Richard Appleyard

Osteoporosis influences the early period of fracture healing in a rat osteoporotic model

Osteoporotic fractures commonly occur in the elderly. Although current therapies are aimed at the prevention and treatment of osteoporotic fractures, studies examing the fracture healing process in osteoporotic bone are limited. We produced an osteoporotic rat model by ovariectomy (ovx) and maintained a low calcium diet (LCD) in order to evaluate the influence of osteoporosis on fracture healing. Callus formation and strength was monitored over a 3 week period by histological and biomechanical assessment. Data collected simultaneously on a group of rats undergoing sham surgery (sx) were used for comparison. A 40% reduction in fracture callus cross-sectional area and a 23% reduction in bone mineral density in the healing femur of the ovx rats was observed on day 21 following fracture as compared with the sx group (p < 0.01). Biomechanical data from the healing femur of the ovx rats revealed a fivefold decrease in the energy required to break the fracture callus, a threefold decrease in peak failure load, a twofold decrease in stiffness and a threefold decrease in stress as compared with the sx group (p < 0.01, respectively). Histomorphological analysis revealed a delay in fracture callus healing with poor development of mature bone in the ovx rats. This study provides physical evidence of altered fracture healing in osteoporotic bone, which may have important implications in evaluating the effects of new treatments for osteoporosis on fracture healing.

The influence hydroxyapatite nanoparticle shape and size on the properties of biphasic calcium phosphate scaffolds coated with hydroxyapatite-PCL composites.

We developed a composite biphasic calcium phosphate (BCP) scaffold by coating a nanocomposite layer, consisting of hydroxyapatite (HA) nanoparticles and polycaprolactone (PCL), over the surface of BCP. The effects of HA particle size and shape in the coating layer on the mechanical and biological properties of the BCP scaffold were examined. Micro-computerized tomography studies showed that the prepared scaffolds were highly porous (approximately 91%) with large pore size (400-700 microm) and an interconnected porous network of approximately 100%. The HA nanoparticle (needle shape)-composite coated scaffolds displayed the highest compressive strength (2.1 +/- 0.17 MPa), compared to pure HA/beta-TCP (0.1 +/- 0.05 MPa) and to the micron HA - composite coated scaffolds (0.29 +/- 0.07 MPa). These needle shaped scaffolds also showed enhanced elasticity and similar stress-strain profile to natural bone. Needle shaped coated HA/PCL particles induced the differentiation of primary human bone derived cells, with significant upregulation of osteogenic gene expression (Runx2, collagen type I, osteocalcin and bone sialoprotein) and alkaline phosphatase activity compared to other groups. These properties are essential for enhancing bone ingrowth in load-bearing applications. The developed composite scaffolds possessed superior physical, mechanical, elastic and biological properties rendering them potentially useful for bone tissue regeneration.

Topical glyceryl trinitrate treatment of chronic noninsertional achilles tendinopathy: A randomized, double-blind, placebo-controlled trial

BACKGROUND Noninsertional Achilles tendinopathy is a degenerative overuse disorder. No method has been universally successful in treating this condition. Topically applied nitric oxide has been shown, in animal models, to be effective for the treatment of fractures and cutaneous wounds through mechanisms that may include stimulation of collagen synthesis in fibroblasts. The goal of the present study was to determine if topical glyceryl trinitrate improves clinical outcome measures in patients with Achilles tendinopathy. METHODS A prospective, randomized, double-blind, placebo-controlled trial involving a total of sixty-five patients (eighty-four Achilles tendons) was performed to compare continuous application of topical glyceryl trinitrate (at a dosage of 1.25 mg per twenty-four hours) with rehabilitation alone for the treatment of noninsertional Achilles tendinopathy. RESULTS Compared with the control group, the glyceryl trinitrate group showed reduced pain with activity at twelve weeks (p = 0.02) and twenty-four weeks (p = 0.03), reduced night pain at twelve weeks (p = 0.04), reduced tenderness at twelve weeks (p = 0.02), decreased pain scores after the hop test at twenty-four weeks (p = 0.005), and increased ankle plantar flexor mean total work compared with the baseline level at twenty-four weeks (p = 0.04). Twenty-eight (78%) of thirty-six tendons in the glyceryl trinitrate group were asymptomatic with activities of daily living at six months, compared with twenty (49%) of forty-one tendons in the placebo group (p = 0.001, chi-square analysis). The mean effect size for all outcome measures was 0.14. CONCLUSIONS Topical glyceryl trinitrate significantly reduced pain with activity and at night, improved functional measures, and improved outcomes in patients with Achilles tendinopathy.

