Heterotopic Ossification and Hypertrophic Scars

Younger age correlates with increased gutter impingement rates after total ankle arthroplasty

BACKGROUND

While total ankle arthroplasty (TAA) has evolved over the years with improved designs and enhanced bony fixation methods, it remains a technically demanding procedure with a risk of early postoperative complications. One of the most common complications associated with TAA is medial and lateral gutter ankle impingement, which can lead to issues such as increased pain and decreased range of motion (ROM). However, there is a paucity of information in the literature discussing the impact of certain risk factors on gutter impingement complications.

METHODS

A retrospective analysis was conducted on a cohort of patients who underwent a TAA at a single institution from 2003 to 2019 with a minimum of 2-year follow-up. Patient were identified as having gutter impingement based on diagnostic imaging and/or clinical examination. Data collection included demographics, implant type, follow-up time, and co-morbidities. Multivariate odds ratios (OR) of experiencing gutter impingement were calculated for perioperative variables.

RESULTS

The study included a total of 908 patients who underwent TAA with a minimum of 2 year follow up and 121 patients (13.3 %) who subsequently experienced gutter impingement. The average follow-up time was 5.84 + /- 3.07 years. There were 178 patients under 55 years old, 495 patients aged 55 to 70, and 235 patients over 70 years old. A higher rate of gutter impingement was observed in patients under 55 years of age compared to those aged 55 to 70 and over 70 (20.8 % vs. 13.5 % vs. 7.2 %; p < 0.01). Multivariable logistic regression revealed that patient age was significantly correlated with gutter impingement following TAA, with an OR of 0.94 (CI: 0.91-0.98; p < 0.01).

CONCLUSION

This study demonstrated increased incidence of gutter impingement in younger patients who underwent TAA. Propensity for scar tissue formation may be higher in this population. Scar tissue deposition following TAA can cause narrowing of the medial and lateral clear spaces, potentially leading to gutter impingement. Additionally, younger patients may have increased activity demands, which subsequently may cause higher rates of symptomatic impingement. As increased impingement after TAA may require the need for additional debridement surgeries, it is important to understand the intricate relationship between age and gutter impingement for managing patient expectations following TAA.

LEVEL OF EVIDENCE

Level III.

Patients with hypertrophic scars following severe burn injury express different long noncoding RNAs

OBJECTIVE

Research indicates that long noncoding RNAs (lncRNAs) contribute significantly to fibrotic diseases. Although lncRNAs may play a role in hypertrophic scars after burns, its mechanisms remain poorly understood.

METHODS

Using chip technology, we compared the lncRNA expression profiles of burn patients and healthy controls (HCs). Microarray results were examined by quantitative reverse-transcription polymerase chain reaction (RT-PCR) to verify their reliability. The biological functions of differentially expressed mRNAs and the relationships between genes and signaling pathways were investigated by Gene Ontology (GO) and pathway analyses, respectively.

RESULTS

In contrast with HCs, it was found that 2738 lncRNAs (1628 upregulated) and 2166 mRNAs (1395 upregulated) were differentially expressed in hypertrophic scars after burn. Results from RT-PCR were consistent with those from microarray. GO and pathway analyses revealed that the differentially expressed mRNAs are mainly associated with processes related to cytokine secretion in the immune system, notch signaling, and MAPK signaling.

CONCLUSION

The lncRNA expression profiles of hypertrophic scars after burn changed significantly compared with HCs. It was believed that the transcripts could be used as potential targets for inhibiting abnormal scar formation in burn patients.

Physical and psychosocial outcomes among burn-injured people with heterotopic ossification: A burn model system study

INTRODUCTION

Heterotopic ossification (HO), or ectopic bone formation in soft tissue, is a not so rare and poorly understood debilitating sequela of burn injury. Individuals developing HO following burn injuries to their hands often experience reductions in mobility, significant contractures, and joint pain. This study identifies demographic characteristics of individuals who develop HO and compares their physical and psychosocial outcomes to the general burn population.

