Femoral morphology asymmetry in hip dysplasia makes radiological leg length measurement inaccurate.

AIMS: The aim of this study was to examine whether hips with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH) have significant asymmetry in femoral length, and to determine potential related factors. PATIENTS AND METHODS: We enrolled 90 patients (82 female, eight male) with DDH showing unilateral OA changes, and 43 healthy volunteers (26 female, 17 male) as controls. The mean age was 61.8 years (39 to 93) for the DDH groups, and 71.2 years (57 to 84) for the control group. Using a CT-based coordinate measurement system, we evaluated the following vertical distances: top of the greater trochanter to the knee centre (femoral length GT), most medial prominence of the lesser trochanter to the knee centre (femoral length LT), and top of the greater trochanter to the medial prominence of the lesser trochanter (intertrochanteric distance), along with assessments of femoral neck anteversion and neck shaft angle. RESULTS: The percentages of hips with an absolute difference of > 5 mm in femoral GT and LT lengths were significantly larger in the DDH group (24% for both) compared with those of the control group (2% and 7%, respectively). The femoral length GT of the affected femur was significantly shorter in Crowe I and longer in Crowe IV than that of the unaffected side. The affected-to-unaffected difference of the intertrochanteric distance showed positive correlation with that of the femoral length GT in Crowe I and Crowe II/III, and negative correlation with that of the femoral length LT in the Crowe I and Crowe IV groups. CONCLUSION: Hips with unilateral end-stage OA secondary to DDH show significant asymmetry in femoral length between both the greater and lesser trochanter and the knee compared with controls. The intertrochanteric distance was a morphological factor related to femoral-length asymmetry. When undertaking total hip arthroplasty (THA) in the presence of DDH, long leg radiographs or CT measurements should be used to assess true leg-length discrepancy. Cite this article: Bone Joint J 2019;101-B:297-302.

A comparison of the effect of large and small metal-on-metal bearings in total hip arthroplasty on metal ion levels and the incidence of pseudotumour: a five-year follow-up of a previous report.

Aims: The purpose of this study was to compare two different types of metal-on-metal (MoM) bearing for total hip arthroplasty (THA): one with a large femoral head (38 mm to 52 mm) and the other with a conventional femoral head (28 mm or 32 mm). We compared clinical outcome, blood metal ion levels, and the incidence of pseudotumour in the two groups. Patients and Methods: Between December 2009 and December 2011, 62 patients underwent MoM THA with a large femoral head (Magnum group) and 57 patients an MoM THA with a conventional femoral head (conventional group). Clinical outcome was assessed using the Harris Hip score, University of California, Los Angeles (UCLA) activity score and EuroQol-5D (EQ-5D). Blood metal ion levels were measured and MRI scans were analyzed at a minimum of five years postoperatively. Results: No acetabular component was implanted with more than 50° of inclination in either group. The Harris Hip Score, UCLA activity score, and EQ-5D improved postoperatively in both groups; no significant clinical differences were noted between the groups. The blood cobalt ion levels in the conventional group continued to rise postoperatively to five years while reaching a plateau at two years postoperatively in the Magnum group. At five years, the mean cobalt ion level of 1.16 µg/l (sd 1.32) in the Magnum group was significantly lower than the 3.77 µg/l (sd 9.80) seen in the conventional group (p = 0.0015). The incidence of moderate to severe pseudotumour was 4.7% in the Magnum group and 20.6% in the conventional group. There were no dislocations in the Magnum group and two in the conventional group. One patient in the Magnum group underwent revision for pseudotumour at 4.7 years postoperatively. Conclusion: At five years, a well-positioned large head MoM THA has a significantly lower level of metal ion release and a lower incidence of moderate to severe pseudotumour than a MoM bearing of conventional size. Cite this article: Bone Joint J 2018;100-B:1018-24.

Olefin hydrosilylation catalyzed by cationic nickel(ii) allyl complexes: a non-innocent allyl ligand-assisted mechanism.

The arene-supported cationic nickel allyl complexes serve as good catalysts for olefin hydrosilylation at room temperature. Detailed mechanistic studies based on experiments and DFT calculations support the novel mechanism, which includes the facile Si-H bond cleavage and Si-C bond formation, assisted by a non-innocent allyl ligand.

Compressive properties of cartilage-like tissues repaired in vivo with scaffold-free, tissue engineered constructs.

