Acute and Stress-related Injuries of Bone and Cartilage: Pertinent Anatomy, Basic Biomechanics, and Imaging Perspective

HT-2 mycotoxin and selenium deficiency: Effects on Femur development and integrity in Young mice

Kashin-Beck Disease (KBD), an osteoarticular disorder, is potentially influenced by several factors, among which selenium deficiency and HT-2 mycotoxin exposure are considered significant. However, the combined effect of these factors on femoral development remains unclear, Conducted over eight weeks on forty-eight male mice categorized into control, selenium-deficient, and HT-2 toxin-exposed groups, including dual-exposure sets, this study comprehensively monitored body weight, bone metabolism markers, and cellular health. Employing biomechanical analysis, micro-computed tomography (micro-CT), and transmission electron microscopy (TEM), we unearthed a reduction in body weight due to HT-2 toxin alone, with selenium deficiency exacerbating these effects synergistically. Our results unveil that both factors independently affect bone metabolism, yet their confluence leads to a pronounced degradation of bone health parameters, including alterations in calcium, phosphorus, and vitamin D levels, alongside marked changes in osteoblast and osteoclast activity and bone cell structures. The notable damage to femoral cortical and trabecular architectures underscores the perilous interplay between dietary selenium absence and HT-2 toxin presence, necessitating a deeper understanding of their separate and joint effects on bone integrity. These discoveries underscore the imperative for a nuanced approach to toxicology research and public health policy, highlighting the pivotal influence of environmental and nutritional factors on skeletal well-being.

Automated quantitative assessment of bone contusions and overlying articular cartilage following anterior cruciate ligament injury

Quantitative methods to characterize bone contusions and associated cartilage injury remain limited. We combined standardized voxelwise normalization and 3D mapping to automate bone contusion segmentation post-anterior cruciate ligament (ACL) injury and evaluate anomalies in articular cartilage overlying bone contusions. Forty-five patients (54% female, 26.4 ± 11.8 days post-injury) with an ACL tear underwent 3T magnetic resonance imaging of their involved and uninvolved knees. A novel method for voxelwise normalization and 3D anatomical mapping was used to automate segmentation, labeling, and localization of bone contusions in the involved knee. The same mapping system was used to identify the associated articular cartilage overlying bone lesions. Mean regional T1ρ was extracted from articular cartilage regions in both the involved and uninvolved knees for quantitative paired analysis against ipsilateral cartilage within the same compartment outside of the localized bone contusion. At least one bone contusion lesion was detected in the involved knee within the femur and/or tibia following ACL injury in 42 participants. Elevated T1ρ (p = 0.033) signal were documented within the articular cartilage overlying the bone contusions resulting from ACL injury. In contrast, the same cartilaginous regions deprojected onto the uninvolved knees showed no ipsilateral differences (p = 0.795). Automated bone contusion segmentation using standardized voxelwise normalization and 3D mapping deprojection identified altered cartilage overlying bone contusions in the setting of knee ACL injury.

Osteochondral Lesions of the Talus: Etiology, Clinical Presentation, Treatment Options, and Outcomes

This article reviews the etiology, clinical presentation, classification schemes, and treatment options for osteochondral lesions of the talus. These lesions typically occur after a traumatic injury and are best diagnosed on MRI. Asymptomatic lesions and incidentally found lesions are best treated conservatively; however, acute displaced osteochondral fragments may require surgical treatment. Lesion characteristics may dictate surgical technique. Outcomes following surgical treatment may be impacted by patient age, BMI, and lesion characteristics.

Investigating cartilage-related diseases by polarization-resolved second harmonic generation (P-SHG) imaging

Establishing quantitative parameters for differentiating between healthy and diseased cartilage tissues by examining collagen fibril degradation patterns facilitates the understanding of tissue characteristics during disease progression. These findings could also complement existing clinical methods used to diagnose cartilage-related diseases. In this study, cartilage samples from normal, osteoarthritis (OA), and rheumatoid arthritis (RA) tissues were prepared and analyzed using polarization-resolved second harmonic generation (P-SHG) imaging and quantitative image texture analysis. The enhanced molecular contrast obtained from this approach is expected to aid in distinguishing between healthy and diseased cartilage tissues. P-SHG image analysis revealed distinct parameters in the cartilage samples, reflecting variations in collagen fibril arrangement and organization across different pathological states. Normal tissues exhibited distinct χ33/χ31 values compared with those of OA and RA, indicating collagen type transition and cartilage erosion with chondrocyte swelling, respectively. Compared with those of normal tissues, OA samples demonstrated a higher degree of linear polarization, suggesting increased tissue birefringence due to the deposition of type-I collagen in the extracellular matrix. The distribution of the planar orientation of collagen fibrils revealed a more directional orientation in the OA samples, associated with increased type-I collagen, while the RA samples exhibited a heterogeneous molecular orientation. This study revealed that the imaging technique, the quantitative analysis of the images, and the derived parameters presented in this study could be used as a reference for disease diagnostics, providing a clear understanding of collagen fibril degradation in cartilage.

Bone bruise vs. non-displaced fracture on MRI: a novel grading system for predicting return-to-play

OBJECTIVE

To devise an MRI grading scheme for osseous contusion patterns in elite hockey players for predicting return-to-play (RTP).

METHODS

A retrospective review was performed to identify traumatic lower extremity osseous injuries in professional hockey players. A total of 28 injuries (17 players) were identified over a 10-year period. All had MRIs acquired at ≥ 1.5 T within a mean interval of 2 days from initial injury. MRIs were retrospectively reviewed by 3 musculoskeletal radiologists for osseous contusion pattern, classified as grade 1 (mild), 2 (moderate), or 3 (severe). Grade 3 contusions were further subdivided by the presence or absence of fracture, defined as discrete cortical disruption on MRI or follow-up CT. RTP was calculated from date of injury to next game played based on game log data. Statistical analysis was performed using ANOVA and post hoc unpaired t test.

RESULTS

Mean RTP for grade 1, 2, and 3 injuries was 2.8, 4.5, and 20.3 days, respectively. Grade 3 injuries without and with cortical fractures had mean RTP of 18.3 and 21.4 days, respectively. ANOVA analysis between groups achieved statistical significance (p < 0.001). Post hoc t test demonstrated statistically significant differences between grade 3 and grades 1 (p < 0.001) and 2 (p < 0.001) injuries. There was no statistical difference in RTP between grade 3 subgroups without and with fracture (p = 0.327).

CONCLUSION

We propose a novel MRI grading system for assessing severity of osseous contusions and predicting RTP. Clinically, there was no statistically significant difference in RTP between severe osseous contusions and nondisplaced fractures in elite hockey players.

Bone Bruise versus Fracture on MRI and the Relevance to Return to Play

We review the spectrum of acute osseous injuries in athletes, ranging from osseous contusion (bone bruise) injuries to nondisplaced cortical fractures. The basic biomechanical concepts, underlying histopathologic changes, and characteristic magnetic resonance imaging (MRI) features of acute osseous injuries are presented. Bone bruise injuries of varying severity are highlighted to showcase the breadth of imaging findings on MRI and methods for characterizing such lesions. We emphasize the importance of accurately assessing patterns of injury on MRI to communicate more effectively with team medical staff and recognize the implications on return to play. This article offers the foundational tools for approaching bone bruise injuries in elite athletes to add value to the diagnosis and treatment of this unique patient population.

