From brain to bone: evidence for the release of osteogenic humoral factors after traumatic brain injury

Mechanism of traumatic heterotopic ossification: In search of injury-induced osteogenic factors

Heterotopic ossification (HO) is a pathological condition of abnormal bone formation in soft tissue. Three factors have been proposed as required to induce HO: (a) osteogenic precursor cells, (b) osteoinductive agents and (c) an osteoconductive environment. Since Urist's landmark discovery of bone induction in skeletal muscle tissue by demineralized bone matrix, it is generally believed that skeletal muscle itself is a conductive environment for osteogenesis and that resident progenitor cells in skeletal muscle are capable of differentiating into osteoblast to form bone. However, little is known about the naturally occurring osteoinductive agents that triggered this osteogenic response in the first place. This article provides a review of the emerging findings regarding distinct types of HO to summarize the current understanding of HO mechanisms, with special attention to the osteogenic factors that are induced following injury. Specifically, we hypothesize that muscle injury‐induced up‐regulation of local bone morphogenetic protein‐7 (BMP‐7) level, combined with glucocorticoid excess‐induced down‐regulation of circulating transforming growth factor‐β1 (TGF‐β1) level, could be an important causative mechanism of traumatic HO formation.

Traumatic brain injury enhances the formation of heterotopic ossification around the hip: an animal model study

INTRODUCTION

The incidence of heterotopic ossification (HO) is at its highest when trauma of the hip or pelvis concurs with traumatic brain injury (TBI). The pathogenic mechanisms underlying the neurogenic enhancement of the formation of HO remain, however, poorly understood. Hence, the goal of the present study was to develop a novel small animal model that combines hip and brain trauma that can prove the enhancement of HO around the hip after TBI.

MATERIALS AND METHODS

Forty male Wistar rats were divided into four groups, to undergo hip surgery alone (group 1), hip surgery + moderate TBI (group 2), hip surgery + severe TBI (group 3) and only severe TBI (group 4). The femoral canal was reamed up to 2 mm and a muscle lesion was made to simulate hip surgery. An established controlled cortical impact model was used to create a TBI. Twelve weeks after surgery, the hip with the proximal half of the femur and the pelvic bone was removed and subjected to micro-computed tomography (µCT) analysis. A quantitative analysis using a modified Brooker score as well as a quantitative analysis using a bone-to-tissue ratio was used.

RESULTS

No HO could be found in all the ten animals that did not undergo hip surgery (group 4). In the animals that did undergo surgery to the hip, no HO was found in only one animal (group 1). All the other animals developed HO. In this study, significantly more HO was found in animals that underwent an additional severe TBI.

CONCLUSION

The newly developed rat model, with a combined hip and brain trauma, showed an enhancement of the HO formation around the hip after severe TBI.

Crosstalk of Brain and Bone-Clinical Observations and Their Molecular Bases

As brain and bone disorders represent major health issues worldwide, substantial clinical investigations demonstrated a bidirectional crosstalk on several levels, mechanistically linking both apparently unrelated organs. While multiple stress, mood and neurodegenerative brain disorders are associated with osteoporosis, rare genetic skeletal diseases display impaired brain development and function. Along with brain and bone pathologies, particularly trauma events highlight the strong interaction of both organs. This review summarizes clinical and experimental observations reported for the crosstalk of brain and bone, followed by a detailed overview of their molecular bases. While brain-derived molecules affecting bone include central regulators, transmitters of the sympathetic, parasympathetic and sensory nervous system, bone-derived mediators altering brain function are released from bone cells and the bone marrow. Although the main pathways of the brain-bone crosstalk remain ‘efferent’, signaling from brain to bone, this review emphasizes the emergence of bone as a crucial ‘afferent’ regulator of cerebral development, function and pathophysiology. Therefore, unraveling the physiological and pathological bases of brain-bone interactions revealed promising pharmacologic targets and novel treatment strategies promoting concurrent brain and bone recovery.

