During limb lengthening over an intramedullary nail, decisions regarding external fixator removal and weightbearing depend on the amount of callus seen at the lengthening area on radiographs. However, this method is subjective and objective evaluation of the amount of callus likely would minimize nail or interlocking screw breakage and refracture after fixator removal. We asked how many cortices with full corticalization of the newly formed bone at the lengthening area are needed to allow fixator removal and full weightbearing and how to radiographically determine the stage of corticalization. We retrospectively reviewed 17 patients (34 lengthenings) who underwent bilateral tibial lengthenings over an intramedullary nail. The average gain in length was 7.2 ± 3.4 cm. We determined the pixel value ratio (ratio of pixel value of regenerate versus the mean pixel value of adjacent bone) of the lengthened area on radiographs. There were no nail or screw breakage and refracture. Partial weightbearing with crutches was permitted when the pixel value ratio was 1 in two cortices and full weightbearing without crutches was permitted when the pixel value ratio was 1 in three cortices. The pixel value ratio on radiographs can be an objective parameter for callus measurement and may provide guidelines for the timing of external fixator removal. We cannot determine from our limited data the minimum pixel value in how many cortices would suggest safe removal, but we can say our criteria were not associated with subsequent refracture.
Extensive limb lengthening may be indicated in achondroplastic patients who wish to achieve a height within the normal range for their population. However, increasing the magnitude of lengthening is associated with further complications particularly adjacent joint stiffness and fractures. We studied the relationship between the magnitude of femoral lengthening and callus pattern, adjacent joint stiffness and fracture of the regenerate bone in 40 femoral lengthenings in 20 achondroplastic patients. They were divided into two groups; group A had lengthening of less than 50% and group B of more than 50% of their initial femoral length. The patterns of radiological callus formation were classified according to shape, type and features. The incidence of callus features, knee stiffness and regenerate bone fracture were analysed in the two groups. Group B was associated with an increased incidence of concave, lateral and central callus shapes, adjacent joint and stiffness and fracture. Statistically, the incidence of stiffness in adjacent joints and regenerate bone fracture was significantly associated with the magnitude of lengthening. We suggest that careful radiological assessment of the patterns of callus formation is a useful method for the evaluation and monitoring of regenerate bone.
BackgroundChild with mild scoliosis is always a subject of interest for most orthopaedic surgeons regarding progression. Literature described Hueter-Volkmann theory regarding disc and vertebral wedging, and muscular imbalance for the progression of adolescent idiopathic scoliosis. However, many authors reported spontaneous resolution of curves also without any reason for that and the rate of resolution reported is almost 25%. Purpose of this study was to question the role of paraspinal muscle tuning/balancing mechanism, especially in patients with idiopathic scoliosis with early mild curve, for spontaneous regression or progression as well as changing pattern of curves.MethodsAn observational study of serial radiograms in 169 idiopathic scoliosis children (with minimum follow-up one year) was carried. All children with Cobb angle < 25° and who were diagnosed for the first time were selected. As a sign of immaturity at the time of diagnosis, all children had Risser sign 0. No treatment was given to entire study group. Children were divided in three groups at final follow-up: Group A, B and C as children with regression, no change and progression of their curves, respectively. Additionally changes in the pattern of curve were also noted.ResultsAverage age was 9.2 years at first visit and 10.11 years at final follow-up with an average follow-up of 21 months. 32.5% (55/169), 41.4% (70/169) and 26% (44/169) children exhibited regression, no change and progression in their curves, respectively. 46.1% of children (78/169) showed changing pattern of their curves during the follow-up visits before it settled down to final curve. Comparing final fate of curve with side of curve and number of curves it did not show any relationship (p > 0.05) in our study population.ConclusionPossible reason for changing patterns could be better explained by the tuning/balancing mechanism of spinal column that makes an effort to balance the spine and result into spontaneous regression or prevent further progression of curve. If this which we called as "tuning/balancing mechanism" fails, curve will ultimately progress.
The type of new bone formation seen on radiographs is related to clinical outcome, with homogeneous pathways being the most favourable ones.
A lucent pathway was seen in all fracture cases with concave, lateral, and atypical shapes, and there was more than 30% lengthening and 30% reduction of the callus width compared with the natural width of the femur, which are the warning signs for regenerate fractures. These signs help the surgeon to predict the outcome and guide him in planning for any additional interventions. The Ru Li classification is an effective method for the evaluation of the chance of callus fracture.
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