SOX family transcription factors as therapeutic targets in wound healing: A comprehensive review

The SOX family plays a vital role in determining the fate of cells and has garnered attention in the fields of cancer research and regenerative medicine. It also shows promise in the study of wound healing, as it actively participates in the healing processes of various tissues such as skin, fractures, tendons, and the cornea. However, our understanding of the mechanisms behind the SOX family's involvement in wound healing is limited compared to its role in cancer. Gaining insight into its role, distribution, interaction with other factors, and modifications in traumatized tissues could provide valuable new knowledge about wound healing. Based on current research, SOX2, SOX7, and SOX9 are the most promising members of the SOX family for future interventions in wound healing. SOX2 and SOX9 promote the renewal of cells, while SOX7 enhances the microvascular environment. The SOX family holds significant potential for advancing wound healing research. This article provides a comprehensive review of the latest research advancements and therapeutic tools related to the SOX family in wound healing, as well as the potential benefits and challenges of targeting the SOX family for wound treatment.

Efficacy of Arthrocentesis and Anterior Repositioning Splints in Treatment of Internal Derangement of TMJ: A Prospective Clinical Study

The aim of this study is to assess the efficacy of double puncture arthrocentesis and anterior repositioning splints in the treatment of internal derangement of temporomandibular joint. 35 patients with mean age of 36.6 years ± 10.2 years diagnosed with unilateral TMD who fell into Wilkes stage 2 and disc displacement with reduction with intermittent locking described by RDC/TMD were treated with Nitzan's double puncture arthrocentesis and were given a anterior repositioning hard splint. The parameters following parameters were assessed at intervals of 1 week, 2 weeks, 1 month, 3 months and 6 months: pain, maximum inter-incisal mouth opening, Joint noise/click. Statistically significant (p < 0.001) improvements were seen at all recorded intervals in all observed parameters. Simultaneous arthrocentesis and anterior repositioning splint therapy is effective in alleviating pain and improving mouth opening without discomfort in patients with unilateral painful TMD showing disc displacement with reduction with intermittent locking.

Transcriptomics reveals the molecular regulation of Chinese medicine formula on improving bone quality in broiler

Skeletal disorder is of concern to the poultry industry as it affects animal welfare and production performance. Traditional Chinese medicine could improve bone quality and reduce the incidence of bone disease, but the molecular regulation of Chinese medicine formula (CMF) on improving bone quality in broilers is still unclear. This study was performed to research the effects of CMF on skeletal performance of Cobb broilers and reveal the molecular regulation. A total of 120 one-day-old Cobb broilers were randomly allocated into 4 equal groups of 30 chickens, with 5 replicates and 6 chickens in each replicate. The control (CON) group was fed a diet without CMF, while the CMF1, CMF2, and CMF3 groups were supplemented with different CMF at 6,000 mg/kg diet, respectively. The broilers were raised to 60 d of age, then bone tissues were collected for biomechanical properties, micro-CT detection and transcriptomic sequencing analysis. The results showed that CMF3 improved the biomechanical properties of broiler tibia, via increasing the elastic modulus (P < 0.05), yield strength (P > 0.05), maximum stress (P < 0.05) and fracture stress (P < 0.05) of the tibia. Micro-CT analysis indicated that CMF3 increased the bone mineral density (BMD), bone volume/total volume (BV/TV), bone surface density (BS/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and decreased the trabecular separation (Tb.Sp) of femur cancellous bone (P < 0.05). RNA-seq analysis revealed 2,177 differentially expressed genes (DEGs) (|log2FoldChange| ≥ 1, FDR < 0.05) between the CMF3 group and CON group. Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) analysis showed 13 pathways mostly associated with bone growth and development and bone metabolism, and we identified 39 bone-related DEGs. This study suggests that CMF3 could improve bone strength and bone microstructure of broilers, and showed a positive effect on bone performance. Our research could provide a theoretical reference for the development of pollution-free feed additives to improve the skeletal performance of broilers, which could help promote healthy farming of chickens.

Subchondral Insufficiency Fractures of the Knee: A Clinical Narrative Review

» Subchondral insufficiency fractures of the knee (SIFKs) are subchondral plate fractures with a prevalence of 2% to 4% of all knee injuries.» Magnetic resonance imaging is the gold standard for evaluating SIFK, while plain radiographs have limited the use in the diagnosis of SIFK.» Among patients with SIFK, 50% to 100% have meniscal pathology.» Medical therapies and standard treatments traditionally used in the management of knee osteoarthritis differ from recommended management of SIFK patients.» Randomized controlled trials and cohort studies with long-term follow-up are needed to determine the optimal rehabilitation protocol, interventional therapy, and prognosis of SIFK patients.

Assessing the Efficacy of Anterior Repositioning Splints in the Management of Temporomandibular Disc Displacement: A Systematic Review and Meta-Analysis

Disc displacement (DD) occurs when the cushioning disc of the temporomandibular joint (TMJ), situated between the jawbone and the skull, is out of position. The condition can be of two kinds: disc displacement with reduction (ddwr) and disc displacement without reduction (ddwor). The present systematic review was undertaken to assess the efficacy of anterior repositioning splints (ARS) for ddwr and ddwor. Three online databases were searched for relevant studies using MeSH keywords and Boolean operators. Initial searches of the databases extracted 552 records. Twelve studies equally representing ARS with ddwr and ddwor were selected. No clear difference could be assessed regarding ARS usage in both conditions. The outcome assessed was the improvement in TMJ symptoms. The results suggested that both ddwr and ddwor were effective in improving temporomandibular joint (TMJ) symptoms in patients who received ARS therapy. Efficacy levels ranged from 71-83% and 50-95% for ARS in ddwr and ddwor, respectively; odds ratio (OR) values ranging from 0.30 and 0.36 were obtained for ARS in both therapies, respectively, indicating similar performance levels. Both ddwr and ddwor respond well to the use of ARS; however, more clinical trials are needed to ascertain and validate the role of ARS as a treatment modality in this regard.

Republication of "Stress Fractures of the Foot and Ankle in Athletes"

Stress fractures of the foot and ankle are common injuries in athletes. Management differs considerably based on fracture location and predisposing factors. Repetitive loading of the foot and ankle in athletes should result in physiologic bone remodeling in accordance with Wolff's law. However, when there is not sufficient time for complete healing to occur before additional loads are incurred, this process can instead lead to stress fracture. Assessment of the athlete's training regimen and overall bone health is paramount to both the discovery and treatment of these injuries, although diagnosis is often delayed in the setting of normal-appearing initial radiographs. While most stress fractures of the foot or ankle can usually be treated nonoperatively with a period of activity modification, fractures in certain locations are considered "high risk" due to poor intrinsic healing and may warrant more proactive operative management.

The Digital Twin: A Potential Solution for the Personalized Diagnosis and Treatment of Musculoskeletal System Diseases

Due to the high prevalence and rates of disability associated with musculoskeletal system diseases, more thorough research into diagnosis, pathogenesis, and treatments is required. One of the key contributors to the emergence of diseases of the musculoskeletal system is thought to be changes in the biomechanics of the human musculoskeletal system. However, there are some defects concerning personal analysis or dynamic responses in current biomechanical research methodologies. Digital twin (DT) was initially an engineering concept that reflected the mirror image of a physical entity. With the application of medical image analysis and artificial intelligence (AI), it entered our lives and showed its potential to be further applied in the medical field. Consequently, we believe that DT can take a step towards personalized healthcare by guiding the design of industrial personalized healthcare systems. In this perspective article, we discuss the limitations of traditional biomechanical methods and the initial exploration of DT in musculoskeletal system diseases. We provide a new opinion that DT could be an effective solution for musculoskeletal system diseases in the future, which will help us analyze the real-time biomechanical properties of the musculoskeletal system and achieve personalized medicine.