Investigating the incidence and magnitude of heterotopic ossification with and without joints involvement in patients with a limb fracture and mild traumatic brain injury

Objectives

This study seeks to evaluate the incidence rate of heterotopic ossification (HO) formation in patients afflicted by an isolated limb fracture (ILF) and a concomitant mild traumatic brain injury (mTBI).

Methods

The current study is an observational study including ILF patients with or without a concomitant mTBI recruited from an orthopedic clinic of a Level 1 Trauma Hospital. Patients were diagnosed with a mTBI according to the American Congress of Rehabilitation Medicine (ACRM) criteria. Radiographs taken on average 3 months post-trauma were analyzed separately by two distinct specialists for the presence of HO proximally to the fracture site (joints or extra joints). Both raters referred to Brooker's and Della's Valle's classification to establish signs of HO. First, analyses were conducted for the full sample. Secondly, a matched cohort was used in order to control for specific factors, namely age, sex, type of injury, and time elapsed between the accident and the analyzed radiograph.

Results

The full sample included a total of 183 patients with an ILF (94 females; 47.5 years old), of which 50 had a concomitant mTBI and 133 without. Radiographic evidence of HO was significantly higher in patients with an ILF and a mTBI compared to ILF patients (X² = 6.50; p = 0.01). The matched cohort consisted of 94 participants (i.e.; 47 patients from the ILF + mTBI group and 47 patients from the ILF group). Again, ILF + mTBI patients presented significantly higher rates of HO signs in comparison to ILF patients (X² = 3.69; p = 0.04). Presence of HO was associated with prolonged delays to return to work (RTW) only in ILF + mTBI patients (F = 4.055; p = 0.05) but not in ILF patients (F = 0.823; p = 0.37).

Conclusions

Study findings suggest that rates of HO are significantly higher proximally to fracture sites when ILF patients sustain a concomitant mTBI, even after controlling for factors known to influence HO. Moreover, results show that HO is associated with a prolonged RTW only in ILF patients with a concomitant mTBI but not in ILF-only patients. The impact of mTBI on HO formation warrants further attention to detect early signs of HO, to identify shared physiopathological mechanisms and, ultimately, to design targeted therapies.

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Rates of HO are significantly higher in patients with a fracture and a mTBI compared to patients with a fracture only.

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Factors such as sex, age, joint involvement, and surgical procedures were unrelated to the detection of signs of HO

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Presence of HO negatively impacted RTW delays in patients with a concomitant mTBI

Risk factors for complications and adverse outcomes in polytrauma patients with associated upper extremity injuries

BACKGROUND

In terms of upper extremity fractures by patients with multiple injuires, a lot of studies have assessed the functional outcome following trauma to have less favorable outcomes in regards to functional recovery. We tested the hypothesis that differences in clinical outcome occur between shaft and articular injuries of the upper extremity, when patients that sustained neurologic deficits (e.g. brachial plexus lesions) are excluded.

METHODS

We involved Patients with isolated or combined upper extremity fracture, ISS > 16 in a level one trauma center. The follow up was at least 10 years after the initial injury. Both clinical examination (range of motion, instability, contractures, peripheral nerve damage) and radiographic analysis were carried out. We evaluated also the development of heterotopic ossifications. To analyse patients were subdivided into 3 different subgroups (articular [IA], shaft [IS], and combined [C]).

RESULTS

A statistically significant difference was found when ROM was compared between Group IS and C (p = 0.012), for contractures between Groups IA and C (p = 0.009) and full muscle elbow forces between Groups IS and C (p = 0.005) and Group IA and IS (p = 0.021). There was a significantly increased incidence in heterotopic ossifications when articular involvement was present. This applied for the isolated (p < 0.02) and the combined group (Group C vs Group IS, p = 0.003).When Brooker type I/II in group IA and Brooker types III/IV were combined, there was a significant difference (p < 0.001). In group IA (n = 1) and in group C (n = 6), HO developed or worsened after revision surgery, all of which were performed for malunion or nonunion.

