Bobby Kw Ng

A 10-year study of the changes in the pattern and treatment of 6,493 fractures.

A total of 6,493 fractures was studied from 6,389 children younger than 16 years admitted as inpatients to one center in a 10-year period. The boy-to-girl ratio increased from 1.4:1 in the infants to 4.9:1 in the adolescents. The most common fractures were the distal radius (20.2%), supracondylar fracture of the humerus (17.9%), forearm shaft (14.9%), and the tibial shaft (11.9%). A distinct age-specific fracture pattern also was found, with supracondylar fracture of the humerus being the most common fracture in the age 0- to 3-year (26.7%) and the 4- to 7-year (31.6%) groups and distal radius in the 8- to 11-year and the 12- to 16-year groups (24.3 and 25.7%, respectively). Although the overall pattern of the major fractures had not changed over the 10-year period, significant changes in the treatment pattern were observed. The closed-reduction and percutaneous pinning rates increased from 9.5 to 38.7% in fracture of the distal radius, 4.3 to 40% in the supracondylar humerus, and 1.8 to 22% in the forearm shaft. The changes in treatment pattern were also accompanied by a corresponding decrease in the open-reduction rate and hospital stay periods from <10% to 38% of patients being discharged within 1 day of admission in the 10-year period.

Osteopenia: A New Prognostic Factor of Curve Progression in Adolescent Idiopathic Scoliosis

BACKGROUND Studies have shown that 27% to 38% of girls with adolescent idiopathic scoliosis have systemic osteopenia. The aim of this study was to investigate whether osteopenia could serve as one of the important prognostic factors in predicting curve progression. METHODS A prospective study was performed in 324 adolescent girls with adolescent idiopathic scoliosis who had a mean age of thirteen and a half years. Bone mineral density of the spine and both hips was measured at the time of the clinical diagnosis of scoliosis. All patients were followed longitudinally until skeletal maturity or until the curve had progressed > or =6 degrees . The univariate chi-square test and stepwise logistic regression were used to predict the prevalence of curve progression, and a receiver operating characteristic curve was plotted. RESULTS The overall prevalence of curve progression was 50%. The prevalence of osteopenia at the spine and hips was 27.5% and 23.1%, respectively. A larger initial Cobb angle (odds ratio = 4.6), a lower Risser grade (odds ratio = 4.7), premenarchal status (odds ratio = 2.5), osteopenia in the femoral neck of the hip on the side of the concavity (odds ratio = 2.3), and a younger age at the time of diagnosis (odds ratio = 2.1) were identified as risk factors in predicting curve progression. A predictive model was established, and the area under the receiver operating characteristic curve of the model was 0.80 (p < 0.01). CONCLUSION Osteopenia may be an important risk factor in curve progression. The measurement of bone mineral density at the time of diagnosis may serve as an additional objective measurement in predicting curve progression in adolescent idiopathic scoliosis. The bone mineral density-inclusive predictive model may be used in treatment planning for patients with adolescent idiopathic scoliosis who are at high risk of curve progression.

Bone mineralization at the callotasis site after completion of lengthening

We studied the course of bone mineralization of regenerate bone after callotasis lengthening. Twenty-three patients (eight boys) (mean age at operation 11.5 years, range 4-17 years; leg length discrepancy [LLD] at surgery ranging from 4 to 13 cm) underwent dual-energy X-ray absorptiometry (DEXA) scanning weekly during the distraction phase, at 2 week intervals until removal of the fixator, and at the time of their out-patient visits thereafter, for a mean of 794 +/- 420 days after removal of the apparatus. At removal of the fixator, the bone mineral content (BMC) of the regenerate was nearly 70% of the normal contralateral limb. With time, this value gradually increased, and tended to reach normal values, with no significant difference between femur and tibia. With time, the BMC of the regenerate tends to return to the value of the normal contralateral limb. Probably, once the limb length discrepancy has been equalized, the mechanical stimuli imparted through weight-bearing to the lengthened limb are of the same magnitude bilaterally. In this instance, then, the newly formed bone, responding to these physical stimuli, would normalize its mineral content, confirming that bone remodeling continues well after lengthening is terminated. Mineralization of the regenerate after completion of the lengthening process reaches values significantly greater than at removal of the fixator, with an increase of >50% of the prelengthening values, regardless of the underlying pathology. The final value of this increased BMC is not significantly different than in the normal contralateral unoperated limb. At least part of the increase in bone mineralization following callotasis lengthening is due to the normal process of growth and development.

