Giant cell tumor of the distal phalanx of the biphalangeal fifth toe: a case report and review of the literature.

Giant cell tumor of the distal phalanx of a toe is rather unusual. We report an unusual case of giant cell tumor arising at the distal phalanx of the left biphalangeal fifth toe in a 13-year-old boy. This was treated successfully with curettage and packing with bone substitution.

Lateral ankle ligaments: MR arthrography with anatomic correlation in cadavers.

OBJECTIVE: The purpose of our study was to use magnetic resonance (MR) imaging and MR arthrography to demonstrate the anatomy of the lateral ankle ligaments using standard and oblique imaging planes in cadavers. MATERIAL AND METHODS: MR imaging of ten cadaveric ankles was performed before and after intra-articular administration of contrast solution. Proton-density MR images were acquired in standard and oblique imaging planes. MR imaging was correlated with anatomic sections. Measurements using oblique imaging planes were obtained to characterize the morphology of the lateral ligaments. RESULTS: The anterior talofibular ligament (ATFL) had a variable number of bands in all specimens, separated by fat signal oriented obliquely parallel to the long axis of the ligament. The fibular attachment of ATFL was located in close proximity to the fibular attachment of the distal band of the anterior tibiofibular ligament (AITFL). The angle formed by the calcaneofibular ligament (CFL) and the fibular shaft varied with different ankle positions. Special axial oblique plane best demonstrated the CFL. The posterior talofibular ligament (PTFL) was multi-fasciculated in appearance. Dorsiflexion of the ankle joint helped elongate the PTFL and best depicted this ligament in its entirety in the axial plane. CONCLUSION: Oblique imaging planes parallel to the long axis of the individual ligaments may improve visualization of the anatomy of the lateral ankle ligaments. The orientation of the lateral ankle ligaments is affected by the position of the talocrural and subtalar joints. Understanding the morphology of the lateral ankle ligaments can help radiologists diagnose abnormalities of these ligaments.

Tibiofibular syndesmotic ligaments: MR arthrography in cadavers with anatomic correlation.

PURPOSE: To use magnetic resonance (MR) imaging and MR arthrography to characterize the normal anatomy of the tibiofibular syndesmotic ligaments with standard and oblique imaging planes in cadavers. MATERIALS AND METHODS: Ten cadaveric ankle specimens were obtained and used in accordance with institutional and HIPAA guidelines, and informed consent for research was obtained from relatives of the deceased. MR imaging was performed before and after intraarticular administration of contrast material. Proton-density-weighted MR images were correlated with anatomic slices. RESULTS: The anterior inferior tibiofibular ligament (AITFL) had a variable number of bands in all specimens. A separate distal band was identified in all specimens, revealing a more horizontal course than other components of the AITFL and attaching more medially to the anterior margin of the tibial plafond. The posterior inferior tibiofibular ligament (PITFL) and inferior transverse ligament were best seen in coronal oblique planes. The posterior intermalleolar ligament was observed in all specimens and had a variable appearance that ranged from a thin strand to a thick cord. The interosseous ligament (IOL) coursed obliquely to attach proximally to the tibia and insert distally in the fibula. This ligament was fenestrated with separate anterior and posterior fibers. The anterior fibers were more proximal, and the posterior fibers were more distal, attaching to the fibula in close proximity to the PITFL. Coronal images best depicted the course of the IOL. CONCLUSION: Oblique imaging planes parallel to the long axis of the ligament better display the normal anatomy of the tibiofibular syndesmotic ligaments when compared with standard imaging planes. (c) RSNA, 2010.

Acetabulum protrusio and center edge angle: new MR-imaging measurement criteria--a correlative study with measurement derived from conventional radiography.

OBJECTIVE: The goal of this study was to identify a method of measurement for acetabulum protrusio and center edge angle (CEA) using MR imaging of the pelvis that correlated with classic methods using radiographic landmarks. MATERIALS AND METHODS: MR images and radiographs of the pelvis in 67 patients (132 hips) were used to identify reliable MR-imaging methods for measuring protrusio acetabulum and CEA that correlated strongly with established radiographic measurements. Protrusio acetabulum was determined using the radiographic criterion that the acetabular line projects medial to the ilioischial line by 3 mm or more in men and 6 mm or more in women. Pearson correlation factor was used to determine inter-observer variability and those methods that demonstrated the strongest correlation. The mean and standard deviation of MR-imaging and radiographic measurements for both the normal and protrusio hips were established. RESULTS: Several MR methods correlated strongly with radiographic measurements. The preferred method employed axial MR images at the level of the ischial spine with measurement of the distance between the medial most point of the acetabular fossa and a line perpendicular to the horizontal axis that passed through the lateral margin of the posterior inner pelvic wall. The Pearson's correlation factor between radiographic and MR measurements using this method was 0.84, and inter-observer correlation was 0.80. There were 126 hips in 63 patients (17 female and 44 male) that did not meet the radiographic criteria for protrusio acetabula. In this group of normal hips, the mean and standard deviation of radiographic measurements were 1.9 and 2.8 mm in male patients and -0.5 and 1.7 mm in female patients, and the mean and standard deviation for the preferred MR method was 1.3 and 2.5 mm in male patients and -0.8 and 1.9 mm in female patients. A total of six hips in four patients (two female and two male) met the radiographic criteria for protrusio acetabula. In this group of patients, the mean and standard deviation of radiographic measurements were -3.7 and 1 mm in male patients and -5.4 and 0.9 mm in female patients, and the mean and standard deviation for the preferred MR method was -4.1 and 0.4 mm in male patients and -6.5 and 0.3 mm in female patients. Our study also showed that the CEA was best measured using anterior to middle coronal MR images. Posterior coronal MR-imaging measurements correlated poorly with radiographic measurements. CONCLUSION: MR imaging can be used to assess acetabular morphology and measure acetabulum protrusio.