Gait analysis: An effective tool to mechanically monitor the bone regeneration of criticalsized defects in tissue engineering applications

Introduction
Tissue engineering has emerged as an innovative approach to treat critical-size bone
defects using biocompatible scaffolds, thus avoiding complex distraction surgeries or limited
stock grafts. Continuous regeneration monitoring is essential in critical-size cases due to the
frequent appearance of non-unions. This work evaluates the potential clinical use of gait
analysis for the mechanical assessment of a tissue engineering regeneration as an alternative
to the traditional and hardly conclusive manual or radiological follow-up.

Materials and methods
The 15-mm metatarsal fragment of eight female merino sheep was surgically replaced by a
bioceramic scaffold stabilized with an external fixator. Gait tests were performed weekly by
making the sheep walk on an instrumented gangway. The evolution of different kinematic
and dynamic parameters was analyzed for all the animal’s limbs, as well as asymmetries
between limbs. Finally, potential correlation in the recovery of the gait parameters was evaluated
through the linear regression models.

Results
After surgery, the operated limb has an altered way of carrying body weight while walking.
Its loading capacity was significantly reduced as the stance phases were shorter and less
impulsive. The non-operated limbs compensated for this mobility deficit. All parameters
were normalizing during the consolidation phase while the bone callus was simultaneously
mineralizing. The results also showed high levels of asymmetry between the operated limb
and its contralateral, which exceeded 150% when analyzing the impulse after surgery. Gait
recovery significantly correlated between symmetrical limbs.

Conclusions
Gait analysis was presented as an effective, low-cost tool capable of mechanically predicting
the regeneration of critical-size defects treated by tissue engineering, as comparing
regeneration processes or novel scaffolds. Despite the progressive normalization as the callus
mineralized, the bearing capacity reduction and the asymmetry of the operated limb
were more significant than in other orthopedic alternatives.