[Stress reactions and stress fractures]

Bone stress injuries is an umbrella term that encompasses repetitive microtraumatic events that accumulate to surpass the threshold of bone failure, which can range from bone marrow edema to frank stress fracture as the end point. Due to nonspecific clinical complaints and physical findings, imaging plays a central role in the diagnostic workup of these entities. Magnetic resonance imaging (MRI) is the most important imaging modality with a high sensitivity and specificity and allows for differential diagnosis of other diseases. Edema-sensitive with fat suppression and T1-weighted sequences are the core sequence types, and contrast-enhanced imaging-albeit displaying subtle fractures much more easily-is rarely necessary. Furthermore, MRI enables differentiation of injury severity, which has an impact on length of rehabilitation, therapeutic regimen, and the time to return to sports in athletes.

Bone Marrow Lesions in Athletic Stress Injuries: An Overview

This article discusses the presumed pathophysiology of osseous sport-related stress changes, the optimal imaging strategy for detecting the lesions, and the progression of the lesions as seen on magnetic resonance imaging. It also describes some of the most common stress-related injuries in athletes by anatomical location and introduces some new concepts in the field.

Magnetic Resonance Imaging of Accelerated Bone Remodeling

A regional acceleration of bone remodeling may possibly follow biomechanical insults to the bone. This review assesses the literature and clinical arguments supporting the hypothetical association between accelerated bone remodeling and bone marrow edema (BME)-like signal intensity on magnetic resonance imaging. BME-like signal is defined as a confluent ill-delimited area of bone marrow with a moderate decrease in signal intensity on fat-sensitive sequences and a high signal intensity on fat-suppressed fluid-sensitive sequences. In addition to this confluent pattern, a linear subcortical pattern and a patchy disseminated pattern have also been recognized on fat-suppressed fluid-sensitive sequences. These particular BME-like patterns may remain occult on T1-weighted spin-echo images. We hypothesize that these BME-like patterns, with particular characteristics in terms of distribution and signal, are associated with accelerated bone remodeling. Limitations in recognizing these BME-like patterns are also discussed.

Enzyme-Triggered Crosslinked Hybrid Hydrogels for Bone Tissue Engineering

The quest to develop state-of-the-art hydrogels for bone tissue engineering has accompanied substantial innovation and significant progression in the field of bioactive hydrogels. Still, there is scope for advancement in this cell-friendly and biocompatible scaffold system. The crosslinking approaches used for hydrogel synthesis plays a decisive role in guiding and regulating the mechanical stability, network framework, macroscopic architect, immunological behaviors, and cellular responses. Until recently, enzyme-based crosslinking strategies were considered as the pinnacle in designing efficient hybrid hydrogel systems. A variety of enzymes have been explored for manufacturing hydrogels while taking the advantage of the biocompatible nature, specificity, ability to produce nontoxic by products and high efficiency of enzymes. The current review focuses on the utility of different enzymes as crosslinking agents for hydrogel formation with their application in bone tissue engineering. The field of enzyme crosslinked hydrogel synthesis is rapidly maturing with a lot of opportunities to be explored in bone tissue engineering. Enzyme-based in situ and externally crosslinked hydrogels for bone regeneration is an attractive field, and with innovation in using engineered enzymes this field will continue to flourish with clinical orientation.

Female Athlete Triad Risk Factors Are More Strongly Associated With Trabecular-Rich Versus Cortical-Rich Bone Stress Injuries in Collegiate Athletes

Background:

Bone stress injuries (BSIs) are common in athletes. Risk factors for BSI may differ by skeletal anatomy and relative contribution of trabecular-rich and cortical-rich bone.

Hypothesis:

We hypothesized that Female Athlete Triad (Triad) risk factors would be more strongly associated with BSIs sustained at trabecular-rich versus cortical-rich skeletal sites.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

The study population comprised 321 female National Collegiate Athletic Association Division I athletes participating in 16 sports from 2008 to 2014. Triad risk factors and a Triad cumulative risk score were assessed using responses to preparticipation examination and dual energy x-ray absorptiometry to measure lumbar spine and whole-body bone mineral density (BMD). Sports-related BSIs were diagnosed by a physician and confirmed radiologically. Athletes were grouped into those sustaining a subsequent trabecular-rich BSI, a subsequent cortical-rich BSI, and those without a BSI. Data were analyzed with multinomial logistic regression adjusted for participation in cross-country running versus other sports.

Results:

A total of 19 participants sustained a cortical-rich BSI (6%) and 10 sustained a trabecular-rich BSI (3%) over the course of collegiate sports participation. The Triad cumulative risk score was significantly related to both trabecular-rich and cortical-rich BSI. However, lower BMD and weight were associated with significantly greater risk for trabecular-rich than cortical-rich BSIs. For every value lower than 1 SD, the odds ratios (95% CIs) for trabecular-rich versus cortical-rich BSI were 3.08 (1.25-7.56) for spine BMD; 2.38 (1.22-4.64) for whole-body BMD; and 5.26 (1.48-18.70) for weight. Taller height was a significantly better predictor of cortical-rich than trabecular-rich BSI.

Conclusion:

The Triad cumulative risk score was significantly associated with both trabecular-rich and cortical-rich BSI, but Triad-related risk factors appeared more strongly related to trabecular-rich BSI. In particular, low BMD and low weight were associated with significantly higher increases in the risk of trabecular-rich BSI than cortical-rich BSI. These findings suggest Triad risk factors are more common in athletes sustaining BSI in trabecular-rich than cortical-rich locations.

Lower-extremity fatigue fracture detection and grading based on deep learning models of radiographs

OBJECTIVES

To identify the feasibility of deep learning-based diagnostic models for detecting and assessing lower-extremity fatigue fracture severity on plain radiographs.

METHODS

This retrospective study enrolled 1151 X-ray images (tibiofibula/foot: 682/469) of fatigue fractures and 2842 X-ray images (tibiofibula/foot: 2000/842) without abnormal presentations from two clinical centers. After labeling the lesions, images in a center (tibiofibula/foot: 2539/1180) were allocated at 7:1:2 for model construction, and the remaining images from another center (tibiofibula/foot: 143/131) for external validation. A ResNet-50 and a triplet branch network were adopted to construct diagnostic models for detecting and grading. The performances of detection models were evaluated with sensitivity, specificity, and area under the receiver operating characteristic curve (AUC), while grading models were evaluated with accuracy by confusion matrix. Visual estimations by radiologists were performed for comparisons with models.

RESULTS

For the detection model on tibiofibula, a sensitivity of 95.4%/85.5%, a specificity of 80.1%/77.0%, and an AUC of 0.965/0.877 were achieved in the internal testing/external validation set. The detection model on foot reached a sensitivity of 96.4%/90.8%, a specificity of 76.0%/66.7%, and an AUC of 0.947/0.911. The detection models showed superior performance to the junior radiologist, comparable to the intermediate or senior radiologist. The overall accuracy of the diagnostic model was 78.5%/62.9% for tibiofibula and 74.7%/61.1% for foot in the internal testing/external validation set.

CONCLUSIONS

The deep learning-based models could be applied to the radiological diagnosis of plain radiographs for assisting in the detection and grading of fatigue fractures on tibiofibula and foot.

KEY POINTS

• Fatigue fractures on radiographs are relatively difficult to detect, and apt to be misdiagnosed. • Detection and grading models based on deep learning were constructed on a large cohort of radiographs with lower-extremity fatigue fractures. • The detection model with high sensitivity would help to reduce the misdiagnosis of lower-extremity fatigue fractures.