METHODS

Participant demographics, injury characteristics, and PROMIS-29 scores across three time points (discharge, six- and 12- months after injury) were extracted from the Burn Model System National Longitudinal Database representing participants from 2015-2022. Mixed-effects linear regression models were used to compare PROMIS scores across all three longitudinal measurements. Models were adjusted for age, sex, race/ethnicity, HO status, and burn size.

RESULTS

Of the 861 participants with data concerning HO, 33 were diagnosed with HO (3.8% of participants). Most participants with HO were male (n = 24, 73%) and had an average age of 40 + /- 13 years. Participants with HO had significantly larger burn size (49 +/-23% Total Body Surface Area (TBSA)) than those without HO (16 +/-17%). Participants with HO reported significantly worse physical function, depression, pain interference and social integration scores than those without HO. After adjusting for covariables, participants with HO continued to report statistically significantly worse physical function than those without HO. Although physical functioning was consistently lower, the two populations did not differ significantly among psychosocial outcome measures.

CONCLUSIONS

While HO can result in physical limitations, the translation to psychosocial impairments was not evident. Targeted treatment of HO with the goal of maximizing physical function should be a focus of their rehabilitation.

LEVEL OF EVIDENCE

2b TYPE OF STUDY: Symptom Prevalence Study.

Calcified apoptotic vesicles from PROCR+ fibroblasts initiate heterotopic ossification

Heterotopic ossification (HO) comprises the abnormal formation of ectopic bone in extraskeletal soft tissue. The factors that initiate HO remain elusive. Herein, we found that calcified apoptotic vesicles (apoVs) led to increased calcification and stiffness of tendon extracellular matrix (ECM), which initiated M2 macrophage polarization and HO progression. Specifically, single-cell transcriptome analyses of different stages of HO revealed that calcified apoVs were primarily secreted by a PROCR+ fibroblast population. In addition, calcified apoVs enriched calcium by annexin channels, absorbed to collagen I via electrostatic interaction, and aggregated to produce calcifying nodules in the ECM, leading to tendon calcification and stiffening. More importantly, apoV-releasing inhibition or macrophage deletion both successfully reversed HO development. Thus, we are the first to identify calcified apoVs from PROCR+ fibroblasts as the initiating factor of HO, and might serve as the therapeutic target for inhibiting pathological calcification.

Drugs targeting TGF-β/Notch interaction attenuate hypertrophic scar formation by optic atrophy 1-mediated mitochondrial fusion

Hypertrophic scar (HS) formation is a cutaneous fibroproliferative disease that occurs after skin injuries and results in severe functional and esthetic disability. To date, few drugs have shown satisfactory outcomes for the treatment of HS formation. Transforming growth factor-beta (TGF-β)/Notch interaction via small mothers against decapentaplegic 3 (Smad3) could facilitate HS formation; therefore, targeting TGF-β/ Notch interaction via Smad3 is a potential therapeutic strategy to attenuate HS formation. In addition, optic atrophy 1 (OPA1)-mediated mitochondrial fusion contributes to fibroblast proliferation, and TGF-β/Smad3 axis and the Notch1 pathway facilitate OPA1-mediated mitochondrial fusion. Thus, the aim of this study was to investigate whether drugs targeting TGF-β/Notch interaction via Smad3 suppressed fibroblast proliferation to attenuate HS formation through OPA1-mediated mitochondrial fusion. We found that the TGF-β pathway, Notch pathway, and TGF-β/Notch interaction via Smad3 were inhibited by pirfenidone, the gamma- secretase inhibitor DAPT, and SIS3 in human keloid fibroblasts (HKF) and an HS rat model, respectively. Protein interaction was detected by co-immunoprecipitation, and mitochondrial morphology was determined by electron microscopy. Our results indicated that pirfenidone, DAPT, and SIS3 suppressed the proliferation of HKFs and attenuated HS formation in the HS rat model by inhibiting TGF-β/Notch interaction via Smad3. Moreover, pirfenidone, DAPT, and SIS3 hindered OPA1-mediated mitochondrial fusion through inhibiting TGF-β/Notch interaction, thereby suppressing the proliferation of HS fibroblasts and HS formation. In summary, these findings investigating the effects of drugs targeting TGF-β/Notch interaction on HS formation might lead to novel drugs for the treatment of HS formation.