Abnormal functional responses of osteoblasts to leptin in adolescent idiopathic scoliosis

Objective Leptin has been postulated as one of the etiologic factors of AIS because of its important physiological functions in neuro-osseous development affecting skeletal growth, the onset of puberty, energy expenditure and body composition. Previous studies on the relationship between leptin and HR-pQCT derived bone quality parameters had found abnormal correlations in AIS girls, and suggested possible abnormalities in the leptin regulated bone metabolic pathways. Another study on AIS patients showed hyposensitivity to leptin in bone marrow derived mesenchymal stem cells This study aimed to investigate the effect of leptin on the functional responses of osteoblasts in AIS girls, and compare with that of controls.

Morphological and bone strength indices in girls with adolescent idiopathic scoliosis and their correlations with leptin and soluble leptin receptor

Results Compared with controls, AIS subjects had higher sOB-R level (p=0.006), higher SMI value (p=0.020) reflecting more rod-like structures within the trabecular compartment, and numerically lower stiffness (-2.03%) and estimated failure load (-3.07%). Significant negative correlation was found between SMI and serum total leptin level in AIS (r=-0.325; p=0.003) but not in controls (p=0.533). Significant positive correlations were found between stiffness, estimated failure load, and serum total leptin in both AIS (r=0.278, p=0.003; r=0.268, p=0.004 respectively) and controls (r=0.462, p<0.001; r=0.468, p<0.001 respectively). Conclusion

Recurrent destabilising paediatric pelvic arterial haemorrhage: Choosing the embolisation technique that works – A case report

A 12-year-old male child presented with a history of fall from three floors height with a stable pelvic fracture but destabilised haemodynamically soon after from pelvic arterial haemorrhage. Two attempts of selective embolisation controlled the haemorrhage transiently but recurrent pelvic arterial haemorrhage ensued jeopardising patient’s haemodynamic status. Pelvic arterial haemorrhage was ultimately controlled by a unilateral non-selective embolisation of anterior and posterior divisions of internal iliac artery without any immediate or long-term ischaemic complications. Unilateral non-selective transcatheter arterial embolisation in paediatric pelvic arterial haemorrhage may be used as a viable management option with the potential of evading ischaemic complications and effective in selective embolisation failures.

Effect of upright posture on tonsillar level in adolescent idiopathic scoliosis

Results In AIS patients, the cerebellar tonsil position was significantly lower in the upright than the supine position (-0.7 +/-1.5 vs +1.2+/-1.7, p<0.00001) while in normal subjects, there was no change in cerebellar tonsil position between upright and supine positions (mean +2.1+/-1.7 vs +2.2 +/-1.8, p = 0.93). AIS patients also had a greater degree of tonsillar excursion between upright and supine positions compared to normal subjects (mean -1.9 +/-1.6 vs -0.1 +/-1.7, p<0.00001). More AIS patients tended to have tonsillar descent in the upright position rather than the supine position though this did not reach statistical significance (28% in supine position vs 48% in standing position, p=0.15). There is slightly better correlation between tonsillar level and Cobb angle in upright position (r = 0.45, p = 0.01) than those in supine position (r= 0.31, p=0.03) in AIS patients. Conclusion AIS patients have more tonsillar descent in the upright position and a greater degree of tonsillar excursion between supine and upright positions compared to matched control subjects. Apart from supporting the hypothesis of relative cord tethering in AIS, the results also enhance the likelihood of more significant chronic dynamic compression of the brainstem and upper cervical cord in AIS. Whether this will lead to chronic insult with subclinical neurophysiological disturbance, affecting both dynamic postural balance and SSEP, and contributing to the etiopathogenesis of AIS, warrants further study.

ACVR1 mutation and Fibrodysplasia Ossificans Progressiva in Chinese children

Fibrodysplasia Ossificans Progressiva (FOP) is a rare autosomal dominant connective tissue disorder characterized by congenital great toes malformation and progressive heterotopic osteogenesis leading to progressive debilitating ankylosis of the body. A recurrent missense mutation in the activin receptor 1A/activin-like kinase 2 (ACVR1/ALK2), a bone morphogenetic protein (BMP) receptor, was identified in almost all FOP patients1. Here we report two unrelated Chinese FOP adolescents harbouring this mutation. Both were referred to the rheumatological service with joint stiffness and abnormal calcification on imaging.