Management of regional bone bank during declaration of a state of emergency concerning the COVID-19 in Japan.

Bone banks are necessary for providing biological allografts for a series of orthopedic procedures. As nations cope with new realities driven by the 2019 coronavirus disease (COVID-19) pandemic, health-care providers, institutions, and patients share a particular concern about the effect of COVID-19 on organ donation and transplantation. Here, we describe the management of the Kitasato University Bone Bank during the state of emergency declared in response to COVID-19. Living donors received pre-operative screening by PCR, and allograft bone from COVID-19-negative donors was cryopreserved as transplantable tissues. The weekly rate of infection gradually increased from February 2-9 to April 5-11 in the dead donor-derived allograft bone-harvesting region covered by the Bank. It is becoming clear that the virus can be transmitted by asymptomatic patients, and that this route may have facilitated the spread of COVID-19. Therefore, the Bank stopped dead donor donation to consider the safety of medical staff. Three recipients received bone allografts following pre-operative COVID-19 screening by PCR. All patients were asymptomatic after bone allograft. Our experience may provide helpful information for the management of tissue banks.

Allogenic serum improves cold preservation of osteochondral allografts.

BACKGROUND: Although several types of culture medium have been used for preservation of osteochondral allografts, the viability of chondrocytes decreases with increasing storage duration. We previously showed the University of Wisconsin solution is more suitable for graft preservation than culture medium. QUESTIONS/PURPOSES: We determined whether the addition of allogenic serum to University of Wisconsin solution increases chondrocyte survival during prolonged storage of osteochondral allografts. METHODS: Osteochondral tissue samples harvested from the distal femora of rats were preserved in University of Wisconsin solution supplemented with 0%, 1%, 10%, and 50% allogenic serum at 4 °C for 14 days. Cell viability and chondrocyte degenerative changes of the samples then were assessed using a tetrazolium assay and histologic methods. We also evaluated time-dependent changes in cell viability and histologic findings of samples preserved for 7, 14, and 21 days in University of Wisconsin solution supplemented with or without 10% allogenic serum. RESULTS: After 14 days of preservation, osteochondral tissue samples maintained in University of Wisconsin solution containing 10% or greater allogenic serum exhibited the highest cell viability and lowest degenerative changes in chondrocytes. In the evaluation of time-dependent changes, we found the chondrocyte degenerative changes were greater in cartilage preserved in University of Wisconsin solution alone than in University of Wisconsin solution containing 10% allogenic serum after day 7 or later. CONCLUSIONS: Our results suggest the addition of 10% allogenic serum to University of Wisconsin solution enhances viability of osteochondral tissue samples. CLINICAL RELEVANCE: The use of allogenic serum-supplemented University of Wisconsin solution is expected to prolong the duration of osteochondral allograft storage and result in higher-quality grafts.

Repeated freeze-thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons.

Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze-thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze-thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze-thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze-thaw cycles. In patella tendons, the ultimate stress, Young's modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze-thaw cycles. In conclusion, we identified that cells surviving after freeze-thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze-thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity.

Quality assessment for processed and sterilized bone using Raman spectroscopy.

To eliminate the potential for infection, many tissue banks routinely process and terminally sterilize allografts prior to transplantation. A number of techniques, including the use of scanning electron microscopy, bone graft models, and mechanical property tests, are used to evaluate the properties of allograft bone. However, as these methods are time consuming and often destroy the bone sample, the quality assessment of allograft bones are not routinely performed after processing and sterilization procedures. Raman spectroscopy is a non-destructive, rapid analysis technique that requires only small sample volumes and has recently been used to evaluate the mineral content, mineral crystallinity, acid phosphate and carbonate contents, and collagen maturity in human and animal bones. Here, to establish a quality assessment method of allograft bones using Raman spectroscopy, the effect of several common sterilization and preservation procedures on rat femoral bones were investigated. We found that freeze-thawing had no detectable effects on the composition of bone minerals or matrix, although heat treatment and gamma irradiation resulted in altered Raman spectra. Our findings suggest Raman spectroscopy may facilitate the quality control of allograft bone after processing and sterilization procedures.

Long-term antibacterial activity of vancomycin from calcium phosphate cement in vivo.

