The imaging findings of impingement syndromes of the lower limb.

In this article we provide an overview of impingement syndromes of the lower limb. At the level of the hip, femoroacetabular and ischiofemoral impingement are recognised. At the level of the knee, we discuss Hoffa's fat pad impingement, suprapatellar fat pad impingement, pericruciate impingement, and iliotibial band syndrome. The impingement syndromes associated with anterior cruciate ligament (ACL) repair and intercondylar osteophytes are also illustrated. Most impingement syndromes are described at the level of the ankle. These include, anterior, anterolateral, posterior, anteromedial, posterior, and posterolateral impingement. For these conditions, we describe the best technique and expected imaging findings. It should be kept in mind that many of these findings have been observed in the asymptomatic population. Impingement is essentially a clinical diagnosis and imaging findings should be considered as supportive elements for this clinical diagnosis.

Comparison of the anatomical dimensions and mechanical properties of the dorsoradial and anterior oblique ligaments of the trapeziometacarpal joint.

PURPOSE: The respective roles of the dorsoradial (DRL) and anterior oblique (AOL) ligaments in stability of the highly mobile trapeziometacarpal (TMC) joint remain disputed. Earlier publications have pointed to the AOL as the key stabilizing structure; yet, more recent publications have challenged the stabilizing role of the AOL, favoring the DRL as the main TMC joint stabilizer. We executed an anatomical study of the ligaments, including detailed dissection to quantify the length, width, and thickness of the AOL and DRL and tested the material properties of these ligaments. METHODS: Thirteen fresh frozen cadaveric thumbs from 9 specimens were used. Length, width, and thickness of the AOL and DRL were measured on magnetic resonance imaging and/or after dissection. Next, the first metacarpal and trapezium were isolated together with both ligaments, and both bones were cut sagittally to isolate a first metacarpal-AOL-trapezium and first metacarpal-DRL-trapezium complex from each thumb. These samples were subjected to cyclic loading in displacement-controlled tests. The obtained force-displacement curves were used to calculate stiffness and hysteresis of each sample. RESULTS: Our results showed that the DRL is significantly shorter and thicker than the AOL, which is thin and ill-defined. Our results also indicate that the DRL has a higher stiffness than the AOL, making it a more likely candidate to provide joint stability. CONCLUSIONS: Although the AOL has been asserted to be the primary restraint to dorsoradial subluxation, this view has been challenged over the past 10 years by several studies. These studies have shown the AOL to be relatively weak and compliant compared with the intermetacarpal and dorsoradial ligaments and have demonstrated that the DRL is the strongest and stiffest ligament of the TMC joint. Our studies confirm these findings. CLINICAL RELEVANCE: This study indicates that the DRL is relatively stiff and thick, suggesting it should be repaired or reconstructed when disrupted to restore stability of the TMC joint.

Rapid malignant transformation of primary synovial chondromatosis into chondrosarcoma.

Chondrosarcoma of the synovium is rare. It may arise de novo from the synovium or pre-existing synovial chondro- matosis may undergo malignant transformation into chondrosarcoma. Diagnosing a malignant transformation of the synovium remains a big challenge. It is based on the correlation of clinical findings, imaging and histology, as illustrated in this case report.

A bare area of the glenoid misdiagnosed as a cartilage ulceration.

We report on a 17-year-old girl who developed shoulder pain after a fall on an outstretched arm. CT arthrography and MR imaging demonstrated a cartilage defect centrally located in the glenoid. This was accompanied by an eroded appearance of the underlying bone. Since symptoms persisted over several months it was initially thought this represented a cartilage injury. Subsequently arthroscopy was performed and the abnormality was identified as a bare area of the glenoid. A tear of the superior glenohumeral ligament was depicted and was repaired. The bare area is an oval area denuded of cartilage that is probably developmental and that should be differentiated from true cartilage injuries to avoid unnecessary interventions. An eroded appearance of the underlying bone may occur on imaging, a finding that has not been previously reported.

An unusual cause of subtalar pain and instability: accessory calcaneus.

We report on a 45-yr-old male sports instructor with chronic pain and instability of the ankle. He was a recreational basketball player, but because of repeated ankle sprains and chronic subtalar pain this activity became impossible. The radiologic findings were compatible with the diagnosis of accessory calcaneus. In an initial therapeutic approach the patient was treated conservatively with taping and physical therapy, but this failed to relieve the symptoms. Next, a ligamentoplasty was performed. The instability improved, but the pain remained the same. Finally the accessory calcaneus was resected and short term follow-up was unremarkable. Accessory calcaneus is an uncommon anatomical variation that may cause subtalar pain and instability. Resection of the accessory bone may be necessary to provide relief of symptoms. Accessory calcaneus can be well demonstrated on CT, SPECT-CT, and MR. MR and nuclear medicine can indicate instability of the accessory bone by showing bone marrow edema on MR or uptake on fusion imaging.

