The effect of indomethacin upon experimental fractures in the rat

The effect of NSAIDs on postfracture bone healing: a meta-analysis of randomized controlled trials

To determine whether nonsteroidal anti-inflammatory drugs (NSAIDs) have an adverse effect on bone healing by evaluating all available human randomized controlled trials (RCTs) on this subject.

Data Sources

A comprehensive search of electronic databases (PubMed, MEDLINE, and Cross-References) until October 2018 comparing the occurrence of nonunion in patients who received NSAIDs to the control group through RCTs.

Study Selection

Inclusion criteria were English-only studies, and the type of studies was restricted to RCTs.

Data Extraction

Two authors independently extracted data from the selected studies, and the data collected were compared to verify agreement.

Data Synthesis

Nonunion was the main outcome evaluated in each study. Regression analysis was used to estimate the relative risk comparing the duration and the type of NSAIDs by calculating the odds ratio (OR) for dichotomous variables. Studies were weighed by the inverse of the variance of the outcome, and a fixed-effects model was used for all analyses.

Conclusions

Six RCTs (609 patients) were included. The risk of nonunion was higher in the patients who were given NSAIDs after the fracture with an OR of 3.47. However, once the studies were categorized into the duration of treatment with NSAIDs, those who received NSAIDs for a short period (<2 weeks) did not show any significant risk of nonunion compared to those who received NSAIDs for a long period (>4 weeks). Indomethacin was associated with a significant higher nonunion rate and OR ranging from 1.66 to 9.03 compared with other NSAIDs that did not show a significant nonunion risk.

Characteristics of complete tibial fractures in California racehorses

BACKGROUND

Tibial fractures cause ~3% of racehorse deaths. Pre-existing stress fractures have been associated with multiple racing and training fractures, but not complete tibial fractures.

OBJECTIVES

To describe racehorse tibial fractures and compare signalment and exercise histories of affected and control racehorses.

STUDY DESIGN

Retrospective analysis of necropsy reports.

METHODS

Racehorses that had a complete tibial fracture (1990-2018) were retrospectively reviewed. Signalment and exercise histories of affected horses were compared to 1) racehorses that died because of non-tibial musculoskeletal injuries or 2) non-musculoskeletal cause and 3) age, sex, event-matched control racehorses. Tibial fracture prevalence was described relative to California racehorses that had at least one official work or race. Age, sex and limb distributions were compared between affected and control horses (Chi-square, Fisher's Exact test). Exercise history data were reduced to counts and rates of official high speed works, races and layups (periods without an official high speed work or race >60 days). Variables were compared among groups using matched logistic regression (P ≤ .05).

RESULTS

Tibial fractures in 115 horses (97% unilateral; 50% left, 47% right) occurred most commonly during training (68%) and in 2- to 3-year-old horses (73%). Fractures were predominantly comminuted (93%), diaphyseal (44%) and oblique (40%). Of 61 cases examined for callus, 64% had periosteal callus associated with fracture, most commonly in proximal (65%) and distal diaphyseal (27%) locations. Of 28 racehorses with known exercise history, 57% never raced and 36% had a layup. Affected horses had fewer official-timed works and events (official high speed works and races), number of active days and accumulated less distance in events and works (P < .05) than control horses.

MAIN LIMITATIONS

Retrospective review of necropsy reports by multiple pathologists over 28 years.

CONCLUSIONS

Tibial fractures were associated with pre-existing stress fracture early in career. Most fractures were associated with proximolateral stress fractures.

Effect of NSAID Use on Bone Healing in Pediatric Fractures: A Preliminary, Prospective, Randomized, Blinded Study

BACKGROUND

This study aimed to investigate if nonsteroidal anti-inflammatory drugs (NSAIDs) used in the acute phase of bone healing in children with fractures result in delayed union or nonunion as compared with patients who do not take NSAIDs for pain control during this same time period.

METHODS

In this prospective, randomized, parallel, single-blinded study, skeletally immature patients with long bone fractures were randomized to 1 of 2 groups for their postfracture pain management. The NSAID group was prescribed weight-based ibuprofen, whereas the control group was not allowed any NSAID medication and instead prescribed weight-based acetaminophen. Both groups were allowed to use oxycodone for breakthrough pain. The primary outcome was fracture healing assessed at 2, 6, and 10 weeks.

RESULTS

One-hundred-two patients were enrolled between February 6, 2014 and September 23, 2016. Ninety-five patients (with 97 fractures) completed a 6-month follow-up (46 patients with 47 fractures in the control group and 49 patients 50 fractures in the NSAID group). None achieved healing at 1 to 2 weeks. By 6 weeks, 37 of 45 patients (82%) of control group and 46 out of 50 patients (92%) of ibuprofen group had healed fractures (P=0.22). At 10 to 12 week follow-up, 46 (98%) of the control group fractures were healed and 50 (100%) of the ibuprofen group fractures were healed. All were healed by 6 months. Healing was documented at a mean of 40 days in the control group and 31 days in the ibuprofen group (P=0.76). The mean number of days breakthrough oxycodone was used was 2.4 days in the control group and 1.9 days in the NSAID group (P=0.48).

CONCLUSION

Ibuprofen is an effective medication for fracture pain in children and its use does not impair clinical or radiographic long bone fracture healing in skeletally immature patients.

LEVEL OF EVIDENCE

Level I-therapeutic.

Injectable Nonsteroidal Anti-Inflammatory Drugs in Sport

OBJECTIVE

The primary objective of this article is to review the basic science of nonsteroidal anti-inflammatory drugs (NSAIDs), their clinical effects, indications, potential complications, and ethical issues associated with the use of injectable NSAIDs in the treatment of athletes. These objectives are presented taking into consideration the contemporaneous issues associated with the treatment of amateur and professional athletes.

DATA SOURCES

A nonformal review of the published medical literature and lay media focusing on the use of injectable NSAIDs in athletes was used for this article.

MAIN RESULTS

All NSAIDs work through the inhibition of the cyclooxygenase (COX) pathway (either one or both subtypes) to reduce inflammation and inhibit pain by reducing prostaglandin and thromboxane synthesis. Complications related to NSAID use involve primarily the gastrointestinal, renal, and cardiovascular systems through this COX pathway inhibition. Ketorolac is the only NSAID currently available in an injectable form. Despite its analgesic efficacy comparable with opioid medication, injectable ketorolac has the potential to cause bleeding in collision athletes resulting from impaired hemostasis.

CONCLUSIONS

Nonsteroidal anti-inflammatory drug medications are currently used at every level of competition. Injectable ketorolac is an effective analgesic and anti-inflammatory drug. However, its potential effectiveness must be weighed against the risk of potential complications in all athletes, especially those who participate in contact/collision sports. The team physician must balance the goal of treating pain and inflammation with the ethical implications and medical considerations inherent in the administration of injectable medications solely to prevent pain and/or return the athlete to competition.

