The Effect of Cyclooxygenase-2 Inhibitors on Bone Healing:

The Role of COX-2 and PGE2 in the Regulation of Immunomodulation and Other Functions of Mesenchymal Stromal Cells

The ability of MSCs to modulate the inflammatory environment is well recognized, but understanding the molecular mechanisms responsible for these properties is still far from complete. Prostaglandin E2 (PGE2), a product of the cyclooxygenase 2 (COX-2) pathway, is indicated as one of the key mediators in the immunomodulatory effect of MSCs. Due to the pleiotropic effect of this molecule, determining its role in particular intercellular interactions and aspects of cell functioning is very difficult. In this article, the authors attempt to summarize the previous observations regarding the role of PGE2 and COX-2 in the immunomodulatory properties and other vital functions of MSCs. So far, the most consistent results relate to the inhibitory effect of MSC-derived PGE2 on the early maturation of dendritic cells, suppressive effect on the proliferation of activated lymphocytes, and stimulatory effect on the differentiation of macrophages into M2 phenotype. Additionally, COX-2/PGE2 plays an important role in maintaining the basic life functions of MSCs, such as the ability to proliferate, migrate and differentiate, and it also positively affects the formation of niches that are conducive to both hematopoiesis and carcinogenesis.

Alcoholism as a predictor for pseudarthrosis in primary spine fusion: An analysis of risk factors and 30-day outcomes for 52,402 patients from 2005 to 2013

Introduction

This study assessed the incidence and risk factors for pseudarthrosis among primary spine fusion patients.

Methods

Retrospective review of ACS-NSQIP (2005-2013). Differences in comorbidities between spine fusion patients with and without pseudarthrosis (Pseud, N-Pseud) were assessed using chi-squared tests and Independent Samples t-tests. Binary logistic regression assessed patient-related and procedure-related predictors for pseudarthrosis.

Results

52,402 patients (57yrs, 53%F, 0.4% w/pseudarthrosis). Alcohol consumption (OR:2.6[1.2-5.7]) and prior history of surgical revision (OR:1.6[1.4-1.8]) were risk factors for pseudarthrosis operation. Pseud patients at higher risk for deep incisional SSI (at 30-days:OR:6.6[2.0-21.8]). Pseud patients had more perioperative complications (avg:0.24 ± 0.43v0.18 ± 0.39,p=0.026).

Conclusions

Alcoholism and surgical revision are major risk factors for pseudarthrosis in patients undergoing spine fusion.

Nonsteroidal Anti-Inflammatory Drugs and Bone-Healing: A Systematic Review of Research Quality

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are often avoided by orthopaedic surgeons because of their possible influence on bone-healing. This belief stems from multiple studies, in particular animal studies, that show delayed bone-healing or nonunions associated with NSAID exposure. The purpose of this review was to critically analyze the quality of published literature that evaluates the impact of NSAIDs on clinical bone-healing.

METHODS

A MEDLINE and Embase search was conducted to identify all articles relating to bone and fracture-healing and the utilization of NSAIDs. All human studies, including review articles, were identified for further analysis. Non-English-language manuscripts and in vitro and animal studies were excluded. A total of twelve clinical articles and twenty-four literature reviews were selected for analysis. The quality of the clinical studies was assessed with a modified Coleman Methodology Score with emphasis on the NSAID utilization. Review articles were analyzed with regard to variability in the cited literature and final conclusions.

RESULTS

The mean modified Coleman Methodology Score (and standard deviation) was significantly lower (p = 0.032) in clinical studies that demonstrated a negative effect of NSAIDs on bone-healing (40.0 ± 14.3 points) compared with those that concluded that NSAIDs were safe (58.8 ± 10.3 points). Review articles also demonstrated substantial variability in the number of cited clinical studies and overall conclusions. There were only two meta-analyses and twenty-two narrative reviews. The mean number (and standard deviation) of clinical studies cited was significantly greater (p = 0.008) for reviews that concluded that NSAIDs were safe (8.0 ± 4.8) compared with those that recommended avoiding them (2.1 ± 2.1). Unanimously, all reviews admitted to the need for prospective randomized controlled trials to help clarify the effects of NSAIDs on bone-healing.

CONCLUSIONS

This systematic literature review highlights the great variability in the interpretation of the literature addressing the impact of NSAIDs on bone-healing. Unfortunately, there is no consensus regarding the safety of NSAIDs following orthopaedic procedures, and future studies should aim for appropriate methodological designs to help to clarify existing discrepancies to improve the quality of care for orthopaedic patients.