BACKGROUND: Periprosthetic joint infection is a major complication of total joint arthroplasty, with treatment requiring a two-stage exchange procedure and 6 weeks of systemic antibiotics. However, depending on the infection site, intravenous delivery of antibiotics like vancomycin (VCM) can have poor tissue transferability, thus reducing their therapeutic effect. OBJECTIVE: This study demonstrates the 24-week in vivo release profile and antibacterial activity of VCM from calcium phosphate cement impregnated with VCM (CPC/VCM) and compares them with those from polymethylmethacrylate impregnated with VCM (PMMA/VCM). METHODS: Rats were implanted with the test specimens between the fascia and quadriceps. After implantation for 24 weeks, the test specimens were removed and residual VCM was extracted to calculate the concentration of VCM released into rat tissues. We also examined the antibacterial activity of releasable VCM from the removed test specimens by placing them directly onto the surface of agar. RESULTS: CPC/VCM released greater concentrations of VCM for a longer period of time within the 24 weeks than PMMA/VCM. Moreover, CPC/VCM released 1.4 to 26.1-fold more VCM than PMMA/VCM. Using Staphylococcus aureus, antibacterial activity was logarithmically correlated with VCM concentration across the entire concentration range tested (12.5-800 µg/mL). While the area within which inhibition was observed-the inhibition zone-for both CPC/VCM and PMMA/VCM formed and gradually shrank with time after implantation, that for CPC/VCM was significantly larger than that for PMMA/VCM in each week after implantation. CONCLUSION: CPC/VCM releases greater amounts of VCM with antibacterial activity for longer periods of time than PMMA/VCM, suggesting that CPC is effective for facilitating the release of antibiotics for local action in patients with established postoperative infection.

A new technique for seeding chondrocytes onto solvent-preserved human meniscus using the chemokinetic effect of recombinant human bone morphogenetic protein-2.

Many investigators are currently studying the use of decellularized tissue allografts from human cadavers as scaffolds onto which patients' cells could be seeded, or as carriers for genetically engineered cells to aid cell transplantation. However, it is difficult to seed cells onto very dense regular connective tissue which has few interstitial spaces. Here, we discuss the development of a chemotactic cell seeding technique using solvent-preserved human meniscus. A chemokinetic response to recombinant human bone morphogenetic protein-2 (rhBMP-2) was observed in a monolayer culture of primary chondrocytes derived from femoral epiphyseal cartilage of 2-day-old rats. The rhBMP-2 significantly increased their migration upto 10 ng/ml in a dose-dependent manner. When tested with solvent-preserved human meniscus as a scaffold, which has few interstitial spaces, rhBMP-2 was able to induce chondrocytes to migrate into the meniscus. After a 3-week incubation, newly-formed cartilaginous extracellular matrix was synthesized by migrated chondrocytes throughout the meniscus, down to a depth of 3 mm. These findings demonstrate that rhBMP-2 may be a natural chemokinetic factor in vivo, which induces migration of proliferative chondrocytes into the narrow interfibrous spaces. Our results suggest a potential application of rhBMP-2 for the designed distribution of chondrocytes into a scaffold to be used for tissue engineering.

Therapeutic ultrasound induces periosteal ossification without apparent changes in cartilage.

Low intensity pulsed ultrasound (LIPUS) is an extremely useful noninvasive treatment which halves the duration of fracture healing when the bone is exposed once a day for 20 min. To elucidate the direct reactions of bone and cartilage, dissected rat femora were immobilized in culture dish wells, exposed to LIPUS from a certain angle every day, and the local pattern of ossification was analyzed in relation to the ultrasound. Daily 20-min exposures were started 24 hr after isolation of the femora, and at days 5, 10, and 15, samples were harvested for measurements, morphological, and histochemical analyses. While the gross features of the samples were identical to the untreated controls, extended mineralization of the periosteum was observed with alizarin red staining, antiosteocalcin immunohistochemical staining, and micro-three dimensional computed tomography. Interestingly, the newly deposited mineral was found perpendicular to the ultrasound path, strongly suggesting that LIPUS accelerates periosteal bone formation. Zones of epiphyseal cartilage and hypertrophic and calcified cartilage did not exhibit any differences with and without this exposure. LIPUS also did not influence the secreted proteoglycan components or amounts in the culture medium. The absence of any additional longitudinal growth of the femur demonstrated that LIPUS did not accelerate endochondral bone formation. We conclude that cartilage alone does not directly respond to therapeutic ultrasound, whereas the periosteum does.

