Margaret Wan Nar Wong

Factors associated with back pain symptoms in pregnancy and the persistence of pain 2 years after pregnancy.

Background.  Factors associated with back pain symptoms in pregnancy and the persistence of pain 2 years after pregnancy.

Triamcinolone suppresses human tenocyte cellular activity and collagen synthesis.

Glucocorticoid injection is widely used in tendon disorders. Despite previous studies on the histologic and biomechanical changes in tendons after glucocorticoid injections, the role of glucocorticoid in tendon rupture still is controversial. It was hypothesized that glucocorticoid has a direct deleterious effect on human tenocytes, suppressing its cellular activity and collagen production. Primary cultures of human tenocytes were obtained from explants of healthy patellar tendon harvested during anterior cruciate ligament reconstructions. The effects on cell viability and cell proliferation were measured by [3-(4,5-demethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and 5-bromo-deoxyuridine incorporations. The effect on collagen synthesis was measured by 3H-proline incorporation assay. Triamcinolone acetonide at 10−9 to 10−4 mol/L decreased human tenocyte viability to 45% to 88% of control in a dose-dependent manner. Cell proliferation was suppressed to 87% ± 8% at all doses. Treatment with 1 μmol/L triamcinolone acetonide reduced the amount of collagen synthesis as measured by 3H-proline incorporation from 40 ± 2 cpm/1000 cells to 27 ± 4 cpm/1000 cells. The suppressed human tenocyte cellular activity and reduced collagen production may lead to disturbed tendon structure and predispose the tendon to subsequent spontaneous rupture.

Effect Of Dexamethasone On Cultured Human Tenocytes And Its Reversibility By Platelet-derived Growth Factor

BACKGROUND Many cases of tendon rupture after glucocorticoid injections have been reported in the literature. Despite previous studies on the histological and biomechanical changes in tendons after glucocorticoid injections, the role of glucocorticoid in causing tendon rupture still remains controversial. The objective of this study was to determine whether glucocorticoid has deleterious effects on the cellular metabolism and collagen production of cultured human tenocytes and the reversibility of these effects by platelet-derived growth factor-BB (PDGFBB). METHODS Primary cultures of human tenocytes obtained from explants of healthy patellar tendon, harvested during anterior cruciate ligament reconstructions, were performed. The effects on cell viability, cell proliferation, and induction of apoptosis were measured by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, 5-bromo-deoxyuridine incorporation, and DNA fragmentation assay, respectively. The effect on collagen synthesis was measured by (3) H-proline incorporation assay. RESULTS The number of viable cells was decreased, in a dose-dependent manner, by the administration of 10 (-9) to 10 (-4) -M dexamethasone. This dose range also suppressed cell proliferation. No apoptotic effect was detected. Treatment with 10 (-6) -M dexamethasone significantly reduced the amount of collagen synthesis. Co-incubation with 10 ng/mL of PDGFBB significantly reversed the effects caused by 10 (-6) -M dexamethasone. CONCLUSIONS Dexamethasone significantly decreased cell viability, suppressed cell proliferation, and reduced collagen synthesis in cultured human tenocytes. The effects were reversed by the simultaneous administration of PDGFBB.

Glucocorticoids suppress proteoglycan production by human tenocytes

Background The role of glucocortiocid injection therapy in spontaneous tendon rupture is controversial. We hypothesized that glucocorticoids suppress proteoglycan production in tendon and studied the in vitro effects of dexamethasone and triamcinolone on proteoglycan production by cultured human tenocytes. Material and methods We obtained primary cultures of human tenocytes from explants of healthy human patellar tendon. The human tenocytes were treated with 1 μM dexamethasone or 1 μM triamcinolone. The amount of proteoglycan production was measured by 35S-sulfate incorporation assay and compared with control cultures. The reversibility of the effect of dexamethasone by co-incubation with 10 ng platelet-derived growth factor (PDGFBB) was also tested. Results Treatment with 1 μM triamcinolone reduced the amount of 35S-sulfate incorporation to 80% of control cultures (p = 0.007), whereas 1 μM dexamethasone reduced it to 72% (p = 0.01). Co-incubation of 10 ng/mL PDGFBB with 1 μM dexamethasone returned the 35S-sulfate incorporation to a level thatwas significantly higher than for dexamethasone treatment alone (108%; p = 0.01). Interpretation Glucocorticoids suppressed proteoglycan production in cultured human tenocytes. The suppression by dexamethasone was reversed by simultaneous addition of PDGFBB. Suppressed proteoglycan production may affect the viscoelastic properties of tendon and increase the risk of spontaneous rupture.   ▪