CLINICAL RELEVANCE

This systematic review highlights the limitations in the current understanding of the effects of NSAIDs on bone healing. Thus, withholding these medications does not have any proven scientific benefit to patients and may even cause harm by increasing narcotic requirements in cases in which they could be beneficial for pain management. This review should encourage further basic-science and clinical studies to clarify the risks and benefits of anti-inflammatory medications in the postoperative period, with the aim of improving patient outcomes.

Osteoinductive effects of preoperative dexamethasone in human dental pulp stem cells primary culture

AIM

The use of dexamethasone (DEX) in mesenchymal cell culture induces osteoblastic differentiation and, consequently, formation of mineralized tissues. Tissue engineering proposes the development of therapeutic strategies aimed at structural and functional regeneration of biological tissues. In this sense, cell characterization in vitro is critical to ensure the development of such techniques. Our objective was to evaluate the osteoinductive effect of DEX administered as a preoperative medication in primary cell culture of human dental pulp stem cell.

METHODOLOGY

Cells from the third molar pulp were divided into two experimental groups, each with two preoperative medication protocols used in dental practice and differentiated by the intake of DEX in one of them. The assessment of proliferation, differentiation and viability through trypan blue, methylthiazol tetrazolium, and von Kossa and alizarin red assays, respectively, were held within fixed intervals: 7, 14, 21 and 28 days.

CONCLUSION

This study has shown that DEX may influence in vitro human dental pulp stem cell behavior.

The effect of NSAIDs on spinal fusion: a cross-disciplinary review of biochemical, animal, and human studies

PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) play an important role in postoperative pain management. However, their use in the setting of spine fusion surgery setting has long been a topic of controversy. In this review we examined relevant research, including in vivo, animal, and clinical human studies, with the aim of understanding the effect of NSAIDs on spinal fusion.

STUDY DESIGN/SETTING

Systematic review of study designs of all types from randomized controlled trials and meta-analyses to single-institution retrospective reviews.

METHODS

A search of PubMed and Embase was conducted using the keywords: "spine," "spinal fracture," NSAIDs, anti-inflammatory non-steroidal agents, bone, bone healing, fracture, fracture healing, yielding a total of 110 studies. Other 28 studies were identified by cross-referencing, resulting in total 138 studies.

RESULTS

There is no level I evidence from human studies regarding the use of NSAIDs on spinal fusion rates. The overall tone of the spine literature in the early 2000s was that NSAIDs increased the rate of non-union; however, nearly all human studies published after 2005 suggest that short-term (<2 weeks) postoperative use have no such effect. The dose dependency that is seen with a 2-week postoperative course is not present when NSAIDs are only used for 48 h after surgery.

CONCLUSIONS

NSAID appear to have dose-dependent and duration-dependent effects on fusion rates. The short-term use of low-dose NSAIDs around the time of spinal fusion surgery is reasonable. Spine surgeons can consider the incorporation of NSAIDs into pain control regimens for spinal fusion patients with the goal of improving pain control and reducing the costs and complications associated with opioids.

Impact of surgical site infection and surgical debridement on lumbar arthrodesis: A single-institution analysis of incidence and risk factors

This study identifies the rate of pseudarthrosis following surgical debridement for deep lumbar spine surgical site infection and identify associated risk factors. Patients who underwent index lumbar fusion surgery from 2013 to 2014 were included if they met the following criteria: 1) age >18years, 2) had debridement of deep lumbar SSI, and had 3) lumbar spine AP, lateral and flexion/extension X-rays and computed tomography (CT) at 12months or greater postoperatively. Criteria for fusion included 1) solid posterolateral, facet, or disk space bridging bone, 2) no translational or angular motion on flexion/extension X-rays, and 3) intact posterior hardware without evidence of screw lucency or breakage. Twenty-five patients (age 63.2±12.6years, 10 male) involving 58 spinal levels met inclusion criteria. They underwent fusion at a mean of 2.32 [range 1-4] spinal levels. Sixteen (64.0%) patients received interbody grafts at a total of 34 (58.6%) spinal levels. All underwent surgical debridement with removal of all non-incorporated posterior bone graft and devascularized tissue. At one-year postoperatively, (56%) patients and 30 (52%) spinal levels demonstrated radiographic evidence of successful fusion. Interbody cage during initial fusion was significantly associated with successful arthrodesis at follow-up (p=0.017). There is a high rate of pseudoarthrosis in 44% of patients (48% of levels) undergoing lumbar fusion surgery complicated by SSI requiring debridement. Use of interbody cage during initial fusion was significantly associated with higher rate of arthrodesis.

