Muscle contusion injury and myositis ossificans traumatica

Main anatomical characteristics of the hominin fossil humeri from the Sima de los Huesos Middle Pleistocene site, Sierra de Atapuerca, Burgos, Spain: An update

Some of the Sima de los Huesos (SH) humeri have been previously studied and described elsewhere. Here we present an updated inventory and a review of the specimens recovered to the present day. The morphological key traits of the adult and subadult specimens are described, discussed, and illustrated. The SH humeri share with Neandertals many traits usually considered to be Neandertal specializations, thus, most of this morphological pattern is not exclusive to them. The variation found within fossil samples stresses the frequential nature of all these traits and in the specific case of the SH humeri, most of the traits considered as phylogenetically relevant are retained by their descendants, the Neandertals. Some traits are plesiomorphic for the entire genus Homo or are present in European hominins since the early Pleistocene. Finally, some other traits display high variability within the SH sample or different hominin samples and are of uncertain phylogenetic value. Altogether, this evidence is consistent with the hypothesis based on the overall cranial and postcranial morphology that the SH hominins are a sister group to the later Neandertals.

Genetic regulation of injury-induced heterotopic ossification in adult zebrafish

Heterotopic ossification is the inappropriate formation of bone in soft tissues of the body. It can manifest spontaneously in rare genetic conditions or as a response to injury, known as acquired heterotopic ossification. There are several experimental models for studying acquired heterotopic ossification from different sources of damage. However, their tenuous mechanistic relevance to the human condition, invasive and laborious nature and/or lack of amenability to chemical and genetic screens, limit their utility. To address these limitations, we developed a simple zebrafish injury model that manifests heterotopic ossification with high penetrance in response to clinically emulating injuries, as observed in human myositis ossificans traumatica. Using this model, we defined the transcriptional response to trauma, identifying differentially regulated genes. Mutant analyses revealed that an increase in the activity of the potassium channel Kcnk5b potentiates injury response, whereas loss of function of the interleukin 11 receptor paralogue (Il11ra) resulted in a drastically reduced ossification response. Based on these findings, we postulate that enhanced ionic signalling, specifically through Kcnk5b, regulates the intensity of the skeletogenic injury response, which, in part, requires immune response regulated by Il11ra.

Evaluating postcranial macromorphoscopic traits to estimate population variation among modern South Africans

Population overlap and the variation within and among populations have been globally observed but is often difficult to quantify. To achieve this, numerous different methods need to be explored and validated to assist with the creation of an accurate biological profile. The current lack of databases for postcranial macromorphoscopic traits indicates the need to further investigate if the method can be employed repeatably in a forensic context. The current study aimed to assess the prevalence of eleven postcranial macromorphoscopic traits in a South African sample. A total of 271 postcrania of adult black, coloured, and white South Africans were assessed. The intra- and inter-observer agreement ranged from fair to almost perfect except for the accessory transverse foramen of C1, which had poor agreement between observers. Only seven traits differed significantly between at least two of the groups. Univariate and multivariate random forest models were created to test the positive predictive performance of the traits to classify population affinity. The classification accuracies for the univariate models ranged from 33.3% to 53.0% and ranged from 54.6% to 62.1% for the multivariate models. Based on the variable importance, the traits assessing spinous process bifurcation were the most discriminatory variables. The results indicate that the postcranial MMS approach does not outperform current methods employed to estimate population affinity. Further research needs to be done for the method to have practical applicability for medicolegal casework in South Africa.

Ossified intramuscular hematoma of the paraspinal muscles: a case report

Background

Ossified intramuscular hematomas (OIH) are an exceptionally rare condition that may be mistaken for alternative calcified intramuscular pathologies, such as myositis ossificans. Exceedingly few cases of OIHs have been reported to date, with no cases yet to be reported in the paraspinal muscles.

Case presentation

Here, we report on a patient who presented with a chronic back pain and swelling in the setting of trauma 15 years prior. Radiographic workup revealed a calcified mass in the erector spinae muscles. The lesion was surgically excised, and histologic examination confirmed the presence of an OIH. The patient did well postoperatively.

Conclusion

An OIH is a poorly understood pathology. Although benign, these lesions can cause significant morbidity, and surgical excision is a reasonable and safe treatment option. OIHs may be distinguished from related calcified intramuscular pathologies based on key clinical features and distinct histopathology. Clinically, they are characterized by a history of remote trauma and, on histopathology, by compact, mature bone in the setting of an old, organizing hematoma. Despite this, similarities with other calcified intramuscular pathologies persist, and further study is warranted to better understand and classify these lesions.

A rare femoral heterotopic bone formation in a 14th-19th century female skeleton from Constância (Portugal)

OBJECTIVE

This paper aims to: (1) document a rare femoral heterotopic ossification (HO), and (2) discuss its aetiology and impact on the individual's locomotion and daily living activities.

MATERIALS

Adult female skeleton (SG.14-SK.7) from the village of Constância (Portugal), and dated from the 14th-19th centuries CE.

METHODS

The biological profile and the macroscopic analysis of the bone changes were assessed using standardized methods.

RESULTS

The macroscopic analysis revealed a large bony mass (8 cm length) located immediately inferior to the small trochanter of the right femur. The lesion exhibited a compact, tubular appearance located at the site of attachment of the pectineus muscle. No signs of bone fracture were observed.

CONCLUSIONS

The morphology of the SG.14-SK.7 femoral lesion is compatible with a probable case of myositis ossificans traumatica (MOT), secondary to acute trauma of the pectineus muscle. The underlying trauma episode, such as random accidental and/or occupation-related injury, is unknown. However, it is highly possible that this self-limiting condition significantly impaired the individual's daily life and mobility.