Osteoarthritic changes of the patellofemoral joint in STR/OrtCrlj mice are the earliest detectable changes and may be caused by internal tibial torsion.

STR/ort mice develop a naturally occurring osteoarthritis (OA) of the knee joints. However, the evaluation of early OA changes has been difficult due to variability caused by gender, individual differences, and differences between the right and left lower limbs. The objective of this study was to analyze the variability of the early OA changes with age in STR/ort mice and to identify the cause of onset. A total of 115 STR/OrtCrlj mice aged 10-45 weeks were examined. In addition to conventional radiological and histological evaluation of the knee joints, histological sections were used to examine the patellofemoral, femorotibial, and growth plate cartilage under similar conditions. A morphological evaluation of tibiae, including micro-3-dimensional computed tomography, was performed. Radiological evaluation showed OA changes in the joints of mice over 35 weeks old and histological evaluation showed early OA changes in the femorotibial joints of mice over 26 weeks old. However, these changes were not common in all individuals. In contrast, most common and reproducible OA changes were observed in the bilateral patellofemoral joints of all individuals, and even in subjects ranging from 10 to 20 weeks of age. Morphological evaluations also demonstrated an abnormal tibial internal torsion that increased with age and was associated with medial patellar dislocation. In conclusion, the earliest histological OA change was observed in the patellofemoral joint prior to similar observations in the femorotibial joint. Internal tibial torsion may be a cause of OA in the patellofemoral joints, which leads to the development of medial femorotibial OA.

In vitro comparison of elution characteristics of vancomycin from calcium phosphate cement and polymethylmethacrylate.

BACKGROUND: Calcium phosphate cement [CPC (Biopex)] has been used as the drug delivery system of choice for treatment of infected joint replacement because of its good elution efficiency. The influence of CPC polymerization on the bactericidal activity of vancomycin (VCM) impregnated into CPC has not been investigated. We compared VCM concentration, bactericidal activity, and profile of eluates between CPC and polymethylmethacrylate (PMMA; Cemex RX). METHODS: Test specimens consisted of a powder composite of CPC or PMMA, VCM and solvent (10:0.25:3.3 g). Each test specimen was immersed in sterile phosphate-buffered saline. Eluates obtained on days 1, 3, 7, and 14 and weeks 4, 8, and 12 were evaluated by high performance liquid chromatography (HPLC) and by microbiological assay (MBA). RESULTS: The elution level of VCM from CPC/VCM on day 1 was 8.1 fold greater than that from PMMA/VCM. The detection periods of VCM from CPC/VCM and PMMA/VCM were 8 weeks and 14 days, respectively. The values of eluates from CPC/VCM and PMMA/VCM obtained by HPLC were comparable to those obtained by MBA. HPLC chromatogram showed that the elution profiles of VCM from CPC/VCM and PMMA/VCM on day 1 were very close to those of standard solutions. CONCLUSIONS: CPC could release more VCM over a longer period than PMMA. The polymerization of CPC and PMMA did not alter the inhibitory activity of VCM and did not denature VCM.

The effect of cryopreservation or heating on the mechanical properties and histomorphology of rat bone-patellar tendon-bone.

The effects of cryopreservation on tendon allograft have been reported, but remain unclear, particularly the potential effects on mechanical properties and histological changes by ice crystal formation. There are also few studies about effects of heating for sterilization of tendon. We evaluated the effect of cryopreservation or heating on the mechanical properties and histomorphology of rat bone-patellar tendon-bones (BTBs). BTBs were processed by cryopreservation at -80 degrees C for 3 weeks, or heating at 80 degrees C for 10 min. Tensile testing and histomorphological examination were performed. The cryopreservation of tendons showed less influences on their mechanical properties. When cryopreserved BTBs in frozen state were fixed by freeze-substitution method, many spaces were observed in interfibrillar substances. These results suggest that the collagen fibers of cryopreserved tendons were histomorphologically affected by ice crystals. The heating of tendons completely destroyed the collagen fibers of the tendons and is therefore thought to be inappropriate for the sterilization of BTBs.

Cold preservation of rat osteochondral tissues in two types of solid organ preservation solution, culture medium and saline.

