Heterotopic Ossification: Basic-Science Principles and Clinical Correlates

Arthroscopic management of elbow stiffness

The elbow is particularly prone to stiffness. Loss of elbow motion is very limiting, and can be the result of trauma, primary osteoarthritis, heterotopic ossification and other conditions. Several exposures have been described for open elbow contracture release. Although a few decades ago elbow arthroscopy was considered only for diagnosis and removal of loose bodies, contemporary arthroscopic techniques allow successful management of the majority of conditions leading to elbow stiffness. Careful patient evaluation, use of advanced imaging studies, and acquisition of appropriate surgical skills are essential for the successful arthroscopic management of the stiff elbow. This expert opinion reviews some fundamentals of elbow stiffness as well as principles for the evaluation and arthroscopic management of the stiff elbow.

Three-dimensional printed polylactic acid scaffold integrated with BMP-2 laden hydrogel for precise bone regeneration

BACKGROUND

Critical bone defects remain challenges for clinicians, which cannot heal spontaneously and require medical intervention. Following the development of three-dimensional (3D) printing technology is widely used in bone tissue engineering for its outstanding customizability. The 3D printed scaffolds were usually accompanied with growth factors, such as bone morphometric protein 2 (BMP-2), whose effects have been widely investigated on bone regeneration. We previously fabricated and investigated the effect of a polylactic acid (PLA) cage/Biogel scaffold as a carrier of BMP-2. In this study, we furtherly investigated the effect of another shape of PLA cage/Biogel scaffold as a carrier of BMP-2 in a rat calvaria defect model and an ectopic ossification (EO) model.

METHOD

The PLA scaffold was printed with a basic commercial 3D printer, and the PLA scaffold was combined with gelatin and alginate-based Biogel and BMP-2 to induce bone regeneration. The experimental groups were divided into PLA scaffold, PLA scaffold with Biogel, PLA scaffold filled with BMP-2, and PLA scaffold with Biogel and BMP-2 and were tested both in vitro and in vivo. One-way ANOVA with Bonferroni post-hoc analysis was used to determine whether statistically significant difference exists between groups.

RESULT

The in vitro results showed the cage/Biogel scaffold released BMP-2 with an initial burst release and followed by a sustained slow-release pattern. The released BMP-2 maintained its osteoinductivity for at least 14 days. The in vivo results showed the cage/Biogel/BMP-2 group had the highest bone regeneration in the rat calvarial defect model and EO model. Especially, the bone regenerated more regularly in the EO model at the implanted sites, which indicated the cage/Biogel had an outstanding ability to control the shape of regenerated bone.

CONCLUSION

In conclusion, the 3D printed PLA cage/Biogel scaffold system was proved to be a proper carrier for BMP-2 that induced significant bone regeneration and induced bone formation following the designed shape.

The effect of traumatic brain injury on bone healing from a novel exosome centered perspective in a mice model

Background

In patients with traumatic brain injury (TBI) combined with long bone fracture, the fracture healing is always faster than that of patients with single fracture, which is characterized by more callus growth at the fracture site and even ectopic ossification. Exosomes are nanoscale membrane vesicles secreted by cells, which contain cell-specific proteins, miRNAs, and mRNAs.

Methods

In this study, we used exosomes as the entry point to explore the mechanism of brain trauma promoting fracture healing. We established a model of tibia fracture with TBI in mice to observe the callus growth and expression of osteogenic factors at the fracture site. Blood samples of model mice were further collected, exosomes in plasma were extracted by ultra-centrifugation method, and then identified and acted on osteoblasts cultured in vitro. The effects of exosomes on osteoblast differentiation at the cell, protein and gene levels were investigated by Western Blot and q-PCR, respectively. Furthermore, miRNA sequencing of exosomes was performed to identify a pattern of miRNAs that were present at increased or decreased levels.

Results

The results suggested that plasma exosomes after TBI had the ability to promote the proliferation and differentiation of osteoblasts, which might be due to the increased expression of osteoblast-related miRNA in exosomes. They were transmitted to the osteoblasts at the fracture site, so as to achieve the role of promoting osteogenic differentiation.

Conclusion

The TBI-derived exosomes may have potential applications for promoting fracture healing in future.

The Translational Potential of this Article

Plasma exosomes early after TBI have the ability to promote osteoblast proliferation and differentiation. The mechanism may be achieved by miRNA in exosomes. Plasma exosomes may be used as breakthrough clinical treatment for delayed or non-union fractures.

Osseous metaplasia of the endometrium: A multicenter retrospective study

OBJECTIVE

To describe clinical and demographic characteristics, ultrasound appearance, and hysteroscopic outcomes of patients with endometrial osseous metaplasia.

STUDY DESIGN

We conducted a multicenter retrospective study. We retrospectively reviewed the medical records of all consecutive patients who were referred for hysteroscopy at fourteen institutions in Venezuela, Spain, Morocco, India, Ukraine, Argentina, the United States, and Italy between 1994 and 2018. We identified and included all patients who had a diagnosis of osseous metaplasia at the pathologic report, and data were retrieved from the medical records.

RESULTS

Between January 1st, 1994, and December 31st, 2018, 63 patients out of a total of 419,673 women who underwent hysteroscopy had a diagnosis of osseous metaplasia (0.015%). Most patients were 31-40 years old (53.7%), were Caucasian or Hispanic (95.5%), and had at least one previous pregnancy (86.9%). Forty-one out of 63 patients (65.1%) had at least one miscarriage before the index hysteroscopy. Dysmenorrhea, abnormal uterine bleeding, and infertility were reported by 34.9%, 27.0%, and 23.8% of patients. 14.3% of women were asymptomatic. Preoperative transvaginal ultrasound was available and identified a hyperechoic area of variable size with posterior acoustic shadowing in all cases. Hysteroscopy was successful without complications in all 63 cases. Follow-up data were available in 30.2% of patients: 69.2% of patients were infertile, and 44.4% of them conceived and achieved a live birth; all other symptoms improved after hysteroscopic treatment in all patients.

CONCLUSIONS

Osseous metaplasia appears associated with multiple unspecific gynecologic symptoms without the predominant role of infertility, as previously suggested. Although endometrial osseous metaplasia is rare, gynecologists should consider this pathologic condition when the characteristic ultrasound appearance is detected, being hysteroscopic treatment effective.

The Gasotransmitter Hydrogen Sulfide (H2S) Prevents Pathologic Calcification (PC) in Cartilage

Pathologic calcification (PC) is a painful and disabling condition whereby calcium-containing crystals deposit in tissues that do not physiologically calcify: cartilage, tendons, muscle, vessels and skin. In cartilage, compression and inflammation triggered by PC leads to cartilage degradation typical of osteoarthritis (OA). The PC process is poorly understood and treatments able to target the underlying mechanisms of the disease are lacking. Here we show a crucial role of the gasotransmitter hydrogen sulfide (H₂S) and, in particular, of the H₂S-producing enzyme cystathionine γ-lyase (CSE), in regulating PC in cartilage. Cse deficiency (Cse KO mice) exacerbated calcification in both surgically-induced (menisectomy) and spontaneous (aging) murine models of cartilage PC, and augmented PC was closely associated with cartilage degradation (OA). On the contrary, Cse overexpression (Cse tg mice) protected from these features. In vitro, Cse KO chondrocytes showed increased calcification, potentially via enhanced alkaline phosphatase (Alpl) expression and activity and increased IL-6 production. The opposite results were obtained in Cse tg chondrocytes. In cartilage samples from patients with OA, CSE expression inversely correlated with the degree of tissue calcification and disease severity. Increased cartilage degradation in murine and human tissues lacking or expressing low CSE levels may be accounted for by dysregulated catabolism. We found higher levels of matrix-degrading metalloproteases Mmp-3 and -13 in Cse KO chondrocytes, whereas the opposite results were obtained in Cse tg cells. Finally, by high-throughput screening, we identified a novel small molecule CSE positive allosteric modulator (PAM), and demonstrated that it was able to increase cellular H₂S production, and decrease murine and human chondrocyte calcification and IL-6 secretion. Together, these data implicate impaired CSE-dependent H₂S production by chondrocytes in the etiology of cartilage PC and worsening of secondary outcomes (OA). In this context, enhancing CSE expression and/or activity in chondrocytes could represent a potential strategy to inhibit PC.

