Vascularized Bone Grafting in a Canine Carpal Avascular Necrosis Model

Abstract

Background Limited experimental research has been performed on the treatment of avascular necrosis (AVN) by vascularized bone grafting. Questions/purposes A new model simulating carpal AVN was created to investigate surgical revascularization of necrotic bone. Methods In seven mongrel dogs, AVN was induced by removal of the radial carpal bones bilaterally, deepfreezing, coating in cyanoacrylate, and reimplantation. A reverse-flow vascularized bone graft from the distal radius was implanted in the avascular radial carpal bone. The contralateral side served as an untreated ischemic control. Bone blood flow, bone volume, radiography, histomorphometry, histology, and MRI were analyzed at 4 weeks. Results Blood flow was substantially higher in grafted bones when compared with controls (14.68 ± 15.43 versus 0.27 ± 0.28 mL/minute/100 g). Blood flow correlated with increased osteoid formation and higher levels of bone turnover. T1 and T2 signals on MRI did not correlate with quantitative bone blood flow measurements. Necrotic bones with no blood flow had normal T1 and T2 signals, whereas revascularized bones had signal changes when compared with adjacent carpal bones. No major collapse occurred in any radiocarpal bone. Conclusion In a canine experimental model, investigation of carpal AVN shows the ability of vascularized bone grafting to revascularize and remodel avascular bone. Clinical Relevance Surgical revascularization of necrotic bone induced by vascularized bone grafting results in increased bone perfusion and bone remodeling as compared with untreated necrotic bone. MRI T1 and T2 signals can be normal in necrotic avascular bone.

Primary medial femoral condyle vascularized bone graft for scaphoid nonunions with carpal collapse and proximal pole avascular necrosis

“…Preoperative radiographs and CT scans are used to assess carpal alignment, scaphoid deformity, proximal pole size, fragmentation, and arthritic changes. As MRI has not been shown to be a reliable method for assessing proximal pole vascularity, it is not routinely ordered (Willems et al., 2011). Instead, we rely on an intraoperative assessment of proximal vascularity as described by Green (1985).…”

Imaging Diagnosis—radiography and Computed Tomography of Radioulnar Ischemic Necrosis in a Jack Russell Terrier

“…Ischemic necrosis of the bone may result from intraluminal obstruction (e.g., thromboembolic disorders or stasis), vascular compression (e.g., external pressure or vasospasm), or disruption of vessels (e.g., trauma). In the dog, ischemic necrosis is encountered most commonly within the epiphysis (e.g., Legg‐Calve‐Perthés), followed by small bones of the carpus (e.g., idiopathic ischemic osteonecrosis of the carpal bone and the diaphysis (e.g., RUIN). In previous reports, the exact cause of ischemic osteonecrosis is unknown.…”

Radioulnar Ischaemic Necrosis in a Dog with Concurrent Osteomyelitis and Bone Sequestration

“…1 Osteonecrosis in dogs has also been reported to occur with Legg-Calves-Perthes, idiopathic osteonecrosis of the carpal bone and maxillofacial osteonecrosis. [2][3][4] This is the first case report of concurrent haematogenous osteomyelitis and ischaemic necrosis occurring at the site of a lesion that is radiographically consistent with RUIN.…”