SIGNIFICANCE

Evidence of severe acute muscle trauma is a rare finding compared with HO secondary to bone trauma and other minor muscle injuries. Moreover, no cases of MOT affecting the pectineus muscle have been reported in the paleopathological literature to date.

LIMITATIONS

Although unlikely, a case of neurogenic or burn-related HO cannot be completely disregarded. It was not possible to undertake radiography as part of this study.

SUGGESTIONS FOR FURTHER RESEARCH

The use of imaging techniques to complement the paleopathological description is advised.

Non‐traumatic myositis ossificans circumscripta in the anterior abdominal wall of a seven‐year‐old Ugandan child: A case report

Myositis ossificans circumscripta (MOC) is a benign and self‐limiting heterotopic ossification in the subcutaneous fat, tendons, muscles, and nerves. It is commonly due to trauma and is frequently encountered in the arm, shoulder, thigh, and hand which are prone to trauma. Non‐traumatic MOC arising from the abdominal muscles is extremely rare. We report a case of 7‐year‐old male child with a three‐year history of progressive painless abdominal swelling in the left hypochondria region with no history of associated trauma. CT scan of the abdomen showed a well‐defined hyperdense mass in the left external oblique muscle. Histological diagnosis confirmed myositis ossificans of the external oblique muscle. The mass was removed surgically with no immediate or late complications.

Non‐traumatic MOC of the abdominal muscles is very rare. Radiological investigations are crucial in the diagnosis and for differentiating a MO lesion from other malignant soft‐tissue tumors as we demonstrated in this case report.

Sustained local ionic homeostatic imbalance caused by calcification modulates inflammation to trigger heterotopic ossification

Heterotopic ossification (HO) is a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues. Despite being a frequent complication of orthopedic and trauma surgery, brain and spinal injury, the etiology of HO is poorly understood. The aim of this study is to evaluate the hypothesis that a sustained local ionic homeostatic imbalance (SLIHI) created by mineral formation during tissue calcification modulates inflammation to trigger HO. This evaluation also considers the role SLIHI could play for the design of cell-free, drug-free osteoinductive bone graft substitutes. The evaluation contains five main sections. The first section defines relevant concepts in the context of HO and provides a summary of proposed causes of HO. The second section starts with a detailed analysis of the occurrence and involvement of calcification in HO. It is followed by an explanation of the causes of calcification and its consequences. This allows to speculate on the potential chemical modulators of inflammation and triggers of HO. The end of this second section is devoted to in vitro mineralization tests used to predict the ectopic potential of materials. The third section reviews the biological cascade of events occurring during pathological and material-induced HO, and attempts to propose a quantitative timeline of HO formation. The fourth section looks at potential ways to control HO formation, either acting on SLIHI or on inflammation. Chemical, physical, and drug-based approaches are considered. Finally, the evaluation finishes with a critical assessment of the definition of osteoinduction. STATEMENT OF SIGNIFICANCE: The ability to regenerate bone in a spatially controlled and reproducible manner is an essential prerequisite for the treatment of large bone defects. As such, understanding the mechanism leading to heterotopic ossification (HO), a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues, would be very useful. Unfortunately, the mechanism(s) behind HO is(are) poorly understood. The present study reviews the literature on HO and based on it, proposes that HO can be caused by a combination of inflammation and calcification. This mechanism helps to better understand current strategies to prevent and treat HO. It also shows new opportunities to improve the treatment of bone defects in orthopedic and dental procedures.

Ultrasound Imaging in Sport-Related Muscle Injuries: Pitfalls and Opportunities

Muscle injuries occur frequently in athletes, accounting for more than one-third of sport-related trauma. Athletes most affected by these injuries are those practicing football and track and field, with hamstrings and gastrocnemius-soleus as the mainly involved sites. Muscle injuries lead to loss of competitions, long recovery times and risk of re-injury with a consequent increase of the management costs. It is therefore advisable to make an accurate and timely diagnosis to establish appropriate interventions for proper healing in the shortest time. In this context, ultrasound imaging is widely used for diagnosis of musculoskeletal disorders because of several advantages including absence of radiation, portability, good spatial resolution, and the ability to perform dynamic tests. The aim of this review is to address the role of US in the evaluation of athletes with muscle injuries. US may play a pivotal role for the management of sport-related muscle injuries because it is fast and relatively cheap, allowing dynamic muscle assessment and time series evaluation of the healing process.

Are open surgery and total resection good choices for traumatic myositis ossificans in children?

BACKGROUND

Traumatic myositis ossificans is a self-limited, non-neoplastic, ectopic bone formation in the soft tissues caused by trauma. Conservative treatment is the mainstay of management. However, open surgery and complete resection should be considered in patients with limited joint function and constant pain. Herein, we retrospectively analyzed the outcome of open surgical resection in children with myositis ossificans (MO).

METHODS

The data of patients diagnosed with MO between February 2010 and May 2019 were retrospectively analyzed. The clinical data included medical history, physical examination, and laboratory, imaging, and pathological findings. All patients underwent an open surgery and total resection. Radiography findings and joint function were evaluated. Patients with developing complications, such as recurrence and assessing joint function, were followed up. In total, 20 patients (sex, 15 male and 5 female patients; age, 8.1 ± 2.5 years) were included.

RESULTS

MO was located around the elbow, wrist, proximal humerus, and thigh in 13, one, one, and five patients, respectively. All patients were followed up for > 12 months. Two patients had partial recurrence after surgery. One patient with forearm MO had poor elbow function (Broberg-Morrey score of 70). Nineteen patients had good functional outcomes according to the Broberg-Morrey and Cooney methods.

CONCLUSION

Open surgical resection is an effective method for children with MO. The recurrence rate was low when the surgery was performed after the acute stage (1.5 months from disease presentation).

