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.

Synthetic CT Assessment of Lesions in Children With Rare Musculoskeletal Diseases.

Imaging modalities such as computed tomography (CT) are critical for monitoring musculoskeletal abnormalities in children with rare diseases. However, CT exposes patients to radiation, which limits its utility in the clinical setting, particularly during longitudinal evaluation. Synthetic CT is a novel, noncontrast, and rapid MRI method that can provide CT-like images without any radiation exposure and is easily performed in conjunction with traditional MRI, which detects soft-tissue and bone marrow abnormalities. To date, an evaluation of synthetic CT in pediatric patients with rare musculoskeletal diseases has been lacking. In this case series, the capability of synthetic CT to identify musculoskeletal lesions accurately in 2 rare disease patients is revealed. In Case 1, synthetic CT, in agreement with routine CT, identified an intraosseous lesion in the right femoral neck in a 16-year-old female with fibrous dysplasia, whereas standard-of-care MRIs additionally revealed mild surrounding edema-like bone marrow signal. For Case 2, synthetic CT applied to a 12-year-old female with fibrodysplasia ossificans progressiva revealed heterotopic ossification present along the cervical spine that had caused the fusion of multiple vertebrae. Our evaluation of synthetic CT offers important insights into the feasibility and utility of this methodology in children with rare diseases affecting the musculoskeletal system.

The impact of fibrodysplasia ossificans progressiva (FOP) on patients and their family members: results from an international burden of illness survey.

BACKGROUND: Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare, genetic disorder of heterotopic ossification within soft, connective tissues resulting in limited joint function and severe disability. We present results from an international burden of illness survey (NCT04665323) assessing physical, quality of life (QoL), and economic impacts of FOP on patients and family members. METHODS: Patient associations in 15 countries invited their members to participate; individuals with FOP and their family members were eligible. The survey was available online, in 11 languages, from 18 January-30 April 2021. Participants responded to assessments measuring joint function, QoL, healthcare service and living adaptation utilization, out-of-pocket costs, employment, and travel. RESULTS: The survey received 463 responses (patients, n = 219; family members, n = 244). For patients, decreased joint function was associated with reduced QoL and greater reliance on living adaptations. Nearly half of primary caregivers experienced a mild to moderate impact on their health/psychological wellbeing. Most primary caregivers and patients (≥18 years) reported that FOP impacted their career decisions. CONCLUSIONS: Data from this survey will improve understanding of the impact of FOP on patients and family members, which is important for identifying unmet needs, optimizing care, and improving support for the FOP community.

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.

Assessment of surgical treatment of Eagle's syndrome.

INTRODUCTION: The aim of the study was to assess the effectiveness of surgical treatment of patients with Eagle's syndrome, taking into account both early and late results. MATERIAL AND METHODS: The study group consisted of 15 patients who underwent resection of the styloid process due to Eagle syndrome in the period of 2005-2017. During the follow-up visit, the patients were asked to fill in a post-operative questionnaire that compared the pre-operative symptoms and their severity with the patients' current health condition. The VAS pain scale was used to assess each symptom, and the Laitinen scale was used to assess the quality of life. Data from patients' medical records were also included. The results of the surveys were subjected to statistical analysis. RESULTS: The study showed that in 11 out of 15 cases there was a significant improvement in the level of pain (70.5% on average) and an improvement in quality of life (on average 65%) comparing to the pre-operative condition. The Wilcoxon test for binding pairs, the Mann-Whitney test, the Kruskal-Wallis test and the Spearman correlation coefficient were used in the statistical analysis. There were statistically significant correlations between the recorded improvement rate and the length of the resected styloid process and its setting. DISCUSSION: The study proved that resection of prolonged styloid process from extraoral approach in most cases is an effective method of treatment of Eagle syndrome, that carries low risk of complications.

The Effect of Using Visual Trepan to Treat Single-Segment Ossification of Ligamentum Flavum Under the Endoscope.