Expression of transforming growth factor β isoforms and their roles in tendon healing

Transforming growth factor β (TGF‐β) plays active roles in tendon healing. However, the differential effects of TGF‐β isoforms on tendon healing have not been investigated. In cultured tendon fibroblasts, we tested the effects of TGF‐β1, β2, and β3 on the mRNA levels of COL1A1 and COL3A1 by quantitative real‐time polymerase chain reaction. We also investigated the expression of TGF‐β isoforms, TGF‐β receptors, procollagen Type I and Type III in a rat model of tendon healing. We found that TGF‐β3 exhibited the highest potency in stimulating COL1A1 and COL3A1. TGF‐β1 exerted antagonistic effects to TGF‐β2 and β3. All TGF‐β isoforms and procollagen Type I were confined to the edges of the healing tendon at day 28 postinjury. Our results indicated that interaction of TGF‐β isoforms exist in the regulation of collagen synthesis in tendon fibroblasts. Their effects may be further complicated by uneven spatial distribution of TGF‐β and TGF‐β receptors in healing tendons.

Low-Intensity Pulsed Ultrasound on Tendon Healing A Study of the Effect of Treatment Duration and Treatment Initiation

Background Low-intensity pulsed ultrasound has been reported to be effective in promoting tendon healing. However, its optimal time and duration has not yet been determined. Hypothesis Tendons at different stages of healing may respond differently to low-intensity pulsed ultrasound. In the present study, the timing effects of low-intensity pulsed ultrasound on tendon healing were investigated in a rat model with a patellar tendon graft harvest lesion. Study Design Controlled laboratory study. Methods Sixty Sprague-Dawley rats underwent central third patellar tendon donor site harvest. Low-intensity pulsed ultrasound sonication was then delivered to the injured knees at day 1, 14, or 28 after harvest for 2, 4, or 6 weeks. Tendon samples were harvested at day 14, 28, and 42 after lesion for histological examination and mechanical testing. Results A 2-week session of low-intensity pulsed ultrasound applied from day 1 postlesion (D1-2W) significantly improved the ultimate mechanical strength of the healing tendons from 23.1 ± 8.5 MPa to 36.6 ± 9.0 MPa. Low-intensity pulsed ultrasound did not improve healing when it was given at later stages in D15-2W and D29-2W. When low-intensity pulsed ultrasound treatment was extended from 2 weeks (D1-2W) to 4 weeks (D1-4W) or 6 weeks (D1-6W), the beneficial effects on tendon healing became insignificant. Histological examination showed that low-intensity pulsed ultrasound sonication at late healing stages may disturb remodeling with a poor collagen fiber alignment. Conclusion Low-intensity pulsed ultrasound promoted restoration of mechanical strength and collagen alignment in healing tendons only when applied at early healing stages. Clinical Relevance The present findings indicate that low-intensity pulsed ultrasound may be an effective treatment to reduce tendon donor site morbidity.

Modified flexor hallucis longus transfer for Achilles insertional rupture in elderly patients.

Elderly patients with symptomatic Achilles tendinopathy who develop insertional ruptures develop are at risk of persistent pain and poor functional outcome. Extensive debridement of the tendinopathy creates a defect that adds to the difficulty of Achilles insertional rupture repair. Complete excision of the tendinopathy segment was proposed to minimize persistent pain. Reconstruction of the defect using modified flexor hallucis longus transfer might better restore Achilles function. Five patients older than 50 years (mean age, 58.8 years) who had symptomatic Achilles tendinopathy and subsequently had insertional ruptures were treated. The outcome was assessed at an average of 28.8 months after the reconstruction. There was good pain relief. All patients were able to do single-leg stance. Cybex isokinetic testing showed plantar flexion peak torque deficits of 10.9% and 3.9% when tested at 60°/second and 120°/second, respectively. The Functional Ambulation Performance score indicated a near normal gait pattern. The American Orthopaedic Foot and Ankle Society hindfoot score improved from 64.4 to 94.4. There was no major surgical complication and no rerupture. Excision of Achilles tendinopathy segment followed by modified flexor hallucis longus transfer can achieve good pain relief and functional recovery in elderly patients with symptomatic Achilles tendinopathy who have Achilles insertional ruptures develop. Level of Evidence: Therapeutic study, Level IV (case series—no, or historical control group)