Influence of non-steroidal anti-inflammatory drugs (NSAIDs) on osseointegration of dental implants in rabbit calvaria

AIM

Until recently, adverse effects of non-steroidal anti-inflammatory drugs (NSAIDs) on osseointegration of dental implants were unknown. Hence, this study investigated the short- and long-term effects of a 7-day regimen of parecoxib and diclofenac sodium on osseointegration of dental implants in calvarial bone.

MATERIAL AND METHODS

Eighteen New Zealand White rabbits were randomly allocated into three groups (each n = 6): Control group with no postoperative pain killers (Group A), diclofenac group (Group B) and parecoxib group (Group C). In each animal, one dental implant was placed into the calvarial bone (total n = 18). Three rabbits from each group were sacrificed in Week 4. The other three rabbits from each group were sacrificed in Week 12 postoperatively. The implant together with the calvarial bone and dura mater was harvested and subjected to micro-computed tomography (micro-CT) and histomorphometric analysis.

RESULTS

Quantitative analysis of micro-CT data and histomorphometric data neither revealed any statistically significant (P ≤ 0.05) differences between the three different groups related to osseointegration nor between different time points of observation.

CONCLUSION

In rabbits, a 7-day regimen of appropriate doses of diclofenac sodium and parecoxib did not adversely affect osseointegration of dental implants and bone healing in calvaria, neither short nor long term (12 weeks).

Valdecoxib for the management of chronic and acute pain

Cyclooxygenase-2 specific inhibitors have anti-inflammatory and analgesic properties, and are effective in managing a wide range of chronic and acute painful conditions such as adult rheumatoid arthritis, osteoarthritis, migraine, primary dysmenorrhea and postoperative pain. Valdecoxib, an orally administered cyclooxygenase-2 specific inhibitor, provides effective pain relief for both chronic and acute conditions, and reduces postoperative opioid use, with a concomitant reduction in opioid-related adverse events. Valdecoxib also has superior gastrointestinal safety compared with nonspecific nonsteroidal anti-inflammatory drugs, and at therapeutic doses, it is generally safe and well tolerated in terms of renal and cardiovascular events. This drug profile reviews the efficacy, safety and tolerability of valdecoxib for the management of chronic and acute pain.

Strategies Aimed at Preventing Chronic Post-surgical Pain: Comprehensive Perioperative Pain Management after Total Joint Replacement Surgery

PURPOSE

Chronic post-surgical pain (CPSP) is a frequent outcome of musculoskeletal surgery. Physiotherapists often treat patients with pain before and after musculoskeletal surgery. The purposes of this paper are (1) to raise awareness of the nature, mechanisms, and significance of CPSP; and (2) to highlight the necessity for an inter-professional team to understand and address its complexity. Using total joint replacement surgeries as a model, we provide a review of pain mechanisms and pain management strategies.

SUMMARY OF KEY POINTS

By understanding the mechanisms by which pain alters the body's normal physiological responses to surgery, clinicians selectively target pain in post-surgical patients through the use of multi-modal management strategies. Clinicians should not assume that patients receiving multiple medications have a problem with pain. Rather, the modern-day approach is to manage pain using preventive strategies, with the aims of reducing the intensity of acute postoperative pain and minimizing the development of CPSP.

CONCLUSIONS

The roles of biological, surgical, psychosocial, and patient-related risk factors in the transition to pain chronicity require further investigation if we are to better understand their relationships with pain. Measuring pain intensity and analgesic use is not sufficient. Proper evaluation and management of risk factors for CPSP require inter-professional teams to characterize a patient's experience of postoperative pain and to examine pain arising during functional activities.

