Imaging of Cysts and Bursae About the Knee

Ossified Superficial Infrapatellar Bursa: A Case Report

Bursitis, though treatable conservatively, very rarely can have ossification and calcification in its substance which requires surgical intervention. The patient should be investigated for any coexisting metabolic bone disorders before proceeding with surgical intervention. The excision biopsy of such a specimen has to be examined histopathologically to rule out any neoplastic etiology. We present an adult male with a painful lump over the tibial tuberosity and its management.

Defining the region of interest of the knee for perioperative volumetric assessment with a portable 3D scanner in orthopedic and trauma surgery

Background

The aim of this study was to characterize three regions of interest (ROI) around the knee with a portable 3D scanner (Artec 3D scanner EVA). Soft tissue topography assessment with an optimized, precise, and reproducible method may assist surgeons when managing soft tissue swelling in the post traumatic setting.

Methods

12 healthy volunteers (24 legs, 7 women, 5 man) were included in this study. The patient cohort showed a mean age of 27.1 years (SD±3), a mean weight of 70 kg (SD±13) and a mean height of 171 cm (SD±8.8). All scans were recorded by the same examiner in the same room and with the same scanner (Artec, 3 D scanner EVA). Three volume regions of interest (ROI) were defined: the distal femur (circumference measured between the of superior extent of the patella to 10 cm proximal), the knee joint (measured from the top of the patella to the tibial tuberosity) and the proximal tibia (tibial tuberosity to 10 cm distal).

Results

The mean volume of the right leg was 3.901 l (I. distal femur: 1.63 l, knee joint: 1.33 l, proximal tibia: 1.10 l) and mean volume of the left leg was 3.910 l (I. distal femur: 1.66 l, knee joint: 1.34 l, proximal tibia: 1.12 l). The volume difference between the right and left leg was 0.094 l (SD ± 0.083 l) The Wilcoxon-Mann-Whitney test showed no significant differences of the volumes between the right and left leg.

Conclusions

This study demonstrates that portable 3D scanning could be an accurate and reliable tool for orthopedics and trauma surgeons. Based on the ROIs of this pilot study, further studies are needed to test the significance for clinical applications for patients with an injured knee.

Unusual Presentation of Extensor Tendon Rupture Caused by a Dorsal Wrist Synovial Cyst

Synovial cysts are juxta-articular-fluid–filled collections that are lined by synovial cells, distinguishing them from a very close cystic lesion, which is the ganglion cyst. They usually present with pain and unpleasant appearance; here we present a case of wrist synovial cyst that caused extensor tendon rupture. A 50-year-old woman presented to our clinic with a cystic lesion on the dorsum of her wrist, with an inability to extend her index finger. The lesion was found intraoperatively engulfing the extensors of the index and causing a rupture. The cyst was excised and the tendon was reconstructed; pathology report confirmed the lesion as synovial cyst. Synovial cysts and ganglion cysts are two different entities but they have been used interchangeably in the literature; pathology is the only way to differentiate between them because they usually present with identical scenarios. None of them were reported to cause extensor tendon rupture, as presented in our article. Synovial cysts can cause rupture to extensor tendons if they arise from the sheath, and it is better to anticipate synovial cyst and remove it surgically before causing any further damage, if the lesion appeared to rise from the tendon sheath on further imaging.

Morel-Lavallée Lesion of the knee after low-energy impact in a healthy non-athlete

BACKGROUND AND OBJECTIVE

Morel-Lavallée Lesion (MLL) of the knee is an uncommon cause of knee swelling usually due to high-energy impact or in patients on anticoagulation. MLL of the knee due to low-energy non-athletic associated trauma in patients without antithrombotic therapy is rare. Early diagnosis can be achieved using point-of-care ultrasound.

CASE REPORT

A 60-year-old female who was previously well was referred to our center for a persistently swollen left knee 2 months after a fall while on a flight of stairs. A point-of-care ultrasound identified a possible MLL of the knee. This was subsequently confirmed on magnetic resonance imaging (MRI). The lesion resolved with ultrasound-guided therapeutic aspiration.

CONCLUSION

MLL of the knee should be a differential diagnosis of traumatic knee swelling, even in low-energy trauma and in patients without bleeding diatheses. Ultrasound is a readily available and rapid modality that can aid both in the diagnosis and management of such lesions.

Magnetic resonance imaging of the knee

Knee pain is frequently seen in patients of all ages, with a wide range of possible aetiologies. Magnetic resonance imaging (MRI) of the knee is a common diagnostic examination performed for detecting and characterising acute and chronic internal derangement injuries of the knee and helps guide patient management. This article reviews the current clinical practice of MRI evaluation and interpretation of meniscal, ligamentous, cartilaginous, and synovial disorders within the knee that are commonly encountered.

