# Radiostereometric analysis for evaluating inducible fracture micromotion: a scoping review

## TL;DR

This scoping review maps clinical studies using radiostereometric analysis to assess inducible fracture micromotion, highlighting methodological diversity and potential for guiding future research.

## Contribution

The paper provides a comprehensive overview of RSA applications for inducible fracture micromotion, identifying gaps and guiding future standardization.

## Key findings

- Seven clinical studies were identified using RSA to assess inducible fracture micromotion across various fracture types.
- RSA consistently detected small-scale motion and, in some cases, distinguished between union and non-union.
- Methodological heterogeneity was observed, including varied loading protocols and small sample sizes.

## Abstract

Reliable assessment of fracture healing remains a clinical challenge as radiographs and clinical examination provide only indirect information. Inducible fracture micromotion, defined as fragment displacement under load, may offer a more direct surrogate for healing. Radiostereometric analysis (RSA) can measure micromotion with high precision, but its clinical use for fracture assessment remains limited and heterogeneous. This scoping review aimed to map the existing literature on RSA for inducible fracture micromotion and summarize methodological approaches to guide future research.

We systematically searched Medline, Embase, and Scopus. Clinical studies applying RSA to assess inducible fracture micromotion were eligible. 2 reviewers independently screened and extracted data on study design, patient population, fracture location, loading protocols, thresholds for motion, and outcomes.

7 clinical studies were included, comprising feasibility studies, prospective cohorts, and 1 imaging study. Sample sizes ranged from 6 to 16 patients, with fractures of the distal radius, femur, proximal tibia, and pelvis. All studies required intraoperative implantation of tantalum markers. Most applied differentially loaded RSA, typically comparing unloaded and loaded conditions using weightbearing platforms, force plates, or voluntary grip dynamometry. Despite varied protocols and small, single-center designs, RSA consistently detected small-scale inducible motion and, in some studies, distinguished union from non-union.

This scoping review identified 7 clinical studies using RSA to assess inducible fracture micromotion, with heterogeneous methods across fracture types. These findings may guide the development of standardized approaches and support future research on RSA in fracture healing.