The Effect of Levodopa or Levodopa-Carbidopa (Sinemet) on Fracture Healing

OBJECTIVESLevodopa (L-dopa) and L-dopa/carbidopa were evaluated to determine their effectiveness in the stimulation of bone healing of fractures at risk for nonunions. METHODSForty-two retired breeder female Sprague-Dawley rats were divided into 2 experimental groups and 1 control. Thirty-six rats were evaluated for results. The right femur of each rat was fractured and an intramedullary omega pin was inserted to create a 2 mm bone gap. The rats were administered either 0.2 g/kg/d of L-dopa, 0.2/0.02 g/kg/d L-dopa/carbidopa in their feed, or plain powdered chow (Sham control group). The rats were killed at 5 weeks postsurgery. The femurs were excised, radiographed, and mechanically tested. Bone healing was assessed. Bone stiffness, ultimate load, and energy to failure were determined under 3 point bending using an Instron materials testing system. RESULTSThe femurs of 30% of the Sham rats healed compared with 50% of the L-dopa/carbidopa and 84% of the L-dopa treated femurs. The healed L-dopa rat femurs had significantly greater ultimate load (P=0.037) and energy to failure (P=0.004) than the healed Sham rats. There were no significant differences between the L-dopa/carbidopa group and either the Sham or L-dopa group. CONCLUSIONSThese results confirm that L-dopa administration increases the healing in nonunion fractures. The combination of L-dopa/carbidopa did not significantly increase fracture healing.