Low-magnitude whole body vibration does not affect bone mass but does affect weight in ovariectomized rats

Mechanical loading has stimulating effects on bone architecture, which can potentially be used as a therapy for osteoporosis. We investigated the skeletal changes in the tibia of ovariectomized rats during treatment with whole body vibration (WBV). Different low-magnitude WBV treatment protocols were tested in a pilot experiment using ovariectomized rats with loading schemes of 2 × 8 min/day, 5 days/week (n = 2 rats per protocol). Bone volume and architecture were evaluated during a 10 week follow-up using in-vivo microcomputed tomography scanning. The loading protocol in which a 45 Hz sine wave was applied at 2 Hz with an acceleration of 0.5g showed an anabolic effect on bone and was therefore further analyzed in two groups of animals (n = 6 each group) with WBV starting directly after or 3 weeks after ovariectomy and compared to a control (non-WBV) group at 0, 3, 6 and 10 weeks’ follow-up. In the follow-up experiment the WBV stimulus did not significantly affect trabecular volume fraction or cortical bone volume in any of the treatment groups during the 10 week follow-up. WBV did reduce weight gain that was induced as a consequence of ovariectomy. We could not demonstrate any significant effects of WBV on bone loss as a consequence of ovariectomy in rats; however, the weight gain that normally results after ovariectomy was partly prevented. Treatment with WBV was not able to prevent bone loss during induced osteoporosis.     

Absence of mouse pleiotrophin does not affect bone formation in vivo

Pleiotrophin (Ptn) is an extracellular matrix protein that regulates hippocampal synaptic plasticity and learning behavior in vivo. Since the overexpression of Ptn in transgenic mice leads to increased bone formation, we analyzed whether a deficiency in Ptn expression would have a negative effect on bone remodeling. Bones from Ptn-deficient mice and wild-type littermates were analyzed using radiography, μCT imaging and undecalcified histology. Biomechanical stability was determined in a three-point-bending assay. Cellular activities were assessed using dynamic histomorphometry and the determination of urinary collagen degradation products. Skeletons of Ptn-deficient mice have no gross abnormalities, displayed a normal size, and showed no differences in growth plate organization compared to wild-type littermates. There were no obvious differences in bone mass as determined by radiographic and μCT imaging. The absence of a bone remodeling phenotype in Ptn-deficient mice was further confirmed using static histomorphometry and biomechanical testing. Finally, the number, morphology, and function of osteoclasts, osteoblasts, and osteocytes were not altered in Ptn-deficient mice compared to wild-type littermates. The complete skeletal analysis of Ptn-deficient mice presented here demonstrates that the lack of Ptn in mice does not affect bone formation in vivo. Therefore, Ptn does not play a significant role in normal bone physiology.     

Disruption of glucocorticoid signaling in chondrocytes delays metaphyseal fracture healing but does not affect normal cartilage and bone development

States of glucocorticoid excess are associated with defects in chondrocyte function. Most prominently there is a reduction in linear growth but delayed healing of fractures that require endochondral ossification to also occur. In contrast, little is known about the role of endogenous glucocorticoids in chondrocyte function. As glucocorticoids exert their cellular actions through the glucocorticoid receptor (GR), we aimed to elucidate the role of endogenous glucocorticoids in chondrocyte function in vivo through characterization of tamoxifen-inducible chondrocyte-specific GR knockout (chGRKO) mice in which the GR was deleted at various post-natal ages. Knee joint architecture, cartilage structure, growth plates, intervertebral discs, long bone length and bone micro-architecture were similar in chGRKO and control mice at all ages. Analysis of fracture healing in chGRKO and control mice demonstrated that in metaphyseal fractures, chGRKO mice formed a larger cartilaginous callus at 1 and 2 week post-surgery, as well as a smaller amount of well-mineralized bony callus at the fracture site 4 week post-surgery, when compared to control mice. In contrast, chondrocyte-specific GR knockout did not affect diaphyseal fracture healing. We conclude that endogenous GC signaling in chondrocytes plays an important role during metaphyseal fracture healing but is not essential for normal long bone growth.     

