Ultrasound-guided aspiration in suspected sepsis of resection arthroplasty of the hip joint

Common sonographic findings in the painful hip after hip arthroplasty

Diagnosing the cause of hip pain in patients with hip arthroplasty can be challenging because of the numerous possible causes of pain and artifacts caused by the prosthetic components on computed tomography and magnetic resonance imaging. Sonography plays an important role in the diagnosis and management of these patients because the soft tissues surrounding the prosthetic joint are not obscured by artifacts and because sonography enables hands-on examination of the painful site, dynamic evaluation of moving structures, and comparison with the opposite side. Another advantage of sonography is the ability to perform sonographically guided diagnostic and therapeutic procedures. In this pictorial essay, we highlight commonly encountered sonographic findings in patients with hip pain after hip arthroplasty.

Validity of preoperative ultrasound-guided aspiration in the revision of hip prosthesis

Preoperative diagnosis of septic loosening hip prosthesis is often challenging. Culture test on joint samples obtained during revision surgery is the diagnostic gold standard while the role of preoperative hip aspiration is still controversial. The aims of this prospective randomized study were to compare the sensitivity, specificity and accuracy of preoperative ultrasound-guided and fluoroscopic-guided aspiration, and to identify associated laboratory parameters or scintigraphy that could help in predicting septic loosing hip prosthesis. Sixty patients affected by persistent pain after hip prosthesis randomly received fluoroscopic-guided or ultrasound-guided hip aspiration before revision surgery. The results of culture tests of joint fluid presurgically and at surgery were compared. In addition, associated blood inflammatory markers and scintigraphy were evaluated. Ultrasound-guided aspiration showed a better sensitivity (69% vs. 27%), specificity (94% vs. 75%) and accuracy (83% vs. 40%) than fluoroscopic-guided aspiration. The combination of ultrasound-guided aspiration and C-reactive protein represents the best model to predict septic loosening hip prosthesis preoperatively.

Comparison of infection rates among ultrasound-guided versus traditionally placed peripheral intravenous lines

OBJECTIVE

The purpose of this study was to compare infection rates of peripheral intravenous (IV) lines placed under ultrasound guidance with traditionally placed IV lines.

METHODS

We conducted a retrospective review of emergency department (ED) and hospital records of adult patients who had a peripheral IV line placed in the ED and were admitted to the hospital over a 1-year period. This study took place at a level I academic urban ED with an annual census of 75,000. All admitted patients with a peripheral IV placed under ultrasound guidance in the ED were identified. Control patients had a traditional landmark approach. Emergency department nurses followed standard aseptic precautions when inserting both ultrasound-guided as well as traditionally placed IV lines. Researchers reviewed all parts of the medical record, including ED and inpatient notes. Descriptive statistics and chi(2) and Fisher exact tests were used in data evaluation.

RESULTS

A total of 402 patients who had peripheral IV lines placed under ultrasound guidance were compared with 402 matched control patients. In the ultrasound-guided IV group, the mean time between insertion to catheter removal was 2.6 days compared with 2.4 days in the traditional group (P = .03). There were 2 documented infections in the ultrasound group and 3 in the traditional group, yielding infection rates of 5.2 per 1000 in the ultrasound-guided IV group and 7.8 per 1000 in the traditional approach group. There was no statistically significant difference between infection rates in the two groups (P = .68).

CONCLUSIONS

Both traditional and ultrasound-guided approaches had low infection rates, suggesting that there is no increased risk of infection with ultrasound guidance for peripheral IV lines.

Role of ultrasound in musculoskeletal infections

Ultrasound is able to play a key role in the management of musculoskeletal soft tissue infections. It is an easily accessible imaging modality that can be used immediately after plain radiographs have been obtained. Quick diagnosis is essential in the clinical setting of musculoskeletal infection because delay can lead to significant morbidity. In addition to its diagnostic capabilities, US offers a safe, real-time, and convenient technique to perform immediately a guided-needle aspiration of any suspicious fluid collection. US provides the most efficient way to document quickly an infection of the musculoskeletal soft tissues and to identify the offending micro-organism.

Magnetic resonance imaging-guided focused ultrasound synovectomy

OBJECTIVE

To investigate the feasibility of magnetic resonance imaging (MRI)-guided high power focused ultrasound (FUS) to perform synovectomy noninvasively.

METHODS

Five New Zealand white male rabbit knees with experimentally induced arthritis underwent MRI-guided thermal surgery by high power (60 W/10 s) sonication. Evidence of tissue coagulation was monitored during the procedure and confirmed by gross and microscopic evaluation and MRI.

RESULTS

Partial synovectomy was performed in five animals. Necrotized synovial tissue was observed on gross and microscopic evaluation. Visible signal intensity alterations including high signal intensity on T2-weighted (T2W) images and lack of contrast-enhancement on T1-weighted (T1W) post-contrast, post-sonication images were characteristic and reproducible.

CONCLUSION

Our results demonstrate the ability of high power sonication to destroy synovial tissue in vivo.