Differential inhibition of fracture healing by non-selective and cyclooxygenase-2 selective non-steroidal anti-inflammatory drugs

Negative effect of parecoxib on bone mineral during fracture healing in rats

BACKGROUND AND PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) are conventional cyclooxygen-ase (cox) inhibitors commonly used in musculoskeletal trauma to reduce the inflammatory response and pain, but they also seem to affect bone metabolism. Parecoxib is a cox inhibitor that selectively inhibits cox-2. Through their selective mechanism of action, these newer drugs are supposed to reduce the gastrointestinal side effects of conventional cox inhibitors. The effects on bone metabolism and healing have, however, not been fully elucidated. Thus, there are reasons for concern regarding the potential negative effects of these drugs on bone metabolism and bone repair. We investigated the effects of short-term administration of parecoxib on bone mineral formation and bone healing in rats.

ANIMALS AND METHODS

26 female Wistar rats were given parecoxib intraperitoneally for 7 days after a closed tibial fracture that was stabilized with an intra-medullary nail, and 26 animals were given saline. At 2, 3, and 6 weeks after surgery bone mineral density (BMD) at the fracture site was measured using dualenergy X-ray absorptiometry (DEXA). 6 weeks after the fracture, 14 rats from the parecoxib group and 16 rats from the placebo group were killed for mechanical testing, and the rest of the animals were killed for tissue analysis. The healing fractures and the intact contralateral tibias were mechanically tested by three-point cantilever bending.

RESULTS

The BMD at the fracture site was calculated as the average of the results after 2,3, and 6 weeks. Mean BMD was lower in the parecoxib group, 0.23 (SD 0.06) g/ cm2, than in the control group, 0.27 (SD 0.05) g/cm2 (p = 0.01). There were no statistically significant differences in mechanical properties of the healing fractures after 6 weeks. However, the study may have lacked sufficient statistical power to determine whether a negative effect on healing had occurred.

INTERPRETATION

No mechanical differences were detected between the control and treatment groups after 6 weeks, but they may have been present earlier in the fracture healing process. Our findings do, however, indicate that parecoxib given postoperatively for a week has a negative effect on mineralization during the early phase of fracture healing.

Pharmacological agents and impairment of fracture healing: what is the evidence?

Bone healing is an extremely complex process which depends on the coordinated action of several cell lineages on a cascade of biological events, and has always been a major medical concern. The use of several drugs such as corticosteroids, chemotherapeutic agents, non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, anticoagulants and drugs which reduce osteoclastic activity have been shown to affect bone healing. This review article presents our current understanding on this topic, focusing on data illustrating the effect of these drugs on fracture healing and bone regeneration.

Effect of meloxicam and diclofenac sodium on peri-implant bone healing in rats

BACKGROUND

This study evaluated the effects of diclofenac sodium and meloxicam on peri-implant bone healing.

METHODS

Thirty male rats were divided into three groups: the control group (CG) received no drug; the diclofenac sodium group (DSG) received 1.07 mg/kg twice a day for 5 days; and the meloxicam group (MG) received 0.2 mg/kg daily for 5 days. A screw-shaped titanium implant was placed in the tibia. Fluorochromes, oxytetracycline (OxT), calcein (CA), and alizarin (AL), were injected at 7, 14, and 21 days, respectively, after implantation, and the animals were sacrificed 28 days after implant placement. The percentages of OxT-, CA-, and AL-labeled bone as well as the percentages of bone-to-implant contact (BIC), cortical bone area (CBA), and trabecular bone area (TBA) within the implant threads were evaluated.

RESULTS

Bone healing was delayed in the DSG during the first 14 days after implant placement (OxT-labeled bone: DSG: 5.3% +/- 7.3% versus CG: 13.2% +/- 9.8%, P = 0.002, and versus MG:14.4% +/- 13.1%, P = 0.05). The percentages of BIC (DSG: 49.6% +/- 21.9%; MG: 67.1% +/- 22.8%; and CG: 68.1% +/- 22.8%) and CBA (DSG: 63.7% +/- 21.2%; MG: 82.7% +/- 12.4%; CG: 84.9% +/- 10.6%) were lower in the DSG compared to the MG and CG (P <0.001). The percentage of TBA was significantly greater in the DSG compared to the MG and CG (DSG: 36.3% +/- 21.2% versus MG: 17.3% +/- 12.7% and versus CG: 15.1% +/- 10.6%; P <0.001).

CONCLUSION

Diclofenac sodium seemed to delay peri-implant bone healing and to decrease BIC, whereas meloxicam had no negative effect on peri-implant bone healing.

Update on the role of nonsteroidal anti-inflammatory drugs and coxibs in the management of acute pain

PURPOSE OF REVIEW

Although NSAIDs have been shown to reduce postoperative analgesics, their ability to reduce opioid-related adverse effects and improve functional outcomes is questioned. Further, perioperative NSAID use may contribute to cardiovascular toxicity and impaired bone healing. This review highlights recent advances in our understanding of the role perioperative NSAIDs have on modulating nociception, their benefits when utilized as components of a multimodal analgesic regimen, and potential deleterious cardiovascular and osteogenic effects.

RECENT FINDINGS

Recent research indicates that, in addition to peripheral blockade of prostaglandin synthesis, central inhibition of cyclooxygenase-2 may play an important role in modulating nociception. Although nonspecific NSAIDs provide analgesic efficacy similar to coxibs, their use has been limited in the perioperative setting because of platelet dysfunction and gastrointestinal toxicity. Coxibs may be a safer alternative in that setting. Both coxibs and traditional NSAIDs may contribute to a dose-dependent increase in cardiovascular toxicity and impaired osteogenesis. When used short term at the lowest effective dose, however, NSAIDs may provide for analgesic benefit without significant toxicity.

SUMMARY

When utilized as a component of a multimodal analgesic regimen for acute pain, short-term NSAID administration reduces opioid-related side effects and may contribute to improved functional outcomes without significant adverse effects.

Inhibition of fracture healing

This paper reviews the current literature concerning the main clinical factors which can impair the healing of fractures and makes recommendations on avoiding or minimising these in order to optimise the outcome for patients. The clinical implications are described.

Effects of a monoclonal antibody raised against nerve growth factor on skeletal pain and bone healing after fracture of the C57BL/6J mouse femur

A closed femur fracture pain model was developed in the C57BL/6J mouse. One day after fracture, a monoclonal antibody raised against nerve growth factor (anti-NGF) was delivered intraperitoneally and resulted in a reduction in fracture pain-related behaviors of approximately 50%. Anti-NGF therapy did not interfere with bone healing as assessed by mechanical testing and histomorphometric analysis.

INTRODUCTION

Current therapies to treat skeletal fracture pain are limited. This is because of the side effect profile of available analgesics and the scarcity of animal models that can be used to understand the mechanisms that drive this pain. Whereas previous studies have shown that mineralized bone, marrow, and periosteum are innervated by sensory and sympathetic fibers, it is not understood how skeletal pain is generated and maintained even in common conditions such as osteoarthritis, low back pain, or fracture.

MATERIALS AND METHODS

In this study, we characterized the pain-related behaviors after a closed femur fracture in the C57BL/6J mouse. Additionally, we assessed the effect of a monoclonal antibody that binds to and sequesters nerve growth factor (anti-NGF) on pain-related behaviors and bone healing (mechanical properties and histomorphometric analysis) after fracture.

RESULTS

Administration of anti-NGF therapy (10 mg/kg, days 1, 6, and 11 after fracture) resulted in a reduction of fracture pain-related behaviors of approximately 50%. Attenuation of fracture pain was evident as early as 24 h after the initial dosing and remained efficacious throughout the course of fracture pain. Anti-NGF therapy did not modify biomechanical properties of the femur or histomorphometric indices of bone healing.