Topical Nitric Oxide Application in the Treatment of Chronic Extensor Tendinosis at the Elbow A Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

Background: Extensor tendinosis (“tennis elbow”) is a degenerative overuse tendinopathy of the wrist extensors at their attachment to the lateral humeral epicondyle. No treatment has been universally successful. Topical application of nitric oxide has been used effectively to treat fractures and cutaneous wounds in animal models, presumably by stimulation of collagen synthesis in fibroblasts. Purpose: To determine whether topical nitric oxide can improve outcome of patients with extensor tendinosis. Study Design: Prospective, randomized, double-blinded clinical trial. Methods: Eighty-six patients with extensor tendinosis were randomized into two equal groups; both were instructed to perform a standard tendon rehabilitation program. One group received an active glyceryl trinitrate transdermal patch, and the other group received a placebo patch. Results: Patients in the glyceryl trinitrate group had significantly reduced elbow pain with activity at 2 weeks, reduced epicondylar tenderness at 6 and 12 weeks, and an increase in wrist extensor mean peak force and total work at 24 weeks. At 6 months, 81% of treated patients were asymptomatic during activities of daily living, compared with 60% of patients who had tendon rehabilitation alone. Conclusions: Application of topical nitric oxide improved early pain with activity, late functional measures, and outcomes of patients with extensor tendinosis.

The effect of mesoporous bioactive glass on the physiochemical, biological and drug-release properties of poly(DL-lactide-co-glycolide) films

Poly(lactide-co-glycolide) (PLGA) has been widely used for bone tissue regeneration. However, it lacks hydrophilicity, bioactivity and sufficient mechanical strength and its acidic degradation by-products can lead to pH decrease in the vicinity of the implants. Mesoporous bioactive glass (MBG) with highly ordered structure (pore size 2-50nm) possesses higher bioactivity than non-mesoporous bioactive glass (BG). The aim of this study is to investigate the effect of MBG on the mechanical strength, in vitro degradation, bioactivity, cellular response and drug release of PLGA films and optimize their physicochemical, biological and drug-delivery properties for bone tissue engineering application. The surface and inner microstructure, mechanical strength and surface hydrophilicity of MBG/PLGA and BG/PLGA films were tested. Results indicated that MBG or BG was uniformly dispersed in the PLGA films. The incorporation of MBG into PLGA films significantly improved their tensile strength, modulus and surface hydrophilicity. MBG/PLGA resulted in an enhanced mechanical strength, in vitro degradation (water absorbance, weight loss and ions release), apatite-formation ability and pH stability in simulated body fluids (SBF), compared to BG/PLGA. MBG/PLGA and BG/PLGA films enhanced human osteoblastic-like cells (HOBs) attachment, spreading and proliferation compared to PLGA. HOBs differentiation was significantly upregulated when cells were cultured on 30 MBG/PLGA for 14 days, compared to 30 BG/PLGA. MBG/PLGA enhanced the accumulative release of dexamethazone (DEX) at early stages (0-200h) compared to BG/PLGA, however, after 200h, DEX-release rates for MBG/PLGA was slower than that of BG/PLGA. The contents of MBG in PLGA films can control the amount of DEX released. Taken together, MBG/PLGA films possessed excellent physicochemical, biological and drug-release properties, indicating their potential application for bone tissue engineering by designing 3D scaffolds according to their corresponding compositions.