NGF-TrkA signaling dictates neural ingrowth and aberrant osteochondral differentiation after soft tissue trauma

Pain is a central feature of soft tissue trauma, which under certain contexts, results in aberrant osteochondral differentiation of tissue-specific stem cells. Here, the role of sensory nerve fibers in this abnormal cell fate decision is investigated using a severe extremity injury model in mice. Soft tissue trauma results in NGF (Nerve growth factor) expression, particularly within perivascular cell types. Consequently, NGF-responsive axonal invasion occurs which precedes osteocartilaginous differentiation. Surgical denervation impedes axonal ingrowth, with significant delays in cartilage and bone formation. Likewise, either deletion of Ngf or two complementary methods to inhibit its receptor TrkA (Tropomyosin receptor kinase A) lead to similar delays in axonal invasion and osteochondral differentiation. Mechanistically, single-cell sequencing suggests a shift from TGFβ to FGF signaling activation among pre-chondrogenic cells after denervation. Finally, analysis of human pathologic specimens and databases confirms the relevance of NGF-TrkA signaling in human disease. In sum, NGF-mediated TrkA-expressing axonal ingrowth drives abnormal osteochondral differentiation after soft tissue trauma. NGF-TrkA signaling inhibition may have dual therapeutic use in soft tissue trauma, both as an analgesic and negative regulator of aberrant stem cell differentiation.

Heterotopic Ossification Negatively Influences Range of Motion After Revision Total Knee Arthroplasty

BACKGROUND

The incidence of heterotopic ossification (HO) after total knee arthroplasty (TKA) varies and is of unclear clinical significance. This study aimed to identify the incidence of HO in patients undergoing revision TKA for either stiffness or aseptic loosening/instability and determine if the presence of HO is associated with inferior absolute range of motion (ROM) and ROM gains.

METHODS

Eighty-seven patients were prospectively enrolled and separated into 2 cohorts to evaluate ROM after revision TKA (2017-2019). Group 1 (N = 40) patients were revised for stiffness, while group 2 (N = 47) patients were revised for either aseptic loosening or instability. Goniometer-measured ROM values were obtained preoperatively and at 6 weeks, 6 months, and 1 year postoperatively. Statistical analysis included a Fisher's exact test to assess for an association between preoperative HO and final ROM at 1 year after revision TKA.

RESULTS

HO was identified on preoperative radiographs in 17 patients (20%). There was a significantly higher rate of preoperative HO in patients revised for stiffness compared to patients revised for instability or loosening (30% vs 11%; P = .03). Five cases of HO qualitatively identified as most clinically severe were associated with lower ROM at each time point compared to the remainder of HO cases in this study cohort (P < .02).

CONCLUSION

The presence of HO is greater in patients undergoing revision TKA for stiffness. Additionally, HO severity appears to have a major effect on preoperative and postoperative ROM trajectory. This information should help guide patient expectations and highlight the need for a comprehensive, standardized classification system for HO.

Extracorporeal shock wave therapy to treat neurogenic heterotopic ossification in a patient with spinal cord injury: A case report

Objective: To evaluate the efficacy and safety of treatment for neurogenic heterotopic ossification (NHO) using extracorporeal shock wave therapy (ESWT) in persons with spinal cord injury (SCI).Design: Single case report.Setting: Department of Physical Medicine and Rehabilitation, Veterans Health Service Medical Center.Participants: A 55-year-old male with cervical SCI, who developed painful NHO around the right hip joint.Interventions: Ultrasound-guided ESWT that used 4,000 shocks at the rate of 3 Hz and the energy flux density between 0.056 and 0.068 mJ/mm² was applied to the NHO region a total of 7 times, weekly.Outcome Measures: We assessed the treatment outcomes using a visual analog scale (VAS) score, wheelchair sitting time and size of NHO.Result: After 7 weeks of ESWT treatment, his pain reduced from a VAS score of 7-8 to 3 and his wheelchair sitting time increased. However, there was no significant change of size of NHO.Conclusion: The application of ESWT could be a possible alternative to other treatments for NHO in persons with SCI.Clinical Trial Registry Number: 2019-03-003.

A Rare Case of Extremely Severe Heterotopic Ossification after Primary Total Hip Arthroplasty due to Persistent Mild Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) caused by coagulase-negative staphylococci (CNS) can be a mild, persisting infection. Although heterotopic ossification (HO) is common following total hip arthroplasty (THA), the etiology of severe HO remains unclear. Herein, we describe a rare case of extremely severe HO after a PJI associated with a Staphylococcus caprae infection in a 78-year-old male patient. The patient had poorly controlled diabetes mellitus with no diabetic complications. The patient had no previous history of hip surgery, hip injury, or systemic bacterial infection. Immediately after the initial THA, he developed intermittent low-grade fever (37°C), which persisted for 3 months; consequently, he also reported mild hip pain during walking. He experienced a gradual decrease in hip range of motion within 5 years after the surgery, with progressive gait impairment. Two revision surgeries were required for the successful treatment of this difficult case. The patient's hip function improved, and the PJI was controlled following the second revision surgery. Based on the clinical course, CNS-caused PJI may lead to severe HO. This possibility warrants verification from an accumulated number of cases.

Low-Dose Aspirin Administered for Venous Thromboembolism Prophylaxis Reduces the Incidence of Heterotopic Ossification in Total Joint Arthroplasty

BACKGROUND

Heterotopic ossification (HO) is a common complication following total joint arthroplasty (TJA). However, the pathophysiology of HO is not entirely understood. Inflammation may play a significant role in the pathogenesis of HO as nonsteroidal anti-inflammatory drugs are effective in the prevention of HO. The purpose of this study is to examine if aspirin (ASA), when used as venous thromboembolism (VTE) prophylaxis, influenced the rate of HO formation following TJA.

METHODS

We queried our longitudinally maintained database to identify all patients who underwent primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) for osteoarthritis between January 2016 and June 2018 with at least 3-month radiographic follow-up. In total, 1238 THAs and 1051 TKAs were included for analysis. Radiographs were reviewed and HO formation graded according to the Brooker classification. Patient demographic and VTE prophylaxis data were collected and reviewed for accuracy. Univariate and multivariate analysis was performed to evaluate the effect of ASA on HO formation.

RESULTS

The overall rate of HO was 37.5% after THA and 17.4% after TKA. Patients receiving ASA were less likely to develop HO after THA (34.8% vs 45.5%; P < .001), as well as HO after TKA (13.4% vs 18.4%; P = .047) compared to patients receiving non-ASA VTE prophylaxis. The rate of HO formation trended to be lower, albeit not statistically significantly, in patients receiving low-dose ASA (81 mg) vs high-dose ASA (325 mg).

CONCLUSION

Patients undergoing primary TJA receiving ASA for VTE prophylaxis were less likely to develop HO compared to patients who were administered non-ASA VTE prophylaxis.