Post-traumatic myositis ossificans: a benign lesion that simulates malignant bone and soft tissue tumours

Myositis ossificans (MO) is a benign bone formation in an extra-skeletal location. The most common subtype of MO, the post-traumatic, usually develops in young males after a traumatic event or sports injury.MO may simulate malignant bone lesions such as extra-skeletal or surface osteosarcomas, or soft tissue sarcomas such as synovial sarcoma or undifferentiated pleomorphic sarcoma. In the early phase the diagnosis of MO is challenging because imaging and histopathological findings may be non-characteristic.Detailed medical history as well as clinical examination, follow-up imaging studies and histological assessment are crucial for a proper diagnosis. Early and accurate differential diagnosis between MO and malignant soft tissue and bone tumours is important to maximize. Cite this article: EFORT Open Rev 2021;6:572-583. DOI: 10.1302/2058-5241.6.210002.

Myositis ossificans revisited - The largest reported case series

INTRODUCTION

Myositis ossificans (MO) is a condition characterised by the formation of non-neoplastic heterotropic ossification in extraskeletal soft tissues.

MATERIAL AND METHODS

We performed a retrospective study of our radiology databases within our tertiary orthopaedic centre to identify all cases of MO, reported on X ray, Magnetic resonance imaging (MRI) and Computed tomography (CT) over the past 13 years (2007-2020).

RESULTS

We identified 68 cases of MO, which were included into our cohort. The average age of our patients was 36 years (range 4-84 years). 73% of cases (n = 50) were found to affect the lower limb muscles with the majority in the quadriceps.

CONCLUSION

We report the largest case series of MO and discuss the demographics, diagnoses and management.

Clinical Relevance and Immunohistochemical Patterns of Silent Pituitary Adenomas: 10 Years of Single-centre Experience

BACKGROUND

Silent pituitary adenomas are clinically non-functional (i.e., without clinically evident pituitary hormone production).

INTRODUCTION

The aim of this study was to investigate subjects with silent pituitary adenomas for possible variations in their clinical status.

METHODS

A total of 102 patients who had undergone surgery for pituitary adenoma and had been diagnosed with silent pituitary adenoma was included in the study. The patients' preoperative and postoperative hormonal parameters and magnetic resonance imaging (MRI) features were collected, and pathological specimens were re-evaluated.

RESULTS

Immunohistochemistry results of the 102 patients were as follows: hormone-negative adenomas (n=35) 35.5%; FSH+LH-positivity (n=32) 31.3%; ACTH-positivity (n=11) 10.7%; α-subunit- positivity (n= 9) 8.8%; prolactin-positivity (n=8) 7.8%; GH-positivity (n=6) 5.4%; and plurihormonal adenoma (n=1). The mean sizes of SGA, SGHA, and SCA were 28.0±12.7, 30.0±16.0, and 27.7±8.9mm (p>0.05), respectively. With the exception of silent gonadotroph adenomas (SGAs), female gender dominance was shown in patients with silent growth hormone adenoma (SGHA) and silent corticotroph adenoma (SCA). Although no clinical relevance was observed in relation to hormonal excess, preoperative GH (4.21±4.6, vs. 0.27±0.36 p=0.00) was slightly more elevated in SGHA than in GH-negative adenomas. Additionally, preoperative basal ACTH values (47.3±28.7 vs. 23.9±14.4, p=0.003) were also higher in SCA compared to the other types. Our findings revealed SCAs to be of more aggressive behaviour than SGHAs and SGAs due to invasiveness in radiological imaging, their elevated re-operation, and postoperative ACTH values.

CONCLUSION

Silent pituitary adenomas represent a challenging diagnostic tumour group. Careful initial evaluation of patients with pituitary adenomas should consider any mild signs and symptoms of functionality, particularly in cases of GH- and ACTH-secreting adenomas.

Cardiopulmonary and Neurologic Dysfunctions in Fibrodysplasia Ossificans Progressiva

Fibrodysplasia Ossificans Progressiva (FOP) is an ultra-rare but debilitating disorder characterized by spontaneous, progressive, and irreversible heterotopic ossifications (HO) at extraskeletal sites. FOP is caused by gain-of-function mutations in the Activin receptor Ia/Activin-like kinase 2 gene (Acvr1/Alk2), with increased receptor sensitivity to bone morphogenetic proteins (BMPs) and a neoceptor response to Activin A. There is extensive literature on the skeletal phenotypes in FOP, but a much more limited understanding of non-skeletal manifestations of this disease. Emerging evidence reveals important cardiopulmonary and neurologic dysfunctions in FOP including thoracic insufficiency syndrome, pulmonary hypertension, conduction abnormalities, neuropathic pain, and demyelination of the central nervous system (CNS). Here, we review the recent research and discuss unanswered questions regarding the cardiopulmonary and neurologic phenotypes in FOP.

Surgical excision of post-traumatic myositis ossificans of the adductor longus in a football player

A football player was diagnosed with myositis ossificans of his right adductor longus muscle after an acute injury. Conservative treatment failed and 1 year after the initial trauma the patient underwent surgical excision of a large ossification. Seven months postoperatively, the patient was fully recovered and returned to his preinjury activity levels. We present our approach to this case and discuss our considerations, referring to background information about this rare disease.

Muscle Injuries in Sports: A New Evidence-Informed and Expert Consensus-Based Classification with Clinical Application

Muscle injuries are among the most common injuries in sport and continue to be a major concern because of training and competition time loss, challenging decision making regarding treatment and return to sport, and a relatively high recurrence rate. An adequate classification of muscle injury is essential for a full understanding of the injury and to optimize its management and return-to-play process. The ongoing failure to establish a classification system with broad acceptance has resulted from factors such as limited clinical applicability, and the inclusion of subjective findings and ambiguous terminology. The purpose of this article was to describe a classification system for muscle injuries with easy clinical application, adequate grouping of injuries with similar functional impairment, and potential prognostic value. This evidence-informed and expert consensus-based classification system for muscle injuries is based on a four-letter initialism system: MLG-R, respectively referring to the mechanism of injury (M), location of injury (L), grading of severity (G), and number of muscle re-injuries (R). The goal of the classification is to enhance communication between healthcare and sports-related professionals and facilitate rehabilitation and return-to-play decision making.

