Factors associated with the participation of children with complex communication needs.

The aim of this study was to conduct a preliminary analysis of relations between child and environmental variables, including factors related to communication aid provision, and participation in informal everyday activities in a sample of children with complex communication needs. Ninety-seven caregivers of children provided with communication aids responded to a questionnaire survey. Child variables assessed were level of ability, trait emotional self-efficacy, and competence in communication aid use. Environmental variables assessed were the impact of childhood disability on the family, family socio-economic category, perceived reliability of electronic communication aids provided to children, and ease of use of the aid. The outcome measure was the intensity of child participation in informal activities. Significant correlations were observed between participation scores and the following variables: child age, level of ability, trait emotional self-efficacy, and family impact of childhood disability. Regression analyses highlighted trait emotional self-efficacy and, to a lesser degree, family impact of childhood disability as the strongest potential predictors of participation. While aspects of child personality may be difficult to disentangle from behaviours related to disability type or developmental age, this research highlights a clinical requirement to assess systematically child behaviours relating to their general emotional functioning.

Vacuum-mixing cement does not decrease overall porosity in cemented femoral stems: an in vitro laboratory investigation.

The role of vacuum mixing on the reduction of porosity and on the clinical performance of cemented total hip replacements remains uncertain. We have used paired femoral constructs prepared with either hand-mixed or vacuum-mixed cement in a cadaver model which simulated intra-operative conditions during cementing of the femoral component. After the cement had cured, the distribution of its porosity was determined, as was the strength of the cement-stem and cement-bone interfaces. The overall fraction of the pore area was similar for both hand-mixed and vacuum-mixed cement (hand 6%; vacuum 5.7%; paired t-test, p = 0.187). The linear pore fractions at the interfaces were also similar for the two techniques. The pore number-density was much higher for the hand-mixed cement (paired t-test, p = 0.0013). The strength of the cement-stem interface was greater with the hand-mixed cement (paired t-test, p = 0.0005), while the strength of the cement-bone interface was not affected by the conditions of mixing (paired t-test, p = 0.275). The reduction in porosity with vacuum mixing did not affect the porosity of the mantle, but the distribution of the porosity can be affected by the technique of mixing used.

The provision of communication aids to children in England: an analysis of applications to the Communication Aids Project.

BACKGROUND: Children who experience difficulties in face-to-face interaction, understanding language and developing literacy can benefit from the provision of communication aids such as speech synthesizers and specialist software applications that support their social participation and learning. The Communication Aids Project (CAP) was a national initiative by the Department for Education and Skills in England, aimed at supporting and developing the provision of communication aids to children. This paper presents an analysis of the number and type of applications to CAP. In so doing, the paper begins to explore how the need for communication aids might be understood in England. METHODS: The analysis was carried out on a database of 3060 anonymized records, representing applications to CAP between January 2002 and January 2004. RESULTS: Applications to CAP were made on behalf of children with a broader range of disabilities than might be assumed, including a relatively high proportion of children with autistic spectrum disorder. Rates of application to CAP varied in line with Local Education Authority population size [e.g. total pupils, total pupils with special educational needs (SEN)], rather than indicators of regional variation in SEN provision (e.g. proportion of population identified as having SEN). CONCLUSIONS: Within a context of changing services to children in England and increasing emphasis on the plurality and contestability of services, the relevance of these findings for service providers and service commissioners is discussed.

In vivo assessment of hydroxyapatite and silicate-substituted hydroxyapatite granules using an ovine defect model.

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.

The proximal extent of the ankle capsule and safety for the insertion of percutaneous fine wires.

We have assessed the proximal capsular extension of the ankle joint in 18 patients who had a contrast-enhanced MRI ankle arthrogram in order to delineate the capsular attachments. We noted consistent proximal capsular extensions anterior to the distal tibia and in the tibiofibular recess. The mean capsular extension anterior to the distal tibia was 9.6 mm (4.9 to 27.0) proximal to the anteroinferior tibial margin and 3.8 mm (-2.1 to 9.3) proximal to the dome of the tibial plafond. In the tibiofibular recess, the mean capsular extension was 19.2 mm (12.7 to 38.0) proximal to the anteroinferior tibial margin and 13.4 mm (5.8 to 20.5) proximal to the dome of the tibial plafond. These areas of proximal capsular extensions run the risk of being traversed during the insertion of finewires for the treatment of fractures of the distal tibia. Surgeons using these techniques should be aware of this anatomy in order to minimise the risk of septic arthritis.

Levels of metal ions after small- and large-diameter metal-on-metal hip arthroplasty.

Metal-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.

Dislocation after total hip replacement in relation to metal-on-metal bearing surfaces.