Conditional deletion of BMP7 from the limb skeleton does not affect bone formation or fracture repair

While the osteoinductive activity of recombinant bone morphogenetic protein 7 (BMP7) is well established, evaluation of the role of endogenous BMP7 in bone formation and fracture healing has been hampered by perinatal lethality in BMP7 knockout mice. Here we employ conditional deletion of BMP7 from the embryonic limb prior to the onset of skeletogenesis to create limb bones lacking BMP7. We find that the absence of locally produced BMP7 has no effect on postnatal limb growth, articular cartilage formation, maintenance of bone mass, or fracture healing. Our data suggest that other BMPs present in adult bone are sufficient to compensate for the absence of BMP7. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:384–389, 2010     

Chemotherapy for bone sarcoma does not affect fertility rates or childbirth

There have been unprecedented improvements in the survival of patients with bone sarcomas because of advances in chemotherapy during the past two decades. However, along with improved survival, there have been concerns of gonadal toxicity and fertility. These problems with chemotherapy are well documented for conditions like lymphomas and testicular cancers. There are few reports on fertility outcomes with chemotherapy for bone sarcomas. The purpose of this study was to review the rate of successful conceptions, pregnancy outcomes, incidence of birth defects, and fertility rates in young adults who had chemotherapy for high-grade bone sarcomas. A retrospective chart review of all eligible patients was done. No laboratory assessment of fertility was done. Fifteen of the 36 patients attempted conceptions, and all were successful [corrected] One miscarriage occurred and one medical termination of pregnancy was done because of a spinal metastasis. There were 13 successful full-term pregnancies with no birth defects. The conception rate was 1.6. Despite the common misconception of probable infertility, these patients can have high expectations to conceive, with uneventful childbirth and no birth defects in the newborns. Although counseling should include the possibility of infertility, patients also should be reminded of the high rate of success of having a normal conception and childbirth.     

Experimental osteoporosis induced by ovariectomy and vitamin D deficiency does not markedly affect fracture healing in rats

BACKGROUND: The question of whether fracture healing and mechanical properties of the callus are influenced by osteoporosis (OP) is still not settled. We therefore studied this issue in vitamin D-depleted ovariectomized (OVX) rats, an OP model previously shown to induce weakening of the femoral neck, and thus thought to be closer to the human condition than the classic OVX rat model. METHODS: 72 female Wistar rats were randomized into two groups: ovariectomy and vitamin D-deficient diet (Ovx-D group) or sham operation and normal rat chow (Sham group). After 12 weeks, a closed tibial midshaft fracture was performed on the right side and fixed with an intramedullary nail. Bone loss and callus formation were monitored with DXA; serum levels of estradiol and vitamin D3 were measured and histomorphometric analyses were performed. Mechanical properties of callus, tibia, femoral shaft, and femoral neck were examined in 3-point cantilever bending 6 weeks after fracture. RESULTS: The Ovx-D group showed reduced BMD in the spine and femoral neck, and reduced trabecular bone volume in the femoral head. There were no differences in BMD and mechanical properties of callus between the groups. Except for reduced stiffness of the right femoral neck in the Ovx-D group (p = 0.02), no differences in the mechanical strength of long bones were detected. INTERPRETATION: Our results suggest that the systemic effects of estrogen and vitamin D deficiency are not crucial for fracture healing or mechanical properties of the callus.     

Etanercept does not impair healing in rat models of tendon or metaphyseal bone injury

Background and purpose

Should blockade of TNF-α be avoided after orthopedic surgery? Healing of injuries in soft tissues and bone starts with a brief inflammatory phase. Modulation of inflammatory signaling might therefore interfere with healing. For example, Cox inhibitors impair healing in animal models of tendon, ligament, and bone injury, as well as in fracture patients. TNF-α is expressed locally at increased levels during early healing of these tissues. We therefore investigated whether blocking of TNF-α with etanercept influences the healing process in established rat models of injury of tendons and metaphyseal bone.

Methods

Rats were injected with etanercept, 3.5 mg/kg 3 times a week. Healing of transected Achilles tendons and bone healing around screws implanted in the tibial metaphysis were estimated by mechanical testing. Tendons were allowed to heal either with or without mechanical loading. Ectopic bone induction following intramuscular BMP-2 implants has previously been shown to be stimulated by etanercept in rodents. This was now tested as a positive control.