Cartilage-Inspired Hydrogel with Mechanical Adaptability, Controllable Lubrication, and Inflammation Regulation Abilities

Cartilage is a key component in joints because of its load-bearing and lubricating abilities. However, osteoarthritis often leads to afunction of load-bearing/lubrication and occurrence of inflammation with overexpressed reactive oxygen species (ROS) and nitric oxide (NO). To address these issues, we fabricated a novel polyanionic hydrogel with abundant carboxylates/sulfonates ("CS" hydrogel), inspired by normal cartilage rich in anionic hyaluronate/sulfonate glycosaminoglycan/lubricin, and crosslinked it tightly by Fe3+ ("CS-Fe" hydrogel). The "CS-Fe" hydrogel displayed mechanical adaptability and shear resistance. A low coefficient of friction (∼0.02) appeared when a loose hydrogel layer was generated because of the photoreduction of Fe3+ to Fe2+ by UV irradiation. This biocompatible "CS-Fe" hydrogel suppressed the overexpressed hydroxyl radical (·OH) and NO in macrophages and protected chondrocytes/fibroblasts from aggressive inflammation. Moreover, the layered "CS-Fe" hydrogel avoided cell death of chondrocytes in sliding tests. The results demonstrate that this cartilage-inspired hydrogel is a promising candidate material in cartilage tissue engineering to especially address inflammation.

Bone marrow edema of the medioplantar talar head is associated with severe ligamentous injury in ankle sprain

PURPOSE

To investigate the predictive value of talar head edema (THE) in acute ankle sprain for the presence of concomitant ligament injuries.

METHODS

This retrospective study was approved by the ethics committee and informed consent was obtained. One hundred patients (mean age: 37 years ± 14 [standard deviation], range 13-77 years) with MRI of the ankle after acute trauma were included. The cohort in this matched-pair study consisted of 50 patients with THE (group 1) and 50 patients without THE (group 2). Two readers independently evaluated presence and size of bone marrow edema of the talus head and injuries of the lateral, medial, talonavicular, and spring ligament complex. Statistics included intraclass correlation coefficient (ICC) and Kappa statistics as well as parametric and non-parametric tests.

RESULTS

On average, patients with THE demonstrated significantly more ligament injuries in comparison to patients without THE (3.7 vs. 1.3, p ≤ 0.01). Also, in patients with THE, the number of injured ligaments was significantly higher at the lateral (p = 0.03), medial (p ≤ 0.01), and talonavicular (p ≤ 0.01) compartment in comparison to patients without THE. The most frequently injured ligaments in patients with THE were the anterior talofibular ligament (60%) and the anterior tibiotalar ligament (42%). There was no significant correlation between edema size and the number of injured ligaments or compartments (p = 0.5).

CONCLUSION

THE is associated with more extensive ligamentous ankle injury, in particular to the medial and lateral collateral ligament complex, and therefore indicative of severe ankle trauma.

Subchondral insufficiency fracture of the knee: review of current concepts and radiological differential diagnoses

Subchondral insufficiency fracture of the knee (SIFK) is a common cause of knee joint pain in older adults. SIFK is a type of stress fracture that occurs when repetitive and excessive stress is applied to the subchondral bone. If the fracture does not heal, the lesion develops into osteonecrosis and results in osteochondral collapse, requiring surgical management. Because of these clinical features, SIFK was initially termed "spontaneous osteonecrosis of the knee (SONK)" in the pre-MRI era. SONK is now categorized as an advanced SIFK lesion in the spectrum of this disease, and some authors believe the term "SONK" is a misnomer. MRI plays a significant role in the early diagnosis of SIFK. A subchondral T2 hypointense line of the affected condyle with extended bone marrow edema-like signal intensity are characteristic findings on MRI. The large lesion size and the presence of osteochondral collapse on imaging are associated with an increased risk of osteoarthritis. However, bone marrow edema-like signal intensity and osteochondral collapse alone are not specific to SIFK, and other osteochondral lesions, including avascular necrosis, osteochondral dissecans, and osteoarthritis should be considered. Chondral lesions and meniscal abnormalities, including posterior root tears, are also found in many patients with SIFK, and they are considered to be related to the development of SIFK. We review the clinical and imaging findings, including the anatomy and terminology history of SIFK, as well as its differential diagnoses. Radiologists should be familiar with these imaging features and clinical presentations for appropriate management.

Medial meniscus posterior root repair prevents the progression of subchondral insufficiency fracture of the knee

BACKGROUND

Medial meniscus posterior root tear (MMPRT) causes medial meniscus extrusion (MME) and leads to subchondral insufficiency fracture of the knee (SIFK). However, the progression of SIFK after MMPRT pullout repair remains unknown. This study aimed to investigate the progression of SIFK and compare clinical outcomes in patients with SIFK to those without SIFK after MMPRT pullout repair. We hypothesized that the progression of SIFK would be prevented by MMPRT pullout repair, and clinical outcomes would improve in all patients.

METHODS

The SIFK grade (1-4) was evaluated using T2-fat suppression magnetic resonance imaging. Thirty-eight patients without SIFK (n = 22) and with low-grade SIFK (1 and 2; n = 16) who underwent MMPRT pullout repair were included. Preoperative factors, such as the duration from injury to the time of magnetic resonance imaging/surgery (weeks), femorotibial angle (degree), MME (mm), and clinical outcomes were evaluated, as well as the progression of SIFK.

RESULTS

SIFK was identified in only 9 patients (grade 1) postoperatively. Significantly improved clinical outcomes were observed in all patients. Preoperative femorotibial angle, MME, and duration from injury to the time of magnetic resonance imaging/surgery were 177.1 ± 1.5°, 3.2 ± 1.6 mm, and 6.4 ± 7.0/10.1 ± 7.5 weeks, respectively. No significant difference in preoperative factors and clinical outcomes was observed between patients with SIFK and those without SIFK.

CONCLUSIONS

MMPRT pullout repair prevented the progression of low-grade SIFK and improved clinical outcomes in all patients, although bone contusions (grade 1 SIFK) were not completely healed within 1 year. MMPRT pullout repair could be a good treatment option for optimizing clinical outcomes in patients with low-grade SIFK.

Microindentation Technique to Create Localized Cartilage Microfractures

Articular cartilage is a multiphasic, anisotropic, and heterogeneous material. Although cartilage possesses excellent mechanical and biological properties, it can undergo mechanical damage, resulting in osteoarthritis. Thus, it is important to understand the microscale failure behavior of cartilage in both basic science and clinical contexts. Determining cartilage failure behavior and mechanisms provides insight for improving treatment strategies to delay osteoarthritis initiation or progression and can also enhance the value of cartilage as bioinspiration for material fabrication. To investigate microscale failure behavior, we developed a protocol to initiate fractures by applying a microindentation technique using a well-defined tip geometry that creates localized cracks across a range of loading rates. The protocol includes extracting the tissue from the joint, preparing samples, and microfracture. Various aspects of the experiment, such as loading profile and solvent, can be adjusted to mimic physiological or pathological conditions and thereby further clarify phenomena underlying articular cartilage failure. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Harvesting and dissection of the joint surfaces Basic Protocol 2: Preparation of samples for microindentation and fatigue testing Basic Protocol 3: Microfracture using microindentation Basic Protocol 4: Crack propagation under cyclic loading.