High Frequency Spectral Ultrasound Imaging Detects Early Heterotopic Ossification in Rodents

Heterotopic ossification (HO) is a devastating condition in which ectopic bone forms inappropriately in soft tissues following traumatic injuries and orthopedic surgeries as a result of aberrant mesenchymal progenitor cell (MPC) differentiation. HO leads to chronic pain, decreased range of motion, and an overall decrease in quality of life. While several treatments have shown promise in animal models, all must be given during early stages of formation. Methods for early determination of whether and where endochondral ossification/soft tissue mineralization (HO anlagen) develop are lacking. At-risk patients are not identified sufficiently early in the process of MPC differentiation and soft tissue endochondral ossification for potential treatments to be effective. Hence, a critical need exists to develop technologies capable of detecting HO anlagen soon after trauma, when treatments are most effective. In this study, we investigate high frequency spectral ultrasound imaging (SUSI) as a noninvasive strategy to identify HO anlagen at early time points after injury. We show that by determining quantitative parameters based on tissue organization and structure, SUSI identifies HO anlagen as early as 1-week postinjury in a mouse model of burn/tenotomy and 3 days postinjury in a rat model of blast/amputation. We analyze single cell RNA sequencing profiles of the MPCs responsible for HO formation and show that the early tissue changes detected by SUSI match chondrogenic and osteogenic gene expression in this population. SUSI identifies sites of soft tissue endochondral ossification at early stages of HO formation so that effective intervention can be targeted when and where it is needed following trauma-induced injury. Furthermore, we characterize the chondrogenic to osteogenic transition that occurs in the MPCs during HO formation and correlate gene expression to SUSI detection of the HO anlagen.

Excision of Heterotopic Ossification around the Hip: Arthroscopic and Open Techniques

Heterotopic ossification (HO) can occur as a complication of various pathologies affecting the hip including trauma, tendon avulsions, chronic injury, spinal cord injury, and soft-tissue disruption caused by surgery. When HO is present alongside intra-articular hip pathology such as femoroacetabular impingement syndrome (FAIS) or labral pathology, consideration should be made to combine the surgical excision of the HO with the FAIS decompression or labral repair if the location and size of the HO is appropriate for arthroscopic excision. Often times, the HO is located in such a position that any central compartment work can be completed before turning to the HO excision. If an open approach is required, the modified Gibson approach can be used for lateral hip access, whereas the Smith-Petersen approach provides anterior hip access. In this Technical Note we discuss arthroscopic techniques for excision of HO in the setting of concomitant FAIS, with discussion of when HO excision occurs in relation to cam decompression and labral repair, and mention tips on how to approach HO excision through an open approach.

Successful Arthroscopic Fixation of a Posterior Wall Acetabular Fracture Nonunion on a Patient With Femoroacetabular Impingement: A Case Report

CASE

This report presents the results of a hip arthroscopic technique that was used to treat an unusual posterior wall acetabular fracture nonunion. A 30-year-old man presented with 1 year of persistent left-sided buttock and groin pain with associated feeling of instability when climbing stairs. Magnetic resonance imaging demonstrated a small left acetabular posterior wall fracture nonunion. We describe outpatient treatment with reduction and cannulated screw fixation using arthroscopic techniques that permitted immediate partial weight bearing and achieved excellent outcomes at 1 year.

CONCLUSION

Arthroscopic fixation of an acetabular posterior wall fracture nonunion may be a feasible treatment option in select cases.

Heterotopic ossification in the post cruciate ligament of the knee: a case report and literature review

Background

Heterotopic ossification (HO) is noted most frequently in periarticular muscles and has not yet been reported in the cruciate ligaments of the knee. We present a rare case of symptomatic ossification of the posterior cruciate ligament (PCL).

Case presentation

A 59-year-old woman had a 2-year history of knee pain that was getting worse during knee motion and had restricted knee motion for 1 year. X-rays could not show the lesion clearly. Multi-planar computed tomography demonstrated ossification within the PCL with mild osteoarthritic changes and excluded any other intra-articular pathology. The patient underwent arthroscopic debridement and then experienced immediate relief of pain and complete recovery of range of motion.

Conclusion

This is the first report of HO in the PCL as a possible cause of knee pain and restricted knee motion. On the basis of literature review, this case elaborates the difference between HO and calcification in the ligaments, the related factors inducing HO and the undefined pathogenesis, and favorable prognosis after adequate treatment.

Spontaneous heterotopic mesenteric ossification around the pancreas causing duodenal stenosis: A case report with literature review

INTRODUCTION AND IMPORTANCE

Heterotopic mesenteric ossification (HMO) is a rare condition that can be hereditary or nonhereditary. It can lead to small bowel obstruction, which may require corrective surgery. Most affected patients have a history of abdominal surgery or trauma. Spontaneously occurring HMO is even rarer, with only 7 cases reported till date. There has been no previous report of spontaneous peripancreatic HMO.

CASE PRESENTATION

A 60-year-old man presented with complaints of recurrent nausea and vomiting for 2 months. Esophagogastroduodenoscopy revealed luminal stenosis and edematous changes involving the second and third parts of the duodenum but not its complete obstruction. Abdominopelvic computed tomography showed faintly enhanced thickening of the involved duodenal walls along with mild dilatation of the common bile duct. Considering the possibility of periampullary cancer, we performed a pylorus-preserving pancreaticoduodenectomy. Histopathological examination confirmed the diagnosis of HMO with extensive fibrosis involving the peripancreatic soft tissue.

CLINICAL DISCUSSION

The peripancreatic HMO with severe fibrosis can occur duodenal stenosis, and it is mimicking periampullary cancer. However, the preoperative diagnosis of spontaneous HMO is difficult, and a diagnosis confirmed after surgery.

CONCLUSION

Herein, we described our experience of managing a rare case of duodenal stenosis due to spontaneous HMO involving peripancreatic tissue.

Risk Factors for Elbow Joint Contracture After Surgical Repair of Traumatic Elbow Fracture

PURPOSE

The ability to predict contracture development after elbow fracture would benefit patients and physicians. This study aimed to identify factors associated with the development of posttraumatic elbow joint contracture.

METHODS

A retrospective review of elbow fractures (AO/Orthopaedic Trauma Association [OTA] type 13 and 21) treated at one institution between 2011 and 2015 was performed. Data collected included demographics, injury information, treatment, and postoperative elbow range of motion (ROM). Multivariate logistic regression analyses were performed to identify factors associated with contracture development. Notable contracture was defined as an arc of motion less than 100° flexion/extension, which has been associated with reduced ability to perform activities of daily living.

RESULTS

A total of 278 patients at least 1 8 years of age underwent surgical repair of an elbow fracture or fracture-dislocation during the study period and had at least 6 months of postoperative follow-up. Forty-two (15.1%) developed a clinically notable elbow contracture, of whom 29 (69.0%) developed heterotopic ossification (HO). Multivariate analysis of preoperative variables demonstrated that AO/OTA 13-C fracture classification (odds ratio [OR], 13.7, P = 0.025), multiple noncontiguous fractures (OR, 3.7, P = 0.010), and ulnohumeral dislocation at the time of injury (OR, 4.9, P = 0.005) were independently associated with contracture development. At 6 weeks postoperatively, an arc of elbow ROM less than 50° flexion/extension (OR, 23.0, P < 0.0005) and the presence of HO on radiographs (OR, 6.7, P < 0.0005) were found to be independent risk factors for significant elbow stiffness.