NSAIDS inhibit in vitro MSC chondrogenesis but not osteogenesis: implications for mechanism of bone formation inhibition in man

The non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for analgesia but may inhibit bone formation. We investigated whether the reported NSAID effect on bone is related to inhibition of bone marrow mesenchymal stem cell (MSC) proliferation and osteogenic and chondrogenic differentiation and evaluated both cyclooxygenase (COX)-1 and COX-2 specific drugs. The effects of seven COX-1 and COX-2 inhibitors on MSC proliferation and osteogenic and chondrogenic differentiation were tested using Vybrant, sodium 3'-[1-(phenylaminocarbonyl)- 3,4-tetrazolium]-bis (4-methoxy-6-nitro) benzene sulfonic acid hydrate (XTT), functional and quantitative assays of MSC differentiation. The MSC expression of COX-1 and COX-2 and prostaglandin E2 (PGE-2) levels were evaluated serially during lineage differentiation by quantitative PCR and ELISA. None of the NSAIDs at broad range of concentration (range 10(-3) to 100 μg/ml) significantly affected MSC proliferation. Surprisingly, MSC osteogenic differentiation inhibition was not evident. However, NSAIDs affected chondrogenic potential with a reduction in sulphated glycosaminoglycans (sGAG) content by 45% and 55% with diclofenac and ketorolac, respectively (P < 0.05 compared to controls). Parecoxib and meloxicam, more COX-2 specific reagents inhibited sGAG to a lesser degree, 22% and 27% respectively (P < 0.05 compared to controls). Cartilage pellet immunohistochemistry confirmed the above results. Pellet chondrogenesis was associated with increased COX-1 expression levels but not COX-2, and COX-1 specific drugs suppressed MSC PGE-2 more than COX-2 specific inhibitors. These findings suggest that NSAIDs may inhibit bone formation via blockage of MSC chondrogenic differentiation which is an important intermediate phase in normal endochondral bone formation.

High-dose ketorolac affects adult spinal fusion: a meta-analysis of the effect of perioperative nonsteroidal anti-inflammatory drugs on spinal fusion

STUDY DESIGN

Meta-analysis of literature.

OBJECTIVE

To evaluate the effect of perioperative nonsteroidal anti-inflammatory drugs (NSAIDs) on the success rate of adult spinal fusion.

SUMMARY OF BACKGROUND DATA

NSAIDs are commonly used to treat postsurgical orthopedic pain. Studies on animal models have shown a significant inhibiting effect of NSAIDs on osteogenesis process, on which spinal fusion also depends. Recently, great interest has been shown in the effect of NSAIDs on the success rate of adult spinal fusion. Clinical trials have tested the effect of perioperative NSAIDs in spinal fusion procedures. A cumulative result of these studies would give more credit to the final conclusions.

METHODS

A systematic search of electronic databases and references from eligible articles was conducted. Comparative studies reporting on the results of primary spinal fusion including treatment group of NSAIDs perioperatively were regarded eligible. A pooled estimate of effect size was produced using both random and fixed effect model.

RESULTS

Five retrospective comparative studies (n = 1403 participants) were included in the present study. The mean age of these patients was more than 40 years and none of them had NSAIDs for longer than 14 days following spinal fusion surgery. High-dose ketorolac showed a statistically significant adverse effect on spinal fusion (P = 0.001, RR = 2.87, 95% CI = 1.53 = - 5.38) with no statistical heterogeneity (I = 3%, P = 0.38), whereas normal-dose NSAIDs (ketorolac, diclofenac sodium, celecoxib, or rofecoxib) did not appear to produce inferior results than the no-NSAIDs group (P = 0.30, RR = 1.39, 95% CI = 0.74 - 2.61) with no statistical heterogeneity (I² = 0%, P = 0.50).

CONCLUSION

Although randomized controlled trials would be optimal for meta-analyses, the data of this review revealed that short-time (<14 days) exposure to normal-dose NSAIDs (ketorolac, diclofenac sodium, celecoxib, or rofecoxib) were safe after spinal fusion, whereas short-time (<14 days) exposure to high-dose ketorolac increased the risk of nonunion, which meant that the effect of perioperative NSAIDs on spinal fusion might be dose-dependent. Further studies would be needed to find out whether long-time exposure to normal-dose NSAIDs could also increase the risk of nonunion and which type of NSAIDs would like to have a worse effect on spinal fusion.

Parecoxib has non-significant long-term effects on bone healing in rats when administered for a short period after fracture

INTRODUCTION

Selective and non-selective cyclo-oxygenase (COX) inhibitors impair bone healing by inhibiting prostaglandin synthesis. The purpose of this study was to evaluate the long-term effect of parecoxib, a selective COX-2 inhibitor, on bone healing in rats, when it is applied in a pattern similar to clinical treatment patterns, that is, in a high dose and for a short period after bone fracture.

