Do children with Blount disease have lower body mass index after lower limb realignment?

BACKGROUND: Children with Blount disease are typically obese. The goal of our study was to assess whether children with Blount disease had lower body mass index (BMI) after surgical correction of their lower limb deformity. METHODS: A surgical data base was used to identify children with Blount disease. Demographic information including age of disease onset, ethnicity, health insurance status, and laterality was noted. Preoperative and most recent BMI values were documented. Using full-length standing radiographs, the mechanical axis deviation (MAD) and leg length discrepancy (LLD) were measured preoperatively and at latest follow-up. The relationship of the change in BMI with various demographic and radiologic parameters was evaluated. RESULTS: Fifty-one children (32 males, 19 females) with Blount disease (23 early onset, 28 late onset) affecting 70 lower extremities (32 unilateral and 19 bilateral) underwent a variety of surgical procedures. All 47 children who underwent gradual correction with external fixation also underwent nutritional counseling while receiving inpatient rehabilitation. At an average follow-up of 48 months, MAD improved from 80.5 mm medial to 16.1 mm medial (P<0.0001) and LLD improved from 19.6 to 10.9 mm (P=0.0002). During the same time period, the BMI increased from 35 (95% confidence interval, 32-37) to 38 (95% confidence interval, 35-41; P=0.0006). Compared with their preoperative BMI, 76% of the children had an increase in their BMI at the latest follow-up. There was no association of the change in the patient's BMI with their age of disease onset, sex, ethnicity, health insurance status, final MAD, or LLD. There was a tendency for the patient's BMI to increase with longer follow-up (P=0.002). Using multivariate analysis, only the length of follow-up was associated with an increase in BMI (P=0.026). CONCLUSIONS: Despite improvement in limb alignment and LLD after surgery, the BMI of the majority of children with Blount disease increased over time. Other strategies for addressing obesity amongst these children are warranted. LEVEL OF EVIDENCE: Level IV--case series.

The effect of circular external fixation on limb alignment.

INTRODUCTION: A full-length standing radiograph of the entire lower extremity is the standard imaging modality for assessing lower limb alignment. However, the effect of an overlying circular external fixator on the radiographic alignment of the lower extremity is not well documented. METHODS: After correction of angular deformity using a circular external fixator, 29 patients (31 limbs) underwent 2 sets of full-length standing radiographs, one done before, and the other, after removal of the fixator. The difference in the measurement of frontal plane alignment, limb lengths, and rotation between the 2 radiographs was analyzed. RESULTS: The mean absolute difference in the measurement of mechanical axis deviation (MAD) between the 2 radiographs was 11.5 mm (P < 0.0001) for the ipsilateral limb (with the external fixator) and 8.9 mm (P < 0.0001) for the contralateral limb. The mean difference in the radiographic measurement of limb lengths was 20 mm (P < 0.0001) for the ipsilateral and 20.2 mm (P < 0.0001) for the contralateral limb. As the magnitude of MAD and external rotation of the ipsilateral limb increased, a progressive increase in the magnitude of discrepancy in the measurement of MAD between the 2 sets of radiographs was noted. There was no significant effect (P > 0.05) of the patient's age, sex, body mass index, primary diagnosis, duration between the 2 radiographs, and the direction of malalignment found on the discrepancy in the measurement of MAD for both limbs. CONCLUSIONS: The standing full-length radiograph with an overlying circular external fixator may not be a reliable indicator of limb alignment and length of the operated extremity. Moreover, the presence of the circular external fixator on the lower extremity can affect the alignment and length of the opposite limb. Clinicians using circular external fixators for lower extremity trauma and reconstruction should be aware of the pitfalls of using a full-length standing radiograph for assessing limb alignment and length during osseous healing. LEVEL OF EVIDENCE: Diagnostic level II.

Pediatric orthopaedic patients presenting to a university emergency department after visiting another emergency department: demographics and health insurance status.

BACKGROUND: The disparity in access to and delivery of health care among children has become increasingly apparent. The purpose of our study was to analyze demographic information, including health insurance status, of children with extremity injuries seen at a University Hospital emergency department (UH ED) after visiting another ED for the same complaint. METHODS: A database of pediatric orthopaedic consults requested for extremity injuries at UH ED was reviewed. Information regarding patients' age, ethnicity, orthopaedic diagnosis, type of health insurance, time from injury to presentation at the first ED and at UH ED, mode of transportation to UH ED, and orthopaedic treatment rendered was analyzed. All patients with Medicaid, health maintenance organization-Medicaid, no insurance, or charity care were classified as having public insurance, whereas those with commercial insurance, including health maintenance organization and preferred provider organization plans, were placed in the private insurance category. RESULTS: Over a 30-month period, 125 children, of whom 18% had private health insurance, were noted to have recently visited another ED seeking treatment for an extremity injury. A closed fracture was diagnosed in 117 patients, 94% of whom were discharged from UH ED after cast application. There was no difference with regard to patients' age, sex, ethnicity, diagnosis, and time to presentation at the initial ED between private and public insurance groups. However, 52% of children with private insurance received orthopaedic care within 24 hours compared with 22% with public insurance (P = 0.013). Children with public insurance were more likely to have visited another health facility besides the initial ED before presenting to UH ED (P = 0.004). Moreover, 74% of privately insured patients presenting to UH ED arrived via ambulance compared with 34% with public insurance (P < 0.001). CONCLUSIONS: Most children with an extremity injury who received orthopaedic consultation at a tertiary-level ED after visiting another ED had an isolated fracture requiring cast treatment only. There was a trend for delay in receiving definitive orthopaedic care for patients with public health insurance compared with those with private insurance.

