The direct relationship between bone strain and electric fields has spurred continual interest in the field of bioelectricity over the past 160 years. It has been reported that stress-generated potentials alter cell proliferation and extracellular matrix secretion. The observation that endogenous electrical signals facilitate osteoinduction has lead to high production of electrical stimulation devices to fix bone defects. Despite the reported 100,000 nonunions healed as of 1990 with electrical stimulation, skepticism due to lack of homogeneity with trial design and dosage still exists within the scientific community. It is the purpose of this review to assess the bioelectric phenomenon of bone as it applies to piezoelectricity, fracture healing, and overall changes in bone metabolism which occur with controlled electrical stimulation.

(1) standardize TBI diagnostic criteria; (2) classify TBI according to mechanism and severity; (3) categorize TBI symptoms as somatic, psychological, or cognitive; and (4) systematize types of care given during the acute and rehabilitation stages of TBI treatment. Polytrauma and associated psychological and neurologic conditions may create barriers to optimal rehabilitation from TBI. Given the completion of recent combat operations and the transition of TBI patients into long-term care within the US Department of Veterans Affairs system, a review of the literature concerning TBI is timely. Long-term follow-up care for patients who have sustained TBI will remain a critical issue for the US military.

Direct skeletal fixation, termed osseointegration, has expanded in the last century and includes use in total joint replacements, the edentulous mandible and maxilla, and percutaneous osseointegrated prosthetics. Although it is well known that titanium and bone have the ability to form a durable bone-implant interface, new applications have emerged in the field of orthopedics, which requires a more thorough assessment of the literature. This review aims to introduce the basic biological principles for attaining osseointegration and discusses the major factors for assuring successful cementless fixation.

Poor prosthetic fit is often the result of heterotopic ossification (HO), a frequent problem following blast injuries for returning service members. Osseointegration technology offers an advantage for individuals with significant HO and poor socket tolerance by using direct skeletal attachment of a prosthesis to the distal residual limb, but remains limited due to prolonged post-operative rehabilitation regimens. Therefore, electrical stimulation has been proposed as a catalyst for expediting skeletal attachment and the bioelectric effects of HO were evaluated using finite element analysis in 11 servicemen with transfemoral amputations. Retrospective computed tomography (CT) scans provided accurate reconstructions, and volume conductor models demonstrated the variability in residual limb anatomy and necessity for patient-specific modeling to characterize electrical field variance if patients were to undergo a theoretical osseointegration of a prosthesis. In this investigation, the volume of HO was statistically significant when selecting the optimal potential difference for enhanced skeletal fixation, since higher HO volumes required increased voltages at the periprosthetic bone (p = 0.024, r = 0.670). Results from Spearman’s rho correlations also indicated that the age of the subject and volume of HO were statistically significant and inversely proportional, in which younger service members had a higher frequency of HO (p = 0.041, r = −0.622). This study demonstrates that the volume of HO and age may affect the voltage threshold necessary to improve current osseointegration procedures.