Treatment of a Large Tibial Non-Union Bone Defect in a Cat Using Xenograft with Canine-Derived Cancellous Bone, Demineralized Bone Matrix, and Autograft

A 17-month-old domestic short-hair cat was referred due to a non-union in the left tibia. The initial repair, conducted 3 months prior at another animal hospital, involved an intramedullary (IM) pin and wire to address a comminuted fracture. Unfortunately, the wire knot caused a skin tract, resulting in osteomyelitis. Although the wire knot was removed at that hospital, the draining tract persisted, continuously discharging exudate. Upon evaluation, the first surgery was reassessed and revised, involving the removal of the IM pin and the application of external skeletal fixation alongside an antibiotic susceptibility test. After 118 days post-revision surgery, while some cortical continuity was observed, a significant bone defect persisted, posing a substantial risk of refracture should the implant be removed. A second revision surgery was performed, utilizing a bone plate combined with cancellous bone autograft, recombinant human bone morphogenetic protein-2, and xenograft featuring a canine-derived cancellous chip mixed with demineralized bone matrix. Remarkably, the bone completed its healing within 105 days following the subsequent surgery. Radiography demonstrated successful management of the large bone defect up to the 2-year postoperative check-up. During telephone follow-ups for 3.5 years after surgery, no complications were identified, and the subject maintained a favorable gait.