[Bone healing after oblique osteotomy of the metacarpus in 6-week-old calves after conservative treatment or osteosynthesis].

Bone healing in infants treated by a rigid osteosynthesis of AO type showed mostly a marked periosteal and endosteal callus formation. In adults a callus formation is seldom seen and primary bone healing is mainly based on direct conduction of Havarian channels. Periosteal callus formation is even judged as a sign of instability in adults. We did à 2:1 osteotomy of the right metacarpal bone in 48 calves of 6 weeks of age. The treatment consisted in reposition and a plaster (6) in osteosynthesis with a metal screw of AO type (6) or a biodegradable screw of polylactid (36). The animals were sacrified 1-6 weeks postoperatively and a histological study was done in a comparative way based on the most common criteria in the literature of osteology and traumatology. In calves bones healing takes about 4-6 weeks even if the treatment is conservative or if there is a progressive dislocation in the first two postoperative weeks. A periosteal and endosteal callus formation is seen in every instance, even after interfragmentary compression by metal or biodegradable screws. All the results of biodegradable screws are at least as good as with metallic screws, at least in the growing skeleton. The force applied for interfragmentary compression does not lead to primary bone healing in the growing skeleton of young calvess.