Serial Ultrasonography for Early Detection and Follow-up of Heterotopic Ossification in Stroke

Pediatric Heterotopic Ossification: A Comprehensive Review

PURPOSE OF REVIEW

The purpose of this review is to provide a comprehensive analysis of heterotopic ossification (HO) in pediatric patients, including an in-depth examination of the risk factors associated with this condition, current prophylactic measures, and available management strategies.

RECENT FINDINGS

HO is a medical disorder in which bone tissue inexplicably develops in soft tissues such as muscles and tendons. It involves the formation of mature, lamellar bone in extra-skeletal soft tissue, and its formation is influenced by oxygen tension, pH, the availability of micronutrients, and mechanical stimulation. HO has many cellular origins, with the most common theory being multipotent cells in local tissue. The diagnosis of HO is typically made based on exam, radiographs, and CT. Management includes both prophylactic nonsurgical options and surgical resection for severe or recalcitrant cases. The review highlights the incidence, risk factors, and management strategies associated with HO in pediatric patients. HO is a rare condition in children, with severe neurologic injury being the most common cause. Pediatric patients most commonly develop HO following severe neurologic injury, followed by trauma and surgery. Current prophylactic measures, include nonsteroidal anti-inflammatory drugs and radiation therapy though limited literature on their use in the pediatric population exists. For recalcitrant symptomatic cases, wide surgical resection can be considered but has a higher risk profile and associated morbidity. This review highlights the need for further pediatric specific research to inform guidelines and management strategies for this debilitating condition.

Bedside Ultrasound to Facilitate Early Diagnosis and Ease of Follow-Up in Neurogenic Heterotopic Ossification: A Pilot Study From the Intensive Care Unit

OBJECTIVE

To explore the potential role of ultrasound (US) as a bedside tool in intensive care unit patients with presumed neurogenic heterotopic ossification (NHO).

SETTING

Tertiary university teaching hospitals.

PARTICIPANTS

Critical care patients with acquired brain injury.

DESIGN

A multicenter prospective study of critical care patients with possible NHO.

MAIN MEASURES

Following a screening clinical examination, the major joints were evaluated with US, serum laboratory work, and x-ray.

RESULTS

A total of 310 patients had decreased range of motion by clinical screen and all received US interrogation. Sonographic signs of NHO were identified in 21 of the 310 patients (6.8%), of which 17/21 (81.0%) showed hyperemia; 9/21 (42.8%) showed the reverse zone phenomenon, and 4/21 patients (19.0%) showed the prezone phenomenon. All 21 patients progressed to the zone phenomenon within 15 weeks. Laboratory parameters were not significantly correlated with US (r = 0.11, r = 0.13; P > .05, respectively), whereas x-rays were associated with a mean diagnostic delay of 2 ± 0.5 weeks (P < .05) compared with US. All 21 sonographic NHO patients survived to intensive care unit discharge. Twelve months after admission, 3/21 had died; 6/21 still had abnormalities by x-ray, US, and clinical examination; and 12/21 had resolution by x-ray, US, and clinical examination.

CONCLUSION

Our pilot study suggests potential benefits for bedside US in NHO, especially when compared with x-ray or laboratory investigations. These include the possibility of earlier diagnosis, consideration of therapy before ossification, and ease of follow-up. Our study also provides insights into the morphologic, sonographic, radiologic, and clinical course of NHO.

The development and impact of heterotopic ossification in burns: a review of four decades of research

Background to this subject:

Heterotopic ossification (HO) is the formation of bone within the tissue where bone should not form and is a rare complication after burn injury. However, it leads to severe pain and distress, marked reduction in joint range of motion (ROM), impaired function and increased hospital length of stay. The pathophysiology, incidence and risk factors of HO remain poorly understood in burns and other traumas and the management, controversial.

Question being asked or issue explored:

The aim of this comprehensive review was to synthesise the available evidence on the development and treatment of HO after acute burn injury.

Details of how the work was conducted:

The review was based on a systematic search of medical electronic databases to identify relevant published literature.

What we did and did not learn from this study:

Synthesis and analysis of the data highlighted that, despite the passage of time, little translatable evidence is available to guide any prevention, screening, diagnostic or pharmacological or physical management protocols. Causes of HO remain confounded, therefore prevention is difficult. Although spontaneous resolution is possible, surgical resection remains the recommended treatment when ROM and activities of daily living are severely affected. The findings from this review indicate that multicentre data pooling is needed to understand the optimum pathway to prevention, identification and treatment of HO in acute burn patients.

Ultrasonic bone localization algorithm based on time-series cumulative kurtosis

The design and optimization of protective equipment and devices such as exoskeletons and prosthetics have the potential to be enhanced by the ability of accurately measure the positions of the bones during movement. Existing technologies allow a quite precise measurement of motion-mainly by using coordinate video-cameras and skin-mounted markers-but fail in directly measuring the bone position. Alternative approaches, as fluoroscopy, are too invasive and not usable during extended lapses of time, either for cost or radiation exposure. An approach to solve the problem is to combine the skin-glued markers with ultrasound technology in order to obtain the bone position by measuring at the same time the marker coordinates in 3D space and the depth of the echo from the bone. Given the complex structure of the bones and the tissues, the echoes from the ultrasound transducer show a quite complex structure as well. To reach a good accuracy in determining the depth of the bones, it is of paramount importance the ability to measure the time-of-flight (TOF) of the pulse with a high level of confidence. In this paper, the performance of several methods for determining the TOF of the ultrasound pulse has been evaluated when they are applied to the problem of measuring the bone depth. Experiments have been made using both simple setups used for calibration purposes and in real human tissues to test the performance of the algorithms. The results show that the method used to process the data to evaluate the time-of-flight of the echo signal can significantly affect the value of the depth measurement, especially in the cases when the verticality of the sensor with respect to the surface causing the main echo cannot be guaranteed. Finally, after testing several methods and processing algorithms for both accuracy and repeatability, the proposed cumulative kurtosis algorithm was found to be the most appropriate in the case of measuring bone depths in vivo with ultrasound sensors at frequencies around 5MHz.