Postoperative imaging of the ankle and foot

[Postoperative MRI of the ankle]

CLINICAL/METHODICAL ISSUE

Postoperative imaging of the ankle can be challenging, even for the experienced radiologist. Pathological and postoperative changes to the primarily complex anatomy of the ankle with its great variety of bone structures, tendons, ligaments, and soft tissue in a very limited space may cause great difficulty in differentiating underlying pathology from expected postoperative changes and artifacts, especially in magnetic resonance imaging (MRI).

STANDARD RADIOLOGICAL METHODS

Selecting the appropriate radiological modality is key to making the correct diagnosis. Therefore, knowledge of the initial and current symptoms is just as important as familiarity with the most frequently performed operations in the ankle.

PRACTICAL RECOMMENDATIONS

This article aims to give its reader a summary of the most important and frequently performed operation techniques of the ankle and discusses the expected appearance and possible complications in postoperative imaging.

Diagnostics in tarsal fusion: The theory and practise in The Netherlands

BACKGROUND

This study compares the preferences of Dutch orthopaedic surgeons for different diagnostic modalities in performing tarsal fusions versus consensus, evidence or expert opinion reported in the literature.

METHODS

A literature search of Medline was performed to obtain evidence-based information on various diagnostic tools. In addition, 89 registered Dutch foot and ankle surgeons were sent a questionnaire concerning the diagnostic modalities use in tarsal fusion.

RESULTS

Fifty-eight (65%) questionnaires were returned. The experienced surgeons measured outcomes significantly more often than other surgeons. Diagnostic injections were often used, although scant evidence exists in the literature. Postoperative diagnostics mainly consist of X-ray examination, although there is consensus in the literature that computed tomography is more accurate.

CONCLUSIONS

The study revealed some surprising discrepancies concerning the use of diagnostic imaging in tarsal fusion. More clinical research is needed to identify the most effective diagnostic imaging modalities so as to encourage their wider adoption.

Sonography of the Achilles Tendon After Complete Rupture Repair: What the Radiologist Should Know

This review aims to provide the radiologist with simple and systematic guidelines for evaluation of the Achilles tendon after complete rupture repair. Currently, there is a plethora of nonsurgical and surgical treatments, but sonographic examination has shown no significant differences between them. A systematic analysis of several parameters (morphologic characteristics, structure, color Doppler vascularization, and mobility) should be undertaken. Morphologically, the repaired tendon is larger, wider, or both. The loss of the fibrillary structure, inhomogeneity, and the surgical material in the context of the tendon are "normal" aspects after a repaired rupture. The presence of fluid collections when affecting greater than 50% of the surface of the tendon and extensive calcifications should be considered pathologic aspects. In the immediate postoperative period, there is the absence of vascularization detectable by color Doppler imaging. During the first 3 months, there is an increase in intratendinous vascularization with hypervascularization. From 3 to 6 months, stabilization and regression of the vascularization occur. Beyond the first 6 months, the hypervascularization is pathologic. The pattern of motion is, generally, reduced considerably more often in surgically treated tendons than in non-surgically treated ones. Elastography generally shows a hard appearance, with only a relatively heterogeneous pattern. In conclusion, a treated tendon will never regain a normal sonographic appearance, and the operator must distinguish between normal posttreatment changes and real pathologic characteristics.

Technical Considerations: Best Practices for MR Imaging of the Foot and Ankle

There are many challenges involved in obtaining diagnostic MR images of the foot and ankle. The complex anatomy and morphology, with curved and angular structures localized to the periphery of the body, make for an inherent challenge, let alone if an added level of complexity, such as orthopedic instrumentation, is added. This review outlines the technical considerations best designed to produce diagnostic images of the foot and ankle, with an emphasis on the postoperative state, including imaging in the presence of metal.

Usefulness of IDEAL T2-weighted FSE and SPGR imaging in reducing metallic artifacts in the postoperative ankles with metallic hardware

PURPOSE

The aim of this work is to prospectively compare the effectiveness of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL), T2-weighted fast spin-echo (FSE), and spoiled gradient-echo (SPGR) MR imaging to frequency selective fat suppression (FSFS) protocols for minimizing metallic artifacts in postoperative ankles with metallic hardware.

MATERIALS AND METHODS

The T2-weighted and SPGR imaging with IDEAL and FSFS were performed on 21 ankles of 21 patients with metallic hardware. Two musculoskeletal radiologists independently analyzed techniques for visualization of ankle ligaments and articular cartilage, uniformity of fat saturation, and relative size of the metallic artifacts. A paired t test was used for statistical comparisons of MR images between IDEAL and FSFS groups.

RESULTS

IDEAL T2-weighted FSE and SPGR images enabled significantly improved visualization of articular cartilage (p < 0.05), the size of metallic artifact (p < 0.05), and the uniformity of fat saturation (p < 0.05). However, no significant improvement was found in the visibility of ligaments.

CONCLUSIONS

IDEAL T2-weighted FSE and SPGR imaging effectively reduces the degree of tissue-obscuring artifacts produced by fixation hardware in ankle joints and improves image quality compared to FSFS T2-weighted FSE and SPGR imaging. However, visibility of ligaments was not improved using IDEAL imaging.

''Reappearance'' of a transferred flexor digitorum longus tendon fixed with a bioresorbable interference screw on postoperative MRI: case report

Level of Evidence: V, Expert Opinion