Progression Of Heterotopic Ossification Research Articles

Matrine reduces traumatic heterotopic ossification in mice by inhibiting M2 macrophage polarization through the MAPK pathway

In this study, the role of matrine, a component derived from traditional Chinese medicine, in modulating macrophage polarization and its effects on traumatic heterotopic ossification (HO) in mice was investigated. Traumatic HO is a pathological condition characterized by abnormal bone formation in nonskeletal tissues, often following severe trauma or surgery. The mechanisms underlying HO involve an enhanced inflammatory response and abnormal bone formation, with macrophages playing a crucial role. Our study demonstrated that matrine effectively inhibits the polarization of bone marrow-derived macrophages (BMDMs) toward the M2 phenotype, a subtype associated with anti-inflammatory processes and implicated in the progression of HO. Using in vitro assays, we showed that matrine suppresses key M2 markers and inhibits the MAPK signaling pathway in BMDMs. Furthermore, in vivo experiments revealed that matrine treatment significantly reduced HO formation in the Achilles tendons of mice and downregulated the expression of markers associated with M2 macrophages and the MAPK pathway. Our findings suggest that the ability of matrine to modulate macrophage polarization and inhibit the MAPK pathway has therapeutic potential for treating traumatic HO, providing a novel approach to managing this complex condition.

Malvidin attenuates trauma-induced heterotopic ossification of tendon in rats by targeting Rheb for degradation via the ubiquitin-proteasome pathway.

The pathogenesis of trauma-induced heterotopic ossification (HO) in the tendon remains unclear, posing a challenging hurdle in treatment. Recognizing inflammation as the root cause of HO, anti-inflammatory agents hold promise for its management. Malvidin (MA), possessing anti-inflammatory properties, emerges as a potential agent to impede HO progression. This study aimed to investigate the effect of MA in treating trauma-induced HO and unravel its underlying mechanisms. Herein, the effectiveness of MA in preventing HO formation was assessed through local injection in a rat model. The potential mechanism underlying MA's treatment was investigated in the tendon-resident progenitor cells of tendon-derived stem cells (TDSCs), exploring its pathway in HO formation. The findings demonstrated that MA effectively hindered the osteogenic differentiation of TDSCs by inhibiting the mTORC1 signalling pathway, consequently impeding the progression of trauma-induced HO of Achilles tendon in rats. Specifically, MA facilitated the degradation of Rheb through the K48-linked ubiquitination-proteasome pathway by modulating USP4 and intercepted the interaction between Rheb and the mTORC1 complex, thus inhibiting the mTORC1 signalling pathway. Hence, MA presents itself as a promising candidate for treating trauma-induced HO in the Achilles tendon, acting by targeting Rheb for degradation through the ubiquitin-proteasome pathway.

Suppression of Overactive Insulin-Like Growth Factor 1 Attenuates Trauma-Induced Heterotopic Ossification in Mice

Heterotopic ossification (HO) is the ectopic bone formation in soft tissues. Aside from hereditary HO, traumatic HO is common after orthopedic surgery, combat-related injuries, severe burns, or neurologic injuries. Recently, mTOR has been demonstrated to be involved in the chondrogenic and osteogenic processes of HO formation. However, its upstream signaling mechanism remains unknown. In this study, using an Achilles tendon puncture-induced HO model, we revealed that overactive insulin-like growth factor 1 (IGF-1) was involved in the progression of HO in mice. Micro-CT imaging showed that IGF-1 not only accelerated the rate of osteogenesis and increased ectopic bone volume but also induced spontaneous ectopic bone formation in undamaged Achilles tendons. Blocking IGF-1 activity with IGF-1 antibody or IGF-1 receptor (IGF-1R) inhibitor Picropodophyllin significantly inhibited HO formation. Mechanistically, IGF-1/IGF-1R activates PI3K/Akt signaling to promote the phosphorylation of mTOR, resulting in the chondrogenic and osteogenic differentiation of tendon-derived stem cells (TDSCs) into chondrocytes and osteoblasts in vitro and in vivo. Inhibitors of PI3K (LY294002) and mTOR (Rapamycin) both suppressed the IGF-1-stimulated mTOR signal and mitigated the formation of ectopic bones significantly. In conclusion, our results indicated that IGF-1 mediated the progression of traumatic HO through PI3K/Akt/mTOR signaling, and suppressing IGF-1 signaling cascades attenuated HO formation, providing a promising therapeutic strategy targeting HO.

