Bone impact microindentation for preoperative in vivo assessment of bone strength in orthopedic surgery: a case report

Portable bone impact microindentation devices are a novel generation of diagnostic instruments allowing direct in vivo assessment of cortical bone strength. The assessment involves application of a single impact cycle on the bone and measurement of tissue response to the applied force in relation to a reference value adjusted for age and sex. Here, we report the case of a male patient, aged 66 years, who underwent a cementless right total hip replacement for the treatment of monolateral osteoarthritis, during which an incomplete spiral fracture of the proximal metaphysis of the femur occurred. The patient had no history of bone fragility, and preoperative evaluation by radiofrequency echographic multi spectrometry showed mild osteopenia at both the lumbar spine and the femoral neck, suggesting he had a relatively low risk of fragility fracture. Conversely, preoperative impact microindentation analysis, performed using the OsteoProbe device on the left tibia, showed extremely low bone resistance (average bone score of 58.4, versus the adult male normal value of 84.4 ± 7.0). Our case report suggests that bone strength evaluation by bone impact microindentation may potentially predict individual fracture risk not shown by bone mineral density assessment alone. KEY WORDS: Bone strength, bone impact microindentation, individual fragility fracture risk, diagnosis of bone fragility.