PERFORATIONS IMPROVE REHABILITATION OF MASSIVE CORTICAL GRAFTS: AN EXPERIMENTAL SHEEP MODEL

Abstract

Purpose: Only very partial integration of massive allografts is generally achieved, affecting bone-graft junctions and the peripheral cortical. In clinical practice, this is not a major problem for massive reconstructions with a sleeve prosthesis but can be a handicap for junctional grafts or osteoarticular grafts where weak recolonisation can be a source of complications.

Material and methods: Extraperiosteal resection measuring 5 cm in length was made in the mid shaft region and bridged by a cyropreserved non-irradiated allograft before stabilisation with a static locked nail. Three groups of ten sheep were studied. The first group received a simple allograft without perforation; the allograft was perforated in the second group (1.1 mm drill bit); and the perforations in the allograft in the third group were lined with decalcified bone powder with assumed potential for inducing bone growth. The implantation was studied after a delay of six months. There were three infections so the analysis was made on 27 grafts. Plain x-rays (consolidation of the graft-bone junctions), histomorphometrics (porosity, new peripheral and endomedullary bone deposit, cortical thickness), and bone density were studied.

Results: Rate of bone-graft consolidation was not significantly different in the three groups. The callus was more endosteal in groups 2 and 3 (p< 0.02) and endomedullary bone deposit was greater (p=0.0001) than in group 1 without perforation. There was approximately three times more bone deposit in the perforated allografts than in the non-perforated allografts; Adjunction of demineralised bone around the perforated grafts did not lead to any significant difference compared with the perforated allografts (group 2).

Discussion: Significantly more bone deposit observed with perforated allografts should lead to better biomechanical behaviour. This is being tested in further work.

Conclusion: Perforations induce a significant increase in new bone deposit in massive cortical allografts, remodelling is much more active and extensive than with non-perforated allografts. It would be logical to propose perforated allografts for junctional or osteochondral massive cortical grafts.