Unidirectional Porous Β-tricalcium Phosphate Research Articles

Use of Unidirectional Porous β-Tricalcium Phosphate in the Tibial Tunnel for Anterior Cruciate Ligament Reconstruction: A Case Series.

Bone defects in the tibial tunnel for anterior cruciate ligament (ACL) reconstruction can cause adverse events. The unidirectional porous tricalcium β-phosphate (UDPTCP) has the potential to be used as a filling substitute for bone defects. In this case series, we present the first nine cases in which UDPTCP was used as a bone substitute in the tibial tunnel during ACL reconstruction. The patients comprised six males and three females, with an average age of 32 years (range: 16-50 years). A cylindrical UDPTCP measuring 10 x 20 mm was molded to fit the tibial tunneland then implanted. At the one-year postoperative follow-up, none of the patients demonstrated any complications, and bone remodeling was observed on radiographs. Therefore, UDPTCP may provide a safe and reliable filling substitute for the tibial tunnel in ACL reconstruction.

Open reduction and Kirschner wire fixation method using a cylindrical block of unidirectional porous β-tricalcium phosphate for tongue-shaped calcaneal fracture: Report of three cases

The artificial bone grafts are performed on the defect after reduction of the calcaneal fracture. Generally, it is an artificial bone graft with an implant, and there are a few reports of an artificial bone graft without an implant. We report three cases (42-year-old male, 67-year-old male, 21-year-old female) of a tongue-shaped calcaneal fracture treated using a cylindrical unidirectional porous β-tricalcium phosphate artificial bone (Affinos®, Kurare co Ltd., Hyougo, Japan) to surgically repair bone defects after reduction. The bone defect is often observed when fracture is reduced in calcaneal fracture. There were significant bone defects, which were then fixed using Affinos® (forming a cylindrical shape block; diameter 10 mm x height 20 mm) to support the bone fragment, an artificial β-tricalcium phosphate bone with a porosity of 57 % (pore size 25–300 μm), characterized by a novel unidirectional porous structure. Postoperative early rehabilitation started with partial load from 5 weeks after surgery and was full weight bearing at 9 weeks after surgery. There was no correction loss and good bone fusion was obtained. By 12 months postoperatively, patients were able to be walking without pain and absorption and bone fusion around the artificial bone were observed maintaining the morphology immediately after reduction. The result was a good clinical result of one excellent (92 points) and two good (81 and 84 points) 1 year after surgery in the postoperative AOFAS Ankle-Hindfoot Scale. Affinos® has a frost-like structure, which endows it with good tissue invasive properties because of the capillary effect. Moreover, it has excellent osteoconduction capability. In these 3 cases, Affinos® showed good strength, affinity, absorption, and bone substitution in a tongue-shaped calcaneal fracture. Further prospective studies are required to confirm our findings.

Efficacy of platelet-rich plasma impregnation for unidirectional porous β-tricalcium phosphate in lateral lumbar interbody fusion: study protocol for a prospective controlled trial

BackgroundThe use of platelet-rich plasma has been increasing in spinal fusion surgery. However, the efficacy of platelet-rich plasma in lateral lumbar interbody fusion is unclear. In Japan, Affinos,® (Kuraray Co., Tokyo, Japan), a β-tricalcium phosphate artificial bone, has been increasingly used for spinal fusion. The purpose of this trial is to demonstrate whether Affinos® impregnated with platelet-rich plasma can achieve a higher fusion rate and better clinical outcomes than Affinos® alone.MethodsThe current study is a prospective randomized controlled trial. This trial will include consecutive patients scheduled for lateral lumbar interbody fusion. An intervertebral cage for lateral lumbar interbody fusion has two spaces for bone grafts. As a consequence, two bone grafts are inserted at each intervertebral level. In this study, an artificial bone with platelet-rich plasma will be inserted into one space, and an artificial bone without platelet-rich plasma will be inserted into the other space. We will compare the fusion rates between the bone grafts with and without platelet-rich plasma. Our primary endpoint will be the interbody fusion rate at 1 year after surgery.DiscussionThis trial will verify the efficacy of platelet-rich plasma with Affinos® for bony fusion in lateral lumbar interbody fusion. It will also provide substantial evidence for the effectiveness and safety of platelet-rich plasma in spinal fusion surgery.Trial registrationJapan Registry of Clinical Trials (jRCT) jRCTb032200199. First registered on 13 November 2020. jRCT is approved as a member of the Primary Registry Network of WHO ICTRP.

