Introducing image-guided synovial aspiration and biopsy in assessing peri-prosthetic joint infection: an early single-centre experience.

AIM: Synovial sampling can be used in the diagnosis of peri-prosthetic joint infection (PJI). The purpose of this study was to establish the role of simultaneous image-guided synovial aspiration and biopsy (SAB) during an initial 2-year experience at our institution. METHODS: Retrospective review of consecutive SABs performed during 2014-2016 at a tertiary referral musculoskeletal centre. Radiological SAB microbiology culture results were compared with intra-operative surgical samples or multidisciplinary team (MDT) meeting outcome at 1-year follow-up if surgery was not undertaken. Sensitivity, specificity and accuracy of synovial aspiration (SA), synovial biopsy (SB) and simultaneous SAB were calculated. RESULTS: 103 patients (46 male, 57 female) totalling 111 procedures were analysed with mean age 65 years (range 31-83). Image-guided synovial procedures were performed on 52 (46.9%) hip and 59 (53.1%) knee joint prostheses. The mean combined sensitivity, specificity and accuracy for the entire cohort was 72.6%, 96.9% and 90%, respectively. When only SB was obtained, diagnostic accuracy (92.5%) was similar to SA alone (94.1%). In total, there were 21 (18.9%) true-positive, 80 (72.1%) true-negative, 2 (1.8%) false-positive and 8 (7.2%) false-negative cases (PPV 91.3% and NPV 90.9%). No post-procedural complications were recorded at 1-year follow-up. CONCLUSION: Percutaneous image-guided SAB is a valuable technique in assessing suspected PJI, with most samples indicative of infective status and causative organisms when validated against intra-operative results and specialist MDT evaluation. Image-guided SB is a safe and useful additional procedure following failed SA with equivalent levels of diagnostic accuracy.

The value of re-staging chest CT at first local recurrence of extremity and trunk soft tissue sarcoma.

OBJECTIVE: To determine the prevalence of pulmonary metastases on re-staging chest CT at the time of first local recurrence (LR) of trunk or extremity soft tissue sarcoma (STS). MATERIALS AND METHODS: Retrospective review of all patients diagnosed with recurrent STS between May 2007 and April 2018. Data collected included patient age and sex, site of primary STS, time to LR, recurrence site, initial tumour grade, recurrent tumour grade, findings of initial staging chest CT, and prevalence of pulmonary metastases on re-staging chest CT. RESULTS: The study included 109 patients (males = 68, females = 41; mean age 56 years, range 9-92 years). The commonest tumour sub-types were myxofibrosarcoma (27.5%), undifferentiated pleomorphic/spindle cell sarcoma (20.2%), synovial sarcoma (10.1%), and malignant peripheral nerve sheath tumour (10.1%). Initial staging chest CT demonstrated pulmonary metastases in 1 of 77 (1.3%) patients for whom CT was available for review. The mean time to LR was 30.8 months (range 3-224 months). Pulmonary metastases were diagnosed on re-staging chest CT in 26 of 109 cases (23.9%), being commonest with grade 3 STS (36.1%). Pleomorphic sarcoma (85.7%) and undifferentiated spindle cell sarcoma (33.3%) were the 2 commonest tumour sub-types associated with pulmonary metastases at first LR. CONCLUSION: Re-staging chest CT at the time of first LR of STS identified a prevalence of 23.9% pulmonary metastases, which supports the need for chest CT at the time of LR in line with the UK guidelines for the management of bone and soft tissue sarcoma. KEY POINTS: • Pulmonary metastases were diagnosed in 1.3% of soft tissue sarcomas at presentation. • Pulmonary metastases were identified in ~ 24% of patients at first local recurrence of soft tissue sarcoma, most commonly with pleomorphic sarcoma and Trojani grade tumours. • No patient with a low-grade recurrence had pulmonary metastases.

Accessory flexor carpi ulnaris: case report and review of the literature.

