Related Experiment Video
Updated: Jun 6, 2026
An Efficient and Reproducible Protocol for Distraction Osteogenesis in a Rat Model Leading to a Functional Regenerated Femur
Published on: October 23, 2017
Subsidence of callotasis zone in distraction osteogenesis after external fixator removal, measured by RSA
Ragnhild B Gunderson1, Harald Steen, Joachim Horn
1Department of Radiology, Oslo University Hospital, Norway. ragnhild.gunderson@oslo-universitetssykehus.no
Background And Purpose:
In clinical practice, achieved lengthening of a callotasis zone should be maintained after the external fixator has been removed. The common understanding has been that the regenerated bone may subside. To investigate this, we used high-resolution radiostereometric analysis (RSA) with accurate measurement of the lengthening zone.
Patients And Methods:
We assessed the longitudinal subsidence of a callotasis zone after removal of the external fixator in distraction osteogenesis in 16 patients who underwent 17 segmental lengthening operations on the tibia (n = 9) or femur (n = 8). Median lengthening was 32 (6-80) mm. RSA was performed at the end of the consolidation period before the external fixation device was removed, and this was later repeated at a median time of 11 (4-32) weeks after frame removal.
Results:
A minimal median longitudinal change of 0.01 (-0.28 to 0.60) mm across the lengthening zone occurred in uncomplicated cases.
Interpretation:
Our results indicate that no subsidence of clinical interest occurs after external frame removal.