We compared Dulbecco's modified Eagle's medium (DMEM), saline, Euro-Collins (EC) solution and University of Wisconsin (UW) solution to determine which was best for cold preservation of rat osteochondral tissues (OCTs). After 7 days' cold preservation, OCTs kept in UW solution had the highest relative viable cell number by the tetrazolium assay and the lowest activity of lactate dehydrogenase released from damaged cells. Histological evaluation revealed chondrocyte deformity, such as shrunken cytoplasm and pyknotic nuclei, particularly in the deeper layer of articular cartilage after preservation in saline and EC solution and predominantly in all layers if preserved in DMEM. In contrast, chondrocyte morphology in all layers of the articular cartilage preserved in UW solution was relatively unchanged and remained similar to fresh OCTs. It is therefore concluded that UW solution is the most suitable for cold preservation of rat OCTs as well as solid organs.

The expense for one implantation of a banked bone allograft from a cadaveric donor and the issues affecting current advanced medical treatment in the Japanese orthopaedic field.

Demand for banked bone allografts is increasing in Japan; however, there are too few bone banks and the bone bank network is not well-established. One reason for this was lack of funding for banks. Bone banks had to bear all material expenses of banked bone allografts themselves because this was not designated a covered expense. In December 2004, the Japanese government started a new "Advanced Medical Treatment" administration system which allowed an approved institution to charge the expense of authorized advanced medical treatments directly to patients. The treatment named "Cryopreserved allogenic bone and ligamentous tissue retrieved from cadaveric donor" was approved as an advanced medical treatment in March 2007. We present the calculation method and the expense per implantation of a banked bone allograft from a cadaveric donor under this treatment and raise issues which affect this advanced medical treatment and remain to be resolved in the Japanese orthopaedic field.

In Vivo Release of Vancomycin from Calcium Phosphate Cement.

Calcium phosphate cement (CPC) has good release efficiency and has therefore been used as a drug delivery system for postoperative infection. The release profile of CPC has mainly been evaluated by in vitro studies, which are carried out by immersing test specimens in a relatively large amount of solvent. However, it remains unclear whether antibiotic-impregnated CPC has sufficient clinical effects and release in vivo. We examined the in vivo release profile of CPC impregnated with vancomycin (VCM) and compared this with that of polymethylmethacrylate (PMMA) cement. To evaluate the release profile in vitro, the test specimens were immersed in 10 mL sterile phosphate-buffered saline per gram of test specimen and incubated at 37°C for 56 days in triplicate. For in vivo experiments, the test specimens were implanted between the fascia and muscle of the femur of rats. Residual VCM was extracted from the removed test specimens to determine the amount of VCM released into rat tissues. CPC released more VCM over a longer duration than PMMA in vitro. Released levels of VCM from CPC/VCM in vivo were 3.4-fold, 5.0-fold, and 8.6-fold greater on days 1, 7, and 28, respectively, than those released on the corresponding days from PMMA/VCM and were drastically greater on day 56 due to inefficient release from PMMA/VCM. The amount of VCM released from CPC and PMMA was much higher than the minimum inhibitory concentration (1.56 µg) and lower than the detection limit, respectively. Our findings suggest that CPC is a suitable material for releasing antibiotics for local action against established postoperative infection.

5. Accelerated Fracture Healing Targeting Periosteal Cells: Possibility of Combined Therapy of Low-Intensity Pulsed Ultrasound (LIPUS), Bone Graft, and Growth Factor (bFGF).

We have studied the mechanism of fracture healing, and the effect of LIPUS, bone graft and growth factor on accelerating fracture healing. We present here the results of our research. To examine callus formation cells in fracture healing, we made marrow GFP chimera mice and a fracture model of marrow mesenchymal stem cell GFP chimera mice. It was demonstrated that periosteal cells were essential for callus formation. We focused on periosteal cells and examined the effect of LIPUS. In an in vitro experiment using a cultured part of the femur, LIPUS promoted ossification of the periosteal tissue. Further, LIPUS accelerated VEGF expression in the experiment using the femoral fracture model of mice. From these results, it was suggested that activation of periosteal cells might play a role in the fracture healing mechanism of LIPUS. Next, we discussed the possibility of combined therapy of LIPUS, bone graft and growth factor. Therapy involving the topical administration of bFGF using a controlled release system and bone graft could promote callus formation. In addition, LIPUS was able to promote membranaceous ossification after the bone graft. It was suggested that combined therapy of LIPUS, bone graft and bFGF could be a new option for treating fractures.

