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Objective: Measurement of ventricular size is important in pediatric patients with hydrocephalus, especially those who are being followed with cerebrospinal fluid (CSF) shunts. While volumetric techniques are a more accurate estimate of true ventricular volume, they are often impracticable when multiple modalities including ultrasound are used. Volumetric area and linear measurements were compared to find the most reasonable measurement method. Methods: Sixty-four computed tomography (CT), magnetic reasonance imaging (MRI), and ultrasound (US) scans from 25 children aged 0–17 years with hydrocephalus, before and after treatment, were measured. Measurements included ventricular volume, a ventricular/brain ratio, and four standard linear measures (Evans’ ratio, Huckman’s measurement, minimal lateral ventricular width, and lateral ventricular span at the body). We also included a new ratio, which accounts for often disproportionate occipital horn expansion in pediatric patients, called the frontal and occipital horn ratio. Volume and linear measurements were compared using the Spearman’s correlation coefficients and correlations were further differentiated using a Z test statistic. The frontal and occipital horn ratio was also measured on CT, MRI, and US scans from 44 normal children aged 0–17 years to identify normal values. The effect of age was determined by linear regression. Results: The best linear correlation with ventricular size was the frontal + occipital horn ratio (r = 0.852) and was equivalent to the ventricular/brain ratio (r = 0.891), previously shown to have the highest correlation with ventricular volume. Evans’ ratio correlates less well (r = 0.423). The normal frontal and occipital horn ratio is 0.37 and is independent of age. Conclusions: The frontal and occipital horn ratio is a simple method of evaluating ventricular size in pediatric hydrocephalus patients with CSF shunts.

etal-on-metal (MOM) bearings for hip arthroplasty are increasing in popularity. Concern remains, however, regarding the potential toxicological effects of the metal ions which these bearings release.The serum levels of cobalt and chromium in 22 patients who had undergone MOM resurfacing arthroplasty were compared with a matched group of 22 patients who had undergone 28 mm MOM total hip arthroplasty (THA).At a median of 16 months (7 to 56) after resurfacing arthroplasty, we found the median serum levels of cobalt and chromium to be 38 nmol/l (14 to 44) and 53 nmol/l (23 to 165) respectively. These were significantly greater than the levels after 28 mm MOM THA which were 22 nmol/l (15 to 87, p = 0.021) and 19 nmol/l (2 to 58, p < 0.001) respectively.Since the upper limit for normal patients without implants is typically 5 nmol/l, both groups had significantly raised levels of metal ions. MOM bearings of large diameter, however, result in a greater systemic exposure of cobalt and chromium ions than bearings of small diameter. This may be of relevance for potential long-term side-effects. It is not known to what extent this difference is due to corrosion of the surfaces of the component or of the wear particles produced. MMetal-on-metal (MOM) bearings were first used in total hip arthroplasty (THA) over 40 years ago.1-3 Because of a limited understanding of the engineering of these bearings and early failures in some cases, they lost popularity to the lowfriction stainless-steel/ultra-high-molecular-weight polyethylene bearing developed by Charnley. 4 Over the past 15 years, with an improved understanding of the aetiology of aseptic loosening and of the science of wear, there has been increased interest in the use of MOM bearings. 5,6 Of the many engineering factors which have contributed to the success of the MOM bearing, the metallurgy, diametric bearing clearance, sphericity and surface finish are thought to be most important. 7-9All metal implants, especially those which include MOM bearings corrode at a rate determined, in part, by their surface area. 10 Further, side-effects relate directly to the particles of metal which are produced and their subsequent fate within the body. Our hypothesis was that the production of wear debris, and thus metal ion release, would be less after resurfacing arthroplasty than after THA using a 28 mm MOM bearing. This was based on the theoretical fluid film lubrication and reduced potential for the production of wear debris which is thought to occur in MOM bearings of large diameter, despite the increased surface area available for corrosion with these implants. 11 Patients and MethodsEvaluation of patients. All joint arthroplasties are prospectively registered on a computerised database. We contacted patients who had undergone either unilateral MOM or resurfacing arthroplasty at least six months earlier and asked them to attend dedicated clinics. They completed a questionnaire and provided a sample of blood for analysis of cobalt and chromium. Since we were interested in estima...

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Decline of ventricular size over time is not affected by these different shunt valve designs. This suggests that the mechanical models of hydrocephalus on which the designs were based are inadequate. Ventricular catheter tip location and ventricular catheter environment are important. Techniques to accurately place ventricular catheters and new valve designs that effectively control ventricular size might reduce shunt malfunction.

The histopathological appearances of the tendon sheath and synovium from 23 patients treated surgically for de Quervain's disease are described and compared with 24 controls. The condition was not characterized by inflammation, but by thickening of the tendon sheath and most notably by the accumulation of mucopolysaccharide, an indicator of myxoid degeneration. These changes are pathognomonic of the condition and are not seen in control tendon sheaths. The term 'stenosing tenovaginitis' is a misnomer and we believe that de Quervain's disease is a result of intrinsic, degenerative mechanisms rather than extrinsic, inflammatory ones.

Phase pure hydroxyapatite (HA) and two silicate-substituted hydroxyapatites (0.8 and 1.5 wt% Si, or 2.6 and 4.9 wt% SiO4) were prepared by aqueous precipitation methods. The filter-cakes of HA and silicate-substituted hydroxyapatite (SiHA) compositions were processed into granules 1.0-2.0 mm in diameter and sintered at 1200 degrees C for 2 h. The sintered granules underwent full structural characterisation, prior to assessment in an ovine defect model by implantation for a period of 6 and 12 weeks. The results indicate that HA and SiHA implants were well accepted by the host tissue, with no evidence of inflammation. New bone formation was observed directly on the surfaces and in the spaces between the granular implants. Quantitative histomorphometry as determined by the percentage of bone ingrowth and bone coverage for both SiHA implant compositions was significantly greater than that for phase pure HA. These findings indicate that the in vivo bioactivity of hydroxyapatite was significantly improved by the incorporation of silicate ions into the HA structure, making SiHA ceramics attractive alternatives to conventional HA materials for use as bone graft substitute ceramics.

We have investigated whether the thigh tourniquet used during total knee replacement (TKR) influenced the development of postoperative wound hypoxia and was a cause of delayed wound healing.We allocated randomly 31 patients (31 TKRs) to one of three groups: 1) no tourniquet; 2) tourniquet inflated at low pressure (about 225 mmHg); and 3) tourniquet inflated to high pressure of about 350 mmHg. Wound oxygenation was measured using transcutaneous oxygen electrodes.In the first week after surgery, patients with a tourniquet inflated to a high pressure had greater wound hypoxia than those with a low pressure. Those without a tourniquet also had wound hypoxia, but the degree and duration were less pronounced than in either of the groups with a tourniquet.Use of a tourniquet during TKR can increase postoperative wound hypoxia, especially when inflated to high pressures. Our findings may be relevant to wound healing and the development of wound infection. J Bone Joint Surg [Br] 2001;83-B:40-4.