Objectives. Osteoporosis has become an increasing concern for older people as it may potentially lead to osteoporotic fractures. This study is designed to assess the efficacy and safety of ten therapies for post-menopausal women using network meta-analysis. Methods. We conducted a systematic search in several databases, including PubMed and Embase. A random-effects model was employed and results were assessed by the odds ratio (OR) and corresponding 95% confidence intervals (CI). Furthermore, with respect to each outcome, each intervention was ranked according to the surface under the cumulative ranking curve (SUCRA) value. Results. With respect to preventing new vertebral fractures (NVF), all ten drugs outperformed placebo, and etidronate proved to be the most effective treatment (OR 0.24, 95% CI 0.14 to 0.39). In addition, zoledronic acid and parathyroid hormone ranked higher compared with the other drugs. With respect to preventing clinical vertebral fractures (CVF), zoledronic acid proved to be the most effective drug (OR = 0.25, 95% CI 0.08 to 0.92), with denosumab as a desirable second option (OR = 0.48, 95% CI 0.22 to 0.96), when both were compared with placebo. As for adverse events (AE) and severe adverse events (SAE), no significant difference was observed. According to SUCRA, etidronate ranked first in preventing CVF; parathyroid hormone and zoledronic acid ranked highly in preventing NVF and CVF. Raloxifene was safe with a high rank in preventing AEs and SAEs though performed unsatisfactorily in efficacy. Conclusions. This study suggests that, taking efficacy and safety into account, parathyroid hormone and zoledronic acid had the highest probability of satisfactory performance in preventing osteoporotic fractures. Cite this article: G. Wang, L. Sui, P. Gai, G. Li, X. Qi, X. Jiang. The efficacy and safety of vertebral fracture prevention therapies in post-menopausal osteoporosis treatment: Which therapies work best? a network meta-analysis. Bone Joint Res 2017;6:452–463. DOI: 10.1302/2046-3758.67.BJR-2016-0292.R1

We studied peridural fibrosis in 16 dogs after laminectomies at the L2, L4 and L6 levels. They received either a free fat graft, a biodegradable mechanical barrier (polyethylene oxide (PEO)/polybutylene terephthalate (PBT) copolymer), or no treatment. The animals were killed after 4, 12, 26 and 52 weeks.

Histomorphometry showed extensive and consistent peridural fibrosis in control and PEO/PBT groups. Fat grafts produced significantly less fibrous tissue, but the presence of the fat graft in the bony defect prevented closure. Degradation of the PEO/PBT barrier resulted in the formation of more fibrous tissue.

We conclude that up to one year a free fat graft is effective in reducing the amount of peridural scarring.

Objectives

To review the current best surgical practice and detail a multi-disciplinary approach that could further reduce joint replacement infection.

Dislocation remains a major concern after total hip replacement, and is often attributed to malposition of the components. The optimum position for placement of the components remains uncertain. We have attempted to identify a relatively safe zone in which movement of the hip will occur without impingement, even if one component is positioned incorrectly. A three-dimensional computer model was designed to simulate impingement and used to examine 125 combinations of positioning of the components in order to allow maximum movement without impingement. Increase in acetabular and/or femoral anteversion allowed greater internal rotation before impingement occurred, but decreases the amount of external rotation. A decrease in abduction of the acetabular components increased internal rotation while decreasing external rotation. Although some correction for malposition was allowable on the opposite side of the joint, extreme degrees could not be corrected because of bony impingement.

We introduce the concept of combined component position, in which anteversion and abduction of the acetabular component, along with femoral anteversion, are all defined as critical elements for stability.

We evaluated the effects of a serum protein coating on prosthetic infection in 29 adult male rabbits divided into three groups: control, albumin-coated and uncoated. We used 34 grit-blasted, commercially pure titanium implants. Eleven were coated with cross-linked albumin. All the implants were exposed to a suspension of Staphylococcus epidermidis before implantation.

Our findings showed that albumin-coated implants had a much lower infection rate (27%) than the uncoated implants (62%). This may be a useful method of reducing the infection of prostheses.