Enhanced BMP signaling in Cathepsin K-positive tendon progenitors induces heterotopic ossification

Heterotopic ossification (HO) is abnormal bone growth in soft tissues that results from injury, trauma, and rare genetic disorders. Bone morphogenetic proteins (BMPs) are critical osteogenic regulators which are involved in HO. However, it remains unclear how BMP signaling interacts with other extracellular stimuli to form HO. To address this question, using the Cre-loxP recombination system in mice, we conditionally expressed the constitutively activated BMP type I receptor ALK2 with a Q207D mutation (Ca-ALK2) in Cathepsin K-Cre labeled tendon progenitors (hereafter "Ca-Alk2:Ctsk-Cre"). Ca-Alk2:Ctsk-Cre mice were viable but they formed spontaneous HO in the Achilles tendon. Histological and molecular marker analysis revealed that HO is formed via endochondral ossification. Ectopic chondrogenesis coincided with enhanced GLI1 production, suggesting that elevated Hedgehog (Hh) signaling is involved in the pathogenesis of HO. Interestingly, focal adhesion kinase, a critical mediator for the mechanotransduction pathway, was also activated in Ca-Alk2:Ctsk-Cre mice. Our findings suggest that enhanced BMP signaling may elevate Hh and mechanotransduction pathways, thereby causing HO in the regions of the Achilles tendon.

Burn Injury Cutaneous Functional Units: Allocating Occupational Therapy Resources and Influencing Practice

Burn injury severity is currently determined by estimating the total body surface area (TBSA) burned, but this method fails to capture the severity of subsequent functional consequences. Alternatively, cutaneous functional units (CFUs)--skin segments that accommodate for movement and commonly become contracted--can be used to more accurately estimate burn severity based on functional consequences. Bilateral hands account for 81.3% of the body's CFUs, though only account for 5% of TBSA. However, hand burn survivors can have worse physical outcomes (ie, contractures, deformities) after burn injury, leading to subsequent loss of function, global occupational participation deficits, and poor psychosocial outcomes. This study, conducted at a verified American Burn Association burn center, explores how CFU involvement among adult burn survivors with uni and bilateral hand and upper extremity burns influenced occupational therapy practice in regards to time spent completing scar and soft tissue elongation techniques from the elbow to the digit tips per patient. The data showed, on average, burn occupational therapists require 0.8 minutes per CFU for an average total of 38.7 (SD = 29.5) minutes each session to complete scar and soft tissue elongation techniques to the upper extremities. The results of this study can be used to educate burn centers on the clinical utility of CFUs, burn occupational therapists regarding best-practice in terms of utilization of therapist time and resources, as well as support the justification for increasing occupational therapy services for patients with upper extremity and hand burns, and increasing staffing to meet patient need.

Salvianolic Acid B Attenuates Hypertrophic Scar Formation In Vivo and In Vitro

BACKGROUND

Hypertrophic scars (HTSs) are a fibroproliferative disorder that occur following skin injuries. Salvianolic acid B (Sal-B) is an extractant from Salvia miltiorrhiza that has been reported to ameliorate fibrosis in multiple organs. However, the antifibrotic effect on HTSs remains unclear. This study aimed to determine the antifibrotic effect of Sal-B in vitro and in vivo.

METHODS

In vitro, hypertrophic scar-derived fibroblasts (HSFs) were isolated from human HTSs and cultured. HSFs were treated with (0, 10, 50, 100 μmol/L) Sal-B. Cell proliferation and migration were evaluated by EdU, wound healing, and transwell assays. The protein and mRNA levels of TGFβI, Smad2, Smad3, α-SMA, COL1, and COL3 were detected by Western blots and real-time PCR. In vivo, tension stretching devices were fixed on incisions for HTS formation. The induced scars were treated with 100 μL of Sal-B/PBS per day according to the concentration of the group and followed up for 7 or 14 days. The scar condition, collagen deposition, and α-SMA expression were analyzed by gross visual examination, H&E, Masson, picrosirius red staining, and immunofluorescence.