OBJECTIVES: To evaluate the surgical outcome of using a trepan to treat single-segment ossification of ligamentum flavum under endoscopy and the clinical value of the new surgical treatment. MATERIALS AND METHODS: Patients who underwent surgery for single-segment ossification of ligamentum flavum from January 2015 to June 2018 were included in a retrospective analysis. Endoscopic visual trepan decompression was performed in 26 patients and posterior spinal canal resection and decompression was performed in 11 patients. Japanese Orthopaedic Association scores, Japanese Orthopaedic Association improvement rate, and visual analog scale scores of both groups were recorded during follow-up. Computed tomography was used to evaluate patients' residual area ratio of the vertebral canal. Operative time, length of stay, amount of bleeding, and hospital cost in both groups were recorded. RESULTS: Average follow-up time was 8.9 ± 2.7 months. Average operative time was 100.6 ± 35.0 minutes in the experimental group and 140.5 ± 28.3 minutes in the control group. At the final follow-up, the average improvement rate of Japanese Orthopaedic Association score was 78.3% in the experimental group and 84.2% in the control group. The average residual area ratio of the vertebral canal, which was <50% before the operation in both groups, recovered to 100% in both groups after the operation. Visual analog scale score of all patients was significantly (P < 0.05) reduced at the final follow-up. CONCLUSIONS: The visual trepan technique using a spinal endoscope can be used to treat single-segment ossification of ligamentum flavum. Advantages include less trauma, faster recovery, and lower cost. However, more cases and long-term follow-up are required to further evaluate the clinical effectiveness and safety of this surgical method.

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.

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).

Longitudinal patient-reported mobility assessment in fibrodysplasia ossificans progressiva (FOP).

BACKGROUND: Fibrodysplasia ossificans progressiva (FOP) is a rare, disabling genetic disorder characterized by episodic soft tissue swelling (flare-ups) that leads to progressive heterotopic ossification and restricted joint mobility. METHODS: Here we present the first longitudinal patient-reported mobility assessment (PRMA) in FOP based on a simple evaluation tool. At initial presentation and follow-up (1-11year span; median: 6 year span), 64 patients (36 females; 28 males) with classic FOP completed a questionnaire designed to rapidly assess mobility at 15 sites (three axial; six upper limb, and six lower limb). In order to validate this instrument, twenty-one of 64 patients (33%) underwent a cumulative analogue joint involvement scale (CAJIS) evaluation by two physicians within six months of their second self-assessment. RESULTS: We found that: 1) mobility changes were episodic and regional, occurring first in the neck and trunk, followed by the upper limbs and finally the lower limbs; 2) interval improvements in mobility did occur, most notably in the lower limbs (18%), and less so in the upper limbs (12%) and trunk (3%), and 3) patient-reported mobility assessments correlate highly (R2=0.81) with physician-reported CAJIS evaluations. CONCLUSION: This is the first longitudinal PRMA in FOP and provides a simple and valid tool that can be used in the design and evaluation of clinical trials in this progressively disabling disease.

Complication Rates for Hip Arthroscopy Are Underestimated: A Population-Based Study.

PURPOSE: To identify major and minor complication rates associated with hip arthroscopy from a payer-based national database and compare with the rates reported in the existing literature. METHODS: Patients who underwent hip arthroscopy between 2007 and 2014 were identified using PearlDiver, a publicly available database. Rates of major and minor complications, as well as conversion to total hip arthroscopy (THA), were determined by using Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision (ICD-9), codes. Incidence rates of select major complications across the entire database were used as a comparison group. Statistical significance was set at P < .05. RESULTS: Of 18 million patients screened from 2007 to 2014, a total of 2,581 hip arthroscopies were identified. The rates of major and minor complications within a 1-year postoperative period were 1.74% and 4.22%, respectively. Complications included heterotopic ossification (2.85%), bursitis (1.23%), proximal femur fracture (1.08%), deep vein thrombosis (0.79%), and hip dislocation (0.58%). The rate of conversion to THA within 1 year was 2.85%. When compared to rates in the general population, the relative risks [RRs] of requiring a THA (age <50 years, RR = 57.66, P < .001; age >50 years, RR = 22.05, P < .001), sustaining a proximal femur fracture (age <50 years, RR = 18.02, P < .001; age >50 years, RR = 2.23, P < .001), or experiencing a hip dislocation (RR 19.60, P < .001) at 1 year after hip arthroscopy were significantly higher in all age groups. CONCLUSIONS: Higher major complication rates after hip arthroscopy were observed using a national payer-based database than previously reported in the literature, especially in regard to hip dislocations and proximal femur fractures. Rates of total hip arthroplasty were similar to prior studies, whereas the rates of revision hip arthroscopy were higher. LEVEL OF EVIDENCE: Level IV, case series.

The Utility of Postoperative Radiographs 2 Years After Primary Total Knee Arthroplasty.

