Poor prosthetic in shape is usually the consequence of heterotopic ossification
Poor prosthetic in shape is usually the consequence of heterotopic ossification (HO), a regular problem subsequent blast accidents for returning service members. frequency of HO (= 0.041, = ?0.622). This study demonstrates that the volume of HO and age may affect the voltage threshold necessary to improve current osseointegration procedures. due to variations in ion concentrations, temperature and hydration; variables which were not accounted for with this finite element model. Statistical Evaluation The volume of HO in each service members residual limb was compared to the optimal potential difference to determine whether ectopic bone growth correlated with the electric field and current density at the boneCimplant interface. HO formation was also independently assessed to determine whether demographical information (age, height, weight, residual limb length) correlated with the volume of HO since inconsistencies have been presented in the orthopedic literature.6,21 All the statistical evaluations were performed by computing Spearmans rho correlation coefficients and nonparametric statistical evaluations, given the limited sample size. In addition, in order to accurately associate the predictor and outcome measures, without introducing overfitting or having confounding variables, each factor was correlated independently. All the statistical comparisons were conducted with commercially available software and = 0.05 (SPSS, Inc., Chicago, IL, USA). RESULTS For all the reported E-3810 manufacture cases, voltage gradients at the boneCimplant interface were within the required range, and, therefore, the limiting factor for selecting the optimal potential difference for each service member was based on current density magnitudes (Fig. 7). Electric fields fluctuated from 1.30 to 3.10 V/cm for all the patients, a value which should theoretically induce osteoblast migration14 (Table 2). However, current densities ranged from 0.66 to 2.63 mA/cm2 for the potential differences selected and would require individual adjustments if this technology were to be implemented clinically (Fig. 8 and Table 3). FIGURE 7 Electric field (a) and current density (b) distributions for service member 2 using a potential difference of 2 volts. FIGURE 8 Current densities in the distal residual limb for the 2 2 volt potential difference are shown for each patient in the study. The critical threshold for current density (1.8 mA/cm2) is indicated by the horizontal dashed line. TABLE 2 Voltage gradients at the bone implant-interface given in units of V/cm. TABLE 3 Current densities at the bone-implant interface given in units of mA/cm2. Investigation of the current densities at the periprosthetic interface demonstrated lower current density magnitudes when the volume of HO increased (Fig. 8). For each potential selected in Subjects 2, 3, and 11, current densities remained below the 1.8 mA/cm2 threshold. In each of these cases, a dense aggregation E-3810 manufacture of HO was located at the anode site and resulted in more resistive medium at the point of current injection. This trend was consistent throughout the study and results of a Spearmans rho correlation coefficient, assessing the relationship MAP2K1 between the volume of HO and optimal potential difference, were statistically significant (= 0.024, = 0.670). The volume of HO was also compared to demographic information provided in the subjects medical E-3810 manufacture records to determine whether correlations existed between patient history and HO. While literature has speculated that the frequency of HO is dependent on genetic predispositions6 and body type, there is little evidence to directly support these claims. Our results indicated that only age was statistically significant (= 0.041, = ?0.622) and that the volume of HO decreased with increasing age. DISCUSSION Ectopic bone formation.