Short stems in total hip replacement: evidence on primary stability according to the stem type

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Implant design

Background:

• Increasing prevalence of total hip replacement in younger patients favors less invasive short stems.
• Clinical data beyond 10 years for short stems are limited to a few designs.
• Primary stability is crucial for short stem hip implants, influencing long-term outcomes.

Purpose of the Study:

• To systematically review literature on primary implant stability in short stems.
• To assess stability based on implant micromotion and stem subsidence.
• To evaluate stability according to a predefined short-stem classification system.

Main Methods:

• Systematic literature review.
• Analysis of mechanical in vitro studies on micromotion.
• Review of clinical studies on stem migration patterns.

Main Results:

• Few in vitro studies exist, primarily for type 2 short stems, showing results comparable to long-term successful stems.
• Clinical data on migration patterns are limited but suggest outcomes similar to standard stems for most short stems.
• Comparative studies are scarce, but existing data indicate comparable performance for many short stems.

Conclusions:

• Biomechanical and clinical studies show promising initial stability for short stems.
• Long-term clinical studies are essential to validate these findings.
• Current literature covers only a small fraction of available short stem implants.