Comparing Mersilene* tape and stainless steel wire as sublaminar spinal fixation in the Chagma baboon (Papio ursinus).

The development of segmental instrumentation has been a major advancement in the treatment of spinal problems, but the use of sublaminar stainless steel wire (SSW) has not been without untoward effects. This study reports a comparison of Mersilene* tape (MT) and stainless steel wire (SSW) used for sublaminar fixation in the Chagma baboon (Papio Ursinus). A similar comparative study has not been reported, although the local effects of sublaminar SSW in the spinal canal have previously been described. The adult Chagma baboon was selected as the experimental animal due to its partial upright posture and spinal anatomy, similar to that of the human. Six levels of the thoracolumbar spine were instrumented with custom designed Harrington hooks and regular one-quarter inch threaded rods used as a distraction system. The four intervening laminae were fixed to the rods using doubled-over, eighteen gauge sublaminar SSW in six cases and five millimeter MT in six cases. Computed axial tomography used to measure the AP diameter of the bony spinal canal revealed the AP space occupied by the SSW and MT to be 32 percent and 14.8 percent respectively. In the MT group, the overlying dura mater was found to be totally intact and revealed no signs of abnormal tissue response. A well-formed connective tissue membrane consisting of dense connective tissue surrounded the MT and was found to consist of more mature fibers than that found in the SSW group. The dura-implant interface was examined histologically and a distinct membrane was identified between the dura and the superficial aspect of the MT's, as well as intervening between the two MT's. Following removal of the MT, in contrast to the SSW, it was apparent that the underlying dura was not injured, most probably due to the soft consistency of the Mersilene* tape and the well-formed overlying membrane. On clinical grounds the fixation in both groups was adequate but the MT group formed a well-circumscribed membrane that made removal of the MT easier and potentially safer. The AP space occupied by the spinal implant was also found to be less with MT as opposed to SSW.

[Chronic osteomyelitis - a diagnostic dilemma]. / Chroniese osteomiëlitis--'n diagnostiese dilemma.

Infective skeletal lesions can mimic bony tumours. Bony lesions without periosteal reactions in adult patients with normal leucocyte counts will have a different differential diagnosis from that of children with bony lesions and a periosteal reaction. In the latter, osteomyelitis should be distinguished from Ewing's sarcoma and osteogenic sarcoma. Due to the difficult preoperative diagnosis a retrospective study was undertaken which included 14 patients with the histological diagnosis of chronic osteomyelitis but normal leucocyte count and no periosteal reaction. Radiographs showed cavities in 82%, infiltration in 12% and sclerosis in 6% of cases. All patients who underwent skeletal scintigraphy studies showed increased uptake in the lesions. Magnetic resonance showed increased signal intensity in T2 images. Ordinary radiographs are still the most valuable primary investigation for skeletal lesions.

Effects of caffeine ingestion on thermoregulatory and myocardial function during endurance performance.

The effect of caffeine administration on thermoregulatory and myocardial function during endurance performance was studied. A caffeine solution (250 ml; 5 mg caffeine/kg body weight) ingested 1 hour prior to 2 hours of running by 5 subjects was shown to have no significant effect on sweat loss, water deficit, percentage change in plasma volume, final rectal temperature and serum electrolyte levels, as compared with a similar control group who were given a caffeine-free drink. The rectal temperatures in both groups did, however, reach levels known to be associated with heatstroke despite a recommended regimen of fluid replacement. No pathological electrocardiographic changes occurred in either group. It is therefore concluded that the use of caffeine for ergogenic purposes by young athletes is a relatively safe procedure.