CONCLUSIONS

These findings suggest that therapies that target NGF or its cognate receptor(s) may be effective in attenuating nonmalignant fracture pain without interfering with bone healing.

Non-steroidal anti-inflammatory drugs, cyclooxygenase-2 and the bone healing process

Traditional non-steroidal anti-inflammatory drugs (NSAID) and selective cyclooxygenase-2 (COX-2) inhibitors are widely used in the treatment of pain, including bone fracture pain and orthopaedic post-operative pain. The gastrointestinal and cardiovascular adverse effects of NSAIDs are acknowledged, but their effects on bone are less widely known. Prostaglandins play an important role in the regulation of osteoblast and osteoclast functions, and inhibition of prostaglandin production retards bone formation. Therefore, NSAIDs could be expected to have significant consequences in divergent clinical situations where bone formation or remodelling is a contributing factor. The present survey reviews current experimental and clinical evidence related to two of those conditions (i.e. on ectopic bone formation and on bone fracture healing). NSAIDs are used clinically to prevent ectopic bone formation (also known as heterotopic ossification) (e.g. after total hip arthroplasty or trauma). The efficacy of NSAIDs in the avoidance of heterotopic ossification has been documented in controlled clinical trials, but the inherent risks (e.g. on healing processes and on loosening of prostheses) need further studies. At the same time, NSAIDs are widely used in the treatment of fracture pain, and their inhibitory effects on the ongoing bone healing process have raised concerns. Results of fracture healing studies in animals treated with NSAIDs or in mice lacking COX-2 gene show that inhibition or deficiency of COX-2 impairs the bone healing process. The limited clinical data also support the assumption that inhibition of COX-2 by non-selective or COX-2-selective NSAIDs delays fracture healing. However, the clinical significance of the effect in various patient groups needs to be carefully assessed and further investigations are needed to characterize the patients at the highest risk for NSAID-induced delayed fracture healing and its complications. In the meantime, use of NSAIDs in fracture patients should be cautious, keeping in mind the benefits of pain relief and inhibition of ectopic bone formation on one hand, and the risks of non-union and retarded union on the other hand.

Inhibition of cyclooxygenase-2 down-regulates osteoclast and osteoblast differentiation and favours adipocyte formation in vitro

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenases (COX) and are widely used for post-trauma musculoskeletal analgesia. In animal models, NSAIDs have been reported to delay fracture healing and cause non-union, possibly due to the drug-induced inhibition of osteoblast recruitment and differentiation. To further investigate the cellular effects of these drugs in the context of bone healing, we examined the effects of COX-1 inhibitor indomethacin and COX-2 inhibitors, parecoxib and NS398 on osteoclast and osteoblast differentiation and activity in vitro. We discovered that all tested COX-inhibitors significantly inhibited osteoclast differentiation, by 93%, 94% and 74% of control for 100 microM indomethacin, 100 microM parecoxib and 3 microM NS398, respectively. Furthermore, inhibition of COX-2 reduced also the resorption activity of mature osteoclasts. All tested COX-inhibitors also significantly inhibited osteoblast differentiation from human mesenchymal stem cells. Simultaneously, the number of adipocytes was significantly increased. The adipocyte covered areas in the cultures with 1 microM indomethacin, 1 microM parecoxib and 3 microM NS398 were 9%, 29% and 24%, respectively, as compared with 6% in the control group. This data suggests that COX-2 inhibition disturbs bone remodelling by inhibiting osteoclast differentiation and diverting stem cell differentiation towards adipocyte lineage instead of osteoblast lineage. In conclusion, our results further suggest cautious use of COX-2 inhibitors after osseous trauma.

The effects of the short-term administration of low therapeutic doses of anti-COX-2 agents on the healing of fractures

We have evaluated the effect of the short-term administration of low therapeutic doses of modern COX-2 inhibitors on the healing of fractures.

A total of 40 adult male New Zealand rabbits were divided into five groups. A mid-diaphyseal osteotomy of the right ulna was performed and either normal saline, prednisolone, indometacin, meloxicam or rofecoxib was administered for five days. Radiological, biomechanical and histomorphometric evaluation was performed at six weeks.

In the group in which the highly selective anti-COX-2 agent, rofecoxib, was used the incidence of radiologically-incomplete union was similar to that in the control group. All the biomechanical parameters were statistically significantly lower in both the prednisolone and indometacin (p = 0.01) and in the meloxicam (p = 0.04) groups compared with the control group. Only the fracture load values were found to be statistically significantly lower (p = 0.05) in the rofecoxib group. Histomorphometric parameters were adversely affected in all groups with the specimens of the rofecoxib group showing the least negative effect.

Our findings indicated that the short-term administration of low therapeutic doses of a highly selective COX-2 inhibitor had a minor negative effect on bone healing.

Nerve growth factor sequestering therapy attenuates non-malignant skeletal pain following fracture

Current therapies to treat skeletal fracture pain are extremely limited. Some non-steroidal anti-inflammatory drugs have been shown to inhibit bone healing and opiates induce cognitive dysfunction and respiratory depression which are especially problematic in the elderly suffering from osteoporotic fractures. In the present report, we developed a closed femur fracture pain model in the mouse where skeletal pain behaviors such as flinching and guarding of the fractured limb are reversed by 10mg/kg morphine. Using this model we showed that the administration of a monoclonal antibody against nerve growth factor (anti-NGF) reduced fracture-induced pain-related behaviors by over 50%. Treatment with anti-NGF reduced c-Fos and dynorphin up-regulation in the spinal cord at day 2 post-fracture. However, anti-NGF treatment did not reduce p-ERK and c-Fos expression at 20 and 90 min, respectively, following fracture. This suggests NGF is involved in maintenance but not the acute generation of fracture pain. Anti-NGF therapy did not inhibit bone healing as measured by callus formation, bridging of the fracture site or mechanical strength of the bone. As the anti-NGF antibody does not appreciably cross the blood-brain barrier, the present data suggest that the anti-hyperalgesic action of anti-NGF therapy results from blockade of activation and/or sensitization of the CGRP/trkA positive fibers that normally constitute the majority of sensory fibers that innervate the bone. These results demonstrate that NGF plays a significant role in driving fracture pain and that NGF sequestering therapies may be efficacious in attenuating this pain.

The effects of medications on bone

Medications taken for the treatment of arthritis and psychotropic and epileptic disorders, as well as anticoagulants, antacids, bisphosphonates, corticosteroids, and antineoplastic drugs, can profoundly affect bone metabolism. In some scenarios (eg, osteoporosis), these effects are intended; in others (eg, rickets, osteomalacia secondary to antiepileptic drugs), potentially adverse side effects of medications on bone may occur. Nonsteroidal anti-inflammatory drugs appear to delay fracture healing and bone ingrowth, although these effects are reversible. Disease-modifying antirheumatic drugs do not appear to affect bone metabolism adversely when taken in the low dosages currently prescribed. Bisphosphonates are useful in restoring bone mass in cases of postmenopausal osteoporosis, glucocorticoid-induced osteoporosis, Paget's disease, and neoplastic conditions with bone loss and hypercalcemia. Corticosteroids and cancer chemotherapeutic agents generally affect bone adversely and increase fracture risk.