CONCLUSIONS

In this study, patients with isolated shaft fractures of the upper extremity tend to have a more favorable outcome in comparison with combined to isolated articular fractures in terms of range of motion, pain and the ability to use the arm for everyday activities.In the clinical practice of the treatment of polytraumatized patients with upper extremity injuries, we feel that the relevance of these injuries should not be underestimated. They are especially prone to development of heterotopic ossifications, thus requiring prophylactic measures, if necessary. As their incidence increases with the rate of reoperations, we feel that even during initial care, meticulous surgery is required to avoiding the necessity of revision surgeries. Similar to injuries below the knee, upper extremity injuries, should be treated to avoid any functional disability.

A survey of proteomic biomarkers for heterotopic ossification in blood serum

Background

Heterotopic ossification (HO) is a significant problem for wounded warriors surviving high-energy blast injuries; however, currently, there is no biomarker panel capable of globally characterizing, diagnosing, and monitoring HO progression. The aim of this study was to identify biomarkers for HO using proteomic techniques and blood serum.

Methods

Isobaric tags for relative and absolute quantitation (iTRAQ) was used to generate a semi-quantitative global proteomics survey of serum from patients with and without heterotopic ossification. Leveraging the iTRAQ data, a targeted selection reaction monitoring mass spectrometry (SRM-MS) assay was developed for 10 protein candidates: alkaline phosphatase, osteocalcin, alpha-2 type I collagen, collagen alpha-1(V) chain isoform 2 preprotein, bone sialoprotein 2, phosphatidate phosphatase LPIN2, osteomodulin, protein phosphatase 1J, and RRP12-like protein.

Results

The proteomic survey of serum from both healthy and disease patients includes 1220 proteins and was enriched for proteins involved in the response to elevated platelet Ca⁺², wound healing, and extracellular matrix organization. Proteolytic peptides from three of the ten SRM-MS proteins, osteocalcin preprotein, osteomodulin precursor, and collagen alpha-1(v) chain isoform 2 preprotein from serum, are potential clinical biomarkers for HO.

Conclusions

This study is the first reported SRM-MS analysis of serum from individuals with and without heterotopic ossification, and differences in the serum proteomic profile between healthy and diseased subjects were identified. Furthermore, our results indicate that normal wound healing signals can impact the ability to identify biomarkers, and a multi-protein panel assay, including osteocalcin preproprotein, osteomodulin precursor, and collagen alpha-1(v) chain isoform 2 preprotein, may provide a solution for HO detection and monitoring.

Electronic supplementary material

The online version of this article (doi:10.1186/s13018-017-0567-2) contains supplementary material, which is available to authorized users.

Incidence and clinical relevance of heterotopic ossification after internal fixation of acetabular fractures: retrospective cohort and case control study

Objective

The aim of the study was to evaluate predictors and clinical relevance of heterotopic ossification (HO) in patients treated for acetabular fractures in a tertiary referral centre.

Patients and methods

The study is a retrospective cohort study with a nested case–control study. All patients treated with internal fixation of acetabular fractures from January 2004 to October 2013. Ninety patients had postoperative imaging available at 6 and 12 months postoperatively and received no prophylaxis. Plain radiographs were used to grade HO. The Hip disability and Osteoarthritis Outcome Score (HOOS) was used to compare outcomes between patients suffering from HO with patients who did not.

Results

Sixteen patients (17.7%) suffered from HO. According to the Brooker classification, 5 had class I, 4 class II, 3 class III and 4 class IV HO. Traumatic brain injury (TBI) was the only significant risk factor for developing HO (odds ratio (OR) 8.6, 95% confidence interval (CI) (1.693–43.753), p = 0.014). The HO rate in patients with an anterior (ilioinguinal) or posterior (Kocher-Langenbeck) surgical approach was 20% and 21% respectively, and the HO rate in patients with a combined approach was much lower at 11%. Neither fracture type nor gender nor age increased the risk of HO significantly. The outcome measured by HOOS was not significantly different between patients with HO and patients in the control group. Patients with HO Brooker class II–IV had slightly lower (effect estimate +4.25, 95% CI (−10.2 to +12.10), p = 0.220) HOOS compared to the majority of the control group.