RESULTS

In vitro, Sal-B inhibited HSF proliferation, migration, and downregulated the expression of TGFβI, Smad2, Smad3, α-SMA, COL1, and COL3 in HSFs. In vivo, 50 and 100 μmol/L Sal-B significantly reduced scar size in gross and cross-sectional observations, with decreased α-SMA expression and collagen deposition in the tension-induced HTS model.

CONCLUSIONS

Our study demonstrated that Sal-B inhibits HSFs proliferation, migration, fibrotic marker expression and attenuates HTS formation in a tension-induced HTS model in vivo.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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

BACKGROUND

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.

METHOD

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.

RESULTS

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.

CONCLUSION

In summary, the combination of Am and CTX injection could successfully induce dystrophic calcification/HO, which occurs in the location of muscle injury.

Biophysical and in vitro wound healing assessment of collagen peptides processed from fish skin waste

The present study was conducted to examine the bioactive and wound healing properties of collagen hydrolysate derived from Piaractus brachypomus (pacu) fish skin waste. Collagen type I (P coll.) yielding 72.25% was isolated from skin waste by following acid-soluble collagen extraction method. Further, collagen was fragmented using bacterial collagenase and the processed collagen hydrolysate (peptides) was in the range of 10–15 kDa that was further purified using ion-exchange chromatography. The FTIR spectra of both P coll. and collagen hydrolysate (PSCH) were nearly similar showing that PSCH retained the structural and chemical composition similar to its parent molecule (P coll.). Solubility analysis revealed that PSCH has slightly better solubility compared to P coll. Similarly, scanning electron micrographs also exhibited more uniform and porous microstructure of PSCH compared to P coll. Further, PSCH was found to be efficient in peroxide quenching (64.5%) and radical scavenging activities (85.74%). MTT studies confirmed PSCH to be non-toxic displaying 84.68% cell viability at the highest concentration (3 mg/ml) and hemocompatibility test revealed PSCH to be non-hemolytic with minimal lysis of only 2.1% of human RBCs. In addition, PSCH also displayed a remarkable wound closure ability of more than 80% at 12 h and 100% within 24 h. Hence, these findings suggest that recycled PSCH has potent wound healing ability and can be produced economically on a large scale for possible biological applications in regenerative medicine.

Spätmanifeste Kalzinose in Brandnarben: Eine Literaturübersicht und zwei Fallberichte

Calcinosis cutis, die heterotope Ablagerung von Kalziumsalzen in der Haut, wurde in einigen Fällen als spät auftretende Komplikation von Brandnarben beschrieben. Sie unterscheidet sich diesbezüglich von heterotoper Ossifikation, die eine früh einsetzende Komplikation von Brandverletzungen sein kann. Die Diagnose einer Kalzinose kann radiographisch, sonographisch, computertomographisch, magnetresonanztomographisch oder histologisch bestätigt werden. Nahezu alle Fälle einer spätmanifesten Kalzinose bei Brandnarben imponieren als nicht heilendes Ulkus an den unteren Extremitäten in der Nähe der Kontrakturbänder. Es wird diskutiert, dass diese Lokalisation auf die häufigeren Mikrotraumen an den unteren Extremitäten zurückzuführen ist, und dass die Ulzeration aufgrund der Kalziumablagerungen als Fremdkörper auftritt. In unserer Studie betrug das Durchschnittsalter zum Zeitpunkt der Brandverletzung 12,5 ± 8,27 Jahre und die Kalzinose entwickelte sich im Mittel nach einer Zeitspanne von 37,5 ± 14,95 Jahren (das Durchschnittsalter bei Beginn war 50,5 ± 14,53 Jahre). Es gab keinen signifikanten Unterschied zwischen Brandnarben, die mittels Hauttransplantation behandelt wurden, und solchen, bei denen keine Hauttransplantation durchgeführt wurde. Die Ulzera verheilten nach Resektion oder Extraktion der Ablagerungen ohne Rezidiv an derselben Stelle. Im Gegensatz zu früher gemeldeten Fällen beobachteten wir zwei Fälle einer spät einsetzenden Kalzinose ohne Ulzeration bei Brandnarben an den oberen Extremitäten.

