We have had experience of an 18-month-old boy with a cardiomyopathy who died a few minutes after removal of his cast with a saw, apparently from a malignant cardiac arrhythmia triggered by anxiety. We therefore examined the anxiety reaction to this method of removal of a plaster cast in 20 healthy children; ten were provided with hearing protectors and ten were not. The level of anxiety was assessed by measuring the heart rate, a known physiological indicator of anxiety, before, during and five minutes after removal of the cast. The noise level was also measured. The results showed a mean increase in heart rate during the procedure of 27.9 beats per minute (bpm) (26.9%) in the children with no hearing protectors and 10.4 bpm (11.1%) in children who used hearing protectors (p < 0.001). Five minutes after the procedure the heart rate had returned to the baseline rate in all patients.

We recommend that hearing protectors should be used in children undergoing removal of a plaster cast to decrease the anxiety reaction. If possible, clinicians should avoid the use of a saw for this purpose in children with a cardiomyopathy.

Nuclear magnetic resonance imaging (MRI) was used to study the normal knee. As well as revealing bone quality, MRI provided useful information on intra-articular and extra-articular soft tissues. Midsagittal views gave clear images of the cruciate ligaments, and of the patellar and quadriceps tendons. Parasagittal views were the best for delineating the menisci which, like ligaments and tendons, are of low intensity; the semimembranosus tendon and its insertion to the proximal tibia were also seen clearly in these views. The cruciate ligaments and menisci, though visible in the coronal view also, were better seen in the sagittal view. Axial views provided information on the structure of the patella, its cartilage, the patellofemoral joint and posterior soft-tissue structures.