MechAnalyze: An Algorithm for Standardization and Automation of Compression Test Analysis

The mechanical properties of hydrogels, as well as native and engineered tissues are key parameters frequently assessed in biomaterial science and tissue engineering research. However, a lack of standardized methods and user-independent data analysis has impacted the research community for many decades and contributes to poor reproducibility and comparability of datasets, representing a significant issue often neglected in publications. In this study, we provide a software package, MechAnalyze, facilitating the standardized and automated analysis of force-displacement data generated in unconfined compression tests. Using comparative studies of datasets analyzed manually and with MechAnalyze, we demonstrate that the software reliably determines the compressive moduli, failure stress and failure strain of hydrogels, as well as engineered and native tissues, while providing an intuitive user interface that requires minimal user input. MechAnalyze provides a fast and user-independent data analysis method and advances process standardization, reproducibility, and comparability of data for the mechanical characterization of biomaterials as well as native and engineered tissues. Impact statement Mechanical properties of hydrogels are crucial parameters in the development of new materials for tissue engineering. However, manual assessment is tedious, not standardized and suffers under user-to-user bias. Hence, the here presented stand-alone software package provides analysis and statistics of force-displacement and material geometry data to determine the compressive moduli, failure stress, and failure strain in a standardized, robust, and automated fashion. MechAnalyze will substantially support biomechanical testing of hydrogels as well as engineered and native tissues and will thus, be of appreciable value to a broad target group in regenerative medicine, tissue engineering, but also life sciences and biomedicine.

Tuning the Properties of PNIPAm-Based Hydrogel Scaffolds for Cartilage Tissue Engineering

Poly(N-isopropylacrylamide) (PNIPAm) is a three-dimensional (3D) crosslinked polymer that can interact with human cells and play an important role in the development of tissue morphogenesis in both in vitro and in vivo conditions. PNIPAm-based scaffolds possess many desirable structural and physical properties required for tissue regeneration, but insufficient mechanical strength, biocompatibility, and biomimicry for tissue development remain obstacles for their application in tissue engineering. The structural integrity and physical properties of the hydrogels depend on the crosslinks formed between polymer chains during synthesis. A variety of design variables including crosslinker content, the combination of natural and synthetic polymers, and solvent type have been explored over the past decade to develop PNIPAm-based scaffolds with optimized properties suitable for tissue engineering applications. These design parameters have been implemented to provide hydrogel scaffolds with dynamic and spatially patterned cues that mimic the biological environment and guide the required cellular functions for cartilage tissue regeneration. The current advances on tuning the properties of PNIPAm-based scaffolds were searched for on Google Scholar, PubMed, and Web of Science. This review provides a comprehensive overview of the scaffolding properties of PNIPAm-based hydrogels and the effects of synthesis-solvent and crosslinking density on tuning these properties. Finally, the challenges and perspectives of considering these two design variables for developing PNIPAm-based scaffolds are outlined.

3D Printing of Collagen/Oligomeric Proanthocyanidin/Oxidized Hyaluronic Acid Composite Scaffolds for Articular Cartilage Repair

Articular cartilage defects affect millions of people worldwide, including children, adolescents, and adults. Progressive wear and tear of articular cartilage can lead to progressive tissue loss, further exposing the bony ends and leaving them unprotected, which may ultimately cause osteoarthritis (degenerative joint disease). Unlike other self-repairing tissues, cartilage has a low regenerative capacity; once injured, the cartilage is much more difficult to heal. Consequently, developing methods to repair this defect remains a challenge in clinical practice. In recent years, tissue engineering applications have employed the use of three-dimensional (3D) porous scaffolds for growing cells to regenerate damaged cartilage. However, these scaffolds are mainly chemically synthesized polymers or are crosslinked using organic solvents. Utilizing 3D printing technologies to prepare biodegradable natural composite scaffolds could replace chemically synthesized polymers with more natural polymers or low-toxicity crosslinkers. In this study, collagen/oligomeric proanthocyanidin/oxidized hyaluronic acid composite scaffolds showing high biocompatibility and excellent mechanical properties were prepared. The compressive strengths of the scaffolds were between 0.25–0.55 MPa. Cell viability of the 3D scaffolds reached up to 90%, which indicates that they are favorable surfaces for the deposition of apatite. An in vivo test was performed using the Sprague Dawley (SD) rat skull model. Histological images revealed signs of angiogenesis and new bone formation. Therefore, 3D collagen-based scaffolds can be used as potential candidates for articular cartilage repair.

Stress Imaging of Bone

This article defines stress injury, including insufficiency and fatigue fractures. The pathophysiology and risk factors for development of stress injuries are also discussed. The most common locations, including specific imaging examples, are reviewed with an emphasis on early detection and differentiation of high-risk and low-risk locations. Optimal imaging modalities with associated imaging findings are covered, as well as some potential pitfalls to avoid. The importance of correlating imaging findings with symptoms and the prognostic value of imaging grading are also discussed.

Epidemiology of NCAA Bone Stress Injuries: A Comparison of Athletes in Divisions I, II, and III

Background:

Bone stress injuries (BSIs) are a major source of functional impairment in athletes of all sports, with many risk factors, including athlete characteristics and type of sport. In National Collegiate Athletic Association (NCAA) athletics, the stratification of programs into divisions with different characteristics and makeup has been identified as increasing the risk for certain kinds of injuries, but there have been no studies on the difference of BSI rates and characteristics between athletes in Division I (DI) and those in Divisions II and III (DII and DIII).

Purpose/Hypothesis:

To characterize the BSI rates in each division and compare the incidence and characteristics of BSIs within divisions. Our hypothesis was that BSI rates would be higher in DII and DIII athletes as compared with DI athletes.

Study Design:

Descriptive epidemiology study.

Methods:

Five years of recorded BSI data in collegiate athletes via the NCAA Injury Surveillance Program were examined for the academic years 2009-2010 to 2013-2014. BSI rates per 100,000 athlete-exposures (AEs) were compared for DI versus DII and DIII athletes using risk ratios and 95% CIs. Time lost to injury, time of season of injury, and class composition of injured athletes were also compared between divisions.

Results:

Over the 5 years studied, DII and DIII programs reported 252 BSIs more than 1,793,777 AEs (14.05 per 100,000 AEs), and DI programs reported 235 BSIs over 2,022,592 AEs (11.62 per 100,000 AEs). The risk ratio was significant for D1 versus DII and DIII (1.21; 95% CI, 1.01-1.44). There was a significant difference in time lost to injury in DI versus DII and DIII, χ²(5, n = 449) = 16.54; P = .006. When data were stratified by individual sport, there were no significant divisional differences in high-risk sports.

Conclusion:

In the current study, NCAA DII and DIII athletes had higher rates of BSI than their DI counterparts. As compared with DII and DIII athletes, the DI athletes had a significantly greater proportion of BSIs that did not result in absence from participation in sport.

A Stretchable Scaffold with Electrochemical Sensing for 3D Culture, Mechanical Loading, and Real-Time Monitoring of Cells

In the field of three-dimensional (3D) cell culture and tissue engineering, great advance focusing on functionalized materials and desirable culture systems has been made to mimic the natural environment of cells in vivo. Mechanical loading is one of the critical factors that affect cell/tissue behaviors and metabolic activities, but the reported models or detection methods offer little direct and real-time information about mechanically induced cell responses. Herein, for the first time, a stretchable and multifunctional platform integrating 3D cell culture, mechanical loading, and electrochemical sensing is developed by immobilization of biomimetic peptide linked gold nanotubes on porous and elastic polydimethylsiloxane. The 3D scaffold demonstrates very good compatibility, excellent stretchability, and stable electrochemical sensing performance. This allows mimicking the articular cartilage and investigating its mechanotransduction by 3D culture, mechanical stretching of chondrocytes, and synchronously real-time monitoring of stretch-induced signaling molecules. The results disclose a previously unclear mechanotransduction pathway in chondrocytes that mechanical loading can rapidly activate nitric oxide signaling within seconds. This indicates the promising potential of the stretchable 3D sensing in exploring the mechanotransduction in 3D cellular systems and engineered tissues.