Cyclooxygenase-2 gene disruption promotes proliferation of murine calvarial osteoblasts in vitro

Cyclooxygenase-2 (COX-2) is highly expressed in osteoblasts, and COX-2 produced prostaglandins (PGs) can increase osteoblastic differentiation in vitro. The goal of this study was to examine effects of COX-2 expression on calvarial osteoblastic proliferation and apoptosis. Primary osteoblasts (POBs) were cultured from calvariae of COX-2 wild-type (WT) and knockout (KO) mice. POB proliferation was evaluated by (3)H-thymidine incorporation and analysis of cell replication and cell cycle distribution by flow cytometry. POB apoptosis was evaluated by annexin and PI staining on flow cytometry. As expected, PGE(2) production and alkaline phosphatase (ALP) activity were increased in WT cultures compared to KO cultures. In contrast, cell numbers were decreased in WT compared to KO cells by day 4 of culture. Proliferation, measured on days 3-7 of culture, was 2-fold greater in KO than in WT POBs and associated with decreased Go/G1 and increased S cell cycle distribution. There was no significant effect of COX-2 genotype on apoptosis under basal culture conditions on day 5 of culture. Cell growth was decreased in KO POBs by the addition of PGE(2) or a protein kinase A agonist and increased in WT POBs by the addition of NS398, a selective COX-2 inhibitor. In contrast, differentiation and cell growth in marrow stromal cell (MSC) cultures, evaluated by ALP and crystal violet staining respectively, were increased in MSCs from WT mice compared to MSCs from KO mice, and exogenous PGE(2) increased cell growth in KO MSC cultures. We conclude that PGs secondary to COX-2 expression decrease osteoblastic proliferation in cultured calvarial cells but increase growth of osteoblastic precursors in MSC cultures.

Preliminary study on the effect of parenteral naloxone, alone and in association with calcium gluconate, on bone healing in an ovine "drill hole" model system

Background

Several diseases affect bone healing and physiology. Many drugs that are commonly used in orthopaedics as "analgesics" or anti-inflammatory agents impair bone healing. Stressful conditions are associated with decreased serum osteocalcin concentration. High endorphin levels alter calcium metabolism, blocking the membrane channels by which calcium normally enters cells. The consequent decrease of intracellular calcium impairs the activities of calcium-related enzymes. Naloxone is a pure opioid antagonist. Morphine-induced osteocalcin inhibition was abolished when osteoblasts were incubated with naloxone. Naloxone restored the altered cellular and tissue physiology by removing β-endorphins from specific receptors. However, this is only possible if the circulating Ca concentration is adequate. The aim of the present study was to evaluate the efficacy of parenteral naloxone administration in inducing fast mineralization and callus remodelling in a group of sheep with a standardised bone lesion.

Methods

Twenty ewes were randomly assigned to 4 treatment groups. Group A acted as control, group B received a solution of calcium gluconate, group C a solution of naloxone, and group D a solution of calcium gluconate and naloxone. A transverse hole was drilled in the left metacarpus, including both cortices, then parenteral treatment was administered intramuscularly, daily for four weeks. Healing was evaluated by weekly radiographic examination for eight weeks. For quantitative evaluation, the ratio of the radiographic bone density between the drill area and the adjacent cortical bone was calculated. After eight weeks the sheep were slaughtered and a sample of bone was collected for histopathology

Results

Group D showed a higher radiographic ratio than the other groups. Sheep not treated with naloxone showed a persistently lower ratio in the lateral than the medial cortex (P < 0.01). Histopathology of bone samples showed more caverns and fewer osteoblasts in group D than in the other groups (P ≤ 0.001).

Conclusion

A low-dose parenteral regimen of naloxone enhances mineralization and remodelling of the callus in healing cortical defects in sheep, especially if associated with calcium gluconate.

Diminished bone formation during diabetic fracture healing is related to the premature resorption of cartilage associated with increased osteoclast activity

Histological and molecular analysis of fracture healing in normal and diabetic animals showed significantly enhanced removal of cartilage in diabetic animals. Increased cartilage turnover was associated with elevated osteoclast numbers, a higher expression of genes that promote osteoclastogenesis, and diminished primary bone formation.

INTRODUCTION

Diminished bone formation, an increased incidence of nonunions, and delayed fracture healing have been observed in animal models and in patients with diabetes. Fracture healing is characterized by the formation of a stabilizing callus in which cartilage is formed and then resorbed and replaced by bone. To gain insight into how diabetes affects fracture healing, studies were carried out focusing on the impact of diabetes on the transition from cartilage to bone.

MATERIALS AND METHODS

A low-dose treatment protocol of streptozotocin in CD-1 mice was used to induce a type 1 diabetic condition. After mice were hyperglycemic for 3 weeks, controlled closed simple transverse fractures of the tibia were induced and fixed by intramedullary pins. Histomorphometric analysis of the tibias obtained 12, 16, and 22 days after fracture was performed across the fracture callus at 0.5 mm proximal and distal increments using computer-assisted image analysis. Another group of 16-day samples were examined by microCT. RNA was isolated from a separate set of animals, and the expression of genes that reflect the formation and removal of cartilage and bone was measured by real-time PCR.

RESULTS

Molecular analysis of collagen types II and X mRNA expression showed that cartilage formation was the same during the initial period of callus formation. Histomorphometric analysis of day 12 fracture calluses showed that callus size and cartilage area were also similar in normoglycemic and diabetic mice. In contrast, on day 16, callus size, cartilage tissue, and new bone area were 2.0-, 4.4-, and 1.5-fold larger, respectively, in the normoglycemic compared with the diabetic group (p < 0.05). Analysis of microCT images indicated that the bone volume in the normoglycemic animals was 38% larger than in diabetic animals. There were 78% more osteoclasts in the diabetic group compared with the normoglycemic group (p < 0.05) on day 16, consistent with the reduction in cartilage. Real-time PCR showed significantly elevated levels of mRNA expression for TNF-alpha, macrophage-colony stimulating factor, RANKL, and vascular endothelial growth factor-A in the diabetic group. Similarly, the mRNA encoding ADAMTS 4 and 5, major aggrecanases that degrade cartilage, was also elevated in diabetic animals.

CONCLUSIONS

These results suggest that impaired fracture healing in diabetes is characterized by increased rates of cartilage resorption. This premature loss of cartilage leads to a reduction in callus size and contributes to decreased bone formation and mechanical strength frequently reported in diabetic fracture healing.

Dose and time-dependent effects of cyclooxygenase-2 inhibition on fracture-healing

BACKGROUND

Fracture-healing is impaired in mice lacking a functional cyclooxygenase-2 (COX-2) gene or in rats continuously treated with COX-2 inhibitors. These observations indicate that COX-2 is a critical regulator of fracture repair. Nonsteroidal anti-inflammatory drugs are commonly used to treat pain associated with musculoskeletal trauma and disease. Nonsteroidal anti-inflammatory drugs inhibit COX-2 function and in so doing can impair fracture-healing. The goal of the present study was to determine how variations in nonsteroidal anti-inflammatory drug therapy ultimately affect fracture-healing.

METHODS

Closed femoral fractures were made in female Sprague-Dawley rats. The rats were treated with different doses of celecoxib (a COX-2-selective nonsteroidal anti-inflammatory drug) or were treated for different periods before or after fracture with celecoxib. Eight weeks after the fracture, healing was assessed with radiography and destructive torsional mechanical testing. The effect of celecoxib treatment on fracture callus prostaglandin E2 and F(2alpha) levels was determined as a measure of cyclooxygenase activity.

