Monica Khanna

A CT scan protocol for the detection of radiographic loosening of the glenoid component after total shoulder arthroplasty

Background and purpose It is difficult to evaluate glenoid component periprosthetic radiolucencies in total shoulder arthroplasties (TSAs) using plain radiographs. This study was performed to evaluate whether computed tomography (CT) using a specific patient position in the CT scanner provides a better method for assessing radiolucencies in TSA. Methods Following TSA, 11 patients were CT scanned in a lateral decubitus position with maximum forward flexion, which aligns the glenoid orientation with the axis of the CT scanner. Follow-up CT scanning is part of our routine patient care. Glenoid component periprosthetic lucency was assessed according to the Molé score and it was compared to routine plain radiographs by 5 observers. Results The protocol almost completely eliminated metal artifacts in the CT images and allowed accurate assessment of periprosthetic lucency of the glenoid fixation. Positioning of the patient within the CT scanner as described was possible for all 11 patients. A radiolucent line was identified in 54 of the 55 observed CT scans and osteolysis was identified in 25 observations. The average radiolucent line Molé score was 3.4 (SD 2.7) points with plain radiographs and 9.5 (SD 0.8) points with CT scans (p = 0.001). The mean intra-observer variance was lower in the CT scan group than in the plain radiograph group (p = 0.001). Interpretation The CT scan protocol we used is of clinical value in routine assessment of glenoid periprosthetic lucency after TSA. The technique improves the ability to detect and monitor radiolucent lines and, therefore, possibly implant loosening also.

Massive localised lymphoedema: clinical presentation and MR imaging characteristics

Three morbidly obese women were referred to us with suspected soft-tissue sarcomas. All lesions arose from the medial subcutaneous tissues of the thigh, and were shown to represent massive localised lymphoedema (MLL), a rare condition occurring in morbidly obese adults. MR imaging typically demonstrates a sharply demarcated, pedunculated mass consisting of fat partitioned by fibrous septae surrounded by a thickened dermis. There is oedema both within the mass and tracking along the subcutaneous septae in a “lace-like” fashion outwards from the pedicle, outlining large lobules of fat. Minimal enhancement is observed within the dermis of the lesion following intravenous gadolinium administration. Obesity is a growing problem that is likely to result in an increase in the prevalence of this condition; therefore, familiarity with the radiological appearance is important in establishing a correct diagnosis in this condition that may mimic a soft-tissue sarcoma.

Physes around the shoulder girdle: normal development and injury patterns.

Traumatic injuries involving the scapula and clavicle in skeletally immature patients have unique characteristics that distinguish them from similar injuries in the mature skeleton. Fractures involving unossified cartilage and unfused epiphyses are difficult to appreciate on plain radiographs and computed tomography (CT) imaging. Knowledge of the developmental anatomy and normal radiological appearances during different stages of development of these bones is an essential prerequisite for the radiologist tasked with interpreting the imaging of such injuries in order to avoid potential diagnostic pitfalls. With increased availability and improved resolution of magnetic resonance imaging (MRI), we are now better able to distinguish between true joint dislocations and epiphyseal injuries. Making this distinction is important because it can have implications with regards to how the patient is managed and the prognosis.

Image-Guided Intervention of the Postoperative Foot and Ankle After Ligament and Tendon Repair

This review article describes the potential range of image-guided interventional procedures performed following foot and ankle ligament and/or tendon repair. Diagnosis of the cause of recurrent or persistent pain/symptoms in this postoperative group is challenging and requires a coordinated clinical and radiologic assessment. This directs appropriate treatment including image-guided intervention that may be used both as a diagnostic tool and a therapeutic option. There is a paucity of high-quality studies on the role of image-guided intervention in the foot and ankle after ligament/tendon repair. Many of the procedures used in this group are extrapolated from other areas of the body or the preoperative scenario. We review the role of imaging to identify the cause of postsurgical symptoms and to direct appropriate image-guided intervention. The available injectables and their roles are discussed. Specific surgical procedures are described including lateral ligament repair, Achilles repair, posterior tibialis tendon surgery, and peroneal tendon surgery.