Radiographic/MR Imaging Correlation of Soft Tissues

MR imaging is nowadays regarded as the preferred imaging modality for evaluation of soft tissue lesions. As plain radiographs are often the first step in evaluation of musculoskeletal disorders, identification of subtle soft tissue signs may be helpful to select patients who need to be referred for subsequent MR imaging. Although not very sensitive, certain plain film findings, such as intralesional calcification or gas, may allow one to make to a more specific tissue diagnosis and may obviate the need for invasive diagnostic procedures and potential harmful treatment.

Sonographic assessment of the anatomy and common pathologies of clinically important bursae

High-resolution ultrasonography has many advantages in the imaging of the musculoskeletal system, when compared to other imaging methods, particularly in superficial, easily accessible parts of the body. It is a perfect diagnostic tool for visualizing the most common pathologies of the musculoskeletal system, including the bursae. Inflammation of bursae is frequent, and it can mimic other diseases of the musculoskeletal system. Therefore, knowledge of normal ultrasound anatomy of the bursae, their exact location in the human body, and the sonographic signs of their most common pathologies is essential for establishing a quick and accurate diagnosis by ultrasound. Common conditions affecting bursae, leading to bursitis, include acute trauma, overuse syndromes, degenerative diseases, inflammatory conditions (rheumatoid arthritis, psoriatic arthritis, gout etc.), infections such as tuberculosis, synovial tumors and tumor-like conditions (pigmented villonodular synovitis, osteochondromatosis), and many more. This review article presents and explains ultrasound examples of the most frequent pathological conditions affecting bursae. Images include normal and pathological conditions of bursae around the shoulder joint, elbow, hip, knee, and ankle joint.

Evaluation of Knees in Asymptomatic Amateur Ice Hockey Players Using 3.0-T Magnetic Resonance Imaging: A Case-Control Study

Background:

Research on the changes to knee structures in asymptomatic amateur ice hockey players (AAIHPs) has been limited. We aimed to assess the performance of the knees in AAIHPs using 3.0-T magnetic resonance imaging (MRI).

Methods:

A total of 71 asymptomatic knees (32 AAIHPs and 39 age- and sex-matched controls) were imaged using a 3.0-T MRI scanner at the Affiliated Zhongshan Hospital of Dalian University in April 2017. Two experienced musculoskeletal radiologists were blinded to assess all MRI findings, including bursae around the knee, bone marrow edema (BME), meniscal signal changes, and articular cartilage and ligament damage. Any disagreements were resolved by a third professor of musculoskeletal radiology. Categorical variables were compared using the Chi-square test and continuous variables using the Student's t-test or Mann-Whitney U-test.

Results:

The most common finding was fluid-filled bursae surrounding the knee. In the AAIHP group, which totaled 32 knees and 416 bursae, 155 (37%) fluid-filled bursae were present. In the control group, there were a total of 39 knees and 507 bursae, and 91 (18%) fluid-filled bursae were present. There was a significant difference in the number of fluid-filled bursae between the two groups (P < 0.05). However, in AAIHPs, the prevalence of meniscal signal changes (16 knees, 50%) was higher than in the control group (2 knees, 5%; P < 0.001). Importantly, 15 of the 19 were grade II signals. Other changes were only found in AAIHPs. Articular cartilage lesions were detected in 47% of their knees, predominantly at the patellofemoral joint, and BME was found in 34% of their knees.

Conclusion:

The MRI findings of knees in AAIHPs mainly manifested as self-protection reaction, and proper ice hockey exercise could be advocated.

Ultrasound evaluation of bursae: anatomy and pathological appearances

A bursa is an extra-articular sac that may communicate with a joint and functions to decrease friction between tendons and either bone or skin. Bursae can be classified as native and non-native (adventitious) bursae. The native bursae are lined with a synovial membrane and occur at predictable anatomical sites; knowledge of these normal structures can help distinguish them from other pathological entities. An adventitious bursa can form at sites of friction rather than at predictable anatomical sites, but otherwise have imaging features similar to native bursae. Bursal distention can occur from many pathological processes, most commonly resulting from chronic overuse injury. When imaging bursal pathological conditions, there is often an overlap of imaging findings, regardless of the cause. In general, ultrasound of a distended bursa reveals a fluid collection with either simple anechoic or more complex hypoechoic fluid. Bursal distention is characteristically unilocular and compressible, unlike other structures such as ganglion cysts, which are usually multilocular and non-compressible. This article reviews the anatomical locations of common bursae and shows pathological examples using ultrasound. Knowledge of typical locations and imaging appearances of bursae can aid in narrowing the differential diagnosis and guiding further management and treatment decisions.