Late-onset calcinosis in burn scars: A review of the literature and two case reports

Calcinosis cutis is a heterotopic accumulation of calcium salts in the skin. It has been described as a late‐onset complication of burn scars in a few cases, in contrast to heterotopic ossification, which may be an early‐onset complication of burn injuries. Diagnosis of calcinosis can be confirmed by radiography, ultrasonography, computed tomography, magnetic resonance imaging or histology. Almost all cases of late‐onset calcinosis in burn scars present as non‐healing ulcers on the lower extremities near contracture bands. It has been hypothesized that this localization is due to the more frequent microtrauma of the lower extremities, and that ulceration is due to the presence of calcium deposits as foreign bodies. In our study, the mean age at the time of burn injury was 12.5 ± 8.27 years, and calcinosis developed after a mean time of 37.5 ± 14.95 years (mean age at onset was 50.5 ± 14.53 years). There was no significant difference between burn scars managed with skin grafting and those where skin grafting was not carried out. The ulcers healed after resection or extraction of the deposits without any recurrence at the same site. In contrast to previously reported cases, we observed two cases of non‐ulcerating late‐onset calcinosis in burn scars of the upper extremities.

Changes of Migration, Immunoregulation and Osteogenic Differentiation of Mesenchymal Stem Cells in Different Stages of Inflammation

Bone infection has always been the focus of orthopedic research. Mesenchymal stem cells (MSCs) are the natural progenitors of osteoblasts, and the process of osteogenesis is triggered in response to different signals from the extracellular matrix. MSCs exert important functions including secretion and immune regulation and also play a key role in bone regeneration. The biological behavior of MSCs in acute and chronic inflammation, especially the transformation between acute inflammation and chronic inflammation, has aroused great interest among researchers. This paper reviews the recent literature and summarizes the behavior and biological characteristics of MSCs in acute and chronic inflammation to stimulate further research on MSCs and treatment of bone diseases.

Tenomodulin knockout mice exhibit worse late healing outcomes with augmented trauma-induced heterotopic ossification of Achilles tendon

Heterotopic ossification (HO) represents a common problem after tendon injury with no effective treatment yet being developed. Tenomodulin (Tnmd), the best-known mature marker for tendon lineage cells, has important effects in tendon tissue aging and function. We have reported that loss of Tnmd leads to inferior early tendon repair characterized by fibrovascular scaring and therefore hypothesized that its lack will persistently cause deficient repair during later stages. Tnmd knockout (Tnmd-/-) and wild-type (WT) animals were subjected to complete Achilles tendon surgical transection followed by end-to-end suture. Lineage tracing revealed a reduction in tendon-lineage cells marked by ScleraxisGFP, but an increase in alpha smooth muscle actin myofibroblasts in Tnmd-/- tendon scars. At the proliferative stage, more pro-inflammatory M1 macrophages and larger collagen II cartilaginous template were detected in this group. At the remodeling stage, histological scoring revealed lower repair quality in the injured Tnmd-/- tendons, which was coupled with higher HO quantified by micro-CT. Tendon biomechanical properties were compromised in both groups upon injury, however we identified an abnormal stiffening of non-injured Tnmd-/- tendons, which possessed higher static and dynamic E-moduli. Pathologically thicker and abnormally shaped collagen fibrils were observed by TEM in Tnmd-/- tendons and this, together with augmented HO, resulted in diminished running capacity of Tnmd-/- mice. These novel findings demonstrate that Tnmd plays a protecting role against trauma-induced endochondral HO and can inspire the generation of novel therapeutics to accelerate repair.

Radiation Oncology Applications in Plastic and Reconstructive Surgery: A Nonsystematic Review of Concepts and Principles

SUMMARY

Careful consideration of radiotherapy can determine the success of reconstructive therapy. There is a broad spectrum of radiotherapy modalities, both benign and malignant. Delivery mechanisms differ in the physical design, setup, radiation source, administrable dosage, and mode of delivery. This range of options allows radiation oncologists to tailor individualized treatment; however, radiotherapy concepts can be challenging for nonspecialists. The purpose of this article is to review general radiation oncology concepts, including essential equipment and radiobiology, and provide plastic surgeons with a basic conceptual understanding to facilitate effective multidisciplinary collaboration with radiation oncologists.

