Osteogenesis and Histostructure of Femoral Muscles When Modeling a Femoral Fracture with Immediate or Delayed Osteosynthesis Using an Interlocking Intramedullary Antegrade Rod

Abstract

Interlocked intramedullary osteosynthesis is the most common method for treating femoral shaft fractures. The aim — to reveal specifi c characteristics of the histostructure of canine femoral muscles when healing femoral fractures under osteosynthesis using interlocking intramedullary reinforcement with an antegrade metal rod. Femoral shaft fractures were modelled in 9 mongrel dogs. The fractures were fi xed with an intramedullary rod. In Group I (n=4), osteosynthesis was started immediately after bone injury. In Group II (n=5), osteosynthesis was started 4 days after fracture (delayed osteosynthesis). M. biceps femoris and M. quadriceps femoris were studied. In Group I and Group II, bone healing occurred following 42 and 70 days, respectively. A unifi ed bone marrow cavity and cortical layer had been formed by day 70 and day 100 in Group I and Group II, respectively. The histostructure of M. quadriceps femoris in Group I remained largely unchanged throughout the experiment, while M. biceps femoris underwent the process of structural reorganization on days 42 and 70 of the experiment. The Group of delayed osteosynthesis demonstrated changes in the histostructure of both muscles, including an increased diversity of fi bre diameters, an increased number of nuclei in myocytes, fi brosis of the interstitial space and perimysial arterial vessels. These changes were more pronounced in M. biceps femoris. Three months after injury, the histostructure of the muscles under study, even in the Group of delayed osteosynthesis, had no signifi cant differences and tended to the intact norm. In femoral fractures, the earliest possible fi xation of bone fragments with an inter locking antegrade intramedullary rod is recommended. A complete bone healing in such cases occurs a month earlier than in those with delayed osteosynthesis. The femoral muscles of the anterior group are injured to a lesser extent than those of the posterior group.