precise technology is crucial.
• PSI offers a precise method for achieving the intended surgical axis in TKA.