DISCUSSION

Ulnohumeral dislocation, multiple noncontiguous fractures, AO/OTA 13-C fracture classification, limited elbow ROM at 6 weeks postoperatively, and the presence of radiographic HO at 6 weeks postoperatively are associated with contracture development after surgical elbow fracture repair. Patients with these risk factors should receive aggressive physical therapy and be counseled as to the possible development of a contracture requiring surgical intervention.

A review of the biomarkers and in vivo models for the diagnosis and treatment of heterotopic ossification following blast and trauma-induced injuries

Heterotopic ossification (HO) is the process of de novo bone formation in non-osseous tissues. HO can occur following trauma and burns and over 60% of military personnel with blast-associated amputations develop HO. This rate is far higher than in other trauma-induced HO development. This suggests that the blast effect itself is a major contributing factor, but the pathway triggering HO following blast injury specifically is not yet fully identified. Also, because of the difficulty of studying the disease using clinical data, the only sources remain the relevant in vivo models. The aim of this paper is first to review the key biomarkers and signalling pathways identified in trauma and blast induced HO in order to summarize the molecular mechanisms underlying HO development, and second to review the blast injury in vivo models developed. The literature derived from trauma-induced HO suggests that inflammatory cytokines play a key role directing different progenitor cells to transform into an osteogenic class contributing to the development of the disease. This highlights the importance of identifying the downstream biomarkers under specific signalling pathways which might trigger similar stimuli in blast to those of trauma induced formation of ectopic bone in the tissues surrounding the site of the injury. The lack of information in the literature regarding the exact biomarkers leading to blast associated HO is hampering the design of specific therapeutics. The majority of existing blast injury in vivo models do not fully replicate the combat scenario in terms of blast, fracture and amputation; these three usually happen in one insult. Hence, this paper highlights the need to replicate the full effect of the blast in preclinical models to better understand the mechanism of blast induced HO development and to enable the design of a specific therapeutic to supress the formation of ectopic bone.

BMPR1B gene in brachydactyly type 2-A family with de novo R486W mutation and a disease phenotype

Background

Brachydactylies are a group of inherited conditions, characterized mainly by the presence of shortened fingers and toes. Based on the patients’ phenotypes, brachydactylies have been subdivided into 10 subtypes. In this study, we have identified a family with two members affected by brachydactyly type A2 (BDA2). BDA2 is caused by mutations in three genes: BMPR1B, BMP2 or GDF5. So far only two studies have reported the BDA2 cases caused by mutations in the BMPR1B gene.

Methods

We employed next‐generation sequencing to identify mutations in culpable genes.

Results and Conclusion

In this paper, we report a case of BDA2 resulting from the presence of a heterozygous c.1456C>T, p.Arg486Trp variant in BMPR1B, which was previously associated with BDA2. The next generation sequencing analysis of the patients’ family revealed that the mutation occurred de novo in the proband and was transmitted to his 26‐month‐old son. Although the same variant was confirmed in both patients, their phenotypes were different with more severe manifestation of the disease in the adult.

Early diagnosis of heterotopic ossification among patients admitted to a neurological Post-Intensive Care Rehabilitation Unit

BACKGROUND

Heterotopic ossification (HO) is defined as the formation of endochondral bone within soft tissue. Non-genetic forms, mainly corresponding to a consequence of bone, brain or spinal cord injury, are the most common. HO leads to important functional limitations and alteration of quality of life. To our knowledge, the time between brain, bone, or spinal cord injury and clinical suspicion of HO has never been studied. By admitting patients with severe neurological disorders, we hypothesized that the prevalence of HO in neurological post-intensive care rehabilitation units (PICRU) might be significant as these patients have recognized risk factors for HO.

AIM

This study aimed to investigate HO among patients admitted to a neurological PICRU with two objectives: 1) to describe the prevalence of HO in PICRU; 2) to assess the time between neurological disorder, clinical suspicion of HO and radiological diagnosis.

DESIGN

A monocentric retrospective cohort study.

SETTING

PICRU in our public university teaching hospital. This inpatient referral department is specifically dedicated to the early discharge from Intensive Care Units (ICU) of patients with severe neurological impairment who need rehabilitation.

POPULATION

We study all patients admitted between April 2016 and January 2019. One hundred twenty-five subjects were admitted for a rehabilitation program after neuro-trauma or stroke. We included all first-time stays in PICRU lasting 7 days or longer.

METHODS

Retrospective data extraction using administrative data from an electronic patient management program was done to select eligible subjects. Included subjects were then identified by a retrospective review of electronic inpatient medical records after patient discharge. Data of interest were collected from these same medical records.

RESULTS

Forty-four HO were diagnosed in 24 subjects (24/125; 19%), with a median number of 2 [1; 2] HO per subject. Neurological trauma was the main reason for admission to ICU (89/125; 71%) and half of patients had a traumatic brain injury (TBI) (67/125; 54%). The diagnosis of HO was made in PICRU in 75% of cases. Clinical suspicion of HO (autonomic dysfunction, local inflammatory signs, pain, or reduced joint range of motion) was made 6 [5; 7] weeks after admission to ICU. Radiological confirmation of clinical suspicion or fortuitous diagnosis by imaging (50% of the cases) occurred 8 [7; 12] weeks after admission to ICU. The median time of clinical suspicion or radiological diagnosis was 1 week after admission to PICRU.

CONCLUSIONS

HO is a sub-acute complication which develops in patients admitted to ICU for severe central nervous system disorders as clinical suspicion or radiological confirmation of diagnosis was made within the first week after admission in neurological PICRU (i.e. 6 to 8 weeks after ICU admission).

CLINICAL REHABILITATION IMPACT

As treatment for HO may at least partially improves rehabilitation and quality of life, we recommend a systematic screening in PICRU patients for HO by clinical examination supplemented by imaging in case of suspicion.

Musculoskeletal morbidity following spinal cord injury: A longitudinal cohort study of privately-insured beneficiaries

BACKGROUND

People living with spinal cord injuries (SCIs) experience motor, sensory and autonomic impairments that cause musculoskeletal disorders following the injury and that progress throughout lifetime. The range and severity of issues are largely dependent on level and completeness of the injury and preserved function.

OBJECTIVE

High risk of developing musculoskeletal morbidities among individuals after sustaining a traumatic SCI is well known in the clinical setting, however, there is a severe lack of evidence in literature. The objective of this study was to compare the incidence of and adjusted hazards for musculoskeletal morbidities among adults with and without SCIs.

METHODS

Privately-insured beneficiaries were included if they had an ICD-9-CM diagnostic code for SCI (n = 9081). Adults without SCI were also included (n = 1,474,232). Incidence estimates of common musculoskeletal morbidities (e.g., osteoporosis, sarcopenia, osteoarthritis, fractures, etc.) were compared at 5-years of enrollment. Survival models were used to quantify unadjusted and adjusted hazard ratios for incident musculoskeletal morbidities.

RESULTS

Adults living with traumatic SCIs had a higher incidence of any musculoskeletal morbidities (82.4% vs. 47.5%) as compared to adults without SCI, and differences were to a clinically meaningful extent. Survival models demonstrated that adults with SCI had a greater fully-adjusted hazard for any musculoskeletal morbidity (Hazard Ratio [HR]: 2.41; 95%CI: 2.30, 2.52), and all musculoskeletal disorders, and ranged from HR: 1.26 (1.14, 1.39) for rheumatoid arthritis to HR: 7.02 (6.58, 7.49) for pathologic fracture.

CONCLUSIONS

Adults with SCIs have a significantly higher incidence of and risk for common musculoskeletal morbidities, as compared to adults without SCIs. Efforts are needed to facilitate the development of improved clinical screening algorithms and early interventions to reduce risk of musculoskeletal disease onset/progression in this higher risk population.

