Objectives. The goal of this study was to determine whether intra-articular administration of the potentially anti-fibrotic agent decorin influences the expression of genes involved in the fibrotic cascade, and ultimately leads to less contracture, in an animal model. Methods. A total of 18 rabbits underwent an operation on their right knees to form contractures. Six limbs in group 1 received four intra-articular injections of decorin; six limbs in group 2 received four intra-articular injections of bovine serum albumin (BSA) over eight days; six limbs in group 3 received no injections. The contracted limbs of rabbits in group 1 were biomechanically and genetically compared with the contracted limbs of rabbits in groups 2 and 3, with the use of a calibrated joint measuring device and custom microarray, respectively. Results. There was no statistical difference in the flexion contracture angles between those limbs that received intra-articular decorin versus those that received intra-articular BSA (66° vs 69°; p = 0.41). Likewise, there was no statistical difference between those limbs that received intra-articular decorin versus those who had no injection (66° vs 72°; p = 0.27). When compared with BSA, decorin led to a statistically significant increase in the mRNA expression of 12 genes (p < 0.01). In addition, there was a statistical change in the mRNA expression of three genes, when compared with those without injection. . Conclusions. In this model, when administered intra-articularly at eight weeks, 2 mg of decorin had no significant effect on joint contractures. However, our genetic analysis revealed a significant alteration in several fibrotic genes. Cite this article: Bone Joint Res 2014;3:82–8

Aims

The antidiabetic agent metformin inhibits fibrosis in various organs. This study aims to elucidate the effects of hyperglycaemia and metformin on knee joint capsule fibrosis in mice.

Aims

The aims of this study were to evaluate wear on the surface of cobalt-chromium (CoCr) femoral components used in total knee arthroplasty (TKA) and compare the wear of these components with that of ceramic femoral components.

Aims

Anterior cruciate ligament (ACL) rupture commonly leads to post-traumatic osteoarthritis, regardless of surgical reconstruction. This study uses standing MRI to investigate changes in contact area, contact centroid location, and tibiofemoral alignment between ACL-injured knees and healthy controls, to examine the effect of ACL reconstruction on these parameters.

Aims

Meniscal injuries are common and often induce knee pain requiring surgical intervention. To develop effective strategies for meniscus regeneration, we hypothesized that a minced meniscus embedded in an atelocollagen gel, a firm gel-like material, may enhance meniscus regeneration through cell migration and proliferation in the gel. Hence, the objective of this study was to investigate cell migration and proliferation in atelocollagen gels seeded with autologous meniscus fragments in vitro and examine the therapeutic potential of this combination in an in vivo rabbit model of massive meniscus defect.

Purpose of the Study. This study aims at investigating the effect of application time of bone cement on the cement-bone interface strength in two types of commercially available bone cements, Cement-A and Cement-B. Materials and methods. Cement-A and Cement-B were applied to cancellous bone specimens at two different times; 2 and 4 minutes (min). The bone specimens were formulated from bovine bone. Specimens were loaded to failure and the force at which the cement-bone interface failed was recorded. The shear strength of the cement-bone interface was calculated by dividing the force at failure by the cross-sectional surface area of the cement-bone interface. Results. The mean (± standard deviation) and median (inter-quartile range) shear strength of the cement-bone interface was 2.79 ± 1.29 MPa and 2.29 (2.34) MPa for Cement-A applied at 2 min; 1.35 ± 0.89 MPa and 1.35 (1.74) MPa for Cement-A applied at 4 min; 2.93 ± 1.21 MPa and 3.01 (2.61) MPa for Cement-B applied at 2 min; and 3.00 ± 1.11 MPa and 2.92 (1.61) MPa for Cement-B applied at 4 min. Compared to all other groups, the cement-bone interface strength was significantly lower when Cement-A was applied to the bone specimens at 4 min (p < 0.05). There was no significant difference in the cement-bone interface strength when Cement-B was applied to bone at 2 and at 4 min. Conclusions. Under these testing conditions, the cement-bone interface strength did not seem to be affected by the time of application of Cement-B to bone. However, it was significantly lower when Cement-A was applied to bone at 4 min

