Many have long thought that the means of assessing osteoarthritis in the knee are less than ideal.
Although conventional X-ray radiographs are widely considered as gold standard for the assesssment of knee OA, in clinical and scientific settings they increasingly bare significant limitations in situations where high resolution and detailed assessment of cartilage is demanded. – Wick et al, Gereontology. 2014; 60(5).
Current standard of care consists of a series of X-rays on a routine interval basis to assess whether disease is progressing further and corresponding with the patient’s symptoms. There is questionable reliability of joint space width (JSW) measurements from X-ray, and it is difficult to decipher whether there has been a significant change in anatomy to explain the patient’s worsening symptoms.
Watch the video to see a bilateral weight bearing CT dataset of a patient with osteoarthritis in his knees.
CurveBeam’s cone beam CT technology offers high resolution, axial, coronal, and sagittal views in 0.3mm slices generated from a 30 second scan. This provides 3-dimensional, weight bearing information with radiation exposure levels almost equivalent to the standard series of knee X-rays. The 30 second scan is much faster for the technician to acquire compared to the back and forth for multiple views in an X-ray series.
Incorporating weight bearing CT technology into daily practice could facilitate complete visualization of the joint surface in axial slices and take into consideration the effects of weight bearing at the joint line. In time, clinicians should be able to provide more detailed information on location and progression of disease for their patients, and therefore, determine the best course of care moving forward.
In this episode of the CurveBeam podcast, host Vinti Singh sat down with Dr. Martinus Richter, MD, Ph.D.to discuss the results of his latest published study: “Results of more than 11,000 scans with weight-bearing CT – Impact on costs, radiation exposure and procedure time.” This first-of-its-kind study examined the economic implications of CT scans versus radiographs for patients.
Click here to download the execuctive summary for this episode of CurveBeam Connect, featuring Dr. Martinus Richter, MD, PhD.
Dr. Richter is department head of the foot and ankle orthopedic surgery section at Hospital Rummelsberg in Rummelsberg, Germany and has published numerous studies in orthopedic journals.
Dr. Richter oversaw a study, which was conducted over more than five years. to assess the benefits of using weight bearing CT (WBCT) instead of a combination of weight bearing radiographs (R) and conventional CT (CT). The study looked at the modalities’ impacts on costs, radiation exposure and procedure time.
In the study, 11,009 scans, taken from July 2013 through March of 2019, were obtained from 4987 patients—45% (4,897) before treatment; 55% (6,022) at follow-up—with a yearly average of 1,957 WBCTs (bilateral scans). These were compared to 1,850 Rs (bilateral feet, dorsoplantar and lateral, metatarsal head skyline view) and 254 CTs obtained from 885 patients (RCT group) in 2012.
The conclusions help to solidify that not only can WBCT more precisely measure bone position than conventional R and CT scans, but also decreases the time needed for image acquisition by 77% and radiation dosage by 10%, while increasing institution financial profitability by $57.19 (51€) per patient.
CT assessment of patients casted for a non-displaced scaphoid fracture shows union occurring at approximately 7.5 weeks, with a majority of fractures healing in less than 6 weeks, according to a 2016 study by Ruby Grewal et al. Similar studies using plain X-Ray demonstrated union time to be anywhere between 10 – 24 weeks. The authors noted the union time on CT may even be overestimated because the majority of patients’ first CT scan after casting was not until 6 weeks.
In a previous study, Professor Timothy Davis wrote CT studies demonstrate healing of a non-displaced fracture treated with a plaster cast can occur in as little as 4 weeks. If a fracture is displaced less than 2 mm, Davis said those CT studies suggest a plaster cast for 8 – 12 weeks.
CT is ideally performed for all scaphoid waist fractures in the first week after injury to classify whether they are displaced or non-displaced, said Professor Davis, an orthopedic surgeon at Woodthorpe Hospital in Nottingham, UK said in his research paper.
By using CT as a baseline, researchers at the Roth/McFarlane Hand and Upper Limb Center in London said they were able to identify fractures which may have appeared non-displaced on X-Ray, but were actually minimally displaced.
“We feel that the added visualization of CT over plain radiography enables the surgeon to properly select which fractures are appropriate for non-operative cast treatment with an expected high degree of union,” the researchers said in a study published in The Open Orthopaedics Journal.
Out of the research setting, routine CT scans of scaphoid fractures may not be practically feasible, Professor Davis wrote.
