Heterotopic ossification as rare complication of hemiplegia following stroke: two cases

Modified Ludloff's medial approach for resection of heterotopic ossification of the hip following severe SARS-CoV-2 infection: a case report

The coronavirus disease 2019 pandemic has significantly affected people worldwide. Herein, we present a case of massive heterotopic ossification (HO) of the right hip following severe SARS-CoV-2 infection. The exact origin of HO development is still unknown, but a critical illness, chronic immobilization and hypoxia are important risk factors. Considering the location and size of the HOs in this case, modified Ludloff's medial approach of the hip was used. This approach allows for good exposure and access to the medial and inferior part of the hip joint and the successful extirpation of the pathologic tissue.

Effectiveness of Prophylactic Interventions in Neurogenic Heterotopic Ossification (NHO): A Systematic Review

Neurogenic heterotopic ossification (NHO) is the formation of mature lamellar bone in peri-articular tissues following a neurological insult, most commonly traumatic brain injury (TBI) or spinal cord injury (SCI). NHO is a debilitating condition associated with significant morbidity and reduced quality of life. However, its pathophysiology remains poorly understood. While surgery is the mainstay of treatment once NHO has been diagnosed, prophylactic options are limited and not well studied. This review aimed to determine the efficacy of various interventions used in the primary prevention of NHO. We conducted an electronic literature search using five databases (PubMed, Embase, ScienceDirect, Cochrane Library, and Cumulative Index to Nursing and Allied Health Literature (CINAHL)) for records published until April 10, 2022. We identified 2,610 potentially eligible records across all databases. Nine reports met our eligibility criteria and were included in this review. Four were clinical trials (three randomized control trials, one nonrandomized trial), four were observational studies, and one was a systematic review/meta-analysis. The medications/interventions used included: warfarin, pulse low-intensity electromagnetic field therapy (PLIMF), bisphosphonates, and nonsteroidal anti-inflammatory drugs (NSAIDs). We did not find conclusive evidence to recommend the use of bisphosphonates and warfarin in the prevention of NHO. On the contrary, we found NSAIDs and PLIMF as effective prophylactic options based on the results of high-quality randomized control trials. Further prospective randomized studies with prolonged follow-ups are needed to confirm the long-term efficacy of these preventive interventions.

Single-Cell Integration Analysis of Heterotopic Ossification and Fibrocartilage Developmental Lineage: Endoplasmic Reticulum Stress Effector Xbp1 Transcriptionally Regulates the Notch Signaling Pathway to Mediate Fibrocartilage Differentiation

INTRODUCTION

Regeneration of fibrochondrocytes is essential for the healing of the tendon-bone interface (TBI), which is similar to the formation of neurogenic heterotopic ossification (HO). Through single-cell integrative analysis, this study explored the homogeneity of HO cells and fibrochondrocytes.

METHODS

This study integrated six datasets, namely, GSE94683, GSE144306, GSE168153, GSE138515, GSE102929, and GSE110993. The differentiation trajectory and key transcription factors (TFs) for HO occurrence were systematically analyzed by integrating single-cell RNA (scRNA) sequencing, bulk RNA sequencing, and assay of transposase accessible chromatin seq. The differential expression and enrichment pathways of TFs in heterotopically ossified tissues were identified.

RESULTS

HO that mimicked pathological cells was classified into HO1 and HO2 cell subsets. Results of the pseudo-temporal sequence analysis suggested that HO2 is a differentiated precursor cell of HO1. The analysis of integrated scRNA data revealed that ectopically ossified cells have similar transcriptional characteristics to cells in the fibrocartilaginous zone of tendons. The modified SCENIC method was used to identify specific transcriptional regulators associated with ectopic ossification. Xbp1 was defined as a common key transcriptional regulator of ectopically ossified tissues and the fibrocartilaginous zone of tendons. Subsequently, the CellPhoneDB database was completed for the cellular ligand-receptor analysis. With further pathway screening, this study is the first to propose that Xbp1 may upregulate the Notch signaling pathway through Jag1 transcription. Twenty-four microRNAs were screened and were found to be potentially associated with upregulation of XBP1 expression after acute ischemic stroke.

CONCLUSION

A systematic analysis of the differentiation landscape and cellular homogeneity facilitated a molecular understanding of the phenotypic similarities between cells in the fibrocartilaginous region of tendon and HO cells. Furthermore, by identifying Xbp1 as a hub regulator and by conducting a ligand-receptor analysis, we propose a potential Xbp1/Jag1/Notch signaling pathway.

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.

Troublesome heterotopic ossification and stroke: Features and risk factors. A case control study

PRIMARY OBJECTIVE

To determine the features of stroke-related HO in a large sample of patients and to assess if HO risk is increased by haemorrhagic stroke.

RESEARCH DESIGN

A case control study (risk factor of a rare event using retrospective analysis).

METHODS AND PROCEDURES

Sixty-one patients with stroke-81 troublesome HOs-were included, each was matched with four controls, i.e. 244 patients with no HO after stroke. Matching criteria were age (±3.5 years) and sex. Data recorded were time from stroke to surgery, ischaemic or haemorrhagic stroke and presence of HO risk factors.

MAIN OUTCOMES AND RESULTS

Mean age at time of stroke = 46.02 ± 11.4 years (15.9-76.3) for the case sub-group. Time from stroke to surgery = 23.4 ± 27.8 months (3.6-150.0). There was a significant relationship between haemorrhagic stroke and HO development (OR = 3.01; 95% CI = 1.14-7.98; p < 0.05), but not for ischaemic stroke. This became non-significant when all matching and risk factors were included in the model (adjusted OR = 1.98; 95% CI = 0.60-6.54; p = 0.26).

CONCLUSION

Haemorrhagic stroke appears to increase the risk of HO development. Further studies are required to determine if this risk factor is independent from other comorbid factors.