MR Imaging of Muscle Trauma: Anatomy, Biomechanics, Pathophysiology, and Imaging Appearance

Muscle is an important component of the muscle-tendon-bone unit, driving skeletal motion through contractions that alter the length of the muscle. The muscle and myotendinous junction (MTJ) are most commonly injured in the young adult, as a result of indirect mechanisms such as overuse or stretching, direct impact (penetrating or nonpenetrating), or dysfunction of the supporting connective tissues. Magnetic resonance (MR) imaging is widely used for assessment of muscle injuries. This review illustrates the MR imaging appearance of a broad spectrum of acute, subacute, and chronic traumatic lesions of muscle, highlighting the pathophysiology, biomechanics, and anatomic considerations underlying these lesions. Concentric (shortening) contractions are more powerful, but it is eccentric (lengthening) contractions that produce the greatest muscle tension, leading to indirect injuries such as delayed-onset muscle soreness (DOMS) and muscle strain. Strain is the most commonly encountered muscle injury and is characteristically located at the MTJ, where maximal stress accumulates during eccentric exercise. The risk of strain varies among muscles based on their fiber composition, size, length, and architecture, with pennate muscles being at highest risk. Direct impact to muscle results in laceration or contusion, often accompanied by intramuscular interstitial hemorrhage and hematoma. Disorders related to the muscle's collagen framework include compartment syndrome, which is related to acute or episodic increases in pressure, and muscle herniation through anatomic defects in the overlying fascia. The healing response after muscle trauma can result in regeneration, degeneration with fibrosis and fatty replacement, or disordered tissue proliferation as seen in myositis ossificans. In athletes, accurate grading of the severity and precise location of injury is necessary to guide rehabilitation planning to prevent reinjury and ensure adequate healing. In elite athletes, MR imaging grading of muscle trauma plays an increasingly important role in recently developed comprehensive grading systems that are replacing the imprecise three-grade injury classification system currently used. ^©RSNA, 2017.

Imaging of Muscle Injuries in Sports Medicine: Sports Imaging Series

In sports-related muscle injuries, the main goal of the sports medicine physician is to return the athlete to competition-balanced against the need to prevent the injury from worsening or recurring. Prognosis based on the available clinical and imaging information is crucial. Imaging is crucial to confirm and assess the extent of sports-related muscle injuries and may help to guide management, which directly affects the prognosis. This is especially important when the diagnosis or grade of injury is unclear, when recovery is taking longer than expected, and when interventional or surgical management may be necessary. Several imaging techniques are widely available, with ultrasonography and magnetic resonance imaging currently the most frequently applied in sports medicine. This state of the art review will discuss the main imaging modalities for the assessment of sports-related muscle injuries, including advanced imaging techniques, with the focus on the clinical relevance of imaging features of muscle injuries. ^© RSNA, 2017 Online supplemental material is available for this article.

Decellularized extracellular matrix repair of volumetric muscle loss injury impairs adjacent bone healing in a rat model of complex musculoskeletal trauma

BACKGROUND

Traumatic muscle loss (i.e., volumetric muscle loss [VML] injury) impairs adjacent fracture healing but is often left untreated. A promising therapy for this application is a decellularized extracellular matrix (ECM) because of their capacity to regenerate a vascularized tissue bed. This study tested the hypothesis that repair of VML concomitant to fracture with a small intestine submucosa (SIS)-ECM improves musculoskeletal healing.

METHODS

In male Lewis rats (~375 g), a 3-mm segmental bone defect (SBD) was created in concomitance with a 6-mm, full-thickness VML injury to the adjacent tibialis anterior (TA) muscle. For all rats (n = 10), the SBD was treated with internal plate fixation and delivery of recombinant human bone morphogenetic protein 2 (1 μg) on a collagen sponge. The VML either had no repair or SIS-ECM repair (n = 5/group). Bone regeneration within the SBD (BV/TV [bone volume as a fraction of total volume]) was assessed via in vivo micro-computed tomography at 2, 4, and 6 weeks and histology at 6 weeks after injury. Tibialis anterior muscle in vivo strength and histologic assessments were performed at 6 weeks after injury.

RESULTS

Compared with no repair, SIS-ECM presented -21% (p = 0.09) and -27% (p = 0.004) BV/TV at 4 and 6 weeks after injury, respectively. At 6 weeks, the SBD gap length was shorter for the no repair than that for the SIS-ECM (2.64 ± 0.30 and 3.67 ± 0.41 mm, respectively; p = 0.09), whereas the distances from the end of each cortical segment to the center of the first stabilization screw were longer (1.86 ± 0.25 and 0.85 ± 0.30 mm, respectively; p = 0.035), indicating enhanced resorption in the SIS-ECM group. Both groups presented similar magnitude TA muscle strength deficits compared with their contralateral limbs (10-150 Hz: no repair, -58% to 67%; SIS-ECM, -51% to 74%). The TA muscle of the SIS-ECM group was remarkable for its presentation of fibrosis, edema, and immune cell presence.

CONCLUSIONS

Small intestine submucosa-ECM VML repair impaired open fracture healing and failed to improve skeletal muscle strength.