BACKGROUND: Radiographs are routinely used to evaluate patients postoperatively after total knee arthroplasty, but no evidence-based guidelines exist regarding their use. The purpose of this study is to quantify the use of radiographs within 2 years of primary total knee arthroplasty by one surgeon and to determine if routine studies in asymptomatic patients altered patient management. METHODS: Patients undergoing consecutive primary total knee arthroplasties between 2008 and 2010 were identified. Patients undergoing revision or additional simultaneous procedures or those with less than 6 months of radiographic follow-up were excluded. Operative and clinic notes, radiographs, and radiology reports were reviewed. RESULTS: A total of 263 patients were identified; each patient had an average of 13.5 ± 3.8 individual radiographs obtained in 6.5 ± 1.7 series. Twelve radiographic series were noted to have abnormal findings by either the attending surgeon or by radiology report. Three of these patients underwent reoperation directly related to the findings; 2 for deep infections and 1 for extensor mechanism disruption. All 3 patients had reported abnormal symptoms when their films were obtained. The remaining 9 abnormal radiographic findings included focal lucencies or osteolysis, asymmetric spacer wear, a healing stress fracture, an inferior patellar avulsion fracture, and heterotopic ossification. No patient had symptoms attributable to these findings when the radiographs were obtained, and in no case was the management altered based on these finding. CONCLUSION: This study suggests that the observed frequency of routine postoperative radiographs in asymptomatic patients may not be necessary in the first 2 years after primary total knee arthroplasty.

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.

Soft tissue ossification and condylar cartilage degeneration following TMJ disc perforation in a rabbit pilot study.

OBJECTIVE: There are limited clinical treatments for temporomandibular joint (TMJ) pathologies, including degenerative disease, disc perforation and heterotopic ossification (HO). One barrier hindering the development of new therapies is that animal models recapitulating TMJ diseases are poorly established. The objective of this study was to develop an animal model for TMJ cartilage degeneration and disc pathology, including disc perforation and soft tissue HO. METHODS: New Zealand white rabbits (n = 9 rabbits) underwent unilateral TMJ disc perforation surgery and sham surgery on the contralateral side. A 2.5 mm defect was created using a punch biopsy in rabbit TMJ disc. The TMJ condyles and discs were evaluated macroscopically and histologically after 4, 8 and 12 weeks. Condyles were blindly scored by four independent observers using OARSI recommendations for macroscopic and histopathological scoring of osteoarthritis (OA) in rabbit tissues. RESULTS: Histological evidence of TMJ condylar cartilage degeneration was apparent in experimental condyles following disc perforation relative to sham controls after 4 and 8 weeks, including surface fissures and loss of Safranin O staining. At 12 weeks, OARSI scores indicated experimental condylar cartilage erosion into the subchondral bone. Most strikingly, HO occurred within the TMJ disc upon perforation injury in six rabbits after 8 and 12 weeks. CONCLUSION: We report for the first time a rabbit TMJ injury model that demonstrates condylar cartilage degeneration and disc ossification, which is indispensible for testing the efficacy of potential TMJ therapies.

Peripheral organ doses from radiotherapy for heterotopic ossification of non-hip joints: is there a risk for radiation-induced malignancies?

Radiotherapy, used for heterotopic ossification (HO) management, may increase radiation risk to patients. This study aimed to determine the peripheral dose to radiosensitive organs and the associated cancer risks due to radiotherapy of HO in common non-hip joints. A Monte Carlo model of a medical linear accelerator combined with a mathematical phantom representing an average adult patient were employed to simulate radiotherapy for HO with standard AP and PA fields in the regions of shoulder, elbow and knee. Radiation dose to all out-of-field radiosensitive organs defined by the International Commission on Radiological Protection was calculated. Cancer induction risk was estimated using organ-specific risk coefficients. Organ dose change with increased field dimensions was also evaluated. Radiation therapy for HO with a 7 Gy target dose in the sites of shoulder, elbow and knee, resulted in the following equivalent organ dose ranges of 0.85-62 mSv, 0.28-1.6 mSv and 0.04-1.6 mSv, respectively. Respective ranges for cancer risk were 0-5.1, 0-0.6 and 0-1.3 cases per 10(4) persons. Increasing the field size caused an average increase of peripheral doses by 15-20%. Individual organ dose increase depends upon the primary treatment site and the distance between organ of interest and treatment volume. Relatively increased risks of more than 1 case per 10,000 patients were found for skin, breast and thyroid malignancies after treatment in the region of shoulder and for skin cancer following elbow irradiation. The estimated risk for inducing any other malignant disease ranges from negligible to low.