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 in primary total hip arthroplasty using the posterolateral compared to the direct lateral approach

PURPOSE

Total hip arthroplasty (THA) is a successful procedure. However, in time, heterotopic ossification (HO) can form due to, amongst others, soft tissue damage. This can lead to pain and impairment. This study compares the formations of HO between patients who underwent either THA with the posterolateral approach (PA) or with the direct lateral approach (DLA). Our hypothesis is that patients who underwent THA with a PA form less HO compared to THA patients who underwent DLA.

METHODS

In this prospective cohort study, 296 consecutive patients were included who underwent THA. A total of 127 patients underwent THA with the PA and 169 with the DLA. This was dependent on the surgeon's preference and experience. More than 95% of patients had primary osteoarthritis as the primary diagnosis. Clinical outcomes were scored using the Numeric Rating Scale (NRS) and Harris Hip Score (HHS), radiological HO were scored using the Brooker classification. Follow-up was performed at 1 and 6 years postoperatively.

RESULTS

Two hundred and fifty-eight patients (87%) completed the 6-year follow-up. HO formation occurred more in patients who underwent DLA, compared to PA (43(30%) vs. 21(18%), p = 0.024) after 6 years. However, the presence of severe HO (Brooker 3-4) was equal between the DLA and PA (7 vs. 5, p = 0.551). After 6 years the HHS and NRS for patient satisfaction were statistically significant higher after the PA (95.2 and 8.9, respectively) compared to the DLA (91.6 and 8.5, respectively) (p < 0.001 and p = 0.003, respectively). The NRS for load pain was statistically significant lower in the PA group (0.5) compared to the DLA group (1.2) (p = 0.004). The NRS for rest pain was equal: 0.3 in the PA group and 0.5 in the DLA group.

CONCLUSION

THA with the PA causes less HO formation than the DLA.

TRIAL REGISTRATION

Registrated as HipVit trial, NL 32832.100.10, R-10.17D/HIPVIT 1. Central Commission Human-Related research (CCMO) Registry.

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.

Neurological heterotopic ossification: novel mechanisms, prognostic biomarkers and prophylactic therapies

Neurological heterotopic ossification (NHO) is a debilitating condition where bone forms in soft tissue, such as muscle surrounding the hip and knee, following an injury to the brain or spinal cord. This abnormal formation of bone can result in nerve impingement, pain, contractures and impaired movement. Patients are often diagnosed with NHO after the bone tissue has completely mineralised, leaving invasive surgical resection the only remaining treatment option. Surgical resection of NHO creates potential for added complications, particularly in patients with concomitant injury to the central nervous system (CNS). Although recent work has begun to shed light on the physiological mechanisms involved in NHO, there remains a significant knowledge gap related to the prognostic biomarkers and prophylactic treatments which are necessary to prevent NHO and optimise patient outcomes. This article reviews the current understanding pertaining to NHO epidemiology, pathobiology, biomarkers and treatment options. In particular, we focus on how concomitant CNS injury may drive ectopic bone formation and discuss considerations for treating polytrauma patients with NHO. We conclude that understanding of the pathogenesis of NHO is rapidly advancing, and as such, there is the strong potential for future research to unearth methods capable of identifying patients likely to develop NHO, and targeted treatments to prevent its manifestation.

Diagnosis of Klippel-Trenaunay syndrome and extensive heterotopic ossification in a patient with a femoral fracture: a case report and literature review

Background

Klippel-Trenaunay syndrome (KTS) is a rare complex vessel malformation syndrome characterized by venous varicosities, capillary malformations, and limb hypertrophy. However, extensive heterotopic ossification (HO) secondary to this syndrome is extremely rare.

Case presentation

We report the case of a patient with previously undiagnosed KTS and extensive HO who presented with a femoral fracture secondary to a motor vehicle accident. Extensive ossification, which leads to compulsive contracture deformity and dysfunction of the leg, was distributed on the flexor muscle side, as revealed by the radiograph. The diagnosis was finally established by combining imaging and histological analysis with classical clinical symptoms. Amputation was performed at the fracture site proximal to the infected necrotic foci. Open management of the fracture was challenging owning to the pervasive ossification and tendency for excessive bleeding. Gene sequencing analysis showed homozygous mutation of FoxO1 gene.

Conclusions

Definitive diagnosis of a combination of KTS and extensive HO requires detailed imaging analysis and pathologic evidence. Mutation of the FoxO1 gene, which regulates bone formation by resistance to oxidative stress in osteoblasts, is a potential factor in the microenvironment of malformed vessels caused by KTS.

Phylogeny and chemistry of biological mineral transport

Three physiologically mineralizing tissues - teeth, cartilage and bone - have critical common elements and important evolutionary relationships. Phylogenetically the most ancient densely mineralized tissue is teeth. In jawless fishes without skeletons, tooth formation included epithelial transport of phosphates, a process echoed later in bone physiology. Cartilage and mineralized cartilage are skeletal elements separate from bone, but with metabolic features common to bone. Cartilage mineralization is coordinated with high expression of tissue nonspecific alkaline phosphatase and PHOSPHO1 to harvest available phosphate esters and support mineralization of collagen secreted locally. Mineralization in true bone results from stochastic nucleation of hydroxyapatite crystals within the cross-linked collagen fibrils. Mineral accumulation in dense collagen is, at least in major part, mediated by amorphous aggregates - often called Posner clusters - of calcium and phosphate that are small enough to diffuse into collagen fibrils. Mineral accumulation in membrane vesicles is widely suggested, but does not correlate with a definitive stage of mineralization. Conversely mineral deposition at non-physiologic sites where calcium and phosphate are adequate has been shown to be regulated in large part by pyrophosphate. All of these elements are present in vertebrate bone metabolism. A key biological element of bone formation is an epithelial-like cellular organization which allows control of phosphate, calcium and pH during mineralization.

Enhanced Spinal Therapy: Extracorporeal Shock Wave Therapy for the Spine

Extracorporeal shock wave therapy (ESWT) is a non-invasive therapeutic method used for pain management and muscle strength improvement through the use of shock waves. In vitro studies have demonstrated that shockwave therapy induces fluctuation in redox reaction regulation and increases in Mitogen-Activated Protein Kinase (MAPK) signal transduction pathways, stimulating increased gene expression in the nucleus. ESWT has also been shown to upregulate angiogenesis and growth factors through activation of endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF). The use of ESWT in the treatment of various musculoskeletal disorders was widely adopted throughout Europe, South America, and Asia before being introduced in the United States in 2000. Within the past 20 years, the clinical application of ESWT in the treatment of musculoskeletal and bone disorders has grown. This paper provides a comprehensive narrative review of applications and outcomes of ESWT in clinical spinal pathology and assesses reported efficacy as it relates to the pathology. A review of the literature yielded studies describing the use of ESWT in degenerative osteoporotic neuro-spinal pathology, heterotopic ossification due to spinal cord injury, cervical spondylosis, scoliosis, sacroiliitis, and coccydynia. The efficacy of ESWT as an adjunct treatment in patients with spinal cord pathologies varied with the specific pathology, however, all pathologies discussed in this review provided evidence of potential benefits with minimal adverse effects. While the use of ESWT for pain management has widely been established, further literature should aim to identify the long-term benefits of ESWT.

Effect of heterotopic ossification after bryan-cervical disc arthroplasty on adjacent level range of motion: A finite element study

BACKGROUND

Quantitative bone re-modelling theories suggest that bones adapt to mechanical loading conditions. Follow-up studies have shown that total disc replacement (TDR) modifies stress patterns in the bones, leading to heterotopic ossification (HO). Although there are a few studies on HO using finite element models (FEM), its effect on the adjacent levels and change in range of motion (ROM) have not been adequately investigated. This study interfaces the HO using bone re-modelling algorithm with a finite element solution and investigates the subsequent changes in segmental ROM.