Conclusion

A very low rate of HO was found compared to the HO rates described in other studies with similar patient cohorts who received prophylaxis. Based on our findings and the current literature, we do not recommend giving prophylaxis against HO to patients after internal fixation of acetabular fractures.

Systemic manifestations of traumatic brain injury

Traumatic brain injury (TBI) affects functioning of various organ systems in the absence of concomitant non-neurologic organ injury or systemic infection. The systemic manifestations of TBI can be mild or severe and can present in the acute phase or during the recovery phase. Non-neurologic organ dysfunction can manifest following mild TBI or severe TBI. The pathophysiology of systemic manifestations following TBI is multifactorial and involves an effect on the autonomic nervous system, involvement of the hypothalamic-pituitary axis, release of inflammatory mediators, and treatment modalities used for TBI. Endocrine dysfunction, electrolyte imbalance, and respiratory manifestations are common following TBI. The influence of TBI on systemic immune response, coagulation cascade, cardiovascular system, gastrointestinal system, and other systems is becoming more evident through animal studies and clinical trials. Systemic manifestations can independently act as risk factors for mortality and morbidity following TBI. Some conditions like neurogenic pulmonary edema and disseminated intravascular coagulation can adversely affect the outcome. Early recognition and treatment of systemic manifestations may improve the clinical outcome following TBI. Further studies are required especially in the field of neuroimmunology to establish the role of various biochemical cascades, not only in the pathophysiology of TBI but also in its systemic manifestations and outcome.

Chiropractic care of a patient with neurogenic heterotopic ossification of the anterior longitudinal ligament after traumatic brain injury: a case report

OBJECTIVE

The purpose of this case report is to describe the use of chiropractic care for a patient with neurogenic heterotopic ossification of the anterior longitudinal ligament in the cervical spine and soft tissues of the right hip after a traumatic brain injury and right femur fracture.

CLINICAL FEATURES

A 25-year-old military officer was referred to a hospital-based chiropractic clinic with complaints of pain and stiffness of the neck and back along with reduced respiratory excursions that began several months after a motor vehicle accident in which he had a traumatic brain injury. The patient had a fractured right femur from the accident, which had since been treated surgically, but had complications of heterotopic ossification in the soft tissues of the hip. His overall pain level was 3 of 10 on a verbal pain scale during use of oxycodone HCL/acetaminophen. Chest excursion was initially measured at .5 cm.

INTERVENTION AND OUTCOME

With the intent to restore respiratory chest motion and to reduce the patient's back and neck pain, the patient was placed on a program of chiropractic and myofascial manipulation, exercise therapy, and respiratory therapy. After a year of care, the patient rated overall pain at 3 of 10 verbal pain scale level but was no longer taking medications for pain and an increase in respiratory chest excursions measured at 3.5 cm.

CONCLUSION

This case demonstrated that chiropractic treatment provided benefit to a patient with heterotopic ossification concurrent with musculoskeletal pain.

The negative impact of traumatic brain injury (TBI) on bone in a mouse model

INTRODUCTION

While it is well established that the brain produces hypothalamic hormones and neuropeptides that influence skeletal metabolism, the impact of traumatic brain injury (TBI) on bone is unknown. Based on the recognition from clinical studies that there is an association between TBI and long-term hypothalamic pituitary dysfunction, it was hypothesized that TBI exerts a negative impact on skeletal growth and maintenance.

METHODS

To test the hypothesis, this study employed a repetitive weight drop model for TBI. Four impacts were applied for four consecutive days on 5-week old female C57BL/6 J mice. Bone measurements were taken 2 weeks after the first impact.