Effect of COX-2 inhibition on tendon-to-bone healing and PGE2 concentration after anterior cruciate ligament reconstruction

BACKGROUND

Non-steroidal anti-inflammatory drugs are commonly used to reduce pain and inflammation in orthopaedic patients. Selective cyclooxygenase-2 (COX-2) inhibitors have been developed to minimize drug-specific side effects. However, they are suspected to impair both bone and tendon healing. The objective of this study is to evaluate the effect of COX-2 inhibitor administration on tendon-to-bone healing and prostaglandin E (PGE2) concentration.

METHODS

Thirty-two New Zealand white rabbits underwent reconstructions of the anterior cruciate ligaments and were randomized into four groups: Two groups postoperatively received a selective COX-2 inhibitor (Celecoxib) on a daily basis for 3 weeks, the two other groups received no postoperative COX-2 inhibitors at all and were examined after three or 6 weeks. The PGE2 concentration of the synovial fluid, the osseous integration of the tendon graft at tunnel aperture and midtunnel section, as well as the stability of the tendon graft were examined via biomechanic testing.

RESULTS

After 3 weeks, the PGE2 content of the synovial fluid in the COX-2 inhibitor recipients was significantly lower than that of the control group (p = 0.018). At the same time, the COX-2 inhibitor recipients had a significantly lower bone density and lower amount of new bone formation than the control group (p = 0.020; p = 0.028) in the tunnel aperture. At the 6-week examination, there was a significant increase in the PGE2 content within synovial fluid of the COX-2 inhibitor recipients (p = 0.022), whose treatment with COX-2 inhibitors had ended 3 weeks earlier; in contrast, the transplant stability decreased and was reduced by 37% compared to the controls.

CONCLUSIONS

Selective COX-2 inhibitors cause impaired tendon-to-bone healing, weaken mechanical stability and decrease PGE2 content of the synovial fluid. The present study suggests a reluctant use of COX-2 inhibitors when tendon-to-bone healing is intended.

Do Nonsteroidal Anti-Inflammatory Drugs Cause Endoprosthetic Loosening? Mid- to Long-Term Follow-Up of 100 Total Hip Arthroplasties after Local NSAID Infiltration

We evaluated the effect of local infiltration of NSAIDs on prosthetic fixation at mid- to long-term follow-up of total hip arthroplasties. Intra-articular local NSAID (ketorolac) was injected into hip joints and surrounding tissues intraoperatively and postoperatively as a part of multimodal pain management protocol. Clinical and radiographic evaluation was performed for any evidence of component loosening or failure and clinical outcomes in 100 total hip joint arthroplasties with a mean follow-up of 7.3 years (4.9 to 11 yrs). Radiographic analysis at the most recent follow-up showed no evidence of loosening, subsidence, or migration and no evidence of impending failure. Clinical outcomes showed improved Harris hip scores. Intra-articular NSAID used in the intraoperative/postoperative period in hip arthroplasty showed no evidence of prosthetic loosening at mid- to long-term follow-up.

Ketorolac administration does not delay early fracture healing in a juvenile rat model: a pilot study

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective at controlling pain in children, especially in the treatment of fractures. Adult animal and adult clinical studies demonstrate conflicting evidence for the inhibitory relationship between NSAIDs and fracture healing. Published pediatric orthopaedic clinical studies do not demonstrate an inhibitory effect of ketorolac on bone healing. Little is known about the effects of any NSAID on bone formation in juvenile animals. This study investigates the effects of the NSAID ketorolac on fracture healing in a juvenile rat model.

METHODS

Unilateral surgically induced and stabilized tibial shaft fractures were created in 45 juvenile (3 to 4 wk old) male Sprague-Dawley rats. Either ketorolac (5 mg/kg; n=24) or saline (0.9% normal saline; n=21) was then administered to the rats 6 d/wk by intraperitoneal injections. Animals were then randomly assigned into time groups and euthanized at 7 days (n=8 ketorolac, n=7 saline), 14 days (n=8 ketorolac, n=7 saline), or 21 days (n=8 ketorolac, n=7 saline) postfracture. Biomechanical analysis was performed using a custom-designed 4-point bending loading apparatus. Statistics for tibial stiffness and strength data were performed using software package Systat 11. Specimens were also evaluated histologically using hematoxylin and eosin staining.

RESULTS

Strength and stiffness of all fractured tibiae increased over time from day 7 to day 21 regardless of treatment type. No statistical difference was found between the fractured tibiae strength or stiffness in the ketorolac or control-treated specimens at the same time point. In addition, the quality of the fracture callus was similar in both groups at each of the time points.

CONCLUSIONS

In this study of a juvenile rat model with a stabilized tibia fracture, fracture callus strength, stiffness, and histologic characteristics were not affected by the administration of ketorolac during the first 21 days of fracture healing.

CLINICAL RELEVANCE

The absence of inhibitory effects of ketorolac on early juvenile rat fracture healing supports the clinical practice of utilizing NSAIDs for analgesia in children with long bone fractures.

The growing role of eicosanoids in tissue regeneration, repair, and wound healing

Tissue repair and regeneration are essential processes in maintaining tissue homeostasis, especially in response to injury or stress. Eicosanoids are ubiquitous mediators of cell proliferation, differentiation, and angiogenesis, all of which are important for tissue growth. Eicosanoids regulate the induction and resolution of inflammation that accompany the tissue response to injury. In this review, we describe how this diverse group of molecules is a key regulator of tissue repair and regeneration in multiple organ systems and biologic contexts.

Anti-inflammatory treatment increases angiogenesis during early fracture healing

OBJECTIVES

Both inflammation and angiogenesis are crucial for normal fracture healing. The goal of this work was to determine how anti-inflammatory treatment affects angiogenesis during early stages of fracture repair.

METHODS

Tibia fractures were created in adult mice and animals were treated with indomethacin (2 mg/kg/day), a non-steroidal anti-inflammatory drug, or PBS once a day beginning from 1 day before fracture and continuing to 6 days after fracture. Animals were killed at 7, 14, and 28 days after injury for histomorphometric analysis of fracture healing. A second group of animals were killed at 3 and 7 days after injury to measure tissue levels of VEGF and interleukin-1 beta (IL-1β). A third group of animals were killed at 3 and 7 days after injury for stereology analysis of macrophage and neutrophil infiltration and tissue vascularization.

RESULTS

Indomethacin significantly decreased bone and cartilage formation at 7 days after fracture compared to controls. Indomethacin decreased the tissue levels of IL-1β at 3 days after fracture but did not affect the recruitment of macrophages or neutrophils to injured limbs. Indomethacin-treated fractures had similar length density and surface density of vasculature as the controls at 3 days after injury. At 7 days after fracture, vasculature in indomethacin-treated fractures exhibited higher length density and surface density than that in controls. By 28 days after injury, indomethacin-treated fractures still exhibited defects in fracture repair.