Common Mistakes and Pitfalls in Magnetic Resonance Imaging of the Knee

This pictorial review presents an overview of common interpretation errors and pitfalls in magnetic resonance imaging (MRI) of the knee. Instead of being exhaustive, we will emphasize those pitfalls that are most commonly encountered by young residents or less experienced radiologists.

Ultrasound of the Gruberi Bursa With Cadaveric and MRI Correlation

OBJECTIVE

The purpose of this study was to describe the appearance and ultrasound characteristics of the Gruberi bursa using a cadaveric model and retrospective ultrasound imaging review.

MATERIALS AND METHODS

For the cadaveric study, ultrasound of the dorsolateral ankle of a foot-ankle specimen was performed and was followed by injection of latex between the extensor digitorum longus (EDL) tendons and the talus and dissection. For the ultrasound imaging review, the radiology database was searched for ultrasound studies performed from September 15, 2000, through April 1, 2015, to identify subjects with a dorsolateral foot or ankle fluid collection detected on ultrasound. Images were retrospectively reviewed to characterize the location and size of the fluid collection, assess for the number of locules, and evaluate the compressibility of the fluid collection. It was determined whether the ultrasound findings were significantly different from chance: CI and p values were obtained from performing a test for one proportion.

RESULTS

Dissection of a cadaveric specimen revealed latex within a well-defined region between the EDL tendons and the dorsolateral talus; this location is consistent with a Gruberi bursa. For the image review, the imaging examinations of 162 subjects (age range, 16-88 years; 31 male subjects and 131 female subjects) were reviewed. On the ultrasound images, a fluid collection with its epicenter between the dorsolateral talus and EDL was found in 93% of ankles. Of the fluid collections identified on ultrasound, 98% were unilocular and 94% were anechoic. Of these fluid collections, 133 were assessed for compressibility, and 89% were compressible. The positive findings for a Gruberi bursa that were different from chance (p < 0.0001) were a fluid collection being located between the EDL tendons and the dorsolateral talus and being unilocular, anechoic, and compressible.

CONCLUSION

The Gruberi bursa characteristically is located between the EDL and the talus; on ultrasound, the Gruberi bursa is most commonly unilocular, anechoic, and compressible.

Hoffa's fat pad abnormalities, knee pain and magnetic resonance imaging in daily practice

Hoffa's (infrapatellar) fat pad (HFP) is one of the knee fat pads interposed between the joint capsule and the synovium. Located posterior to patellar tendon and anterior to the capsule, the HFP is richly innervated and, therefore, one of the sources of anterior knee pain. Repetitive local microtraumas, impingement, and surgery causing local bleeding and inflammation are the most frequent causes of HFP pain and can lead to a variety of arthrofibrotic lesions. In addition, the HFP may be secondarily involved to menisci and ligaments disorders, injuries of the patellar tendon and synovial disorders. Patients with oedema or abnormalities of the HFP on magnetic resonance imaging (MRI) are often symptomatic; however, these changes can also be seen in asymptomatic patients. Radiologists should be cautious in emphasising abnormalities of HFP since they do not always cause pain and/or difficulty in walking and, therefore, do not require therapy. Teaching Points • Hoffa's fat pad (HFP) is richly innervated and, therefore, a source of anterior knee pain. • HFP disorders are related to traumas, involvement from adjacent disorders and masses. • Patients with abnormalities of the HFP on MRI are often but not always symptomatic. • Radiologists should be cautious in emphasising abnormalities of HFP.

Knee bursitis: a sonographic evaluation

OBJECTIVE

To evaluate the use of ultrasound for the diagnosis of knee bursitis.

MATERIALS AND METHODS

One-hundred and fifty-eight patients who, from May 2013 to May 2014, had an ultrasound examination of the knee and magnetic resonance imaging (MRI) of the knee during the following month were eligible for the study. The exams were reviewed by two musculoskeletal radiologists with 20 years of experience.

RESULTS

Of these patients, 15 (7 men, 8 women) had bursitis, while 143 (76 men, 67 women) had no bursitis. In evaluating knee bursitis, US, when compared to MRI, correctly identified 13 out of 15 cases of bursitis, showing a sensitivity of 86.67 %, specificity 100 %, and K index of 0.92. Particularly in the suprapatellar bursa, ultrasound showed bursitis in 5 cases versus 7 by MRI (sensitivity of 71.4 %, specificity of 100 %, and K index of 0.82).

CONCLUSION

Ultrasound can be used as a valuable tool for the evaluation of bursitis of the superficial bursae in patients who cannot undergo MRI.