MR imaging-anatomical correlation of the metatarsophalangeal joint of the hallux: Ligaments, tendons, and muscles.

OBJECTIVE: To perform an MR imaging-anatomical correlation to elucidate the anatomy of muscles, tendons, and ligaments about the hallux as seen on MR imaging. MATERIALS AND METHODS: Four fresh and 4 embalmed cadaver specimens were used for this study. The embalmed specimens and one fresh specimen were dissected by three investigators. The fresh specimens were preserved deep frozen. They were thawed and imaged with a 3 T MR system. Proton density weighted images were obtained. The specimens were refrozen and sectioned with a band saw into 3 mm thick slices. RESULTS: Musculotendinous structures were equally well seen in the fresh and embalmed specimens. The capsular ligaments could best be studied in the fresh specimens. Proximal to the sesamoids the following muscle and tendon anatomy was delineated: the abductor hallucis tendon inserted on the medial sesamoid bone together with the medial belly of the flexor digitorum brevis; the adductor hallucis (transverse and oblique heads) inserted on the lateral sesamoid together with the lateral head of the flexor hallucis brevis. At the level of the sesamoid bones and distally, the ligaments making up the plantar plate were delineated, including the presesamoid band, the flexor hallucis longus pulley, the sesamometatarsal ligaments, the sesamophalangeal ligaments, and the capsular ligaments. CONCLUSION: MRI allows for accurate assessment of the complex anatomy of the hallux. At the level proximal to the sesamoids the muscle and tendon insertions are well demonstrated. At the level of the sesamoids and distally, the ligaments making up 'the plantar plate' are well demonstrated.

Morton Neuroma: Evaluated with Ultrasonography and MR Imaging

OBJECTIVE: The purpose of this study was to compare the diagnostic accuracy of both ultrasonography (US) and magnetic resonance imaging (MRI) for the assessment of Morton neuroma. MATERIALS AND METHODS: Our study group was comprised of 20 neuromas from 17 patients, and the neuromas were confirmed on surgery following evaluation with US, MRI, or both US and MRI. The diagnostic criterion for Morton neuroma, as examined by US, was the presence of a round or ovoid, well-defined, hypoechoic mass. The diagnostic criterion, based on MR imaging, was a well defined mass with intermediate to low signal intensity on both the T1- and T2-weighted images. The retrospective comparison between the sonographic and MR images was done by two experienced radiologists working in consensus with the surgical and pathologic correlations. RESULTS: The detection rate of Morton neuroma was 79% for 14 neuromas from 11 patients who had undergone US followed by an operation. The detection rate was 76% for 17 neuromas from 15 patients who had undergone MRI and a subsequent operation. The mean size of the examined neuromas was 4.9 mm on the US images and it was 5.1 mm on the MRI studies. Ten neuromas (71%) were 5 mm or less as measured by US, and three neuromas were not detected, whereas on the MRI analysis, 10 neuromas (59%) were 5 mm or less and four neuromas were not visualized. Among the patients examined during postoperative follow-up, symptoms were completely relieved in 85% and the symptoms were partially relieved in 15%. CONCLUSION: US and MR imaging are comparable modalities with high detection rate for the evaluation of Morton neuroma.

Naviculo-Medial Cuneiform Coalition: Radiological Features

PURPOSE: To define the radiological features of the naviculo-medial cuneiform coalition. MATERIALS AND METHODS: This study examined 35 feet from 25 patients (mean age 26 years) with a naviculo-medial cuneiform coalition. The images were analyzed retrospectively with regard to irregular articular surface, subchondral sclerosis, subchondral cyst, beak-like spur, the change in joint space, bony fusion seen on plain radiographs (n=35) and CT (n=14), and the histological type of coalition on MRI (n=3). The extent of joint involvement was also evaluated. RESULTS: Of the 35 feet, plain radiographs and/or CT showed an irregular articular surface in 34 (97.1%), subchondral sclerosis in 30 (85.7%), a subchondral cyst in 29 (82.9%), a beak-like spur in 23 (65.7%), a narrowing of the joint space in 24 (68.6%) and no bony fusions (0%). The T1-weighted images revealed low signal intensity, and the T2-weighted fast spin-echo and gradient images revealed high signal intensity in the three feet with a cartilaginous coalition. The coalition involved the plantar part of the joint in all 35 feet. CONCLUSION: The characteristic radiological features of a naviculo-medial cuneiform coalition include an irregular articular surface with possible secondary degenerative changes in the plantar margin of the joint, non-osseous type.

MR Imaging Findings of Painful Type II Accessory Navicular Bone: Correlation with Surgical and Pathologic Studies

OBJECTIVE: To evaluate the MR imaging findings of painful type II accessory navicular bone and to correlate these with the surgical and pathologic findings. MATERIALS AND METHODS: The MR images of 17 patients with medial foot pain and surgically proven type II accessory navicular abnormalities were reviewed. The changes of signal intensity in the accessory navicular, synchondrosis and adjacent soft tissue, the presence of synchondrosis widening, and posterior tibial tendon (PTT) pathology on the T1-weighted and fat-suppressed T2-weighted images were analyzed. The MR imaging findings were compared with the surgical and pathologic findings. RESULTS: The fat-suppressed T2-weighted images showed high signal intensity in the accessory navicular bones and synchondroses in all patients, and in the soft tissue in 11 (64.7%) of the 17 patients, as well as synchondrosis widening in 3 (17.6%) of the 17 patients. The MR images showed tendon pathology in 12 (75%) of the 16 patients with PTT dysfunction at surgery. The pathologic findings of 16 surgical specimens included areas of osteonecrosis with granulomatous inflammation, fibrosis and destruction of the cartilage cap. CONCLUSION: The MR imaging findings of painful type II accessory navicular bone are a persistent edema pattern in the accessory navicular bone and within the synchondrosis, indicating osteonecrosis, inflammation and destruction of the cartilage cap. Posterior tibial tendon dysfunction was clinically evident in most patients.

Malignant Schwannoma of the Great Toe: A Case Report

Malignant schwannomas arising from the peripheral nerve sheath of the foot are very rare. We encountered a case of malignant schwannoma of the great toe in a 60-year-old woman with painful swelling and exudative ulceration, and report the findings of MR imaging and review the literature.

MR Image Findings of Giant Cell Tumor of the Tendon Sheath Involving the Foot: A Case Report

Giant cell tumor of the tendon sheath(GCTTS) is a benign condition which involves the synovium of the tendonsheaths, and usually occurs around the small joints, e. g. the ankle, knee, and wrist. Histologically, GCTTS is similar to pigmented villonodular synovitis(PVNS). The authors report MRI findings of a GCTTS. This showed lower signal-intensity lesions than adjacent muscles on T1-weighted, proton density weighted, and T2-weighted images.