Coding and noncoding RNA profile of human heterotopic ossifications - Risk factors and biomarkers.

Heterotopic ossification (HO) means the formation of bone in muscles and soft tissues, such as ligaments or tendons. HO could have a genetic history or develop after a traumatic event, as a result of muscle injury, fractures, burns, surgery, or neurological disorders. Many lines of evidence suggest that the formation of HO is related to the pathological differentiation of stem or progenitor cells present within soft tissues or mobilized from the bone marrow. The cells responsible for the initiation and progression of HO are generally called HO precursor cells. The exact mechanisms behind the development of HO are not fully understood. However, several factors have been identified as potential contributors. For example, local tissue injury and inflammation disturb soft tissue homeostasis. Inflammatory cells release growth factors and cytokines that promote osteogenic or chondrogenic differentiation of HO precursor cells. The bone morphogenetic protein (BMP) is one of the main factors involved in the development of HO. In this study, next-generation sequencing (NGS) and RT-qPCR were performed to analyze the differences in mRNA, miRNA, and lncRNA expression profiles between muscles, control bone samples, and HO samples coming from patients who underwent total hip replacement (THR). As a result, crucial changes in the level of gene expression between HO and healthy tissues were identified. The bioinformatic analysis allowed to describe the processes most severely impacted, as well as genes which level differed the most significantly between HO and control samples. Our analysis showed that the level of transcripts involved in leukocyte migration, differentiation, and activation, as well as markers of chronic inflammatory diseases, that is, miR-148, increased in HO, as compared to muscle. Furthermore, the levels of miR-195 and miR-143, which are involved in angiogenesis, were up-regulated in HO, as compared to bone. Thus, we suggested that inflammation and angiogenesis play an important role in HO formation. Importantly, we noticed that HO is characterized by a higher level of TLR3 expression, compared to muscle and bone. Thus, we suggest that infection may also be a risk factor in HO development. Furthermore, an increased level of transcripts coding proteins involved in osteogenesis and signaling pathways, such as ALPL, SP7, BGLAP, BMP8A, BMP8B, SMPD3 was noticed in HO, as compared to muscles. Interestingly, miR-99b, miR-146, miR-204, and LINC00320 were up-regulated in HO, comparing to muscles and bone. Therefore, we suggested that these molecules could be important biomarkers of HO formation and a potential target for therapies.

Recommendations for the healthcare of patients with FOP

Fibrodysplasia ossificans progressiva (FOP) is avery rare, severe genetic disorder triggered by again-of-function mutation in the ACVR1 gene that codes for the typeI bone morphogenetic protein (BMP) receptor ACVR1 (activinAreceptor-type1), also known as ALK2 (activin receptor-like kinase-2). It leads to the onset and progression of heterotopic ossification (HO) in soft and connective tissue. HO is often preceded by episodes of soft tissue swelling or flare-ups. Flare-ups, characteristic of FOP, may be induced by trauma, infection, vaccination, or other medications, as well as surgical procedures or may occur spontaneously. As patients age, they develop severe mobility limitations due to progressive HO formation, including immobility, causing ashortened life expectancy. FOP's first characteristic clinical sign is the congenital malformation of one or both big toes with valgus axis deviation, which is present in almost all patients. To confirm the diagnosis, molecular genetic analysis of the ACVR1 gene is possible. This white paper aims to provide an overview of the necessary prerequisites and conditions for the care of patients with FOP and positively contribute to patients with FOP by improving the overall availability of knowledge. To achieve this, relevant aspects of the care of the very rare disease FOP are presented, from the initial diagnosis to the care in regular care based on the authors' knowledge (German FOP network) and the international FOP Treatment Guidelines. The recommendations presented here are addressed to all actors and decision-makers in the health care system and are also intended to inform patients and the public.

