The influence of oral L-arginine on fracture healing: an animal study

The known biological activities of nitric oxide suggest a role in bone healing. We hypothesized that L-arginine, a source of nitric oxide, expedites the healing process of stabilized diaphyseal defects.

Prospective blinded animal study.

Using a guinea-pig model, a 7 mm diaphyseal and periosteal defect was produced in the right femur and splinted intramedullary with a 1.4 mm K-wire. The guinea pigs (n = 44) were treated orally in three parallel groups: two treatment groups received high doses of L-arginine (one group for 2 weeks and the other for 4 weeks) and a control group received vehicle only. After four weeks, all animals were killed and both femora explanted. Radiological, histological, histomorphometric and mechanical evaluation was performed blinded.

Radiographs showed significantly more healing in the treatment groups (2 weeks, 10/15; 4 weeks, 11/15) than in the control group (3/14). The mechanical energy necessary for femur failure was significantly higher in the 4-week treatment group than in the control group (P < 0.05). Histology and histomorphometry showed significantly increased coverage of nonvascularized bone fragments with newly formed bone in the treatment groups (P < or = 0.05). The contralateral uninjured femora did not show significant differences between groups.

Oral L-arginine expedites healing in stabilized diaphyseal defects in guinea pigs without detrimentally affecting uninjured counterparts.