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Lateral ankle pain is a common clinical presentation having several important causes, including lateral ligament injury, peroneal tendon injury, sinus tarsi syndrome, and nerve entrapments. However, other causes should be kept in mind in patients with unusual patterns of pain or intractable symptoms. We present a review of common and some unusual causes of lateral ankle pain including a review of post-operative imaging findings following surgery for lateral ankle ligament and peroneal tendon injuries.

The aim of this article was to review the current status of ultrasound imaging of patients with rheumatological disorders of the hands and feet. Ultrasound machines with high-resolution surface probes are readily available in most radiology departments and can be used to address important clinical questions posed by the rheumatologist and sports and rehabilitation physician. There is increasing evidence that ultrasound detects synovitis that is silent to clinical examination. Detection and classification of synovitis and the early detection of bone erosions are important in clinical decision making. Ultrasound has many advantages over other imaging techniques with which it is compared, particularly magnetic resonance. The ability to carry out a rapid assessment of many widely spaced joints, coupled with clinical correlation, the ability to move and stress musculoskeletal structures and the use of ultrasound to guide therapy accurately are principal amongst these. The use of colour flow Doppler studies provides a measure of neovascularisation within the synovial lining of joints and tendons, and within tendons themselves, that is not available with other imaging techniques. Disadvantages compared to MRI include small field of view, poor image presentation, and difficulty in demonstrating cartilage and deep joints in their entirety. Contrast-enhanced magnetic resonance provides a better measure of capillary permeability and extracellular fluid than does ultrasound. The ability to image simultaneously multiple small joints in the hands and feet and their enhancement characteristics cannot be matched with ultrasound, though future developments in 3-D ultrasound may narrow this gap. Magnetic resonance provides a more uniform and reproducible image for long-term follow-up studies.

Clinical assessment of the patient with shoulder symptoms can usually localize the cause to one of a few syndromes, each associated with specific imaging questions. MRI is used as the primary form of investigation for recurrent dislocation, SLAP lesions and PSI, as well as articular cartilage, synovial disease, tumours and infection. Ultrasound plays the leading role in impingement, acromioclavicular disease, dynamic assessment and guided therapy. Both techniques are reported to play a role in adhesive capsulitis. In our hospital, approximately four times as many shoulder ultrasound examinations as shoulder MRI are carried out, but elsewhere these proportions will vary according to the prevalence of clinical syndromes in the population being treated.

Objective: To determine the patterns of patellar motion in subjects without knee symptoms using dynamic magnetic resonance imaging (MRI)., Design: Patellar tracking MR examinations were performed on 50 asymptomatic volunteers. The presence and degree of lateral subluxation and tilt of the patella was assessed independently by three radiologists, and discrepancies resolved by consensus. Using the same criteria, the tracking pattern in 50 consecutive patients, recently referred for imaging assessment of anterior knee pain, was studied., Patients: Fifty volunteers (22 male, mean age 37 years) and 50 unmatched patients (15 male, mean age 25.5 years) were examined., Results and Conclusions: Forty-one per cent of a total of 97 knees in the volunteer group showed evidence of lateral subluxation, which was either minimal (grade 1, 32%) or minor (grade 2, 9%). No volunteer demonstrated major (grade 3) subluxation; lateral tilt without translation of the patella was also seen (2%). In the patient group, higher grades of lateral subluxation were more common. Minimal (grade 1) lateralization is a common movement pattern of the patella on knee extension, and should be regarded as normal.

The infrapatellar fat pad of Hoffa is commonly injured but rarely discussed in the radiological literature. Abnormalities within it most commonly are the consequences of trauma and degeneration, but inflammatory and neoplastic diseases of the synovium can be confined to the fat pad. The commonest traumatic lesions follow arthroscopy, but intrinsic signal abnormalities can also be due to posterior and superior impingements syndromes and following patellar dislocation. Infrapatellar plica syndrome may also be traumatic in aetiology. The precise aetiology of ganglion cysts is not understood; the principal differential diagnosis is a meniscal or cruciate cyst. Hoffa's fat pad contains residual synovial tissue, meaning that primary neoplastic conditions of synovium may originate and be confined to the fat pad. Inflammatory changes along the posterior border of the pad may also be used to help differentiate effusion from acute synovitis on unenhanced MR examinations.

Anterior knee pain is a common complaint in the orthopaedic clinic. The differential diagnosis is wide and the principal goal of initial assessment is to detect remediable causes. The majority of patients do not have a specific disease and increasingly interest has focused on the role of patello-femoro-tibial morphology and of patellar maltracking in the aetiology of anterior knee pain. Classification in this group of patients is poor and there is no uniform agreement on which patient groups benefit from treatment and which treatment is best. Much of the literature involves relatively small numbers of patients, is poorly controlled and there is little agreement on outcome measures. The purpose of this review is to outline the current status of the imaging assessment of recalcitrant anterior knee pain with particular reference to patellar maltracking.

We describe a case of plant-thorn synovitis of the elbow resulting from a thorn injury. This caused recurrent pain and swelling of the elbow over a 3-month period. A magnetic resonance imaging examination was initially requested to exclude septic arthritis, and demonstrated a joint effusion, synovitis, and a 2-cm linear opacity embedded in the synovium. Ultrasound was performed prior to surgery to confirm these findings and provide accurate localization of the thorn fragment, later removed at surgery. To our knowledge this is the first example of this condition that has been confirmed by radiological imaging prior to surgery.

Objective: To define the imaging appearances in three cases of posteromedial subtalar coalition., Design: Three patients who presented with hindfoot pain were found to have non-osseous coalition involving the posteromedial hindfoot. This entity is distinct from conventional middle facet coalition as the sustentaculum is uninvolved., Results: Plain radiographs, available in two cases, demonstrated subtle irregularity of the posterior facet. MRI (three cases) demonstrated a mixed bony and cartilaginous mass lying posterior to the sustentaculum. There was trabecular oedema within the mass and adjacent talus, and narrowing of the space between the middle and posterior facets. Prominence and dilatation of the posterior tibial veins with tenosynovitis of the adjacent tibialis posterior tendon was seen. CT demonstrated the bony mass but did not detect the adjacent bony oedema., Conclusion: Posteromedial subtalar coalition may present with hindfoot pain and stiffness. The presence of a pseudarthrosis posterior to a normal middle facet is characteristic. The abnormality can be difficult to detect on plain radiographs.

Anteroposterior translation of the humeral head within the glenohumeral joint was investigated using MRI. Ten normal shoulders, 11 recurrent anterior dislocations, 10 stabilised shoulders after the Putti-Platt operation and one shoulder with multidirectional instability, were scanned. The arm was positioned in internal and external rotation and in an overhead position. Gradient echo volume acquisition scans were carried out, and 22 were suitable for evaluation. Consistent results were obtained in the normal shoulders. The unstable and unstable shoulders showed higher variance, but there was no significant anterior translation in external rotation in any group. The range of external rotation was significantly reduced in the unstable and stabilised shoulders. A trend towards posterior translation was found in internal rotation with a mean of 1 (+/- 0.44) in normal, 0.89 (+/- 1.67) in unstable and 1.6 (+/- 1.4) in stabilised shoulders.