A painful swollen thigh in a diabetic patient: diabetic myonecrosis

A 40-year-old woman presented to the emergency department in August, 2013, with a 6 week history of gradual onset pain and swelling over the anteromedial aspect of her left thigh. She had a 10 year history of type II diabetes and was taking oral hypoglycaemic agents, had no history of trauma, and no constitutional symptoms. Physical examination revealed pronounced generalised swelling of the left thigh. The overlying skin was hot and the underlying soft tissue was tender to palpation, with no fl uctuance, erythema or rash. She was unable to weight bear or straight leg raise. Sensation and pulses were intact throughout. She had no diabetic macrovascular complications, but did have bilateral nonproliferative retinopathy. Blood tests showed C-reactive protein 38·1 mg/L (normal: 0–5 mg/L) and erythrocyte sedimentation rate of 95 mm/h (normal: 0–12 mm/h). Glycosylated haemoglobin was 149 mmol/mol (normal: 20–42 mmol/mol). Urine protein/creatinine ratio was 28 units (reference range 0–25). Autoantibody screen, creatinine kinase, and all other blood tests remained normal throughout admission. Doppler ultrasound of the left thigh revealed subcutaneous oedema, but no evidence of deep vein thrombosis or discrete collection. MRI showed extensive soft tissue oedema and diff use swelling of the vastus medialis and intermedius in the left distal thigh. Both muscles heterogeneously enhanced after contrast administration, suggesting necrosis (fi gure). Ultrasound-guided biopsy of the left vastus medialis and lateralis showed widespread fi bre necrosis with endomysial oedema and mild, focal chronic infl ammation (fi gure). Features were consistent with diabetic myonecrosis, also known as diabetic muscle infarction. The patient was treated conservatively with bed rest, non-steroidal anti-infl ammatory medication (naproxen), and physiotherapy. She was started on insulin to improve her glycaemic control. She recovered well and was discharged after 4 weeks. At follow-up in October, 2013, the pain and swelling had improved signifi cantly, and her glycaemic control was better. A systematic review showed that diabetic muscle infarction was more common in women (61·5%), with a mean age at presentation of 42·6 years. Almost 60% of cases had type I diabetes, and the mean duration of disease was 14·3 years. The cause is not fully understood. Several hypotheses have been proposed, including atherosclerosis, hypoxia-reperfusion injury, vasculitis, thrombosis, and a hyper coagulable state. The short-term outlook is generally good, with spontaneous resolution over weeks to months. However, long-term prognosis is poor, and recurrence has been reported in up to 48% of patients, in most cases aff ecting other muscle groups. This case emphasises the need for a high index of suspicion of diabetic muscle infarction when a patient with poorly controlled diabetes presents with nontraumatic limb pain. Clinical history, MRI features, and histology are important to confi rm the correct diagnosis. Muscle biopsy is especially important, to exclude other causes such as pyomyositis, necrotising fasciitis, and neoplasm.

An unusual complication of tocilizumab therapy: MRI appearances of thenar eminence pyomyositis.

Joint Bone Spine - In Press.Proof corrected by the author Available online since mardi 11 decembre 2012

Salter-Harris Type 1 coracoid process fracture in a rugby playing adolescent

Fractures of the coracoid process are uncommon and when they do occur, are often mistaken for injuries to the acromi oclavicular joint. We report a case of a 15-year-old boy who sustained a Salter-Harris Type 1 fracture through his coracoid process alongside strain of the acromioclavicular and coracoclavicular ligaments. Additional imaging, specifically MRI, was critical in both correctly identifying this injury as a coracoid process fracture and also in determining that conservative management was the best course of action. Optimum management of such injuries remains controversial, specifically with regards to skeletally immature patients. In our case, the injury was identified clearly on MRI and managed conservatively, with the patient making a full recovery and a return to contact rugby after 3 months.