Spatiotemporal and microstructural characterization of heterotopic ossification in healing rat Achilles tendons.

Achilles tendon rupture is a common debilitating medical condition. The healing process is slow and can be affected by heterotopic ossification (HO), which occurs when pathologic bone-like tissue is deposited instead of the soft collagenous tendon tissue. Little is known about the temporal and spatial progression of HO during Achilles tendon healing. In this study we characterize HO deposition, microstructure, and location at different stages of healing in a rat model. We use phase contrast-enhanced synchrotron microtomography, a state-of-the-art technique that allows 3D imaging at high-resolution of soft biological tissues without invasive or time-consuming sample preparation. The results increase our understanding of HO deposition, from the early inflammatory phase of tendon healing, by showing that the deposition is initiated as early as one week after injury in the distal stump and mostly growing on preinjury HO deposits. Later, more deposits form first in the stumps and then all over the tendon callus, merging into large, calcified structures, which occupy up to 10% of the tendon volume. The HOs were characterized by a looser connective trabecular-like structure and a proteoglycan-rich matrix containing chondrocyte-like cells with lacunae. The study shows the potential of 3D imaging at high-resolution by phase-contrast tomography to better understand ossification in healing tendons.

The development of a mouse model to investigate the formation of heterotopic ossification.

Muscle injury and concomitant bone injury are important drivers to induce heterotopic ossification (HO). However, the related roles of muscle and concomitant bone injury in HO formation are still unclear. This study aims to develop a mouse model through the combination of hindlimb amputation (Am) and cardiotoxin (CTX) injection to investigate the mechanism of HO formation. The mice were randomly divided into Am group (Am of right hindlimb, n = 12), CTX group (CTX injection in the calf muscle of left hindlimb, n = 12) and Am + CTX group (the combination of Am of right hindlimb and CTX injection of left hindlimb, n = 18). MicroCT was used to evaluate the incidence of HO. Histology was used to investigate the progression of HO. The MicroCT showed that only Am or CTX injection failed to induce HO while the combination of Am and CTX injection successfully induced HO. The incidence of HO was significant in Am + CTX group on day 7 (0% vs 0% vs 83.3%, p = 0.001) and day 14 (0% vs 0% vs 83.3%, p = 0.048). HO was located on the left hindlimb where CTX was injected. Moreover, the bone volume and bone density on day 14 were higher than those on day 7 in Am + CTX group. Histology revealed the evidence of calcification and expression of osteogenic markers in calcification sites in Am + CTX group. In summary, the combination of Am and CTX injection could successfully induce dystrophic calcification/HO, which occurs in the location of muscle injury.

MTORC1 coordinates NF-κB signaling pathway to promote chondrogenic differentiation of tendon cells in heterotopic ossification.

Heterotopic ossification (HO) is a pathological bone formation based on endochondral ossification distinguished by ossification within muscles, tendons, or other soft tissues. There has been growing studies focusing on the treatment with rapamycin to inhibit HO, but the mechanism of mTORC1 on HO remains unclear. Tendon cells (TDs) are the first cells to form during tendon heterotopic ossification. Here, we used an in vivo model of HO and an in vitro model of chondrogenesis induction to elucidate the effect and underlying mechanism of mTORC1 in HO. The current study highlights the effect of rapamycin on murine Achilles tenotomy-induced HO and the role of mTORC1 signaling pathway on TDs. Our result showed that mTORC1 was activation in the early stage of HO, whereas the mTORC1 maintained low expression in the mature ectopic cartilage tissue and the ectopic bone formation sites. The use of mTORC1-specific inhibitor (rapamycin) immediately after Achilles tendon injury could suppress the formation of HO; once ectopic cartilage and bone had formed, treatment with rapamycin could not significantly inhibit the progression of HO. Mechanistically, mTORC1 stimulation by silencing of TSC1 promoted the expression of the chondrogenic markers in TDs. In TDs, treated with mTORC1 stimulation by silencing of TSC1, mTORC1 increased the activation of the NF-κB signaling pathway. NF-κB selective inhibitor BAY11-7082 significantly suppressed the chondrogenesis of TDs that treated with mTORC1 stimulation by silencing of TSC1. Together, our findings demonstrated that mTORC1 promoted HO by regulating TDs chondrogenesis partly through the NF-κB signaling pathway; and rapamycin could be a viable HO therapeutic regimen.

