Evading the host response: Staphylococcus “hiding” in cortical bone canalicular system causes increased bacterial burden

Extremity reconstruction surgery is increasingly performed rather than amputation for patients with large-segment pathologic bone loss. Debate persists as to the optimal void filler for this “limb salvage” surgery, whether metal or allograft bone. Clinicians focus on optimizing important functional gains for patients, and the risk of devastating implant infection has been thought to be similar regardless of implant material. Recent insights into infection pathophysiology are challenging this equipoise, however, with both basic science data suggesting a novel mechanism of infection of Staphylococcus aureus (the most common infecting agent) into the host lacunar–canaliculi network, and also clinical data revealing a higher rate of infection of allograft over metal. The current translational study was therefore developed to bridge the gap between these insights in a longitudinal murine model of infection of allograft bone and metal. Real-time Staphylococci infection characteristics were quantified in cortical bone vs metal, and both microarchitecture of host implant and presence of host immune response were assessed. An orders-of-magnitude higher bacterial burden was established in cortical allograft bone over both metal and cancellous bone. The establishment of immune-evading microabscesses was confirmed in both cortical allograft haversian canal and the submicron canaliculi network in an additional model of mouse femur bone infection. These study results reveal a mechanism by which Staphylococci evasion of host immunity is possible, contributing to elevated risks of infection in cortical bone. The presence of this local infection reservoir imparts massive clinical implications that may alter the current paradigm of osteomyelitis and bulk allograft infection treatment.

Technique for Failed Total Wrist Arthroplasty Conversion to a Total Wrist Arthrodesis with Allograft Interposition

The frequency of prosthetic total wrist arthroplasty continues to increase. With this increase comes the expected subsequent increase in need for revision or salvage procedures. The technique presented here involves the use of a cortical allograft interposition graft to restore bone stock and length for failed total wrist arthroplasty.

Clinical efficacy of autogenous cancellous bone and fibroblast growth factor 2 combined with frozen allografts in femoral nonunion fractures

SummaryObjectives: To evaluate the efficacy of cortical allograft and fibroblast growth factor 2 (FGF-2)-impregnated autogenous cancellous bone in nonunion fracture repair in dogs.Methods: From January 2000 to August 2010, seven dogs underwent cortical allograft and FGF-2-impregnated autogenous cancellous bone implantation for treatment of a femoral nonunion following fracture. Radiographic images were used to assess healing.Results: The average length of the implanted cortical allograft was 29.1 ± 4.4 mm. A significant improvement in the postoperative percentage of femoral shortening was observed with the experimental treatment, from 85.2 ± 8.2% to 95.0 ± 4.8%. Using radiographic scoring, we analysed the process of bone remodelling. At three months post-surgery, the proximal and distal fracture lines had begun to disappear, and a complete absence was observed after six months. Bacterial infection was detected in two of the seven cases.Clinical significance: The findings of our study suggest that the combination of cortical allografts with FGF-2 impregnated cancellous autograft may be useful in cases of diaphyseal fracture non-union. The disappearance of the fracture line in dogs with nonunion was recognized at the same phase as the report in which healing process of allograft was evaluated in the experimental ostectomy model using the normal dog.