Neurogenic heterotopic ossification of the hip: Magnetic resonance imaging versus computed tomography for pre-surgical assessment.

PURPOSE: Neurogenic heterotopic ossification (NHO) of the hip is a frequent complication of spinal cord injuries, often requiring surgical management. Pre-surgical imaging assessment is essential, usually with computed tomography (CT)-scan. We aimed to compare magnetic resonance imaging (MRI) and CT for pre-surgical imaging assessment of the NHO, particularly for their relationships with vessels and nerves. METHOD: This prospective study included consecutive patients who underwent surgery for NHO from July 2019 to April 2022. All patients had CT angiography and MRI including Zero Echo Time and TRICKS sequences. Radiologists used standardized reports for CT and MRI to evaluate NHO and their features, bone mineralization, and relation to the arteries, veins and nerves. Agreement between pre-surgical CT and MRI was evaluated. RESULTS: Twenty-four patients (mean age: 53.5 ± 12.2 years) were included, among which 7 had bilateral NHO (31 hips). NHO were anterior in 15/31 hips (48 %), multifragmented in 25/31 hips (81 %). Mild and significant demineralization was most frequent. Gutter and tunnel were reported in 11.1 % of the arteries. Nerves were more often identified in MRI than in CT-scan. Agreement coefficients between CT and MRI were excellent for NHO location (0.95) and implantation (0.92), good for fragmentation (0.70), contact with joint capsule (0.66), bone mineralization (0.74), and relation to arteries (0.85), veins (0.76), sciatic nerve (0.7) and moderate for femoral nerve (0.47). CONCLUSION: MRI exhibited a good agreement with CT for pre-surgical assessment of NHO of the hip, especially to evaluate their relationships with the arteries, veins and sciatic nerve. Femoral nerves were more often identified in MRI than in CT-scan.

Comparison of magnetic resonance imaging and computed tomography for bone assessment of neurogenic heterotopic ossification of the hip: a preliminary study.

BACKGROUND: Neurogenic heterotopic ossification (NHO) is a frequent complication, often involving the hip. The functional impact may require surgical management and pre-surgical imaging assessment is necessary, usually by computed tomography (CT). We aimed to compare the performances of magnetic resonance imaging (MRI) and CT for bone assessment on pre-surgical imaging of the heterotopic ossifications and their features in NHO of the hip. METHODS: This single-center prospective preliminary study included all patients who underwent surgery for NHO with joint limitation from July 2019 to March 2020. All patients had a CT after biphasic iodinated solution injection and an MRI including T1-weighted, STIR and ZTE sequences. Standardized reports were completed for both exams for each patient, evaluating location, implantation and fragmentation of NHO, relation to the joint capsule and bone mineralization, then were compared. RESULTS: Seven patients from 32 to 70 years old (mean = 50.2 ± 17.2 years) were evaluated. NHO were bilateral in 2 patients, for a total of nine hips: six right hips and three left hips. Observed concordance rates between MRI and CT were, respectively, 94.4% for location, 100% for circumferential extension, 87.3% for implantation 88.9% for fragmentation, 77.8% for relation to the joint capsule and 66.7% for bone mineralization. It was 100% for femoral neck fracture and osteonecrosis of the femoral head. CONCLUSION: This preliminary study suggests that pre-surgical MRI imaging should be considered as effective as CT for bone assessment of NHO and their features. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03832556. Registered February 6, 2019, https://clinicaltrials.gov/ct2/show/NCT03832556 .

The Assessment of Paravertebral Ossification Progression After Cervical Disc Arthroplasty Based on CT Images: A Long-term Follow-up.