Shoulder Pain in Elite Swimmers: Primarily Due to Swim-volume-induced Supraspinatus Tendinopathy

Background/hypothesis Shoulder pain in elite swimmers is common, and its pathogenesis is uncertain. Hypothesis/study design The authors used a crosssectional study design to test Jobe’s hypothesis that repetitive forceful swimming leads to shoulder laxity, which in turn leads to impingement pain. Methods Eighty young elite swimmers (13–25 years of age) completed questionnaires on their swimming training, pain and shoulder function. They were given a standardised clinical shoulder examination, and tested for glenohumeral joint laxity using a non-invasive electronic laxometer. 52/80 swimmers also attended for shoulder MRI. Results 73/80 (91%) swimmers reported shoulder pain. Most (84%) had a positive impingement sign, and 69% of those examined with MRI had supraspinatus tendinopathy. The impingement sign and MRIdetermined supraspinatus tendinopathy correlated strongly (rs=0.49, p<0.00001). Increased tendon thickness correlated with supraspinatus tendinopathy (rs=0.37, p<0.01). Laxity correlated weakly with impingement pain (rs=0.23, p<0.05) and was not associated with supraspinatus tendinopathy (rs=0.14, p=0.32). The number of hours swum/week (rs=0.39, p<0.005) and weekly mileage (rs=0.34, p=0.01) both correlated significantly with supraspinatus tendinopathy. Swimming stroke preference did not. Conclusions These data indicate: (1) supraspinatus tendinopathy is the major cause of shoulder pain in elite swimmers; (2) this tendinopathy is induced by large amounts of swimming training; and (3) shoulder laxity per se has only a minimal association with shoulder impingement in elite swimmers. These findings are consistent with animal and tissue culture findings which support an alternate hypothesis: the intensity and duration of load to tendon fibres and cells cause tendinopathy, impingement and shoulder pain.

Effects of bioactive glass nanoparticles on the mechanical and biological behavior of composite coated scaffolds.

Biphasic calcium phosphates (BCP) scaffolds are widely used for bone tissue regeneration. However, brittleness, low mechanical properties and compromised bioactivities are, at present, their major disadvantages. In this study we coated the struts of a BCP scaffold with a nanocomposite layer consisting of bioactive glass nanoparticles (nBG) and polycaprolactone (PCL) (BCP/PCL-nBG) to enhance its mechanical and biological behavior. The effect of various nBG concentrations (1-90 wt.%) on the mechanical properties and in vitro behavior of the scaffolds was comprehensively examined and compared with that for a BCP scaffold coated with PCL and hydroxyapatite nanoparticles (nHA) (BCP/PCL-nHA) and a BCP scaffold coated with only a PCL layer (BCP/PCL). Introduction of 1-90 wt.% nBG resulted in scaffolds with compressive strengths in the range 0.2-1.45 MPa and moduli in the range 19.3-49.4 MPa. This trend was also observed for BCP/PCL-nHA scaffolds, however, nBG induced even better bioactivity and a faster degradation rate. The maximum compressive strength (increased ∼14 times) and modulus (increased ∼3 times) were achieved when 30 wt.% nBG was added, compared with BCP scaffolds. Moreover, BCP/PCL-nBG scaffolds induced the differentiation of primary human bone-derived cells (HOBs), with significant up-regulation of osteogenic gene expression for Runx2, osteopontin and bone sialoprotein, compared with the other groups.

The accuracy and reliability of a novel handheld dynamic indentation probe for analysing articular cartilage.

This study investigates the accuracy and reliability of a novel handheld indentation system designed to ascertain the dynamic biomechanical properties of articular cartilage. A series of standard elastomers were assessed with both the handheld indentation system and a bench-top dynamic indentation system to assess the accuracy of the instrument. Interoperator and intraoperator experiments were undertaken to investigate the reliability of the system when used by an individual operator and by five different operators. Intraclass coefficients (Rho) were derived using a random effects model. The system was then used to ascertain the topographical variation in the shear moduli and phase lag of articular cartilage across normal ovine tibial plateaux. The system was shown to be highly accurate (R2 = 0.97), and had excellent reliability when measuring the dynamic shear modulus of articular cartilage (interoperator Rho = 0.75, intraoperator Rho = 0.79). Measurement of static shear modulus was less reliable (interoperator Rho = 0.15, intraoperator Rho = 0.52), but may be improved by monitoring the load applied to the instrument by the operator. The instrument was used to differentiate between different regions of cartilage and generated a topographical map of an ovine tibial plateau. The cartilage located beneath the menisci was 200-500% stiffer than the cartilage that was not covered by the menisci, while the phase lag was almost constant (10+/-2 SD) over the entire tibial plateau. The system was shown to be an accurate and reliable tool for rapidly assessing the dynamic biomechanical properties of articular cartilage, while being small enough to be used arthroscopically.