A review of animal models from 2015 to 2020 for preclinical chronic wounds relevant to human health

SIGNIFICANCE

Chronic wounds fail to heal in a timely manner and exhibit sustained inflammation with slow tissue repair and remodelling. They decrease mobility and quality of life, and remain a major clinical challenge in the long-term care of many patients, affecting 6.5 million individuals annually in the U.S., decreasing mobility and quality of life. Treatment costs are a major burden on the U.S. healthcare system, totalling between $25 and $100 billion annually. Chronic wound severity depends upon several factors such as comorbidities, severity of tissue damage, infection and presence of necrosis and vary greatly in their healing mechanisms. In vivo animal models are critical for studying healing pathways of chronic wounds and seek to replicate clinical factors for trials of topical, systemic, and device-based therapeutics. This comprehensive review discusses murine, rat, lapine, canine, feline and porcine models of chronic wounds.

RECENT ADVANCES

Foundational chronic wound models for several species are discussed together with refinements and advances in the time period between 2015 and 2020 which have the potential for broad utility in investigating biological and device-based wound treatment therapies for human health.

CRITICAL ISSUES

Chronic wounds fail to heal in a timely manner and have differing aetiologies, rendering no single in vivo animal model universally applicable.

FUTURE DIRECTIONS

Further studies are required to develop clinically relevant chronic wound animal model which reflect the clinical reality of the various influences of age, disease, comorbidities and gender on delayed healing and enhance understanding of the biological processes of human wound healing.

Mechanical stretch promotes hypertrophic scar formation through mechanically activated cation channel Piezo1

Hypertrophic scar (HS) formation is a skin fibroproliferative disease that occurs following a cutaneous injury, leading to functional and cosmetic impairment. To date, few therapeutic treatments exhibit satisfactory outcomes. The mechanical force has been shown to be a key regulator of HS formation, but the underlying mechanism is not completely understood. The Piezo1 channel has been identified as a novel mechanically activated cation channel (MAC) and is reportedly capable of regulating force-mediated cellular biological behaviors. However, the mechanotransduction role of Piezo1 in HS formation has not been investigated. In this work, we found that Piezo1 was overexpressed in myofibroblasts of human and rat HS tissues. In vitro, cyclic mechanical stretch (CMS) increased Piezo1 expression and Piezo1-mediated calcium influx in human dermal fibroblasts (HDFs). In addition, Piezo1 activity promoted HDFs proliferation, motility, and differentiation in response to CMS. More importantly, intradermal injection of GsMTx4, a Piezo1-blocking peptide, protected rats from stretch-induced HS formation. Together, Piezo1 was shown to participate in HS formation and could be a novel target for the development of promising therapies for HS formation.

A rare case of a cystic renal mass with heterotopic ossification and a mini literature review

INTRODUCTION

It is a challenge to make accurate pre-surgical diagnosis for renal tumors. This study is to report the findings, management, and outcome of one rare case of ossification in a cystic renal mass. We present and discuss the pathological characteristics, radiologic features, and treatment alternatives of the patient.

PATIENTS AND METHODS

A 38 years old female patient had intermittent epigastric pain and microscopic hematuria for two months. Computerized tomography (CT) scan and Magnetic Resonance imaging (MRI) showed a mass with rough edge and dense calcification in the upper pole of the right kidney and normal left kidney. Pre-operative diagnosis is cystic nephroma or cystic renal mass (Bosniak III type, Bosniak renal cyst classification). GFR was within normal limits for age and no other significant laboratory aberrations were noted. Patient underwent a right retroperitoneal laparoscopic partial nephrectomy (margin status was negative). A mini literature review was performed to highlight the principals of diagnosis and treatment of cystic renal mass with heterotopic ossification.

RESULTS

The entire renal mass was successfully removed from upper pole of the right kidney by laparoscopic nephron sparing surgery. The size of renal mass is 38×35×30 mm3 with thick and hard capsular wall. The cystic cavity contains yellow lipid-like substances without stone. Histological examination revealed renal cyst in which the cyst wall reveals fibrosis and no obvious lining epithelium. The additional unique feature includes the presence of dense calcification and ossification in the renal mass. Localization tissue of yellow bone marrow was detected. No complications occurred in 9 months after surgery during follow-up.