Characterization of bone remodeling of two different porous types of β-tricalcium phosphates: a quantitative site-by-site analysis using computed tomography.

This study compared the process of bone remodeling using spherical porous β-tricalcium phosphate (SPTCP) and unidirectional porous β-tricalcium phosphate (UDPTCP) by quantitative computed tomography (CT) analysis. We retrospectively analyzed the data of 16 patients (4 men, 12 women; age, 43-78years) who underwent medial opening wedge high tibial osteotomy (MOWHTO) and were followed up for 1year postoperatively. Nine patients used SPTCP spacers and seven patients used UDPTCP spacers. CT was performed at 1week, 6months, and 1year postoperatively. CT attenuation values were measured at three sites on the axial slice and sagittal slice, i.e., the superior, center, and inferior sites and the lateral, center, and medial sites for UDPTCP and SPTCP, respectively. CT attenuation values were lower for UDPTCP than for SPTCP in all sites at 6months and 1year postoperatively (p < 0.05). CT attenuation values decreased in the superior and inferior sites for UDPTCP (p < 0.05), and CT attenuation values decreased in the lateral site for both SPTCP and UDPTCP (p < 0.05). The process of bone remodeling differed between the two over a short-term follow-up of 1year postoperatively.

Use of unidirectional and spherical porous β-tricalcium phosphate in opening-wedge high tibial osteotomy: a case series.

Introduction: Unidirectional porous β-tricalcium phosphate (UDPTCP) consists of a novel porous artificial bone that is structurally different from conventional artificial bone comprised of spherical porous β-tricalcium phosphate (SPTCP).Case presentation: We present our first four clinical cases of opening-wedge high tibial osteotomy (OWHTO) using UDPTCP and SPTCP together. The patients’ mean age was 54.5 ± 5.9 years, and the mean observation period was 20.8 ± 2.8 months. In OWHTO, two wedge shaped pieces of UDPTCP and SPTCP were cut to fit the gap and implanted parallel to each other in the anterior and posterior parts, respectively. We evaluated the correction loss and bone remodeling for UDPTCP and SPTCP over time using radiography and computed tomography, and evaluated the clinical outcomes.Conclusion: There was no correction loss reported in any case, and early bone remodeling was observed with UDPTCP. All patients achieved satisfactory clinical results with no adverse events.

A Novel Unidirectional Porous β-tricalcium Phosphate Bone Substitute in Orthopedic Surgery: A Technical Note and Case Illustrations.

Bone grafting is frequently performed in orthopedic surgeries. Artificial bone is a common grafting material. We have developed an absorbable material for bone regeneration with a unique structure: unidirectional porous β-tricalcium phosphate (AffinosⓇ; Kuraray Co., Ltd., Tokyo, Japan). The most distinctive feature of this material is the ease with which blood can rapidly reach its depths by capillary action due to the unidirectional porous structure. It is also characterized by the presence of micropores, which are known to be beneficial for osteoconductivity both on the surface and inside the material. Favorable artificial bone absorption and regeneration with natural bone were observed in cases of clinical bone graft applications in the spine, extremities, benign bone tumor, trauma, and donor sites. Affinos is useful as a novel absorbable material for bone regeneration in various orthopedic surgeries.

Unidirectional Porous β-Tricalcium Phosphate: A New Bone Filling Substitute for Treatment of Distal Radius Fracture in the Elderly Population.

Background: A new beta-tricalcium phosphate with unidirectional pore structure (UDPTCP), Affinos® (Kurray, Okayama, Japan), has been in clinical use since 2015. To date, there have been only a few clinical studies using this material. We report here the first clinical study for distal radial fracture in the elderly population treated with UDPTCP. Methods: Consecutive patients aged 65 years or older with dorsally displaced unstable fracture of the distal radius (n = 36) were treated operatively in our department. Following reduction of the fracture site, a 7 mm size cube of UDPTCP was placed in the gap of the bony defect and the fracture stabilized with mono-axial or poly-axial type locking plates and screws. Remodeling of the UDPTCP was evaluated by plain radiograph and clinical outcomes were also assessed. Results: UDPTCP was significantly resorbed at 2 months after surgery, both at the center and periphery of the material. Complications were only observed in the post-operative period. Significant correction loss of radial alignment was seen in patients stabilized with poly-axial locking plate. The clinical outcome in all cases was excellent. Conclusions: Block UDPTCP is a safe and convenient material for the treatment of distal radius fracture and is replaced within a suitable time period after grafting into the fracture site. UDPTCP and stable internal fixation is therefore a reliable strategy for restoring and preserving anatomical position, especially in the elderly population.

