Sadao Morita

Performance of adhesive bone cement containing hydroxyapatite particles.

A new acrylic bone cement which can adhere to both bone and prostheses was developed based on a methyl methacrylate (MMA) monomer containing 4-methacryloyloxyethyl trimellitate anhydride (4-META) as adhesion promoting agent. Moreover, hydroxyapatite (HA) particles were introduced into the 4-META cement as a bone compatible filler. The mechanical strengths of an acrylic bone cement without 4-META decreased drastically with an increase in the percentage of HA particles in the cement. However, the mechanical strengths of the HA-containing 4-META cement did not change in the same way as that of the 4-META cement without HA due to adhesion between the cement HA particles and matrix. The HA particles did not affect the adhesion of the 4-META cement to bone and metals. Implantation of the 4-META cement and the HA-containing 4-META cement in animals demonstrated that these cements did not disturb bone ingrowth and the new bone was able to contact the cement directly. The 4-META cements, with and without HA particles, could adhere to bone in vivo.

Three-dimensional motion of the upper extremity joints during various activities of daily living.

Highly reliable information on the range of motion (ROM) required to perform activities of daily living (ADL) is important to allow rehabilitation professionals to make appropriate clinical judgments of patients with limited ROM of the upper extremity joints. There are, however, no data available that take full account of corrections for gimbal-lock and soft tissue artifacts, which affect estimation errors for joint angles. We used an electromagnetic three-dimensional tracking system (FASTRAK) to measure the three-dimensional ROM of the upper extremity joints of healthy adults (N=20, age range 18-34) during 16 ADL movement tasks. The ROM required for the performance of each movement was shown in terms of the joint angle at the completion of the task, using a new definition of joint angle and regression analysis to compensate for estimation errors. The results of this study may be useful in setting goals for the treatment of upper extremity joint function.

Antagonism between apoptotic (Bax/Bcl-2) and anti-apoptotic (IAP) signals in human osteoblastic cells under vector-averaged gravity condition.

Abstract: A functional disorder associated with weightlessness is well documented in osteoblasts. The apototic features of this disorder are poorly understood. Harmful stress induces apoptosis in cells via mitochondria and/or Fas. The Bax triggers cytochrome c release from mitochondria, which can be blocked by the Bcl‐2. Released cytochrome c then activates the initiator caspase, caspase‐9, which can be blocked by the anti‐apototic (IAP) family of molecules. The effector caspase, caspase‐3, finally exerts DNA fragmentation. We conducted this study to examine the apoptotic effects of vector‐averaged gravity on normal human osteoblastic cells. Cell culture flasks were incubated on the clinostat, which generated vector‐averaged gravity condition (simulated microgravity) for 12, 24, 48, and 96 hours. Upon termination of clinostat cultures, the cell number and cell viability were assessed. DNA fragmentation was analyzed on the agarose‐gel electrophoresis. The mRNA levels for Bax, Bcl‐2, XIAP, and caspase‐3 genes were analyzed by semi‐quantitative RT‐PCR. Twenty‐four hours after starting clinostat rotation, the ratios of Bax/Bcl‐2 mRNA levels (indicator of apoptosis) were significantly increased to 136% of the 1G static controls. However, the XIAP mRNA levels (anti‐apoptotic molecule) were increased concomitantly to 138% of the 1G static controls. Thus, cell proliferation or cell viability was not affected by vector‐averaged gravity. DNA fragmentation was not observed in clinostat group as well as in control group. Finally, the caspase‐3 mRNA levels were not affected by vector‐averaged gravity. Simulated microgravity might modulate some apoptotic signals upstream the mitochondrial pathway.

Microgravity Signal Ensnarls Cell Adhesion, Cytoskeleton, and Matrix Proteins of Rat Osteoblasts

Abstract:  Rat osteoblasts were cultured for 4 or 5 days aboard the Space Shuttle and solubilized during spaceflight. Post‐flight analyses by quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) determined the relative mRNA levels of matrix proteins, adhesion molecules, and cytoskeletal proteins including osteopontin (OP), osteonectin (ON), CD44, α‐tubulin, actin, vimentin, fibronectin (FN), and β1‐integrin. The mRNA levels of OP and α‐tubulin in the flight cultures were decreased by 30% and 50% on day 4 and day 5 of flight, as compared to the ground controls. In contrast, the CD44 mRNA levels in the flight cultures increased by 280% and 570% of the ground controls on day 4 and day 5. The mRNA levels of ON and FN in the flight cultures were slightly increased as compared to ground controls. The mRNA levels of actin, vimentin, or β1‐integrin did not change in spaceflight conditions. The matrix proteins, adhesion molecules, and cytoskeletal proteins may form dynamic network complexity with signaling molecules as an adaptive response to perturbation of mechanical stress under microgravity.