RESULTS

Celecoxib doses as small as 2 mg/kg/day reduced fracture callus mechanical properties and caused a significant increase in the proportion of nonunions. Similarly, treatment with celecoxib at a dose of 4 mg/kg/day for just five days reduced fracture callus mechanical properties and significantly increased the proportion of nonunions. Conversely, celecoxib therapy prior to fracture or initiated fourteen days after fracture did not significantly increase the proportion of nonunions. Celecoxib treatment at a dose of 4 mg/kg/day reduced fracture callus prostaglandin E2 and F(2alpha) levels by >60%.

CONCLUSIONS

COX-2-selective nonsteroidal anti-inflammatory drug therapy during the early stages of fracture repair significantly reduced fracture callus mechanical properties at later stages of healing and increased the proportion of nonunions in this animal model.

Cyclooxygenase-2 inhibition delays the attainment of peak woven bone formation following four-point bending in the rat

Fracture healing is retarded in the presence of cyclooxygenase-2 (COX-2) inhibitors, demonstrating an important role of COX-2 in trauma-induced woven bone adaptation. The aim of this experiment was to determine the influence of COX-2 inhibition on the remodeling and consolidation of nontraumatic woven bone produced by mechanical loading. A periosteal woven bone callus was initiated in the right tibia of female Wistar rats following a single bout of four-point bending, applied as a haversine wave for 300 cycles at a frequency of 2 Hz and a magnitude of 65 N. Daily injections of vehicle (VEH, polyethylene glycol) or the COX-2 inhibitor 5,5-dimethyl-3-3(3 fluorophenyl)-4-(4-methylsulfonal)phenyl-2(5H)-furanone (DFU, 2.0 mg . kg(-1) and 0.02 mg . kg(-1) i.p.), commenced 7 days postloading, and tibiae were examined 2, 3, 4, and 5 weeks postloading. Tibiae were dissected, embedded in polymethylmethacrylate, and sectioned for histomorphometric analysis of periosteal woven bone. No significant difference in peak woven bone area was observed between DFU-treated and VEH rats. However, treatment with DFU resulted in a temporal defect in woven bone formation, where the achievement of peak woven bone area was delayed by 1 week. Woven bone remodeling was observed in DFU-treated rats at 21 days postloading, demonstrating that remodeling of the periosteal callus is not prevented in the presence of a COX-2 inhibitor in the rat. We conclude that COX-2 inhibition does not significantly disrupt the mechanism of woven bone remodeling but alters its timing.

Effects of continuous oral administration of phenylbutazone on biomarkers of cartilage and bone metabolism in horses

OBJECTIVE

To evaluate the effects of continuous oral administration of phenylbutazone on serum and synovial fluid biomarkers of skeletal matrix metabolism in horses.

ANIMALS

11 adult female horses without clinical or radiographic evidence of joint disease.

PROCEDURES

Horses were randomly assigned to control or treatment groups. Phenylbutazone was administered orally twice daily at a dose of 4.4 mg/kg for 3 days to the treatment group and subsequently at a dose of 2.2 mg/kg for 7 days. Serum and radiocarpal synovial fluid samples were obtained at baseline and thereafter at regular intervals for 4 weeks. Biomarkers of cartilage aggrecan synthesis (chondroitin sulfate 846) and type II collagen synthesis (procollagen type II C-propeptide) and degradation (collagen type II cleavage) were assayed. Biomarkers of bone synthesis (osteocalcin) and resorption (C-terminal telopeptide of type I collagen) were also measured.

RESULTS

No significant differences were found between control and treatment groups or temporally for the biomarkers chondroitin sulfate 846, procollagen type II C-propeptide, collagen type II cleavage, and C-terminal telopeptide of type I collagen in serum or synovial fluid. A significant increase in osteocalcin concentration occurred in synovial fluid during treatment in the treated group. No treatment effect was detected for serum osteocalcin concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that continuous phenylbutazone administration at recommended doses altered some biomarkers in healthy equine joints after short periods of administration. Increased osteocalcin concentration may indicate an undetermined anabolic effect of phenylbutazone administration on periarticular bone or transient induction of osteogenesis in articular chondrocytes or a mesenchymal subpopulation of synoviocytes.

Effects of local infusion of OP-1 on particle-induced and NSAID-induced inhibition of bone ingrowth in vivo

Excessive polyethylene wear particles from joint replacements may lead to periprosthetic osteolysis and loosening. Nonsteroidal anti-inflammatory drugs (NSAIDs) decrease fracture healing and bone ingrowth. We hypothesized that continuous local infusion of OP-1 (BMP-7) would increase local bone formation in the presence of two different adverse stimuli, polyethylene particles, and an oral NSAID. The Drug Test Chamber (DTC) was implanted in the proximal tibia of mature rabbits. The tissue growing into the chamber was exposed to OP-1 solution (110 ng/day), which was infused via an osmotic pump. Infusion of OP-1 alone for 6 weeks enhanced local bone formation in the chamber by 80% (p < 0.05) over infusion of carrier alone. In the presence of polyethylene particles, infusion of OP-1 increased local bone formation by 38% (p < 0.05) over treatment with particles and carrier. Oral administration of NSAID reduced local bone formation by 58% (p < 0.05); this suppressive effect caused by NSAIDS was completely reversed by the infusion of OP-1 (p < 0.05). These findings underline a potential role for local treatment with OP-1 to increase bone formation in the presence of potentially adverse stimuli such as polyethylene wear particles or NSAID use.

Efeito dos anti-inflamatórios não-esteroidais convencionais e seletivos para COX-2 sobre o reparo ósseo

Na presente revisão de literatura foram relacionados trabalhos experimentais e clínicos dos últimos 15 anos referentes aos efeitos dos antiinflamatórios não-esteroidais (AINEs) convencionais e seletivos para COX-2 sobre a formação óssea reparacional. A maioria dos trabalhos mostra que os AINEs convencionais podem atrasar o reparo de fratura de ossos longos e a fusão espinhal, em animais, e interferir negativamente com a taxa de fusão espinhal, em humanos. Apesar da importância comprovada da prostaglandina E2, sintetizada por osteoblastos sob estímulo da enzima ciclooxigenase-2 (COX-2), no controle da formação óssea, os resultados experimentais acerca dos prováveis efeitos inibitórios dos AINEs seletivos sobre o reparo ósseo além de raros são ainda controversos e não há comprovação de que eles interferem com a neoformação óssea reparacional em humanos.

Ischemia leads to delayed union during fracture healing: a mouse model

Vascular damage accompanying skeletal injury leads to an ischemic environment, and in clinical settings the extent of vascular damage is directly correlated with failure of skeletal repair. However, the exact mechanism(s) underlying ischemia-related defects in bone healing are not well understood. To better understand the mechanism and to facilitate development of novel interventions to treat ischemic fractures, a mouse model of long bone fracture healing in an ischemic environment was created. Ischemia was induced by femoral artery resection prior to tibia fracture. Fractures were left unstabilized or were stabilized with custom-designed external fixators. Animals with intact femoral vessels served as controls. Tissues from non-stabilized fractures were analyzed at various times from 3 to 28 days after injury (n = 5/time point). Femoral artery resection severely impaired blood supply to the fractured limbs, and perfusion to the fracture sites did not recover until 14 days post-injury. Ischemia significantly decreased the callus size (p < 0.05), and decreased bone (p < 0.05) and cartilage (p < 0.05) matrix production during healing of non-stabilized fracture. The decreased formation of skeletal tissues in ischemic limbs was accompanied by decreased cell proliferation and increased apoptosis at early time points, and increased fibrous and fatty tissues adjacent to the fracture site during the third and fourth week after injury. These alterations led to a delayed-union. Complete fracture healing was not achieved in the majority (day 21 = 4/5; day 28 = 5/5) of ischemic animals, while all control mice (n = 5/5) had evidence of bony bridging by day 21. The ratio of cartilage to bone was similar in ischemic and control limbs at days 7 and 10 in non-stabilized fractures. In stabilized fractures, which healed through direct bone formation in the nonischemic controls, ischemia decreased the amount of bone formation at days 10 and 14 (n = 5/time point) but did not induce cartilage formation. These data reveal that an ischemic insult in the hind limb prior to fracture leads to a delayed union or a nonunion, but does not favor formation of cartilage over bone. This model will be useful for testing novel therapeutic regimens to stimulate fracture healing.