A unidirectional porous beta-tricalcium phosphate promotes angiogenesis in a vascularized pedicle rat model

BackgroundVarious types of artificial bone have been developed as alternatives to autologous bone grafts. In designing artificial bone, a porous structure is essential for the infiltration of blood and cells, which promotes angiogenesis within the bone matrix and ultimately ossification. However, it remains unclear what kind of pore system best promotes ossification. Here, we investigated angiogenesis in three different types of porous β-tricalcium phosphate (β-TCP) in a vascularized pedicle rat model. MethodsThree types of porous β-TCP—β-TCP60 (60% porosity), β-TCP75 (75% porosity), and unidirectional porous β-tricalcium phosphate (UDPTCP; 57% porosity)—were examined. A cylindrical piece of artificial bone was implanted beneath the superficial inferior epigastric (SIE) vessels in the groin of rats and angiogenesis was allowed to occur. Two weeks after surgery, India ink or lectin was systemically injected to detect newly formed blood vessels originating from the SIE vessels. Immunohistochemistry for von Willebrand factor, α-smooth muscle actin, or type IV collagen was performed to clarify the structural features of the newly formed capillaries within the vascularized UDPTCP. ResultsThe vascularity of the UDPTCP was superior to that of β-TCP60 and β-TCP75. The UDPTCP pore structure was completely filled with capillaries at 3 weeks after implantation. Immunohistochemistry showed that the walls of the capillaries contained endothelial cells, pericytes, and basement membrane originating from the SIE vessels, and that the cells proliferated and the basement membrane formed simultaneously as the newly formed capillaries extended through the unidirectional pore structure of the UDPTCP. ConclusionsUDPTCP had greater angiogenic potential than β-TCP60 and β-TCP75 in a vascularized pedicle rat model. Vascularized UDPTCP grafts may be an alternative to vascularized autologous bone grafts.

A novel unidirectional porous β-tricalcium phosphate grafting for vertebral fracture in the elderly: preliminary case series.

Objective: To treat vertebral fractures with posterior wall injury in the elderly, vertebral bone grafting is generally performed through a posterior transpedicular approach, combined with pedicle screw fixation. An autologous bone is ideal to treat this disorder. However, harvesting autologous bones from the elderly with osteoporosis is limited by the amount and quality of available autologous bone. Thus, we developed a bone-grafting substitute. The newly developed unidirectional porous β-tricalcium phosphate, with a porosity of 57% (UDPTCP; Affinos®, Kuraray Co., Ltd., Tokyo, Japan), is used in the bone-grafting procedure. This is the first report of UDPTCP used as an artificial bone graft in patients with an acute vertebral burst fracture.Materials and Methods: UDPTCP (mean: 4.2 g) was implanted through the pedicle, and posterior instrumentation was achieved with pedicle screws in five elderly patients. Resorption of UDPTCP and substitution with the autologous bone were evaluated on computed tomography (CT) and plain X-ray performed immediately and at 3, 6, and 12 months after the operation.Results: In case 1, the pedicle screws did not loosen, and UDPTCP was completely resorbed and replaced with the autologous bone at 3 postoperative months. In the other four cases, although the pedicle screws or the caudal part loosened because of osteoporosis, resorption of UDPTCP was observed at 3 postoperative months. At 6 postoperative months, progressive substitution with the autologous bone was confirmed, and at 12 postoperative months, formation of the good autologous bone was confirmed.Conclusion: This preliminary case series demonstrated that the newly developed UDPTCP shows good clinical potential as a bone-graft substitute for acute vertebral burst fractures in the elderly, including patients with osteoporosis.

