Does Excision of Heterotopic Ossification of the Elbow Result in Satisfactory Patient-Rated Outcomes?

Treatment of an Ulnar Fracture Bone Defect Using Heterotopic Bone Autograft: A Case Report

CASE

Autologous bone grafting has wide applications for the treatment of bony defects. Generally, cancellous or corticocancellous bone grafts are used depending on the characteristics and size of the bony defect and wound bed. The use of heterotopic bone as a potential source of bone graft has not been widely reported. We present a 56-year-old right-hand-dominant male victim of dog mauling who sustained a right ulnar fracture with a 5-cm bony defect, treated with the use of heterotopic bone autograft.

CONCLUSION

Heterotopic bone can be successfully used as an autograft in the treatment of bony defects.

Neuron-to-vessel signaling is a required feature of aberrant stem cell commitment after soft tissue trauma

The functional interdependence of nerves and blood vessels is a well-established concept during tissue morphogenesis, yet the role of neurovascular coupling in proper and aberrant tissue repair is an emerging field of interest. Here, we sought to define the regulatory relationship of peripheral nerves on vasculature in a severe extremity trauma model in mice, which results in aberrant cell fate and heterotopic ossification (HO). First, a high spatial degree of neurovascular congruency was observed to exist within extremity injury associated heterotopic ossification. Vascular and perivascular cells demonstrate characteristic responses to injury, as assessed by single cell RNA sequencing. This vascular response to injury was blunted in neurectomized mice, including a decrease in endothelial proliferation and type H vessel formation, and a downregulation of key transcriptional networks associated with angiogenesis. Independent mechanisms to chemically or genetically inhibit axonal ingrowth led to similar deficits in HO site angiogenesis, a reduction in type H vessels, and heterotopic bone formation. Finally, a combination of single cell transcriptomic approaches within the dorsal root ganglia identified key neural-derived angiogenic paracrine factors that may mediate neuron-to-vascular signaling in HO. These data provide further understanding of nerve-to-vessel crosstalk in traumatized soft tissues, which may reflect a key determinant of mesenchymal progenitor cell fate after injury.

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.

Comparing Options for Heterotopic Ossification Prophylaxis following Elbow Trauma: A Systematic Review and Meta-Analysis

Introduction  Heterotopic ossification (HO) can be a potentially serious and devastating complication following traumatic injury to the elbow. HO prophylaxis options include nonsteroidal anti-inflammatory drugs (NSAIDs) and radiation therapy (RT) but neither has been proven more effective. The purpose of this review is to compare effectiveness and outcomes between NSAID and RT prophylaxis for HO about the elbow following a traumatic injury. Materials and Methods  We performed a systematic review of PubMed and Cochrane Library for cases of HO prophylaxis following elbow trauma utilizing PRISMA guidelines to determine the most effective form of prophylaxis. Outcomes of interest included recurrence of HO, range of motion (ROM), and Mayo elbow performance index (MEPI). A total of 36 articles and 826 elbows of which 203 received RT and 623 received NSAID were identified and included in the final analysis. Results  Rates of HO formation or recurrence following elbow trauma were similar between radiation and NSAID prophylaxis (15.6% vs. 22.2%, respectively p = 0.457). ROM was similar in flexion and extension arc (109.0 degrees in radiation vs. 112.8 in NSAIDs, p = 0.459) and in pronation and supination arc (118.9 degrees radiation vs. 134.7 degrees NSAIDs, p = 0.322). MEPI scores were 79.19 in the radiation group and 88.82 in the NSAIDs group at the final follow-up. Conclusion  There is no statistical difference in HO development, recurrence, or final ROM between NSAIDs and RT prophylaxis following trauma to the elbow. We recommend the choice of modality based on patient characteristics, cost, and surgeon preference. Level of Evidence  Level III.

Neglected posterior dislocation of elbow: A review

Untreated traumatic posterior dislocation of the elbow joint, 3 weeks or older, is defined as "neglected posterior dislocation of the elbow". Around 90% of these are of posterolateral type. These are much more common in the developing and underdeveloped countries. Patients presents with a deformed, stiff and painful elbow with difficulty to perform activities of daily living. The clinical picture looks quite similar to malunited supracondylar fracture of the elbow. Diagnosis is usually confirmed radiographically. CT and MRI scan give additional information and are recommended before embarking on surgery. Treatment is quite challenging due to the significant soft tissue contractures, ligamentous insufficiencies and fibrosis, with possible associated nerve injuries, myositis ossificans, non-compliant patients and the need for long-term postoperative physiotherapy. Goal of surgical treatment is to achieve a painless, stable and mobile elbow with a congruent joint space. We have reviewed the literature and present our view on the prognosis and recommended surgical technique to treat this condition.

Heterotopic Ossification: A Comprehensive Review

Heterotopic ossification (HO) is a diverse pathologic process, defined as the formation of extraskeletal bone in muscle and soft tissues. HO can be conceptualized as a tissue repair process gone awry and is a common complication of trauma and surgery. This comprehensive review seeks to synthesize the clinical, pathoetiologic, and basic biologic features of HO, including nongenetic and genetic forms. First, the clinical features, radiographic appearance, histopathologic diagnosis, and current methods of treatment are discussed. Next, current concepts regarding the mechanistic bases for HO are discussed, including the putative cell types responsible for HO formation, the inflammatory milieu and other prerequisite “niche” factors for HO initiation and propagation, and currently available animal models for the study of HO of this common and potentially devastating condition. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.