Selective and nonselective cyclooxygenase-2 inhibitors and experimental fracture-healing. Reversibility of effects after short-term treatment

BACKGROUND

Cyclooxygenase-2-specific anti-inflammatory drugs (coxibs) and nonspecific nonsteroidal anti-inflammatory drugs have been shown to inhibit experimental fracture-healing. The present study tested the hypothesis that these effects are reversible after short-term treatment.

METHODS

With use of a standard model of fracture-healing, identical ED50 dosages of either a nonsteroidal anti-inflammatory drug (ketorolac), a coxib (valdecoxib), or vehicle (control) were orally administered to rats for either seven or twenty-one days and fracture-healing was assessed with biomechanical, histological, and biochemical analyses.

RESULTS

When healing was assessed at twenty-one days, the seven-day treatment produced only a trend for a higher rate of nonunion in valdecoxib and ketorolac-treated animals as compared with controls. No differences were observed at thirty-five days. The twenty-one-day treatment produced significantly more nonunions in valdecoxib-treated animals as compared with either ketorolac-treated or control animals (p < 0.05), but these differences disappeared by thirty-five days. The dose-specific inhibition of these drugs on prostaglandin E2 levels and the reversibility of the effects after drug withdrawal were assessed in fracture calluses and showed that ketorolac treatment led to twofold to threefold lower levels of prostaglandin E2 than did valdecoxib. Withdrawal of either drug after six days led to a twofold rebound in these levels by fourteen days. Histological analysis showed delayed remodeling of calcified cartilage and reduced bone formation in association with valdecoxib treatment.

CONCLUSIONS

Cyclooxygenase-2-specific drugs inhibit fracture-healing more than nonspecific nonsteroidal anti-inflammatory drugs, and the magnitude of the effect is related to the duration of treatment. However, after the discontinuation of treatment, prostaglandin E2 levels are gradually restored and the regain of strength returns to levels similar to control.

The role of COX-2 inhibitors in the treatment of postoperative pain

Postoperative pain requires treatment not only to provide comfort to patients but also to improve postoperative outcome. Anti-inflammatory compounds are an important component of multimodal analgesia in the postoperative period. The newer cyclooxygenase (COX)-2 inhibitors are as effective as classical nonsteroidal anti-inflammatory drugs (NSAIDs) in this setting. However, COX-2 inhibitors offer a number of advantages over NSAIDs when used to treat postoperative pain. These include a reduced incidence of gastrointestinal ulceration and no inhibitory effect on platelet function and thereby a reduced risk of blood loss. Other benefits are less impairment of bone healing and no induction of bronchospasm in patients with aspirin-sensitive asthma. Increased cardiovascular thromboembolic events by COX-2 inhibitors have been reported after coronary artery bypass graft surgery only, but in general, surgery studies the incidence of such complications was comparable to placebo. Overall, COX-2 inhibitors offer a number of advantages over classical NSAIDs in the postoperative pain setting, but require the same caution with regard to renal effects.

Nonsteroidal anti-inflammatory drug-induced fracture nonunion: an inhibition of angiogenesis?

BACKGROUND

Approximately 5% to 10% of fractures may result in delayed union or nonunion. The results of research done over the past three decades have shown that the use of nonsteroidal anti-inflammatory drugs (NSAIDs) has an inhibitory effect on fracture repair, but the exact mechanism of action remains to be elucidated. Cancer research has identified that NSAIDs impede cell proliferation by inhibiting angiogenesis. It is proposed that a similar mechanism occurs in the induction of NSAID-induced nonunions. This hypothesis was investigated in a randomized placebo-controlled trial of the NSAID rofecoxib with use of a murine femoral fracture model.

METHODS

Two hundred and forty mice were randomized to receive either the nonsteroidal anti-inflammatory drug rofecoxib (5 mg/kg orally) in a 0.5% methylcellulose solution (the NSAID group) or the 0.5% methylcellulose solution only (the control group). Two hundred and thirty-five of the 240 mice underwent surgery to induce an open transverse middiaphyseal femoral fracture, which was then treated with use of a custom-made external fixator. Five additional animals underwent sham surgery with no fracture induced. Outcomes measures included radiographic assessment, histologic analysis, biomechanical testing, and use of laser Doppler flowmetry to assess blood flow across the fracture gap.

RESULTS

Radiography revealed similar healing patterns in both groups; however, at the later stages (day 32), the NSAID group had poorer healing. Histological analysis demonstrated that the control animals healed quicker (at days 24 and 32) and had more callus and less fibrous tissue (at days 8 and 32) than the NSAID animals did. Biomechanical testing found that the control animals were stronger at day 32. Both groups exhibited a similar pattern of blood flow; however, the NSAID group exhibited a lower median flow from day 4 onward (significant at days 4, 16, and 24). Positive correlations were demonstrated between both histological and radiographic assessments of healing and increasing blood flow. NSAID-treated animals exhibited lower blood flow and poorer healing by all parameters. Regression analysis, however, demonstrated that the negative effect of NSAIDs on fracture repair is independent of its inhibitory action on blood flow.

CONCLUSIONS

Following the development of a novel method of analyzing functional vascularity across a fracture gap, we have demonstrated that the cyclooxygenase-2 (COX-2) inhibitor rofecoxib has a significant negative effect on blood flow across the fracture gap as well as an inhibiting effect on fracture repair.

CLINICAL RELEVANCE

COX-2 inhibitors are marketed as having low side-effect profiles. We propose that these drugs should be used with caution in all patients following osseous trauma and, in particular, after injuries that may already predispose a fracture to a delayed union due to osseous, vascular, or patient-related factors.

Does celecoxib have an adverse effect on bone remodeling and ingrowth in humans?

Although celecoxib may provide perioperative pain relief, the effect of the short-term use of celecoxib on bone ingrowth into porous-coated devices has not been previously studied in humans. Bone ingrowth into titanium and tantalum plugs was measured in nine patients who underwent staged bilateral total knee arthroplasty (TKA) and were taking celecoxib as part of a perioperative pain relief protocol. Patients were given tetracycline to measure the mineral apposition rate before and after celecoxib administration. Time zero plugs were implanted and retrieved during the first TKA, and 12 weeks later the contralateral implanted plugs were retrieved at the second TKA. The mineral apposition rate was similar for the titanium (0.97 microm per day) and the tantalum (1.15 microm per day) plugs at 12 weeks as was bone ingrowth (886 microm versus 632 microm, respectively). Celecoxib does not seem to inhibit bone ingrowth or bone formation.

Parecoxib impairs early metaphyseal bone healing in rats

INTRODUCTION

Cox2 inhibitors decrease prostaglandin production and therefore influence bone healing especially in unstable long bone models. It is unclear to what extent implant fixation in stable metaphyseal bone is impaired.

METHOD

Male rats numbering 30 and female rats numbering 40 received a stainless steel screw in the metaphyseal bone of the proximal tibia. Half of the rats were treated with 6.4 mg/kg BW parecoxib by continuous release from a subcutaneous mini pump during 7 or 14 days. After treatment, the pull out force, stiffness, and pull out energy of the screw were measured.