Results

Tendon peak force after 10 days was not significantly influenced by etanercept. Changes exceeding 29% could be excluded with 95% confidence. Likewise, screw pull-out force was not significantly influenced. More than 25% decrease or 18% increase could be excluded with 95% confidence. However, etanercept treatment increased the amount of bone induced by intramuscular BMP-2 implants, as estimated by blind histological scoring.

Interpretation

Etanercept does not appear to impair tendon or metaphyseal bone healing to any substantial degree.Inflammation is an important part of early healing of both bone and soft tissues. Several inflammatory mediators are known to be expressed and to influence tissue healing. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenases and direct eicosanoid synthesis from prostaglandins towards leukotrienes (Cottrell and O’Connor 2009). It has been known for decades that these drugs inhibit fracture repair in animal models; later, it was shown that they also inhibit tendon and ligament healing (Elder et al. 2001, Virchenko et al. 2004). It has also been shown that NSAIDs increase the risk of healing complications in patients with high-energy fractures (Burd et al. 2003). Clinicians now take this into account and avoid using NSAIDs in cases where bone healing might become problematic. Corticosteroids inhibit fracture healing in animal experiments, possibly through its anti-inflammatory action (Waters et al. 2000, Doyon et al. 2010). Other drugs that modulate inflammatory mediators, such as modulators of tumor necrosis factor α (TNF-α) signaling, have not been studied much in the fracture healing context.TNF-α is expressed during fracture healing (Kon et al. 2001). Also, we have noted strong TNF-α expression during early tendon healing, and that mechanical loading can reduce this expression (Eliasson et al. 2009a). There are few data available on how modulation of TNF-α signaling influences repair. Systemic treatment with TNF-α was found to reduce the amount of cartilage formed in rib fractures in rats (Hashimoto et al. 1989), and antagonizing the effect of TNF-α with etanercept increased bone formation in bone morphogenic protein-2 (BMP-2) implants in mice (Eguchi et al. 2010). Mice unable to express TNF-α receptor p55/p75 have delayed cartilage resorption during endochondral fracture healing (Gerstenfeld et al. 2003). TNF-α signaling appears to be required for normal membranous ossification, as this type of bone formation is reduced in receptor knockout mice (Gerstenfeld et al. 2001). Recently, it was suggested that TNF-α was crucial for recruiting muscle-derived stem cells (MSCs) into fracture hematomas in a mouse delayed-union model (Glass et al. 2011). The same article also briefly described a positive effect on mouse tibial fracture healing of local injections of TNF-α on day 0 and 1 after fracture, as measured on day 28. Although studies with receptor knockouts or local injection of TNF-α can give mechanistic insights, they may not be ideal for predicting the effects of etanercept treatment.Clinically, fractures in metaphyseal bone, which heal mainly by membranous endosteal bone formation, are much more common than diaphyseal fractures, which heal partly by endochondral repair. Ruptures in soft collagenous tissues are also common. Because the in vivo functions of TNF-α appear complex, even a detailed knowledge of its effects at the cellular level is probably insufficient to be able to accurately predict the consequences of changing TNF-α signaling during a healing process. We therefore studied the effects of etanercept on tendon healing and endosteal membranous ossification in vivo using validated rat models, where the results of both of these processes can be tested mechanically.Short, early NSAID treatment can impair healing. It appears that early inflammation may be necessary to trigger healing, while late inflammation could be deleterious (Virchenko et al. 2004). We therefore tested etanercept treatment both in the early phase and later in separate groups. Because etanercept has been shown to increase bone formation in intramuscular BMP-2 implants (Eguchi et al. 2010), we used that model as a form of positive control to demonstrate that the etanercept regime was adequate.     

Hypochlorhydria‐induced calcium malabsorption does not affect fracture healing but increases post‐traumatic bone loss in the intact skeleton