CONCLUSIONS

Cystic renal mass with heterotopic ossification is a rare case of non-malignant renal tumor. Whether surgery is needed depends to whether patients have symptoms. For symptom renal tumors, laparoscopic nephron sparing surgical procedure is recommended. Furthermore, complete surgical resection of the lesion is needed when the mass is suspected to be malignant. An accurate histologic diagnosis is key in its diagnosis.

Heterotopic ossification after local steroid injection

Pachydermodactyly (PDD) is a rare, benign disease associated with progressive swelling of the periarticular soft tissue of phalangeal hand joints typically treated with local steroid injections. We present a case of a 37-year-old man with PDD treated with local steroid injections. He later developed heterotopic ossification and para-articular calcifications in the injection sites. Heterotopic ossification is not associated with PDD nor is it a recognised complication of local steroid injections. This is the first case in literature of heterotopic ossification occurring after local steroid injection and brings to attention a new potential complication of a widely performed procedure.

A Case Report of Heterotopic Ossification Caused by High-Voltage Electric Injury

This case report described the diagnosis and treatment of a patient with ectopic bone injury due to high-pressure electric shock. A 24-year-old male patient suffered from burns that covered 50% of TBSA, including on limbs and torso, after coming into contact with 10-kV high-voltage electricity. A repeated Meek micrografting technique (MEEK) was applied for wound healing; skin grafts were cut into micrografts and expanded at a ratio of 1:4 to cover large areas after burn trauma. After the injury, right elbow redness, fever, pains, and joint movement disorder were reported by the patient, which might be attributed to excessive exercises and acute scarring. However, these symptoms were not treated immediately. Six months after the injury, his right elbow joint showed 90° locking and a restricted 5° movement capacity. X-ray examination revealed a new bone formation at the inner tibia shin. In addition, 3D CT showed the formation of right tibia, the ruler bone, and the skull of the humming bridge. Under general anesthesia, the right elbow joint was released, the medial collateral ligament was repaired, and the hinge external fixator was fixed. A large number of hyperplastic bone masses were found at the right elbow joint during surgery, specifically in the foot bone hawk's beak nest. No complications after surgery were observed. X-ray examination in February showed disappearance of the bone bridge and normal relationship of the right elbow joint. This case study revealed that electric shock injury could lead to ectopic bone formation, and much attention should be paid on any changes that indicate aseptic inflammation, such as redness, swelling, fever, and pain during the treatment process. Finally, identification of the scar constriction phase could indicate surgical treatment in order to promote the limb rehabilitation process.

Bioinformatics Analysis of the Molecular Mechanism of Late-Stage Heterotopic Ossification

Background

Heterotopic ossification (HO) is a common disease happened in soft tissues after injury. The present study utilized the bioinformatics method to analyze the HO samples in a mouse burn/tenotomy-induced HO model to identify the possible key points and treatment targets.

Methods

The transcriptome profiles of GSE126118 were obtained from the Gene Expression Omnibus (GEO) database. The study was based on a mouse burn/tenotomy-induced HO model, and 2 tenotomy samples and 3 uninjured contralateral hindlimb tendon samples were collected at 3 weeks after injury for further analysis. The transcripts per million approach was performed for background correction and normalization; then, the differentially expressed genes (DEGs) were detected using the limma R package with the settings p < 0.01 and ∣log2FC∣ > 2.0. The Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and the protein-protein interaction (PPI) network analysis were performed with the detected DEGs.

Results

A total of 74 DEGs were upregulated, and 159 DEGs were downregulated between the tenotomy and uninjured tendon group. Pathway and process enrichment analyses demonstrated that the upregulated DEGs were mainly associated with terms related to ECM remodeling, ossification, angiogenesis, inflammation, etc., and the downregulated DEGs were mainly associated with oxidative phosphorylation, metabolic process, etc.