Gnas Loss Causes Chondrocyte Fate Conversion in Cranial Suture Formation

Calvaria development is distinct from limb formation. Craniosynostosis is a skull deformity characterized by premature cranial suture fusion due to the loss of the GNAS gene and, consequently, its encoded protein Gαs. This birth defect requires surgery, with potential lethal consequences. So far, hardly any early-stage nonsurgical interventions for GNAS loss-related craniosynostosis are available. Here, we investigated the role of the Gnas gene in mice in guarding the distinctiveness of intramembranous ossification and how loss of Gnas triggered endochondral-like ossification within the cranial sutures. Single-cell RNA sequencing (scRNA-seq) of normal neonatal mice cranial suture chondrocytes showed a Hedgehog (Hh) inactivation pattern, which was associated with Gαs signaling activation. Loss of Gnas evoked chondrocyte-to-osteoblast fate conversion and resulted in cartilage heterotopic ossification (HO) within cranial sutures and fontanels of the mouse model, leading to a skull deformity resembling craniosynostosis in patients with loss of GNAS. Activation of ectopic Hh signaling within cranial chondrocytes stimulated the conversion of cell identity through a hypertrophy-like stage, which shared features of endochondral ossification in vivo. Reduction of Gli transcription activity by crossing with a loss-of-function Gli2 allele or injecting GLI1/2 antagonist hindered the progression of cartilage HO in neonatal stage mice. Our study uncovered the role of Gαs in maintaining cranial chondrocyte identity during neonatal calvaria development in mice and how reduction of Hh signaling could be a nonsurgical intervention to reduce skull deformity in craniosynostosis due to loss of GNAS.

Three-Dimensional Modeling of the Structural Microenvironment in Post-Traumatic War Wounds

BACKGROUND:The development of post-traumatic heterotopic ossification (HO) is a common, undesirable sequela in patients with high-energy (war-related) extremity injuries. While inflammatory and osteoinductive signaling pathways are known to be involved in the development and progression of post-traumatic HO, features of the structural microenvironment within which the ectopic bone begins to form remain poorly understood. Thus, increasing our knowledge of molecular and structural changes within the healing wound may help elucidate the pathogenesis of post-traumatic HO and aid in the development of specific treatment and/or prevention strategies.METHODS:In this study, we performed high-resolution microscopy and biochemical analysis of tissues obtained from traumatic war wounds to characterize changes in the structural microenvironment. In addition, using an electrospinning approach, we modeled this microenvironment to reconstitute a three-dimensional type I collagen scaffold with non-woven, randomly oriented nanofibers where we evaluated the performance of primary mesenchymal progenitor cells.RESULTS:We found that traumatic war wounds are characterized by a disorganized, densely fibrotic collagen I matrix that influences progenitor cells adhesion, proliferation and osteogenic differentiation potential.CONCLUSION:Altogether, these results suggest that the structural microenvironment present in traumatic war wounds has the potential to contribute to the development of post-traumatic HO. Our findings may support novel treatment strategies directed towards modifying the structural microenvironment after traumatic injury.

Enhance the study on surgical indication for cervical artificial disc replacement and reduce the occurrence of heterotopic ossification

Heterotopic ossification(HO) and progressive bone formation(PBF) are main factors affecting the motion ability of target segments after cervical artificial disc replacement(CADR).The severity of pre-operative degeneration of target segment is the most important factor in the occurrence and progression of HO and PBF. The occurrence and progression of HO and PBF can be reduced basically through the improvement of degeneration evaluation system for intervertebral disc (including height, range of motion and osteophyte formation), uncovertebral joint and facet joint and standardization of surgical indication. The application of new anatomical prosthesis and improved surgical technique are also important factors to reduce the occurrence and development of HO and PBF.

Small molecule inhibition of non-canonical (TAK1-mediated) BMP signaling results in reduced chondrogenic ossification and heterotopic ossification in a rat model of blast-associated combat-related lower limb trauma.

