Elizabeth A. Szalay

The relationship between fractures and DXA measures of BMD in the distal femur of children and adolescents with cerebral palsy or muscular dystrophy

Children with limited or no ability to ambulate frequently sustain fragility fractures. Joint contractures, scoliosis, hip dysplasia, and metallic implants often prevent reliable measures of bone mineral density (BMD) in the proximal femur and lumbar spine, where BMD is commonly measured. Further, the relevance of lumbar spine BMD to fracture risk in this population is questionable. In an effort to obtain bone density measures that are both technically feasible and clinically relevant, a technique was developed involving dual‐energy X‐ray absorptiometry (DXA) measures of the distal femur projected in the lateral plane. The purpose of this study is to test the hypothesis that these new measures of BMD correlate with fractures in children with limited or no ability to ambulate. The relationship between distal femur BMD Z‐scores and fracture history was assessed in a cross‐sectional study of 619 children aged 6 to 18 years with muscular dystrophy or moderate to severe cerebral palsy compiled from eight centers. There was a strong correlation between fracture history and BMD Z‐scores in the distal femur; 35% to 42% of those with BMD Z‐scores less than −5 had fractured compared with 13% to 15% of those with BMD Z‐scores greater than −1. Risk ratios were 1.06 to 1.15 (95% confidence interval 1.04–1.22), meaning a 6% to 15% increased risk of fracture with each 1.0 decrease in BMD Z‐score. In clinical practice, DXA measure of BMD in the distal femur is the technique of choice for the assessment of children with impaired mobility.

Physeal Stapling Versus 8-plate Hemiepiphysiodesis for Guided Correction of Angular Deformity about the Knee

Background Angular deformity in the lower extremities results in cosmetic deformity, gait disturbance, pain, and early joint degeneration. Corrective osteotomy is the gold standard for angular deformity, but is a major surgical intervention with significant incidence of complication. For these reasons, hemiepiphysiodesis is an attractive alternative in the growing child to allow “guided growth” to correct the angular deformity. Physeal stapling has proven success, but hardware prominence or failure has been problematic. Recently, the tension band plate construct (“8-plate”) has been promoted for hemiepiphysiodesis, citing ease of surgical technique and more rapid rate of correction. We sought to test the claim that the 8-plate effected a more rapid correction of angular deformity with a lower complication rate. Methods Hemiepiphysiodesis for angular deformity in 63 lower extremities from 2000 to 2007 were retrospectively reviewed. Thirty-nine limbs received staple hemiepiphysiodesis and 24 received 8-plate hemiepiphysiodesis. Angular measurements were compared preoperatively, during the first year postoperatively, and at the time of hardware removal or skeletal maturity. Complications requiring additional surgery for the correction of angular deformity were noted in each group. Results There was no difference between the 2 groups in the rate of correction (∼10 degrees/y, P=0.48). Complication rates were similar (12.8% vs. 12.5%, P=1.0). Patients with abnormal physes (eg, Blount disease, skeletal dysplasias) had a higher complication rate (27.8% vs. 6.7% for patients with normal physes, P=0.04) with no difference between the 8-plate and staple groups (P=1.0). The patients in the 8-plate group were significantly younger than those in the staple group (P=0.04). Conclusions The 8-plate is as effective as staple hemiepiphysiodesis for guided correction of angular deformity with respect to rate of correction and complications, even in somewhat younger patients. Higher complication rates are observed in patients with pathologic physes. Level of Evidence Therapeutic—level III retrospective comparative study.

Effect of Cultural Factors on Outcome of Ponseti Treatment of Clubfeet in Rural America

BACKGROUND Nonoperative management of clubfoot with the Ponseti method has proven to be effective, and it is the accepted initial form of treatment. Although several studies have shown that problems with compliance with the brace protocol are principally responsible for recurrence, no distinction has been made with regard to whether the distance from the site of care affects the early recurrence rate. We compared early recurrence after Ponseti treatment between rural and urban ethnically diverse North American populations to analyze whether distance from the site of care affects compliance and whether certain patient demographic characteristics predict recurrence. METHODS One hundred consecutive infants with a total of 138 clubfeet treated with the Ponseti method were followed prospectively for at least two years from the beginning of treatment. Early recurrence, defined as the need for subsequent cast treatment or surgical treatment, and compliance, defined as strict adherence to the brace protocol described by Ponseti, were analyzed with respect to the distance from the site of care, age at presentation, number of casts needed for the initial correction, need for tenotomy, and family demographic variables. RESULTS Of eighteen infants from a rural area who had early recurrence, fourteen were Native American. The families of these children, like those of all of the children with early recurrence, discontinued orthotic use earlier than was recommended by the physician. Discontinuation of orthotic use was related to recurrence, with an odds ratio of 120 (p < 0.0001), in patients living in a rural area. Native American ethnicity, unmarried parents, public or no insurance, parental education at the high-school level or less, and a family income of less than

Children with Spina Bifida are at Risk for Low Bone Density

20,000 were also significant risk factors for recurrence in patients living in a rural area. Intrinsic factors of the clubfoot deformity were not correlated with recurrence or discontinuation of bracing. CONCLUSIONS Compliance with the orthotic regimen after cast treatment is imperative for the Ponseti method to succeed. The striking difference in outcome in rural Native American patients as compared with the outcomes in urban Native American patients and children of other ethnicities suggests particular problems in communicating to families in this subpopulation the importance of bracing to maintain correction. An examination of communication styles suggested that these communication failures may be culturally related.