Conclusion

The results of GO, KEGG, and PPI network analyses suggested that the ECM remodeling, ossification, angiogenesis, and inflammation processes were markedly upregulated in the tenotomy site. And the oxidative phosphorylation and metabolic processes were markedly downregulated. These findings provide valuable clues for highlighting the characteristics of late-stage HO and investigating possible treatments.

Regulation of heterotopic ossification by monocytes in a mouse model of aberrant wound healing

Heterotopic ossification (HO) is an aberrant regenerative process with ectopic bone induction in response to musculoskeletal trauma, in which mesenchymal stem cells (MSC) differentiate into osteochondrogenic cells instead of myocytes or tenocytes. Despite frequent cases of hospitalized musculoskeletal trauma, the inflammatory responses and cell population dynamics that regulate subsequent wound healing and tissue regeneration are still unclear. Here we examine, using a mouse model of trauma-induced HO, the local microenvironment of the initial post-injury inflammatory response. Single cell transcriptome analyses identify distinct monocyte/macrophage populations at the injury site, with their dynamic changes over time elucidated using trajectory analyses. Mechanistically, transforming growth factor beta-1 (TGFβ1)-producing monocytes/macrophages are associated with HO and aberrant chondrogenic progenitor cell differentiation, while CD47-activating peptides that reduce systemic macrophage TGFβ levels and help ameliorate HO. Our data thus implicate CD47 activation as a therapeutic approach for modulating monocyte/macrophage phenotypes, MSC differentiation and HO formation during wound healing.

Osteoimmunology: A Current Update of the Interplay Between Bone and the Immune System

Immunology, already a discipline in its own right, has become a major part of many different medical fields. However, its relationship to orthopedics and trauma surgery has unfortunately, and perhaps unjustly, been developing rather slowly. Discoveries in recent years have emphasized the immense breadth of communication and connection between both systems and, importantly, the highly promising therapeutic opportunities. Recent discoveries of factors originally assigned to the immune system have now also been shown to have a significant impact on bone health and disease, which has greatly changed how we approach treatment of bone pathologies. In case of bone fracture, immune cells, especially macrophages, are present throughout the whole healing process, assure defense against pathogens and discharge a complex variety of effectors to regulate bone modeling. In rheumatoid arthritis and osteoporosis, the immune system contributes to the formation of the pathological and chronic conditions. Fascinatingly, prosthesis failure is not at all solely a mechanical problem of improper strain but works in conjunction with an active contribution of the immune system as a reaction to irritant debris from material wear. Unraveling conjoined mechanisms of the immune and osseous systems heralds therapeutic possibilities for ailments of both. Contemplation of the bone as merely an unchanging support pillar is outdated and obsolete. Instead it is mandatory that this highly diverse network be incorporated in our understanding of the immune system and hematopoiesis.

Coordinating Tissue Regeneration Through Transforming Growth Factor-β Activated Kinase 1 Inactivation and Reactivation

Aberrant wound healing presents as inappropriate or insufficient tissue formation. Using a model of musculoskeletal injury, we demonstrate that loss of transforming growth factor-β activated kinase 1 (TAK1) signaling reduces inappropriate tissue formation (heterotopic ossification) through reduced cellular differentiation. Upon identifying increased proliferation with loss of TAK1 signaling, we considered a regenerative approach to address insufficient tissue production through coordinated inactivation of TAK1 to promote cellular proliferation, followed by reactivation to elicit differentiation and extracellular matrix production. Although the current regenerative medicine paradigm is centered on the effects of drug treatment ("drug on"), the impact of drug withdrawal ("drug off") implicit in these regimens is unknown. Because current TAK1 inhibitors are unable to phenocopy genetic Tak1 loss, we introduce the dual-inducible COmbinational Sequential Inversion ENgineering (COSIEN) mouse model. The COSIEN mouse model, which allows us to study the response to targeted drug treatment ("drug on") and subsequent withdrawal ("drug off") through genetic modification, was used here to inactivate and reactivate Tak1 with the purpose of augmenting tissue regeneration in a calvarial defect model. Our study reveals the importance of both the "drug on" (Cre-mediated inactivation) and "drug off" (Flp-mediated reactivation) states during regenerative therapy using a mouse model with broad utility to study targeted therapies for disease. Stem Cells 2019;37:766-778.