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

BACKGROUND AND PURPOSE: 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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.