RESULTS

Bone mineral content (BMC), bone area (B area) and bone mineral density (BMD) in the total body were reduced by 14.5%, 9.8% and 5.2%, respectively, in the impacted vs. control mice. There was a 17.1% reduction in total volumetric BMD (vBMD) and a 4.0% reduction in material vBMD in cortical bone. In trabecular bone, there was a 44.0% reduction in BV/TV. Although there was no change in the cross-sectional bone size, the tibial growth plate and the tibia itself were shortened.

CONCLUSION

The repetitive animal TBI model produced an immediate, strong negative impact on bone mass acquisition in young mice.

Leptin's effect on accelerated fracture healing after traumatic brain injury

OBJECTIVE

To investigate mechanisms behind the faster rehabilitation of limb fractures when associated with traumatic brain injury (TBI).

METHODS

New Zealand rabbits were divided into TBI group and sham-operation group for four studies as follows: (1) blood and cerebrospinal fluid (CSF) were drawn on days 1, 3, and 7 to demonstrate changes in serum leptin, growth hormone (GH), insulin-like growth factor 1 (IGF-1), and CSF leptin; (2) bone defection was created by drilling in the tibial bone and either leptin or normal saline was injected into rabbit's cerebellomedullary cistern. X-ray was taken at 1 days, 2 weeks, and 5 weeks and evaluated by criteria to determine rate of bone healing; (3) FITC-labeled rabbit leptin was injected into TBI and sham-operation groups, and frozen sections of rabbit brain were observed to identify differences in central nervous system (CNS) leptin by fluorescence; (4) polymerase chain reaction (PCR) was used to evaluate the expression of leptin production by brain tissue.

RESULTS

Serum and CSF leptin, GH, and IGF-1 concentrations were found to be higher in the TBI group than the sham-operation group at days 1, 3, and 7 (P<0·05). CSF leptin of the TBI group was positively correlated with serum leptin on day 1 (P<0·05), and positively correlated with GH and IGF-1 on days 3 and 7 (P<0·05). X-ray criteria demonstrated that leptin administration caused significantly faster healing calluses at 3 and 5 weeks as compared to control animals (P<0·05). FITC-labeled leptin study demonstrated that TBI animals had stronger expression of leptin in the brain than sham-operated animals. However, PCR of brain tissue leptin showed no significant differences between TBI and sham-operated animals in the expression of leptin.

CONCLUSIONS

Our study suggests that increased CSF leptin, likely from blood-brain barrier breakdown, combined with elevated serum GH and IGF-1 after TBI, leads to accelerated fracture healing.

Effect of rat brain tissue extracts on osteoblast proliferation and differentiation

PURPOSE

The reason for enhanced fracture healing in traumatic brain injury patients is not clearly understood. It is possible that factors inherent in the brain passing through the blood-brain barrier to the peripheral circulation, or a disruption of central nervous system (CNS) control of the sympathetic nervous system (SNS), stimulates the process of fracture healing.

METHODS

In this study, we assessed proliferation [using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay] and differentiation [using alkaline phosphatase (ALP)] in rat osteoblasts incubated with gray matter or other tissue extracts with and without the addition of an α- or β-adrenergic receptor blocker (phentolamine or propranolol).

RESULTS

Gray matter extract from normal brain caused a dose-dependent increase in osteoblast proliferation and differentiation. Serum from normal rats enhanced differentiation but not proliferation. Alpha-receptor blockade had no effect on proliferation or differentiation. Beta-receptor blockade caused a partial, but statistically significant, decrease in gray matter stimulation of osteoblast differentiation.

CONCLUSION

The results of this study indicate that gray matter extract from normal brain increases osteoblast proliferation and differentiation and that β receptors may be involved in differentiation under these conditions.

Troublesome heterotopic ossification after central nervous system damage: a survey of 570 surgeries

Background

Heterotopic ossification (HO) is a frequent complication after central nervous system (CNS) damage but has seldom been studied. We aimed to investigate features of HO for the first time in a large sample and the rate of early recurrence of HO in terms of the time of surgery.