Bilayered, peptide-biofunctionalized hydrogels for in vivo osteochondral tissue repair

Osteochondral defects present a unique clinical challenge due to their combination of phenotypically distinct cartilage and bone, which require specific, stratified biochemical cues for tissue regeneration. Furthermore, the articular cartilage exhibits significantly worse regeneration than bone due to its largely acellular and avascular nature, prompting significant demand for regenerative therapies. To address these clinical challenges, we have developed a bilayered, modular hydrogel system that enables the click functionalization of cartilage- and bone-specific biochemical cues to each layer. In this system, the crosslinker poly(glycolic acid)-poly(ethylene glycol)-poly(glycolic acid)-di(but-2-yne-1,4-dithiol) (PdBT) was click conjugated with either a cartilage- or bone-specific peptide sequence of interest, and then mixed with a suspension of thermoresponsive polymer and mesenchymal stem cells (MSCs) to generate tissue-specific, cell-encapsulated hydrogel layers targeting the cartilage or bone. We implanted bilayered hydrogels in rabbit femoral condyle defects and investigated the effects of tissue-specific peptide presentation and cell encapsulation on osteochondral tissue repair. After 12 weeks implantation, hydrogels with a chondrogenic peptide sequence produced higher histological measures of overall defect filling, cartilage surface regularity, glycosaminoglycan (GAG)/cell content of neocartilage and adjacent cartilage, and bone filling and bonding compared to non-chondrogenic hydrogels. Furthermore, MSC encapsulation promoted greater histological measures of overall defect filling, cartilage thickness, GAG/cell content of neocartilage, and bone filling. Our results establish the utility of this click functionalized hydrogel system for in vivo repair of the osteochondral unit. STATEMENT OF SIGNIFICANCE: Osteochondral repair requires mimicry of both cartilage- and bone-specific biochemical cues, which are highly distinct. While traditional constructs for osteochondral repair have mimicked gross compositional differences between the cartilage and bone in mineral content, mechanical properties, proteins, or cell types, few constructs have recapitulated the specific biochemical cues responsible for the differential development of cartilage and bone. In this study, click biofunctionalized, bilayered hydrogels produced stratified presentation of developmentally inspired peptide sequences for chondrogenesis and osteogenesis. This work represents, to the authors' knowledge, the first application of bioconjugation chemistry for the simultaneous repair of bone and cartilage tissue. The conjugation of tissue-specific peptide sequences successfully promoted development of both cartilage and bone tissues in vivo.

An Overview of Anterior Repositioning Splint Therapy for Disc Displacement-related Temporomandibular Disorders

Anterior repositioning splint (ARS) therapy is considered one of the most effective therapies for treating disc displacement-related temporomandibular disorders (TMDs), which account for a large proportion of TMD cases. Owing to the wide application of this therapy, the exact mechanism of remission has increasingly drawn attention. Given that practitioners have different views on ARS therapy, its indications are broadened, and operating methods diverged. This review attempts to provide an overview of ARS therapy and helps practitioners establish indications and suitable operating methods. Representative views in the past 10 years were summarised, and conclusions were drawn as follows: The mechanism of ARS therapy is mainly attributed to internal derangement correction, improvement of stress distribution and recently reported joint remodeling. It has an evident effect in the short term, and the most prevalent operating methods are protruding the mandible to the edge-to-edge position and wearing the ARS for 24 hours daily for 3-6 months. However, long-term stability is not optimal, and thus indications should be selected carefully. Notably, most of the clinical studies in this field are case analyses with low-quality evidence. Well-designed RCTs are required to further validate relevant theories.

Visualization of the epimysium and fascia thoracolumbalis at the lumbar spine using MRI

BACKGROUND

The fascia thoracolumbalis (FTL) is an important component for stabilization and motion control of the lumbar spine. It coordinates the traction forces of the autochthonous muscles of the back (AM) and connects them to the muscles of the abdominal wall, shoulder, and buttocks.

OBJECTIVES

The aim of our study was to describe the assessment of the normal FTL and epimysium of the AM in MRI and to identify patterns associated with pathological changes in the lumbar spine.

MATERIAL AND METHODS

A total of 33 patients were retrospectively evaluated: 15 patients had no pathology at the lumbar spine; six patients had previous hemilaminectomy, three had spondylodesis, two had ventrolisthesis, and seven had scoliosis. The thickness of the FTL and EM was measured, and the adhesion of both structures was assessed.

RESULTS

The fascial thickness at the levels of the lumbar vertebral bodies LVB 3 was 1.8, of LVB 4 it was 2.0, of LVB 5 it was 2.1, and at the sacral vertebra SVB 1 it was 1.8 mm. Fascial adhesions together with thickening of the EM occurred at the level of LVB 4 in 36% of the cases independently of the underlying disorder. Only thickening of the EM was seen in 48% of cases at the level of SVB 1. By contrast, adhesion of the FTL without epimysial changes occurred in 36% of cases at the level of LVB 3.

CONCLUSION

Thickening and adhesions at the EM and FTL occurred both postoperatively and in the case of scoliosis. Furthermore, lipomatous and muscular herniation could be detected in the FTL postoperatively. Epimysial and fascial alterations may be imaging manifestations of chronic myofascial back pain and should be included in radiological assessments.

Subchondroplasty for Bone Marrow Lesions in the Arthritic Knee Results in Pain Relief and Improvement in Function

Subchondroplasty is a relatively new joint preserving procedure, which involves the localized injection of calcium pyrophosphate bone substitute into the bone marrow lesion. The advent of magnetic resonance imaging (MRI) has greatly facilitated the identification of these bone marrow lesions. We investigated the clinical efficacy of subchondroplasty in the treatment of symptomatic bone marrow lesions in the knee, including knees with preexisting osteoarthritis. This study comprised of 12 patients whose knees were evaluated with standard radiographs and MRI to identify and localize the bone marrow lesions. They then underwent subchondroplasty under intraoperative radiographic guidance. Preoperative and postoperative visual analog scale (VAS) pain scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, and Knee Injury and Arthritis Outcome Scores (KOOS) were obtained. VAS scores improved significantly from 7.5 ± 1.8 before surgery to 5.2 ± 2.7 after surgery. This further improved to 2.1 ± 2.4 at the one-year follow-up. KOOS scores improved significantly from 38.5 ± 17.0 before surgery to 73.2 ± 19.0 at the one-year follow-up. WOMAC scores improved significantly from 47.8 ± 20.5 before surgery to 14.3 ± 13.2 at the one-year follow-up. Subchondroplasty offers an effective way to treat subchondral bone marrow lesions in the arthritic knee, resulting in improvement in symptoms and early return to activity. Long-term studies are required to evaluate if these benefits can last. This is a Level II study.

Sports injuries at the Rio de Janeiro 2016 Summer Paralympic Games: use of diagnostic imaging services

OBJECTIVE

To describe the occurrence of imaging-depicted sports-related injuries (bone, muscle, tendon, and ligament injuries) during the Rio 2016 Summer Paralympic Games.

METHODS

Descriptive data on all imaging examinations by using radiography, ultrasonography (US), and MRI were collected and retrospectively analyzed centrally by five musculoskeletal radiologists according to imaging modality, country of origin of the athletes, type of sport, type of disability, and type and location of injury.

