Porous hydroxyapatite as a bone graft substitute in diaphyseal defects: A histometric study

Abstract

Porous hydroxyapatite (IP200), formed by conversion of the Poritidae porites exoskeleton, has pores averaging 230 microns and pore interconnections averaging 190 microns in diameter. In the distal radial diaphyses of 14 dogs, bilateral 7.5 X 20 mm cortical windows were created and fitted with 5 X 7.5 X 20 mm blocks of IP200 implants and iliac autografts. Both implanted and contralateral grafted radius specimens were retrieved at 3, 6, 12, 24, and 48 months. Unstained undecalcified sections were examined by microradiography and UV epi-illumination. Stained undecalcified sections were examined by light microscopy and quantitated by histometric methods. Implant specimens demonstrated good union and bone ingrowth at all time intervals. The implant specimens were composed of (mean +/- SE) 10.6% +/- 1.0% soft tissue, 51.2% +/- 1.3% bone, and 38.2% +/- 1.0% IP200. The graft specimens showed good union with little apparent ingrowth at 3 months, followed by progressive appositional closure of cancellous spaces. The graft specimens contained 21.9% +/- 0.9% bone at 3 months with increases at each time interval to 73.1% +/- 8.7% at 48 months. The volume fraction and mean width of IP200 did not change with time, confirming the absence of implant biodegradation. The volume fraction and mean width of bone remained stable in the implant but increased in the graft specimens, corresponding to graft neocortex formation. It is concluded that implants initially filled in with bone while grafts initially replaced much of their spongiosa and subsequently filled in with bone. Histometry of untreated defects and measurement of mechanical properties are suggested for further study.

Osteogenic protein 1 device increases bone formation and bone graft resorption around cementless implants

“…However, bone formation in the ProOsteon 200 group was signi cantly greater than in the allograft group in zone 2, indicating that ProOsteon 200 is a good osteoconductor (Table 2). ProOsteon is a slow resorbing bone substitute (Shimazaki and Mooney 1985, Holmes et al 1987, el Deeb and Holmes 1989, Martin et al 1993). Accordingly, we found no signi cant resorption of HA granules after 3 weeks (Table 4).…”

Production of tubular porous hydroxyapatite using electrophoretic deposition

“…Porosity is an important factor for the biological fixation of bioceramics to living bone, 5) while the pore size and morphology of the scaffolds affects tissue ingrowth to the implanted biomaterials. 6) Furthermore, porosity plays an important role in the mechanical fixation between biomaterials and hard living tissues.…”

Application of interconnected porous hydroxyapatite ceramic block for onlay block bone grafting in implant treatment: A case report (Review)

“…Hydroxyapatite ceramics (HA) materials have been used as a substitute for bone grafting because the crystalline phase of natural bone is similar to that of HA (16,17), while porous calcium hydroxyapatite ceramics (CHA) materials have been utilized in orthopedic and craniofacial surgery procedures since the 1980s (18). However, few studies have reported cases in which conventional CHA became fully filled by newly formed bone, which may be due to its structure and limited connectivity between pores (19).…”