METHODS

A FEM of the human cervical spine (C3-C7) was developed for this study, with material properties obtained from literature. The motion of the segments in the sagittal, frontal and transverse planes under combined loading conditions of 1 Nm moment and 73.6 N compression were validated against experimental corridors. The natural disc between the C5-C6 segment was replaced with the Bryan artificial cervical disc, and changes in sagittal ROM were compared before and after HO. The process of HO was simulated using a bone remodelling algorithm using strain energy density (SED) as the mechanical stimuli.

RESULTS AND CONCLUSION

Our study demonstrates the feasibility of using SED calculations from the flexion-extension loading conditions for prediction of HO after ADR. The current findings suggest that the nature of trabecular stresses, and the subsequent rate and location of HO formation could differ based on the geometric design and nature of constraint for different artificial discs. The Bryan disc significantly reduced ROM at the implanted level in flexion. However, in extension, ROM increased at the implanted level and decreased slightly at the adjacent levels. After HO, ROM drastically reduced at the implanted level in both extension and flexion, and showed a minor increase in the adjacent levels, indicating that biomechanical behavior of high-grade HO is similar to a fused segment, thereby reducing the intended and initial motion preservation.

A 2-Week Course of Naproxen for Heterotopic Ossification Prophylaxis Is Effective Following Hip Arthroscopy for Femoroacetabular Impingement

Purpose

To evaluate the effectiveness of 2 weeks of naproxen prophylaxis for heterotopic ossification (HO) after primary hip arthroscopy for femoroacetabular impingement (FAI).

Methods

All consecutive hip arthroscopy cases by a single surgeon from January 1, 2015, to December 31, 2016, were retrospectively reviewed. Cases were included if they met the following criteria: (1) Primary hip arthroscopy, including femoral neck osteoplasty, for FAI; (2) naproxen prophylaxis for 2 weeks’ duration; and (3) radiographic follow-up at a minimum of 3 months postoperatively. Radiographic imaging for each patient was evaluated for the presence of HO, and independent radiology reports were used to confirm patients with HO. Maximal size of HO was measured and classified according to the Brooker criteria. Demographic and operative variables of the patients included in this study who received naproxen prophylaxis for 2 weeks were formally compared with a cohort of patients who received naproxen prophylaxis for 3 weeks in a previous randomized controlled trial.

Results

A total of 185 patients who received naproxen prophylaxis for 2 weeks were included in the study, 5 of whom developed HO (3%). A total of 48 patients who received naproxen prophylaxis for 3 weeks were included for comparison, 2 of whom developed HO (4%). There was no significant difference in the rate of HO formation between 2 weeks and 3 weeks of naproxen prophylaxis (P = .597). All 7 cases of HO were classified as Brooker class 1.

Conclusions

The observed rate of postoperative heterotopic ossification after 2 weeks of naproxen prophylaxis in this study was equivalent to that observed after 3 weeks’ prophylaxis in a previously published study. Two weeks of naproxen prophylaxis may be a sufficient treatment course for the prevention of heterotopic ossification after primary hip arthroscopy for FAI.

Level of Evidence

Level III – Retrospective Comparative Study.

Investigation into Possible Association of Oxandrolone and Heterotopic Ossification Following Burn Injury

Oxandrolone, a testosterone analog, is used to counteract the catabolic effects of burn injury. Recent animal studies suggest a possible hormonal association with heterotopic ossification (HO) development postburn. This work examines oxandrolone administration and HO development by exploring historical clinical data bridging the introduction of oxandrolone into clinical practice. Additionally, we examine associations between oxandrolone administration and HO in a standardized mouse model of burn/trauma-related HO. Acutely burned adults admitted between 2000 and 2014, survived through discharge, and had a HO risk factor of 7 or higher were selected for analysis from a single burn center. Oxandrolone administration, clinical and demographic data, and elbow HO were recorded and were analyzed with logistic regression. Associations of oxandrolone with HO were examined in a mouse model. Mice were administered oxandrolone or vehicle control following burn/tenotomy to examine any potential effect of oxandrolone on HO and were analyzed by Student's t test. Subjects who received oxandrolone had a higher incidence of elbow HO than those that did not receive oxandrolone. However, when controlling for oxandrolone administration, oxandrolone duration, postburn day oxandrolone initiation, HO risk score category, age, sex, race, burn size, and year of injury, there was no significant difference between rates of elbow HO between the two populations. In agreement with the review, in the mouse model, while there was a trend toward the oxandrolone group developing a greater volume of HO, this did not reach statistical significance.

Fibrodysplasia ossificans progressiva: current concepts from bench to bedside

Heterotopic ossification (HO) is a disorder characterised by the formation of ectopic bone in soft tissue. Acquired HO typically occurs in response to trauma and is relatively common, yet its aetiology remains poorly understood. Genetic forms, by contrast, are very rare, but provide insights into the mechanisms of HO pathobiology. Fibrodysplasia ossificans progressiva (FOP) is the most debilitating form of HO. All patients reported to date carry heterozygous gain-of-function mutations in the gene encoding activin A receptor type I (ACVR1). These mutations cause dysregulated bone morphogenetic protein (BMP) signalling, leading to HO at extraskeletal sites including, but not limited to, muscles, ligaments, tendons and fascia. Ever since the identification of the causative gene, developing a cure for FOP has been a focus of investigation, and studies have decoded the pathophysiology at the molecular and cellular levels, and explored novel management strategies. Based on the established role of BMP signalling throughout HO in FOP, therapeutic modalities that target multiple levels of the signalling cascade have been designed, and some drugs have entered clinical trials, holding out hope of a cure. A potential role of other signalling pathways that could influence the dysregulated BMP signalling and present alternative therapeutic targets remains a matter of debate. Here, we review the recent FOP literature, including pathophysiology, clinical aspects, animal models and current management strategies. We also consider how this research can inform our understanding of other types of HO and highlight some of the remaining knowledge gaps.

Summary: Fibrodysplasia ossificans progressiva is a rare disease characterised by progressive heterotopic bone formation. Here, we present a comprehensive summary of the recent literature on this debilitating condition and discuss approaches to solving this clinical puzzle.

Open elbow arthrolysis for post-traumatic elbow stiffness: an update

Post-traumatic elbow stiffness is a disabling condition that remains challenging for upper limb surgeons. Open elbow arthrolysis is commonly used for the treatment of stiff elbow when conservative therapy has failed. Multiple questions commonly arise from surgeons who deal with this disease. These include whether the patient has post-traumatic stiff elbow, how to evaluate the problem, when surgery is appropriate, how to perform an excellent arthrolysis, what the optimal postoperative rehabilitation is, and how to prevent or reduce the incidence of complications. Following these questions, this review provides an update and overview of post-traumatic elbow stiffness with respect to the diagnosis, preoperative evaluation, arthrolysis strategies, postoperative rehabilitation, and prevention of complications, aiming to provide a complete diagnosis and treatment path. Cite this article: Bone Joint Open 2020;1-9:576-584.