A New Look at the Incidence of Slipped Capital Femoral Epiphysis in New Mexico

BackgroundPatients with spina bifida frequently sustain lower extremity fractures which may be difficult to diagnose because they feel little or no pain, although the relative contributions of low bone density to pain insensitivity are unclear. Routine dual-energy xray absorptiometry (DXA) scanning is unreliable because these patients lack bony elements in the spine, and many have joint contractures and/or implanted hardware.Questions/purposesWe asked (1) if the lateral distal femoral scan is useful in spina bifida; (2) whether nonambulatory children with spina bifida exhibit differences in bone mineral density (BMD) compared with an age-and-sex-matched population; and (3) whether Z-scores were related to extremity fracture incidence.MethodsWe retrospectively reviewed 37 patients with spina bifida who had DXA scans and sufficient data. Z-scores were correlated with functional level, ambulatory status, body mass index, and fracture history.ResultsThe distal femoral scan could be performed in subjects for whom total body and/or lumbar scans could not be performed accurately. Twenty-four of 37 had Z-scores below −2 SD, defined as “low bone density for age.” Ten of 35 patients (29%) with fracture information had experienced one or more fractures. Our sample size was too small to correlate Z-score with fracture.ConclusionWe believe BMD should be monitored in patients with spina bifida; nonambulatory patients with spina bifida and those with other risk factors are more likely to have low bone density for age than unaffected individuals. The LDF scan was useful in this population in whom lumbar and total body scans are often invalidated by contracture or artifact. Although lower extremity fractures occur regardless of ambulation or bone density, knowing an individual’s bone health status may lead to interventions to improve bone health.

Adolescents with Idiopathic Scoliosis are Not Osteoporotic

Purpose: Past epidemiological studies demonstrated a nearly fivefold lower incidence of slipped capital femoral epiphysis (SCFE) in New Mexico compared with Connecticut. A recent study demonstrated some regional variability but did not address this earlier finding. We sought to reexamine the incidence of SCFE in New Mexico to improve the understanding of the epidemiology and ultimately the disorder itself. Methods: The discharge databases for the 11 major medical centers in the state were reviewed for the ICD-9 code for SCFE (732.2) for 1995 to 2006. The data were analyzed by comparison with the 2000 New Mexico census data. The incidence data are reported as cases per 100,000 boys aged 10 to 17 years and girls aged 8 to 15 years, as per Kelseys original article. Results: The incidence of SCFE in New Mexico for the study period was 5.99. This is a doubling of the reported incidence in the 1960s (2.13) and represents a statistically significant change (P < 0.001). More detailed analysis of our data demonstrated a statistically significant increase during 3-year intervals: 1995-1997, 2.27; 1998-2000, 2.75; 2001-2003, 4.73; and 2004-2006, 7.38. The mean age of onset was 12.2 years. There was a male to female ratio of incidence of 1.94:1. Relative frequencies by race were as follows: 4.63x for African Americans, 2.20x for Hispanics, and 2.20x for Native Americans. A preponderance of cases was treated at the states only tertiary pediatric orthopaedic center: 168 to 15 in the remaining 10 centers. Conclusions: The incidence of SCFE has increased dramatically in New Mexico since Kelseys epidemiological study in 1970. Obesity is a patient factor that has changed over this same period. According to the National Health and Nutrition Examination Survey Data for 2003/2004, the rates of obesity have tripled since 1971. In New Mexico, 25% of high-school children are estimated to be overweight. However, according to a recent study examining a national database (compiled from 27 states), the national incidence of SCFE remained fairly constant at 10.8 per 100,000. Interestingly, as more patients are seen at a tertiary center for childrens orthopaedics, the rate of diagnosis in New Mexico has risen to resemble national trends. In the 1960, that center was located in a remote site and did not provide acute care for childrens musculoskeletal issues. Increased obesity in children and improved access to pediatric orthopaedic evaluation may have contributed to a significant increase in reported incidence of SCFE in New Mexico. Level IV Evidence.

Quantifying postoperative bone loss in children.