This edition of Cochrane Corner looks at some of the work published by the Cochrane Collaboration, covering pharmacological interventions for the prevention of bleeding in people undergoing definitive fixation or joint replacement for hip, pelvic, and long bone fractures; interventions for reducing red blood cell transfusion in adults undergoing hip fracture surgery: an overview of systematic reviews; and pharmacological treatments for low back pain in adults: an overview of Cochrane Reviews

The Cochrane Collaboration has produced five new reviews relevant to bone and joint surgery since the publication of the last Cochrane Corner These reviews are relevant to a wide range of musculoskeletal specialists, and include reviews in Morton’s neuroma, scoliosis, vertebral fractures, carpal tunnel syndrome, and lower limb arthroplasty.

Objectives. Interleukin 18 (IL-18) is a regulatory cytokine that degrades the disc matrix. Bone morphogenetic protein-2 (BMP-2) stimulates synthesis of the disc extracellular matrix. However, the combined effects of BMP-2 and IL-18 on human intervertebral disc degeneration have not previously been reported. The aim of this study was to investigate the effects of the anabolic cytokine BMP-2 and the catabolic cytokine IL-18 on human nucleus pulposus (NP) and annulus fibrosus (AF) cells and, therefore, to identify potential therapeutic and clinical benefits of recombinant human (rh)BMP-2 in intervertebral disc degeneration. Methods. Levels of IL-18 were measured in the blood of patients with intervertebral disc degenerative disease and in control patients. Human NP and AF cells were cultured in a NP cell medium and treated with IL-18 or IL-18 plus BMP-2. mRNA levels of target genes were measured by real-time polymerase chain reaction, and protein levels of aggrecan, type II collagen, SOX6, and matrix metalloproteinase 13 (MMP13) were assessed by western blot analysis. Results. The serum level of patients (IL-18) increased significantly with the grade of IVD degeneration. There was a dramatic alteration in IL-18 level between the advanced degeneration (Grade III to V) group and the normal group (p = 0.008) Furthermore, IL-18 induced upregulation of the catabolic regulator MMP13 and downregulation of the anabolic regulators aggrecan, type II collagen, and SOX6 at 24 hours, contributing to degradation of disc matrix enzymes. However, BMP-2 antagonised the IL-18 induced upregulation of aggrecan, type II collagen, and SOX6, resulting in reversal of IL-18 mediated disc degeneration. Conclusions. BMP-2 is anti-catabolic in human NP and AF cells, and its effects are partially mediated through provocation of the catabolic effect of IL-18. These findings indicate that BMP-2 may be a unique therapeutic option for prevention and reversal of disc degeneration. Cite this article: S. Ye, B. Ju, H. Wang, K-B. Lee. Bone morphogenetic protein-2 provokes interleukin-18-induced human intervertebral disc degeneration. Bone Joint Res 2016;5:412–418. DOI: 10.1302/2046-3758.59.BJR-2016-0032.R1

High-intensity narrow-spectrum (HINS) light is a novel violet-blue light inactivation technology which kills bacteria through a photodynamic process, and has been shown to have bactericidal activity against a wide range of species. Specimens from patients with infected hip and knee arthroplasties were collected over a one-year period (1 May 2009 to 30 April 2010). A range of these microbial isolates were tested for sensitivity to HINS-light. During testing, suspensions of the pathogens were exposed to increasing doses of HINS-light (of 123mW/cm. 2. irradiance). Non-light exposed control samples were also used. The samples were then plated onto agar plates and incubated at 37°C for 24 hours before enumeration. Complete inactivation (greater than 4-log. 10. reduction) was achieved for all of the isolates. The typical inactivation curve showed a slow initial reaction followed by a rapid period of inactivation. The doses of HINS-light required ranged between 118 and 2214 J/cm. 2. Gram-positive bacteria were generally found to be more susceptible than Gram-negative. As HINS-light uses visible wavelengths, it can be safely used in the presence of patients and staff. This unique feature could lead to its possible use in the prevention of infection during surgery and post-operative dressing changes. Cite this article: Bone Joint J 2015;97-B:283–8