RESULTS

We report 109 injuries in 4378 athletes. A total of 382 radiologic examinations were performed in 261 athletes, including 118 (31%) radiographic, 22 (6%) US, and 242 (63%) MRI examinations. Para athletes from Africa had the highest utilization rate (20.1%, 67 out of 333). Athletes from Europe underwent the most examinations with 29 radiographic, 12 US, and 66 MRI examinations. The highest utilization rate of imaging modalities by sport was among Judo para athletes (16.7%, 22 out of 132). Most injuries were reported in athletics discipline (37.6%, 41 out of 109). Most injuries were also reported among para athletes with visual impairment (40 injuries, 36.7% of all injuries). Bone stress injuries were most common among para athletes with visual impairment (6 out of 7). Para athletes with visual impairment were also more prone to bone stress injuries than traumatic fractures, unlike para athletes with neurologic and musculoskeletal impairments.

CONCLUSIONS

Imaging was used in 6.0% of para athletes. MRI comprised 63% of imaging utilization. Identification of patterns of injuries may help building future prevention programs in elite para athletes.

KEY POINTS

• The highest imaging utilization rates were found among para athletes competing in Judo, sitting volleyball, powerlifting, and football. • Utilization of diagnostic imaging at the Rio 2016 Paralympic Games demonstrated similar trends to what was observed at the Rio 2016 Olympic Games. • Comparison of the rate of imaging-depicted injuries between Olympic and Paralympic athletes is limited due to inherent differences between the two athlete populations and the manner in which injury risk in the Paralympic athlete varies dependent on impairment type, which is not the case for the Olympic athlete.

Lateral femoral condyle insufficiency fractures: imaging findings, demographics, and analysis of outcomes

OBJECTIVE

To describe imaging characteristics and demographics of lateral femoral condyle insufficiency fractures (LFCIFs) and identify characteristics associated with progression to epiphyseal collapse.

MATERIALS AND METHODS

A retrospective review of 105 consecutive patients with LFCIF was performed (mean age 58.1 years) after excluding post-traumatic and pathological fractures. Lesion size and location, presence of bone marrow edema-like signal, soft tissue edema, chondrosis grade, and meniscus pathology were documented. Demographics were recorded from the electronic patient record. Follow-up MRI and/or radiographs were evaluated for healing/stability or progression to epiphyseal collapse. Bone mineral density was assessed from dual-energy x-ray absorptiometry (DEXA) scans and/or radiographs.

RESULTS

Fifty-six female and 49 male subjects were included. Female subjects were older at presentation (60.5 versus 56.3 years, p = .02). A total of 61.7% of the subjects with available DEXA and/or radiographs had osteopenia/osteoporosis. The central weight-bearing (61%) and outer condyle (54.3%) were most involved. High-grade chondrosis was present in ≥ 1 compartment in 70.5% including 42% in the lateral compartment. A total of 67.6% had ≥ 1 meniscus tear with similar frequency of medial and lateral tears (47.6% versus 41%). Bone marrow edema-like signal was present in all cases; soft tissue edema was present in 83.8%. Fifty-three subjects had available follow-up MRI (n = 24) and/or radiographs (n = 29). Increased age, fracture dimensions, presence of medial meniscus tears, and high-grade patellofemoral chondrosis were associated with progression (p ≤ .05).

CONCLUSION

LFCIFs are associated with meniscus tears, high-grade chondrosis, and osteopenia/osteoporosis with more global knee pathology present when compared with medial femoral condyle insufficiency fracture. Increased age, medial meniscus tears, fracture dimensions, and high-grade patellofemoral chondrosis were associated with progression.

Magnetic resonance imaging of the ankle and foot

This article reviews the magnetic resonance imaging (MRI) findings of the normal anatomy and various pathologic conditions of the ankle and foot commonly encountered in clinical practice. The spectrum of entities discussed includes osseous and osteochondral injuries, ligamentous injuries, common traumatic and degenerative tendon pathology, abnormalities of transverse tarsal joint (Chopart) and tarsometatarsal joint (Lisfranc) complexes, pathological conditions affecting capsuloligamentous structures of the great toe and lesser toes, as well as pedal infection, with a focus on diabetic osteomyelitis and neuropathic osteoarthropathy.

Dual-energy CT in musculoskeletal trauma

Dual-energy computed tomography (DECT) combines the advantages of conventional CT with the ability to detect bone marrow oedema (BMO), which was previously limited to magnetic resonance imaging (MRI). By analysing DECT virtual non-calcium (VNCa) maps, radiologists can improve the detection of subtle and occult fractures and approximate the acuity/healing of fractures of indeterminate age. This review highlights the role of DECT in the assessment of musculoskeletal trauma, particularly among elderly, post-menopausal women and those at risk for osteoporosis. DECT is especially useful in investigating trabecular bone predominant regions (e.g., vertebral bodies, pelvis, hip, and long bone metaphyses) for stress (i.e., fatigue or insufficiency) and fragility fractures. CT is often performed first due to its increased availability, especially in the emergency setting, shorter imaging duration, and possible patient contraindications to magnetic resonance imaging (MRI). By enabling BMO detection, DECT may have a role in triaging patients for definitive MRI assessment. Understanding the role of anatomical, pathological, and patient factors in image interpretation can improve radiologist adoption of DECT, increase diagnostic confidence, and improve patient management.

Prevalence of Undiagnosed Subchondral Insufficiency Fractures of the Knee in Middle Age Adults with Knee Pain and Suspected Meniscal Tear

Objective

Symptomatic knee osteoarthritis (OA) and meniscal tear are often treated with weight-bearing exercises and without ordering advanced imaging (e.g. MRI). This may lead to missed diagnoses of subchondral insufficiency fracture of the knee (SIFK). Failure to diagnose SIFK has treatment implications, as patients with SIFK are typically managed with a period of reduced weight-bearing. The primary objective of this study is to determine the prevalence of undiagnosed SIFK among persons treated non-operatively for knee pain and suspected meniscal tear(s).

Methods

The randomized controlled trial, TeMPO (Treatment of Meniscal Problems and Osteoarthritis), enrolls subjects whose clinicians suspect concomitant meniscal tear and knee OA. TeMPO participants undergo MRI ordered by the study to confirm meniscal tear. All study-ordered MRIs revealing a fracture were reviewed by two study radiologists who noted features of the fracture and joint. We report prevalence of SIFK and clinical and imaging features on these subjects with 95% confidence intervals.

Results

Ten of the 340 study-ordered MRIs had SIFK, resulting in an estimated prevalence of 2.94% (95% CI: 1.15%, 4.71%). Eight of the ten participants with SIFK had fractures located medially. The femur was involved in five of these participants, tibia in four, and both in one. Five of the ten participants did not have meniscal tears.

Conclusions

This is the only reported estimate of undiagnosed SIFK in adults with knee pain, to our knowledge. Approximately 3% of patients managed with weight-bearing exercise for suspected meniscal tear may have SIFK, a diagnosis typically treated with reduced weight-bearing approaches.

Integrated 3D Information for Custom-Made Bone Grafts: Focus on Biphasic Calcium Phosphate Bone Substitute Biomaterials

Purpose: Several studies showed that the sintering temperature of 1250 °C could affect the formation of α-Ca₃(PO₄)₂, which is responsible for the reduction of the hardness value of biphasic calcium phosphate biocomposites, but they did not evaluate the inference of the sintering time at peak temperature on transition of β-Ca₃(PO₄)₂ to α-Ca₃(PO₄)₂. This analysis explored, in an innovative way, inferences and correlations between volumetric microstructure, mechanical properties, sintering temperature, and time at peak temperature in order to find the best sintering conditions for biphasic calcium phosphate composites grafted in severe alveolar bone defects. Methods: Sintered biphasic calcium phosphates (30%-hydroxyapatite/70%-tricalcium phosphate) were tested by microCT imaging for the 3D morphometric analysis, by compressive loading to find their mechanical parameters, and by X-ray diffraction to quantify the phases via Rietveld refinement for different sintering temperatures and times at the peak temperature. Data were analysed in terms of statistical inference using Pearson’s correlation coefficients. Results: All the studied scaffolds closely mimicked the alveolar organization of the jawbone, independently on the sintering temperatures and times; however, mechanical testing revealed that the group with peak temperature, which lasted for 2 hours at 1250 °C, showed the highest strength both at the ultimate point and at fracture point. Conclusion: The good mechanical performances of the group with peak temperature, which lasted for 2 hours at 1250 °C, is most likely due to the absence of the α-Ca₃(PO₄)₂ phase, as revealed by X-ray diffraction. However, we detected its presence after sintering at the same peak temperature for longer times, showing the time-dependence, combined with the temperature-dependence, of the β-Ca₃(PO₄)₂ to α-Ca₃(PO₄)₂ transition.

