Posted on Sep 24, 2017, 3:27 pm
#1
I was reading a research paper on the precision of the PRECISE nail from 2014 by Yatin M. Kirane, MBBS, DOrtho, PhD, Austin T. Fragomen, MD, and S. Robert Rozbruch, MD. (Link to research paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4397804/)
One of the sections of the study was the resulting bone alignment.
It shows that unintentional changes in femoral and tibial alignment during lengthening happen with a few degrees.
In patients who did not undergo correction of a varus or valgus deformity, there was an unintentional +2° change in lateral distal femoral angle and a +3° change in medial proximal tibial angle, while the unintentional lateral shift in the mechanical axis deviation was 1 mm and 5 mm during femoral and tibial lengthening, respectively (Table 4). Among patients without any procurvatum/recurvatum deformity correction, the unintentional change in the sagittal plane angle was +3º for the femur and 0º for the tibia. A tendency for varus-procurvatum malalignment after proximal femur osteotomies and valgus-procurvatum malalignment after tibia osteotomies was observed. We attempted to minimize malalignment by selecting appropriate osteotomy level, by ensuring adequate length of the thicker nail piece beyond the osteotomy, and by using blocking screws [25] whenever indicated. One of the sections of the study was the resulting bone alignment.
It shows that unintentional changes in femoral and tibial alignment during lengthening happen with a few degrees.
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Note that when the numbers they are talking about are averages. So when they say 0º for the tibia, it is due to a range from -5º to +4º, the ranges are shown in table 4:
Note that these are small malalignments compared to other devices:
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