Myositis Ossificans of the Hip Due to Pyogenic Arthritis Caused by Campylobacter fetus Subspecies fetus

A 61-year-old woman was admitted with severe hip pain causing immobility and high serum levels of inflammatory markers. The patient had a medical history of diabetes. She had been scheduled to undergo right hip replacement surgery for the treatment of osteoarthritis associated with gradually progressive pain. On admission, an enhanced abdominal computed tomography scan showed an abnormal increase in synovial fluid surrounding the right ilium, with piriformis muscle calcification. Subsequent blood and specimen cultures identified Campylobacter fetus subspecies fetus. This is a rare report of a case of myositis ossificans followed by C. fetus pyogenic arthritis of the hip.

Hemophilia in Sports: A Case Report and Prophylactic Protocol

OBJECTIVE

 To describe a successful prophylactic protocol for managing an athlete with hemophilia playing at a high level of contact sports.

BACKGROUND

 Published data show that team physicians are not comfortable either treating athletes with bleeding disorders or allowing them to participate in contact sports. Much of the literature historically has recommended against allowing athletes with bleeding disorders to play sports at all and certainly against playing contact sports. Hemophilia treatment can now include prophylactic injections of recombinant factor VIII to prevent bleeding episodes. Modern treatments hold the promise of allowing athletes with hemophilia to participate in contact sports.

DIFFERENTIAL DIAGNOSIS

 Mild, moderate, or severe hemophilia; von Willebrand disease; other factor deficiencies.

TREATMENT

 A treatment protocol was developed that included prophylactic factor VIII injections on a regular basis and when the athlete was injured.

UNIQUENESS

 This is the first published case report of an athlete with known hemophilia being successfully treated and participating in National Collegiate Athletic Association collegiate basketball for 2 full seasons.

CONCLUSIONS

 Sports medicine teams can successfully manage an athlete with hemophilia playing a contact sport.

Myositis Ossificans Traumatica of the Thenar Region

Myositis ossificans of the hand is extremely rare. We report an unusual case of myositis ossificans of the thenar muscles and discuss the diagnostic pitfalls whereby this condition can be mistaken for malignancy or infection.

Myositis ossificans: A rare location in the foot. Report of a case and review of literature

BACKGROUND

Myositis ossificans is a benign, tumor-like lesion characterized by heterotopic ossification of soft tissue that usually affects the elbow and thigh. At different stages of maturity, it show similar histologic appearances with sarcomatous lesions or maturing bone. Misdiagnosis can result in unnecessary radical treatment.

CASE REPORT

A 50-year-old woman with dorsal forefoot soft tissue mass was diagnosed as myositis ossificans after surgical excision and confirmed by a histopathological examination.

DISCUSSION

To our knowledge, myositis ossificans occurrence in the foot is rare and only a few cases have been reported in the literature.

SUMMARY

Increasing awareness on the unusual sites for myositis ossificans occurrence is necessary for differentiating this lesion from a malignant soft- tissue tumors and avoiding diagnostic pitfalls and unnecessary investigations, which can have major consequences and complications for patients.

Muscle injuries and strategies for improving their repair

Satellite cells are tissue resident muscle stem cells required for postnatal skeletal muscle growth and repair through replacement of damaged myofibers. Muscle regeneration is coordinated through different mechanisms, which imply cell-cell and cell-matrix interactions as well as extracellular secreted factors. Cellular dynamics during muscle regeneration are highly complex. Immune, fibrotic, vascular and myogenic cells appear with distinct temporal and spatial kinetics after muscle injury. Three main phases have been identified in the process of muscle regeneration; a destruction phase with the initial inflammatory response, a regeneration phase with activation and proliferation of satellite cells and a remodeling phase with maturation of the regenerated myofibers. Whereas relatively minor muscle injuries, such as strains, heal spontaneously, severe muscle injuries form fibrotic tissue that impairs muscle function and lead to muscle contracture and chronic pain. Current therapeutic approaches have limited effectiveness and optimal strategies for such lesions are not known yet. Various strategies, including growth factors injections, transplantation of muscle stem cells in combination or not with biological scaffolds, anti-fibrotic therapies and mechanical stimulation, may become therapeutic alternatives to improve functional muscle recovery.

Myositis Ossificans of Rectus Femoris: A Rare Case Report

Introduction:

Myositis ossificans (MO), heterotopic ossification, occurs in muscles and soft tissue. This lesion contains actively proliferating fibroblasts and osteoblasts. It commonly affects vigorous young men and more so among athletes. It occurs as a result of trauma, either acute or chronic and can also arise near joints in neurological disorders. By time of presentation, ossification is extensive and the benign nature of the lesion is usually evident on radiological studies. Most common muscles involved in MO are the flexor muscles of the arm, the hamstrings and quadriceps femoris.

Case Report:

We present a case of MO with isolated involvement of rectus femoris in mid-thigh and sparing of other three muscles of quadriceps femoris, with no improvement following physiotherapy and medical management requiring surgical excision for better prognosis with no recurrence.

Conclusion:

MO, a benign lesion, is known to affect the flexors of the arm, the hamstrings, and quadriceps femoris; it must be noted that even individual muscle can also be affected as shown in the above case presentation without involving whole group of muscles. Surgical excision is indicated if non-operative measures are not successful.

Posttraumatic myositis ossificans of the hand : A locally aggressive malignancy-mimicking tumor

Posttraumatic myositis ossificans (PTMO) is the most common form of myositis ossificans, but it rarely affects the hand. Due to the aggressive behavior of this unusual tumor, it is commonly misdiagnosed as malignancy or local infection. This report describes a case of PTMO of the hand in a 25-year-old women, and reviews the clinical, radiologic, and histologic characteristics. By understanding the disease characteristics and maturation process, physicians can avoid a misdiagnosis that may lead to functional impairment or improper treatment.