Metal-on-metal (MOM) is a commonly used bearing notable for its 'suction fit' when lubricated. In this study, we examined the capacity for MOM bearings to protect against dislocation after total hip replacement (THR). We undertook a clinical investigation to compare the rate of dislocation of MOM bearings with those of ceramic-on-polyethylene (COP) bearings and found that one MOM bearing dislocated in a series of 109 hips (0.9%) compared with nine of 145 hips (6.2%) in the COP group (p = 0.02). We also performed an in vitro investigation comparing the peak forces generated during forced separation of the two bearings of the same dimensions at velocities from 1 to 50 cm/s. This revealed that the MOM bearing generated significant resistance to separation at all velocities (maximum mean 24 N), whereas the COP did not (maximum mean 1.9 N, p < 0.001). We conclude that MOM bearings are more stable to dislocation than COP bearings as a result of the interfacial forces provided by a thin, lubricating fluid.

Increased cancellous bone in the femoral neck of patients with coxarthrosis (hip osteoarthritis): a positive remodeling imbalance favoring bone formation.

Osteoporosis is caused by an imbalance between bone resorption and formation which results in an absolute reduction in bone mass. In a previous study we highlighted a condition, osteoarthritis of the hip (coxarthrosis, cOA), where an imbalance between resorption and formation provided beneficial effects in the form of an absolute increase in bone mass. We demonstrated that the femoral neck in patients with cOA had increased cancellous bone area, connectivity and trabecular thickness which might contribute to the protection against fracture associated with the condition. The aim of the present study was to analyze forming and resorbing surfaces in coxarthritic cancellous bone to assess whether increased formation or reduced resorption could be responsible for these structural changes. Whole cross-sectional femoral neck biopsies were obtained from 11 patients with cOA and histomorphometric parameters compared with 14 age- and sex-matched cadaveric controls. The ratio of osteoid surface to bone surface was 121% ( p<0.001) higher in the cases but there was no significant difference in resorptive surface. The percentage osteoid volume to bone volume (%OV/BV; +270%, p<0.001) and osteoid width (O.Wi; +127%, p<0.001) were also higher in the cases. This study suggests that the increased cancellous bone mass seen in cases of cOA is due to increased bone formation rather than decreased bone resorption. Investigation of the cellular and biochemical basis for these changes might provide new insights into the pathogenesis of osteoarthritis and highlight novel biological mechanisms regulating bone multicellular unit (BMU) balance that could be relevant to developing new interventions against hip and other osteoporotic fractures.

Increased femoral neck cancellous bone and connectivity in coxarthrosis (hip osteoarthritis).

Patients with coxarthrosis (cOA) have a reduced incidence of intracapsular femoral neck fracture, suggesting that cOA offers protection. The distribution of bone in the femoral neck was compared in cases of coxarthrosis and postmortem controls to assess the possibility that disease-associated changes might contribute to reduced fragility. Whole cross-section femoral neck biopsies were obtained from 17 patients with cOA and 22 age- and sex-matched cadaveric controls. Densitometry was performed using peripheral quantitated computed tomography (pQCT) and histomorphometry on 10-microm plastic-embedded sections. Cortical bone mass was not different between cases and controls (P > 0.23), but cancellous bone mass was increased by 75% in cOA (P = 0.014) and histomorphometric cancellous bone area by 71% (P < 0.0001). This was principally the result of an increase of apparent density (mass/vol) of cancellous bone (+45%, P = 0.001). Whereas cortical porosity was increased in the cases (P < 0.0001), trabecular width was also increased overall in the cases by 52% (P < 0.001), as was cancellous connectivity measured by strut analysis (P < 0.01). Where osteophytic bone was present (n = 9) there was a positive relationship between the amount of osteophyte and the percentage of cancellous area (P < 0.05). Since cancellous bone buttresses and stiffens the cortex so reducing the risk of buckling, the increased cancellous bone mass and connectivity seen in cases of cOA probably explain, at least in part, the ability of patients with cOA to resist intracapsular fracture of the femoral neck during a fall.

Hip arthroscopy: complications in 1054 cases.

Although arthroscopic surgery of the hip is becoming a more frequently done operation, there is relatively few data in the literature regarding the frequency of complications. In the current prospective study of 1054 consecutive hip arthroscopies, the authors report an overall complication rate of 1.4%. Complications included neurapraxia, portal wound bleeding, portal hematoma, trochanteric bursitis, and instrument breakage. The only major complication was one case of septic arthritis. It is concluded that, done properly, hip arthroscopy can be a considered a low-risk procedure.

The ratio of osteocytic incorporation to bone matrix formation in femoral neck cancellous bone: an enhanced osteoblast work rate in the vicinity of hip osteoarthritis.