We have developed an animal model to examine the formation of heterotopic ossification using standardised muscular damage and implantation of a beta-tricalcium phosphate block into a hip capsulotomy wound in Wistar rats. The aim was to investigate how cells originating from drilled femoral canals and damaged muscles influence the formation of heterotopic bone. The femoral canal was either drilled or left untouched and a tricalcium phosphate block, immersed either in saline or a rhBMP-2 solution, was implanted. These implants were removed at three and 21 days after the operation and examined histologically, histomorphometrically and immunohistochemically. Bone formation was seen in all implants in rhBMP-2-immersed, whereas in those immersed in saline the process was minimal, irrespective of drilling of the femoral canals. Bone mineralisation was somewhat greater in the absence of drilling with a mean mineralised volume to mean total volume of 18.2% (. sd. 4.5) versus 12.7% (. sd. 2.9, p < 0.019), respectively. Our findings suggest that osteoinductive signalling is an early event in the formation of ectopic bone. If applicable to man the results indicate that careful tissue handling is more important than the prevention of the dissemination of bone cells in order to avoid heterotopic ossification

The aim of this study was to determine the effectiveness of antibiotic-impregnated implants in the prevention of bone infection. We used a model of contaminated fracture in goats to evaluate four treatment groups: no treatment, hand-made tobramycin-impregnated polymethylmethacrylate beads, commercially-available tobramycin-impregnated calcium sulphate pellets and commercially-available tobramycin-impregnated polymethylmethacrylate beads. Three weeks after intraosseous inoculation with streptomycin-resistant Staphylococcus aureus tissue cultures showed no evidence of infection in any of the antibiotic-treated groups. All of the cultures were positive in the untreated group. These results show that effective local antibiotic delivery can be obtained with both commercially-available products and with hand-made polymethylmethacrylate beads. The calcium sulphate pellets have the advantage of being bioabsorbable, thereby obviating the need for a second procedure to remove them

Compartment syndrome is a unique form of ischaemia of skeletal muscle which occurs despite patency of the large vessels. Decompression allows the influx of activated leucocytes which cause further injury. Vitamin C is a powerful antioxidant which concentrates preferentially in leucocytes and attenuates reperfusion-induced muscle injury. We have evaluated the use of pretreatment with oral vitamin C in the prevention of injury caused by compartment syndrome in a rat cremasteric muscle model. Acute and delayed effects of pretreatment with vitamin C were assessed at one and 24 hours after decompression of compartment syndrome. Muscle function was assessed electrophysiologically. Vascular, cellular and tissue inflammation was assessed by staining of intercellular adhesion molecule-1 (ICAM-1) and by determination of the activity of myeloperoxidase (MPO) in neutrophils and tissue oedema. Compartment syndrome impaired skeletal muscle function and increased the expression of ICAM-1, activity of MPO and muscle weight increased significantly. Pretreatment with vitamin C preserved muscle function and reduced the expression of ICAM-1, infiltration of the neutrophils and oedema

Ischaemia-reperfusion injury (IRI) is caused by endothelial and subendothelial damage by neutrophil-derived oxidants. Vitamin C is an antioxidant which attenuates endothelial injury after IRI. Our aim was to evaluate the effect of oral vitamin C in the prevention of IRI in skeletal muscle. We used a model of cross-clamping (3 hours) and reperfusion (1 hour) of the cremaster muscle in rats. Muscle function was assessed electrophysiologically by electrical field stimulation. Infiltration by neutrophils was determined by the activity of tissue myeloperoxidase (MPO) and tissue oedema by the wet-to-dry ratio. Neutrophil respiratory burst activity was measured in control animals and groups pretreated with vitamin C. IRI significantly decreased muscle function and increased muscle neutrophil MPO activity and muscle oedema. Pretreatment with vitamin C preserved muscle function and reduced tissue oedema and neutrophil infiltration. Neutrophil respiratory burst activity was reduced in the group treated with vitamin C compared with the control group. We conclude that pretreatment with oral vitamin C protects against acute muscle IRI, possibly by attenuating neutrophil respiratory burst activity