CONCLUSIONS

Anti-inflammatory treatments using indomethacin impair bone and cartilage formation and increase tissue vascularization in the callus during early fracture healing.

Do nonsteroidal anti-inflammatory drugs affect bone healing? A critical analysis

Nonsteroidal anti-inflammatory drugs (NSAIDs) play an essential part in our approach to control pain in the posttraumatic setting. Over the last decades, several studies suggested that NSAIDs interfere with bone healing while others contradict these findings. Although their analgesic potency is well proven, clinicians remain puzzled over the potential safety issues. We have systematically reviewed the available literature, analyzing and presenting the available in vitro animal and clinical studies on this field. Our comprehensive review reveals the great diversity of the presented data in all groups of studies. Animal and in vitro studies present so conflicting data that even studies with identical parameters have opposing results. Basic science research defining the exact mechanism with which NSAIDs could interfere with bone cells and also the conduction of well-randomized prospective clinical trials are warranted. In the absence of robust clinical or scientific evidence, clinicians should treat NSAIDs as a risk factor for bone healing impairment, and their administration should be avoided in high-risk patients.

Acute postoperative pain management in the older patient

Acute pain management in the older adult is both challenging and rewarding. This review addresses the difficulty with assessment of pain in the older adult, variations in the pain experience of older adults, physiological differences between the young and old, changes in pharmacokinetics and pharmacodynamics with age, and useful pharmacological treatments for acute pain in older adults. It then presents a few representative cases of pain management in older adults. The goal of this review is to provide relevant information that can be used to manage acute postoperative pain in the older adult.

Prolonged endochondral bone healing in senescence is shortened by low-intensity pulsed ultrasound in a manner dependent on COX-2

To test whether mechanical loading produces faster healing in aged mice, fractured femurs of aged 1-year-old mice were subjected to low-intensity pulsed ultrasound (LIPUS), a treatment that is routinely used to help heal fractures in humans. Cyclooxygenase-2 knockout mice (COX-2(-/-)), which lack an immediate early mediator of mechanical stimulation, were also studied by histochemistry, microcomputed tomography and quantitative polymerase chain reaction to determine the role of COX-2. The healing in the aged COX-2(-/-) mice is slow during the endochondral bone remodeling (>30 d), a period generally prolonged in senescence. For aged wild-type mice, LIPUS halved the endochondral phase to about 10 d, whereas that was not the case for aged COX-2(-/-) mice, which showed no apparent shortening of the prolonged endochondral-phase healing time. Injecting prostaglandin E(2) receptor agonists, however, rescued the COX-2(-/-) callus from insensitivity to LIPUS. In conclusion, COX-2 is a limiting factor in the delayed endochondral bone healing and is induced by LIPUS, which normalizes healing rate to the wild-type level.

Effect of Non-Steroidal Anti-Inflammatory Drugs on Bone Healing

Nonspecific and COX-2 selective nonsteroidal anti-inflammatory drugs (NSAIDs) function by inhibiting the cyclooxygenase isoenzymes and effectively reduce pain and inflammation attributed to acute or chronic musculoskeletal pathologies. However, use of NSAIDs as an analgesic is thought to negatively contribute to bone healing. This review strived to provide a thorough unbiased analysis of the current research conducted on animals and humans regarding NSAIDs and their effect on bone healing. Specifically, this review discusses the role of animal models, dosing regiments, and outcome parameters when examining discrepancies about NSAIDS and their effects on bone regeneration. The role of COX-2 in bone regeneration needs to be better defined in order to further elucidate the impact of NSAIDs on bone healing.

Soft tissue injections in the athlete

BACKGROUND

Injections into or adjacent to soft tissue structures, including muscle, tendon, bursa, and fascia, for pain relief and an earlier return to play have become common in the field of sports medicine.

STUDY DESIGN

Clinical review.

RESULTS

Corticosteroids, local anesthetics, and ketorolac tromethamine (Toradol) are the most commonly used injectable agents in athletes. The use of these injectable agents have proven efficacy in some disorders, whereas the clinical benefit for others remain questionable. All soft tissue injections performed for pain control and/or an anti-inflammatory effect have potentially serious side effects, which must be considered, especially in the pregame setting.

CONCLUSIONS

The primary concern regarding corticosteroid and local anesthetic injections is an increased risk of tendon rupture associated with the direct injection into the tendon. Intramuscular Toradol injections provide significant analgesia, as well as an anti-inflammatory effect via its inhibitory effect on the cyclooxygenase pathway. The risk of bleeding associated with Toradol use is recognized but not accurately quantified.

Ketorolac and spinal fusion: does the perioperative use of ketorolac really inhibit spinal fusion?

STUDY DESIGN

Retrospective review.

OBJECTIVE

To evaluate the effect of postoperative use of ketorolac (Toradol) on spinal fusion in humans.

SUMMARY OF BACKGROUND DATA

The value of parenteral ketorolac in postoperative analgesia has been well documented across surgical specialties. However, some studies have shown that ketorolac may adversely affect osteogenic activity and fracture healing.

METHODS

A total of 405 consecutive patients who underwent primary lumbar posterolateral intertransverse process fusion with pedicle screw instrumentation were included in this retrospective study. A subtotal of 228 patients received Toradol after surgery for adjunctive analgesia. Each patient received a mandatory dose of 30 mg intravenously every 6 hours for 48 hours. The same surgeon performed the fusion procedure on all of these patients. Historical controls included 177 patients who did not receive Toradol after surgery. The minimum follow-up period was 24 months. Nonunions were diagnosed by analyzing sequential radiographs, flexion-extension radiographs, and computed tomography with multiplanar reconstructions. The gold standard of surgical exploration was performed in symptomatic patients with diagnostic ambiguity or nonunions diagnosed by imaging.

RESULTS

There were no smokers in the study population. Pseudarthrosis was identified in 12 of 228 patients (5.3%) who received Toradol after surgery, and in 11 of 177 patients (6.2%) who did not. There was no significant difference detected in the nonunion rates between the two groups (P > 0.05, chi2 method).

CONCLUSION

Use of ketorolac after spinal fusion surgery in humans, limited to 48 hours after surgery for adjunctive analgesia, has no significant effect on ultimate fusion rates.

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.

The effect of ketoprophen on lumbar spinal fusion healing in a rabbit model. Laboratory investigation

OBJECT

Several reports have shown that nonsteroidal antiinflammatory drugs (NSAIDs) have an inhibitory effect in osteogenesis and reduce heterotopic ossification in humans. A deleterious effect of NSAIDs in posterolateral intertransverse process fusion has also been suggested. The authors used a validated rabbit model to try to determine the influence of the NSAID ketoprophen on the fusion rate in lumbar spinal arthrodesis.