Purpose. To determine the effect that Titanium Nitride (TiN) coatings have on wear rates of ultra high molecular weight polyethylene (UHMWPE). Background. Ceramic coatings have been shown to confer advantageous countersurface scratch resistance in knee arthroplasty. This may reduce UHMWPE wear rates and revision rates. Dermal hypersensitivity is a common problem with metals; TiN, a ceramic surface, has been used to prevent it. There is little data in the literature regarding the effect of TiN on UHMWPE. Materials and methods. A six station pin-on-plate testing machine cycled three cobalt chrome pins and three TiN-coated cobalt chrome pins against six gamma-irradiated UHMWPE plates at 1 Hz at 20°C. A lubricating solution of 30% bovine calf serum, 1% sodium azide and deionised water was used. Three gamma-irradiated UHMWPE plates served as soak controls. Average surface roughness of the pins was measured by surface profilometry. Scanning electron micrographs were taken after 0, 10, 100, 1000, 10000, 100000 and 1000000 cycles, with plate mass measured at 0, 10000, 100000 and 1000000 cycles. Results. There was a significant effect of cycles upon surface roughness, with increased number of cycles leading to an increase in surface roughness (p<0.01). No significant main effect was found of coating group upon average surface roughness of pins (p>0.07). There was no observed significant main effect of increasing number of cycles upon plate mass (p>0.05) or of pin group upon plate mass (p>0.05). Conclusion. A significant effect was shown of cycles upon surface roughness. However, a lack of other significant findings indicates additional research is required to fully determine titanium nitride's potential in knee arthroplasty

This study evaluates high power low frequency ultrasound transmitted via a flat vibrating probe tip as an alternative technology for meniscal debridement in the knee. A limitation of this technology is thermal damage in residual meniscal tissue. An experimental force controlled testing rig was constructed using a 20kHz ultrasonic probe suspended vertically from a load cell. Ex-vivo bovine meniscus samples were harvested from knee joints and cut into uniform 16mm discs. Effect of variation in force (2.5-4.5N) and amplitude of distal tip displacement (242-494μm peak-peak) settings on tissue removal rate (TRR) and penetration rate (PR) was analysed. Temperature elevation in the residual meniscus was measured by embedded thermocouples and residual meniscus histological analysis. The experiment was designed using a response surface quadratic model with input variables treated as continuous, using Design-Expert v.8.0 (Stat-Ease Inc., Minneapolis, MN). Statistical analysis was conducted using PASW Statistics v.18.0 (IBM SPSS Inc., Chicago, IL). As either force or amplitude increases, there is a linear increase in TRR (Mean±SD: 0.9±0.4 to 11.2±4.9mg/s). A corresponding increase is observed in PR (Mean±SD: 0.08±0.04 to 0.73±0.18mm/s). Maximum mean temperatures of 84.6±12.1°C and 52.3±10.9°C were recorded in residual tissue at 2mm and 4mm from the ultrasound probe-tissue interface. Minimum depth of the zone of thermal alteration in residual tissue was 177.4μm. There is an inverse relationship between both amplitude and force, and temperature elevation, with higher amplitude and force settings resulting in less thermal damage. Ultrasonic debridement shows comparable thermal damage to existing meniscal debridement technologies

Aims

Proliferation, migration, and differentiation of anterior cruciate ligament (ACL) remnant and surrounding cells are fundamental processes for ACL reconstruction; however, the interaction between ACL remnant and surrounding cells is unclear. We hypothesized that ACL remnant cells preserve the capability to regulate the surrounding cells’ activity, collagen gene expression, and tenogenic differentiation. Moreover, extracorporeal shock wave (ESW) would not only promote activity of ACL remnant cells, but also enhance their paracrine regulation of surrounding cells.

Aims

The aim of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement, and smooth titanium alloy to inhibit staphylococci in an in vitro environment, based on the evaluation of the zone of inhibition (ZOI). The hypothesis was that there would be no significant difference in the inhibition of methicillin-sensitive or methicillin-resistant Staphylococcus aureus (MSSA/MRSA) between the two groups.

Aim

Mesenchymal stem cells (MSCs) have several properties that may support their use as an early treatment option for osteoarthritis (OA). This study investigated the role of multiple injections of allogeneic bone marrow-derived stem cells (BMSCs) to alleviate the progression of osteoarthritic changes in the various structures of the mature rabbit knee in an anterior cruciate ligament (ACL)-deficient OA model.

Aims

It is increasingly appreciated that coordinated regulation of angiogenesis and osteogenesis is needed for bone formation. How this regulation is achieved during peri-implant bone healing, such as osseointegration, is largely unclear. This study examined the relationship between angiogenesis and osteogenesis in a unique model of osseointegration of a mouse tibial implant by pharmacologically blocking the vascular endothelial growth factor (VEGF) pathway.

Objectives

Bone void fillers are increasingly being used for dead space management in arthroplasty revision surgery. The aim of this study was to investigate the influence of calcium sulphate bone void filler (CS-BVF) on the damage and wear of total knee arthroplasty using experimental wear simulation.

Objectives

To compare the effect of femoral bone tunnel configuration on tendon-bone healing in an anterior cruciate ligament (ACL) reconstruction animal model.