We have studied the relationship between movements of the foot and ankle and venous blood flow from the lower limb using colourflow Duplex ultrasound to determine the optimum type of exercise for promoting venous return. Studies of both active and passive movements were carried out on 40 limbs in 20 subjects (18 men; 2 women), with a median age of 27 years (20 to 54). We assessed ankle dorsiflexion and plantar flexion, subtalar inversion and eversion, and a combination of all movements. There was no difference in venous flow when comparing opposite limbs in a single subject (p > 0.5), but active exercises produced higher peak and mean velocities of blood flow than passive ones. The active combined movement produced the highest velocities with an increase of 38% in mean and of 58% in peak flow velocities, which were significantly greater than the peak and mean flow rates produced by passive movements. The active combined exercise would therefore be the most effective in eliminating stasis and could contribute to the prevention of deep-vein thrombosis

We have studied the beneficial effects of a hydroxyapatite (HA) coating on the prevention of the migration of wear debris along the implant-bone interface. We implanted a loaded HA-coated implant and a non-coated grit-blasted titanium alloy (Ti) implant in each distal femoral condyle of eight Labrador dogs. The test implant was surrounded by a gap communicating with the joint space and allowing access of joint fluid to the implant-bone interface. We injected polyethylene (PE) particles into the right knee three weeks after surgery and repeated this weekly for the following five weeks. The left knee received sham injections. The animals were killed eight weeks after surgery. Specimens from the implant-bone interface were examined under plain and polarised light. Only a few particles were found around HA-coated implants, but around Ti implants there was a large amount of particles. HA-coated implants had approximately 35% bone ingrowth, whereas Ti implants had virtually no bone ingrowth and were surrounded by a fibrous membrane. Our findings suggest that HA coating of implants is able to inhibit peri-implant migration of PE particles by creating a seal of tightly-bonded bone on the surface of the implant

Objectives

Adult mice lacking the transcription factor NFAT1 exhibit osteoarthritis (OA). The precise molecular mechanism for NFAT1 deficiency-induced osteoarthritic cartilage degradation remains to be clarified. This study aimed to investigate if NFAT1 protects articular cartilage (AC) against OA by directly regulating the transcription of specific catabolic and anabolic genes in articular chondrocytes.

Objectives

The aim of this study was to investigate the role of miR-126 in the development of osteoarthritis, as well as the potential molecular mechanisms involved, in order to provide a theoretical basis for osteoarthritis treatment and a novel perspective for clinical therapy.

Aim

Osteoarthritis (OA) is caused by complex interactions between genetic and environmental factors. Epigenetic mechanisms control the expression of genes and are likely to regulate the OA transcriptome. We performed integrative genomic analyses to define methylation-gene expression relationships in osteoarthritic cartilage.

Objectives

Degenerative disc disease (DDD) and osteoarthritis (OA) are relatively frequent causes of disability amongst the elderly; they constitute serious socioeconomic costs and significantly impair quality of life. Previous studies to date have found that aggrecan variable number of tandem repeats (VNTR) contributes both to DDD and OA. However, current data are not consistent across studies. The purpose of this study was to evaluate systematically the relationship between aggrecan VNTR, and DDD and/or OA.

Osteoporosis is a systemic skeletal disorder characterized by reduced bone mass and deterioration of bone microarchitecture, which results in increased bone fragility and fracture risk. Casein kinase 2-interacting protein-1 (CKIP-1) is a protein that plays an important role in regulation of bone formation. The effect of CKIP-1 on bone formation is mainly mediated through negative regulation of the bone morphogenetic protein pathway. In addition, CKIP-1 has an important role in the progression of osteoporosis. This review provides a summary of the recent studies on the role of CKIP-1 in osteoporosis development and treatment.

