Faculty Bibliography

We investigated the role of zoledronic acid on the regenerate and native bone after consolidation and removal of the external fixator in a rabbit model of distraction osteogenesis using 28 New Zealand white rabbits. The rabbits were randomly distributed into two groups. The first group received three doses of zoledronic acid (ZA) 0.1 mg/kg subcutaneously at weekly intervals while the second group received injections of sterile saline. Distraction started on day 7 at a rate of 0.8 mm/day for 12 days. At week 3 the average lengthening, regenerate density, and regenerate continuity were comparable between the two groups. At week 11 the regenerate in the treated group had a significant increase in Bone Mineral Density (BMD) and Bone Mineral Content (BMC) compared to the placebo group. On axial compression, the regenerate showed an increase in the peak load and a higher modulus of elasticity in the treated group. At 6 months, radiographs demonstrated signs of osteopenia of the proximal metaphysis in the control group, and failure of new bone formation around the pin sites in the treated group. BMC and BMD value differences between the two groups were not statistically significant. Histologically, there was persistence of more bone trabeculae in the medullary canal of the regenerate with the persistence of the pin-holes in the treated group. Mechanically, the regenerates in the treated group remain stronger in resisting the axial compression. The proximal fragment in the treated group exhibited a statistically significant decrease in the peak load, toughness and efail %. In conclusion, bisphosphonate-treated rabbits have a stronger regenerate during distraction, and directly after removal of the fixator. They do not develop disuse osteopenia in their lengthened tibia. This treatment may shorten the time in the external fixator and prevent fragility fractures in the treated extremity. However, its long-term safety has not yet been established.

Novel biomechanical methods have been developed to objectively measure acute fracture severity (from inter-fragmentary surface area) and chronic contact stress challenge (from patient-specific finite element analysis) in articular fractures. These new methods help clarify the pathomechanics of the development of post-traumatic osteoarthritis, and can contribute directly to the clinical care of patients. In this manuscript, the value of these two new measures is demonstrated in three illustrative tibial plafond fracture cases, in which both metrics are correlated with cartilage status and with patient outcomes at a minimum of two years after injury. These clinical cases demonstrate the utility of new biomechanical variables to advance clinical research and patient care, by providing a basis to predict outcome and select treatment.

INTRODUCTION/BACKGROUND:We evaluated the local recurrence rate (LRR) of bone sarcoma along the core-needle biopsy (CNB) tract in patients who underwent limb Salvage Surgery (LSS) following a diagnostic CNB performed irrespective of the planned surgical incision site and for which surgery did not involve any biopsy tract removal. METHODS:A retrospective review of 10 pediatric patients diagnosed with bone sarcoma using a computed tomography-guided core-needle biopsy, with evaluation of medical records, pathological specimens and radiological films from the date of diagnosis until the most recent follow-up. RESULTS:None of the patients experienced local recurrence during their follow up, despite the lack of biopsy site resection. CT scans of the involved extremities were negative for any suspicious lesions in all patients up until the most recent follow-up. CONCLUSIONS:Our study and review of the literature suggest that the incidence of tumor seeding the CNB tract in bone sarcoma patients is apparently low, and possibly negligible. CNB should be performed through the most direct approach to the tumor, and LSS can be performed safely through the standard approaches without excision of the biopsy tract.