RESULTS

No effect of parecoxib on the pull out force was found for male rats. In female rats the pull out force was decreased by 16% (P = 0.03) after 7 days treatment with parecoxib. This effect had disappeared after 14 days.

CONCLUSION

Adverse effects of parecoxib on the early phase healing of metaphyseal bone in female rats are small and were not detectable after 14 days. No effect was seen in male rats, possibly due to a faster metabolic elimination of the drug.

Effect of COX-2 inhibitors and non-steroidal anti-inflammatory drugs on a mouse fracture model

A randomised, blinded, prospective animal study with 296 male C57BL/6N mice was performed to evaluate the biomechanical, biomolecular, biochemical, and histological impact of anti-inflammatory medications on fracture healing. A reproducible closed tibia fracture was created and stabilised with an intramedullary pin. Animals were randomised to placebo, ketorolac, ibuprofen, celecoxib, or rofecoxib treatment groups with biomechanical and biochemical testing at 4, 8, and 12 weeks. A second arm of the study was conducted in which animals were randomised to indomethacin or placebo treatment with biomechanical testing at 12 weeks. Histological and biomolecular studies were performed at 2 weeks on all groups in the first arm of the study. Biomechanical testing consisted of three-point bending evaluating maximum load, energy absorbed to maximum load, and stiffness. Safranin O-Fast Green stain was performed for histology. Biochemical quantifications of chondroitin and dermatan sulphate, hydroxyproline, total protein, and DNA content were performed. Osteocalcin and collagen types II and X were evaluated by in situ hybridisation. Some mechanical differences were seen between ketorolac and placebo at 4 weeks with respect to energy absorbed, but there were no differences in maximum load or stiffness seen between any treatment group and placebo at any time point. Indomethacin, celecoxib, rofecoxib, ibuprofen, and ketorolac did not significantly affect fracture healing in this young murine model.

Perioperative medication management for the patient with rheumatoid arthritis

The treatment of rheumatoid arthritis has improved dramatically in recent years with the advent of the latest generation of disease-modifying antirheumatic drugs. Despite these advances, in some patients inflammation is not diminished sufficiently to prevent irreversible musculoskeletal damage, thus requiring surgical intervention to reduce pain and improve function. In these cases, the orthopaedic surgeon frequently encounters patients on a drug regimen consisting of nonsteroidal anti-inflammatory drugs, glucocorticoids, methotrexate, and biologic agents (disease-modifying antirheumatic drugs). Consultation with a rheumatologist is recommended, but the surgeon also should be aware of these medications that could potentially affect surgical outcome. Prudent perioperative management of these drugs is required to optimize surgical outcome. A balance must be struck between minimizing potential surgical complications and maintaining disease control to facilitate postoperative rehabilitation of patients with rheumatoid arthritis.

Three-dimensional reconstruction of fracture callus morphogenesis

Rat and mouse femur and tibia fracture calluses were collected over various time increments of healing. Serial sections were produced at spatial segments across the fracture callus. Standard histological methods and in situ hybridization to col1a1 and col2a1 mRNAs were used to define areas of cartilage and bone formation as well as tissue areas undergoing remodeling. Computer-assisted reconstructions of histological sections were used to generate three-dimensional images of the spatial morphogenesis of the fracture calluses. Endochondral bone formation occurred in an asymmetrical manner in both the femur and tibia, with cartilage tissues seen primarily proximal or distal to the fractures in the respective calluses of these bones. Remodeling of the calcified cartilage proceeded from the edges of the callus inward toward the fracture producing an inner-supporting trabecular structure over which a thin outer cortical shell forms. These data suggest that the specific developmental mechanisms that control the asymmetrical pattern of endochondral bone formation in fracture healing recapitulated the original asymmetry of development of a given bone because femur and tibia grow predominantly from their respective distal and proximal physis. These data further show that remodeling of the calcified cartilage produces a trabecular bone structure unique to fracture healing that provides the rapid regain in weight-bearing capacity to the injured bone.

Sacral stress fractures

Sacral stress fractures are a relatively common occurrence and can be a debilitating source of low back pain. They generally occur in two distinctly different patient populations, and are of two different etiologies. Sacral insufficiency-type fractures are seen in elderly osteoporotic persons, and fatigue fractures are seen young active individuals. Although the clinical presentation of these fractures is similar, medical rehabilitation and interventional spine management strategies differ according to etiology. Although conservative management strategies have resulted in good outcomes, other treatment options have recently developed. This article provides an overview of the clinical presentation, pathology, and treatment options for sacral stress fractures and discusses some of the recent literature surrounding this interesting topic.

Pharmacologic agents in fracture healing

Bone fractures are a known risk of athletic participation and can result in significant lost playing time. A variety of medications have been investigated in animal studies regarding their effects on fracture healing. Parathyroid hormone and the bisphosphonates may have future uses in the prevention and treatment of athletic-related stress fractures and acute fractures. Nonsteroidal anti-inflammatory drugs have been implicated in effecting fracture healing in some animal models, but little clinical evidence supports these findings. Large randomized clinical trials are needed to further delineate the role of these and other drugs and their effects on fracture healing.

COX-2 has a Critical Role During Incorporation of Structural Bone Allografts

Nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit cyclooxygenase (COX) activity, reduced pain and are commonly used in patients with skeletal injury. In this article we will also present data to show that selective COX-2 inhibitor delays allograft healing and incorporation. In contrast, local delivery of prostaglandin E2 (PGE2) enhanced bone formation at cortical bone graft junction. A 4-mm mid-diaphyseal segmental femoral defect was created and then repaired by frozen bone allograft of the same size. A 22-gauge metal pin was placed in the intramedullary cavity to stabilize the bone graft. Healing was evaluated weekly by X ray and by a semiquantitative histomorphometric analysis at 5 weeks postsurgery. Celecoxib (25 mg/kg/day) and Ketorolac (4 mg/kg/day) were administered daily for 2 weeks or 5 weeks. PGE2 was infused locally at a dose of 800 nmol/kg per day via osmotic minipump for 4 weeks. Inhibition of cyclooxygenase by daily administration of the Celecoxib or Ketorolac for 5 weeks reduced new bone ingrowth by about 60% (P < 0.05). The percentage of bony bridging in both drug-treated groups was significantly decreased at 5 weeks. Temporal administration of Celecoxib for 2 weeks also significantly reduced bone formation by 45% and withdrawal of the Celecoxib only led to slight recovery of bone formation at the graft side. In contrast to the inhibitory effects of NSAIDS, PGE2 infusion at the cortical bone junction increased bone formation by about twofold. These results demonstrated that COX-2 is essential for bone allograft incorporation. Furthermore, our data support the notion that COX-2-dependent PGE2 produced at the early stage of bone healing is prerequisite for efficient skeletal repair.

Analgesic efficacy of parenteral paracetamol (propacetamol) and diclofenac in post-operative orthopaedic pain

BACKGROUND

Propacetamol is an injectable pro-drug of paracetamol (acetaminophen) with analgesic and antipyretic activities, especially used in the post-operative period. The aim of this study was to assess the analgesic efficacy and safety of intravenous paracetamol, administered as propacetamol, in comparison with placebo and intramuscular diclofenac in patients with post-operative pain.

METHODS

This was a randomized, double-blind, double-dummy study. One hundred and twenty patients with moderate to severe pain following total hip arthroplasty received either two administrations of propacetamol 2 g intravenously, 5 h apart (n = 40), one single administration of diclofenac 75 mg intramuscularly (n = 40) or placebo (n = 40). Efficacy measures were assessed before each drug administration, for the 5 h following each study treatment administration and for the total study duration of 10 h. Safety was assessed by reporting adverse events and changes in vital signs, electrocardiogram (ECG) and biochemical investigations before and 24 h after dosing.

