Paediatric lower limb deformity correction with the Eight Plate: adverse events and correction outcomes of 126 patients from an international multicentre study.

No large multicentre studies have yet been published on tension-band-like implants such as the Eight Plate to treat limb-length discrepancies and varus valgus deformities in children. Therefore, we carried out a retrospective international multicentre study including 126 patients to assess outcomes and to reliably quantify the incidence of implant-related and growth-plate related adverse events (AEs). Correction was achieved in 66% of varus valgus deformities and in 59% of limb-length discrepancies and maintained in 85%. Twenty (18%) patients experienced 43 AEs, which were primarily screw-related. The AE rate of the Eight Plate is low; however, many of them could be avoided through tighter monitoring.

Nonunion of forearm shaft fractures in children after intramedullary nailing.

The elastic stable intramedullary nailing (ESIN) is the current treatment of choice for unstable forearm shaft fractures in children. There is no large study on paediatric nonunion of forearm shaft fractures in children after intramedullary nailing. There are only sporadic reports on nonunions after ESIN in children. The aim of this study was to define predisposing factors of nonunions in paediatric forearm fractures. All children who had been treated for forearm fractures by ESIN in our hospital from 1990 to 2006, and all children treated elsewhere surgically and being followed up at our institution were included in the study. In these children, we identified all patients who did not show bony consolidation of the fracture after 6 months from ESIN. Over a period of 16 years, 537 patients were primarily treated in our hospital and 55 children had been initially treated in a different institution. Six children were identified to fulfill the criteria of having developed a pseudarthrosis. Of these six children, three patients had been primarily treated in another hospital and three were our original patients. The average age was 11.1 years (9-14 years). There were only pseudarthroses of the ulna to be observed. In five children, the pseudarthrosis was in the middle third and in one patient in the distal third of the ulna. There were five closed fractures and one first-degree open fracture. Five times an open reduction of the ulna had been performed because closed reduction and insertion of the ESIN was impossible, whereas the radius had been treated closed in five cases and open in one case for intramedullary stabilization. Three cases were refractures, in one child it was a second refracture. In one case, we identified a technical error as cause of the development of the pseudarthrosis. Four children needed a revision surgery. In these children, the ulna was plated. Two patients showed spontaneous healing of the pseudarthrosis. In five patients, there was a hypertrophic pseudarthrosis present and in one case was hypotrophic pseudarthrosis. The reintervention was necessary because of increasing deformity in four patients and implant failure in one case. In conclusion, Non-unions after forearm fractures are observed in children and adolescents mainly in the middle third of the ulna. With the need of initial open reduction or the presence of an open fracture in the first instance, the risk of developing a pseudarthrosis. It may also be higher in such cases, which represent a refracture. Despite the small risk of developing a pseudarthrosis after forearm fracture, the indication for ESIN is clear. The surgical trauma needs to be as minimal as possible in cases with open reduction with as little as possible compromise of the blood circulation of the affected bone.

Human short-wavelength-sensitive cone light adaptation.

The cone-driven visual system is able to regulate its sensitivity effectively from twilight to bright sunlight. On the basis of a novel combination of short-wavelength-sensitive (S-) cone measurements of temporal sensitivity and temporal delay, we show that S-cone light adaptation is achieved not only by trading unwanted sensitivity for speed but also by an additional process that counterintuitively increases the overall sensitivity as the light level rises. Our results are consistent with comparable middle-wavelength-sensitive (M-) cone measurements made in protanopic observers and can be accounted for by the same two-parameter model developed to account for the M-cone data (A. Stockman, M. Langendörfer, H. E. Smithson, & L. T. Sharpe, 2006). Each stage of the model can be linked to molecular mechanisms occurring within the photoreceptor: the speeding up to increases in the rates of decay of active and messenger molecules, the unexpected sensitivity increases to increased rates of molecular resynthesis and changes in channel sensitivity, and the sensitivity decreases to bleaching. Together, these mechanisms act to maintain vision in an optimal operating range and to protect it from overload.

Human cone light adaptation: from behavioral measurements to molecular mechanisms.

The ability of the cone visual system to regulate its sensitivity from twilight to bright sunlight is an extraordinary feat of biology. Here, we investigate the changes in visual processing that accompany cone light adaptation over a 5 log10 unit intensity range by combining measures of temporal sensitivity made in one eye with measures of the temporal delay between the two eyes in different states of adaptation. This combination of techniques, which provides more complete information than has been available before, leads to a simple model of steady-state light adaptation. At high light levels, visual sensitivity is maintained mainly by photopigment bleaching. At low-to-moderate light levels, it is maintained by trading unwanted sensitivity for speed and by an additional process that paradoxically increases the overall sensitivity as the light level rises. Each stage of the model can be linked to molecular mechanisms within the photoreceptor: The speeding up can be linked to faster rates of decay of activated molecules; the paradoxical sensitivity increases can be linked to faster rates of molecular resynthesis and to changes in channel sensitivity; and the sensitivity decreases can be linked to bleaching. Together, these mechanisms act to maintain the cone visual system in an optimal operating range and to protect it from overload.