Central core myopathy with RYR1 mutation masks 5q spinal muscular atrophy.

We report the case of a male who presented in infancy with motor delay and muscle weakness. Typical muscle biopsy features and heterozygous RYR1 mutation confirmed a diagnosis of central core disease. Family studies showed this to be a de-novo mutation. Some years later, his two older teenage brothers presented with proximal muscle weakness. Neurophysiology, muscle biopsy and DNA studies confirmed spinal muscular atrophy. Subsequent genetic studies in the index case also confirmed homozygous deletions of exon 7 and 8 in the SMN gene. Review of the original muscle biopsy showed classical features of central core disease with no evidence to suggest denervation, such that the diagnosis of spinal muscular atrophy could not have been suspected in the absence of the family history.

Elevated, straight-arm traction for supracondylar fractures of the humerus in children.

Between January 1995 and December 2000, 112 children with a closed displaced supracondylar fracture of the humerus without vascular deficit, were managed by elevated, straight-arm traction for a mean of 22 days. The final outcome was assessed using clinical (flexion-extension arc, carrying angle and residual rotational deformity) and radiographic (metaphyseal-diaphyseal angle and humerocapitellar angle) criteria. Excellent results were achieved in 71 (63%) patients, 33 (29%) had good results, 5 (4.4%) fair, and 3 (2.6%) poor. All patients with fair or poor outcomes were older than ten years of age. Elevated, straight-arm traction is safe and effective in children younger than ten years. It can be effectively used in an environment that can provide ordinary paediatric medical care and general orthopaedic expertise. The outcomes compare with supracondylar fractures treated surgically in specialist centres.

The spectrum of pathology in central core disease.

Central core disease is a congenital myopathy with muscle weakness defined pathologically by the presence of extensive areas in muscle fibres that are devoid of oxidative enzyme activity. The gene responsible has been shown to be the ryanodine receptor 1 on chromosome 19q13 and mutations have now been identified in several patients. Some cases with the morphological defect remain molecularly undefined, particularly those studied before molecular studies were available. We have studied three families with congenital onset, each with a dominantly inherited mutation in a C-terminal exon of the ryanodine receptor 1. They illustrate the spectrum of pathology that can be observed in patients with the myopathic features of central core disease. We show that extensive fibrosis and fat may be present, type 1 fibre uniformity may occur in the absence of cores; cores may be central or peripheral, single or multiple; and that an appearance of multiple focal minicores might cause a diagnostic pathological dilemma. In addition, we show the value of immunocytochemistry in identifying cores, in particular the use of antibodies to desmin and gamma-filamin.

Fracture stiffness in callotasis determined by dual-energy X-ray absorptiometry scanning.

Assessing healing after distraction limb lengthening is essential to manage patients undergoing callotasis for leg lengthening or bone transport. Direct measurement of fracture stiffness can assess healing but the equipment may not be available. In addition, it requires removal of the fixator, which may be complicated for ring fixators. The present study investigates whether an equivalent measure of healing can be based on the mineral density pattern from dual-energy X-ray absorptiometry (DXA) scans. Nine consecutive patients undergoing callotasis were studied. Bending stiffness of the distraction segment was measured and DXA scans were performed regularly starting 6 weeks after completing distraction. In all, 23 simultaneous readings of bending stiffness and DXA scans were obtained. All density patterns showed a distinct minimum value of bone mineral density. We found a high and significant correlation between fracture bending stiffness and the square of the total mineral content at the location of minimum bone density (r2 = 0.77, P < 0.001). We conclude that DXA scans can be used reliably and effectively to determine fracture bending stiffness, valuable for determining both time of frame removal and delay in union.

Stiffness measurements to assess healing during leg lengthening. A preliminary report.

We describe a technique for measuring the stiffness of regenerate bone after leg lengthening. This allows early identification of slow healing by reference to normal patterns. We determined the time of removal of the fixator from clinical and radiological information independent of the stiffness result. In a series of 30 leg lengthenings there were no refractures when the tibial stiffness had reached 15 Nm/degree or the femoral stiffness 20 Nm/degree. Three refractures occurred at lower stiffness values. The technique is simple to perform, will allow a reduction in plain radiography and is recommended for routine postoperative management.