RESULTS

Both active treatments were effective and statistically superior to placebo over the whole study period, as indicated by the total pain relief score. No significant differences were found between propacetamol and diclofenac for any measures of analgesic activity. Only minor and common adverse events were reported, with no overall differences between the groups.

CONCLUSION

Both active treatments were superior to placebo, and the overall efficacy of two intravenous infusions of propacetamol 2 g (equivalent to 1 g of paracetamol), 5 h apart, was not statistically different from that provided by a single intramuscular injection of diclofenac 75 mg over the first 5 h post-dose and over the total 10-h study period. The safety was good.

Pediatric acute pain management

Children are benefiting from the advances made in developmental neurobiology and analgesic pharmacology over the past few decades. Heightened public awareness and increased political pressure from external regulatory agencies are helping to maintain the momentum in improving pediatric pain management. As a result, methods of assessing and managing children's pain are being refined, and new modalities of pain relief are being explored. This review summarizes selected current topics in pediatric acute pain management, with the major emphasis on acute postoperative pain management.

Effects of perioperative antiinflammatory and immunomodulating therapy on surgical wound healing

Patients with various rheumatologic and inflammatory disease states commonly require drugs known to decrease the inflammatory or autoimmune response for adequate control of their condition. Such drugs include nonsteroidal antiinflammatory drugs (NSAIDs), cyclooxygenase (COX)-2 inhibitors, corticosteroids, disease-modifying antirheumatic drugs (DMARDs), and biologic response modifiers. These drugs affect inflammation and local immune responses, which are necessary for proper wound healing in the perioperative setting, thereby potentially resulting in undesirable postoperative complications. Such complications include wound dehiscence, infection, and impaired collagen synthesis. The end result is delayed healing of soft tissue and bone wounds. The current literature provides insight into the effect of some of these drugs on wound healing. For certain drugs, such as methotrexate, trials have been conducted in humans and direct us on what to do during the perioperative period. Whereas with other drugs, we must rely on either small-animal studies or extrapolation of data from human studies that did not specifically look at wound healing. Unfortunately, no clear consensus exists on the need and optimum time for withholding therapy before surgery. Likewise, clinicians are often uncertain of the appropriate time to resume therapy after the procedure. For those drugs with limited or no data in this setting, the use of pharmacokinetic properties and biologic effects of each drug should be considered individually. In some cases, discontinuation of therapy may be required up to 4 weeks before surgery because of the long half-lives of the drugs. In doing so, patients may experience an exacerbation or worsening of disease. Clinicians must carefully evaluate individual patient risk factors, disease severity, and the pharmacokinetics of available therapies when weighing the risks and benefits of discontinuing therapy in the perioperative setting.

The Anti-gastropathic and Anti-rheumatic Effect of Niga-ichigoside F1 and 23-Hydroxytormentic Acid Isolated from the Unripe Fruits of Rubus coreanus in a Rat Model

This study was undertaken to produce the clinical merits of two natural antinociceptive anti-inflammatory triterpenoids which synthetic anti-inflammatory drugs do not have. The triterpenoid glycoside niga-ichigoside F1 (NIF1) and its aglycone 23-hydroxytormentic acid (23-HTA), which were isolated from the unripe fruits of Rubus coreanus (Rosaceae), reduced rheumatoid arthritis (RA) factor and C-reactive protein (CRP) factor in Freund's complete adjuvant reagent-induced rats, suggesting that these two triterpenoids had an anti-rheumatic effect. It was also shown that treatment with NIF1 or 23-HTA reduced gastric lesion extent, acidity and total gastric acid output induced by EtOH plus sodium salicylate in a gastric secretion test. Moreover, 23-HTA had a greater effect than the glycoside, NIF1. To clarify the anti-gastropathic mechanism of these two compounds, their free radical scavenging activities in the gastric mucosa were examined in a rat EtOH-sodium salicylate-induced gastropathy model. The two compounds significantly increased superoxide dismutase and glutathione peroxidase activities, indicating that the healing effects of NIF1 and 23-HTA against gastropathy are associated with free radical scavenging enzyme activities. These results support the notion that the long-term administration of NIF1 or 23-HTA should overcome the adverse effects of synthetic anti-inflammatory drugs.

The role of cyclooxygenase-2 inhibition in foot and ankle arthrodesis

Cyclooxygenase-2 (COX-2) inhibitors are an important adjunct in controlling postoperative pain. Concerns exist regarding the use of NSAIDs for postoperative pain management because of the possible deleterious impact on bone healing in patients undergoing hindfoot arthrodesis. Orthopedic surgeons are concerned with: (1) a multimodal approach for postoperative pain control, and (2) bone healing following arthrodesis, fracture repair with rigid internal fixation, and cementless implants. The use of COX-2 inhibitors has been shown to be an important component of a pain control strategy but questions about their effects on bone healing have inhibited their use. This article discusses the laboratory and clinical data available on the use of COX-2 inhibitors on bone healing and their effects on foot and ankle arthrodesis procedures.

Selective COX-2 inhibitor reduces bone healing in bone defects

Anti-inflammatory agents have been reported to regulate bone healing. The aim of this study was to investigate the effect of a selective cyclooxygenase-2 inhibitor (meloxicam) on bone healing in calvarial defects in rats. Thirty-six adult male Wistar rats were included. After anesthesia, a linear incision was made through the skin of the scalp, a full-thickness flap was reflected and a 4 mm round defect was made with a trephine drill. The animals were randomly assigned to one of the following 4 treatment groups (9 animals each), including daily subcutaneous injections: A: saline solution for 15 days; B: saline solution for 45 days; C: 3 mg/kg of meloxicam for 15 days and D: 3 mg/kg of meloxicam for 45 days. The animals were sacrificed and the specimens, routinely processed. The bone filling was histometrically measured and statistical analysis, performed. Intergroup comparisons demonstrated that the meloxicam groups presented a significant reduction in bone healing when compared to their respective controls (group A, 44.5 ± 5.75%, against group C, 57.5 ± 7.25%, p < 0.05; group B, 40.25 ± 13.75%, against group D, 52.25 ± 17.25%). Within the limits of the present study, it can be concluded that selective cyclooxygenase-2 inhibitors may reduce bone healing in calvarial defects in rats after continuous administration.

Complications of operative fixation of proximal humeral fractures in patients with rheumatoid arthritis

Currently, there is no information in the literature on operative treatment of proximal humeral fractures in patients with rheumatoid arthritis. Eleven patients underwent osteosynthesis of the proximal humerus from December 1987 to December 2002. Nine patients were treated for acute fractures, and two were treated for nonunions. Four had loss of initial anatomic reduction, two were treated nonoperatively with resultant malunion, and two required revision fixation. Two patients with symptomatic pseudarthrosis were treated with internal fixation and bone grafting. Both had complications (1 requiring hemiarthroplasty after painful nonunion and 1 with chondrolysis). All patients with acute fractures achieved fracture union. One patient had an excellent result, four had satisfactory results, and six had an unsatisfactory result. Patients and treating physicians should be aware of the high rate of complications and unsatisfactory results in patients with rheumatoid arthritis who undergo operative treatment of proximal humeral fractures.

