Patient-Specific Total Knees Demonstrate a Higher Manipulation Rate Compared to "Off-the-Shelf Implants"

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Arthroplasty research

Background:

• Patient-specific implants aim to improve total knee arthroplasty (TKA) outcomes over standard implants.
• Limited prospective data exists comparing patient-specific TKA with traditional designs.

Purpose of the Study:

• To prospectively compare manipulation rates and clinical outcomes of patient-specific TKAs versus off-the-shelf TKAs.
• To evaluate functional results and patient satisfaction at a minimum two-year follow-up.

Main Methods:

• Prospective evaluation of 21 patient-specific TKAs matched against 42 posterior-stabilized and 11 cruciate-retaining off-the-shelf TKAs.
• Assessment of postoperative range of motion, manipulation rates, patient satisfaction, and Knee Society Score (KSS) pain scores.
• Radiographic analysis to investigate causes of stiffness.

Main Results:

• Patient-specific TKAs exhibited significantly less postoperative range of motion than both control groups (P<0.01).
• 28.6% of patient-specific TKAs required manipulation for stiffness, compared to 0% in control groups.
• At two-year follow-up, patient-specific TKAs showed similar motion but worse satisfaction and KSS pain scores.

Conclusions:

• Patient-specific total knee replacements demonstrated inferior early functional outcomes and higher manipulation rates.
• Early manipulation is recommended for stiffness in patient-specific TKA cases.
• Further investigation is needed to understand the causes of stiffness and poor outcomes in patient-specific TKA.