Efficient calcium absorption is essential for skeletal health. Patients with impaired gastric acidification display low bone mass and increased fracture risk because calcium absorption is dependent on gastric pH. We investigated fracture healing and post‐traumatic bone turnover in mice deficient in Cckbr, encoding a gastrin receptor that affects acid secretion by parietal cells. Cckbr?/? mice display hypochlorhydria, calcium malabsorption, and osteopenia. Cckbr?/? and wildtype (WT) mice received a femur osteotomy and were fed either a standard or calcium‐enriched diet. Healed and intact bones were assessed by biomechanical testing, histomorphometry, micro‐computed tomography, and quantitative backscattering. Parathyroid hormone (PTH) serum levels were determined by enzyme‐linked immunosorbent assay. Fracture healing was unaffected in Cckbr?/? mice. However, Cckbr?/? mice displayed increased calcium mobilization from the intact skeleton during bone healing, confirmed by significantly elevated PTH levels and osteoclast numbers compared to WT mice. Calcium supplementation significantly reduced secondary hyperparathyroidism and bone resorption in the intact skeleton in both genotypes, but more efficiently in WT mice. Furthermore, calcium administration improved bone healing in WT mice, indicated by significantly increased mechanical properties and bone mineral density of the fracture callus, whereas it had no significant effect in Cckbr?/? mice. Therefore, under conditions of hypochlorhydria‐induced calcium malabsorption, calcium, which is essential for callus mineralization, appears to be increasingly mobilized from the intact skeleton in favor of fracture healing. Calcium supplementation during fracture healing prevented systemic calcium mobilization, thereby maintaining bone mass and improving fracture healing in healthy individuals whereas the effect was limited by gastric hypochlorhydria. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1914–1921, 2016.

     

Long-term administration of clodronate does not prevent fracture healing in rats

Clinicians have been concerned that fractures do not heal properly in individuals exposed to bisphosphonate treatment, a treatment that strongly affects bone metabolism. The current study attempted to clarify the long-term effects of clodronate (dichloromethylene bisphosphonate) treatment on fracture healing in growing rats. Clodronate was administered subcutaneously twice a week in a dose of 2 mg/kg or 10 mg/kg. Physiologic saline served as a control. After 24 weeks of treatment, the tibiae were fractured, and the treatment was continued for another 4 weeks and 8 weeks. At both end points the cross-sectional areas of the callus, measured by peripheral quantitative computed tomography, were greater in the clodronate-treated rats than in controls, but there were no significant differences in bone mineral density. There were no significant differences between treatments in radiologic healing, histomorphometry, or in mechanical failure load of the callus with the exception of increased tensile stiffness at a dose of 2 mg/kg at 4 weeks. Clodronate treatment does not seem to prolong the fracture healing process, even when administered on a long-term basis before the fracture. Clodronate increases the size of the callus, but has only a minor effect on its biomechanical properties. The current results suggest that long-term clodronate treatment does not inhibit fracture healing.     

Pinealectomy does not affect the healing of experimental colonic anastomoses.

Gastrointestinal system anastomoses, especially colonic anastomoses, have significant morbidity and mortality despite recent technical improvements. Besides regulating the circadian rhythm, the pineal gland and its main neurohormone product melatonin have widespread actions in the organism. The purpose of this study was to investigate the effects of pinealectomy on the healing of colonic anastomoses. One hundred male albino Wistar rats were used in this study. The rats were separated into three groups: control, pinealectomy, and sham groups. In the control group, only colonic resection and anastomoses were performed. Following pinealectomy, colonic anastomosis was performed 2 weeks later on one half and 2 months later on the other half of the pinealectomy group. Only craniotomy was performed on the sham group, and the rats were separated and evaluated like the pinealectomy group. Colonic anastomoses were evaluated on postanastomotic day 3 and 7 by measuring the bursting pressure and the hydroxyproline levels in the anastomotic segments. There was no difference in the bursting pressure measurements between the groups on both postoperative day 3 and 7. Although hydroxyproline levels were different between groups on both postanastomotic days 3 and 7, it has been observed that neither normal nor anastomotic hydroxyproline levels influenced the anastomotic bursting pressure measurements. The percent deviation from the normal values was compared in the anastomotic segments, and no differences were found regarding the bursting pressure and hydroxyproline levels. It was concluded that pinealectomy has no effect on the healing of colonic anastomoses.     

Subanesthetic sevoflurane does not affect sympathetic or parasympathetic function

To evaluate the effects of subanesthetic enflurane and sevoflurane on the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS), the blood level of norepinephrine (NE) and fluctuations in the R-R intervals were measured on electrocardiogram in humans given either 0.5 MAC enflurane or sevoflurane. Enflurane suppressed circulating plasma NE and elevated coefficients of variation (CV) of R-R intervals after 20 and 30 min of inhalation. In contrast, 0.5 MAC of sevoflurane slightly stimulated cardiovascular function without any change in blood NE. Sevoflurane lowered the CV to 84% of control after 30 min of inhalation. These results indicate that subanesthetic concentrations of sevoflurane are unlikely to perturb sympathetic and parasympathetic activities in humans without surgical stimulation when compared with enflurane.     

