Anterior cruciate ligament tears and associated meniscal lesions: assessment at dual-detector spiral CT arthrography

CT in musculoskeletal imaging: still helpful and for what?

Computed tomography (CT) is a common modality employed for musculoskeletal imaging. Conventional CT techniques are useful for the assessment of trauma in detection, characterization and surgical planning of complex fractures. CT arthrography can depict internal derangement lesions and impact medical decision making of orthopedic providers. In oncology, CT can have a role in the characterization of bone tumors and may elucidate soft tissue mineralization patterns. Several advances in CT technology have led to a variety of acquisition techniques with distinct clinical applications. These include four-dimensional CT, which allows examination of joints during motion; cone-beam CT, which allows examination during physiological weight-bearing conditions; dual-energy CT, which allows material decomposition useful in musculoskeletal deposition disorders (e.g., gout) and bone marrow edema detection; and photon-counting CT, which provides increased spatial resolution, decreased radiation, and material decomposition compared to standard multi-detector CT systems due to its ability to directly translate X-ray photon energies into electrical signals. Advanced acquisition techniques provide higher spatial resolution scans capable of enhanced bony microarchitecture and bone mineral density assessment. Together, these CT acquisition techniques will continue to play a substantial role in the practices of orthopedics, rheumatology, metabolic bone, oncology, and interventional radiology.

Dual-energy CT applications in musculoskeletal disorders

Dual-energy CT (DECT) is an exciting application in CT technology conferring many advantages over conventional single-energy CT at no additional with comparable radiation dose to the patient. Various emerging and increasingly established clinical DECT applications in musculoskeletal (MSK) imaging such as bone marrow oedema detection, metal artefact reduction, monosodium urate analysis, and collagen analysis for ligamentous, meniscal, and disc injuries are made possible through its advanced DECT post-processing capabilities. These provide superior information on tissue composition, artefact reduction and image optimization. Newer DECT applications to evaluate fat fraction for sarcopenia, Rho/Z application for soft tissue calcification differentiation, 3D rendering, and AI integration are being assessed for future use. In this article, we will discuss the established and developing applications of DECT in the setting of MSK radiology as well as the basic principles of DECT which facilitate them.

Imaging Biomarkers of Osteoarthritis

Currently no disease-modifying osteoarthritis drug has been approved for the treatment of osteoarthritis (OA) that can reverse, hold, or slow the progression of structural damage of OA-affected joints. The reasons for failure are manifold and include the heterogeneity of structural disease of the OA joint at trial inclusion, and the sensitivity of biomarkers used to measure a potential treatment effect.This article discusses the role and potential of different imaging biomarkers in OA research. We review the current role of radiography, as well as advances in quantitative three-dimensional morphological cartilage assessment and semiquantitative whole-organ assessment of OA. Although magnetic resonance imaging has evolved as the leading imaging method in OA research, recent developments in computed tomography are also discussed briefly. Finally, we address the experience from the Foundation for the National Institutes of Health Biomarker Consortium biomarker qualification study and the future role of artificial intelligence.

Dual energy CT in musculoskeletal applications beyond crystal imaging: bone marrow maps and metal artifact reduction

Dual energy CT (DECT) is becoming increasingly popular and valuable in the domain of musculoskeletal imaging. Gout maps and crystal detection have been predominant indications for about a decade. Other important indications of bone marrow maps and metal artifact reduction are also frequent with added advantages of detection and characterization of bone marrow lesions similar to MR imaging and diagnosis of hardware related complications, respectively. This article discusses technical considerations and physics of DECT imaging and its role in musculoskeletal indications apart from crystal imaging with respective case examples and review of the related literature. DECT pitfalls in these domains are also highlighted and the reader can gain knowledge of above concepts for prudent use of DECT in their musculoskeletal and general practices.

Imaging in Osteoarthritis

Osteoarthritis (OA) is the most frequent form of arthritis with major implications on both individual and public health care levels. The field of joint imaging, and particularly magnetic resonance imaging (MRI), has evolved rapidly due to the application of technical advances to the field of clinical research. This narrative review will provide an introduction to the different aspects of OA imaging aimed at an audience of scientists, clinicians, students, industry employees, and others who are interested in OA but who do not necessarily focus on OA. The current role of radiography and recent advances in measuring joint space width will be discussed. The status of cartilage morphology assessment and evaluation of cartilage biochemical composition will be presented. Advances in quantitative three-dimensional morphologic cartilage assessment and semi-quantitative whole-organ assessment of OA will be reviewed. Although MRI has evolved as the most important imaging method used in OA research, other modalities such as ultrasound, computed tomography, and metabolic imaging play a complementary role and will also be discussed.