OBJECTIVE: This study focused on the assessment of paravertebral ossification (PO) after cervical disc arthroplasty (CDA) using computed tomography (CT) images. METHODS: In this retrospective study, 52 patients (from 2004 to 2010) who received CDA at a single center were included (32 males). Preoperative and follow-up X-ray and CT images of all patients who underwent single-level CDA were collected. PO from the C2/3 to C7/T1 in each patient was graded based on a CT grading system. Each segment was divided into operative level, adjacent level, or non-adjacent level. The McAfee' classification system was used to grade PO using X-ray plain film. The range of motion (ROM) and scores of neurological symptoms (Japanese Orthopaedic Association [JOA] score and Neck Disability Index [NDI]) at both preoperative and final follow-up time were acquired. Progression and classification of PO in each group was compared using the chi-square test. ROM between groups were compared using independent t-test. JOA score and NDI between groups were compared using Mann-Whitney U test. RESULTS: The average follow-up time was 81.2 months. In comparison with the preoperative status, the progression of PO development in left and right areas (the Luschka joints areas) in the operative level groups was significantly more severe (area L,χ2 value = 36.612, P < 0.001; area R, χ2 value = 39.172, P < 0.001) than the non-adjacent level groups. In contrast, although the prevalence of PO in all areas of the adjacent level groups was higher than that of the non-adjacent level group in the same segments, there was no significant difference (P > 0.05) in the progression of PO development. The follow-up high-grade (grades III and IV) PO incidence rate using X-ray grading system (3.85%) was significantly lower than that using CT grading system in area L (42.31%) and R (38.46%), but close to that in area A (5.77%) and P (1.92%). The final follow-up ROM was not significantly different with preoperative ROM in patients with low-grade PO (9.47° ± 4.12° vs. 9.76° ± 3.69°, P = 0.794). However, in patients with high-grade PO, the final follow-up ROM was significantly lower than preoperative ROM (5.77° ± 3.32° vs. 9.28° ± 4.15°, P < 0.001). There was no significant difference for JOA score and NDI at follow-up between patients with high-grade and low-grade PO (JOA, 16.2 ± 1.1 vs. 16.8 ± 0.9, P = 0.489; NDI, 8.9 ± 6.1 vs. 8.0 ± 7.3, P = 0.317). CONCLUSION: High-grade PO was observed in the areas of the Luschka joints at the operative level after CDA, which was difficult to observe using X-ray plain film. The PO formation at adjacent segments was not significant.

Morphological assessment of the stylohyoid complex variations with cone beam computed tomography in a Turkish population.

BACKGROUND: The aim of this investigation was to evaluate the length, thickness, sagittal and transverse angulations and the morphological variations of the stylohyoid complex (SHC), to assess their probable associations with age and gender, and to investigate the prevalence of it in a wide range of a Turkish sub-population by using cone beam computed tomography (CBCT). MATERIALS AND METHODS: The CBCT images of the 1000 patients were evaluated retrospectively. The length, thickness, sagittal and transverse angulations, morphological variations and ossification degrees of SHC were evaluated on multiplanar reconstructions (MPR) adnd three-dimensional (3D) volume rendering (3DVR) images. The data were analysed statistically by using nonparametric tests, Pearson's correlation coefficient, Student's t test, c2 test and one-way ANOVA. Statistical significance was considered at p < 0.05. RESULTS: It was determined that 684 (34.2%) of all 2000 SHCs were elongated (> 35 mm). The mean sagittal angle value was measured to be 72.24° and the mean transverse angle value was 70.81°. Scalariform shape, elongated type and nodular calcification pattern have the highest mean age values between the morphological groups, respectively. Calcified outline was the most prevalent calcification pattern in males. There was no correlation between length and the calcification pattern groups while scalariform shape and pseudoarticular type were the longest variations. CONCLUSIONS: We observed that as the anterior sagittal angle gets wider, SHC tends to get longer. The most observed morphological variations were linear shape, elongated type and calcified outline pattern. Detailed studies on the classification will contribute to the literature. (Folia Morphol 2018; 77, 1: 79-89).

Imaging assessment of fibrodysplasia ossificans progressiva: Qualitative, quantitative and questionable.

Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare autosomal dominant genetic disorder of heterotopic ossification (HO) characterized by skeletal anomalies and episodic soft tissue swelling (flare-ups) that can transform into heterotopic bone. The progressive development of heterotopic bone and progressive arthropathy leads to significant limitation of mobility. This paper will review various imaging modalities used in evaluating episodic soft tissue swelling (flare-ups), heterotopic bone and skeletal anomalies. Different imaging modalities are required at different stages of the disease. Ultrasound and MRI can be useful for evaluating edema in early stages of a flare-up; MRI being superior to ultrasonography. Plain radiographs and computed tomography (CT) can evaluate heterotopic bone in later stages of HO, but CT scan is better at evaluating presence and the volume of heterotopic bone. Functional imaging demonstrates increased activity at sites of flare-ups, their utility in determining disease progression need to be further evaluated. Cost, radiation exposure, availability of various imaging modalities and the ability of FOP patients to fit in the scanner are all considerations when requesting radiographic tests in a patient with FOP. Future studies are required to determine if early radiographic findings can determine disease progression and response to treatment in this disorder.