“I appreciate that [routine CT assessment of scaphoid fractures] is impossible in many centers at the present time but it should become increasingly possible in the future,” Professor Davis wrote in the medical journal “Annals of the Royal College of Surgeons of England” in 2013.
The InReach is a compact CT imaging system dedicated to the hand, wrist and elbow. The system received FDA and CE approval in 2017. Since then, it has been installed in leading orthopedic centers and hospitals in the United States. The InReach allows orthopedic practices to offer CT imaging at the point-of-care.
“InReach has been an excellent asset allowing in-office imaging and rapid CT evaluation of the hands with complex diagnostic dilemmas,” said Dr. Lloyd Champagne, an orthopedic surgeon at the Arizona Center for Hand to Shoulder Surgery in Phoenix.
Fifteen percent of acute fractures of the scaphoid waist fail to unite if treated non-operatively in plaster, resulting in a persistent loss of function, according to the 2013 article. Plain X-Rays do not clearly show fracture features such as displacement and communition. Previous inter-observer studies have shown radiographs of scaphoid fractures are neither sensitive nor specific.
For professional athletes, injuries mean reduced playing time, impacted performance, and, in rare cases, an end to their careers. These injuries often affect the lower extremities, primarily because their sports require high-risk activities like jumping, cutting movements, and collision with other players. While traditional scanning techniques have mainly been used to identify injuries, a recent study found that weight-bearing cone beam computed tomography (CBCT) may be crucial to not only identify anatomic risks but also to help develop treatments explicitly tailored to the needs of professional athletes.
Incorporating new tech
In The Orthopaedic Journal of Sports Medicine, Dr. Cesar de Cesar Netto, et al. examined the morphology of foot injuries in 45 active NBA players. The doctors used weight-bearing CBCT scans to obtain 3D imaging of each foot. These scans provide more accurate alignment measurements than traditional scans and offer views of the foot while the player’s natural weight is being placed on it.
The study sought to discern whether the morphology of NBA players differed from that of the population at large, and whether the morphology changed based on position played. Foot and ankle injuries account for 27 percent of professional sports injuries, and 85 percent of basketball players experience at least one ankle sprain in their career.
Getting a better look
The players who participated in the study ranged from 20 to 31 years of age, and in total 29 right feet and 25 left feet were studied. All images were taken using a state-of-the-art pedCAT CurveBeam pedCAT system to obtain reliable and accurate images of each subject, and measurements were taken both manually and using the automatic TALAS measurement tool included with CurveBeam’s CubeVue software. TALAS is a research tool and is not available for clinical use. This is significant as it is the first time that a study of the foot morphotypes of NBA players has been conducted.
The study found that, for the most part, NBA players have standard alignment in their lower extremities, although they do tend to have high arches and varus hindfoot alignment. These trends were slight, but they are related to foot injuries and should still be noted. Building up a database of weight-bearing CBCT scans of professional athletes could also allow specialists to have a new control group to compare scans to, which would be enormously beneficial., the study authors said.
Better analysis means better results
Incorporating weight-bearing CBCT scans like those of CurveBeam’s pedCAT can save players, and the league as a whole, both time and money in the long term. Not only will they be able to watch for warning signs, but they will have a complete view of available injuries and will could develop more specific training regimens geared towards returning athletes to the court as quickly as possible.
You can read the full study by Dr. de Cesar Netto, et al. here.
Some degree of subtalar joint subluxation, as well as sinus tarsi impingement, was found in approximately 70 percent of patients with flexible adult acquired flat foot (AAFD) in a recent imaging study using MRI and weight bearing CT (WBCT) imaging.
Investigators used the imaging to assess which soft tissue structures demonstrating MRI signs of degeneration would correlate and influence more positive findings of bone collapse.
The study results were on display in the poster section of the AAOS Annual Meeting and summarized by the AAOS Daily News.
Investiagators obtained MRI and WBCT imaging for 55 patients. Patients were evaluated for markers of arch collapse including increased valgus alignment of the hindfoot and forefoot abduction. Subfibular impingement was found in only 9 percent of patients.
“The significant and isolated influence of pronounced degeneration of the ligaments as positive indicators of more severe collapse of the bony architecture in AAFD patients, represented by subtalar joint subluxation and subfibular impingement, must be considered essential findings,” Dr. Cesar de Cesar Netto, a coauthor of the study, told AAOS News Daily. “Since we don’t really know which structures degenerate first in AAFD, our results point toward an increased importance of the ligamentous structures in the development and progression of the pathology, with the degeneration of the PTT potentially representing a late finding and only the tip of the ice berg.