Ex vivo comparison of 3 Tesla magnetic resonance imaging and multidetector computed tomography arthrography to identify artificial soft tissue lesions in equine stifles

OBJECTIVE

To determine the diagnostic performance of computed tomographic arthrography (CTA) and 3 Tesla magnetic resonance imaging (MRI) for detecting artificial meniscal, meniscotibial ligament (MTL) lesions and cruciate ligament (CL) lesions in horses.

STUDY DESIGN

Ex vivo controlled laboratory study.

ANIMALS

Nineteen stifles from adult horses.

METHODS

Stablike defects (n = 84) (16 mm long, 10 mm deep) were created in the menisci (n = 35), CLs (n = 24), and MTLs (n = 25) via arthroscopy prior to MRI and CTA (80 mL contrast at 85 mg/mL per joint). Two radiologists, unaware of the lesions, reached a consensus regarding the presence of lesions, based on 2 reviews of each study. Sensitivity and specificity of MRI and CTA were determined using arthroscopy as a reference and compared with McNemar's tests.

RESULTS

The sensitivity and specificity of MRI (41% and 86% respectively) and CTA (32% and 90% respectively) did not differ (P = .65). The sensitivity (MRI: 24%‐50%; CTA:19%‐40%) and specificity (MRI: 75%‐92%; CTA 75%‐100%) of imaging modalities did not differ when detecting lesions of the menisci, MTLs, and CLs (P = .1‐1.0). The highest sensitivities were achieved when MTLs were evaluated with MRI (50%) and CLs with both modalities (40%).

CONCLUSIONS

The diagnostic performance of CTA was comparable with that of MRI, with a low to moderate sensitivity and high specificity.

CLINICAL SIGNIFICANCE

Computed tomographic arthrography should be considered as an adjunct to diagnose CL injuries. This is important for equine clinicians, as the CL cannot be visualized adequately using basic imaging techniques preoperatively.

Discovering Knee Osteoarthritis Imaging Features for Diagnosis and Prognosis: Review of Manual Imaging Grading and Machine Learning Approaches

Knee osteoarthritis (OA) is a deliberating joint disorder characterized by cartilage loss that can be captured by imaging modalities and translated into imaging features. Observing imaging features is a well-known objective assessment for knee OA disorder. However, the variety of imaging features is rarely discussed. This study reviews knee OA imaging features with respect to different imaging modalities for traditional OA diagnosis and updates recent image-based machine learning approaches for knee OA diagnosis and prognosis. Although most studies recognized X-ray as standard imaging option for knee OA diagnosis, the imaging features are limited to bony changes and less sensitive to short-term OA changes. Researchers have recommended the usage of MRI to study the hidden OA-related radiomic features in soft tissues and bony structures. Furthermore, ultrasound imaging features should be explored to make it more feasible for point-of-care diagnosis. Traditional knee OA diagnosis mainly relies on manual interpretation of medical images based on the Kellgren-Lawrence (KL) grading scheme, but this approach is consistently prone to human resource and time constraints and less effective for OA prevention. Recent studies revealed the capability of machine learning approaches in automating knee OA diagnosis and prognosis, through three major tasks: knee joint localization (detection and segmentation), classification of OA severity, and prediction of disease progression. AI-aided diagnostic models improved the quality of knee OA diagnosis significantly in terms of time taken, reproducibility, and accuracy. Prognostic ability was demonstrated by several prediction models in terms of estimating possible OA onset, OA deterioration, progressive pain, progressive structural change, progressive structural change with pain, and time to total knee replacement (TKR) incidence. Despite research gaps, machine learning techniques still manifest huge potential to work on demanding tasks such as early knee OA detection and estimation of future disease events, as well as fundamental tasks such as discovering the new imaging features and establishment of novel OA status measure. Continuous machine learning model enhancement may favour the discovery of new OA treatment in future.

The imaging evaluation of acetabular labral lesions

The acetabular labrum is an important structure that contributes to hip joint stability and function. Diagnosing labral tears involves a comprehensive assessment of clinical symptoms, physical examinations, imaging examinations, and arthroscopic confirmation. As arthroscopy is an invasive surgery, adjuvant imaging of the acetabular labrum is increasingly imperative for orthopedists to diagnose and assess labral lesions prior to hip arthroscopy for surgical management. This article reviews the current imaging strategies for the evaluation of labrum lesions.

MRI appearance of the different meniscal ramp lesion types, with clinical and arthroscopic correlation

BACKGROUND

Meniscal ramp lesions have been defined as longitudinal vertical peripheral tears of the medial meniscus involving the posterior meniscocapsular ligament, meniscotibial ligament, and/or the red-red zone of the posterior horn. They are heavily associated with anterior cruciate ligament injuries, and because of their potentially important biomechanical role in knee stabilization, injuries to this region may require surgical repair. However, due to their location and lack of general knowledge regarding their different types and associated appearances on magnetic resonance imaging, ramp lesions are routinely underreported. This is compounded by the fact that ramp lesions are also often overlooked during conventional anterior portal arthroscopy when direct visualization is not achieved.