BACKGROUND: It is crucial to develop an effective methodology for restoring adequate compressive properties to osteoarthritic cartilage. We have developed a scaffold-free tissue engineered construct cultured from synovium-derived mesenchymal stem cells. However, the compressive properties of cartilage-like tissues repaired with the construct have not been fully determined. METHODS: Synovium-derived mesenchymal stem cells were cultured in Dulbecco's modified Eagle's medium to produce the tissue engineered construct. Implantation of the construct into cylindrically-shaped partial defects in femoral cartilage in an experimental porcine model was performed. Six months after implantation, cartilage-like tissues repaired with the construct were subjected to static and cyclic compression tests using a micro-unconfined compression test apparatus developed in our laboratory. FINDINGS: The developed apparatus was validated in preliminary examinations. The repaired tissues exhibited rate-dependent viscoelastic properties; the compressive modulus was slightly lower than that of normal cartilage at a rate of 4 microm/s, while no difference was observed at a rate of 100 microm/s. In contrast, the repaired tissue without the construct exhibited rate-independent, non-viscoelastic properties. In the cyclic compression test, however, the compressive strain was significantly larger in both repaired tissues as compared with normal cartilage. INTERPRETATION: Although the quasi-static compressive properties of the repaired tissue with the construct, indicating rate-dependent and viscoelastic behaviors, are comparable to normal cartilage, the cyclic compressive strain increases more rapidly than in normal cartilage. It is suggested that the differences between the tissues and normal cartilage are attributable to the increased permeability of the extracellular matrix.

Comparison of human serum with fetal bovine serum for expansion and differentiation of human synovial MSC: potential feasibility for clinical applications.

The aim of this study was to evaluate the effect of human serum (HS) on growth and differentiation capacity of human synovium-derived mesenchymal stem cells (MSC) in comparison to cells grown in fetal bovine serum (FBS). Human MSCs were isolated from the synovium of knee joints of three donors and the cells were cultured individually in varying concentrations of allogenic HS or FBS. Bovine MSCs were isolated from synovium and cultured in the same manner. Cell proliferation was assessed by the tetrazolium assay after passage 3. The capacity for chondrogenic and osteogenic differentiation was investigated in specific media followed by 1,9-dimethylmethylene blue assay and alcian blue staining, or by alizarin red staining, respectively. Human MSCs proliferated significantly more rapidly in the presence of HS than with equivalent levels of FBS. Chondrogenic or osteogenic differentiation occurred to nearly identical levels in HS or FBS. The results of this study indicate that HS is superior for the culture of human MSCs compared with FBS in terms of cellular expandability, without losing chondrogenic or osteogenic differentiation capacity. Coupled with the advantage in eliminating the potential risk accompanied with the use of xeno-derived materials, pooled, well-characterized HS could be a useful reagent to promote cellular expansion for clinical synovial stem cell-based therapy.

The immunosuppressant FK506 promotes development of the chondrogenic phenotype in human synovial stromal cells via modulation of the Smad signaling pathway.

OBJECTIVE: To assess the effect of the immunosuppressant FK506 on chondrogenic differentiation of human synovial stromal cells (hSSCs). METHODS: hSSCs were isolated from synovium of the knee joint and 2x10(5) cells were subjected to pellet culture in chondrogenic culture medium for 3 weeks with or without growth factors [bone morphogenetic protein 2 (BMP2) or transforming growth factor beta(1) (TGFbeta(1))] and +/- addition of FK506 in chondrogenic culture media was evaluated. Chondrogenesis was assessed by the size of the pellet, the production of proteoglycans, and messenger RNA (mRNA) levels for chondrogenic markers. Furthermore, levels and intracellular location of phosphorylated Smad proteins related to BMP signaling and TGFbeta signaling were evaluated following exposure to FK506. RESULTS: FK506 enhanced the differentiation of hSSCs toward a chondrogenic phenotype in a dose-dependent manner associated with increases in glycosaminoglycan synthesis and increased mRNA levels for chondrogenic marker genes. Additionally, FK506 further enhanced chondrogenesis of synovial stromal cells (SSCs) induced by BMP2 and TGFbeta(1), also in a dose-dependent manner. Notably, phosphorylation of Smad1/5/8 and Smad3 was significantly increased by FK506. Also, the ratio of nuclear translocation to cytoplasmic levels of phosphorylated Smad1/5/8 and Smad3 were increased following exposure of SSCs to FK506. Moreover, inhibition of Smad signaling significantly abrogated FK506-induced chondrogenic differentiation of SSCs. CONCLUSION: This study demonstrated that FK506 promotes chondrogenic differentiation of hSSCs likely via impact on Smad signaling pathways. With further optimization, FK506 could potentially be a unique therapeutic tool to promote cartilage repair in clinical situations, as well as enhance development of tissue engineered cartilage in vitro.

A first photochemical bis-germylation of C60 with digermirane

[reaction: see text]In the photochemical bis-germylation of C60 with 1,1,2,2-tetrakis(2,6-diethylphenyl)-1,2-digermirane (1), a cycloadduct (2) is obtained in high yield for the first time. Spectroscopic analysis and theoretical investigation confirm that 2 (which has C1 symmetry) results from 1,4-cycloaddition. Control experiments and laser flash photolysis experiments suggest that an exciplex intermediate is responsible for the formation of 2. The redox properties of 2 were examined by differential pulse voltammetry.