Vitamin K supplementation does not affect ovariectomy-induced bone loss in rats

Vitamin K may be important in bone metabolism. Notably, high-dose menaquinone-4 (menatetrenone, MK4) has been reported to reduce ovariectomy (ovx)-induced bone loss in rats and to decrease osteoporotic fracture in postmenopausal women. However, it is unclear whether these beneficial effects reflect a physiologic effect of vitamin K, or indicate direct pharmacologic activity of MK4. To further evaluate this, 60 6-month-old nulliparous Sprague-Dawley rats were randomized by distal femur bone mineral density (BMD) in a 3:1 ratio to ovx or sham groups. The sham and one ovx group’s diet contained 1% calcium and 1300 μg/kg of vitamin K1, phylloquinone. Diets of the other two ovx groups were supplemented with 882 mg phylloquinone or MK4 per kilogram chow. Distal femur bone mineral density (DFBMD) in an 8 mm region of interest was measured at baseline, 1 and 3 months postoperatively, utilizing dual-energy X-ray absorptiometry (DXA). All animals were killed at 3 months, their right femurs excised, ex vivo BMD measured by DXA, and biomechanical testing performed. No effect of phylloquinone or MK4 supplementation on ovx-induced bone loss was observed. Specifically, DFBMD declined 10.5%, 9.2%, and 11.2% at 1 month and 14.4%, 10.6%, and 13.9% at 3 months in the ovx control, high phylloquinone, and high MK4 groups, respectively. In addition, serum osteocalcin was elevated by ovx; this was not altered by phylloquinone or MK4. Finally, femoral biomechanical properties were not affected by phylloquinone or MK4. To conclude, in this study, neither high-dose phylloquinone nor MK4 reduced the ovx-associated increase in bone turnover or decline in DFBMD.     

Pathological fracture does not affect prognosis in dedifferentiated chondrosarcoma of the limbs

BackgroundThe aim of this retrospective study is to analyze history and treatment outcomes of pathological fracture (PF) in dedifferentiated chondrosarcoma (DdChS) of the limbs..MethodsWe retrospectively reviewed 175 adult patients with primary DdChS of the limbs.Disease-specific survival (OS) and local recurrence (LR) were analyzed.ResultsMedian age was 66 years (range, 29–91). Most DdChS (121, 69.1%) were localized in the femur. Forty-nine (28.0%) had metastasis at diagnosis; thirty-nine DdChS (22.3%) had a PF.OS rate was lower in patients with metastasis at diagnosis (8.6% Vs 41.0% at 10 years, p < 0.001). A similar OS was observed among patients with localized disease, whether with/without PF (p = 0.638), with/without chemotherapy (p = 0.543) and independently from the type of surgery (resection/amputation) (p = 0.877).Amputation reduces the risk of LR (80.0% vs 63.1% at 5 years, p = 0.039), particularly in the PF group..ConclusionPatients with metastases have a particularly poor prognosis in DdChS, but pathological fracture does not influence prognosis in terms of survival and local control. Initial curative resection is essential in order to reduce the chance of recurrences. Amputation might be an option in patients with localized disease and a PF to reduce the risk of LR..     

Ondansetron does not affect alfentanil-induced ventilatory depression or sedation.