Magnetic resonance imaging of anatomical variants of the subtalar joint.

OBJECTIVE: To evaluate MRI with thin slices to depict anatomical variations of the subtalar and talocalcaneonavicular joints. METHODS AND MATERIALS: Ankle MRI was performed in 51 patients. The articular configurations were differentiated on sagittal T1-weighted and three-dimensional (3D) DESS images. Multiplanar reconstructions were performed. The variation in curvature of the posterior facet of the calcaneus and talus was analysed. 3D surface-rendered images of the calcaneus were obtained. All images were studied by an experienced physical therapist. RESULTS: Analysis revealed that 18 (36.7%) of the subjects had 3 distinct facets on the calcaneus. A missing anterior facet was revealed in five (10.2%) of subjects. Twenty-six (53.1%) subjects showed a fusion of the anterior and middle facets. In four cases, an articulation was found between the talus and the cuboid bone. At the posterior talocalcaneal articulation, variations were observed of the curvature of the medial side of the joint. CONCLUSIONS: The configuration of the facets of the talocalcaneal joints can be analysed on MR images. On 3D images, an articular connection was seen between the talus and the cuboid bone, as well as variations in the curvature of the posterior talocalcaneal joint. These anatomical variations may have implications for mobility and stability of the ankle.

MR imaging of normal extrinsic wrist ligaments using thin slices with clinical and surgical correlation.

Eighty-nine MR examinations of the wrist were retrospectively analyzed. MRI results were compared with clinical findings and/or arthroscopy. Thin proton density and T2 weighted sequences and 3D DESS weighted sequences were applied on a 1.5T scanner. On the palmar side three radiocarpal ligaments are recognized including the radioscaphocapitate, radiolunotriquetral, radioscapholunate, and midcarpal triquetroscaphoidal ligaments. Ulnocarpal ligaments include the ulnolunate ligament and the ulnotriquetral ligament. On the dorsal side three ligaments are recognized: the dorsal radiolunotriquetral, and the midcarpal triquetroscaphoidal and triquetro-trapezoido-trapezial. The collateral ligaments include the radial and ulnar collateral ligament. MR is a valuable technique in the assessment of the extrinsic and midcarpal ligaments. Depiction of the extrinsic ligaments can best be accomplished with coronal 3D DESS sequences and sagittal and transverse proton density and T2 weighted sequences with thin slices.

Pigmented villonodular synovitis of the midfoot.

A 60-year-old man presented with a longstanding slowly growing swelling at the dorsal aspect of the left midfoot. The lesion was imaged with CT, ultrasound, and MR. On CT bony erosions were evident. On MR the lesions appeared bifocal and one component was hypointense on T2 weighted images suggesting hemosiderin deposits. The other component was hyperintense on T2 which is more unusual for PVNS. Imaging findings, however, suggested PVNS which was pathologically confirmed. A unique finding in this case is the late age of presentation of the disorder. Also the bifocal nature of the lesion is relatively uncommon.

MRI spectrum of medial collateral ligament injuries and pitfalls in diagnosis.

The medial collateral ligament (MCL) is made up of different components and spans the medial aspect of the knee. With injuries the superficial or deep and posterior components may be involved. A variety of conditions including MCL bursitis, medial osteoarthritis, medial cellulitis, medial bursitis, medial meniscal cyst, meniscocapsular separation, and retinacular tear may present with high signal surrounding the MCL fibers and simulate an MCL tear.

The talocalcaneal unit: pictorial review of anatomy and pathologic conditions on multi detector CT.

Normal anatomy of the subtalar joints is illustrated in cadaveric specimens. Variations of the subtalar joints include three facets, fused middle and anterior facet, and missing anterior facet. Patients were studied by means of Multi Detector Computed Tomography (MDCT) to provide clinical examples of subtalar pathology including traumatic and non traumatic disorders.

Tuberculous arthritis of the finger: a forgotten disease.

We present a case of a 64-year-old man from Belgian origin with a chronic painful swelling of the third finger. A chronic arthritis from atypical germ was suspected at the third metacarpo-phalangeal joint on the plain radiography, ultrasonography and MR examination. A few months later, he developed thoracic back pain. Plain radiographs, a Technetium-99m bone scan and MR examination of the thoracic spine revealed a spondylodiscitis of the dorsal spine. A tuberculous origin was found on the biopsy of the affected dorsal vertebral bodies D9 and D10 as suspected on the first imaging examinations of the finger. Besides the patient was found to be HIV-positive. This case shows that it is important to think of musculoskeletal tuberculosis particularly in high-risk persons because if left untreated, it can be devastating.