4. The Low-Intensity Pulsed Ultrasound (LIPUS) Mechanism and the Effect of Teriparatide on Fracture Healing.

Low-Intensity Pulsed Ultrasound (LIPUS) provided a mechanical stimulus, and was thought to promote fracture healing by signal transduction through integrin, a cytoskeletal protein. Meanwhile, teriparatide, a drug for osteoporosis treatment, showed efficacy in promoting bone metabolism. This drug also appeared to prevent fractures in patients with serious osteoporosis by improving bone mineral density and bone quality, which in turn resulted from promoting action for bone metabolism. Further, clinical trials and fundamental research reported that teriparatide demonstrated the effect of promoting fracture healing. Mechanical stimulus by LIPUS had a topical effect on fractures; on the other hand, teriparatide (peptide hormone) had both topical and systemic effects. Both LIPUS and teriparatide had the effect of fracture healing, but it was supposed that the characteristics of each effect were different because of the different mechanism of action. Moreover, the combination therapy of LIPUS and teriparatide was expected to produce synergies. We used elderly rats as models for the femoral fracture to examine the effects of LIPUS and teriparatide on promoting fracture healing for treatment delay by aging. We observed the fracture healing process in 40-week-old rats as an elderly model using simple radiographs, and recognized a delay in fracture healing compared with that of 8-week-old rats. As discussed in histomorphology, it was demonstrated that the period of endochondral ossification, from chondrogenesis to teleost cross-linked callus, was prolonged and the fracture healing process was delayed by aging. Next, we treated the elderly fracture models with LIPUS for 20 minutes a day from the first day after the fracture, and compared them with non-treated models. The bone unions of the treated models were observed earlier than those of non-treated models in the simple radiographs. LIPUS shortened the period of endochondral ossification. Further, we gave the elderly fracture models teriparatide subcutaneously 5 µg/kg three times a week from the first day after the fracture. Bone unions of the treated models were observed earlier than those of non-treated models in simple radiographs as well. In micro CT analysis, it was demonstrated that lamellar bone transforming and bone remodeling of the trabecular structure of external callus were especially accelerated. The results of these trials showed that both LIPUS and teriparatide demonstrated the effect of promoting fracture healing, and each had unique characteristics.

12. Influence of Wound Dressing on the Fracture Healing Effect of Low-Intensity Pulsed Ultrasound (LIPUS).

OBJECTIVE: We have conducted a basic study on the influences on ultrasonic properties when LIPUS is applied through wound dressing. According to the results of ex vivo experiments conducted to date, LIPUS showed ultrasonic properties such as transmittance, coefficient of transmission, and a non-uniformity ratio through film wound dressing better than other wound dressing, and it was considered that LIPUS's effect for fracture healing was not influenced by film wound dressing. Then, we discussed the influence on the effect of LIPUS through film wound dressing. METHODS: Thirty male 8-week-old Sprague-Dawley rats were used for the trial. After creating close transverse femoral fractures on the right legs of these 30 rats, they were divided into 3 groups of 10; LIPUS through wound dressing (Group A), LIPUS without wound dressing (Group B), and No LIPUS treatment (Group C). OPSITE Wound, which was thought to have the least influence on ultrasound properties, was used for this trial. Group A and B received LIPUS for 20 minutes a day from the first day after the fractures. LIPUS was generated from Teijin Pharma's device for a basic experiment. When treating Group A, the wound dressing was pasted on the ultrasound terminal in order to apply LIPUS through the dressing. We assessed the time-oriented morphological change of each group in anesthetized condition using simple radiographs on the 8th, 16th, and 24th day after the fractures. RESULTS: Six rats in Group A, 2 in Group B, and 1 in Group C died in anesthesia, and we discussed the remaining 4 rats in Group A, 8 in Group B, and 9 in Group C. We defined more than one teleost callus bridging as bone-union. We also counted a bone remodeling when we recognized the absorption of existing cortical bone and the transformation of new bone to cortical bone in simple radiographs. As a result, compared with Group C, we recognized that both bone union and remodeling accelerated remarkably in Group B, but not in Group A. DISCUSSION: It suggested that LIPUS through wound dressing had negative influences on both period shorting of fracture healing and bone remodeling. When LIPUS was conducted through film wound dressing, transmittance and coefficient of transmission were unchanged; however, the non-uniformity ratio changed slightly. The non-uniformity ratio of the ultrasound transducer had a significant influence on the effect of LIPUS on fracture healing.