Ondansetron is a selective 5-hydroxytryptamine type 3 receptor antagonist effective as an antiemetic in patients experiencing post-operative or cancer chemotherapy-induced nausea and vomiting. Currently, no information is available regarding the interaction of ondansetron with opioids, although a serotonin antagonist might be expected to modify some opioid actions. This study was designed to measure the effects of ondansetron on alfentanil-induced ventilatory depression and sedation in healthy male volunteers. Ventilatory drive (measured as the end-tidal CO2 necessary to produce a minute ventilation of 15 l/min) was determined in 29 subjects using a modification of the Read rebreathing technique. Sedation was measured by asking the subjects to complete visual analog scales. Alfentanil was administered as a bolus (5 micrograms/kg) followed by a continuous infusion (0.25-0.75 micrograms.kg-1.min-1) for at least 90 min. Study medication (ondansetron 8 or 16 mg or vehicle placebo) was then administered in a randomized, double-blind manner, and the alfentanil was infused for an additional 15 min. Measurements of ventilatory drive and sedation were made at baseline, during alfentanil infusion, after study medication, and at 30-min intervals after alfentanil was discontinued. Alfentanil produced significant ventilatory depression (P less than 0.001) and sedation (P less than 0.001) in all three groups. Neither placebo nor ondansetron produced further change in the intensity of either alfentanil effect. After discontinuation of the opioid, both ventilatory depression and sedation decreased, and the rate of recovery was not significantly different between groups. The data indicate that alfentanil-induced sedation and ventilatory depression are not significantly affected by the subsequent administration of ondansetron.     

Cigarette smoking does not affect thiopentone pharmacodynamic or pharmacokinetic behaviour

Purpose

Smoking affects the pharmacodynamic and pharmacokinetic behaviour of several drugs. In smokers, induction of anaesthesia is often stormy. In this study we have determined whether cigarette smoking affected thiopentone pharmacodynamic or pharmacokinetic behaviour during induction of anaesthesia.

Methods

Fifteen smokers and 15 non-smokers, scheduled for elective surgery, were studied. Heart rate, invasive arterial pressures and middle latency auditory evoked potentials were recorded awake and during thiopentone induction (9 mg·kg^?1 lean body mass), before and after tracheal intubation. Blood was sampled up to 24 hr after induction to measure thiopentone plasma concentrations and to calculate pharmacokinetic parameters.

Results

Anaesthesia was adequate in all patients, although haemodynamic intubation response was not blunted. Latencies or amplitudes of middle latency auditory evoked potentials (MLAEP) did not differ between the groups. The postintubation latencies of Nb waves were 48.9 ± 8.1 msec (mean ± SD) in smokers and 48.1 ± 8.5 msec in nonsmokers. Pharmacokinetic data showed no differences between smokers and non-smokers. Clearance of thiopentone was 2.9 ± 1.1 ml·min^?1 ·kg^?1 in smokers and 3.3 ± 1.0 ml·min^?1 ·kg^?1 in non-smokers and elimination half life of thiopentone was 12.5 ± 6.3 hr in smokers and 10.7 ± 3.1 hr in non-smokers, respectively. The haemodynamic response after the induction dose of thiopentone and after tracheal intubation were similar in smokers and non-smokers. Mean postintubation systolic arterial pressures were 192 ± 35 vs 189 ± 20 mmHg and mean postintubation heart rates were 103 ± 12 vs 102 ± 17 beat per minute (bpm) in smokers and non-smokers, respectively.

Conclusion

We conclude, that cigarette smoking does not affect the pharmacodynamic or pharmacokinetic behaviour of thiopentone.     

Low dose of propranolol does not affect rat osteotomy healing and callus strength

Experimental studies suggest that the β‐blocker propranolol stimulates bone formation but little work has investigated its effect on fracture healing. In this study, we examined if a low dose of propranolol, previously shown to be preventive against bone loss in rats, improves bone repair. Female Wistar rats were injected with saline or propranolol (0.1 mg/kg/day) (n = 20/group), 5 days a week for 8 weeks. Three weeks after the beginning of treatment, all rats underwent a mid‐diaphyseal transverse osteotomy in the left femur. Radiographic analysis of ostetomy healing was performed 2 and 5 weeks after osteotomy. Rats were sacrificed at 5 weeks and femora collected for measurements of fracture strength by torsional testing, callus volume, and mineral content by micro‐CT analysis and histology of fracture callus. Eighty nine percent of osteotomies achieved apparent radiological union by 5 weeks in both groups. Propranolol treatment did not significantly alter the torsional strength of the fractured femur compared with controls. The volume and mineralization of fracture callus at 5 weeks were not significantly different in both groups. Histology showed that endochondral ossification was not affected by propranolol. Altogether, our results demonstrate that propranolol using the regimen described does not significantly improve or inhibit rat osteotomy healing and mechanical strength. © 2014 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. J Orthop Res 32:887–893, 2014.