METHODS

Thirty New Zealand male rabbits underwent posterolateral (intertransverse process) bilateral spinal fusions at a single level, using autologous bone graft obtained from both iliac crests. The animals were randomized after the operation, so that 15 rabbits received ketoprophen as a postoperative analgesic and the other 15 received the postoperative analgesic tramadol. The animals were killed 8 weeks after surgery, and fusion status was determined by inspection, palpation, anteroposterior radiographs, and histological analysis.

RESULTS

A solid fusion was obtained in eight rabbits (53%), and pseudarthrosis in seven rabbits (47%) in each group.

CONCLUSIONS

These findings suggest that the use of ketoprophen after intertransverse spinal fusion at a single level does not decrease the fusion rate, compared with tramadol.

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.

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.

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.

Early changes in prostaglandins precede bone formation in a rabbit model of heterotopic ossification

We have tested the hypothesis that the formation of heterotopic ossification (HO) in a rabbit model is correlated with a local increase in specific prostaglandins that may modulate mechanisms of ossification. Rabbits were sacrificed at 1 to 21 days following the daily forcible flexion of immobilized knees. The extraction and analysis of prostaglandins (PG) E2, F2alpha, D2, 6-keto-F1alpha, and thromboxane B2 in vastus intermedius muscles of manipulated legs revealed increases compared to control hindlimbs for all five prostaglandins, albeit of differing magnitude. The earliest increase was observed for PGF2alpha after 24 h (to 2.6-fold of control) with peak levels observed at day ten (185-fold of control). PGE2 was increased above control from 2 to 21 days following manipulation, with a peak level of 33-fold of control after 10 days. In a separate arm of the study, the role of PGE2 was investigated through the use of pharmacological antagonist of the PGE2 receptors and one of its second messengers, cAMP. Rabbits were preadministered the PGE2/PGD receptor antagonist AH 6809 or the cAMP antagonist Rp-cAMP prior to undergoing the regimen of limb immobilization and passive exercise. Both AH 6809 and Rp-cAMP were found to prevent the later development of radiographically documented heterotopic ossification in 15 out of 16 animals, thus identifying prostaglandins as being required for the development of ectopic bone. In this latter group, all but one pharmacologically treated animal showed an absence of HO at 3, 4, 5, or 6 weeks. These findings suggest an obligate cascade of prostaglandins for HO that offers the potential for novel prophylactic therapies, including those that target receptors for specific prostaglandins.

Practical management: nonsteroidal antiinflammatory drug (NSAID) use in athletic injuries

Nonsteroidal antiinflammatory drugs (NSAIDs) are frequently used in the treatment of acute athletic injuries, often for analgesic purposes as the evidence to support enhanced healing is limited. However, the current evidence on NSAID use in athletic injury is slowly growing. On the basis of animal models and limited human studies, some practical management guidelines can be drawn to assist the sports physician. Specifically, NSAIDs are not recommended in the treatment of completed fractures, stress fractures at higher risk of nonunion, or in the setting of chronic muscle injury. The only exception may be very short-term use (eg, a few days) for analgesic purposes only. Judicious use of NSAIDs may be more appropriate in the management of acute ligament sprains, muscle strains, tendinitis, and eccentric muscle injury. However, length of treatment should always be kept as short as possible, with consideration of the specific type of injury, level of dysfunction, and pain.

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.

Osteopenia and impaired fracture healing in aged EP4 receptor knockout mice

The EP4 receptor, one of the subtypes of the prostaglandin E2 (PGE2) receptor, plays a critical role in the anabolic effects of PGE2 on bone. However, its role in the maintenance of bone mass in aged animals and its role in fracture healing is not well known. Our studies addressed these issues by characterizing the skeletal phenotype of aged, EP4 receptor knockout (KO) mice, and by comparing fracture healing in aged KO mice versus wild type (WT) mice. There was no significant difference in body weight and femoral length between KO and WT mice at 15 to 16 months of age. Lower bone mass was seen radiographically in both axial and long bones of KO mice relative to WT mice. Micro-CT images of the distal femurs showed thinner cortices, fewer trabeculae, and a deteriorated trabecular network in KO mice. Total bone content, trabecular content, and cortical content, as assessed by pQCT in the distal femur, were lower in KO mice than WT controls. Histomorphometric measurements showed that trabecular bone volume and bone formation rate were significantly decreased whereas osteoclast number on trabecular surface and eroded surface on endocortical surface were significantly increased in KO mice. These data indicated that deleting the EP4 receptor resulted in an imbalance in bone resorption over formation, leading to a negative bone balance. The lower bone formation rate in EP4 KO mice was primarily due to decreased mineralizing surface, suggesting that the defect in overall bone formation was mainly due to the defect in osteoblastogenesis. Fracture healing was examined in KO and WT mice subjected to a transverse femoral fracture. Callus formation was significantly delayed as evidenced both radiographically and histologically in the fractured femurs of KO mice compared with those of WT mice. KO mice had significant decreases in total callus area, cartilaginous callus area, and bony callus area 2 weeks after fracture. By 4 weeks, complete bony bridging was seen in WT mice but not in KO mice. These data demonstrate that the absence of the EP4 receptor decreases bone mass and impairs fracture healing in aged male mice. Our findings indicate that the EP4 receptor is a positive regulator in the maintenance of bone mass and fracture healing.

Do non-steroidal anti-inflammatory drugs adversely affect stress fracture healing? A short review

A literature search was performed to determine whether non-steroidal anti-inflammatory drugs (NSAIDs) adversely affect the healing of stress fractures. Evidence exists from laboratory studies and animal subjects that NSAIDs can affect fracture healing. This link has not been proved or disproved in human subjects, particularly for stress fractures. In view of the high usage of NSAIDs in treating musculoskeletal disorders, research is required to investigate whether the healing of stress fractures is affected by these drugs.