Localized BIA identifies structural and pathophysiological changes in soft tissue after post-traumatic injuries in soccer players

Localized bioimpedance (BIA) was measured with a single frequency phase-sensitive analyzer at 50 kHz in three post-traumatic types of injuries on four professional soccer players: (1) myositis ossificans, (2) intramuscular seroma and (3) trochanteric (hip) bursitis. Normal reference value (no injury) was obtained from the contra lateral not injured limb at a mirror-like location of the injury. The relative variations resistance (R) and reactance (Xc) at the time of injury was confronted with the not injured values. Relative variations between acute measurements and post medication ones on intramuscular seroma and bursitis have been computed. In intramuscular seroma and trochanteric bursitis we have obtained a percent of change between injury data and after medical intervention. On myositis ossificans, localized BIA showed a 7-8 % decrease in Xc whereas the percent of change of R was negligible (1 %). These percent of changes are in concordance with histological evidence. In the case of a presence of seroma or the lower thigh and trochanteric bursitis, the soft tissue cavity accumulates fluid. Post-injury localized BIA, relative with respect to non-injured side, confirmed sizeable soft tissue destruction evidenced by 50 % decrease of Xc and 24-31 % decrease of R due to interstitial fluid accumulation. Once the seroma and the blood in the bursitis was removed the localized the immediate post-injury BIA parameters increased as follows: a) intramuscular seroma + 10 % on R and + 74 % of Xc; b) trochanteric bursitis + 20 % of R and +24 % of Xc. Localized BIA other than classifying soft tissue injuries, can be useful to understand the pathophysiology and structural impairments of other kind of injuries and to understand their behavior.

Myositis Ossificans

Myositis ossificans is a self-limiting, benign ossifying lesion that can affect any type of soft tissue, including subcutaneous fat, tendons, and nerves. It is most commonly found in muscle as a solitary lesion. Ossifying soft-tissue lesions historically have been inconsistently classified. Fundamentally, myositis ossificans can be categorized into nonhereditary and hereditary types, with the latter being a distinct entity with a separate pathophysiology and treatment approach. The etiology of myositis ossificans is variable; however, clinical presentation generally is characterized by an ossifying soft-tissue mass. Advanced cross-sectional imaging alone can be nonspecific and may appear to be similar to more sinister etiologies. Therefore, the evaluation of a suspicious soft-tissue mass often necessitates multiple imaging modalities for accurate diagnosis. When imaging is indeterminate, biopsy may be required for a histologic diagnosis. However, histopathology varies based on stage of evolution. The treatment of myositis ossificans is complex and is often made in a multidisciplinary fashion because accurate diagnosis is fundamental to a successful outcome.

Myositis ossificans of the quadriceps femoris in a soccer player

A young soccer player was diagnosed with myositis ossificans 6 weeks after a muscle strain in the right thigh. Radiographic and sonographic investigations initially helped to confirm diagnosis and later supported clinical improvement. We present our approach to the case and discuss pathophysiology, prevention and treatment of this rare condition.

Bilateral deltoid myositis ossificans in a weightlifter using anabolic steroids

A 40-year-old male weightlifter presented with a 6-month history of a painless mass in the right deltoid. He had no history of trauma to the shoulder other than an arthroscopic rotator cuff repair a few weeks earlier. Physical examination showed a firm, nontender mass located longitudinally and coinciding with the deltoid, measuring 12×14×4 cm. There was no limitation in range of motion or functioning. Magnetic resonance imaging (MRI) and computed tomography (CT) scans suggested a lobulated, heterogeneous mass with multiple areas of calcification that raised suspicion for soft tissue sarcoma vs myositis ossificans. Marginal resection of the soft tissue mass was performed, and pathologic studies confirmed the diagnosis of xanthogranulomatous myositis ossificans with dystrophic calcifications and central cystic degeneration. At 2-week follow-up, the patient had improved range of motion and pain, but he noted a second soft tissue mass in the left deltoid. The MRI and CT scans showed a 10.5×16×3.4-cm linear, lobulated lesion with multiple calcifications, similar in appearance to the contralateral deltoid. The patient admitted to frequently injecting anabolic steroids into his deltoids. Because the patient was asymptomatic on the left side and the MRI appearance of the left deltoid mass was similar to that of the myositis ossificans seen on the right side, the patient opted for nonsurgical treatment. This is a rare case of myositis ossificans occurring bilaterally in the deltoids after repeated injections of anabolic steroids. There is currently no known association between anabolic steroids and myositis ossificans. This condition often mimics malignant neoplasms, illustrating the necessity of resection for diagnostic confirmation.

The inhibition effects of insulin on BMP2-induced muscle heterotopic ossification

Bone morphogenetic proteins (BMPs) play an important role in regulating osteoblastic differentiation and bone formation. But the diffuse of BMPs into muscle tissues around bone injury sites often leads to heterotopic ossification, which has been regarded as one of major side-effects of BMP implementation in bone defect patients. It raises great demands for exploring effective methods that preventing BMP-induced heterotopic ossification while not interrupting the osteoinductive activity of BMPs for in situ bone defect repair. Here we found insulin, a positive regulator for bone regeneration, inhibited BMP2-induced muscle heterotopic ossification by suppressing the expression of bone transcription factor Osterix. By analyzing downstream molecules of insulin pathway, we found AKT/mTOR/GSK3 signaling was responsible for the inhibition of insulin on BMP2-induced ossification, and GSK3 inhibitor SB216763 attenuated BMP2-induced muscle heterotopic ossification. The data might shed light on developing effective clinical therapy for inhibiting muscle heterotopic ossification when BMPs were used bone defect repair.

Muscle injuries in athletes: enhancing recovery through scientific understanding and novel therapies

Context:

Muscle injuries are extremely common in athletes and often produce pain, dysfunction, and the inability to return to practice or competition. Appropriate diagnosis and management can optimize recovery and minimize time to return to play.

Evidence Acquisition:

Contemporary papers, both basic science and clinical medicine, that investigate muscle healing were reviewed. A Medline/PubMed search inclusive of years 1948 to 2012 was performed.