Comparison of 8-year knee osteoarthritis progression in 2 siblings: a case-based review

Because the pathophysiology of knee osteoarthritis is poorly understood, optimal evidence-based clinical management is uncertain. Sibling comparison studies can help inform a clinical model to guide preventive care. We compared the 8-year clinical outcomes in 2 sisters with a family history of osteoarthritis, normal BMI, and absence of knee pain at baseline. Both patients had Kellgren–Lawrence grade 1 in the affected knee at the time of twisting knee injuries leading to osteoarthritis diagnoses at age 50 (patient 1) and 51 (patient 2). Patient 1 developed a chronic right knee effusion, and progressed to Kellgren–Lawrence grade 3 bilaterally by the time she had a right total knee replacement at age 58. Patient 2 had subchondral fractures of the right knee with transient effusion, which healed after 1 year of partial weight-bearing with crutches and subsequent daily use of knee sleeves. Patient 2 had Kellgren–Lawrence grade 0 bilaterally upon surveillance imaging at age 58. The terms “osteoarthritis and knee and diagnostic imaging and subchondral bone and pathophysiology” were searched in the PubMed database to identify original research articles to inform a clinical model consistent with the patients’ outcomes. A fluid model of osteoarthritis was the best explanatory model for the discordant clinical trajectories of the age-matched siblings. Patient recommendations are presented based on these findings.

Glossary of terms for musculoskeletal radiology

Members of the International Skeletal Society compiled a glossary of terms for musculoskeletal radiology. The authors also represent national radiology or pathology societies in Asia, Australia, Europe, and the USA. We provide brief descriptions of musculoskeletal structures, disease processes, and syndromes and address their imaging features. Given the abundance of musculoskeletal disorders and derangements, we chose to omit most terms relating to neoplasm, spine, intervention, and pediatrics. Consensus agreement was obtained from 19 musculoskeletal radiology societies worldwide.

Subchondral insufficiency fracture of the knee: grading, risk factors, and outcome

OBJECTIVE

To propose an magnetic resonance imaging (MRI) grading system for subchondral insufficiency fracture of the knee (SIFK) to predict outcome and assess risk factors.

MATERIALS AND METHODS

A total of 50 SIFK patients were retrospectively reviewed utilizing two MRI examinations approximately a year apart and compared them with 51 control subjects. A grading system was introduced that classifies lesions as low- vs high-grade. Lesion location 3D dimensions, extent of bone marrow edema (BME), location of meniscal tears and associated extrusion, degree of chondrosis and among other parameters were stratified according to lesion grade and compared with follow-up examinations. Statistical analyses were performed (Pearson's correlation, binary logistic regression, and Chi-squared analysis).

RESULTS

The majority of SIFK lesions were low-grade (LG; 78%) and most of them (70%) were observed in the medial femoral condyle. Predictor variables comparing low-grade and high-grade SIFK lesions included meniscal tear (p = 0.01), degree of extrusion (p < 0.003), chondrosis (p = 0.01), medial chondrosis grade (p = 0.001), medial femoral condyle (p = 0.01), surface collapse (p < 0.0001), marrow edema improvement (p < 0.0001), first MRI anteroposterior dimension (p = 0.001), transverse dimension (p < 0.001), and ellipsoid volume (p = 0.02). Predictor variables found to be significantly different between controls and patients were meniscal tear (p = 0.024), location of the medial meniscal tear (p < 0.0001), degree of extrusion (p < 0.0001), chondrosis (p < 0.0001), joint effusion (p < 0.0001), Baker's cyst (p < 0.0001), knee lock (p = 0.03) and buckle (p = 0.01), and history of trauma (p = 0.01).

CONCLUSION

A SIFK grading system for MRI is introduced. Surrogate markers of high-grade lesions include medial meniscus posterior root tears with associated moderate to severe extrusion, high-grade chondrosis, larger lesion sizes (anteroposterior/transverse), and articular surface collapse. Improvement of BME on follow-up was highly predictive of low-grade disease.

Value of CT to detect radiographically occult injuries of the proximal femur in elderly patients after low-energy trauma: determination of non-inferiority margins of CT in comparison with MRI

PURPOSE

To determine the margins of non-inferiority of the sensitivity of CT and the sample size needed to test the non-inferiority of CT in comparison with MRI.

MATERIALS AND METHODS

During a 2-year period, elderly patients with suspected radiographically occult post-traumatic bone injuries were investigated by CT and MRI in two institutions. Four radiologists analyzed separately the CT and MRI examinations to detect post-traumatic femoral injuries. Their sensitivities at CT (SeCT) and MRI (SeMRI) were calculated with the reference being a best valuable comparator (consensus reading of the MRI and clinical follow-up). ROC analysis followed by an exact test (Newcombe's approach) was performed to assess the 95% confidence interval (CI) for the difference SeCT-SeMRI for each reader. A sample size calculation was performed based on our observed results by using a one-sided McNemar's test.

RESULTS

Twenty-nine out of 102 study participants had a post-traumatic femoral injury. SeCT ranged between 83 and 93% and SeMRI ranged between 97 and 100%. The 95% CIs for (SeCT-SeMRI) were [- 5.3%, + 0.8%], (p^R1 = 0.1250), [- 4.5%; + 1.2%] (p^R2 = 0.2188), [- 3.4%; + 1.1%] (p^R3 = 0.2500) to [- 3.8%; + 1.6%] (p^R4 = 0.3750) according to readers, with a lowest limit for 95% CIs superior to a non-inferiority margin of (- 6%) for all readers. A population of 440 patients should be analyzed to test the non-inferiority of CT in comparison with MRI.

CONCLUSION

CT and MRI are sensitive for the detection of radiographically occult femoral fractures in elderly patients after low-energy trauma. The choice between both these modalities is a compromise between the most available and the most sensitive technique.

KEY POINTS

• The sensitivity of four separate readers to detect radiographically occult post-traumatic femoral injuries in elderly patients after low-energy trauma ranged between 83 and 93% at CT and between 97 and 100% at MRI according to a best valuable comparator including MRI and clinical follow-up. • CT is a valuable alternative method to MRI for the detection of post-traumatic femoral injuries in elderlies after low-energy trauma if a 6% loss in sensitivity can be accepted in comparison with MRI. • The choice between CT and MRI is a compromise between the most available and the most sensitive technique.

Pitfalls in Pediatric Trauma and Microtrauma

Fractures are common in children, although accurate diagnosis is confounded by mimics of fractures some of which are unique to the pediatric population. Such fracture mimics include developmental variations of the growth plates, normal anatomic structures that simulate fracture lines, and/or metabolic disorders that alter the pattern of ossification. Although subtle clues on plain radiographs may help to discriminate between a true fracture or injury and a fracture mimic, MR imaging may be helpful to eliminate uncertainty or expedite diagnosis.