Correlation of body mass index and radiographic deformities in children with Blount disease.

BACKGROUND: Children with Blount disease tend to be heavier than their peers; however, the relationship between the magnitude of obesity and the severity of limb deformities in Blount disease has not been well studied. METHODS: A retrospective review of the preoperative medical records and radiographs of patients with previously untreated Blount disease was conducted. Demographic information including gender, ethnicity, the age when deformity was first noted, the age at the examination, and the body mass index was recorded. Frontal and sagittal plane deformities were analyzed by one examiner using full-length standing radiographs. The association of body mass index with various demographic and deformity parameters was then analyzed. RESULTS: Over an eight-year period, forty-five patients with sixty-five limbs affected by Blount disease were identified. Seventeen children (twenty-seven limbs) had early-onset Blount disease, and twenty-eight children (thirty-eight limbs) had late-onset disease. Fifteen of the children with early-onset disease and twenty-six of those with late-onset disease were overweight. There was no significant relationship between body mass index and gender, ethnicity, or laterality. The children with early-onset disease tended to have a lower body mass index but a greater magnitude of radiographic deformities compared with the children with late-onset disease. Greater varus malalignment (r = 0.74, p < 0.0001) and tibial procurvatum (r = -0.79, p = 0.002) were noted with an increasing body mass index in the early-onset, but not the late-onset, group of patients. Irrespective of the age at onset, the correlation of body mass index with frontal and sagittal plane deformities was stronger in extremely obese children (body mass index of > or =40). CONCLUSIONS: There is a significant relationship between the magnitude of obesity and biplanar radiographic deformities in children with the early-onset form of Blount disease and in those with a body mass index of > or =40. These clinical findings are consistent with the literature concerning the effect of compressive forces on growth at the proximal tibial physis. LEVEL OF EVIDENCE: Prognostic Level II.

Computed radiographic measurement of limb-length discrepancy. Full-length standing anteroposterior radiograph compared with scanogram.

BACKGROUND: Although a scanogram is commonly used to measure limb-length discrepancy, there are several potential pitfalls associated with this imaging technique. The purpose of the present study was to evaluate the results obtained with use of a full-length standing anteroposterior radiograph of the lower extremities and to compare them with those obtained with use of a scanogram. Both imaging studies were performed using computed radiography. METHODS: One hundred and eleven patients with limb-length discrepancy had a full-length standing anteroposterior radiograph and a scanogram made on the same day. The patients included seventy-nine children and thirty-two adults in whom the discrepancy was secondary to trauma (55%), congenital shortening (18%), Blount disease (14%), or another cause (13%). Limb length and limb-length discrepancy were measured utilizing both imaging studies. The agreement between the standing anteroposterior radiograph and the scanogram was assessed with use of the correlation coefficient r, and the limits of agreement between the two imaging studies were assessed. RESULTS: An average magnification of 4.6% (3.3 cm) was observed in association with the measurement of lower extremity length with use of the full-length standing anteroposterior radiograph. The mean difference in limb-length-discrepancy measurements between the two techniques was 0.5 cm, and the limits of agreement (that is, the mean plus or minus two standard deviations) were 0.5 to 1.5 cm. When the limb-length discrepancy on the standing anteroposterior radiograph was compared with that on the scanogram, the correlation coefficient r was 0.96. A difference of >0.5 cm between the limb-length discrepancy measured on the standing radiograph and that measured on the scanogram was associated with a mechanical axis deviation of >2 cm. Remaining variables, including age, gender, etiology, and scanogram ruler inclination, did not correlate with a difference in the measurement of limb-length discrepancy with use of these two imaging studies. CONCLUSIONS: The measurement of limb-length discrepancy on a standing anteroposterior radiograph was very similar to that on a scanogram, especially in the absence of substantial mechanical axis deviation. These findings support the use of a standing anteroposterior radiograph of the lower extremities as the initial imaging study for patients presenting with unequal limb lengths. This approach allows for a more comprehensive radiographic evaluation of the lower extremity, including deformity analysis, while reducing the expense and radiation exposure as compared with the use of additional imaging studies for the assessment of limb-length discrepancy.