Radiotherapy for the prophylaxis of heterotopic ossification after total hip arthroplasty: A systematic review and meta-analysis of randomized controlled trails

Heterotopic ossification (HO) refers to the formation of lamellar bone in soft tissues and is a significant complication after total hip arthroplasty (THA). Radiotherapy has been proven as an effective prophylaxis especially for those patients with high risk of HO after THA. However the dose, timing, and frequency of radiation have yet to be determined. To compare HO progressions with different radiotherapy strategies and explore an optimal radiation option. We systematically searched PubMed, Embase, and Cochrane Library for randomized controlled trails (through December 1, 2019; no language restrictions) collecting patients who accepted prophylaxis radiation for whom HO progression outcomes were reported. Of 87 identified studies, 10 randomized controlled trails including 1203 patients and 1268 hips were taken to this analysis. Compared with the low biologically effective radiation dose group (biologically effective dose [BED] < 20 Gy), the medium biologically effective radiation dose group (20 Gy ≤ BED ≤ 24 Gy) had statistically significant difference on the prophylaxis of HO (p = 0.003). But for overall incidence of HO, there was no statistically significant difference between low BED group and high BED group (BED > 24, p = 0.21). There was statistically significant reduction in the prophylaxis of HO progression with multiple fractions as opposed to single fraction radiotherapy (p = 0.04). Hips with preoperative radiation were no more likely to observe HO progression than those with postoperative radiotherapy (p = 0.43). Radiotherapy with medium dose (20 Gy ≤ BED ≤ 24 Gy) after THA is an effective dose for preventing HO. In the prophylaxis of HO, multiple fractions seem to be more effective than single fraction radiation. Preoperative radiotherapy could prevent HO progression with the same efficacy postoperative.

Applying a clinical decision-making model to a patient with severe shoulder pain ultimately diagnosed as neuralgic amyotrophy

OBJECTIVE AND PURPOSE

Shoulder symptoms are often encountered in physical therapy and a myriad of etiologies can cause these symptoms, either locally or remotely. The purpose of this case report is to describe the physical therapist's differential diagnostic process for a patient with acute and severe onset of shoulder pain. Case Description: The patient was a 37-year-old female with sudden onset of right shoulder pain that awakened her at night. Pain was associated with decreased range of motion and shoulder weakness. Faced with an uncertain diagnosis, the physical therapist followed a systematic approach to clinical decision-making. Outcomes: Neuralgic amyotrophy was the primary diagnostic hypothesis but other causes of shoulder pain could not be ruled out. Conclusion: The clinical decision-making process helped the physical therapist narrow down the differential diagnosis list and make a decision to send the patient for further testing. Magnetic resonance imaging and electromyogram confirmed the diagnosis of neuralgic amyotrophy.

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.

Pronounced Heterotopic Ossifications after Traumatic Hamstring Rupture: Is an Ossification Prophylaxis Useful?

Hamstring injuries include a wide range of injuries and affect mainly athletes with high eccentric loads (football, athletics, rugby, climbing). According to the latest literature, unrecognized traumatic ruptures can cause permanent discomfort and may be associated with a poorer postoperative outcome when delayed surgical therapy is performed. Heterotopic ossifications (HO) after hamstring rupture have been described in individual case reports and smaller studies so far. Heterotopic ossifications are mainly known in hip surgery and elbow fractures. In this case report, a 48-year-old patient presented with an increasing swelling with hardening in the area of the right ischial tuberosity. One year before, an impact trauma was the reason for a traumatic hamstring rupture which was diagnosed with a delay. The HO was excised and the tendon refixed with two suture anchors. By limiting the range of motion with a hip-knee orthosis for 9 weeks, a regular postoperative healing process was observed. Heterotopic ossifications after hamstring ruptures have been reported repeatedly but have not been evaluated in any major study so far. It should therefore be considered whether prophylaxis with NSAIDs should be used for conservatively and surgically treated hamstring ruptures, analogous to the ossification prophylaxis for hip endoprostheses or fractures in the elbow region.

Endogenous CCN family member WISP1 inhibits trauma-induced heterotopic ossification

Heterotopic ossification (HO) is defined as abnormal differentiation of local stromal cells of mesenchymal origin, resulting in pathologic cartilage and bone matrix deposition. Cyr61, CTGF, Nov (CCN) family members are matricellular proteins that have diverse regulatory functions on cell proliferation and differentiation, including the regulation of chondrogenesis. However, little is known regarding CCN family member expression or function in HO. Here, a combination of bulk and single-cell RNA sequencing defined the dynamic temporospatial pattern of CCN family member induction within a mouse model of trauma-induced HO. Among CCN family proteins, Wisp1 (also known as Ccn4) was most upregulated during the evolution of HO, and Wisp1 expression corresponded with chondrogenic gene profile. Immunohistochemistry confirmed WISP1 expression across traumatic and genetic HO mouse models as well as in human HO samples. Transgenic Wisp1LacZ/LacZ knockin animals showed an increase in endochondral ossification in HO after trauma. Finally, the transcriptome of Wisp1-null tenocytes revealed enrichment in signaling pathways, such as the STAT3 and PCP signaling pathways, that may explain increased HO in the context of Wisp1 deficiency. In sum, CCN family members, and in particular Wisp1, are spatiotemporally associated with and negatively regulate trauma-induced HO formation.

Stimulating Factors and Origins of Precursor Cells in Traumatic Heterotopic Ossification Around the Temporomandibular Joint in Mice

The contributing factors and the origins of precursor cells in traumatic heterotopic ossification around the temporomandibular joint (THO-TMJ), which causes obvious restriction of mouth opening and maxillofacial malformation, remain unclear. In this study, our findings demonstrated that injured chondrocytes in the condylar cartilage, but not osteoblasts in the injured subchondral bone, played definite roles in the development of THO-TMJ in mice. Injured condylar chondrocytes without articular disc reserves might secrete growth factors, such as IGF1 and TGFβ2, that stimulate precursor cells, such as endothelial cells and muscle-derived cells, to differentiate into chondrocytes or osteoblasts and induce THO-TMJ. Preserved articular discs can alleviate the pressure on the injured cartilage and inhibit the development of THO-TMJ by inhibiting the secretion of these growth factors from injured chondrocytes. However, the exact molecular relationships among trauma, the injured condylar cartilage, growth factors such as TGFβ2, and pressure need to be explored in detail in the future.

Treatment methods for post-traumatic elbow stiffness caused by heterotopic ossification

HYPOTHESIS

Heterotopic ossification (HO) is a common complication of surgically treated elbow fractures that can inhibit range of motion and impair quality of life. Although there are many treatment methods for HO, there is a lack of consensus as to the best option. We hypothesized that contracture release combined with Botox injection would lead to improved functional outcome scores when compared with current treatment methods.

METHODS

A retrospective review was conducted of patients who presented to a single surgeon with HO secondary to elbow fracture between 2005 and 2018. A total of 59 patients were identified who met inclusion criteria. Data were classified into 3 groups: contracture release (control - CR), Botox injection with CR (Botox + CR), and radiation therapy with CR (CR + RT). Range of motion measurements were obtained, including flexion, extension, pronation, and supination.

RESULTS

A total of 30 patients (30 of 59, 50.8%) received CR, 6 (6 of 59, 9.2%) were treated with CR + RT, and 23 (23 of 59, 40.0%) had CR + Botox. There was a significant difference between pre- and postoperative arc of motion for both CR + RT (P < .01) and CR + Botox (P < .01). In addition, there was a significant difference in pre- and postoperative extension for patients who received intraoperative Botox injections (P < .05). There was no significant difference between pre- and postoperative motion nor extension in the CR group.

CONCLUSION

Intraoperative Botox injection with CR is an effective method in the treatment of post-traumatic elbow stiffness caused by HO.

