N-terminal telopeptides of type I collagen and bone mineral density for early diagnosis of nonunion: An experimental study in rabbits

BACKGROUND: The diagnosis and treatment of bone nonunion have been studied extensively. Diagnosis and treatment of nonunion are mainly performed based on the interpretation of clinico-radiographic findings, which depend on the clinician's experience and the degree of bone callus formation during the fracture-healing process. However, resolution may be compromised when the bone mineral content is <25%. A feasible method of monitoring bone-healing is therefore needed. We monitored a rabbit model of bone nonunion by regular radiographic examinations, QCT detection, and biomarker concentrations. MATERIALS AND METHODS: Twenty purebred New Zealand rabbits (10 male and 10 female, 5–6 months of age, 2.5–3.0 kg) were divided into bone defect Group (I) that 10 left radius bones underwent resection of 1.5 cm of mid-radius bone and bone fracture Group (II) that another 10 left radius bones underwent only mid-radius fracture. Quantitative computed tomography detection of bone mineral density (BMD) and serum markers of bone formation (osteocalcin [OC], bone-specific alkaline phosphatase) and bone resorption (C- and N-terminal telopeptides of type I collagen (NTX) and tartrate-resistant acid phosphatase 5b) were assayed. There are twenty rabbits (10 male and 10 females). The age was 5–6 months weighing 2.5–3.0 kg). The defect was created in middle 1/3 radius in 10 rabbits and fracture was created in middle 1/3 radius of 10 rabbits. RESULTS: BMD and NTX concentrations were significantly lower at 5 weeks postoperatively compared to the preoperative values and were significantly different between the two groups. OC showed no significant difference before and after surgery. CONCLUSIONS: BMD and NTX concentrations may be useful for early detection of bone nonunion in rabbits.