Effects of antihistamines on joint stiffness and bone healing after periarticular fracture.

In an effort to blunt the inflammatory response following injury, we studied the effects of antihistamines on joint stiffness and bone healing after periarticular fracture. The hind limbs of 37 New Zealand white rabbits were instrumented with intramedullary Steinmann pins to allow immobilization after creating a distal tibia fracture. After periarticular ankle fracture, the rabbits were divided into groups to receive chlorpheniramine, low-dose terfenadine, high-dose terfenadine, or no antihistamine. Antihistamine was administered for the first 5 days after fracture. At 3 weeks after fracture, the rabbits treated with antihistamines showed a significant reduction in joint stiffness compared to control animals. To determine if antihistamine also retarded bone healing, an additional 12 New Zealand white rabbits underwent bilateral drilling of the midshaft of the femur with a 2.5 mm Steinmann pin. Six animals received oral terfenadine, and six served as controls. After 5 weeks of cage activity, the animals treated with the antihistamine showed a significant decrease in energy to failure of the femurs on torsional testing. Qualitative microscopic examination revealed less mature callus at the site of the femoral cortical defect in those animals treated with the terfenadine. Antihistamine may have heretofore unconsidered benefits in preventing post-traumatic joint stiffness but may slow healing of associated bony injuries.