Analog Method for Radiographic Assessment of Heterotopic Bone in Fibrodysplasia Ossificans Progressiva.

RATIONALE AND OBJECTIVES: Severe progressive multifocal heterotopic ossification (HO) is a rare occurrence seen predominantly in patients who have fibrodysplasia ossificans progressiva (FOP) and is difficult to quantitate owing to patient-, disease-, logistical-, and radiation-related issues. The purpose of this study was to develop and validate a scoring system based on plain radiographs for quantitative assessment of HO lesions in patients with FOP. MATERIALS AND METHODS: Institutional review board approval was obtained from the University of Pennsylvania, and all data comply with Health Insurance Portability and Accountability Act regulations. The University of Pennsylvania Institutional Animal Care and Use Committee approved the use of mice in this study. First, we used a mouse model of FOP-like HO to validate a semiquantitative analog scale for estimating relative heterotopic bone volume. Second, we used this validated scale to estimate the relative amount of HO from a retrospective analysis of plain radiographs from 63 patients with classic FOP. Finally, the scale was applied to a retrospective analysis of computed tomographic images from three patients with FOP. RESULTS: In the FOP-mouse model, the observed rating on the analog scale is highly correlated to heterotopic bone volumes measured by microcomputed tomography (R2 = 0.89). The scoring system that was applied to radiographs of patients with FOP captured the clinical range of HO typically present at all axial and appendicular sites. Analysis of computed tomographic scans of patients with FOP found that observed radiograph ratings were highly correlated with HO volume (R2 = 0.80). CONCLUSIONS: The scoring system described here could enable practical, quantitative assessment of HO in clinical trials to evaluate new treatment modalities, especially for FOP. The development of the six-point analog scale described here provides and validates a much-needed, reproducible, and quantifiable method for describing and assessing HO in patients with FOP. This scale has the potential to be a key descriptor that can inform patients with FOP and clinicians about disease progression and response of HO lesions to interventions and treatments.

Pre-surgical CT-assessment of neurogenic myositis ossificans of the hip and risk factors of recurrence: a series of 101 consecutive patients.

BACKGROUND: Neurogenic Myositis Ossificans (NMO) is a rare disabling pathology characterized by peri-articular heterotopic ossifications following severe peripheral or central nervous system injuries. It results in ankylosis and vessels or nerves compressions. Our study aimed to describe the pre-operative findings of patients with NMO of the hip using biphasic computerized tomography (CT). METHODS: Between 2006 and 2012, we retrospectively analyzed 101 consecutive patients with hip NMO. We analyzed all CTs and surgical reports following a standardized grid depicting the osteoma and its relations with joint capsule, vessels and nerves and bone mineralization. We studied surgical complications and recurrence during follow-up. Chi2-test and Fischer's test were performed to compare qualitative values with respectively normal and non-normal distribution. Quantitative values were analyzed with a one factor analysis of variance (ANOVA) test. Agreement between pre-surgical CT and surgical observations was evaluated with Cohen's kappa test. RESULTS: Correlation between pre-operative CT and surgical findings was excellent regarding relationships with vessels (0,82) and was good concerning relationships with sciatic nerves (0.62) and with joint capsule (0.68). Close contact or disruption of joint capsule (p = 0.005), joint space narrowing (p = 0.007) and bone demineralization (p < 0.001) were correlated with NMO recurrence. CONCLUSIONS: Biphasic enhanced-CT allows pre-operative assessment of NMO with good correlation to surgical observations and helps prevent surgical complications.

Anatomic and Quantitative Temporal Bone CT for Preoperative Assessment of Branchio-Oto-Renal Syndrome.