Heterotopic ossification (HO) is defined as ectopic bone formation around joints and in soft tissues following trauma, particularly blast-related extremity injuries, thermal injuries, central nerve injuries, or orthopaedic surgeries, leading to increased pain and diminished quality of life. Current treatment options include pharmacotherapy with non-steroidal anti-inflammatory drugs, radiotherapy, and surgical excision, but these treatments have limited efficacy and have associated complication profiles. In contrast, small molecule inhibitors have been shown to have higher specificity and less systemic cytotoxicity. Previous studies have shown that bone morphogenetic protein (BMP) signaling and downstream non-canonical (SMAD-independent) BMP signaling mediated induction of TGF-β activated kinase-1 (TAK1) contributes to HO. In the current study, small molecule inhibition of TAK1, NG-25, was evaluated for its efficacy in limiting ectopic bone formation following a rat blast-associated lower limb trauma and a murine burn tenotomy injury model. A significant decrease in total HO volume in the rat blast injury model was observed by microCT imaging with no systemic complications following NG-25 therapy. Furthermore, tissue-resident mesenchymal progenitor cells (MPCs) harvested from rats treated with NG-25 demonstrated decreased proliferation, limited osteogenic differentiation capacity, and reduced gene expression of Tac1, Col10a1, Ibsp, Smad3, and Sox2 (P<0.05). Single cell RNA-sequencing of murine cells harvested from the injury site in a burn tenotomy injury model showed increased expression of these genes in MPCs during stages of chondrogenic differentiation. Additional in vitro cell cultures of murine tissue-resident MPCs and osteochondrogenic progenitors (OCPs) treated with NG-25 demonstrated reduced chondrogenic differentiation by 10.2-fold (P<0.001) and 133.3-fold (P<0.001), respectively, as well as associated reduction in chondrogenic gene expression. Induction of HO in Tak1 knockout mice demonstrated a 7.1-fold (P<0.001) and 2.7-fold reduction (P<0.001) in chondrogenic differentiation of murine MPCs and OCPs, respectively, with reduced chondrogenic gene expression. Together, our in vivo models and in vitro cell culture studies demonstrate the importance of TAK1 signaling in chondrogenic differentiation and HO formation and suggest that small molecule inhibition of TAK1 is a promising therapy to limit the formation and progression of HO.

Diagnostic Value of Magnetic Resonance Imaging in Fibrodysplasia Ossificans Progressiva.

ABSTRACTUsing [18F] Sodium Fuoride (NaF) Positron Emission Tomography (PET) it is not only possible to identify the ossifying potency of a flare‐up, but also to identify an asymptomatic chronic stage of fibrodysplasia ossificans progressiva (FOP). The purpose of this study was to investigate the diagnostic role of a more widely available imaging modality, Magnetic Resonance Imaging (MRI), which is of special interest for studies in pediatric FOP patients. MRI and [18F]NaF PET/CT images at time of inclusion and subsequent follow‐up CT scans of 4 patients were analyzed retrospectively. Presence, location, and intensity of edema identified by MRI were compared with activity on [18F]NaF PET. Occurrence or progression of heterotopic ossification (HO) was examined on the follow‐up CT images. Thirteen different lesions in various muscle groups were identified: five lesions with only edema, five lesions with both edema and increased [18F]NaF uptake, one lesion with only increased [18F]NaF uptake, and two lesions with neither edema nor uptake of [18F]NaF. Mild edema, found in three lesions, was present at asymptomatic sites, which did not show increased [18F] NaF uptake or progression of HO on consecutive CT images. Moderate edema was found in three symptomatic lesions, with increased [18F]NaF on PET and progression of HO on CT. Severe edema was identified in four lesions. Interestingly, two of these lesions did not develop HO during follow‐up; one of these two even gave obvious symptoms of a flare‐up. MRI can identify whether symptoms are the result of an acute flare‐up by the presence of moderate to severe edema. The occurrence of severe edema on MRI was not always related to an ossifying lesion. The additional diagnostic value of MRI requires further investigation, but MRI does not seem to fully replace the diagnostic characteristics of [18F]NaF PET/CT in FOP. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Color Doppler ultrasound visualizes early post-traumatic heterotopic ossification in animal model