Spontaneous differentiation of mesenchymal stem cells obtained from fetal rat circulation.

Mesenchymal stem cells (MSCs) are thought to be multipotential, capable of differentiating into multiple lineages. We attempted to characterize rat cells derived from fetal circulating blood (FCBCs) that displayed a fibroblastic morphology and differentiated into osteoblastic and chondrocytic lineages. Notably, they differentiated into a chondrocyte-specific phenotype on plastic culture dishes in medium supplemented only with 10% fetal bovine serum (FBS) without the use of a three-dimensional culture substrate. Bone marrow-derived cells did not convey such phenotypic expression under the same conditions. The characteristic features of these cells were analyzed by reverse transcription polymerase chain reaction, immunohistological and von Kossa staining, and by immuno-dot blotting. In one population, expression of collagen types II and X was detected in differentiated cells at the same levels as observed in chondrocytes derived from rat rib cartilage. In another population, parathyroid hormone receptor, alkaline phosphatase, and osteocalcin were also expressed at levels almost equal to those observed in long bone-derived osteoblasts. After 3 weeks in culture, extensively condensed cell masses, stained with anti-type II collagen antibody, could be distinguished histologically from small, multilayered, von Kossa-positive nodules, which stained with anti-osteocalcin, but not with anti-type II collagen antibody. In addition, the FCBCs differentiated into adipogenic cells in the presence of methyl-isobutyl xanthine, dexamethasone, insulin, and indomethacin. These cells expressed PPARgamma2 mRNA and accumulated lipid vesicles detectable by Oil red-O staining. Our findings suggest that FCBCs have the potential to readily differentiate into multiple lineages and that they are distinct from mesenchymal stem cells derived from bone marrow or circulating blood from more mature and adults in their spontaneous differentiation in the absence of specific factors such as transforming growth factor-beta (TGF-beta) or dexamethasone, or a three-dimensional culture environment.

Expression of parathyroid hormone-related peptide and insulin-like growth factor I during rat fracture healing.

Parathyroid hormone-related peptide (PTHrP) and insulin-like growth factor I (IGF-I) are both involved in the regulation of bone and cartilage metabolisms and their interaction has been reported in osteoblasts. To investigate the interaction of PTHrP and IGF-I during fracture healing, the expression of mRNA for PTHrP and IGF-I, and receptors for PTH/PTHrP and IGF were examined during rat femoral fracture healing using an in situ hybridization method and an immunohistochemistry method, respectively. During intramembranous ossification, PTHrP mRNA, IGF-I mRNA and IGF receptors were detected in preosteoblasts, differentiated osteoblasts and osteocytes in the newly formed trabecular bone. PTH/PTHrP receptors were markedly detected in osteoblasts and osteocytes, but only barely so in preosteoblasts. During cartilaginous callus formation, PTHrP mRNA was expressed by mesenchymal cells and proliferating chondrocytes. PTH/PTHrP receptors were detected in proliferating chondrocytes and early hypertrophic chondrocytes. IGF-I mRNA and IGF receptor were co-expressed by mesenchymal cells, proliferating chondrocytes, and early hypertrophic chondrocytes. At the endochondral ossification front, osteoblasts were positive for PTHrP and IGF-I mRNA as well as their receptors. These results suggest that IGF-I is involved in cell proliferation or differentiation in mesenchymal cells, periosteal cells, osteoblasts and chondrocytes in an autocrine and/or paracrine fashion. Furthermore, PTHrP may be involved in primary callus formation presumably co-operating with IGF-I in osteoblasts and osteocytes, and by regulating chondrocyte differentiation in endochondral ossification.

Comparison between the shape of resected femoral sections and femoral prostheses used in total knee arthroplasty in Japanese patients: simulation using three-dimensional computed tomography.

Simulation of the femoral cut for total knee arthroplasty was performed in 44 knees using three-dimensional computed tomography. The three-dimensional images were measured, and the shape of the femur was compared to the provided femoral prosthesis. The ratio between the medial-lateral and anteroposterior dimensions of the three-dimensional images did not always match the prosthesis. The widths of the medial condyles of the three-dimensional images tended to be larger than those of the prosthesis. The lengths of the lateral posterior condyles of the three-dimensional images tended to be shorter than those of the prosthesis. These results suggest that a new prosthesis should be designed to achieve a better anatomical fit.