Development of a novel murine delayed secondary fracture healing in vivo model using periosteal cauterization

Abstract

IntroductionDelayed union and nonunion development remain a major clinical problematic complication during fracture healing, with partially unclear pathophysiology. Incidences range from 5 to 40% in high-risk patients, such as patients with periosteal damage. The periosteum is essential in adequate fracture healing, especially during soft callus formation. In this study, we hypothesize that inducing periosteal damage in a murine bone healing model will result in a novel delayed union model.Materials and methodsA mid-shaft femoral non-critically sized osteotomy was created in skeletally mature C57BL/6 mice and stabilized with a bridging plate. In half of the mice, a thin band of periosteum adjacent to the osteotomy was cauterized. Over 42 days of healing, radiographic, biomechanical, micro-computed tomography and histological analysis was performed to assess the degree of fracture healing.ResultsAnalysis showed complete secondary fracture healing in the control group without periosteal injury. Whereas the periosteal injury group demonstrated less than half as much maximum callus volume (p < 0.05) and bridging, recovery of stiffness and temporal expression of callus growth and remodelling was delayed by 7–15 days.ConclusionThis paper introduces a novel mouse model of delayed union without a critically sized defect and with standardized biomechanical conditions, which enables further investigation into the molecular biological, biomechanical, and biochemical processes involved in (delayed) fracture healing and nonunion development. This model provides a continuum between normal fracture healing and the development of nonunions.

Enhancement of fracture healing after citrulline supplementation in mice

“…The surgical procedure has previously been described by Grongroft et al (2019). In the first 2 d after surgery, mice received 0.1 mg/kg subcutaneous buprenorphine every 10-14 h as post-operative analgesia.…”

Amino acids and fracture healing

“…This increased fall risk may result in a higher risk for sustaining a fracture, hence it may contribute to the total number of nonunions developing in these trauma patients. A poor nutritional state increases the risk for osteoporotic fractures 51 and also of nonunion development as osteoporosis leads to a reduction of osteoblasts and callus production 22,52 . Next to osteoporotic fractures, mal/undernourished patients tend to have more fall incidents when compared to non-malnourished patients 53 .…”

“…The development of our in vivo murine femur osteotomy model with open reduction and internal plate-screw fixation provides an optimal continuum and intermediary between delayed union and either normal bone healing or nonunion development by additional usage of periosteal cauterization. Additionally, it can be used to investigate improvement or disturbance of bone healing processes resulting from pharmacologic, metabolic or genetic interventions 51 .…”

“…Mice lack an exact copy of the human system of Haversian canals which might be considered as a limitation although a comparable mechanism using resorption cavities is present 59,60 . A main advantage of mice is the benefit of being easily genetically modifiable which enables deletion of selected genes coding for specific enzymes that might influence the metabolism of interest 51 .…”

“…Our first study describes the influence of absence of the endothelial and inducible nitric oxide synthases on bone healing in this model 51 of delayed union development. Deletion of either of these genes in mice resulted in transition of delayed union into nonunion of the femur osteotomy 61 .…”