Cyclooxygenase-2 inhibition selectively attenuates bone morphogenetic protein-6 synthesis and bone formation during guided tissue regeneration in a rat model

OBJECTIVES

Bone formation during guided tissue regeneration is a tightly regulated process involving cells, extracellular matrix and growth factors. The aims of this study were (i) to examine the expression of cyclooxygenase-2 (COX-2) during bone regeneration and (ii) the effects of selective COX-2 inhibition on osseous regeneration and growth factor expression in the rodent femur model.

MATERIAL AND METHODS

A standardized transcortical defect of 5 x 1.5 mm was prepared in the femur of 12 male rats and a closed half-cylindrical titanium chamber was placed over the defect. The expression of COX-2 and of platelet-derived growth factor-B (PDGF-B), bone morphogenetic protein-6 (BMP-6) and insulin-like growth factor-I/II (IGF-I/II) was analyzed at Days 3, 7, 21 and 28 semiquantitatively by reverse transcriptase-polymerase chain reaction and immunohistochemistry. The effects of COX-2 inhibition by intraperitoneal injection of NS-398 (3 mg/kg/day) were analyzed in five additional animals sacrificed at Day 14.

RESULTS

Histomorphometry revealed that new bone formation occurred in the cortical defect area as well as in the supracortical region, i.e. region within the chamber by Day 7 and increased through Day 28. Immunohistochemical evidence of COX-2 and PDGF-B levels were observed early (i.e. Day 3) and decreased rapidly by Day 7. BMP-6 expression was maximal at Day 3 and slowly declined by Day 28. In contrast, IGF-I/II expression gradually increased during the 28-day period. Systemic administration NS-398 caused a statistically significant reduction (P<0.05) in new bone formation (25-30%) and was associated with a statistically significant reduction in BMP-6 protein and mRNA expression (50% and 65% at P<0.05 and P<0.01, respectively). PDGF-B mRNA or protein expression was not affected by NS-398 treatment.

CONCLUSION

COX-2 inhibition resulted in reduced BMP-6 expression and impaired osseous regeneration suggesting an important role for COX-2-induced signaling in BMP synthesis and new bone formation.

Celecoxib does not affect osteointegration of cementless total hip stems

Celecoxib's effect on prosthetic osteointegration in patients undergoing total hip arthroplasty was studied. In a prospective, placebo-controlled, double-blind study of 49 patients, 24 were randomized to celecoxib (200 mg/d) and 25 to placebo over 6 weeks. Bone markers, N-teleopeptide, and bone-specific alkaline phosphatase were obtained postoperatively, and at 6 and 12 weeks. No radiographic prosthetic subsidence occurred. There were no significant differences from baseline in periprosthetic bone mineral density between the celecoxib and placebo groups at 3 and 6 months. There were no significant differences in baseline BSAlkP values between the 2 groups. At 6 and 12 weeks, average BSAlkP values increased. Urinary NTx concentrations followed a skewed distribution. Normalized NTx concentrations were statistically significantly greater in the celecoxib group than the placebo group at 6 weeks but not at 12 weeks.

Application of histomorphometric methods to the study of bone repair

Standardized methods for the histomorphometric assessment of bone are essential features of most studies of metabolic bone diseases and their treatments. These methodologies were developed to assess coupled remodeling, focusing primarily on osteoblasts and osteoclasts, the anabolic and catabolic rates of these cells, and structural features of mature bone. Research studies on bone healing and the development of new therapeutic approaches for the enhancement of bone repair also require a comprehensive understanding of the basic cellular and tissue level mechanisms that underlie these processes. However, the histological methods developed for metabolic bone disease studies are not completely suitable for studies of bone repair because they are based on assumptions that there is little variation in tissue composition within a sample of bone and not generally designed to quantify other types of tissues, such as cartilage, that contribute to bone healing. These techniques also do not provide tissue-based structural measurements that are relatable to the specific types of biomechanical and radiographic structural assessments that are used to determine rates of bone healing. These deficiencies in current histological approaches therefore point to the need to establish standardized criteria for the histomorphometric assessments that are specifically adapted for the study of bone repair in models of fracture healing and bone regeneration. In this Perspective, we outline what we believe to be the specific structural, tissue. and cellular aspects that need to be addressed to establish these standardized criteria for the histomorphometric assessment of bone repair. We present the specific technical considerations that need to be addressed to appropriately sample repair tissues to obtain statistically meaningful results and suggest specific procedures and definitions of nomenclatures for the application of this technology to bone repair. Finally, we present how aspects of histomorphometric measurements of bone repair can be related to biomechanical and radiographic imaging properties that functionally define rates of bone healing, and thus, how these tools can be used to provide corroborating data.

Nonsteroidal antiinflammatory drugs and nonunion of humeral shaft fractures

OBJECTIVE

To analyze the relationship between nonunion of humeral shaft fractures and nonsteroidal antiinflammatory drug (NSAID) exposure in older adults.

METHODS

A cohort of 9,995 patients with humeral shaft fractures was identified using diagnosis and procedure codes from a Medicare database of >500,000 patients. Prescription NSAID as well as prescription opioid use was assessed from pharmacy claims data for 3 30-day periods immediately after the initial fracture. Nonunion was defined by the presence of procedure codes for repair of nonunion 90-365 days after the index fracture. We examined the association between NSAIDs and nonunion using multivariate Cox proportional hazards models.

RESULTS

Of the 9,995 humeral shaft fractures, 105 patients developed nonunions (1.1%), and 1,032 (10.3%) were exposed to NSAIDs in the 90 days after fracture. NSAID exposure within the first 90 days was significantly associated with nonunion (relative risk [RR] 3.7, 95% confidence interval [95% CI] 2.4-5.6). When indicators for exposure to NSAIDs during each of the 3 30-day windows were placed into the same multivariate model, only the period 61-90 days post-fracture was significantly associated with nonunion (RR 3.9, 95% CI 2.0-6.2). We observed a similar association between opioids and nonunion, with exposure to opioids between 61 and 90 days associated with nonunion (RR 2.7, 95% CI 1.5-5.2), but exposure to opioids during neither of the 2 earlier 30-day periods significantly associated with nonunion.

CONCLUSION

We found that exposure to nonselective NSAIDs or opioids in the period 61-90 days after a humeral shaft fracture was associated with nonunion. Although these associations may be causal, they are more likely to reflect the use of analgesics by patients with painful nonhealing fractures.

Pain management for the hospitalized pediatric patient

Pediatric hospitalists should make pain assessment and treatment a high priority and a central part of their daily practice. Efforts at improving pain treatment in pediatric hospitals should be multidisciplinary and should involve combined use of pharmacologic and nonpharmacologic approaches. Although available information can permit effective treatment of pain for most children in hospitals, there is a need for more research on pediatric analgesic pharmacology, various nonpharmacologic treatments, and different models of delivery of care.

Cyclooxygenase-2 inhibitor delays fracture healing in rats

BACKGROUND

Cyclooxigenase-2 (COX-2) inhibitors have been reported to delay fracture healing. To investigate the major inhibitory period of COX-2 inhibitors in fracture healing, we administrated etodolac, a COX-2-specific inhibitor, to a rat fracture model by altering the period of administration from early to late.

METHOD

After closed fractures had been created at the middle of the femoral shafts in 12-week-old Wister rats, a standardized dose of etodolac was administrated in three ways: group I received it for 3 weeks, group II for just the first week after operation, and group III for just the third (final) week. Group IV was the vehicle control group. Bone maturation was estimated by radiographic scoring system, and mechanically by a three-point bending test.

RESULTS AND INTERPRETATION

In both the radiographic and mechanical studies, groups I and II showed lower scores than group IV, indicating that even a short period of administration of a COX-2-specific inhibitor in the early phase of fracture healing creates a risk of delayed healing. blacksquare, square, filled.