Bone formation and resorption in patients after implantation of β‐tricalcium phosphate blocks with 60% and 75% porosity in opening‐wedge high tibial osteotomy

Abstract

Most of the implanted porous beta-tricalcium phosphate (beta-TCP) can be resorbed. However, beta-TCP block with 75% porosity is inadequate for weight-bearing sites until bone incorporation occurs. Thus, the authors have recently developed beta-TCP block with 60% porosity, which is approximately sevenfold greater in terms of compressive strength than that of beta-TCP with 75% porosity. The authors investigated bone formation and resorption of beta-TCP after implantation in patients of beta-TCP blocks with two different porosities. From May 2003 to November 2004, medial opening high tibial osteotomy was performed in 25 patients with a mean age of 66 years. The opened defect was fixed with a Puddu plate. Then 6-8 cm(3) of beta-TCP block with 75% porosity was used to fill the cancellous bone defect, except on the medial side where 2.83-3.18 cm(3) of wedge-shaped beta-TCP block with 60% porosity was implanted. At least 2 years after surgery, the 25 patients had no correction loss, and bone formation was noted in all cases. Complete or nearly complete resorption of beta-TCP with 60 and 75% porosity was obtained within 3.5 years. Thirteen biopsy samples obtained from the 60% porosity implantation sites showed good lamellar bone formation, and the percentage of beta-TCP remaining relative to the newly formed bone plus beta-TCP ranged from 0.3 to 14.5%, with a mean of 6.7%. The authors suspect that mechanical stress loading to the medial side of the tibia facilitated bone formation and resorption of beta-TCP with 60% porosity.

An Injectable Complex of β-tricalcium Phosphate Granules, Hyaluronate, and rhFGF-2 on Repair of Long-bone Fractures with Large Fragments

“…It has been reported that β-TCP has excellent osteoconduction and resorbability when filling a bone defect [1][2][3][4][5][6][7][8][9]. With regard to shape, both block and granular forms of β-TCP have been available; however, *Address correspondence to these authors at the Department of Orthopaedic Surgery, NHO Utsunomiya National Hospital, 2160 Shimo-Okamoto, Utsunomiya city, Tochigi, 329-1193 Japan; Tel: +81 28 673 2111; Fax: +81 28 673 9117; E-mail: tanakat@e-utunomiya.hosp.go.jp some cases have presented difficulty in filling irregularly shaped bone defects.…”

Technologies Applied to Stimulate Bone Regeneration

“…The pore density can range between 40% and 60%, with Ca:P stequiometric ratio similar to spongy bone, imitating it (Gautier et al, 1998;Tanaka et al, 2008;Porter et al, 2009). Osteoconduction with calcium phosphate, often used in beta conformation, as beta-tricalcium phosphate (-TCP, CA3(PO4)2), results in resorption of the biomaterial and osseointegration of the treated region in approximately 12 weeks.…”

“…The persistence of the biomaterial favors the treatment of cavities resulting from bone resection, filling of osteotomy regions, defects of critical size of the bone (Gaasbeek et al, 2005;Tanaka et al, 2008) The physical properties of -TCP favor its association with liquids such as blood and bone marrow aspirate. In an experimental study with dogs, Bruder and collaborators demonstrated bone formation and the refinement of the bioceramic in association with mesenchymal cells obtained from bone marrow aspirate .…”

Ensuring defined porosity and pore size using ammonium hydrogen carbonate as porosification agent for calcium phosphate scaffolds

“…One of the most compre hensively investigated degradable calcium phosphates is βtricalcium phosphate (βTCP) which is proven to be a biocompatible, biodegradable and osteoconductive mate rial [4][5][6]. Besides the choice of the bone replacement mate rial, specific parameters such as, the percentage of porosity [7], the pore size [8] and the interconnectivity [9] are crucial for a complete in-vivo degradation of the bone replacement material. Most studies suggest a pore diameter of 100-1220 µm to ensure adequate degradation, remodelling and vas cularisation [8,[10][11][12][13].…”

“…Most studies suggest a pore diameter of 100-1220 µm to ensure adequate degradation, remodelling and vas cularisation [8,[10][11][12][13]. Furthermore, the volume percentage of the total porosity should be higher than 60% [7]. Besides the requirement for a specific macroporosity of the ceramic scaffold, a certain percentage of microporosity is important for osteogenesis and the anchoring of the implant to sur rounding bone tissue [14].…”