The CurveBeam pedCAT is the only weight bearing CT imaging system with a field of view large enough to capture a bilateral foot and ankle scan. Flat foot degeneration is often a bilateral condition.
Ankle syndesmosis injury is one of the most common cases seen by foot and ankle specialists. An estimated 11% of all ankle injuries and 8.5-18% of all ankle fractures have injury to the syndesmosis. An inaccurate diagnosis can lead to chronic problems or repeat surgeries. Common indications for delayed surgery or reoperation include improper diagnosis, malreduction and inadequate fixation.
The syndesmosis connects the tibia and fibula above the ankle joint. One of the most difficult distinctions to make is whether the injury is isolated to the syndesmosis itself or if it has affected the stability of the ankle joint as well.
Dr. Daniel Guss, MD, MBA, assistant professor of orthopedic surgery at Harvard Medical School, took a deeper look at syndesmosis and how weight bearing CT imaging could improve diagnostic ability in a presentation he delivered to the WBCT International Study Group in July 2018.
Syndesmosis – Variabilities Are Common
The ankle syndesmosis serves two main functional purposes. First, it is designed to maintain the spatial relationship between the tibia and fibula in order to stabilize the ankle mortise throughout weight bearing activity. Second, it allows for flexibility of the ankle mortise in the coronal plane along the talar dome throughout various degrees and dorsiflexion and plantarflexion.
Dr. Guss reminded clinicians that when assessing the functional ability of the syndesmosis, it is important to note that recent studies have shown considerable variability in the concavity of the incisura, bony overlap, and clear space within the ankle mortise from one patient to another. In this regard, comparative anatomy images of the left and right ankle are essential for a thorough evaluation.
During a physical exam, the most common tests for evaluation of syndesmosis injury are external rotation stress test, calf squeeze test, and cross-legged test. By and large, all of these tests give greater indication of injury, but all have low sensitivity and specificity, Dr. Guss said. In addition, a positive test from any of these maneuvers is not considered diagnostic.
Imaging – Need for Contralateral Evaluation
Once history and physical exam have been completed, most clinicians turn to initial standard radiographs for evaluation. Tibia/fibula overlap, tibia/fibular clear space, and medial clear space are most often the areas of focus for more definitive diagnostic information in regard to instability. Most will attempt dynamic stress radiographs with high level of clinical suspicion.
However, Dr. Daniel Guss explained the importance of contralateral evaluation, as there has been great variability in measurements of the syndesmosis using weight bearing CT imaging within the same joint when measured in neutral, maximum external rotation, and maximum internal rotation. There is also evidence of significant syndesmosis measurement difference in weight bearing versus non-weight bearing images of uninjured ankles. This further illustrates the flexibility of the syndesmosis as a support structure.
Finally, if MRI is believed to be necessary, it is important to remember that this modality is very successful at detecting injury, but it does not shed any light on instability as it is a non-weight bearing image, Dr. Guss said.
Case Study – Undetected on X-Ray
Dr. Guss shared a case in which a 20-year-old male fell down a flight of stairs and thought he had sprained his ankle. He went to his college health services and obtained an X-Ray, which was negative for fracture. However, the X-Ray did show subtle calcifications within the syndesmoses.
X-Rays taken four months later at Dr. Guss’s clinic showed heterotopic ossification in the syndesmotic region.
Dr. Guss ordered a pedCAT weight bearing CT so he could assess the HO further. He was able to see the asymmetry under physiologic load at the distal tibio-fibular articulation and also that the HO was forming posterio-laterally.
The patient ultimately underwent an excision of the HO and fixation.
Case Study – Subtle Asymmetry
Dr. Guss shared another case where a Gentleman in his 50’s presented to the ER complaining of right ankle and lower leg pain after slipping on ice. Traditional x-rays were obtained, and he was diagnosed with a Maisonneuve-type injury with proximal fibula fracture and medial ankle sprain.
Upon follow up, the patient had a weight bearing CT scan done of both ankles that allowed for cross-section comparison under physiologic stress. This scan revealed subtle asymmetry and widening between the distal tibia and fibula of the injured right ankle compared to the non-injured left ankle.
Subsequently, this patient went on to have surgical fixation performed despite being told originally that he had simply sprained his ankle.
In conclusion, syndesmosis injury can be easily missed and yet carries long term implications for functional instability and chronic pain. When considering what imaging studies are necessary, it is essential to look at weight bearing and contralateral images to obtain a thorough picture of functional anatomy specific to that patient. As weight bearing CT technology becomes more widely available, this may be the most streamlined way to evaluate bilateral, weight bearing images to diagnose ankle syndesmosis instability.