The effect of nonsteroidal anti-inflammatory agents on spinal fusion

A large body of information suggests NSAIDS have a negative impact on the healing of bone. Although each clinical healing scenario presents a slightly different level of challenge, the healing of a posterolateral spinal fusion is one of the most difficult challenges in bony healing. Clinically, this results in a relatively high rate of nonunions using traditional fusion techniques. Spinal fusion models have confirmed NSAIDS have a definite inhibitory effect on healing of the fusion. Although data are limited, it appears this effect is most severe when NSAIDS are administered in the early postoperative period. Moreover, the effect may be worse with certain types initial inflammatory, subsequent reparative, and final remodeling phases. Because of the anti-inflammatory activity of NSAIDS, one might assume their effects would be worse when administered in the inflammatory phase. Indeed, the study by Riew et al suggests the inhibitory effects are more significant when NSAIDS are administered earlier following fusion. Other studies conducted with non-spinal models also suggest early administration of NSAIDS results in greater inhibition of bone formation (Goodman et al). Unfortunately, the length of the inflammatory phase in humans is not well known. This leaves the clinician unsure about the safe time to allow resumption of NSAID usage clinically. It appears likely NSAID use following a spinal fusion procedure will increase the rate of pseudarthrosis. The literature suggests that avoidance of NSAIDS in the postoperative period may avoid nonunion. Additionally, we propose that chronic NSAID usage should be addressed in a similar manner to cigarette smoking. While neither are absolute contraindications to elective spinal fusion, patients should be counseled to discontinue the use of NSAIDS in the peri- and postoperative period to maximize their chance for a successful fusion.

Effect of COX-2-specific inhibition on fracture-healing in the rat femur

BACKGROUND

Nonsteroidal anti-inflammatory medications have been shown to delay fracture-healing. COX-2-specific inhibitors such as celecoxib have recently been approved for human use. Our goal was to determine, mechanically, histologically, morphologically, and radiographically, whether COX-2-specific inhibition affects bone-healing.

METHODS

A nondisplaced unilateral fracture was created in the right femur of fifty-seven adult male rats. Rats were given no drug, indomethacin (1 mg/kg/day), or celecoxib (3 mg/kg/day) daily, starting on postoperative day 1. Fractures were analyzed at four, eight, and twelve weeks after creation of the fracture. Callus and bridging bone formation was assessed radiographically. The amounts of fibrous tissue, cartilage, woven bone, and mature bone formation were determined histologically. Morphological changes were assessed to determine fibrous healing, callus formation, and bone-remodeling. Callus strength and stiffness were assessed biomechanically with three-point bending tests.

RESULTS

At four weeks, only the indomethacin group showed biomechanical and radiographic evidence of delayed healing. Although femora from rats treated with celecoxib appeared to have more fibrous tissue than those from untreated rats at four and eight weeks, radiographic signs of callus formation, mechanical strength, and stiffness did not differ significantly between the groups. By twelve weeks, there were no significant differences among the three groups.

CONCLUSIONS

Postoperative administration of celecoxib, a COX-2-specific inhibitor, did not delay healing as seen at twelve weeks following fracture in adult rat femora. At four and eight weeks, fibrous healing predominated in the celecoxib group as compared with the findings in the untreated group; however, mechanical strength and radiographic signs of healing were not significantly inhibited.

CLINICAL RELEVANCE

Many orthopaedists rely on narcotic analgesia for postfracture and postoperative pain, despite deleterious side effects and morbidity. Traditional nonsteroidal anti-inflammatory medications have been shown to delay fracture union. This effect may be smaller with COX-2-specific inhibitors.

A novel, non-prostanoid EP2 receptor-selective prostaglandin E2 agonist stimulates local bone formation and enhances fracture healing

CP-533,536, a newly discovered, non-prostanoid EP2 receptor-selective PGE2 agonist, stimulates local bone formation and enhances fracture healing in rat models.

INTRODUCTION

There is a significant medical need for agents that can stimulate local bone formation and enhance fracture healing. We tested the effects of CP-533,536, a newly discovered, non-prostanoid EP2 receptor-selective prostaglandin E2 (PGE2) agonist, in stimulating local bone formation and enhancing fracture healing in rat models.

MATERIALS AND METHODS

In the first model, a single injection of CP-533,536 at doses of 0.3, 1, or 3 mg/kg to the proximal tibial metaphysis of 6-week-old male rats was given on day 1, and the local bone anabolic effect was determined on day 7. We then tested the effects of this compound in inducing bone formation on rat periosteum of the femur. A single dose of 0.3 mg of CP-533,536 incorporated in a poly-(D,L-lactide-co-glycolide) (PLGH) matrix was injected onto the periosteum of the femur in 3-week-old male rats, and local bone formation was determined on day 14. Finally, the ability of CP-533,536 in PLGH matrix in enhancing fracture healing was tested using the rat femoral fracture model. CP-533,536 in PLGH matrix at doses of 0.05, 0.5, or 5 mg was delivered to the local fracture site on the same day of fracture, and its efficacy was evaluated on day 21.

RESULTS AND CONCLUSIONS

A single injection of CP-533,536 at doses of 0.3, 1, or 3 mg/kg to the proximal tibial metaphysis dose-dependently stimulated local lamellar bone formation on trabecular, endocortical, and periosteal surfaces, and thus increased bone mineral content and bone strength at the injected site. Similarly, a single injection of 0.3 mg of CP-533,536 incorporated in PLGH matrix onto the periosteum of the femur induced significantly local bone formation. In the rat femoral fracture model, CP-533,536 in PLGH matrix at doses of 0.05, 0.5, and 5 mg dose-dependently increased callus size, density, and strength compared with PLGH matrix alone. These results show that CP-533,536 stimulates new bone formation on trabecular, endocortical, and periosteal surfaces and enhances fracture healing. These data reveal that EP2 receptor-selective agonists provide therapeutic potential for local bone augmentation, bone repair, and bone healing in humans.

Cyclooxygenase-2 inhibitors and nonsteroidal anti-inflammatory drugs in the management of arthritis

The management of arthritis pain should be individualized to the needs and characteristics of the patient. The decision to use nonsteroidal anti-inflammatory drugs (NSAIDs), and in particular the cyclooxygenase-2 (COX-2) inhibitors, is multidimensional. The challenge is to achieve optimal pain relief at the minimum dose to minimize adverse effects. Whenever possible, NSAIDs should be given as monotherapies or in combinations at the lowest effective doses. The COX-2 inhibitors are a safe choice for most patients who are at low risk for a cardiovascular event. Individuals who are at risk for thromboses should not receive unopposed COX-2 inhibitors; COX-2 should be given in combination with low-dose aspirin which is expected to be cardioprotective in high-risk patients.

Effect of tenoxicam on fracture healing in rat tibiae

BACKGROUND

Nonsteroidal anti-inflammatory drugs have been implicated in the development of delayed unions and nonunion after fractures in animal models. Previous investigations have identified two important factors as determinants of delayed fracture healing: early drug administration and a dose-dependent effect.

OBJECTIVE

The purpose of this investigation was to study the effect of tenoxicam, a nonsteroidal anti-inflammatory drug, on the fracture healing process in rat tibiae.

METHODS

Fifty-eight Wistar rats were randomly divided in four groups (I, II, III, and IV). Group I (control group, n=12) was given 0.1ml saline solution per day intramuscularly. Groups II (n=12), III (n=12), and IV (n=12) were administered 10mg per kg per day of tenoxicam intramuscularly. Administration of substances was begun on a week before to 48h after the fracturing procedure and continued during the entire experiment. Callus formation was studied histologically and histomorphologically, using light microscopy. In addition, a histologic grading based on the morphologic stage of fracture healing was carried out at 4 weeks, according to the criteria proposed by Allen et al.