Cite this article: X. Peng, X. Wu, J. Zhang, G. Zhang, G. Li, X. Pan. The role of CKIP-1 in osteoporosis development and treatment. Bone Joint Res 2018;7:173–178. DOI: 10.1302/2046-3758.72.BJR-2017-0172.R1.

Objectives

Bisphosphonates (BP) are the first-line treatment for preventing fragility fractures. However, concern regarding their efficacy is growing because bisphosphonate is associated with over-suppression of remodelling and accumulation of microcracks. While dual-energy X-ray absorptiometry (DXA) scanning may show a gain in bone density, the impact of this class of drug on mechanical properties remains unclear. We therefore sought to quantify the mechanical strength of bone treated with BP (oral alendronate), and correlate data with the microarchitecture and density of microcracks in comparison with untreated controls.

Objectives

Sustained intra-articular delivery of pharmacological agents is an attractive modality but requires use of a safe carrier that would not induce cartilage damage or fibrosis. Collagen scaffolds are widely available and could be used intra-articularly, but no investigation has looked at the safety of collagen scaffolds within synovial joints. The aim of this study was to determine the safety of collagen scaffold implantation in a validated in vivo animal model of knee arthrofibrosis.

Objectives

Surgeons face a substantial risk of infection because of the occupational exposure to blood-borne pathogens (BBPs) from patients undergoing high-risk orthopaedic procedures. This study aimed to determine the seroprevalence of four BBPs among patients undergoing joint arthroplasty in Shanghai, China. In addition, we evaluated the significance of pre-operative screening by calculating a cost-to-benefit ratio.

Objectives

Implant-related infection is one of the most devastating complications in orthopaedic surgery. Many surface and/or material modifications have been developed in order to minimise this problem; however, most of the in vitro studies did not evaluate bacterial adhesion in the presence of eukaryotic cells, as stated by the ‘race for the surface’ theory. Moreover, the adherence of numerous clinical strains with different initial concentrations has not been studied.

Objectives

Recent studies have shown that systemic injection of rapamycin can prevent the development of osteoarthritis (OA)-like changes in human chondrocytes and reduce the severity of experimental OA. However, the systemic injection of rapamycin leads to many side effects. The purpose of this study was to determine the effects of intra-articular injection of Torin 1, which as a specific inhibitor of mTOR which can cause induction of autophagy, is similar to rapamycin, on articular cartilage degeneration in a rabbit osteoarthritis model and to investigate the mechanism of Torin 1’s effects on experimental OA.

Objectives

Venous thromboembolism (VTE) is a major potential complication following orthopaedic surgery. Subcutaneously administered enoxaparin has been used as the benchmark to reduce the incidence of VTE. However, concerns have been raised regarding the long-term administration of enoxaparin and its possible negative effects on bone healing and bone density with an increase of the risk of osteoporotic fractures. New oral anticoagulants such as rivaroxaban have recently been introduced, however, there is a lack of information regarding how these drugs affect bone metabolism and post-operative bone healing.

Objectives

To assess the sensitivity and specificity of self-reported osteoporosis compared with dual energy X-ray absorptiometry (DXA) defined osteoporosis, and to describe medication use among participants with the condition.

We analysed the effects of commonly used medications on human osteoblastic cell activity in vitro, specifically proliferation and tissue mineralisation. A list of medications was retrieved from the records of patients aged > 65 years filed in the database of the largest health maintenance organisation in our country (> two million members). Proliferation and mineralisation assays were performed on the following drugs: rosuvastatin (statin), metformin (antidiabetic), metoprolol (β-blocker), citalopram (selective serotonin reuptake inhibitor [SSRI]), and omeprazole (proton pump inhibitor (PPI)). All tested drugs significantly stimulated DNA synthesis to varying degrees, with rosuvastatin 5 µg/ml being the most effective among them (mean 225% (sd 20)), compared with metformin 10 µg/ml (185% (sd 10)), metoprolol 0.25 µg/ml (190% (sd 20)), citalopram 0.05 µg/ml (150% (sd 10)) and omeprazole 0.001 µg/ml (145% (sd 5)). Metformin and metoprolol (to a small extent) and rosuvastatin (to a much higher extent) inhibited cell mineralisation (85% (sd 5)). Our results indicate the need to evaluate the medications prescribed to patients in terms of their potential action on osteoblasts. Appropriate evaluation and prophylactic treatment (when necessary) might lower the incidence and costs associated with potential medication-induced osteoporosis.