Results:

Diagnosis can usually be made according to history and physical examination for most injuries. Although data are limited, initial conservative management emphasizing the RICE principles and immobilization of the extremity for several days for higher grade injuries are typically all that is required. Injection of corticosteroids may clinically enhance function after an acute muscle strain. Additional adjunctive treatments (nonsteroidal anti-inflammatory drugs, platelet-rich plasma, and others) to enhance muscle healing and limit scar formation show promise but need additional data to better define their roles.

Conclusion:

Conservative treatment recommendations will typically lead to successful outcomes after a muscle injury. There is limited evidence to support most adjunctive treatments.

Traumatic injuries of thigh and calf muscles in athletes: role and clinical relevance of MR imaging and ultrasound

Objectives

Magnetic resonance (MR) imaging and ultrasound have become valuable tools for evaluation of traumatic muscle injuries in athletes. Common athletic injuries include strain, contusion and avulsion, which are characterised by muscle fibre disruption, intramuscular haemorrhagic dissection, haematoma at the musculotendinous junction, and perifascial blood or haematoma.

Methods

MR imaging may allow clinicians to predict the time required before athletes can return to competition and the risk of injury recurrence.

Results

Fluid-sensitive MR sequences, e.g., fat-suppressed T2-weighted or proton density-weighted turbo spin echo (TSE), and short-tau inversion recovery (STIR) sequences are suitable for detecting oedematous changes in the musculotendinous unit, and for delineating intramuscular or perifascial fluid collections or haematoma. T1-weighted spin echo sequences are used to visualise atrophy and fatty infiltration and to differentiate between haemorrhage/haematoma and oedema. While ultrasound may play a role as an adjunctive imaging method, it is less accurate than MR images for assessing the extent of the injury and it cannot differentiate between new and old injuries.

Conclusions

In this pictorial review, imaging features of lower extremity muscle injuries including strain, contusion and avulsion are reviewed, focusing on MR and ultrasound imaging findings after initial injury and during follow-up, and their relevance in clinical practice is discussed.

Teaching points

• MR imaging may allow clinicians to predict time required before athletes can return to competition

• Fluid-sensitive MR sequences are suitable for detecting oedematous changes in the muscles

• T1-weighted sequences are used to differentiate between haemorrhage/haematoma and oedema.

• Ultrasound can also be used but is less accurate than MR imaging for assessing the extent of the injury

Myositis ossificans circumscripta of the triceps due to overuse in a female swimmer

Myositis ossificans is a rare condition characterized by non-neoplastic heterotopic bone formation in soft tissue and skeletal muscle. It is a benign and often self-limiting disease with no need for surgery. Here, we describe a young female swimmer with myositis ossificans circumscripta of the triceps due to overuse. Because of the benign character of the lesion, conservative treatment was initiated with rest and anti-inflammatory drugs. She obtained complete resolution after 6 months and was able to return to normal sporting activities. Myositis ossificans circumscripta is a rare benign lesion with an excellent prognosis. Most lesions in athletes occur due to contusions or strains; however, overuse is now described as well. Spontaneous resolution is seen in almost all cases. Cases in which, despite conservative treatment, a painful mass persists, surgical excision can be considered.

Sensory nerve induced inflammation contributes to heterotopic ossification

Heterotopic ossification (HO), or bone formation in soft tissues, is often the result of traumatic injury. Much evidence has linked the release of BMPs (bone morphogenetic proteins) upon injury to this process. HO was once thought to be a rare occurrence, but recent statistics from the military suggest that as many as 60% of traumatic injuries, resulting from bomb blasts, have associated HO. In this study, we attempt to define the role of peripheral nerves in this process. Since BMP2 has been shown previously to induce release of the neuroinflammatory molecules, substance P (SP) and calcitonin gene related peptide (CGRP), from peripheral, sensory neurons, we examined this process in vivo. SP and CGRP are rapidly expressed upon delivery of BMP2 and remain elevated throughout bone formation. In animals lacking functional sensory neurons (TRPV1(-/-) ), BMP2-mediated increases in SP and CGRP were suppressed as compared to the normal animals, and HO was dramatically inhibited in these deficient mice, suggesting that neuroinflammation plays a functional role. Mast cells, known to be recruited by SP and CGRP, were elevated after BMP2 induction. These mast cells were localized to the nerve structures and underwent degranulation. When degranulation was inhibited using cromolyn, HO was again reduced significantly. Immunohistochemical analysis revealed nerves expressing the stem cell markers nanog and Klf4, as well as the osteoblast marker osterix, after BMP2 induction, in mice treated with cromolyn. The data collectively suggest that BMP2 can act directly on sensory neurons to induce neurogenic inflammation, resulting in nerve remodeling and the migration/release of osteogenic and other stem cells from the nerve. Further, blocking this process significantly reduces HO, suggesting that the stem cell population contributes to bone formation.

Biologic scaffold remodeling in a dog model of complex musculoskeletal injury

BACKGROUND

Current treatment principles for muscle injuries with volumetric loss have been largely derived from empirical observations. Differences in severity or anatomic location have determinant effects on the tissue remodeling outcome. Biologic scaffolds composed of extracellular matrix (ECM) have been successfully used to restore vascularized, innervated, and contractile skeletal muscle in animal models but limited anatomic locations have been evaluated. The aim of this study was to determine the ability of a xenogeneic ECM scaffold to restore functional skeletal muscle in a canine model of a complex quadriceps injury involving bone, tendon, and muscle.

MATERIALS AND METHODS

Sixteen dogs were subjected to unilateral resection of the distal third of the vastus lateralis and medial half of the distal third of the vastus medialis muscles including the proximal half of their associated quadriceps tendon. This defect was replaced with a biologic scaffold composed of small intestinal submucosa extracellular matrix (SIS-ECM) and the remodeling response was evaluated at 1, 2, 3, and 6 mo (N = 4 per group).