PURPOSE

To demonstrate MRI appearances and arthroscopic findings of the different types of meniscal ramp lesions, in the hopes of improving their detection on pre-operative imaging.

Assessment of the anterolateral ligament of the knee by 1.5 T magnetic resonance imaging

Objective This study was performed to evaluate the visibility of the knee's anterolateral ligament (ALL) by magnetic resonance (MR) imaging when evaluating injuries of the ALL in relation to injuries of the anterior cruciate ligament (ACL). Methods Two reviewers retrospectively analyzed MR images for the visibility and dimensions of the ALL and the relationship between ALL and ACL injuries. The intraclass correlation coefficient (ICC) and kappa analysis were used to assess interobserver reliability. The chi-square test was used to assess the relationship between ALL and ACL injuries. Results The entire ALL was viewed on 82% of all MR images. The ICC for ALL visualization ranged from moderate to perfect between the two readers. There was almost perfect agreement between the reviewers when evaluating ALL dimensions. The mean length ± standard error, median thickness, and mean width ± standard error of the ALL were 36.5 ± 0.6 mm, 2.5 mm, and 8.2 ± 0.2 mm, respectively. A statistically significant relationship was observed between ALL and ACL injuries. Conclusion The ALL was visible on most MR images, allowing ALL injuries to be noted during routine MR image interpretation. Radiologists should note concomitant ACL and ALL injuries as part of their assessments.

SPECT/CT arthrography

Single photon emission CT (SPECT)/CT arthrography, the combination of CT arthrography and late phase bone SPECT/CT, has been developed in 2011 and so far used in knee, ankle and wrist joints. SPECT/CT offers functional information about increased bone turnover in combination with morphological details. Compared with SPECT/CT alone, additional intra-articular contrast enables the assessment of cartilage, menisci, ligaments and loose bodies. SPECT/CT arthrography is a promising alternative technique for the evaluation of internal derangement of joints in patients with MR contraindications and/or metallic implants. In this article, we review and report our 5-year experience with this technique illustrated with patient examples and give a perspective for future applications.

Dual-Energy CT for the Musculoskeletal System

The principal advantages of dual-energy computed tomography (CT) over conventional CT in the musculoskeletal setting relate to the additional information provided regarding tissue composition, artifact reduction, and image optimization. This article discusses the manifestations of these in clinical practice-urate and bone marrow edema detection, metal artifact reduction, and tendon analysis, with potential in arthrography, bone densitometry, and metastases surveillance. The basic principles of dual-energy CT physics and scanner design will also be discussed. ^© RSNA, 2016.

Prospective Evaluation of Agreement and Accuracy in the Diagnosis of Meniscal Tears: MR Arthrography a Short Time After Injection Versus CT Arthrography After a Moderate Delay

OBJECTIVE

The purpose of this study was to compare the performance of direct CT arthrography performed after a moderate injection delay with that of MR arthrography performed soon after injection in the diagnosis of meniscal tears.

SUBJECTS AND METHODS

Twenty-five patients underwent direct MR arthrography followed by same-day CT arthrography of the knee. Two blinded musculoskeletal radiologists independently reviewed the MR and CT arthrographic images for the presence of medial or lateral meniscal tears in the anterior horn, body, and posterior horn. Their readings were compared with a reference standard reading, which was based on post-MRI arthroscopic findings (n = 11) or the consensus opinion of two other musculoskeletal radiologists who simultaneously reviewed the paired CT and MR arthrographic examinations using all available clinical, surgical, and imaging information. The individual and combined radiologist agreements with the reference standard were calculated for each modality.

RESULTS

Interreader agreement was 91% for MR arthrography and 85% for CT arthrography. The overall combined radiologist agreement with the reference standard was 91% for MR arthrography and 86% for CT arthrography (p = 0.03). For the two readers, the overall accuracy rates for diagnosing a meniscal tear were 82% and 88% with MR arthrography and 74% and 76% with CT arthrography. Only 50% (3/6) of surgically proven tears imbibed gadolinium.

CONCLUSION

Although MR arthrography performed soon after the contrast injection had higher interreader agreement and greater accuracy, CT arthrography performed after a mean postinjection delay of 100 minutes was moderately accurate in the diagnosis of meniscal tears and can be used as an alternative procedure when MR arthrography cannot be completed.

Epinephrine-enhanced computed tomographic arthrography of the canine shoulder

The aim of this study was to investigate the effect of epinephrine-enhanced computed tomographic arthrography (CTA) on the image sharpness of the lateral and medial glenohumeral ligaments (LGHL and MGHL, respectively), biceps tendon (BT) and joint cartilage (JC) in the canine shoulder. The shoulders of eight normal dogs were examined using a 4-slice helical CT scanner. The right shoulders were injected with Iohexol and the left shoulders with a mixture of Iohexol and epinephrine. CTA images were obtained after 1, 3, 5, 9, 13, 20 and 30 min and the image sharpness of the intra-articular structures in both shoulders was graded for visibility. The attenuation values were measured to examine the persistence of contrast appearance. Admixture of epinephrine and Iohexol significantly improved the image sharpness of the LGHL and the BT, especially on delayed CTA images. The use of epinephrine did not negatively affect post-CTA recovery.

