The effects of subperiosteal and extraperiosteal dissection on the
healing of tibial osteotomies were studied in fourteen rabbits killed three
weeks after the osteotomy. Of the tibiae exposed subperiosteally, 71 per
cent healed; of those exposed extraperiosteally, only 7 per cent had solid
union. The first group had a significantly lower level of hydroxyproline in
the callus and higher values for breaking load, breaking strength, and
absorption of energy to failure. In ten animals that also had muscle
transection at the osteotomy site, the rate and type of healing was similar
whether no dissection, subperiosteal dissection, or extraperiosteal
dissection had been done, but the callus showed lower calcium levels and
higher hydroxyproline levels than in either of the groups with muscle
trauma. This implies retardation of healing caused by muscle injury. Our
data suggest that in the absence of muscle damage, subperiosteal dissection
results in earlier healing than does extraperiosteal dissection. Muscle
transection markedly retards healing; then, after transection, neither type
of dissection appears to retard healing more than the other.