Angulation and Translation Capabilities of a Minimized Orthopedic Hexapod Ortho-SUV Frame: An Experimental Study

Abstract

Introduction
Orthopedic hexapods demonstrated effectiveness and accuracy in deformity correction of limbs in both adults and children. 
Previous studies demonstrated the best reduction capabilities of the orthopedic hexapod Ortho-SUV Frame (OSF) versus other 
models of this group of external fixation devices. Minimized version of this hexapod (minimized Ortho-SUV Frame (OSFm)) 
was created to reduce common for this group disadvantages: large bulkiness and weight and limitation on working with “short 
segments”. However, the reduction capabilities of the OSFm have not yet been studied.
Aim
To evaluate translation and angulation capabilities of OSFm with standard struts size and to compare results to OSF with short 
struts size.
Materials and Methods
The experimental study was performed using plastic models of the tibia with osteotomy at the middle third of the shaft. Proximal 
and distal bone fragments were fixed with one-ring modules. The reduction capabilities of OSFm in the first series and OSF in the 
second series of the experiment were studied. According to the method of fixing the struts to the rings, experiments were divided 
into three groups: directly to the ring, using straight plates, and using Z-shaped plates. Translation and angulation capabilities were 
evaluated by the maximum displacement of the distal bone fragment relative to the proximal one until any of the struts reached 
its minimum or maximum possible length.
Results
In translation OSFm outperforms OSF by 2.8-9.5% fixed the struts directly to the rings, by 4.8-9.7% using straight plates, and by 
27.3-29.3% using Z-plates. In angulation OSFm with struts fixed directly to the rings outperforms OSF by 33.9-55.4%, by 36.9-
47.3% using straight plates, and by 29.6-36% using Z-plates.
Conclusion
OSFm exceeds OSF in translation and angulation capabilities in all series of experiment. Distraction and rotation capabilities and 
the bone fragments fixation rigidity should be evaluated as further research to prove application of OSFm as a possible better 
candidate for deformity correction of limbs in children and foot deformity correction.