Most of the accessory muscles of the forearm described in the radiology literature are located either in the radial aspect of the forearm or towards the hypothenar eminence. We present an unusual case of an ulnar-sided distal forearm accessory flexor carpi ulnaris muscle presenting as a "pseudotumour" demonstrated with both ultrasound and MRI, rarely reported in the current surgical and anatomical literature. Given the location and relation to the ulnar nerve towards Guyon's canal, the accessory muscle may also predispose to distal ulnar nerve entrapment.

Technetium-99m Methylene Diphosphonate Single-photon Emission Computed Tomography/Computed Tomography of the Foot and Ankle.

The complex anatomy and function of the foot and ankle can make it difficult to determine the cause of symptoms in patients with foot and ankle pathology. Following initial clinical and radiographic assessment, additional imaging with magnetic resonance imaging may be required, which is often seen as the modality of choice. Although sensitive to pathological changes in bone metabolism and vascularity, technetium-99m (Tc-99m) bone scintigraphy often lacks the specificity and resolution required to evaluate the structures of the foot and ankle. Tc-99m methylene diphosphonate single-photon emission computed tomography/computed tomography (SPECT/CT) combines this sensitivity with the superior anatomical detail of CT, enabling better localization of pathological uptake and evaluation of associated structural changes. As a result, SPECT/CT has been growing in popularity for the assessment of patients with foot and ankle pathology where it can provide additional information that may change the initial diagnosis and subsequent management plan. Studies have reported modification of the surgical approach and site of intra-articular local anesthetic injections following SPECT/CT with good results. Interpretation of SPECT/CT studies requires an understanding of the pathological changes that result in increased tracer accumulation in addition to the CT changes that may be seen. This review aims to highlight the advantages of SPECT/CT, potential applications and explain the imaging appearances of common pathologies that may be observed.

The umbilicus: a reliable surface landmark for the aortic bifurcation?

PURPOSE: Anatomical surface landmarks are frequently used by clinicians to guide both diagnosis and treatment. Few studies have examined the reliability of vascular anatomical landmarks in living subjects. The umbilicus has traditionally been described as a surface landmark for the bifurcation of the abdominal aorta. This study examined the factors affecting the position of the umbilicus relative to that of the aortic bifurcation in 95 patients. METHODS: 106 consecutive abdominal CT scans were analysed by a surgeon and radiologist. Following exclusion of CT scans with relevant significant intra-abdominal pathology, 95 patients were included in the study. Measurements were taken of the craniocaudal distance between the aortic bifurcation and umbilicus, as well as maximum subcutaneous fat thickness at the level of the umbilicus. Patient age and gender were also documented. RESULTS: The umbilicus was found to lie -6.3 ± 26.5 mm from the aortic bifurcation. Increasing subcutaneous fat thickness was associated with a more caudal position of the umbilicus relative to the aortic bifurcation. This result was highly statistically significant in males over 65 years old. CONCLUSIONS: This study suggests that the umbilicus is a reliable clinical surface landmark for the bifurcation of the abdominal aorta. Whilst some variation in craniocaudal distance exists between patients, in the majority of cases, the bifurcation of the abdominal aorta lies within a clinically narrow range of distances from the umbilicus.

MRI appearances of the anterior fibulocalcaneus muscle: a rare anterior compartment muscle.

MRI of a 62-year-old female presenting with ankle pain demonstrated an accessory muscle within the anterior compartment of the lower leg. The muscle originated from the fibula and anterior crural septum. The tendon passed anterior to the lateral malleolus and inserted at the critical angle of Gissane on the calcaneus. This muscle was initially described in the anatomic literature by Lambert and Atsas in 2010. To our knowledge, this is the first time the MRI appearances of this muscle has been described in the radiological literature. Awareness of the fibulocalcaneal muscle is important as it may represent a cause of ankle pain. In addition, the tendon could potentially be harvested for use in reconstructive procedures.