Biomaterials for Orthopedic Surgery in Osteoporotic Bone: A Comparative Study in Osteopenic Rats

To evaluate orthopedic devices in pathological bone, an experimental study was performed by implanting Titanium (Ti) and Hydroxyapatite (HA) rods in normal and osteopenic bone. Twenty-four rats were used: 12 were left intact (Control: C) while the other 12 were ovariectomized (OVX). After 4 months all the animals were submitted to the implant of Ti or HA in the left femoral condyle (Ti-C, HA-C, Ti-OVX, HA-OVX). Two months later the animals were sacrificed for histomorphometric, ultrastructural and microanalytic studies. Our results show a significant difference between the Affinity Index (A.I.) of HA-C and Ti-C (77.0 ± 7.4 vs 61.2 ± 9.7) (p < 0.05). No significant differences were observed between the osteointegration of Ti-C and Ti-OVX (61.2 ± 9.7 vs 48.2 ± 6.7). Significant differences also exist between the osteointegration of HA-C and HA-OVX (77.0 ± 7.4 vs 57.6 ± 11.5) (p < 0.01). Microanalysis shows some modifications in Sulphur (S) concentration at the bone/biomaterial interface of the Ti-OVX group. Therefore our results confirmed the importance of biomaterials characteristics and of bone quality in osteointegration processes.

Shock Wave Therapy as an Innovative Technology in Skeletal Disorders: Study on Transmembrane Current in Stimulated Osteoblast-Like Cells

Extracorporeal shock wave treatment (ESWT) is successfully used in various musculoskeletal disorders and pathologies. Despite the increasing use of this kind of therapy, some aspects of its mechanism of action are still unclear. In vitro bone cell behavior under ESWT were previously investigated by the present author and MG63 osteoblast-like cells showed an enhancement in proliferation and in the osteoblast differentiation after therapy with a low-energy flux density. The aim of the present study was to evaluate the effect of ESWT on the permeabilization of cell membrane. We characterized physiological changes in the MG63 associated with ESWT generated by an ESW device and patch clamp recording was performed to study ion channels. Experiments were carried out using the whole-cell recording configuration of the patch-clamp technique and the ionic current measurements were performed on cell samples of ESW treated and control groups. The patch-clamp technique showed the effect of ESWT on the amplitude of transmembrane currents. The treatment with ESW enhanced the transmembrane current as well the voltage dependence of Ca-activated and K channels that mediate these currents: the differences between treated cells and control at 80mV were over 1000 pA (P<0.05). These modifications of ion channels activity positively influence cell proliferation (MTT test, P<0.0001) without interfering with the normal synthesis activity of stimulated osteoblasts.

Sonographic evaluation of entheseal sites of the lower extremity in patients undergoing hemodialysis

PURPOSE

To evaluate the entheseal sites of the lower extremities in patients on hemodialysis using the Glasgow Ultrasound Enthesitis Scoring System (GUESS) and to correlate the findings with the duration of hemodialysis and patient scores.

METHODS

Forty-nine patients who were on hemodialysis for at least 2 years were grouped according to duration of hemodialysis. Total GUESS scores; total enthesophyte, erosion, and bursitis scores; and tendon thicknesses were calculated, compared between groups, and correlated with duration of dialysis.

RESULTS

There was a statistically significant correlation between duration of hemodialysis and total GUESS score (p < 0.001, r = 0.81) and also between the total enthesophyte and erosion scores (p < 0.001). If severe enthesitis was defined as a total GUESS score of more than 18, receiver operating characteristic (ROC) curve analysis revealed that a cutoff point of 10 years for the duration of hemodialysis would predict severe enthesal damage with 83% sensitivity and 93% specificity (area under the ROC curve, 0.92; 95% confidence interval, 0.83-1.00).

CONCLUSION

Hemodialysis results in entheseal site changes that worsen with extended duration of hemodialysis, especially after 10 years.

Vintage, nutritional status, and survival in hemodialysis patients

BACKGROUND

The link between dialysis "vintage" (length of time on dialysis in months to years) and survival has been difficult to define, largely because of selection effects. End-stage renal disease (ESRD) is thought to be a wasting illness, but there are no published reports describing the associations between vintage and body composition in hemodialysis patients.

METHODS

We explored the relationships among vintage, nutritional status, and survival in a 3009 patient cohort of prevalent hemodialysis patients. Body weight, total body water, body cell mass, and phase angle by bioelectrical impedance analysis were the body composition parameters of interest. We examined vintage as an explanatory variable in multiple linear regression analyses (adjusted for age, gender, race, and diabetes) using body composition parameters and biochemical indicators of nutritional status as dependent variables. Proportional hazards regression was used to evaluate the association of vintage and survival with and without adjustment for case mix and laboratory variables.

RESULTS

Dialysis vintage was 3.8 +/- 3.7 (median 2.6) years. Body composition parameters tended to be lower after dialysis year 2. Linear estimates per year of vintage beyond year 2 include -0.66 kg body wt (P < 0.0001), -0.17 kg total body water (P = 0.0003), -0.14 kg body cell mass (P < 0.0001), and -0.07 degrees phase angle (P < 0.0001). In unadjusted analyses, vintage was not associated with survival, either as a linear or higher order term. The adjustment for case mix yielded a vintage term associated with an increased relative risk (RR) of death (RR 1.04 (95% CI, 1.01 to 1.07 per year). A further adjustment for laboratory data yielded a RR of 1.06 (95% CI, 1.03 to 1.09 per year).

CONCLUSION

Dialysis vintage is related to nutritional status in hemodialysis patients, with vintage of more than years associated with a significant decline in all measured nutritional parameters. Cross-sectional analyses probably underestimate these effects. A year accrued on dialysis is associated with a 6% increase in the risk of death, all else equal. Longitudinal assessments of nutritional status, including body composition, are required to better understand the natural history of wasting with ESRD and its implications for long-term survival.