The Effect of Tricyclic Antidepressants on Fracture Healing: An Experimental Study

Disorders of mood and post-traumatic stress disorder (PTSD) are common after major trauma, and one of the treatments used is Tricyclic Antidepressants (TCA). These medications work by inhibiting the re-uptake of neurotransmitters like serotonin and noradrenaline. Serotonin is known to have measurable effects on bone tissue due to the presence of specific receptors on bone cells. However, there are conflicting reports about how serotonin signaling affects bone tissue and the process of fracture healing. This study aimed to evaluate the effect of TCAs on fracture healing.

Twelve skeletally mature Wistar rats were used in the study. All rats underwent intra-medullary pinning of the right tibia, and a complete mid-diaphyseal fracture was created. The rats were then randomly split into two groups: a control group and a study group. For twenty-eight days, the study group received a daily dose of 10 mg/kg of amitriptyline via intraperitoneal infusion, while the control group received an equal volume of plain saline via the same route. On day twenty-eight, five hours after the final dose, all rats were euthanized to assess fracture healing using radiological, microscopic, and histological methods.

The study found a significant difference in the total volume of new bone formation between the two groups on day twenty-eight. The control group had a mean bone formation volume of 1.077 mm³, whereas the amitriptyline-treated group had a significantly higher mean volume of 1.824 mm³ (p<0.01).

The results suggest that TCAs positively influence the early phases of fracture healing. The increased new bone formation observed in the amitriptyline group indicates a potential therapeutic benefit beyond their known psychiatric effects. This finding adds to the existing literature on the complex relationship between serotonin signaling and bone metabolism, providing evidence that this class of antidepressants may enhance the process of bone repair.

Tricyclic Antidepressants, specifically amitriptyline, significantly increase new bone formation in the early stages of fracture healing in Wistar rats.