Assessment of the diagnostic value of dual-energy CT and MRI in the detection of iatrogenically induced injuries of anterior cruciate ligament in a porcine model

INTRODUCTION

Magnetic resonance imaging (MRI) is the standard of reference for the non-invasive evaluation of ligament injuries of the knee. The development of dual-energy CT (DE-CT) made it possible to differentiate between tissues of different density by two simultaneous CT measurements with different tube voltages. This approach enables DE-CT to discriminate ligament structures without intra-articular contrast media injection. The aims of this study were on the one hand to determine the delineation of the anterior cruciate ligament (ACL) and on the other hand to assess the diagnostic value of DE-CT and MRI in the detection of iatrogenically induced injury of the ACL in a porcine knee joint model.

MATERIALS AND METHODS

Twenty porcine hind legs, which were placed in a preformed cast in order to achieve a standardized position, were scanned using DE-CT. Thereafter, a 1.5-T MRI using a standard protocol was performed. The imaging procedures were repeated with the same parameters after inducing defined lesions (total or partial incision) on the ACL arthroscopically. After post-processing, two radiologists and two orthopedic surgeons first analyzed the delineation of the ACL and then, using a consensus approach, the iatrogenically induced lesions. The result of the arthrotomy was defined as the standard of reference.

RESULTS

The ACL could be visualized both on DE-CT and MRI in 100% of the cases. As for the MRI, the sensitivity and specificity of detecting the cruciate ligament lesion respectively compared with the defined arthrotomy was 66.7% and 78.6% for intact cruciate ligaments, 100% and 75% in the case of a complete lesion, 33.3% and 78.6% for lesions of the anteromedial bundle, and 0% and 100% for lesions of the posterolateral bundle. In comparison, DE-CT demonstrated a sensitivity and specificity of 66.7% and 71.4% in the case of intact cruciate ligaments, 75% and 68.8% in the case of completely discontinued ACLs, 0% and 92.9% in the case of lesions of the anteromedial bundle, and 25% and 87.5% in the case of lesions of the posterolateral bundle.

CONCLUSIONS

The present ex vivo experiment shows that both study modalities (DE-CT and MRI) are equal with regard to the delineation of the ACL, while MRI achieved higher sensitivity and specificity regarding iatrogenically induced complete ACL lesions. DE-CT could be a possible alternative to MRI for certain indications in the diagnosis of a knee ligament injury.

Bath Concentration of Anionic Contrast Agents Does Not Affect Their Diffusion and Distribution in Articular Cartilage In Vitro

OBJECTIVE

Differences in contrast agent diffusion reflect changes in composition and structure of articular cartilage. However, in clinical application the contrast agent concentration in the joint capsule varies, which may affect the reliability of contrast enhanced cartilage tomography (CECT). In the present study, effects of concentration of x-ray contrast agents on their diffusion and equilibrium distribution in cartilage were investigated.

DESIGN

Full-thickness cartilage discs (d = 4.0 mm, n = 120) were detached from bovine patellae (n = 24). The diffusion of various concentrations of ioxaglate (5, 10, 21, 50 mM) and iodide (30, 60, 126, 300 mM) was allowed only through the articular surface. Samples were imaged with a clinical peripheral quantitative computed tomography scanner before immersion in contrast agent, and after 1, 5, 9, 16, 25, and 29 hours in the bath.

RESULTS

Diffusion and partition coefficients were similar between different contrast agent concentrations. The diffusion coefficient of iodide (473 ± 133 µm(2)/s) was greater (P ≤ 0.001) than that of ioxaglate (92 ± 46 µm(2)/s). In full-thickness cartilage, the partition coefficient (at 29 h) of iodide (71 ± 5%) was greater (P ≤ 0.02 with most concentrations) than that of ioxaglate (62 ± 6%).

CONCLUSIONS

Significant differences in partition and diffusion coefficient of two similarly charged (-1) contrast agents were detected, which shows the effect of steric interactions. However, the increase in solute concentration did not increase its partition coefficient. In clinical application, it is important that contrast agent concentration does not affect the interpretation of CECT imaging.