Objective To validate the role of color Doppler ultrasound in an animal model to detect early heterotopic ossification (HO) after brain-traumatic/burn/tenotomy. Methods Forty-four rats were randomly divided into two groups. Rats in experimental group (n=22) were operated to build brain-traumatic/burn/tenotomy model and others in control group (n=22) underwent only skin incision injury. Color Doppler ultrasound, X-ray film examination at 2, 3, 4, 6, 8 and 10 weeks post-injury were performed to follow up the progression of HO in both groups respectively. Histology was used to confirm bone formation. Results In the experimental group, disorder structure with a hypoechoiccore in treated Achilles tendon was visualized using color Doppler ultrasound in the 2nd week. Additional tiny hyperechoic foci were observed in the 3rd week, which increased in the fourth week and fused into a mineralized island in the sixth week. No obvious abnormality was found in control group at the aforementioned time point. X-ray could detect heterotopic bone tissue in the sixth week in the experimental group but not in the control group. X-ray and HE stainning had confirmed bone formation in the tenth week in the experimental group. Conclusions Color Doppler ultrasound can detect early HO and continuously follow up the progression of HO. Key words: Ultrasonography; Heterotopic ossification; Animal model; X-ray

Fibrodysplasia ossificans progressiva: Review and research activities in Japan.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic skeletal disorder manifesting progressive heterotopic ossification (HO) and congenital malformation of the great toes. Since 2007, we have conducted research on FOP. Here, we review the findings on FOP published to date, including the results of our research. Epidemiological studies in Japan have indicated that FOP has nearly the same prevalence in Japan as in the rest of the world. Basic research on its pathoetiology has progressed rapidly since the identification of the causal gene in 2006. Clinical and radiological findings have been thoroughly researched, including early radiological signs, and diagnostic criteria were established, designating FOP as an intractable disease in Japan. In patients with FOP, the progression of HO is associated with numerous disabilities, often manifesting in vicious cycles that can lead to early mortality. Through cross-sectional and short-term longitudinal studies, we have explored patient education, quality of life, and activities of daily living among Japanese patients. The management of FOP requires education of patients and caregivers, the use of medications to settle inflammation and flare-ups, instructions to ensure proper oral care, and other compensatory approaches that aid in rehabilitation. An avoidance of medical intervention, which may cause HO to progress, is also important. The advent of new drugs to prevent HO could have clinical benefit.

Heterotopic Ossification in Orthopaedic and Trauma surgery: A Histopathological Ossification Score

Heterotopic Ossification (HO) is a potential long-term complication in orthopaedic surgery. It is commonly classified according to the Brooker classification, which is based on radiological findings. To our knowledge the correlation of histological features to the Brooker grade is unknown as is the association between HO and the indication for revision. The aim of this paper is to analyze the ossification grade of HO tissue in patients undergoing revision hip and knee arthroplasty and to propose a histologically based classification system for HO. We also assess the relationship between the grade of HO and the indication for revision (septic and aseptic revision). From January to May 2019 we collected 50 human HO samples from hip and knee revision arthroplasty cases. These tissue samples were double-blinded and sent for histopathological diagnostic. Based on these results, we developed a classification system for the progression of HO. The grade of ossification was based on three characteristics: Grade of heterotopic ossification (Grade 1–3), presence of necrosis (N0 or N1) and the presence of osteomyelitis (HOES-Score Type 1 to 5). Demographic data as well as surgical details and indication for surgery was prospectively collected from clinical records. Fifty tissue samples were harvested from 44 hips and 6 knee joints. Of these 33 exhibited Grade I ossifications (66%), followed by 11 Grade II (22%) and one Grade III (2%). Necrosis was noted in two tissue samples (4%) and 2 more had osteomyelitis findings according to HOES-Score. Six samples (12%) with radiologically suggestive of HO turned out to be wear-induced synovitis, SLIM Type 1. Of these cases 16 were septic (32%) and 34 aseptic (68%) revisions. Most of the HO tissue samples were classified as a low-grade. High-grade ossification-Score is rare. Higher grades of ossification seem to be associated with septic revision cases. Wear-induced synovitis potentially influences HO development. A histological scoring system for ossification grading can be derived from the data presented in this study.