Cite this article: Bone Joint J 2013;95-B:1575–80.

We investigated the effect of mitomycin-C on the reduction of the formation of peritendinous fibrous adhesions after tendon repair. In 20 Wistar albino rats the tendo Achillis was cut and repaired using a modified Kessler technique. The rats were divided into two equal groups. In group 1, an injection of mitomycin-C was placed between the tendon and skin of the right leg. In group 2, an identical volume of sterile normal saline was injected on the left side in a similar fashion. All the rats received mitomycin-C or saline for four weeks starting from the day of operation. The animals were killed after 30 days. The formation of peritendinous fibrous tissue, the inflammatory reaction and tendon healing were evaluated. The tensile strength of the repaired tendons was measured biomechanically. Microscopic evidence of the formation of adhesions and inflammation was less in group 1. There was no significant difference in the tensile load required to rupture the repaired tendons in the two groups.

Mitomycin-C may therefore provide a simple and inexpensive means of preventing of post-operative adhesions.

Objectives

We aimed to examine the characteristics of deep venous flow in the leg in a cast and the effects of a wearable neuromuscular stimulator (geko; FirstKind Ltd) and also to explore the participants’ tolerance of the stimulator.

We used a goat model of a contaminated musculoskeletal defect to determine the effectiveness of rapidly-resorbing calcium-sulphate pellets containing amikacin to reduce the local bacterial count. Our findings showed that this treatment eradicated the bacteria quickly, performed as well as standard polymethylmethacrylate mixed with an antibiotic and had many advantages over the latter. The pellets were prepared before surgery and absorbed completely. They released all of the antibiotic and did not require a subsequent operation for their removal. Our study indicated that locally administered antibiotics reduced bacteria within the wound rapidly. This method of treatment may have an important role in decreasing the rate of infection in contaminated wounds.

Although much has been published on the causes of slipped upper femoral epiphysis and the results of treatment, little attention has been given to the mechanism of the slip. This study presents the results of the analysis of 13 adolescent femora, and the attempts to reproduce the radiological appearances of a typical slip. The mean age of the skeletons was 13 years (11 to 15). It was found that the internal bony architecture in the zone of the growth plate was such that a slip of the epiphysis on the metaphysis (in the normal meaning of the word slip) could not take place, largely relating to the presence of a tubercle of bone projecting down from the epiphysis. The only way that the appearance of a typical slipped upper femoral epiphysis could be reproduced was by rotating the epiphysis posteromedially on the metaphysis. The presence and size of this peg-like tubercle was shown radiologically by CT scanning in one pair of intact adolescent femurs.

We stably transfected early passage chondrocytes with an anti-apoptotic Bcl-2 gene in vitro using a retrovirus vector. Samples of articular cartilage were obtained from 11 patients with a mean age of 69 years (61 to 75) who were undergoing total knee replacement for osteoarthritis. The Bcl-2-gene-transfected chondrocytes were compared with non-transfected and lac-Z-gene-transfected chondrocytes, both of which were used as controls. All three groups of cultured chondrocytes were incubated with nitric oxide (NO) for ten days. Using the Trypan Blue exclusion assay, an enzyme-linked immunosorbent assay and flow cytometric analysis, we found that the number of apoptotic chondrocytes was significantly higher in the non-transfected and lac-Z-transfected groups than in the Bcl-2-transfected group (p < 0.05). The Bcl-2-transfected chondrocytes were protected from NO-induced impairment of proteoglycan synthesis.

We conclude that NO-induced chondrocyte death involves a mechanism which appears to be subject to regulation by an anti-apoptotic Bcl-2 gene. Therefore, Bcl-2 gene therapy may prove to be of therapeutic value in protecting human articular chondrocytes.