An unusual case of bowel obstruction in emergency surgery: The heterotopic mesenteric ossification

The heterotopic mesenteric ossification, also known as myositis ossificans, is a rare form of heterotopic ossification, a metaplastic phenomenon where new bone is formed in the mesenteric base, generally after abdominal trauma (surgical or other). The pathophysiology of heterotopic mesenteric ossification is unknown; clinical presentation is not specific, with vague abdominal symptoms, uncertain radiological findings, and often regular laboratory exams. No consensus exists on the best possible approach, although it might well be both medical and surgical. We reviewed the clinical history of a 28-year-old man with a recent motor vehicle accident who was admitted to our surgical unit with symptoms consistent with a small bowel obstruction; after surgery, a diagnosis of myositis ossificans was surprisingly made.

Diffuse Neuritis Ossificans of the Brachial Plexus: Case Report and Review of the Literature

BACKGROUND

Neuritis ossificans (intraneural heterotopic ossification) is a rare disorder described as heterotopic ossification of a nerve. We describe the presentation and management of the first reported case of neuritis ossificans with diffuse brachial plexus involvement and review the literature.

CASE DESCRIPTION

A 35-year-old man presented to our clinic for evaluation of right upper extremity weakness without history of trauma. He had significant, debilitating pain and magnetic resonance imaging demonstrated a complex contrast-enhancing mass with significant associated edema. Positron emission tomography demonstrated a ¹⁸F-fluorodeoxyglucose avid lesion within the brachial plexus that was confirmed by biopsy to be neuritis ossificans. The patient was treated with indomethacin and had clinical and radiologic improvement.

CONCLUSIONS

We present the only case of diffuse, brachial plexus neuritis ossificans. Given the challenges of resecting neuritis ossificans in this region, we believe medical management for complex brachial plexus lesions should be considered first, unless the sequela of the disease is sufficiently prolonged or there is concern for permanent neurovascular compromise.

Post-stroke bilateral heterotopic ossification: An acute problem with long-lasting consequences

Heterotopic ossification (HO) is a complication of injury to the central nervous system in which production of lamellar bone within the soft tissues occurs resulting in pain, reduced range of motion (ROM) and loss of functional capacity. Heterotopic ossification is rarely seen in stroke patients and mostly affects the paretic side. In this article, we present a case of established bilateral HO of the hips soon after stroke onset. A 77-year-old female patient with a five-month history of stroke presented to our rehabilitation clinic. Physical examination revealed sensorimotor aphasia, right-sided hemiplegia, bilateral painful limited ROM of the hips and left knee contracture. An anteroposterior X-ray of the pelvis revealed previously undiagnosed bilateral HO of the hips. The patient and her relatives declined operative interventions. The patient was discussed in the departmental meeting and it was agreed that she would not be able to partake in an active inpatient rehabilitation program. She was discharged with a home exercise plan. This case highlights the importance of HO, of both the paretic and non-paretic side, being included in the differential diagnosis of post-stroke patients presenting with joint pain and reduced ROM, both acutely and in the long-term. This may aid the timely diagnosis and management of HO, a pathology which has detrimental effects on functionality.

Discovery of os cordis in the cardiac skeleton of chimpanzees (Pan troglodytes)

Cardiovascular diseases, especially idiopathic myocardial fibrosis, is one of the most significant causes of morbidity and mortality in captive great apes. This study compared the structure and morphology of 16 hearts from chimpanzees (Pan troglodytes) which were either healthy or affected by myocardial fibrosis using X-ray microtomography. In four hearts, a single, hyperdense structure was detected within the right fibrous trigone of the cardiac skeleton. High resolution scans and histopathology revealed trabecular bones in two cases, hyaline cartilage in another case and a focus of mineralised fibro-cartilaginous metaplasia with endochondral ossification in the last case. Four other animals presented with multiple foci of ectopic calcification within the walls of the great vessels. All hearts affected by marked myocardial fibrosis presented with bone or cartilage formation, and increased collagen levels in tissues adjacent to the bone/cartilage, while unaffected hearts did not present with os cordis or cartilago cordis. The presence of an os cordis has been described in some ruminants, camelids, and otters, but never in great apes. This novel research indicates that an os cordis and cartilago cordis is present in some chimpanzees, particularly those affected by myocardial fibrosis, and could influence the risk of cardiac arrhythmias and sudden death.

Local injection of a hexametaphosphate formulation reduces heterotopic ossification in vivo

Heterotopic ossification (HO), the pathological formation of ectopic bone, is a debilitating condition which can cause chronic pain, limit joint movement, and prevent prosthetic limb fitting. The prevalence of this condition has risen in the military population, due to increased survivorship following blast injuries. Current prophylaxes, which aim to target the complex upstream biological pathways, are inconsistently effective ​and have a range of side-effects that make them unsuitable for combat-injured personnel. As such, many patients must undergo further surgery to remove the formed ectopic bone. In this study, a non-toxic, U.S. Food and Drug Administration (FDA) -approved calcium chelator, hexametaphosphate (HMP), is explored as a novel treatment paradigm for this condition, which targets the chemical, rather that biological, ​bone formation pathways. This approach allows not only prevention of pathological bone formation ​but also uniquely facilitates reversal, which current drugs cannot achieve. Targeted, minimally invasive delivery is achieved by loading HMP into an injectable colloidal alginate. These formulations significantly reduce ​the length of the ectopic bone formed in a rodent model of HO, with no effect on the adjacent skeletal bone. This study demonstrates the potential of localized dissolution as a new treatment ​and an alternative to surgery ​for pathological ossification and calcification conditions.

Goblet Cell Adenocarcinoma With Heterotopic Ossification: A Rare Case Report and Review of Literature

Heterotopic bone formation is a rare phenomenon when associated with gastrointestinal neoplasms. Here we present a rare case of heterotopic ossification associated with goblet cell adenocarcinoma of the appendix, and a literature review of such cases associated with neoplasms within and out of the gastrointestinal tracts. We reviewed the clinical data and when available, immunohistochemical markers of osteoblastic differentiation. Our review shows similar findings to prior reports of apparent high association of heterotopic bone formation with neoplasms with mucinous features. Two, previously proposed main hypotheses of the mechanisms are reviewed. The unique feature about this case is that goblet cell adenocarcinoma was not reported previously in the setting of bone formation.

Serum uric acid level is associated with the incidence of heterotopic ossification following elbow trauma surgery

BACKGROUND

Heterotopic ossification (HO) is a common complication after surgery for elbow trauma. Uric acid is the end product of purine metabolism and has several physiological and pathogenic roles. However, the relationship between HO and uric acid has not been explored. This retrospective study aimed to assess the relationship between HO and serum uric acid (SUA).

MATERIAL AND METHODS

We retrospectively reviewed data from 155 patients undergoing elbow trauma surgery in our hospital between January 2013 and December 2018. One hundred patients were included according to the inclusion criteria. They were divided into 2 groups according to the presence or absence of HO, and the SUA level was compared between groups using the independent samples t test. The optimal prognostic cutoff value was obtained using the maximum value of the Youden index.

RESULTS

The SUA level was significantly higher in the HO group than in the non-HO group (362.0 ± 87.4 μmol/L vs. 318.3 ± 87.0 μmol/L; P < .05). Using the maximum value of Youden index, 317.5 μmol/L was determined to be the optimal SUA cutoff value for the prediction of HO, with a sensitivity of 68.75% (95% confidence interval [CI], 54.67%-80.05%) and specificity of 55.77% (95% CI, 42.34%-68.40%).

CONCLUSIONS

Our study was the first to find that the high SUA level is a risk factor for HO of the elbow joint after trauma. Moreover, 317.5 μmol/L is the SUA threshold predicting the occurrence and development of HO of the elbow, with high sensitivity and specificity.