RESULTS

There was a significant difference in treatment effect between Group I (saline solution) and Groups II, III, and IV (tenoxicam) (P=0.07). Histologically and histomorphologically, there were qualitative and quantitative delay in callus formation at all tenoxicam groups. This was more pronounced the earlier the nonsteroidal anti-inflammatory drug was started, although no significant difference could be detected between Groups II, III, and IV (P>(alpha=10%)). Four weeks after fracture, Group I (n=3) showed complete osseous union, Groups II (n=3) and III (n=3), complete cartilaginous union, and Group IV (n=3), incomplete osseous union, according to Allen et al. By using this rating scale, the difference between control and drug-treated groups was statistically significant (P<0.1).

CONCLUSION

Under studied conditions, this investigation shows that administration of tenoxicam intramuscularly delays fracture healing process in rat tibiae. These results suggest the hypothesis that early drug administration may delay bone healing after experimental fractures in animals, although it could not be detected statistically significant.

Cyclooxygenase-2 inhibitor inhibits the fracture healing

We investigated the effects of cyclooxigenase-2 (cox-2) on fracture healing. After closed non-displaced fractures were created at the middle of both femoral shafts in 12-week-old Wister rats, a cox-2 specific inhibitor, etodolac (20 mg/day; intra-peritoneal) was administered every day for three weeks (E group). Bone union and callus formation were evaluated by weekly radiographs. Three weeks after surgery, the mechanical strength of the fractured femur was evaluated by a three-point-bending test. These results were compared with those of a vehicle control group (V group). The fracture healing score on radiographs in the E group three weeks after the surgery was 3.3 +/- 0.9, and in the V group it was 5.8 +/- 1.5, indicating that fracture healing was significantly poorer in the E than the V group (p < 0.05). From the three point bending test, the ultimate strength and stiffness of etodolac-treated fractured femurs were shown to be significantly lower than those in vehicle control group (p < 0.05). Mechanically, femurs of etodolac treated rats were weaker than those of control rats. Thus, it was concluded that etodolac, a cox-2 specific inhibitor, inhibited fracture healing.

Nonsteroidal anti-inflammatory drugs and bone metabolism in spinal fusion surgery: a pharmacological quandary

The use of nonsteroidal anti-inflammatory drugs (NSAIDs) is ubiquitous in contemporary medical practice and these agents are efficacious in a number of clinical contexts. In particular, NSAIDs have proven to be highly effective adjuncts in the amelioration of postoperative pain in the subset of patients undergoing spinal surgery requiring fusion. NSAIDs act through inhibition of cyclooxygenase enzymes and therefore diminish prostaglandin production. However, prostaglandins are intimately involved in the modulation of bone metabolism and the balance of data, from both clinical and laboratory contexts, indicate that prostaglandins preferentially favor bone anabolism. Most recently, limited emerging evidence suggests that NSAID administration in patients undergoing spinal fusion surgery may increase nonunion rates, which in turn, has important ramifications to the patient, their family and the entire medical system. Hence, disparate views have evolved regarding the use of NSAIDs in postoperative pain control in patients undergoing spinal surgery requiring fusion. NSAIDs have proven efficacy in the management of postoperative pain in these patients, however, this must be weighed against the risk of nonunion and its associated consequences. In this review, the role of prostaglandins in bone metabolism, the pharmacology of NSAIDs and the modulation of bone metabolism by NSAIDs are discussed. Additionally, the current evidence examining the use of NSAIDs in spinal surgery is presented. As rates of spinal surgery continue to rise, it is imperative that the apparent pharmacological quandary surrounding the administration of NSAIDs in patients undergoing spinal surgery requiring fusion be addressed, both to guide present clinical practice and to outline further directions for investigation.

The effect of postoperative nonsteroidal anti-inflammatory drug administration on spinal fusion

STUDY DESIGN

The influence of ketorolac on spinal fusion was studied in a retrospective review of 288 patients who underwent an instrumented spinal fusion.

OBJECTIVE

To assess the effect of postoperative ketorolac administration on subsequent fusion rates.

SUMMARY OF BACKGROUND DATA

Nonsteroidal anti-inflammatory drugs are widely used compounds, which are known to inhibit osteogenic activity and have been shown to decrease spinal fusion in an animal model. No previous studies have examined the influence of nonsteroidal anti-inflammatory drugs on spinal fusion in clinical practice.

METHODS

The medical records of 288 patients who underwent instrumented spinal fusion from L4 to the sacrum between 1991 and 1993 were reviewed retrospectively. The 121 patients who received no nonsteroidal anti-inflammatory drugs were compared with the 167 patients who received ketorolac after surgery. The groups were demographically equivalent.

RESULTS

Ketorolac had a significant adverse effect on fusion, with five nonunions in the nondrug group and 29 nonunions in the ketorolac group (P > 0.001). Ketorolac administration also significantly decreased the fusion rate for subgroups including men, women, smokers, and nonsmokers. The odds ratio demonstrated that nonunion was approximately five times more likely after ketorolac administration. Cigarette smoking also decreased the fusion rate (P > 0.01); smokers were 2.8 times more likely to develop nonunion.

CONCLUSION

These data suggest that nonsteroidal anti-inflammatory drugs significantly inhibit spinal fusion at doses typically used for postoperative pain control. The authors recommend that these drugs be avoided in the early postoperative period.

Long-term treatment of indomethacin reduces vertebral bone mass and strength in ovariectomized rats

We investigated the effect of the long-term treatment of indomethacin, on lumbar spinal bone mineral density (LSBMD), cancellous bone mass, structure, and strength of vertebral body in old ovariectomized (OVX) rats. Ten-month-old female Wistar rats were divided into five groups: the sham operated + vehicle (sham + VEH) group, the OVX + vehicle (OVX + VEH) group, the OVX + indomethacin (IN) 1.5 mg/kg/week (OVX + IN1.5) group, the OVX + IN 6.0 mg/kg/week (OVX + IN6.0) group, and the OVX + IN 15.0 mg/kg/week (OVX + IN15.0) group. IN or vehicle were given by subcutaneous injection (s.c.) three times per week. The treatments were started at 1 week after operation and continued for 24 weeks. LSBMD (L2-L5) was measured at 0, 12, and 24 weeks after the beginning of treatment. At the end of the experimental period, the animals were sacrificed, and bone histomorphometrical and biomechanical analysis of lumbar vertebral body were done. LSBMD, trabecular bone volume (BV/TV), and trabecular thickness (Tb.Th) decreased significantly in a dose-related manner with IN. In the OVX + IN15.0 group, LSBMD decreased by 12.7%, BV/TV decreased by 65.5%, and Tb.Th decreased by 32.8%, compared with the OVX + VEH group. In addition, the maximum stress in a compressive mechanical test of L4 vertebral body in OVX groups was also decreased in a dose-related manner with IN, and this value in the OVX + IN15.0 group was 31.3% lower than in the OVX + VEH group. We conclude that long-term treatment with IN accentuated the OVX-related decrease in trabecular bone mass and the compressive strength of lumbar vertebrae.