Impaction allograft is an established method of securing initial stability of an implant in arthroplasty. Subsequent bone integration can be prolonged, and the volume of allograft may not be maintained. Intermittent administration of parathyroid hormone has an anabolic effect on bone and may therefore improve integration of an implant.

Using a canine implant model we tested the hypothesis that administration of parathyroid hormone may improve osseointegration of implants surrounded by bone graft. In 20 dogs a cylindrical porous-coated titanium alloy implant was inserted into normal cancellous bone in the proximal humerus and surrounded by a circumferential gap of 2.5 mm. Morsellised allograft was impacted around the implant. Half of the animals were given daily injections of human parathyroid hormone (1–34) 5 μg/kg for four weeks and half received control injections. The two groups were compared by mechanical testing and histomorphometry. We observed a significant increase in new bone formation within the bone graft in the parathyroid hormone group. There were no significant differences in the volume of allograft, bone-implant contact or in the mechanical parameters.

These findings suggest that parathyroid hormone improves new bone formation in impacted morsellised allograft around an implant and retains the graft volume without significant resorption. Fixation of the implant was neither improved nor compromised at the final follow-up of four weeks.

We studied the effects of coating titanium implants with teicoplanin and clindamycin in 30 New Zealand White rabbits which were randomly assigned to three groups. The intramedullary canal of the left tibia of each rabbit was inoculated with 500 colony forming units of Staphylococcus aureus. Teicoplanin-coated implants were implanted into rabbits in group 1, clindamycin-coated implants into rabbits in group 2, and uncoated implants into those in group 3. All the rabbits were killed one week later. The implants were removed and cultured together with pieces of tibial bone and wound swabs. The rate of colonisation of the organisms in the three groups was compared.

Organisms were cultured from no rabbits in group 1, one in group 2 but from all in group 3. There was no significant difference between groups 1 and 2 (p = 1.000). There were significant differences between groups 1 and 3 and groups 2 and 3 (p < 0.001). Significant protection against bacterial colonisation and infection was found with teicoplanin- and clindamycin-coated implants in this experimental model.

We examined the mechanical properties of Vicryl (polyglactin 910) mesh in vitro and assessed its use in vivo as a novel biomaterial to attach tendon to a hydroxyapatite-coated metal implant, the interface of which was augmented with autogenous bone and marrow graft. This was compared with tendon re-attachment using a compressive clamp device in an identical animal model. Two- and four-ply sleeves of Vicryl mesh tested to failure under tension reached 5.13% and 28.35% of the normal ovine patellar tendon, respectively. Four-ply sleeves supported gait in an ovine model with 67.05% weight-bearing through the operated limb at 12 weeks, without evidence of mechanical failure.

Mesh fibres were visible at six weeks but had been completely resorbed by 12 weeks, with no evidence of chronic inflammation. The tendon-implant neoenthesis was predominantly an indirect type, with tendon attached to the bone-hydroxyapatite surface by perforating collagen fibres.

The reduced stability of hydroxyapatite (HA)-coated implants in osteopenic conditions is considered to be a major problem. We therefore developed a model of a boosted cementless implantation in osteopenic rats.

Twelve-week-old rats were either ovariectomised (OVX) or sham-operated (SO), and after 24 weeks plain or HA-coated implants were inserted. They were treated with either a prostaglandin EP4 receptor agonist (ONO-4819) or saline for one month.

The EP4 agonist considerably improved the osteoporosis in the OVX group. Ultrastructural analysis and mechanical testing showed an improvement in the implant-bone attachment in the HA-coated implants, which was further enhanced by the EP4 agonist. Although the stability of the HA-coated implants in the saline-treated OVX rats was less than in the SO normal rats, the administration of the EP4 agonist significantly compensated for this shortage. Our results showed that the osteogenic effect of the EP4 agonist augmented the osteoconductivity of HA and significantly improved the stability of the implant-bone attachment in the osteoporotic rat model.