We describe the temporal bone computed tomography (CT) findings of an unusual case of branchio-oto-renal syndrome with ectopic ossicles that are partially located in the middle cranial fossa. We also describe quantitative temporal bone CT assessment pertaining to cochlear implantation in the setting of anomalous cochlear anatomy associated with this syndrome.

A new classification of peri-articular heterotopic ossification of the hip associated with neurological injury: 3D CT scan assessment and intra-operative findings.

In this paper we propose a new classification of neurogenic peri-articular heterotopic ossification (HO) of the hip based on three-dimensional (3D) CT, with the aim of improving pre-operative planning for its excision. A total of 55 patients (73 hips) with clinically significant HO after either traumatic brain or spinal cord injury were assessed by 3D-CT scanning, and the results compared with the intra-operative findings. At operation, the gross pathological anatomy of the HO as identified by 3D-CT imaging was confirmed as affecting the peri-articular hip muscles to a greater or lesser extent. We identified seven patterns of involvement: four basic (anterior, medial, posterior and lateral) and three mixed (anteromedial, posterolateral and circumferential). Excellent intra- and inter-observer agreement, with kappa values > 0.8, confirmed the reproducibility of the classification system. We describe the different surgical approaches used to excise the HO which were guided by the 3D-CT findings. Resection was always successful. 3D-CT imaging, complemented in some cases by angiography, allows the surgeon to define the 3D anatomy of the HO accurately and to plan its surgical excision with precision.

Radiographic and computed tomographic assessment of the development of the antebrachia and elbow joints in Labrador Retrievers with and without medial coronoid disease.

OBJECTIVES: To compare the development, monitored by radiography and computed tomography, of the antebrachia and elbow joints in seven Labrador Retrievers with healthy elbow joints and in seven Labrador Retrievers that developed medial coronoid disease (MCD), in order to determine whether disturbances in the development of the antebrachia and elbow joints, between the age of six and 17 weeks may lead to medial coronoid disease. METHODS: A prospective study of 14 Labrador Retrievers in their active growth stage was performed. The development of the antebrachia and elbow joints was assessed between six and 17 weeks of age using radiography and computed tomography determining the development of secondary ossification centres, radioulnar length ratio, radial angulation, and inter-relationship between the humerus, ulna and radius. RESULTS: For the parameters of ossification of secondary ossification centres, radioulnar length ratio, radial angulation, and joint congruence evaluation, there was no significant difference in the development of the antebrachia and elbow joints of seven Labrador Retrievers positive and seven Labrador Retrievers negative for MCD at the age of six to 17 weeks. CLINICAL SIGNIFICANCE: These findings demonstrate that the development of MCD in the Labrador Retrievers in our study was not related to any disturbance in the development of the antebrachia and elbow joints during the rapid growth phase.

[Long follow-up radiological assessment of the cemented hip prosthesis]. / Odlegla ocena radiologiczna endoprotezoplastyki cementowej stawu biodrowego.

MATERIALS AND METHODS: The postoperative and last follow-up radiograms: 7 to 25 years after surgery (mean: 10.4 +/- 3.9) were evaluated in 123 patients (167 hips). The radiological evaluation was performed according to Hip Society recommendations. The position of the cup and the stem, polyethylene wear, the migration of the cup or stem, radiolucent lines and ectopic ossification were evaluated. RESULTS: At last follow-up in 17 hips a prior revision was performed and further radiological assessment revealed 16 cases of prosthesis loosening. The retrospective analysis of the postoperative radiograms of 33 hips with loosening revealed radiolucent lines around the cup in de-Lee zones I, II, III respectively in 5, 2, 5 hips where in patients without loosening radiolucent lines were found in respectively 11, 4, 17 hips. The correlation between the cup or stem positioning and the rate of loosening was not significant. Fracture of the cup cement was found in 5 hips and radiolucent line around the cup cement in I, II and III zone of deLee was found respectively in 70, 26, 52 hips at last follow-up. No polyethylene wear was found in 77 hips when mean wear of 2.9 mm was found in the rest. The radiolucent line was most often detected in Gruen zones 3, 9 and 10. The ectopic ossification was found in 67% hips at last follow-up. CONCLUSIONS: The radiolucent line around the cup is more often detected on postoperative radiograms in patients with early cup loosening but this correlation is not so clear in stem loosning. The increased osteolysis around the implant as well as ectopic ossifications are found in long follow-up of the cemented hip prosthesis.