The effects of nonsteroidal anti-inflammatory drugs on posterior spinal fusions in the rat

STUDY DESIGN

This was a prospective study to determine the potential effects of indomethacin on spinal fusions in the rat.

OBJECTIVES

To determine if indomethacin exerts a deleterious effect on spinal fusions in the rat model.

SUMMARY OF BACKGROUND DATA

Nonsteroidal anti-inflammatory drugs are a class of compound that affect bone osteogenesis during fracture healing and heterotopic ossification. Spinal fusion is a process that occurs via osteogenesis and, therefore, may be similarly affected.

METHODS

Thirty-nine adult, Sprague-Dawley rats underwent a three-level posterior spinal fusion. Fusion was performed using morselized autogenous vertebral bone graft obtained via caudectomy and stabilized using a cerclage wiring technique. The 39 rats were divided into two groups consisting of 17 study animals and 22 control animals. The control group was injected with 1.5 cc of 0.9 normal saline subcutaneously for 12 weeks, whereas the test animals were injected on an identical schedule using 3 mg/kg of indomethacin sodium salt. Two control animals died, and three animals in the treatment group died of drug-related complications. Twelve weeks after surgery, all animals were killed, and the involved spinal segments were evaluated by direct manual examination. A fusion was probable if the spinal segments exhibited decreased scaled micromotion.

RESULTS

Sixty segmental levels in 20 control animals were assessed. Overall, 27 of 60 levels (45%) achieved fusion. In the indomethacin-treated group, 42 levels in 14 animals were evaluated. Overall, four of 42 levels (10%) achieved a fusion. Chi-square analysis demonstrated a significant difference (P < 0.001) between the control and indomethacin-treated groups.

CONCLUSIONS

This study raises serious questions about the inhibitory effects of nonsteroidal anti-inflammatory drugs on spinal fusion. Clinically, the widespread use of nonsteroidal anti-inflammatory drugs in the postoperative period after spinal fusion may need to be avoided.

Effect of two nonsteroidal antiinflammatory drugs on heterotopic bone formation in a rabbit model

Using the model described by Michelsson, 24 mature New Zealand white rabbits underwent mechanical induction of heterotopic ossification in the quadriceps of the right hind limb. The rabbits were equally divided into four groups: indomethacin-treated, piroxicam-treated, and their respective controls. The effect of drug therapy on the production of heterotopic bone was assessed by analyzing plain radiographs of the femur using the grading system described by Scott. The results demonstrated that, while indomethacin is effective in decreasing the formation of heterotopic bone, piroxicam--when used in the dosage previously demonstrated to have no deleterious effect on healing bone--is not. The analysis of piroxicam blood levels demonstrated that the experimental piroxicam dose is inadequate to produce effective plasma blood levels in the rabbit. Therefore, any potential benefit from using piroxicam, as opposed to other nonsteroidal antiinflammatory drugs regarding fracture healing and bone remodeling, cannot be applied for the prophylactic treatment of heterotopic bone formation.

Fracture healing in rats inhibited by locally administered indomethacin

We studied the inhibitory effect of indomethacin on fracture healing in 135 young, male rats after oral administration compared with local application into the fracture. A closed mid-diaphyseal fracture of the left femur was performed in all the rats. The fractures were not immobilized. In one experiment, half of the animals received indomethacin via a stomach tube (2 mg/kg/day) for 10 days; the controls received only the vehicle. In another experiment, 0.5 mg of indomethacin, contained in a bioerodible polyorthoester gel, was injected into the fracture area in half the rats; in the controls, only the gel was injected. In both experiments, random animals were killed on Days 0, 5, 10, and 20. As assessed by radiographs and manual testing, the same inhibition of fracture healing was found regardless of whether indomethacin was given orally or locally. However, the amount of indomethacin that was applied locally was only one fourth of the total dose given orally; no indomethacin was detected in the serum.

The suppression of heterotopic ossification after total hip arthroplasty

In a double-blind prospective randomised study we examined the effects of Diclofenac on heterotopic ossification after hip arthroplasty. Either the drug, or a placebo, was given by mouth to 158 patients in doses of 3 x 50 mg for 6 weeks. Diclofenac resulted in highly significant improvement (p less than 0.0001 versus controls) without severe side-effects. Heterotopic ossification decreased from 55% in the placebo to 15%. Significant degrees of heterotopic ossification did not occur with the drug. Movement of the hip was considerably increased after operation. We recommend Diclofenac prophylaxis against heterotopic ossification after hip operations in view of the serious clinical effects of this complication and its quoted incidence of 15% to 80%.

Effects of indomethacin on demineralized bone-induced heterotopic ossification in the rat

Indomethacin inhibits bone formation when treatment is initiated before the implantation of demineralized bone matrix (DBM). For the inhibition of bone induction to occur, indomethacin treatment had to be initiated 6 h or more before implantation of DBM. Initiating the drug treatment at or after the time of DBM implantation had no effects on the amounts of new bone formed. The inhibition by indomethacin is dose related over a range between 0.04 and 4 mg/kg body weight. Recovered day-1 DBM implants, transplanted into indomethacin pre- and posttreated syngeneic rats, formed bone at the same rate as controls did. However, recovered day-1 DBM implants lyophilized before transplantation showed decreased bone formation but significant dystrophic calcification as judged by a lower alkaline phosphatase activity and an elevated calcium content.

Effect of naproxen on cancellous bone in ovariectomized rats

Nonsteroidal anti-inflammatory drugs (NSAIDs) affect bone metabolism in vitro and in vivo. They delay but do not alter the outcome of healing processes in bone. In some bone loss models, they block bone resorption and slow the rate of loss. We studied the effect of naproxen, a potent NSAID, on cancellous bone of the proximal tibial metaphysis of 6-month-old adult female ovariectomized rats. Animals were ovariectomized, divided into groups, and fed standard diets differing only in naproxen content for 42 days. The rats of the groups ate 2.0, 5.5, 12.7, and 32 mg naproxen per kg body weight per day, respectively. Serum levels of naproxen were determined. Bone volume, mineralizing surface, osteoblast activity, osteoclast surface, and bone resorption rate were determined by bone histomorphometric techniques. The rats' dose-related serum naproxen levels ranged from 4 to 28 micrograms/ml. Naproxen inhibited up to 70% of the bone loss occurring after ovariectomy at a serum level of 4 micrograms/ml. We deduced that naproxen blocked bone resorption in ovariectomized rats by slowing osteoclast activity at all doses. In contrast, naproxen slowed bone formation only at serum levels greater than 20 micrograms/ml in ovariectomized rats. These findings may have clinical relevance in helping to prevent postmenopausal bone loss in women.