A study of the anatomy and injection techniques of the ovine stifle by positive contrast arthrography, computed tomography arthrography and gross anatomical dissection

Although ovine stifle models are commonly used to study osteoarthritis, meniscal pathology and cruciate ligament injuries and repair, there is little information about the anatomy of the joint or techniques for synovial injections. The objectives of this study were to improve anatomical knowledge of the synovial cavities of the ovine knee and to compare intra-articular injection techniques. Synovial cavities of 24 cadaver hind limbs from 12 adult sheep were investigated by intra-articular resin, positive-contrast arthrography, computed tomography (CT) arthrography and gross anatomical dissection. Communication between femoro-patellar, medial femoro-tibial and lateral femoro-tibial compartments occurred in all cases. The knee joint should be considered as one synovial structure with three communicating compartments. Several unreported features were observed, including a communication between the medial femoro-tibial and lateral femoro-tibial compartments and a latero-caudal recess of the lateral femoro-tibial compartment. No intermeniscal ligament was identified. CT was able to define many anatomical features of the stifle, including the anatomy of the tendinous synovial recess on the lateral aspect of the proximal tibia under the combined tendon of the peroneus tertius, extensor longus digitorum and extensor digiti III proprius. An approach for intra-articular injection into this recess (the subtendinous technique) was assessed and compared with the retropatellar and paraligamentous techniques. All three injection procedures were equally successful, but the subtendinous technique appeared to be most appropriate for synoviocentesis and for injections in therapeutic research protocols with less risk of damaging the articular cartilage.

Imaging of the anterior cruciate ligament

The anterior cruciate ligament (ACL) is an important structure in maintaining the normal biomechanics of the knee and is the most commonly injured knee ligament. However, the oblique course of the ACL within the intercondylar fossa limits the visualization and assessment of the pathology of the ligament. This pictorial essay provides a comprehensive and illustrative review of the anatomy and biomechanics as well as updated information on different modalities of radiological investigation of ACL, particularly magnetic resonance imaging.

Current concepts and advances: computerized tomography in sports medicine

Computed tomography (CT) is a widely used imaging technique. With the introduction of multidetector row technology, CT has been further refined. Although the focus of this transformation has been body and cardiac imaging, orthopedic imaging has benefited greatly. Specifically, the improvements in CT have made it possible to obtain submillimeter-thick slices that enable the creation of high-resolution multiplanar reformations from a single scan. These images usually are indistinguishable from direct plane acquisitions and provide unparalleled detail. Additionally, the factors responsible for causing CT image artifacts when hardware is present are much better understood and the improvements in CT technique and technology can be exploited to provide better images of patients with orthopedic hardware. The detailed multiplanar visualization of joints facilitates CT arthrography that has undergone a renaissance. CT arthrography is useful in the very large athlete or patient, the claustrophobic, and for those patients who fail a conventional magnetic resonance examination or magnetic resonance arthrogram.

Evaluation of partial cranial cruciate ligament rupture with positive contrast computed tomographic arthrography in dogs

Computed tomographic arthrography (CTA) of four cadaveric canine stifles was performed before and after partial cranial cruciate ligament rupture in order to verify the usefulness of CTA examination for the diagnosis of partial cranial cruciate ligament rupture. To obtain the sequential true transverse image of a cranial cruciate ligament, the computed tomography gantry was angled such that the scanning plane was parallel to the fibula. True transverse images of cranial cruciate ligaments were identified on every sequential image, beginning just proximal to the origin of the cranial cruciate ligament distal to the tibial attachment, after the administration of iodinated contrast medium. A significant decrease in the area of the cranial cruciate ligament was identified on CTA imaging after partial surgical rupture of the cranial cruciate ligament. This finding implies that CTA can be used for assessing partial cranial cruciate ligament ruptures in dogs.

Signification of the unusual delineation of the anterior meniscofemoral ligament of Humphrey during knee arthro-CT

BACKGROUND

Meniscofemoral ligaments (MFLs) are recognized as stabilizing and protective structures for the posterolateral meniscocondylar compartment of the knee, and as secondary restraints to tibial posterior translation.

PURPOSE AND PATIENTS

We report the 64-row arthro-MDCT findings of 10 patients (8 males, 2 females; mean age 43.8 years) in which the anterior MFL of Humphrey (aMLF) was atypically well delineated by an unusual circumferential effusion of iodine contrast. We discuss a possible physiopathologic mechanism for this effusion, describe the MDCT anatomy of the aMLF and review the literature about the anatomy and physiology of the MFLs.

RESULTS

In each of our ten patients an unusual effusion of articular contrast was found delineating a posterior oblique ligamentar bundle, which was running in front of the posterior cruciate ligament (PCL). This bundle was best appreciated on posterior coronal oblique and sagital MPR views, and was recognized as the aMFL. The finding was associated with a partial tear of the tibial insertion of the posterior horn (PH) of the lateral meniscus (LM) in three patients, and with a partial (two cases) or subtotal (three cases) tear of the PCL in five patients. A swollen-probably oedematous-PCL was found in another patient and in the last case the anomaly was minimal and remained isolated. All patients were treated conservatively.

