Histology of neurogenic heterotopic ossification and comparison with its radiological expression in acute spinal cord injured patients.

Abstract

Study design: Clinical prospective study.

Objectives: To histologically examine puncture biopsies of early neurogenic heterotopic ossification (NHO) in spinal cord injured individuals.

Setting: University of Bochum, Germany.

Methods: After acute spinal trauma, participants underwent a sonographic examination of the hip joints and a routine laboratory examination. Magnetic resonance imaging (MRI) or computed tomography (CT) of the pelvis was performed if there were clinical and laboratory signs of NHO and sonographic evidence of edema and/or calcifications in the tissue around the hip joint. If NHO were detected, tissue was obtained and preserved for histological examination from the involved tissue around the hip joint affected by NHO and from an unaffected calf as control. Nine participants with a complete spinal cord lesion American Spinal Injury Association Impairment Scale (AIS) grade A and evidence of an acute NHO in the hip joint muscles were recruited for the study.

Results: In all sonographic examinations of the hip joint, edematous changes could be detected. In one case, calcifications were detected sonographically. In MRI/CT in six participants, ossification could already be detected. All histological specimens from the NHO-affected gluteal region showed varying degrees of tissue deformation. The unaffected reference samples showed regular muscular structure microscopically.

Conclusions: It was possible to show and compare histological changes in NHO-affected tissue with MRI/CT imaging, depending on the stage of NHO.

Trial registration: DRKS, DRKS00034049. Registered 12 April 2024 - Retrospectively registered, https://www.drks.de/DRKS00034049 .