Neuromuscular electrical stimulation enhances fracture healing: results of an animal model

Neuromuscular electrical stimulation (NMES) could simulate physiological muscle functions known to be associated with the normal bone healing process. The object of the present study was to evaluate the effect of NMES on fracture healing, using an animal model. Thirty rabbits received unilateral, transverse, mid-tibial, 3-mm gapped osteotomies that were stabilized with double-bar external fixators. The femoral vein was ligated to induce venous stasis. From the fourth post-operative day, the study group was treated with 1 h daily of NMES for four weeks, while the control group was treated without NMES. For NMES, two surface electrodes were used: one above the patellar tendon and another around the lateral thigh. Callus area and mineral content at the osteotomy gap were measured, biweekly, using computerized tomographic examinations. Biomechanical properties of healing were evaluated with a torsion test, eight weeks after the index operation. Osteotomies treated with NMES exhibited 31% (p=0.01) higher mineral content and 27% (p=0.009) larger callus area than control osteotomies at eight weeks. The maximum torque, torsional stiffness, angular displacement at maximum torque, and energy required to failure of specimens in the study group were 62% (p=0.006), 29% (p=0.03), 34.6% (p=0.008), and 124% (p<0.0001) higher, respectively, than those in the control group at eight weeks. The results of the present study demonstrated that the use of NMES can enhance callus development and mineralization, with the consequent improvement in biomechanical properties of the healing bone.