A pictorial overview of ultrasound of tendon disorders.

A variety of terms that is often confusing is used to describe tendon changes at ultrasound.The classification of tendon disorders is often based on a combination of clinical and imaging findings. We present an overview of different categories of tendon disorders where ultrasound may contribute to the diagnosis and classification. We suggest the following categories: overuse, traumatic, inflammatory, and metabolic.The differentiation is not always possible and the importance of clinical data must be taken into account.The spectrum of tendon abnormalities is illustrated with clinical examples.

MRI of cartilage and subchondral bone injury. A pictorial review.

In this article, we present an overview of various cartilage and subchondral bone abnormalities seen on MRI. Injury of bone is often associated with cartilage damage and vice versa. A number of common conditions affecting joints typically show certain combinations of chondral and subchondral changes.

The effectiveness of diagnostic imaging methods for the assessment of soft tissue and articular disorders of the shoulder and elbow.

There are no clear guidelines for diagnostic imaging of articular and soft tissue pathologies of the shoulder and elbow. Several methods are used, including magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA) and ultrasound (US). Their cost-effectiveness is still unclear. We performed a meta-analysis of the relevant literature and discussed the role of MR imaging of the shoulder and elbow compared with other diagnostic imaging modalities. For the shoulder impingement syndrome and rotator cuff tears, MRI and US have a comparable accuracy for detection of full-thickness rotator cuff tears. MRA and US might be more accurate for the detection of partial-thickness tears than MRI. Given the large difference in cost of MR and US, ultrasound may be the most cost-effective diagnostic method for identification of full-thickness tears in a specialist hospital setting (Evidence level 3). Both MRA and CT arthrography (CTA) are effective methods for the detection of labrum tears. More recently, multidetector CTA has offered the advantages of thinner slices than with MRA in a shorter examination time. Still, MRA has the advantage towards CTA to directly visualize the affected structures with a better evaluation of extent and location and to detect associated capsuloligamentous injuries. For the elbow pathologies, plain MRI or MRA have the advantage towards CTA to detect occult bone injuries. CTA is better for the assessment of the thin cartilage of the elbow. Both US and MRI are reliable methods to detect chronic epicondylitis; US is more available and far more cost-effective (Evidence level 2). MRA can differentiate complete from partial tears of the medial collateral ligament. US or MRI can detect partial and complete biceps tendon tears and/or bursitis. MRI can provide important diagnostic information in lesions of the ulnar, radial, or median nerve.

An unusual case of cat-scratch disease of the knee: case report and differential diagnosis.

We present a case of a 16-year-old boy with a painful swelling in the popliteal fossa, slight fever, articular and muscle pain of 3 weeks duration. Plain radiography and MR examination were performed in order to characterize the lesion. Additionally to the poorly defined mass, 2 satellite nodules were shown. Subsequent biopsy revealed a granulomatous process and 2 satellite lymphadenopathies highly suggestive of cat-scratch disease. This case shows that the differential diagnosis of a soft tissue mass of the knee should not only include tumoral processes or pseudotumoral lesions, but also granulomas from infectious or non-infectious origin. Knowledge of the patients contact with cats and the detection of skin scratches is usually the clue to the correct diagnosis.

MR imaging findings in patients with a surgically significant mediopatellar plica.

PURPOSE: To identify MR imaging findings seen in patients with an arthroscopically confirmed significant plica. MATERIALS AND METHODS: MR and arthroscopy reports of 450 patients were reviewed. Nine patients were identified with an arthroscopically significant plica that was resected. Nine patients from these 450 were randomly chosen as a control group. Different criteria were evaluated on the MR images of all patients including: interposition of plica, number of slices with interposition, presence of fluid (focal or generalized), and thickening of the plica. RESULTS: Interposition was found on 3 to 10 transverse imaging slices in the study group (mean, 5.9), and 1 to 4 imaging slices in the control group (mean, 3). Thickening was present in 4/9 patients of the study group and 2/9 patients in the control group. Focal fluid, out of proportion to fluid in the remainder of the joint was found in all patients of the study group and in none of the control group. CONCLUSION: Interposition of the plica on more than 5 transverse slices, and focal fluid adjacent to the plica may suggest the presence of a plica that will be considered significant at arthroscopy.

Proceedings of the SRBR-KBVR osteoarticular section meeting of June 29, 2004 in Antwerp. Cystic adventitial disease.

The purpose of this paper is to give a short review of the pathogenesis, imaging characteristics, differential diagnosis and current treatment of cystic adventitial disease.