CONCLUSION

Since the aMFL inserts inferiorly into the posterior horn of the LM and runs in very close anatomic and functional relation with the PCL, we hypothesize that a trauma producing a tear in these structures may also occasionally sufficiently stretch the aMFL to produce a peripheral loosening allowing a circumferential effusion of opacified synovial fluid around the ligament. Our report offers the opportunity to illustrate the "in vivo" anatomy of the aMFL through original unpublished figures. It also contributes to reinforce the literature data concerning the potential fine mechanical role played by the LM-MFLs-PCL complex, in which the centrally located MFLs act laterally as stabilizing and protective structures for the posterolateral meniscocondylar compartment and medially as secondary restraints to tibial posterior translation.

Meniscal healing after meniscal repair: a CT arthrography assessment

BACKGROUND

Studies evaluating healing of repaired meniscus are rare and primarily retrospective. The aim of this study was to assess whether there were different healing rates for arthroscopic meniscal repair with respect to the different zones of the meniscus.

PURPOSE

This study was conducted to assess outcomes and to document anatomic characteristics of the repaired meniscus with postoperative arthrography combined with computed tomography (arthro-CT), particularly the dimensions and healing of the repaired meniscus.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Fifty-three arthroscopic meniscal repairs were prospectively evaluated between 2002 and 2004 in 2 orthopaedic departments. There were 36 medial and 17 lateral torn menisci. All ACL tears (n = 31, 58.5%) underwent reconstruction. Patients were preoperatively evaluated by magnetic resonance imaging. Clinical evaluation included International Knee Documentation Committee (IKDC) scores before the operation and 6 and 12 months afterward. Healing criteria were evaluated at 6 months by arthro-CT scan. Three parameters were evaluated--healing in thickness (Henning criteria), overall healing rate, and reduction in the width of the remaining meniscus.

RESULTS

According to the objective IKDC score, 26 patients were graded A, 20 B, and 4 C (92% good results). The mean subjective IKDC score was 78.9 (standard deviation [SD], 16.2). According to Henning's criteria, 58% of the menisci healed completely, 24% partially, and 18% failed. The overall healing rate was 73.1% (SD, 38.5). Twenty tears located in the posterior part had a healing rate of 59.8% (SD, 46.0). Nineteen tears extending from the posterior to the middle part had a healing rate of 79.2% (SD, 28.2). Isolated tears located in the posterior part had a lower healing rate (P < .05). There was a 9% +/- 1.2% reduction in the width of the remaining medial meniscus in the middle and posterior repaired portions (P < .02). There was a 15% +/- 14% reduction in the width of the remaining lateral meniscus in the middle repaired portion (P < .01). Complete healing of the posterior segment was associated with reduction in the width of the meniscus (P < .04).

CONCLUSION

A modern technique using all-inside fixation or outside-in sutures provided good clinical and anatomic outcomes. No statistically significant effect on ACL reconstruction or laterality (medial vs lateral) on overall healing after meniscal repair was identified. Partial healing occurred often, with a stable tear on a narrowed and painless meniscus. The posterior segment healing rate remained low, suggesting a need for further technical improvements.

Disorders of acetabular labrum and articular cartilage in hip dysplasia: evaluation using isotropic high-resolutional CT arthrography with sequential radial reformation

OBJECTIVE

Acetabular labral tear may predispose to adjacent articular cartilage disorder and hip osteoarthritis in patients with hip dysplasia. We evaluated the diagnostic ability of isotropic computed tomography (CT) arthrography with radial reformation technique for detection of acetabular labral and articular cartilage disorders, and evaluate those interactions in hip dysplasia.

METHODS

Forty-one hips in 29 patients with hip dysplasia received CT arthrography with isotropic spatial resolution of 0.5mm. After processing of multiplanar radial reformation over the whole acetabular circumference, frequencies of labral tear and acetabular cartilage disorder were evaluated at six divided zones of the weight-bearing areas. Of the 41 hips, 20 hips underwent arthroscopic examinations, and sensitivity, specificity and accuracy for detecting labral tear and acetabular cartilage disorder by CT arthrography were calculated using the arthroscopic findings as the standard of reference.

RESULTS

The sensitivity, specificity and accuracy of CT arthrography were 97%/87%/92% for labral tear and 88%/82%/85% for acetabular cartilage disorder, respectively, using arthroscopic findings as the reference. The CT arthrography showed significantly higher frequency of labral and acetabular cartilage disorders at the anterior zones. Those zones with labral tear had significantly higher frequency of adjacent cartilage disorder than zones without labral tear.

CONCLUSIONS

Isotropic CT arthrography with radial reformation technique allowed simultaneous, accurate assessment of labral and cartilage disorders in the whole acetabular circumference. Our findings indicated that labral tear is closely associated with adjacent cartilage disorder in hip dysplasia.

Fat-Suppressed 3D Spoiled Gradient-Echo MRI and MDCT Arthrography of Articular Cartilage in Patients with Hip Dysplasia

OBJECTIVE

Our objective was to assess the diagnostic ability of MDCT arthrography for acetabular and femoral cartilage lesions in patients with hip dysplasia.