Indomethacin and bone trauma. Effects on remodeling of rabbit bone

The influence of indomethacin on remodeling activity in normal trabecular and cortical bone and its influence on cortical bone close to a midtibial drill hole, 2 mm in diameter were histomorphometrically evaluated. Eight rabbits were treated with indomethacin (12.5 mg/kg/day), and another 8 rabbits served as controls. After 3 days, the mean plasma indomethacin level was 542 ng/mL, resulting in an almost complete inhibition of prostaglandin synthesis as reflected by the serum levels. In the control rabbits the remodeling activity after 6 weeks was increased 1 mm away from the drill hole but not at 3 and 8 mm. In conclusion, indomethacin had no effect on the activated remodeling process in cortical bone neighboring a small drill hole or on remodeling in nontraumatized cortical and cancellous bone. This suggests that the inhibitory effect of indomethacin on the remodeling process following local trauma to bone depends on the extent of the trauma.

Effects of phenylbutazone and indomethacin on the post-operative course following experimental orthopaedic surgery in dogs

Randomized placebo-controlled crossover studies were carried out in dogs to evaluate how two non-steroidal anti-inflammatory drugs (NSAID) might modulate an acute post-traumatic inflammatory reaction. Two "identical" surgical interventions were performed on the forelimbs of each animal with an interval of 28 days, to enable a paired comparison of the inflammatory signs and the wound/bone healing processes. At one operation 8 dogs received 300 mg phenylbutazone twice daily for 8 days starting on the day before surgery, and at the other operation matching placebo tablets were given. In a similar placebo-controlled trial another group of 8 dogs received 5 mg indomethacin twice daily. With phenylbutazone the post-operative swelling was not significantly reduced compared to placebo, but there was less pain and limping. With indomethacin the swelling was somewhat reduced, but there was no consistent difference to placebo in the pain and limping assessments. None of the drugs appeared to distinctly effect the wound or fracture healing, as evaluated by clinical inspection, comparison of radiographs and comparison of bone sections from the sites of surgery. It proved difficult to select an appropriate dosage of indomethacin due to its high potential to induce GI ulceration and bleeding in dogs. In this experimental surgical model with an acute inflammation, neither phenylbutazone nor indomethacin showed impressive anti-inflammatory or analgesic properties. In the same model paracetamol has proved to significantly and more efficiently, reduce both swelling and pain without any noticeable adverse effects, and appears to be a better alternative than the two presently tested NSAID.

Effects of indomethacin on bone ingrowth

The effects of indomethacin, a nonsteroidal antiinflammatory agent, on bone ingrowth were studied using a rabbit animal model and a porous cylindrical implant system. Bone ingrowth was found to be independent of pore size in the range tested (0.6-1.0 mm). In the control (placebo-treated) group, there was a significant increase in bone ingrowth between the 2- and 8-week groups of animals. However, in the indomethacin-treated group, there was no increase in bone ingrowth with time.

Indomethacin for the prevention of heterotopic ossification following total hip arthroplasty. Effectiveness, contraindications, and adverse effects

Seventy-four patients undergoing total hip arthroplasty considered to be at high risk for heterotopic ossification were given 75 mg of indomethacin daily for 6 weeks after operation and studied clinically and radiographically for a minimum of 6 months. Twenty-seven patients (37%) could not complete the drug course. Of the 47 (63%) patients completing treatment, only 2 (4%) had grade IIA (mild) and no patients had more severe heterotopic ossification. No major complications were attributed to the use of indomethacin. These findings support the evidence that indomethacin can effectively prevent higher grades of heterotopic ossification following total hip arthroplasty. However, approximately one-third of the patients were unable to complete the course of drug therapy, limiting the overall usefulness of indomethacin. Surgeons prescribing indomethacin must also be aware of its contraindications and adverse effects.

The influence of indomethacin on biomechanical and biochemical properties of the plantaris longus tendon in the rabbit

It has previously been reported that indomethacin inhibits fracture healing and heterotopic bone formation. Stimulated by these reports, we undertook the present investigation to study the influence of indomethacin on biomechanical and biochemical properties of the plantaris longus tendon in the rabbit. Sixty-eight New Zealand White rabbits were used for the experiment. Half of them were treated with indomethacin, 10 mg/kg orally a day, and the other half with placebo. After 4, 8, and 16 weeks of treatment biomechanical and biochemical variables were determined and compared between the two groups. After 16 weeks there was a significant increase in tensile strength in the group treated with indomethacin. There was no certain concomitant change in the total collagen content, the amounts of soluble and insoluble collagen, or the water content. Further investigations concerning the influence of indomethacin on tendon healing are indicated.

Indomethacin does not inhibit the anabolic effect of parathyroid hormone on the long bones of rats

Chronic administration of parathyroid hormone, hPTH 1-34, increased bone mass in normocalcemic, young rats. Since PTH can stimulate prostaglandin E2 (PGE2) production in bone in vitro, and since PGE2 can stimulate bone formation, the anabolic effect of PTH could be mediated by PGE2. To test this hypothesis, experiments were done to determine if indomethacin, which blocks endogenous PG production, would inhibit the anabolic response of bone to PTH. In the first experiment, male Sprague-Dawley rats, 70-100 g, in groups of five, were treated for 12 days with either hPTH 1-34, 8 micrograms/100g/day; PTH vehicle; indomethacin, 2 mg/kg/day; or a combination of PTH and indomethacin. In the second experiment, groups of 6 rats each were given vehicle or hPTH 1-34, 8 micrograms/100g/day, in combination with indomethacin, 0, 1, 2, or 4 mg/kg/day. Subcutaneous injections of PTH wee given once daily and indomethacin was given orally in divided doses, twice a day. Rats were killed on day 12 in both experiments; their sera were analyzed and the trabecular and cortical bone of distal femurs processed to determine calcium (Ca) and hydroxyproline content and dry weight. PTH and indomethacin had no significant effect on serum Ca, phosphate, alkaline phosphatase, urea nitrogen and creatinine, or systemic and long-bone linear growth. In rats treated with PTH alone or in combination with indomethacin, bone Ca of distal femurs increased by 28-44%; dry weight by 29-41%, and hydroxyproline by 17-45%. Indomethacin alone had no effect on bone growth.(ABSTRACT TRUNCATED AT 250 WORDS)