Femoral fracture type can be predicted from femoral structure: A finite element study validated by digital volume correlation experiments

Proximal femoral fractures can be categorized into two main types: Neck and intertrochanteric fractures accounting for 53% and 43% of all proximal femoral fractures, respectively. The possibility to predict the type of fracture a specific patient is predisposed to would allow drug and exercise therapies, hip protector design, and prophylactic surgery to be better targeted for this patient rendering fracture preventing strategies more effective. This study hypothesized that the type of fracture is closely related to the patient‐specific femoral structure and predictable by finite element (FE) methods. Fourteen femora were DXA scanned, CT scanned, and mechanically tested to fracture. FE‐predicted fracture patterns were compared to experimentally observed fracture patterns. Measurements of strain patterns to explain neck and intertrochanteric fracture patterns were performed using a digital volume correlation (DVC) technique and compared to FE‐predicted strains and experimentally observed fracture patterns. Although loaded identically, the femora exhibited different fracture types (six neck and eight intertrochanteric fractures). CT‐based FE models matched the experimental observations well (86%) demonstrating that the fracture type can be predicted. DVC‐measured and FE‐predicted strains showed obvious consistency. Neither DXA‐based BMD nor any morphologic characteristics such as neck diameter, femoral neck length, or neck shaft angle were associated with fracture type. In conclusion, patient‐specific femoral structure correlates with fracture type and FE analyses were able to predict these fracture types. Also, the demonstration of FE and DVC as metrics of the strains in bones may be of substantial clinical value, informing treatment strategies and device selection and design.

Part II - Dorsal wrist pain and swelling post trauma 2

DiagnosisTraumatic lipohaematoma of the extensor tendon sheaths(compartments 2–4) post distal radial fracture.DiscussionIn the same way that identification of a lipohaemarthrosisalerts the reading radiologist to the presence of an intra-articular fracture, the visualisation of a lipohaematoma ofthe tendon sheath after trauma may herald the presence offracture extending into an osseous groove for a tendon. Italso indicates injury to the tendon sheath, and raises thepossibility of associated tendon injury, which may warrantfurther assessment of the affected tendon with magneticresonance imaging.A 29-year-old man presented post cyclist vs car accident.CTshowed a comminuted distal radial fracture. As shown inFig. 3 of the case presentation, a fracture line cleavedcompletely through the base of Lister’s tubercle (largerarrow) with disruption of the floor of the fourth compart-ment by an acute angled sharp fracture fragment (smallerarrow). Fracture lines extended into the grooves for extensorpollicis longus (3rd extensor compartment) and extensordigitorum (4th extensor compartment). A separate fracturepassed into the grooves for extensor carpi radialis longusand brevis (2nd extensor compartment). The edges of thefracture fragments were sharply angulated and disrupted theosseous grooves for the 3rd and 4th compartment tendons.The medullary cavity of the distal radius appeared open tothe tendon sheaths of both the 3rd and 4th extensor compart-ments. An oblique sagittal fracture line was also seenextending from the volar surface of the radius through thearticular surface. A small lipohaemarthrosis of the radio-carpal joint was present. Further distally, within the tendonsheaths of the second, third and fourth extensor compart-ments prominent fat–fluid levels within the tendon sheathswere seen, accounting for the gross soft tissue swelling seenon the radiograph. The lipohaematoma was most volumi-nous within the distal third and fourth compartment sheaths,and comparatively small in the second compartmentsheaths. The average Hounsfield Unit density of the upper(and, by volume, larger) layer within the tendon sheaths wasapproximately −90, consistent with the presence of fat.Magnetic resonance imaging obtained 4 days after theinjury showed fat-fluid layers within the non-dependentaspect of the sheaths of the second, third and fourth com-partments. A layer of high T1 signal within the non-dependent aspect of the sheaths (part 1 figure 2 - arrow),which completely saturated on T2 fat suppression and cor-responded to the position of the −90 HU density materialseen on the CT, was present, confirming the presence of fat.The distal radial fracture is also evident on this image. Therewas focal irregular high T2 signal seen along the deep radialside surface of tendons of the extensor digitorum and exten-sor pollicis longus adjacent to the sharp fracture edges,consistent with tendon abrasion, but no frank split or rupturewas seen. The dependent portion of the lipohaematomashowed signal characteristics consistent with a mixture offluid and blood. Figure 4 of this article shows a fracture lineevident in the distal radius, which appears to have disruptedthe tendon sheath and is opening into the floor of the fourth

Dorsal wrist pain and swelling post trauma

A 29-year-old male presented immediately following a cyclist versus car accident with right wrist pain and swelling. The swelling was prominent, and located primarily over the dorsal aspect of the wrist and hand. A CT image from a study at the time of presentation is shown in Fig. 1, and a sagittal T1-weighted MRI 4 days after injury in Fig. 2. What is the cause of the swelling at the dorsal aspect of the wrist and hand?