The Balance between Bone Formation and Material Resorption in Unidirectional Porous β-Tricalcium Phosphate Implanted in a Rabbit Tibia

We examined the balance between bone formation and material resorption in β-tricalcium phosphate, with unidirectional pores (porosity of 57%) and micropore structure. Using an animal bone defect model, rapid bone formation reached to the center of the material, while the material remained at the same period. Histomorphometric analysis showed that the sum total area of formed bone and material gradually increased with time throughout the experiment. These results indicate that the balance between bone formation and material resorption in this material is satisfactory.

Unidirectional Porous β-Tricalcium Phosphate Bone Substitute: Examination of Balance between New Bone Formation and Absorption

In the present study, we have newly developed an artificial bone substitute, which is unidirectional porous β-tricalcium phosphate (UDPTCP). The objective of this study was to examine the effects of high and low porosity substitutes on the balance between new bone formation and β-TCP absorption. Materials and MethodsSix male Japanese white rabbits (weight 3.1–3.5 kg, approximately 18– 21 weeks old) were used for this study. Intra-venous injection of pent barbiturate was administered and the both medial and lateral femoral condyle were exposed. A hole of 5 mm diameter was drilled to a depth of 12 mm in the metaphysis, perpendicular to the long axis of the femur. (Figure 1) Figure 1. Operation procedureIn the next step, a cylindrical UDPTCP test piece measuring 4.8 × 11 mm was implanted in the holes. Within the bone substitute, unidirectional pores ranging from 100 to 300 μm in diameter were made. This unique architecture fostered transmission of fluids and cells into the piece. In this case, the test piece was implanted into the bone perpendicular to the long axis of the femur, and the orientation of uni-directional pore was parallel to the long axis of femur. We prepared two different test pieces having low (69%) and high (74%) porosities. Half of the animals were sacrificed at 3 weeks after the operation and the remaining half at 6 weeks. After removal of the femoral condyle, the specimen was fixed in formalin and demineralized. Specimens were obtained from the central axis of the cylindrical piece as well as from the lateral or medial surfaces at a distance of 4 mm from midline. The histological samples were prepared for H&amp;E and TRAP staining. Results and Discussion At 3 weeks interval, woven bone, which was formed along the wall of the substitute, could be observed by H&amp;E staining in both low and high porosity substitutes (Figure 2a, 2b). In addition, there were osteoblast-like cells lining the newly formed bone surface with extensive capillary formation (Figure 3). At 6 weeks, the β-TCP walls had thinned and bone had matured in both the groups (Figure 4a, 4b). However, in the high-porosity group, β-TCP absorption tended to be more prominent (Figure 4). In addition, it was observed that at the center of the piece, β-TCP absorption was more prominent than that in the 4 mm-area obtained from the lateral or medial surfaces. At 3 and 6 weeks interval, activities of osteoclast-like multinuclear cells were seen on the surface of the pore wall as observed by TRAP staining. Figure 2a. Low porosity (69%) Figure 2b. High porosity (74%) Fig.2a and Fig.2b H&amp;E staining (×12.5) after 3 weeks (center of the specimen)Figure 3. Formation of woven bone with osteoblast-like cells lining the low porosity specimen at 3 weeks. (H&amp;E staining ×400) Figure 4a. Low porosity Figure 4b. High porosityFig.4a and Fig. 4b H&amp;E staining at 6 weeks after implantation. In high porosity, dense-pink staining areas are located at peripheral in the field.Figure 5. TRAP-positive multinuclear cells (black arrow) were seen on the wall and in the capillaries.Conclusions The UDPTCP implanted in the medullar canal of the femur was absorbed by multinuclear cells and quickly replaced by the newly formed bone. Our results are consistent with those of other studies using porous β-TCP [1]. In our preparation, porosity had certain effects on the balance between bone formation and β-TCP absorption. Because of the unique architecture of unidirectional pores within the β-TCP specimen as well as easy formation of capillary network and access to osteoclasts may have accelerated absorption of the substitute. UDPTCP is very promising scaffolding material for bone regeneration. However, optimization of the porosity of UDPTCP in accordance with its application site is necessary before its clinical use. Reference[1] Naoki Kondo, Akira Ogose, Kunihiko Tokunaga, Tomoyuki Ito, Katsumitsu Arai, Naoko Kudo, Hikaru Inoue, Hiroyuki Irie, Naoto Endo: Bone formation and resorption of highly purified β-tricalcium phosphate in the rat femoral condyle. Biomaterials 26: 5600-5608, October 2005.