MATERIALS AND METHODS

A disorder of the articular cartilage was evaluated in 20 hips of 18 patients with acetabular dysplasia who did not have osteoarthritis or who had early stage osteoarthritis before undergoing pelvic osteotomy surgery. The findings on fat-suppressed 3D fast spoiled gradient-echo MRI and MDCT arthrography of the hip were evaluated by two independent observers, and sensitivity, specificity, and accuracy were determined using arthroscopic findings as the standard of reference. Kappa values were calculated to quantify the level of interobserver agreement.

RESULTS

The sensitivity and specificity for the detection of any cartilage disorder (grade 1 or higher) were (observer 1/observer 2) 49%/67% and 89%/76%, respectively, on MRI, and 67%/67% and 89%/82%, respectively, on CT arthrography. The sensitivity and specificity for the detection of cartilage lesions with substance loss (grade 2 or higher) were (observer 1/observer 2) 47%/53% and 92%/87%, respectively, on MRI, and 70%/79% and 93%/94%, respectively, on CT arthrography. CT arthrography provided significantly higher sensitivity in the detection of grade 2 or higher lesions than MRI for both observers. Interobserver agreement in the detection of grade 2 or higher cartilage lesions was moderate (kappa = 0.53) on MRI and substantial (kappa = 0.78) on CT.

CONCLUSION

MDCT arthrography is a sensitive and reproducible method for assessing articular cartilage lesions with substance loss in patients with hip dysplasia.

Imaging the post-operative meniscus

Considerable developments have occurred in meniscal surgery, and consequently in the imaging of post-operative menisci, over the last 15 years. A drive to preserve meniscal physiologic function for as long as possible, in order to delay osteoarthrosis, has resulted in limited partial meniscectomies, meniscal repairs and meniscal transplants. Each of these techniques affects the imaging appearance of the meniscus, reducing the accuracy of conventional MRI in predicting recurrent tears. The specificity of conventional MRI can be improved by employing at least two T2-weighted sequences, but this still leaves a shortfall in sensitivity. In an attempt to increase the diagnostic accuracy of cross-sectional imaging, MR arthrography (MRA) and CT arthrography (CTA), have been applied to the post-operative meniscus. Sensitivities and specificities for these two techniques approach 90% in predicting recurrent meniscal tears. In the setting of clinical symptoms and gross meniscal deficiency, meniscal allografts are being transplanted with increasing frequency. In these transplants meniscal degeneration, fragmentation and separation are common findings, but the role of imaging in the management of these patients has not yet been well defined. This review explores the imaging techniques available for the evaluation of the post-operative meniscus, their strengths and weaknesses, and the reasons that they may find a place in a rational strategy for imaging of the symptomatic post-operative knee.

Intra-articular findings in the reconstructed multiligament-injured knee

PURPOSE

Intra-articular chondral and meniscal injury in the multiligament-injured knee has not been examined. The purpose of this study was to determine the pattern of intra-articular chondral and meniscal damage in subjects with multiligament knee injuries undergoing surgery.

TYPE OF STUDY

Prospective cohort study.

METHODS

Analysis was performed on prospectively collected data for the presence of meniscal tears and significant chondral injury on subjects who underwent knee ligament surgery. Subjects were grouped by their multiligament injury combination. Chondral injury was graded using the Modified Outerbridge Classification system. Criteria for significant chondral defect were any grade 2 lesion involving 50% or more of condylar width and all grade 3 or 4 lesions. Groups with more than 10 subjects were compared against the anterior cruciate ligament (ACL)-only group.

RESULTS

Data were collected on 2,265 subjects. The ACL/medial collateral ligament (MCL) injury pattern was the most common multiligament injury, comprising 70.5% of all multiligament injuries. Lateral meniscal damage was significantly higher in the ACL/MCL group (P < .01). Medial meniscal damage was significantly lower in the ACL/MCL group (P < .01). Medial and lateral meniscal damage was significantly lower in the ACL/lateral collateral ligament (LCL) group (P < .01). Articular damage to the medial tibial plateau was significantly lower in the ACL/MCL group (P < .01). All other multiligament injury patterns showed chondral damage similar to the ACL-only group. Ligament injuries repaired acutely had significantly less articular and medial meniscal damage than chronic repairs (P < .01).

CONCLUSIONS

The ACL/MCL injury pattern was the most common multiligament injury pattern and showed a high incidence of lateral meniscal tears. ACL/LCL injuries had fewer meniscal injuries. Multiligament-injured knees showed increased risk of a torn medial meniscus as chronicity increased.

LEVEL OF EVIDENCE

Level IV.