Methodology/Principal Findings

We retrospectively analyzed data from an anonymous prospective survey of patients undergoing surgery between May 1993 and November 2009 in our institution for troublesome HO related to acquired neurological disease. Demographic and HO characteristics and neurological etiologies were recorded. For 357 consecutive patients, we collected data on 539 first surgeries for HO (129 surgeries for multiple sites). During the follow-up, recurrences requiring another surgery appeared in 31 cases (5.8% [31/539]; 95% confidence interval [CI]: 3.8%–7.8%; 27 patients). Most HO requiring surgery occurred after traumatic brain injury (199 patients [55.7%]), then spinal cord injury (86 [24.0%]), stroke (42 [11.8%]) and cerebral anoxia (30 [8.6%]). The hip was the primary site of HO (328 [60.9%]), then the elbow (115 [21.3%]), knee (77 [14.3%]) and shoulder (19 [3.5%]). For all patients, 181 of the surgeries were performed within the first year after the CNS damage, without recurrence of HO. Recurrence was not associated with etiology (p = 0.46), sex (p = 1.00), age at CNS damage (p = 0.2), multisite localization (p = 0.34), or delay to surgery (p = 0.7).

Conclusions/Significance

In patients with CNS damage, troublesome HO and recurrence occurs most frequently after traumatic brain injury and appears frequently in the hip and elbow. Early surgery for HO is not a factor of recurrence.

Traumatic brain injury: a disease process, not an event

Traumatic brain injury (TBI) is seen by the insurance industry and many health care providers as an "event." Once treated and provided with a brief period of rehabilitation, the perception exists that patients with a TBI require little further treatment and face no lasting effects on the central nervous system or other organ systems. In fact, TBI is a chronic disease process, one that fits the World Health Organization definition as having one or more of the following characteristics: it is permanent, caused by non-reversible pathological alterations, requires special training of the patient for rehabilitation, and/or may require a long period of observation, supervision, or care. TBI increases long-term mortality and reduces life expectancy. It is associated with increased incidences of seizures, sleep disorders, neurodegenerative diseases, neuroendocrine dysregulation, and psychiatric diseases, as well as non-neurological disorders such as sexual dysfunction, bladder and bowel incontinence, and systemic metabolic dysregulation that may arise and/or persist for months to years post-injury. The purpose of this article is to encourage the classification of TBI as the beginning of an ongoing, perhaps lifelong process, that impacts multiple organ systems and may be disease causative and accelerative. Our intent is not to discourage patients with TBI or their families and caregivers, but rather to emphasize that TBI should be managed as a chronic disease and defined as such by health care and insurance providers. Furthermore, if the chronic nature of TBI is recognized by government and private funding agencies, research can be directed at discovering therapies that may interrupt the disease processes months or even years after the initiating event.

Heterotopic ossification following cardiac arrest and hypoxic brain damage

Aims

Heterotopic bone can cause restriction of movement when deposited in the soft tissues around joints. Neurogenic heterotopic ossification may follow brain injury. This article describes research into the incidence of heterotopic ossification after brain injury, and its impact on rehabilitation.

Methods

Thirty-nine patients who were admitted to the rehabilitation unit of University Hospital Bydgoszcz, Poland, after hypoxic brain injury due to cardiac arrest, were examined.

Findings

Six patients were identified as having developed heterotopic bone around one or more joints causing limitation of movement and delay in the rehabilitation process.

Conclusions

Heterotopic ossification occurs in up to 15% of patients following hypoxic brain injury. The development of the condition may often be missed clinically, and can hinder rehabilitation.

Poliomyelitis causing TMJ ankylosis?--report of two intriguing cases

INTRODUCTION

Temporomandibular joint (TMJ) ankylosis is one of the common diseases which affect the TMJ especially in children. We are reporting two rare cases of TMJ ankylosis which occurred along with poliomyelitis and which are not reported in literature so far.

DISCUSSION

In this article, we discussed about the most probable causes which resulted in TMJ ankylosis in these patients.