METHOD

Closed non-displaced mid-diaphyseal fractures in the middle of the left femoral shaft were generated in each animal. In the study group, parecoxib sodium (1.06 mg/kg) was administered intra-peritoneally every day for 7 days. In the control group, normal saline was administered intra-peritoneally every day for 7 days. In both groups fracture healing (bone union and callus formation) was evaluated with X-rays 28 and 42 days after surgery.

RESULTS

Bone healing was lower in the study group (60 vs. 80% in the control group 28 days after fracture and 80 vs. 90% 42 days after fracture) but this difference was not statistically significant (P > 0.05).

CONCLUSION

Parecoxib does not have a significant long-term effect on bone healing in rats, when it is administered in a high dose and for a short period after bone fracture.

The use of NSAIDs in pediatric scoliosis surgery - a survey of physicians' prescribing practice

BACKGROUND

Pediatric scoliosis surgery is associated with considerable postoperative pain requiring opioids for analgesia. Nonsteroidal antiinflammatory drugs (NSAIDs) can be used as adjuvants for analgesia; however, the potential of these agents to affect bone healing raises concerns. No large-scale prospective studies have been performed to evaluate the benefit-to-risk ratio of NSAID use after pediatric scoliosis surgery. Given the lack of evidence in the literature, a survey of practice patterns of anesthesiologists from around the world was conducted with respect to the use of NSAIDs after pediatric spinal fusion surgery for scoliosis.

METHODS

One hundred and fourteen anesthesiologists from international academic pediatric hospitals were asked to complete an online survey. After 1 month, nonresponders were sent a second e-mail asking for their participation. All questions were developed specifically for this study.

RESULTS

Out of 80 anesthesiologists who responded 61 were included in the final analysis. Fifty-nine percent routinely use NSAIDs, the most common agents being intravenous ketorolac and oral ibuprofen. The majority of respondents begin to administer NSAIDs within the first three postoperative days for a duration of four or more days. The primary reason for not routinely prescribing NSAIDs was the risk of bone nonunion.

CONCLUSIONS

This survey demonstrates that the practice patterns of pediatric anesthesiologists from around the world with respect to the administration of NSAIDs for the management of postoperative pain after pediatric spinal fusion reflects the conflicting evidence in the literature and the lack of high-quality studies in humans.

Pathophysiology of cyclooxygenase inhibition in animal models

Cyclooxygenase (COX) catalyzes the conversion of arachidonic acid into prostaglandins (PGs), which play a significant role in health and disease in the gastrointestinal tract (GI) and in the renal, skeletal, and ocular systems. COX-1 is constitutively expressed and found in most normal tissues, whereas COX-2 can be expressed at low levels in normal tissues and is highly induced by pro-inflammatory mediators. Inhibitors of COX activity include: (1) conventional nonselective, nonsteroidal anti-inflammatory drugs (ns-NSAIDs) and (2) COX-2 selective nonsteroidal anti-inflammatory drugs (COX-2 s-NSAIDs). Inhibition of COX-1 often elicits GI toxicity in animals and humans. Therefore, COX-2 s-NSAIDs were developed to provide a selective COX-2 agent, while minimizing the attendant COX-1-mediated GI toxicities. Rats and dogs overpredict COX inhibition for renal effects such as renal handling of electrolytes in humans. COX inhibitors are shown to have both beneficial and detrimental effects, such as on healing of ligament or tendon tears, on the skeletal system in animal models. Certain ophthalmic conditions such as glaucoma and keratitis are associated with increased COX-2 expression, suggesting a potential role in their pathophysiology.

Influence of nonsteroidal anti-inflammatory drugs on osseointegration

This paper reviews contemporary literature concerning the possible influence of nonsteroidal anti-inflammatory drugs (NSAIDs) on osseointegration. In vitro studies concerning the effect of NSAIDs on growth factors and bone-generating cells are the primary source of data pertaining to this issue because relatively few in vivo studies have been conducted. It is concluded that prescribing NSAIDs during the early postoperative period is likely not without negative effect, although any negative influence appears to be temporary and does not affect the final outcome of osseointegration.

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.

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 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.

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.

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.

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.

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.

Role of cyclooxygenase-2 inhibitors in postoperative pain management

Cyclooxygenase (COX)-2 inhibitors are as efficacious as nonselective nonsteroidal anti-inflammatory drugs for the treatment of postoperative pain but have the advantages of a better gastrointestinal side-effect profile as well as a lack of antiplatelet effects. There have been recent concerns regarding the cardiovascular side effects of COX-2 inhibitors. Nonetheless, they remain a valuable option for postoperative pain management. The pharmacology of these agents and available studies are reviewed.