Modulation of aggrecan and ADAMTS expression in ovine tendinopathy induced by altered strain

OBJECTIVE To evaluate histologic, immunohistochemical, and molecular changes in tendon induced by altered strain in a large-animal model. METHODS A full-thickness partial-width laceration of the infraspinatus tendon was created in 5 sheep, while 5 sham-operated sheep were used as controls. Sheep were killed after 4 weeks, and 4 differentially stressed tendon regions (tensile or near bone attachment from overstressed or stress-deprived halves) were evaluated for histopathology, proteoglycan (PG) accumulation, and characterization of glycosaminoglycans and aggrecan catabolites. Gene expression of matrix components, enzymes, and inhibitors was analyzed by reverse transcriptase-polymerase chain reaction. RESULTS Histopathologic changes were detected in both overstressed and stress-deprived tensile tendon, but only in stress-deprived tendon near bone. In overstressed and stress-deprived tensile tendon, levels of keratan sulfate, chondroitin 4-sulfate, and chondroitin 6-sulfate were increased. In overstressed tensile tendon, levels of ADAMTS-generated aggrecan catabolites were increased. There was increased matrix metalloproteinase 13 (MMP-13) and decreased fibromodulin and decorin expression in all regions. Increased MMP-1, MMP-9, MMP-14, and ADAMTS-1 expression, and decreased type II collagen expression were restricted to stress-deprived tendon. In stress-deprived bone-attachment regions, messenger RNA (mRNA) for aggrecan was decreased, and ADAMTS was increased. In overstressed tensile tendon, aggrecan mRNA was increased, and ADAMTS was decreased. CONCLUSION The distinct molecular changes in adjacent tissue implicate altered strain rather than humoral factors in controlling abnormal tenocyte metabolism, and highlight the importance of regional sampling. Tendon abnormalities induced by increased strain are accompanied by increased aggrecan, decreased ADAMTS, and low PG expression, which may negatively impact the structural integrity of the tissue and predispose to rupture.

Mechanical Destabilization Induced by Controlled Annular Incision of the Intervertebral Disc Dysregulates Metalloproteinase Expression and Induces Disc Degeneration

Study Design. An investigation of mechanical destabilization of the lumbar ovine intervertebral disc (IVD) inducing IVD degeneration (IVDD) as determined by multiparameter outcome measures (magnetic resonance imaging [MRI], IVD composition, biomechanical testing, gene profiling, immunohistochemistry, and immunoblotting). Objective. To assess the effect of IVD mechanical destabilization on matrix protein and metalloproteinase gene expression to investigate the pathophysiological mechanisms of lumbar IVDD. Summary of Background Data. Several earlier studies have used annular transection to induce IVDD in sheep, but none have optimized or validated the most appropriate lesion size. Methods. The annulus fibrosus (AF) incision inducing maximal change in IVD biomechanics was applied to L1–L2, L3–L4, and L5–L6 discs in vivo to compare with a sham procedure at 3 months post operation. IVDs were evaluated by MRI, biomechanics, histopathology, proteoglycan and collagen content, gene expression, and aggrecan proteolysis by Western blotting. Results. Significant changes were observed in lesion (6 × 20 mm2) compared with sham IVDs at 3 months post operation: reduced disc height on MRI; increased neutral zone in biomechanical testing; depleted proteoglycan and collagen content in the nucleus pulposus (NP) and lesion half of the AF but not in the contralateral AF; increased messenger RNA for collagen I and II, aggrecan, versican, perlecan, matrix metalloproteinase (MMP)-1 & 13, and ADAMTS-5, in the lesion-site AF and NP but not in the contralateral AF. ADAMTS-4 messenger RNA was increased in the lesion-site AF but decreased in the NP. Despite an upregulation in MMPs, there was no change in MMP- or ADAMTS-generated aggrecan neoepitopes in any region of the IVD in lesion or sham discs. Conclusion. Lumbar IVDD was reproducibly induced with a 6 × 20 mm2 annular lesion, with focal dysregulation of MMP gene expression, cell cloning in the inner AF, loss of NP aggrecan, and disc height. Loss of aggrecan from the NP was not attributable to increased proteolysis in the interglobular domain by MMPs or ADAMTS.