Objectives

The lack of effective treatment for cartilage defects has prompted investigations using tissue engineering techniques for their regeneration and repair. The success of tissue-engineered repair of cartilage may depend on the rapid and efficient adhesion of transplanted cells to a scaffold. Our aim in this study was to repair full-thickness defects in articular cartilage in the weight-bearing area of a porcine model, and to investigate whether the CD44 monoclonal antibody biotin-avidin (CBA) binding technique could provide satisfactory tissue-engineered cartilage.

Objectives

The purpose of this study was to clarify the appearance of the reparative tissue on the articular surface and to analyse the properties of the reparative tissue after hemicallotasis osteotomy (HCO) using MRI T1ρ and T2 mapping.

The anatomy and microstructure of the menisci allow the effective distribution of load across the knee. Meniscectomy alters the biomechanical environment and is a potent risk factor for osteoarthritis. Despite a trend towards meniscus-preserving surgery, many tears are irreparable, and many repairs fail.

Meniscal allograft transplantation has principally been carried out for pain in patients who have had a meniscectomy. Numerous case series have reported a significant improvement in patient-reported outcomes after surgery, but randomised controlled trials have not been undertaken.

It is scientifically plausible that meniscal allograft transplantation is protective of cartilage, but this has not been established clinically to date.

Cite this article: Bone Joint J 2015; 97-B:590–4.

Previous studies support the important role of vascular endothelial growth factor (VEGF) and syndecan-4 in the pathogenesis of osteoarthritis (OA). Both VEGF and syndecan-4 are expressed by chondrocytes and both are involved in the regulation of matrix metalloproteinase-3, resulting in the activation of aggrecanase II (ADAMTS-5), which is essential in the pathogenesis of OA. However, the relationship between VEGF and syndecan-4 has not been established. As a pilot study, we assayed the expression of VEGF and syndecan-4 in cartilage samples and cultured chondrocytes from osteoarthritic knee joints and analysed the relationship between these two factors.

Specimens were collected from 21 female patients (29 knees) who underwent total knee replacement due to severe medial OA of the knee (Kellgren–Lawrence grade 4). Articular cartilage samples, obtained from bone and cartilage excised during surgery, were analysed and used for chondrocyte culture. We found that the levels of expression of VEGF and syndecan-4 mRNA did not differ significantly between medial femoral cartilage with severe degenerative changes and lateral femoral cartilage that appeared grossly normal (p = 0.443 and 0.622, respectively). Likewise, the levels of expression of VEGF and syndecan-4 mRNA were similar in cultured chondrocytes from medial and lateral femoral cartilage. The levels of expression of VEGF and syndecan-4 mRNAs were significantly and positively correlated in cartilage explant (r = 0.601, p = 0.003) but not in cultured chondrocytes. These results suggest that there is a close relationship between VEGF and syndecan-4 in the cartilage of patients with OA. Further studies are needed to determine the exact pathway by which these two factors interact in the pathogenesis of OA.

Cite this article: Bone Joint J 2014;96-B:1319–24.

We attempted to characterise the biological quality and regenerative potential of chondrocytes in osteochondritis dissecans (OCD). Dissected fragments from ten patients with OCD of the knee (mean age 27.8 years (16 to 49)) were harvested at arthroscopy. A sample of cartilage from the intercondylar notch was taken from the same joint and from the notch of ten patients with a traumatic cartilage defect (mean age 31.6 years (19 to 52)). Chondrocytes were extracted and subsequently cultured. Collagen types 1, 2, and 10 mRNA were quantified by polymerase chain reaction. Compared with the notch chondrocytes, cells from the dissecate expressed similar levels of collagen types 1 and 2 mRNA. The level of collagen type 10 message was 50 times lower after cell culture, indicating a loss of hypertrophic cells or genes. The high viability, retained capacity to differentiate and metabolic activity of the extracted cells suggests preservation of the intrinsic repair capability of these dissecates. Molecular analysis indicated a phenotypic modulation of the expanded dissecate chondrocytes towards a normal phenotype. Our findings suggest that cartilage taken from the dissecate can be reasonably used as a cell source for chondrocyte implantation procedures.

Focal femoral inlay resurfacing has been developed for the treatment of full-thickness chondral defects of the knee. This technique involves implanting a defect-sized metallic or ceramic cap that is anchored to the subchondral bone through a screw or pin. The use of these experimental caps has been advocated in middle-aged patients who have failed non-operative methods or biological repair techniques and are deemed unsuitable for conventional arthroplasty because of their age. This paper outlines the implant design, surgical technique and biomechanical principles underlying their use. Outcomes following implantation in both animal and human studies are also reviewed.

Cite this article: Bone Joint J 2013;95-B:301–4.