Celecoxib cannot inhibit the progression of initiated traumatic heterotopic ossification

Heterotopic ossification (HO) is a recognized sequela after trauma and arthroplasty. The purpose of this study was to evaluate the therapeutic effect of celecoxib on HO. We hypothesized that celecoxib may inhibit the progression of initiated HO. We performed a retrospective review of 37 patients who underwent elbow joint surgery between January 2014 and June 2018. Seventeen patients were prescribed orally administered celecoxib (200 mg/dose, twice daily) for 2 months after the diagnosis of HO, whereas the remaining 20 patients were administered celecoxib for 1 month starting immediately after surgery. HO progression was evaluated by plain radiographs. By use of an Achilles tendon puncture-induced HO mouse model, the curative effect of celecoxib was illustrated at different HO progression stages. The mice were assigned to 1 of 4 groups: sham group, vehicle group, group receiving celecoxib on day 1, and group receiving celecoxib in week 6. Achilles tendons were analyzed by micro-computed tomography and histochemistry after 12 weeks. Celecoxib did not inhibit the progression of initiated HO in the patients in whom HO was diagnosed, whereas those who received celecoxib after surgery had lower morbidity. Achilles tendon puncture effectively induced typical HO in mice. The ectopic bone volume was significantly reduced in the day 1 celecoxib group compared with the vehicle group; however, the difference was not statistically significant in the week 6 celecoxib group. Administration of celecoxib starting immediately after surgery can significantly inhibit the formation of HO. Once HO is visible on plain radiographs or micro-computed tomography, celecoxib cannot effectively attenuate further progression of HO in humans and mice.

Tamoxifen Inhibits the Progression of Trauma-Induced Heterotopic Ossification in Mice.

BackgroundHeterotopic ossification (HO) is a kind of abnormal mineralized bone which usually occurs in muscle, tendon, or ligament. There are currently no effective drugs for the treatment and prevention of HO. Developing effective drugs that can inhibit HO is of profound significance and would provide new strategies for clinical treatment of this disease. The present investigation evaluated the inhibitory effect of tamoxifen against HO.Material/MethodsUsing an Achilles tendon trauma-induced HO female mice model, we screened different doses of tamoxifen (1, 3, and 9 mg/kg) in mice to determine the optimal dosage on the inhibition of the HO formation. The curative effect of tamoxifen was also illustrated at different HO progression stages including inflammation, chondrogenesis, osteogenesis, and HO maturation.ResultsHeterotopic bone was formed with typical endochondral ossification in Achilles tendons 6 weeks after surgery and continued to enlarge up to 12 weeks. The formation of HO was significantly inhibited with the treatment of tamoxifen at the dosage of 9 mg/kg, whereas 1 mg/kg and 3 mg/kg did not reduce HO bone volume remarkably. The progression of HO was both attenuated by tamoxifen from Day 1 and Week 4 post-surgery, whereas no inhibitory effect was shown at the osteogenesis and maturation stages treated with tamoxifen.ConclusionsTamoxifen exerts an inhibitory effect on the heterotopic bone progression at inflammation and chondrogenesis stages, with the TGF-β signaling pathway suppressed following the increase in estrogen receptor α activity.

