The efficacy of cylindrical titanium mesh cage for the reconstruction of a critical-size canine segmental femoral diaphyseal defect

Abstract

ABSTRACT:The authors developed a novel technique for the reconstruction of large segmental long bone defects using a cylindrical titanium mesh cage (CTMC). Although the initial clinical reports have been favorable, the CTMC technique has yet to be validated in a clinically relevant large animal model, which is the purpose of this study. Under general anesthesia, a unilateral, 3-cm middiaphyseal segmental defect was created in the femur of an adult canine. The defect reconstruction technique consisted of a CTMC that was packed and surrounded with a standard volume of morselized canine cancellous allograft and canine demineralized bone matrix. The limb was stabilized with a reamed titanium intramedullary nail. Animals were distributed into four experimental groups: in Groups A ,B, and C (six dogs each), defects were CTMC reconstructed, and the animals euthanized at 6, 12, and 18 weeks, respectively; in Group D (three dogs), the same defect reconstruction was performed but without a CTMC, and the animals were euthanized at 18 weeks. The femurs were harvested and analyzed by gross inspection, plain radiography, computed tomography (CT), and single photon emission computed tomography (SPECT). The femurs were mechanically tested in axial torsion to failure; two randomly selected defect femurs from each group were analyzed histologically. Groups A, B, and C specimens gross inspection, plain radiography, and CT, demonstrated bony restoration of the defect, and SPECT confirmed sustained biological activity throughout the CTMC. Compared to the contralateral femur, the 6-, 12-, and 18-week mean defect torsional stiffness was 44.4, 45.7, and 72.5%, respectively; the mean torsional strength was 51.0, 73.6, and 83.4%, respectively. Histology documented new bone formation spanning the defect. Conversely, Group D specimens (without CTMC) demonstrated no meaningful bone formation, biologic activity, or mechanical integrity at 18 weeks. The CTMC technique facilitated healing of a canine femur segmental defect model, while the same technique without a cage did not. The CTMC technique may be a viable alternative for the treatment of segmental long bone defects. ß

Custom-made composite scaffolds for segmental defect repair in long bones

“…These critical-sized defects are defined as the smallest size intraosseous wound in a particular bone and species of animal that will not heal spontaneously during the lifetime of the animal. Apart from size, a critical defect in long bones is influenced by factors such as species, anatomical location, associated periosteum and soft tissue, and biomechanical conditions in addition to age, metabolic and systemic influences and related comorbidities [26]. In Fig.…”

Animal Models for Evaluation of Bone Implants and Devices

“…Critical-size defects in animal models are defined as ''the smallest size intraosseous wound in a particular bone and species of animal that will not heal spontaneously during the lifetime of the animal'' 27,67 or a defect with <10% bone regeneration over the animal's lifetime. 27 Surgically created critical defects are a gap in length >2.25 times the diameter of the affected bone 26,46 or large cylindrical defects in femoral condyles or tibial metaphysis. Rats, rabbits, and increasingly small ruminants are used in defect models.…”

Outcome of the intramedullary diaphyseal segmental defect fixation system for bone tumors

“…Despite the potential complications including mechanical failure and infection [30], megaprostheses including segmental diaphyseal implants [22,31,32] or interposition metallic spacers [33][34][35][36] remain the main option for reconstruction after limb salvage surgery for bone tumors with up to 68% 10-year survival [19,[37][38][39]. Their advantages include preservation of the physes in children, preservation of joint function, immediate postoperative stability, early weight-bearing and rapid rehabilitation, off-the-shelf availability, and low infection rate [13,14,16,19,30,37,38,[40][41][42][43].…”