Treatment of fracture of metacarpus in calves using autogenous rib graft

Abstract

The present study was conducted on 12 apparently healthy, crossbred male calves six to twelve months of age and weighing 50 to 80 kg, divided into two groups of six animals each (Group A and B). A transversa mid shaft fracture was created on the right metacarpus by open method under sedation with Triflupromazine hydrochloride at the rate of 0.25 mg/kg body weight IM and diazepam at the rate of 0.20 mg/kg body weight IV followed by local infiltration analgesia using two percent solution of lignocaine hydrochloride. In group A, the fracture was reduced and the fragments were retained in position by placing two freshly cropped autogenous rib grafts subperiosteally, one on the anterior aspect and the other on the posterior aspect of the metacarpus. The grafts were fixed in position by hemicerclage wiring using stainless steel wires at two places. The limb was immobilized with four cotton padded bamboo splints and plaster of paris cast. In group B, the fracture was reduced and the wounds were sutured. The limb was immobilised with four cotton padded bamboo splints and plaster of paris cast. A sham operation was performed on the left metacarpal region on the same day by incising the skin upto the periosteum and suturing it. By the end of the second week, all the animals could get up and lie down without assistance. Four animals of Group A and three animals of Group B started bearing weight on the fractured limb from varying periods. Favouring of the fractured limb, limping and nodding of the head were observed in all the animals. Pawing action with the fractured limb and stumbling were observed in two animals each from both the groups. Dragging of the toes was observed only in one animal, in group B. Infection and suppuration at the suture line was observed in one animal of group A. Plaster of paris cast remained intact throughout the period of observation in all the animals. One animal from group A and four animals from group B required reinforcement of plaster cast. Marked displacement of the distal fragment was noticed in one animal each in Group A and B. But deviation of the distal fragment at the fracture site was observed in one animal of Group A and four animals of Group B. Grafts were in position in all the animals throughout the the period of observation. They became radiographically indistinguishable from fourth week onwards. Radiographically visible callus was found by the third week in group A and by the first week in group B. Partial obliteration of the fracture gap was observed by the end of fourth week in both the groups. Fractured bone cropped after two weeks revealed mobility between the fragments in both the groups. The bones cropped after four weeks showed well developed callus uniting the fragments and there was no mobility at the fracture site in both the groups. The callus developed at the end of six weeks and four weeks were grossly similar in both the groups. Histological examination of the callus cropped at second week in group A revealed periosteal and capillary proliferation along with new trabecular bone formation around the graft site. In group B, fibrous tissue proliferation exceeded trabecular new bone formation. The callus cropped at fourth week in group A revealed extensive areas of graft vascularisation and zones of new bone formation. In group B, cartilage formation was seen along with zones of new bone formation and fibrous tissue proliferation. Replacement of the graft tissue with proliferating blood vessels, osseous tissue and connective tissue were observed in the callus cropped from the animals of group A, at the end of six weeks. In group B, well developed internal callus, extensive periosteal callus, proliferation of fibrous tissue and trabecular ossification centres were observed. Fibrocartilage was noticed in the callus in one animal of group B.