119. Ten-year outcomes of one- and two-level cervical disc arthroplasty: results from a US multicenter study

BACKGROUND CONTEXT Short- and mid-term studies have shown the effectiveness of cervical disc arthroplasty (CDA) to treat cervical disc degeneration. Upon completion of the 7-year Mobi-C FDA study, follow-up continued on a subset of CDA patients in the FDA study. PURPOSE The purpose of this study is to report the 10-year outcomes of a multicenter experience with cervical arthroplasty for 1- and 2-level pathology. STUDY DESIGN/SETTING This was a prospective cohort study of patients treated with cervical disc replacement at one or two contiguous levels using the Mobi-C® Cervical Disc. PATIENT SAMPLE Following completion of the 7-year FDA post approval study, follow-up continued to 10 years for consenting patients at 9 high-enrolling centers. The primary inclusion criteria were cervical degenerative disc at one or two contiguous levels and no prior cervical operations. OUTCOME MEASURES Outcome measures included NDI, VAS neck and arm pain, patient satisfaction, secondary surgical procedures (removals, revisions, reoperations, or additional fixation) and adverse events. Radiographic end points included segmental and global range of motion, sagittal alignment, adjacent level degeneration (ALD) and heterotopic ossification (HO). Radiographic ALD was defined with the Kellgren-Lawrence scale. HO was classified by the system adapted from McAfee and Mehren. Independent radiologists (Medical Metrics, Inc., Houston, TX) conducted radiographic evaluations. METHODS From the original enrollment of 257 CDA patients at 9 sites, 231 patients were eligible for follow-up after 7 years. Ten-year follow-up was obtained from 187 patients (81% follow-up). The longest follow-up was 11.2 years. Radiographs were obtained from 170 patients at 10 years. There were no significant differences in preoperative characteristics between these patients and the original FDA cohort. RESULTS Ten years after CDA, patients continued to show significant improvement from baseline NDI, VAS neck and arm pain, and neurologic function. Outcomes at 10 years were improved from results at 7 years for NDI at one (14.2 vs 18.7; p=0.12) and two levels (15.6 vs 19.7; p=0.02). Comparable results were observed for neck and arm pain. These improvements were less than the MCID for NDI and pain. There were no significant differences in outcomes between 1- and 2-level CDA at 10 years. Segmental flexion-extension range of motion remained significantly higher (p 0.05). The incidence of clinically relevant HO at 10 years was not significantly different from the 7-year incidence for 1-level (30.7% vs 29.6%; p=0.88) or 2-level (41.7% vs 39.2%; p=0.70) CDA patients. Only 2 subsequent surgeries were reported after 7 years. One patient underwent supplemental fixation at the index level 9.5 years after CDA. The other case was ACDF at a nonadjacent level unrelated to the CDA. Total incidence of subsequent surgery after 10 years was 4.7% (12/257) at the index level and 3.5% (9/257) at an adjacent level. CONCLUSIONS At 10-years, both 1- and 2-level CDA demonstrate sustained improvement of NDI, pain scores, range of motion and sagittal alignment compared to baseline. Progression of ALD and HO from 7 to 10 years was minimal. Our results through 10 years demonstrate that CDA with Mobi-C continues to be a safe and effective surgical treatment for patients with 1- or 2-level cervical degenerative disc disease. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.

Does Heterotopic Ossification in Cervical Arthroplasty Affect Clinical Outcome?

To investigate the occurrence and progression of heterotopic ossification (HO) in patients treated by anterior cervical discectomy with arthroplasty. It was evaluated if HO affects clinical outcome and range of motion (ROM). Risk factors of HO was studied as well. Patients who underwent anterior cervical discectomy with arthroplasty for a cervical radiculopathy because of a herniated disc from the NECK and PROCON trial were analyzed for HO at 12 and 24 months postoperatively. HO was scored according to the McAfee-Mehren classification. The index ROM was defined by a custom developed image analysis tool, and global cervical ROM was measured by Cobb's angle. Clinical outcome was evaluated by means of the Neck Disability Index and the 36-Item Short Form Health Survey. The occurrence of HO was 60% at 1 year, and it increased to 76% at 2-year follow-up. A total of 31% of patients were scored as high-grade HO at 1-year follow-up, and this percentage increased to 50% at 2-year follow-up. Clinical outcome does not correlate to HO grade, and no risk factor for high-grade HO could be identified. The ROM at the index level was significantly higher in low-grade HOgroup than those patients with high-grade HO, but in 15%-38% HO grade does not correspond to ROM. HO occurs in three fourths of the patients at 2 years after surgery, but does not necessarily correspond to clinical outcome, nor loss or preservation of ROM. The McAfee-Mehren classification should be combined with ROM evaluation to properly study HO.