Study Design. Case controlled study. Objective. To explore the relative effects of body mass index (BMI) and the presence or absence of adolescent idiopathic scoliosis (AIS) on bone mineral density (BMD) as evidenced by Z-scores in adolescents. Summary of Background Data. Prior studies have identified adolescents with idiopathic scoliosis as having “osteoporosis” or “osteopenia,” when only a small percentage of subjects in these studies actually had bone density that was clinically abnormal. The terms osteoporosis and osteopenia as used in adults cannot be applied to adolescents and children, as fracture risk has not been well correlated to Z-scores. As we had noted that our scoliosis patients of normal and heavy weight had normal Z-scores, this study was undertaken to explore the relationship of bone mineral density to body mass index in adolescents with and without scoliosis. Methods. Dual energy x-ray absorptiometry (DXA) scans of 49 adolescents with adolescent idiopathic scoliosis were compared to 40 normal control adolescents. Z-scores were compared to reduce variability when comparing subjects of varying age and genders. Student t test or simple linear regression was used to explore relationships between Z-scores and clinical and demographic variables. Results. In both groups of subjects, Z-score was most strongly correlated with BMI (P < 0.001). The presence of scoliosis had the effect of lowering the Z-score as if the individual had “lost” 3.4 BMI units. Conclusion. Z-scores in subjects with and without scoliosis were most strongly correlated to BMI: thin patients had lower bone density, heavy patients had higher. The presence of scoliosis had an effect similar to subtracting 3.4 “BMI units,” lowering the Z-score from what might otherwise be predicted. The “scoliosis effect” may be noticeable in thin individuals, pushing them to the “low for age” level, whereas in heavier individuals, the effect is negligible. No subjects in either group met the ISCD definition for osteoporosis.

Magnetic resonance imaging in the diagnosis of childhood discitis.

Background: Postoperative bone density loss is an accepted phenomenon that has not been objectively quantified. The extent of this bone loss is documented using preoperative and postoperative dual energy x-ray absorptiometry scans to demonstrate the magnitude of the problem and to underline the need for prevention and treatment. Methods: Children undergoing lower extremity surgery who required a minimum of 4 weeks of either non-weight bearing or cast immobilization postoperatively were recruited to undergo preoperative and postoperative dual energy x-ray absorptiometry scans of lumbar spine and both distal femora. Percent change in bone mineral density (BMD) as well as Z-scores in preoperative and postoperative scans were compared, as were operated and nonoperated limbs, using paired t tests. Results: Fifteen of 18 subjects completed the second scan. Children lost up to 34% BMD in the cancellous region of the operated leg (average, 16.5%), up to 28% in transitional bone (average, 11.5%), and up to 16% (average, 4.8%) in the cortical region (P < 0.05). The Z-scores fell 1.0 SD for cancellous, 0.75 transitional, and 0.45 cortical. Conclusions: That children can lose up to 34% of BMD in 4 to 6 weeks is sobering. A 1 SD drop in T score, in adults, can infer a 2-fold increase in fracture risk. This may be insignificant in a healthy child with good BMD, but to a chronically ill child, a doubling of fracture risk may lead to insufficiency fracture. Avoiding the problem and proactive treatment are the goals. Level of Evidence: Level I, prospective diagnostic study.

Pediatric vitamin D deficiency in a southwestern luminous climate.

Diagnosis of disc space infection in childhood is often delayed and is usually made on the basis of multiple roentgenographic, laboratory, and nuclear imaging studies. Four cases of septic discitis in children are described. Special emphasis is placed on the diagnostic findings with magnetic resonance imaging. Magnetic resonance sensitivity for this entity and its role in comparison with other imaging modalities are discussed.

Bone mineral density correlation with fractures in nonambulatory pediatric patients.

Background Few studies look at vitamin D levels in children living in sunny climates as it is assumed that they receive adequate vitamin D from sun exposure. In light of changing lifestyles of children and studies documenting vitamin D deficiency among children in extreme climates, a study to examine vitamin D levels in healthy children living in a luminous climate was conducted. Methods A retrospective chart review of vitamin D levels in healthy children with vague musculoskeletal pain (such as “growing pains”) was done. Healthy children, specifically without musculoskeletal pain, were prospectively recruited as controls. Results Eighty-eight children, 42 children with “pain” and 46 controls were studied. No statistical difference in vitamin D levels was found between the “pain” group (mean vitamin D level 29.1 ng/mL) and the control group (mean vitamin D level 32.4 ng/mL, P<0.52). Overall, 14% of the entire group had levels <20 ng/mL, 49% had levels <30 ng/mL, and 15% had levels >40 ng/mL. Conclusions A consensus has yet to be established as to what an “optimal” vitamin D level is for growing children to develop strong bones for a lifetime. This study demonstrated that 14% of children living in a sunny climate had vitamin D levels below 20 ng/mL, a level universally accepted as insufficient, and 49% were below 30 ng/mL, arguably a “desired” level. A sunny climate does not assure vitamin D sufficiency. Virtually all children should be supplemented, with laboratory follow-up for those at high risk for low bone density/those with insufficiency fractures. Level of Evidence Level III case-control study.