Gaining an accurate and complete measurement of the hindfoot alignment of a patient with adult acquired flatfoot deformity (AAFD) is difficult when using traditional clinical assessment. In a paper published in the journal Foot and Ankle Surgery, Dr. Cesar de Cesar Netto, MD, PhD, and his colleagues posit that weight-bearing cone beam computed tomography (CBCT) scanning technology may give a more complete, three-dimensional view of the deformity and its underlying causes.
In the article, “Hindfoot Alignment of Adult Acquired Flatfoot Deformity,” the team studied twenty patients with AAFD, twelve men and eight women. All participants had to undergo a clinical assessment of their hindfoot alignment and got a weight-bearing CBCT scan. After all tests were completed, the team found that the weight-bearing CBCT scans provided far more accurate, reliable and repeatable measurements than those of the clinical assessments, thus making a strong case for the use of cone beam technology in AAFD diagnosis and treatment.
In the video below, Dr. de Cesar Netto describes how WBCT assists in AAFD evaluation. “We have been finding really interesting things while studying the flat foot deformities in the weight bearing CT images, most of them related to coronal plane assessment. But it’s not just that,” Dr. Cesar de Netto says. “We are trying to use the three dimensional environment to find out how the deformity progresses.”
The problem with current practices, according to de Cesar Netto and his colleagues, is that they rely on two systems that make it difficult to obtain universally accepted results. The first is radiographic examinations. These are two-dimensional and cumbersome, with further difficulty added when trying to discern hindfoot alignment due to the complexity of the subtalar joint. Not only that, but these examinations are especially prone to improper positioning which would throw off the results. The other traditional system used for hindfoot alignment measurement is made up of a series of clinical measurements including simple visual evaluation. These measurements have consistently been shown to be inaccurate and highly variable from physician to physician.
Recent advancements in CBCT technology now allow physicians to obtain a three-dimensional, highly detailed view of a patient’s lower extremities. They also allow for a complete picture of both the soft-tissue and bone within the foot, so that no issues go overlooked. Of particular interest to the study at hand was the fact that CBCT allows for scans to be taken of the foot in a natural, weight-bearing state. As AFFD is highly dynamic, analysis of the condition with the effects of a patient’s full body weight can be immensely beneficial when developing a treatment plan.
Leading the way with weight-bearing cone beam technology is CurveBeam. The CurveBeam LineUP is revolutionizing how physicians approach diagnosis and treatment plan development as their technology provides complete views of the lower extremities with high image quality.
A study published in the International Journal of Biomedicine concludes Cone Beam CT (CBCT) imaging is the “method of choice” for compound anatomical structures, such as the wrist, and post-traumatic changes in bone tissue.
“Considering the low dose radiation and high image quality,” CBCT could be used as a priority method of choice to assess the structure of wrist and hand bones and be done as a first step in diagnostics, replacing standard radiography,” according to the study, which was led by A. Yu Vasiliev PhD, MD, at Moscow State University of Medicine and Dentistry.
The wrist and hand are one of the regions in the human body most prone to injury and disease. Only one-fifth of incapacitation is the direct result of injury or disease. Many cases of incapacitation are instead due to mistakes made in diagnosis and treatment, according the study. Vasiliev and his team examined the capabilities of cone-beam computed tomography (CBCT) in the assessment of the structure of wrist and hand bones.
The study appeared in a 2013 issue of the International Journal of Biomedicine.
Vasiliev obtained a Cone-beam CT scan of the wrist and hand of a group of voluntary patients, which included 40 members aged 22 – 68 years. A Magnetic resonance imaging (МRI) exam was also performed on 80 percent of the volunteers, multi-slice CT scan was performed on 40 percent of the volunteers, and digital microfocus radiography and standard radiography exams were performed on 63 percent of the volunteers.
When all 40 CBCT scans were examined, structural changes of wrist and hand bones were detected in 77.5 percent of cases, and consolidated fractures and false joints of bones were detected in 10 percent of cases. All the changes were also detected by the multi-slice CT images and digital microfocus X-Rays, but were not defined on standard X-Rays.
The results demonstrated that CBCT provides high efficiency in detection of form, measurements and structural changes of bones of the anatomic region. The cone beam CT images of wrists and hands provided high-resolution, detailed mapping of bone structure, as well as accurate differentiation of bone trabeculae and minor structural changes and defects.
