Impaired bone health and asymptomatic vertebral compressions in fracture-prone children: a case-control study

Frequent fractures in children may be a sign of impaired bone health, but it remains unestablished when and how fracture‐prone children should be assessed. This prospective study elucidated skeletal characteristics and predisposing factors in children with recurrent fractures. Findings were used to establish guidelines for screening. During a 12‐month period we recorded fracture history for all children (n = 1412) treated for an acute fracture at a large university hospital. All apparently healthy children over 4 years of age, who had sustained: (1) at least one vertebral fracture; (2) two long‐bone fractures before age 10 years; or (3) three long‐bone fractures before age 16 years, were recruited. They underwent dual‐energy X‐ray absorptiometry (DXA), laboratory tests, and spinal radiography. Information regarding family history and lifestyle factors were collected. Findings were compared with healthy controls. Sixty‐six fracture‐prone children (44 males, mean age 10.7 years; 5% of all children with fractures) were identified. Altogether, they had sustained 183 long‐bone fractures (median 3, range 0–7); 11 children had sustained vertebral fracture(s). Patients had significantly lower bone mineral density (BMD) at lumbar spine (p < 0.001), hip (p = 0.007), and whole body (p < 0.001) than the controls; only 5 children (8%) had a BMD Z‐score < ?2.0. Asymptomatic vertebral compressions were prevalent, especially in those under 10 years of age. Hypercalciuria (11%) and hyperphosphaturia (22%) were significantly more prevalent than in controls. Serum concentration of 25‐hydroxyvitamin D (S‐25OHD) was below 50 nmol/L in 55%; low levels were associated with low BMD and vertebral compressions. The fracture‐prone children had lower calcium intake, less physical activity, and more often had siblings with fractures than the controls. The findings suggest that a thorough pediatric evaluation, including DXA and spinal radiography, is often indicated already after a second significant low‐energy fracture in children, in order to detect potentially preventable adverse lifestyle factors and nutritional deficits and to identify those with compromised overall bone health. © 2012 American Society for Bone and Mineral Research.     

Recurrent torsades de pointes after catheter ablation of incessant ventricular bigeminy in combination with QT prolongation

A 45-year-old woman, who had received a single-chamber implantable cardioverter defibrillator (ICD) due to ventricular fibrillation 5 years ago, was admitted for catheter ablation of incessant right ventricular outflow tract bigeminy. After successful ablation recurrent torsades de pointes associated with a prolonged corrected QT (QTc) interval were initiated by polymorphic premature ventricular complexes. Genetic testing revealed a heterozygous missense mutation in the SCN5A-gene (p.Arg190Gln, Exon 5), consistent with long QT-syndrome 3. DDDR pacing following implantation of an atrial lead prevented further ventricular tachyarrhythmias.     

Quadriceps femoris muscle function prior and after total knee arthroplasty in women with knee osteoarthritis

Purpose

The aim of the present study was to evaluate an isometric voluntary force generation and relaxation capacity of the quadriceps femoris (QF) muscle prior and after total knee arthroplasty (TKA).

Methods

Isometric maximal voluntary contraction force, rate of force development, voluntary activation, half-relaxation time, and latency of contraction of the QF muscle were recorded in 12 female patients (aged 49–68 years) with knee osteoarthritis one day before, 3 and 6?months following TKA in the operated and nonoperated leg. Knee pain intensity was assessed by visual analog scale, and Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire was used to assess knee problems during daily living.

Results

A significant decrease in knee pain and significant increase in KOOS were established after TKA. Maximal voluntary isometric force in the operated leg was lower (P?P?Conclusions The present study indicated reduced maximal and explosive strength of quadriceps femoris muscle in the operated leg 3 and 6?months after TKA with no significant changes in voluntary activation, and capacity for rapid contraction and relaxation.

Level of evidence

Prospective comparative study, Level II.