Cavovarus foot deformity with multiple tarsal coalitions: functional and three-dimensional preoperative assessment.

In rare instances, tarsal coalition leads to cavovarus foot deformity, although the pathologic mechanism leading to this deformity is not clear. This article reports a case of a 14-year-old boy presenting a severe cavovarus deformity of the right foot with talocalcaneal and calcaneonavicular coalitions, and a mild cavus deformity of the left foot with a single talocalcaneal coalition. Computed tomography and postoperative histologic analysis demonstrated a synostosis between talus and calcaneus and a fibrous calcaneonavicular coalition with partial ossification. Instrumented gait analysis revealed a limited range of ankle plantar flexion and increased external rotation of the ankle. Associated skeletal malformations including incomplete hemimelia of the forearm and scoliosis raised the possibility of a teratologic condition, but neurologic examination, spinal magnetic resonance imaging, and nerve conduction velocities were normal. The progressive ossification of combined coalitions during growth of the foot may have been one factor leading to this complex foot deformity. The fine-wire electromyogram showed normal tibialis anterior and posterior muscle activity. Small soft tissue tears in the sinus tarsi may have led to a mild reflexive increase of the muscle tone and tendon shortening, which pulled the forefoot into adduction and the heel into varus, and raised the medial arch. Mechanical alterations of the ankle appear secondary to the heel varus and to the progressive deformity of the talus. Three-dimensional computed tomography reconstruction and gait analysis appeared to be helpful additional parameters to understanding the pathomechanics of this complex foot deformity and for preoperative planning of triple arthrodesis.

[Digital planimetry for exact assessment of peri-articular ossification]. / Die digitalisierte Planimetrie zur exakten Erfassung von periartikulären Ossifikationen.

PROBLEM: Currently, non-steroidal anti-inflammatory drugs (NSAID) and radiation have become established as methods of choice in the prevention of ectopic ossifications after total hip replacement. The most effective doses is still not known exact for both. Conventional classification systems only permit a rough distinction of ossifications, so they cannot be used for an exact quantitative measuring. Further, only a limited number of categories can be distinguished. We wanted to find out whether a quantitative measurement of ossifications can be realized, and if small differences in prophylactic effect can be detected in this way. METHOD: By computerized digitized planimetry, we measured ossifications of patients after total hip replacement on plain X-rays of the pelvis. We followed 57 patients for up to 2 years after operation. After marking the ossifications they were measured by drawing the outline with a magnifying glass-mouse. We checked all aspects of precision and reproducibility of the measurements and the comparability with an established classification method (Brooker). RESULTS: The digitized planimetry could be performed on all patients X-rays. It gave a much more differentiated picture compared to the method of Brooker. The method is simple and reproducible, but time consuming. CONCLUSIONS: Digitized planimetry allows a very exact measurement of ectopic bone formation. Compared to conventional classification systems, it differentiates more subtly. In limited, well controlled studies slight differences of prophylactic methods on ossifications can be evaluated. New developments in X-ray technology will make the handling of this method even easier.

Multimodality imaging assessment of meniscal ossicle.

A case of meniscal ossicles occurring in the left knee of a 23-year-old woman is presented. Radiographs showed two calcified lesions at the posteromedial aspect of the knee which were interpreted as loose bodies. Sonography, computed tomography arthrography and magnetic resonance imaging showed the fragments within the posterior horn of the medial meniscus permitting a diagnosis of meniscal ossicles. These techniques can detect meniscal ossicles and exclude intra-articular loose bodies.

A retrospective analysis of high resolution computed tomography in the assessment of cochlear implant patients.

High resolution computed tomography (HRCT) of the temporal bone is performed routinely in the preoperative evaluation for cochlear implantation. The largest multicentre retrospective analysis of data was undertaken to compare the findings on HRCT with the surgical findings in an attempt to determine the accuracy of HRCT. Of the 1009 patients referred, 525 were scanned of whom 335 were implanted. As part of this study we were also able to identify both radiological and non-radiological reasons for rejection of patients for cochlear implantation. the commonest cause being adequate residual hearing. The accuracy of HRCT in predicting cochlear ossification was 94.6%, with a 100% specificity and a 71%, sensitivity. Meningitis was the leading cause of cochlear ossification (44%). We conclude from this extensive multicentre study of both adult and paediatric patients that HRCT is accurate in predicting cochlear abnormality. In post-meningitic patients magnetic resonance imaging (MRI) may be a useful additional investigation.

