Two-Dimensional Preoperative Digital Templating is Less Accurate When Using a Collared Triple Taper Stem Versus a...

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Collared Triple Taper Stems (CTTS) and Single Taper Stems (STS) demonstrate excellent performance in primary total hip arthroplasty (THA).
• While 2D radiographic templating is accurate for STS, data for CTTS accuracy is limited.
• The anatomical design of CTTS may impact templating precision.

Purpose of the Study:

• To compare the templating accuracy of CTTS against the predecessor STS in THA.
• To evaluate if the anteroposterior design of CTTS influences templating size prediction.
• To assess the reliability of digital templating for predicting final implant size for both stem types.

Main Methods:

• A comparative study of 106 THA cases using CTTS and 106 THA cases using STS.
• All procedures were performed by high-volume surgeons using stems from the same manufacturer and identical templating software.
• Medial-lateral profile and size range were consistent between the compared stems.

Main Results:

• Direct template-to-stem accuracy was lower for CTTS (36.8%) compared to STS (49.1%).
• CTTS implants were more frequently undersized (2+ sizes) compared to STS (10.4% vs 2.8%).
• Stem type was the sole predictor for implants being 2 or more sizes smaller than templated.

Conclusions:

• Conventional 2D templating accuracy for CTTS is inferior to STS, often overestimating required stem size.
• The frequent undersizing of CTTS suggests potential limitations of current templating methods.
• Bi-planar or 3D preoperative templating may offer improved accuracy for CTTS, particularly during the learning curve.