COMPUTED TOMOGRAPHIC ARTHROGRAPHY OF THE NORMAL CANINE STIFLE

Computed tomographic (CT) imaging of eight normal cadaveric canine stifles was performed before and after intra-articular administration of iodinated contrast medium. Transverse CT images were reconstructed in dorsal, parasagittal, and oblique planes. The following ligamentous structures were identified on transverse CT images in all stifles: cranial cruciate ligament, caudal cruciate ligament, medial meniscus, lateral meniscus, and the medial and lateral collateral ligaments. The following ligamentous structures were identified on transverse computed tomographic arthrography (CTA) images in all stifles: cranial cruciate ligament, caudal cruciate ligament, medial meniscus, lateral meniscus, meniscofemoral ligament, cranial meniscotibial ligaments, caudal meniscotibial ligaments, intermeniscal (transverse) ligament, and the medial and lateral collateral ligaments. The patellar tendon was identified on transverse and reconstructed dorsal and sagittal CT and CTA images in all stifles. Multiplanar reconstructions enabled further evaluation of the continuity of the cranial and caudal cruciate ligaments and menisci. The medial and lateral collateral ligaments were not clearly identified on CT or CTA multiplanar reconstructed images.

CT arthrography and virtual arthroscopy in the diagnosis of the anterior cruciate ligament and meniscal abnormalities of the knee joint

Objective

To determine the diagnostic accuracy of CT arthrography and virtual arthroscopy in the diagnosis of anterior cruciate ligament and meniscus pathology.

Materials and Methods

Thirty-eight consecutive patients who underwent CT arthrography and arthroscopy of the knee were included in this study. The ages of the patients ranged from 19 to 52 years and all of the patients were male. Sagittal, coronal, transverse and oblique coronal multiplanar reconstruction images were reformatted from CT arthrography. Virtual arthroscopy was performed from 6 standard views using a volume rendering technique. Three radiologists analyzed the MPR images and two orthopedic surgeons analyzed the virtual arthroscopic images.

Results

The sensitivity and specificity of CT arthrography for the diagnosis of anterior cruciate ligament abnormalities were 87.5%-100% and 93.3-96.7%, respectively, and those for meniscus abnormalities were 91.7%-100% and 98.1%, respectively. The sensitivity and specificity of virtual arthroscopy for the diagnosis of anterior cruciate ligament abnormalities were 87.5% and 83.3-90%, respectively, and those for meniscus abnormalities were 83.3%-87.5% and 96.1-98.1%, respectively.

Conclusion

CT arthrography and virtual arthroscopy showed good diagnostic accuracy for anterior cruciate ligament and meniscal abnormalities.

Magnetic Resonance Diagnosis of Meniscal Tears in Patients With Acute Anterior Cruciate Ligament Tears

OBJECTIVE

To evaluate the accuracy of magnetic resonance imaging in the diagnosis of meniscal tear in patients with acute anterior cruciate ligament tears.

METHODS

Magnetic resonance images obtained from 41 patients imaged within 6 weeks of injury who had acute anterior cruciate ligament tears identified at arthroscopy were retrospectively reviewed for meniscal tear.

RESULTS

With MR imaging the sensitivity, specificity and accuracy for diagnosing meniscal tears in the presence of acute anterior cruciate ligament tears were 71%, 93%, and 88%; for the lateral meniscal tears were 57%, 100% and 85%; and for the medial meniscal tears were 100%, 88%, 90%. All false negative cases (n = 6) involved the posterior horn of the lateral meniscus.

CONCLUSION

In the presence of acute anterior cruciate ligament tears, MRI imaging has relatively low sensitivity for detecting meniscal tears due to missed tears in the lateral meniscus.

Postoperative meniscus: assessment at dual-detector row spiral CT arthrography of the knee

PURPOSE

To assess the effectiveness of dual-detector row spiral computed tomographic (CT) arthrography of the knee in the evaluation of the postoperative meniscus for recurrent or residual meniscal tear.

MATERIALS AND METHODS

Spiral CT arthrography was performed in 20 patients who presented with pain after partial meniscectomy. Findings at the initial reading of the images and at two retrospective independent readings were compared with those at second-look arthroscopy performed in all patients. At initial interpretation, conventional criteria for meniscal tear were used, including partial- or full-thickness tear of any size and meniscal separation. At retrospective interpretation, criteria for meniscal tear included large partial- and full-thickness tear and meniscal separation but not small partial-thickness tear. Sensitivity and specificity for the detection of tear of the postoperative menisci were calculated for initial and retrospective readings.

RESULTS

At initial interpretation, the sensitivity and specificity for the detection of tear of the postoperative menisci were 100% and 78%, respectively. At retrospective interpretation, the sensitivity and specificity for the detection of tear of the postoperative menisci were 79% and 89% at reading 1 and 93% and 89% at reading 2, respectively.

CONCLUSION

Spiral CT arthrography is valuable for the assessment of postoperative menisci, but the application of conventional definitions of meniscal tear to arthrographic findings in postoperative menisci can lead to overestimation of the clinical importance of meniscal lesions.