High dose nonsteroidal anti-inflammatory drugs compromise spinal fusion

PURPOSE

Although nonsteroidal anti-inflammatory drugs (NSAIDs) provide benefit to patients following spinal fusion surgery, their routine administration has remained controversial due to concerns about possible deleterious effects on bone healing. The goal of this retrospective study was to assess the incidence of non-union following the perioperative administration of ketorolac, celecoxib, or rofecoxib.

METHODS

We retrospectively analyzed the data of 434 patients receiving perioperative ketorolac (20-240 mg.day(-1)), celecoxib (200-600 mg.day(-1)), rofecoxib (50 mg.day(-1)), or no NSAIDs in the five days following spinal fusion surgery.

RESULTS

There were no significant differences in the incidence of non-union among the groups that received no NSAIDs (11/130; 8.5%), celecoxib 5/60; 8.3%), or rofecoxib (9/124; 7.3%). In contrast, 23/120 of patients (19.2%) that received ketorolac had a higher incidence (P < 0.001) of non-union compared to non-NSAID users. However, only 3/50 patients (6%) receiving low-dose ketorolac (< or = 110 mg.day(-1)) resulted in non-union which was not significantly different from non-NSAID users. Patients administered higher doses of ketorolac (120-240 mg.day(-1)) resulted in a higher incidence (P < 0.0001) of non-union (20/70; 29%) compared to non-NSAID users. For those patients developing non-union, there was a higher incidence comparing smokers vs non-smokers (P < 0.0001) and one level fusion vs two level fusions (P < 0.001).

CONCLUSIONS

This study revealed that the short-term perioperative administration of celecoxib, rofecoxib, or low-dose ketorolac (< or = 110 mg.day(-1)) had no significant deleterious effect on non-union. In contrast, higher doses of ketorolac (120-240 mg.day(-1)), history of smoking, and two level vertebral fusions resulted in a significant increase in the incidence of non-union following spinal fusion surgery.

The effect of cyclooxygenase-2 inhibition on analgesia and spinal fusion

BACKGROUND

Cyclooxygenase (COX)-2-specific inhibitors demonstrate analgesic efficacy comparable with that of conventional nonsteroidal anti-inflammatory drugs but are associated with reduced gastrointestinal side effects and an absence of antiplatelet activity. Thus, they can be administered to patients undergoing spinal fusion surgery without an added risk of bleeding. However, concerns regarding a possible deleterious effect on bone-healing have limited their routine use. Celecoxib, a COX-2 inhibitor, recently was approved for the treatment of acute pain. The goals of the present study were to examine the analgesic efficacy of celecoxib and to determine the incidence of nonunion at one year following spinal fusion surgery.

METHODS

Eighty patients who were scheduled to undergo spinal fusion received either celecoxib or placebo one hour before the induction of anesthesia and every twelve hours after surgery for the first five postoperative days. Pain scores and morphine use were recorded one hour after arrival in the post-anesthesia care unit and at four, eight, twelve, sixteen, twenty, and twenty-four hours later. Intraoperative blood loss was recorded. The status of the fusion was determined radiographically at the time of the one-year follow-up.

RESULTS

There were no differences in demographic data or blood loss between the two groups. Pain scores were lower in the celecoxib group at one, four, eight, sixteen, and twenty hours postoperatively. There were no differences between the two groups with regard to the pain scores at twelve and twenty-four hours postoperatively. Morphine use was lower in the celecoxib group at all postoperative time-intervals. There was no difference between the celecoxib group and the placebo group with regard to the incidence of nonunion at the time of the one-year follow-up (7.5% [three of forty] compared with 10% [four of forty]).

CONCLUSIONS

The perioperative administration of celecoxib resulted in a significant reduction in postoperative pain and opioid use following spinal fusion surgery. In addition, the short-term administration of this COX-2-specific non-steroidal anti-inflammatory drug had no apparent effect on the rate of nonunion at the time of the one-year follow-up.

Strategies for postoperative pain management

Despite advances in our understanding of the neurobiology of nociception, postoperative pain continues to be undertreated. There are many modalities that may provide effective postoperative analgesia, including systemic (e.g. opioids, non-steroidal anti-inflammatory agents) and regional analgesic options. The particular modality or modalities utilized for a particular patient will depend on the risk-benefit profile and patient preferences. Ideally, analgesic options should be incorporated into a multimodal approach to facilitate patient recovery after surgery.