A new generation of cone-beam scanners makes it possible to obtain high-quality images without exposing the patient to a high dose of radiation. This facilitates more and better examinations in orthopedics and traumatology for better patient outcomes.
CurveBeam designs and manufactures Cone Beam CT imaging equipment for the orthopedic and podiatric specialties. To access the full study, please click here.
The team knew that the ability to assess OA with 2D radiographs was not good enough to detect subtle changes that could have important implications for patients, doctors, and researchers. To meet this challenge, they worked to develop a new algorithm for the structural assessment of joints including hips, knees and ankles in 3D. Their recent technical validation study showed the technique was successful.
The algorithm maps joint space width to the nearest tenth of a millimeter. Mapping joint space width in 3D from clinical CT data has the potential to enhance understanding of osteoarthritis and how patients progress to joint failure—leading to better and earlier interventions.
Early Detection Gives Osteoarthritis Patients More Options
The 3D mapping technique has the potential to be more than twice as sensitive as radiographs in detecting small changes in joint space widths. Using the algorithm, clinicians will be able to use CT scans to map a marker of osteoarthritis across a joint. Why does it matter? Because early detection leads to earlier treatment. Doctors could identify patients with disease earlier than the current gold standard, allowing important interventions to be started before the joint fails. Patients will have the opportunity to try lifestyle changes and physiotherapy instead of immediately facing surgery.
All clinical CT imaging was performed on a 64-slice Siemens Definition AS system.
“It will be an important next step to use JSM to investigate whether differences in positioning and load-bearing have any effect on joint space width in 3D,” the authors wrote. “A straightforward solution for prospective studies would be to perform knee and ankle CT in a standing position (as used in clinical practice), and to standardise supine hip positioning by strapping feet together.”
Evaluating New Therapies
In addition, the new 3D method will likely allow researchers to determine whether new therapies in development are effective in a realistic timescale for clinical trials. This is something that has not been possible using radiographs.
CurveBeam designs and manufactures Cone Beam CT imaging equipment for the orthopedic and podiatric specialties. Bilateral, weight bearing scans of the foot and ankle give physicians the information necessary to assess the biomechanical spatial relationships and alignment of the lower extremities.
To learn about a recent grant awarded to the University of Kansas to study joint space biomarkers via weight bearing CT, click here.
The University of Kansas Medical Center Research Institute Department of Rehabilitation Medicine has received a grant from the National Institute of Arthritis Musculoskeletal and Skin Diseases (NIAMS), one of the 27 Institutes and Centers at the National Institutes of Health (NIH), to fund three years of research on the usefulness of bilateral weight bearing CT imaging and the critical need for more sensitive and affordable imaging biomarkers.
Osteoarthritis (OA) is the most prevalent form of arthritis, and the knee is the most commonly affected weight-bearing joint. The high cost of clinical trials creates a barrier for effective treatment development. Therefore, introduction of more specific and sensitive biomarkers could help to advance therapeutic development by reducing the time and sample sizes required for clinical trials.
There is an urgent need for imaging biomarkers that allow for identification of the best time in which patients will respond to treatment, and a means to analyze the efficiency of interventions. Early studies demonstrated the diagnostic value of bilateral weight-bearing CT in identifying knee OA symptoms accurately, as well as the feasibility to detect meniscal tears not detected by non-weight bearing MRI.
The grant from NIAMS will fund a study to validate the proposed imaging biomarkers and begin the qualification process for more responsive OA imaging biomarkers acquired using low-dose, bilateral standing CT imaging. Substantial advantages are offered over traditional radiographic biomarkers, including increased responsiveness to temporal changes in the joints, and a better reflection of the symptoms and severity of the disease. Additionally, this research will determine the prognostic validity of standing CT findings for detecting progression and worsening pain in people who currently suffer from or are at risk for knee OA.
With the support of NIAMS, this research holds promise to detect joint damage earlier, and accelerate the pace of scientific discovery and clinical trials. The continuing impact will be evident through a shift in knee joint imaging with an improved biomarkers for monitoring knee OA disease features. If the additional meniscal extrusions detected on bilateral standing CT are clinically relevant, then standing CT could improve identification of the most appropriate patients for clinical trials – those at risk of rapid OA progression. Successful completion will provide improved biomarkers that will help those who suffer from knee OA through making clinical trials more affordable and accelerating therapeutic improvement.
For more information on visualizing cartilage and menisci in the knee using standing CT arthrogram versus MRI, click here.