Cochlear implants in children: what constitutes a complication?

The surgeon must ultimately accept the responsibility for any complications that occur as the result of a cochlear implant. Listening to the cochlear implant team members and responding to their needs may enhance the child's progress. Surgical complications, (i.e., skinflap problems, infection, and facial paralysis) are indeed infrequent, but nonsurgical problems are not. Surgical and nonsurgical experiences were reviewed in 55 children. Ages ranged from 23 months to 18 years at the time of cochlear implantation, which occurred from 1984 to 1995. There were no surgical complications. However, the most common surgical obstacle was ossification, which was present in 40% and undetected by computed tomographic scanning in 16.3% of children. Ossification occurred at the round window and scala tympani in 32.7% and involved the cochlea more extensively in 7.3% of children. In only one child was the cochlea entirely ossified. There were, however, many nonsurgical problems that were viewed as complications in patient management. The single most important complication was device failure. This occurred in 10.9% (5/46) of children with the Cochlear Corporation multichannel implant. Head banging and other temper tantrums, parental interference with rehabilitation, socioeconomic factors, poor compliance by the family unit, equipment problems, educational deficiencies, and impatience with habilitative training were some of the other problems.

Radiological assessment of elongated styloid process and ossified stylohyoid ligament.

In this study a radiological assessment of elongated styloid processes and ossified stylohyoid ligaments was performed on 900 panoramic radiographs of 900 patients. The styloid process(s) were found to be longer than 30 mm in 12 cases; in 8 of these cases elongation was bilateral, and in 4 cases it was unilateral, making a total of 20 elongated processes out of a possible 1800--an incidence of 1.1%. The mean length of the elongated processes was 48.15 mm. Symptoms were present in one case of bilateral elongation.

Three-view radiographic assessment of heterotopic ossification after acetabular fracture surgery.

A random sample of 100 patients who had operative treatment for a fracture of the acetabulum, an otherwise normal appearing hip joint, and at least one year of follow-up were analyzed to assess heterotopic ossification (HO) and its relationship to hip motion. The extent of HO was graded in a blinded fashion according to the Brooker classification, which relies solely on the anteroposterior (AP) view, as well as a modified classification using three radiographic views (AP pelvis, internal, and external Judet oblique views). For each patient, range of motion of the affected hip was compared with that of the contralateral normal limb. There were 16 cases with disagreement between the two methods. As opposed to the Brooker method, the modified classification provided an accurate correlation with the actual hip range of motion.

Quantitative serial assessment of patellofemoral joint osteoarthritis from lateral knee radiographs.

This study describes a new method for patellofemoral joint space measurement on lateral knee radiographs of patients from a case register of knee osteoarthritis (OA). The reproducibility of the technique was tested on 31 lateral radiographs and the validity, accuracy and sensitivity to change were examined in 82 patients (52 female, 30 male, mean age 66.5 years) with anteroposterior and lateral knee radiographs at two time points 3 years apart. The measurements were compared with visual assessments of joint space narrowing, subchondral sclerosis and osteophyte grade previously recorded by an independent observer. The degree of knee flexion was also recorded. The 'narrowest' joint space measurement was found to be a simple reproducible technique (coefficient of variation 8.5%). A significant correlation was found between the measured joint space and knee flexion. The reduction in measured joint space over 3 years was not significant (P = 0.067) but the group contained a large number of disease-free patellofemoral joints. The joint spaces were, however, significantly smaller in the presence of patellofemoral OA with or without tibiofemoral OA suggesting the technique to be valid. The measurements were also significantly smaller in the presence of a visual assessment of joint space narrowing and subchondral sclerosis. The mean measured joint space increased in the presence of severe osteophyte formation. This suggests that patellofemoral joint space measurement from lateral radiographs provides a sensitive and quantitative assessment of progression in OA at this articulation.