Recently it has been shown that an inactivating mutation in the TGFb-SMAD3 signaling pathway, which increases the conversion of osteoblasts to osteocytes, is accompanied by bone loss combined with increased osteocyte density. We hypothesized that increased matrix TGFb, known to occur in osteoarthritis, might cause the reverse of these effects in man. Because coxarthrosis (cOA) is associated with a reduced risk of femoral neck fracture, whole cross-section femoral neck biopsies were obtained from 11 patients with femoral neck fracture, 14 patients with cOA, and 22 age-and sex-matched controls. Lacunar density (Lc x mm2), osteocyte density (Ot x mm2), and cancellous wall width (Cn x W x Wi), were compared between cases of coxarthrosis, femoral neck fracture (FNF) and controls. In cOA, Lc.mm2 was reduced by 24% (P <0.001) while in FNF it was increased by 20% (P <0.001). Cn x W x Wi was increased in cOA by 22% (P <0.05) and in FNF was reduced by 27% (P <0.001). Lc x mm2 was inversely related to percentage cancellous bone area (adj. r2 = 0.373; P <0.01) and wall widths, r2 = 0.382, P <0.001. The reduction in osteocyte lacunar density coupled with increased wall width is consistent with a model of cOA effects on bone in which increased levels of matrix TGFb might prolong the effective lifespan or work rate of the osteoblast and delay its incorporation into the matrix as an osteocyte. One possible approach to strengthening bone in osteoporosis might be to enhance the effective lifespan of the osteoblast by modulating TGFb-related pathway activity in its local environment.

A simple guide to determine the magnification of radiographs and to improve the accuracy of preoperative templating.

Templates are used in the preoperative planning of many orthopaedic procedures. The magnification of the bones on preoperative radiographs can vary despite using standardised radiological techniques. Templates will give misleading measurements unless this magnification is quantified. A coin may be used to calculate the magnification, with significant improvement in the accuracy of templating (p = 0.05). A group of patients undergoing uncemented arthroplasty of the hip was at high risk for intraoperative fracture of the femur because the magnification of the radiograph was larger than that of the template.

Tourniquet-induced wound hypoxia after total knee replacement.

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.

Cement as a risk factor for deep-vein thrombosis. Comparison of cemented TKR, uncemented TKR and cemented THR.

A total of 110 total knee replacements (TKRs) was randomised to receive either a cemented or an uncemented prosthesis. Postoperative venography at five to seven days was used to compare the prevalence, site and size of deep-vein thrombosis (DVT). We also compared the findings with those of postoperative venography in a group of patients with cemented total hip replacements (THRs). The total prevalence of DVT was significantly greater after uncemented (81%) than after cemented TKR (55%). Both knee groups had a significantly higher prevalence of DVT than in cemented hip replacements (32%). We found no difference in the proportion with proximal DVT in the three groups (14%, 15% and 16%). The median length of the thrombi was significantly greater after cemented (26.5 cm) than after uncemented TKR (11 cm) or after cemented THR (7 cm). This difference was mainly due to greater lengths of distal rather than proximal thrombi. We conclude that the use of cement may affect the formation of DVT after joint replacement, but does not appear to lead to an increased incidence.

The histopathology of de Quervain's disease.

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.

Screening for deep-venous thrombosis after hip and knee replacement without prophylaxis.

We performed routine venography after operation in a consecutive series of 252 patients with total joint arthroplasties in whom no form of routine chemical or mechanical prophylaxis had been used. The prevalence of deep-vein thrombosis (DVT) was 32% (16% distal, 16% proximal) after total hip replacement and 66% (50% distal, 16% proximal) after total knee replacement (p < 0.001). We did not treat distal DVT. There were only two readmissions within three months of surgery because of thromboembolic disease. There were two deaths within this period, neither of which was due to pulmonary embolism.

Bone marrow-derived cell populations in uterine and ectopic endometrium.

Uterine endometrium contains numerous bone marrow-derived cells. The spectrum of cell types is different from that of any other tissue, and the differences in endometrium from women with endometriosis may reflect a different endometrial phenotype in these women. The cell types of bone marrow origin found in ectopic endometrium may indicate the degree of differentiation of the tissue. It was found that, in normal endometrium, the CD45+ cell population comprised T cells, macrophages, CD56+ large granular lymphocytes, some CD16+ cells and a few B cells. Changes in these cell populations during the menstrual cycle were similar in endometrium from both controls and patients with endometriosis, and resembled that reported previously by others. In ectopic endometrium, the frequency of CD45+ cells remained within the same range as that of uterine endometrium but without any obvious pattern of change during the menstrual cycle. CD56+ large granular lymphocytes, an immune cell type characteristic of uterine endometrium, were also found in ectopic endometrium. Our results indicate that ectopic endometrium, as well as comprising both glandular and stromal cells, contains bone marrow-derived cell populations similar to those of uterine endometrium. This suggests that the same processes of cell migration and/or differentiation occur in ectopic and uterine endometrium.