Relationship between bone mineral density changes in pregnancy and maternal and pregnancy characteristics: a longitudinal study

Objective.  The study aims to verify whether a progressive fall in bone mineral density (BMD) values can be demonstrated using quantitative ultrasound measurements of the os calcis. The BMD change during the pregnancy was then correlated with other maternal and pregnancy characteristics to identify any high‐risk factors for bone loss in pregnancy.

The effect of glucocorticoids on tendon cell viability in human tendon explants

Background and purpose Previous studies on the culture of human tenocytes have shown that dexamethasone and triamcino-lone reduce cell viability, suppress cell proliferation, and reduce collagen synthesis. However, such cell cultures lack the extracellular matrix and three-dimensional structure of normal tendons, which affects their response to stimuli. We established a human tendon explant culture system and tested the effects of dexamethasone and triamcinolone on cell viability. Methods Primary human tendon explant cultures were prepared from healthy hamstring tendons. Tendon strips were harvested from hamstring tendons and cultured in 24-well plates in Dulbecco’s modification of Eagle’s Medium (DMEM) supplemented with 2% fetal calf serum. The tendon explants were treated with 0 μM (control), 10 μM, or 100 μM dexamethasone sodium phosphate or 0 μM (control), 10 μM, or 100 μM triamcinolone acetonide in DMEM for 96 h. Cell viability was measured by Alamar blue assay before and after glucocorticoid treatment. Results Incubation with 10 μM and 100 μM dexamethasone reduced cell viability in human tendon explants by 35% and 45%, respectively, as compared to a 6% increase in the controls (p = 0.01, mixed-effects ANOVA). Triamcinolone at 10 μM and 100 μM reduced cell viability by 33% and 36%, respectively, as compared to a 9% increase in the controls (p = 0.07, mixed-effects ANOVA). Interpretation Human tendon explant cultures can be used to study the effects of glucocorticoids on human tendon. Dexamethasone and triamcinolone suppress the cell viability of human tendon in its natural 3-dimensional environment with matrix anchorage. Human tendon explant cultures provide a species-specific model for further investigation of the effects of glucocorticoids on the metabolism of the extracellular matrix of human tendon, and on its mechanical properties.

Healing of bone-tendon junction in a bone trough: a goat partial patellectomy model.

Bone-tendon junction healing in a bone trough was investigated in a goat partial patellectomy model. Histologic evaluation and biomechanical tests were done at 6, 12, and 24 weeks. Irregular fibrous tissue seen at the healing bone-tendon junction at 6 weeks gradually assumed longitudinal alignment and remodeled toward a direct bone-tendon junction. Type III collagen deposition was diffuse at 6 weeks, but became localized to the healing interface at 12 weeks. Thickness of newly formed bone increased progressively with time. Bridging collagen fibers were formed at the junction, with fibrochondrocytic cells and a basophilic tidemark detected at 24 weeks. The trabecular line remained discontinuous and there was no safranin O uptake. Most specimens failed at the junctions under tensile loads. The ultimate failure stress increased from 4.78 ± 0.50 N/mm2 at 6 weeks to 7.99 ± 0.33 N/mm2 at 24 weeks (mean ± standard error of the mean), only reaching 15% of normal. Cartilage from the articular cut surface extended into the healing interface, later forming an area of fibrocartilage with densely packed collagen fibers aligned along the direction of force, containing proteoglycans. Cartilage may enhance restoration of a transition zone in bone-tendon junction healing. The sequence of events outlined formed a basis to guide clinical practice regarding bone-tendon junction reattachment.