Abstract
IntroductionIn absence of deformity or injury of the contralateral leg, the contralateral leg length is used to plan limb lengthening. Length variability on long-leg weight-bearing radiographs (LLR) can lead to inaccurate deformity correction. The aim of the study was to (1) examine the variability of the measured limb length on LLR and (2) to examine the influence of the position of the magnification device.Materials and methodsThe limb lengths of 38 patients during deformity correction with a taylor-spatial-frame were measured retrospectively on 7.3 ± 2.6 (4–13) LLR per patient. The measured length of the untreated limb between LLR were used to determine length variability between LLR in each patient. To answer the secondary aim, we took LLR from a 90 cm validation distance. A magnification device was placed in different positions: at the middle of the 90 cm distance (z-position), 5 cm anterior and 5 cm posterior from the z-position, at the bottom and top of the validation distance as well as 5 cm medial and 15 cm lateral from the z-position.ResultsThe measured length variability ranged within a patient from 10 to 50 mm. 76% of patients had a measured limb length difference of ≥ 2 cm between taken LLR. Compared to length measurement of the 90 cm test object with the magnification device in the z-position (90.1 cm), positioning the device 5 cm anterior led to smaller (88.6 cm) and 5 cm posterior led to larger measurements (91.7 cm). The measured length with the magnification device at the bottom, top, medial or lateral (90.4; 89.9; 90.2; 89.8 cm) to the object differed not relevantly.ConclusionsHigh variability of limb length between different LLR within one patient was observed. This can result from different positions of the magnification device in the sagittal plane. These small changes in positioning the device should be avoided to achieve accurate deformity correction and bone lengthening. This should be considered for all length and size measurements on radiographs.
Highlights
In absence of deformity or injury of the contralateral leg, the contralateral leg length is used to plan limb lengthening
The intra-individually measured limb length varied in all patients by at least 1 cm between long-leg weight-bearing radiographs (LLR). 25 (65.8%), 26 (68.4%), 26 (68.4%) and 29 (76.3%) patients had a variation of ≥ 2 cm between LLR
The measured limb length between LLR ranged between 11–43 mm, 12–50 mm, 10–42 mm and 10–47 mm within one patient
Summary
In absence of deformity or injury of the contralateral leg, the contralateral leg length is used to plan limb lengthening. Archives of Orthopaedic and Trauma Surgery setting, the TSF is an accurate treatment device to promote healing of complex nonunions with multiplanar deformities and significant mechanical axis deviation [11] In these patients, the contralateral uninjured leg is used as a reference to determine limb length discrepancies on LLR. Iterative adjustment of the bone transport and the deformity correction based on the control radiographs are often necessary until the desired mechanical axis alignment is achieved [11, 15] These adjustments are time-consuming, result in higher radiation exposure for the patient, increase treatment time of bone lengthening procedures with increasing risk of pin infections and lead to patient’s and doctor’s dissatisfaction. Studies and knowledge are limited regarding the variability of the measured limb length on LLR
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
