Slightly focused high-energy shockwave therapy: a potential adjuvant treatment for osteoporotic fracture

Slightly focused high-energy shockwave (HESW) therapy is characterized by a wide focal area, a large therapy zone, easy positioning and less pain during treatment. The objective of this study was to perform for the first time an in vivo test of the slightly focused HESWs for osteoporotic fractures. Bilateral proximal tibial osteotomies were made in 30 ovariectomized (OVX) Sprague-Dawley rats and secured with internal fixation. The osteotomy site in the left tibia was subsequently treated with slightly focused HESWs with the energy flux density of 0.26 mj/mm(2), shock repetition frequency of 1 Hz and 2000 shocks (OVX + HESW group). The contralateral right tibia was not treated and served as the control (OVX group). Roentgenographic examination 2, 4, 6, and 8 weeks after osteotomy showed that HESW treatment accelerated tibia fracture healing in osteoporotic rats. Histological examination 2, 4, and 8 weeks after HESW treatment showed a greater inflammatory reaction in the OVX + HESW group, with more mature collagen and trabeculae than in the OVX group. Micro computer tomography (Micro-CT) scanning after 4 and 8 weeks showed that bone volume (BV), bone volume/tissue volume (BV/TV), mean trabecular thickness (Tb.Th), and mean trabecular number (Tb.N) were about 45.0% and 33.1%, 18.4% and 20.1%, 38.2% and 20.9%, 26.7% and 28.4%, respectively, higher in the treatment group than in the control group (P < 0.05); and the mean trabecular separation (Tb.Sp) was about 16.7% and 27.3% lower in the treatment group (P < 0.05). Four and eight weeks after HESW treatment, the maximum compressive callus endurance was about 72.3% and 25.5%, respectively, higher in the treatment group than in the control group (P < 0.05). These results show that slightly focused HESW therapy has a beneficial effect on osteoporotic tibial fracture healing. Slightly focused HESWs could increase callus endurance, induce bone formation, and improve trabecular bone microarchitecture and biomechanical properties.