RESULTS

The initial remodeling process followed a similar pattern to other studies of ECM-mediated muscle repair with rapid vascularization and migration of myoblasts into the defect site. However, over time the remodeling response resulted in the formation of dense collagenous tissue with islands of muscle in the segments of the scaffold not in contact with bone, and foci of bone and cartilage in the segments that were adjacent to the underlying bone.

CONCLUSIONS

SIS-ECM was not successful at restoring functional muscle tissue in this model. However, the results also suggest that SIS-ECM may have potential to promote integration of soft and boney tissues when implanted in close apposition to bone.

Cytokine expression in muscle following traumatic injury

Heterotopic ossification (HO) occurs at a high frequency in severe orthopaedic extremity injuries; however, the etiology of traumatic HO is virtually unknown. Osteogenic progenitor cells have previously been identified within traumatized muscle. Although the signaling mechanisms that lead to this dysregulated differentiation pathway have not been identified, it is assumed that inflammation and fibrosis, which contribute to an osteoinductive environment, are necessary for the development of HO. The hypothesis of this study was that cytokines related to chronic inflammation, fibrogenesis, and osteogenesis become up-regulated following severe muscle trauma where HO forms. Classification of these cytokines by their differential expression relative to control muscle will provide guidance for further study of the mechanisms leading to HO. Real-time RT-PCR analysis revealed no significant up-regulation of cytokines typically associated with HO (e.g., BMP-4, as observed in the genetic form of HO, fibrodysplasia ossificans progressiva). Instead, the cytokine gene expression profile associated with the traumatized muscle included up-regulation of cytokines associated with osteogenesis and fibrosis (i.e., BMP-1 and TGF-β(1)). Using immunohistochemistry, these cytokines were localized to fibroproliferative lesions, which have previously been implicated in HO. This study identifies other cell and tissue-level interactions in traumatized muscle that should be investigated further to better define the etiology of HO.

BMP-9-induced muscle heterotopic ossification requires changes to the skeletal muscle microenvironment

Heterotopic ossification (HO) is defined as the formation of bone inside soft tissue. Symptoms include joint stiffness, swelling, and pain. Apart from the inherited form, the common traumatic form generally occurs at sites of injury in damaged muscles and is often associated with brain injury. We investigated bone morphogenetic protein 9 (BMP-9), which possesses a strong osteoinductive capacity, for its involvement in muscle HO physiopathology. We found that BMP-9 had an osteoinductive influence on mouse muscle resident stromal cells by increasing their alkaline phosphatase activity and bone-specific marker expression. Interestingly, BMP-9 induced HO only in damaged muscle, whereas BMP-2 promoted HO in skeletal muscle regardless of its state. The addition of the soluble form of the ALK1 protein (the BMP-9 receptor) significantly inhibited the osteoinductive potential of BMP-9 in cells and HO in damaged muscles. BMP-9 thus should be considered a candidate for involvement in HO physiopathology, with its activity depending on the skeletal muscle microenvironment.

Biopsy diagnosis of early myositis ossificans without radiologic evidence of calcification: success of early surgical resection

Myositis ossificans is an uncommon disorder, which is commonly mistaken for a malignant muscle disease before histologic examination. Trauma is the most common cause of the acquired form of the disease; however, atraumatic cases have been described. The factors responsible for extraosseous ossification, such as the role of bone morphogenic protein 4, are becoming better understood. However, treatment of the disorder is not well defined. We present a case of atraumatic myositis ossificans in a 16-year-old girl that was associated with severe pain and lacked radiologic evidence of calcification. She underwent early surgical excision, resulting in immediate resolution of her symptoms. This case demonstrates that waiting for complete maturation of the lesion may not be necessary.

Diagnosis and management of quadriceps strains and contusions

Injuries to the quadriceps muscle group occur frequently in sports and athletic activities. Muscle strains and contusions constitute the majority of these injuries. The clinical presentation and assessment of quadriceps strains and contusions are reviewed along with discussion of appropriate imaging used in diagnosis. Treatment protocols for acute injuries are reviewed including rehabilitation techniques frequently utilized during recovery. Special consideration is given to discussing the criteria for return to sports for athletes after injury. Myositis ossificans is a potentially disabling complication from quadriceps contusions and risk factors, prevention, and treatment are reviewed.

BIOMECHANICAL AND HISTOLOGICAL ANALYSIS OF THE GASTROCNEMIUS IN RATS SUBJECTED TO MUSCLE INJURY AND TREATMENT WITH LOW-LEVEL LASER THERAPY

Objective: To mechanically and histologically evaluate the application of low-level laser therapy to the reparative process on lesions caused by impact on the gastrocnemius muscles of rats. Methods: 45 female Wistar rats were divided into three groups (n=15/ group): C (control, no lesion), ML (muscle lesion) and ML-L (muscle lesion and laser therapy). The experimental muscle lesion was produced by letting a 250 g load drop from a height of 30 cm, directly onto the muscle. The animals in the ML-L group were subjected to application of 960 nm laser, 2 J/cm², on the lesion site, for three days, twice a day. Mechanical tests were performed on an Emic^® universal testing machine. Results: The mean values for the maximum force were: 35.70 (± 2.69) N in group C, 31.77 (± 2.59) N in group ML and 34.36 (± 3.63) N in group ML-L, with a statistically significant difference between groups C and ML (p < 0.05). The mean values for relative stiffness were: 3.75 (± 0.98) N/mm in group C, 3.84 (± 0.32) N/mm in group ML and 4.43 (± 0.68) N/mm in group ML-L, with no statistically significant differences (p>0.05). Histological analysis showed the presence of blood vessels in group ML-L and hematomas during the repair process. Conclusion: Laser therapy had a positive effect on the regeneration process of the muscle injury.