Fracture of a ceramic acetabular insert after ceramic-on-ceramic THA: A case report

No Abstract available.

Sirt6 regulates postnatal growth plate differentiation and proliferation via Ihh signaling

Sirtuin 6 (Sirt6) is a mammalian homologue of NAD+-dependent histone deacetylase Sir2. Although Sirt6−/− mice exhibit growth retardation, the role of Sirt6 in cartilage metabolism is unclear. The aim of this study was to investigate the Sirt6 signaling pathway in cartilage metabolism. Immunohistological evaluation of the tibial growth plate in Sirt6−/− mice exhibited impaired proliferation and differentiation of chondrocytes, reduced expression of Indian hedgehog (Ihh), and a senescent phenotype. When Sirt6 was knocked down in chondrocytes in vitro, expression of Ihh and its downstream genes were reduced. Impaired differentiation by Sirt6 silencing was completely rescued by administration of a Hh signal agonist. When sirtuins were activated, chondrocyte differentiation was enhanced together with activation of Ihh signal, and these effects were abrogated by Sirt6 silencing. ChIP assay revealed the affinity of ATF4 to the Ihh promoter was markedly decreased by Sirt6 knockdown. These data indicate Sirt6 directly controls proliferation and differentiation of chondrocytes.

Nonsurgical treatment of congenital clubfoot with manipulation, cast, and modified denis Browne splint

Between 1974 and 1988, 113 congenital clubfeet in 76 children were consecutively treated by using a modified Denis Browne splint with an aluminum crossbar between a pair of plastic shoe inserts after a few manipulations and a corrective cast. Splintage was followed by surgery in 41 (36%) feet. Sixty-nine feet that did not undergo surgery were evaluated after an average follow-up period of 12 years. Sixty-six (95%) feet were excellent or good, according to the McKay rating system. The success rate of this treatment was 60% when the 41 feet receiving surgery and the three feet with fair or poor outcome were evaluated as failures. The success rate was 42% in severely deformed feet, 70% in moderately deformed feet, and 100% in mildly deformed feet. This treatment was effective for congenital clubfoot with mild or moderate deformity and was sometimes effective for severe deformity.

Factors which affect the progression of osteoarthritis after rotational acetabular osteotomy

We have investigated the factors which affect the progression of osteoarthritis after rotational acetabular osteotomy (RAO). Between 1984 and 1998, we treated 60 dysplastic hips by RAO. The mean age at surgery was 31.6 years (13 to 51) and the mean period of follow-up was 4.6 years (2 to 9.5). The thickness of the articular cartilage on the weight-bearing area, pre- and postoperative acetabular cover, and the sphericity of the femoral head were used for radiological assessment. The osteoarthritis did not progress in 39 hips. Significant factors which affected the radiological grade included sphericity of the femoral head and the postoperative acetabular cover. The surgical approach and preoperative acetabular cover did not affect the progression of osteoarthritis. Patients were divided into two groups according to the surgical approach used, either conventional (23 hips) or modified (37 hips). Significant factors included the postoperative acetabular cover in the modified approach, and the sphericity of the femoral head in the conventional approach. It is critical that the postoperative cover is sufficient, especially when RAO is carried out using our modified technique.

Anterior transfer of the toe flexors for equinovarus deformity due to hemiplegia

We report the results of transfer of the long toe flexors and lengthening of the calcaneal tendon in 33 patients with equinovarus deformity requiring orthoses after a stroke. Review of 29 patients more than two years after surgery showed that 21 were able to walk without an orthosis. Equinovarus deformity had recurred in six patients and hammer toe in 11, but walking ability without bracing was still better in seven of these. Results are improved by the release of the short toe flexors.

Prevention of pulmonary embolism by a foot sole pump

We carried out a prospective, randomised study of 62 patients to determine the efficacy of a foot sole pump (the A-V Impulse System) for the prevention of pulmonary embolism (PE) after hip surgery. PE was assessed by pulmonary perfusion scintigraphy before and after operation. We defined a PE as any new scintigraphic defect which was larger than a bronchopulmonary segment. The incidence of PE was 55% in the control group and 21% in the treatment group. The foot sole pump significantly reduced the incidence of PE (p = 0.008) and we encountered no side-effects from its use.