What is the natural history of asymptomatic pseudotumours in metal-on-metal hip resurfacing patients?

PURPOSE: We assessed the natural history of asymptomatic pseudotumours associated with metal-on-metal hip resurfacings (MoMHRs), and factors associated with future revision. METHODS: In 2007-2008, we identified 25 MoMHRs (21 patients; mean age 59.9 years; 76% female) with asymptomatic pseudotumours. All patients underwent identical initial assessment (ultrasound, blood metal ions, radiographs, Oxford Hip Score [OHS]) and were considered asymptomatic because they denied experiencing hip symptoms, were satisfied with their MoMHR surgery, and had good or excellent OHSs (≥34). In 2012-2013, repeat assessments were performed in all non-revised patients. RESULTS: Revision for pseudotumour was performed/recommended in 15 MoMHRs (60%) at a mean 2.7 years (range 0.4-6.4 years) from initial assessment, with 14 developing symptoms before revision. Non-revised MoMHRs (n = 10) underwent repeat ultrasound at a mean 5.1 years (range 4.0-6.5 years) later, with no changes in pseudotumour volume (p = 0.956) or OHS (p = 0.065) between assessments. High blood cobalt (p = 0.0048) and chromium (p = 0.0162), large pseudotumours (p = 0.0458), low OHS (p = 0.0183), and bilateral MoMHRs (p = 0.049) predicted future revision. Patients with blood metal ions above established unilateral/bilateral thresholds and/or initial pseudotumours >30 cm3 had an 86.7% sensitivity, 70.0% specificity, 81.2% positive predictive value, and 77.8% negative predictive value for future revision. CONCLUSIONS: MoMHR patients with initially asymptomatic pseudotumours often become symptomatic and require revision. Patients with high blood metal ions and/or pseudotumours >30 cm3 should remain under annual surveillance or be considered for revision (especially in patients also having lower initial OHSs, bilateral MoMHRs, and/or those becoming symptomatic). Less regular surveillance of patients outside these parameters appears acceptable.

How Should We Follow-Up Asymptomatic Metal-on-Metal Hip Resurfacing Patients? A Prospective Longitudinal Cohort Study.

Current surveillance for metal-on-metal hip resurfacing (MoMHR) patients is not evidence based. This study established changes that occurred in 152 asymptomatic MoMHRs using repeat ultrasound and patient-reported outcomes. Factors associated with (1) ultrasound progression and (2) developing new pseudotumors were analyzed. Patients underwent repeat assessments 4.3 years later. Ultrasound progression was observed in 19% (n = 29), with 10% (n = 15) developing new pseudotumors. Key predictors of ultrasound progression included high blood cobalt (P = .00013) and chromium (P = .00065), and high initial ultrasound grade (P = .003) and volume (P = .036). No asymptomatic MoMHRs with initially normal metal ions (<2 µg/L) and normal ultrasounds (33% of cohort) developed new pseudotumors. This patient subgroup does not require repeat follow-up within 5 years.

Arthritis at the shoulder joint.

The shoulder is a complex joint with numerous structures contributing to mobility and stability. Shoulder pain is a common clinical complaint that may be due to a wide spectrum of disorders including rotator cuff disease, instability, and arthropathy. Primary osteoarthritis of the shoulder joint is uncommon because it is a non-weight-bearing joint. Significant osteoarthritis of the glenohumeral joint is unusual in the absence of trauma, and the detection of advanced degenerative changes in patients without a known history of trauma should alert the clinician to search for other disorders. This article reviews the pathogenesis, clinical manifestations, and key imaging findings of the common categories of the arthritis affecting the glenohumeral joint.

Ischiofemoral impingement: a retrospective analysis of cases in a specialist orthopaedic centre over a four-year period.

BACKGROUND: Ischiofemoral impingement is a recently identified cause of chronic hip pain, the pathophysiology and clinical features of which are poorly understood.
 AIM: To determine the clinical significance of MRI findings of ischiofemoral impingement.
 MATERIALS AND METHODS: Retrospective search for cases of ischiofemoral impingement in the Nuffield Orthopaedic Centre, Oxford, over a 4 year period, and review of medical notes to identify correlation between clinical and MRI features.
 RESULTS: Sixteen hips in 13 patients with MRI signs of ischiofemoral impingement were identified. All patients were females with a median age of 36 years (range 17-80 years). In six patients the symptoms corresponded to the side of the quadratus femoris abnormality and narrowed ischiofemoral distance. In two patients the symptoms were on the same side as the abnormality but were more consistent with back pain and sciatica. In five patients the symptoms were not anatomically related to the abnormality. Abnormalities identified; seven patients had muscle oedema (six unilateral, one bilateral) and six had muscle wasting (four unilateral, two bilateral). Of the patients with quadratus femoris oedema, two had gluteus medius enthesopathy and one had hamstring enthesopathy. Two patients presented with a chronic loud clunking of the hip on walking.
 CONCLUSIONS: Ischiofemoral impingement on MRI is seen in patients with pain localised to the ipsilateral buttock and in patients with symptoms unrelated to the abnormality. The condition may be associated with wasting or oedema of the quadratus femoris muscle on MRI and may occur secondary to injury in other muscles controlling movement of the hip such as the hamstrings and gluteus medius. Ischiofemoral impingement is a cause of a clunking hip.

The extensor mechanism of the knee.

Disorders related to the knee extensor mechanism are common and rarely require imaging. Non specific anterior knee pain, fracture, dislocation, overuse tendinopathy and chronic patellofemoral instability are the commonest conditions encountered. Imaging is used in acute trauma, and for the assessment of cases of anterior knee pain resistant to conservative measures. The role of the radiograph is now largely restricted to cases of suspected fracture. Ultrasound is the optimum technique for suspected tendon and bursal pathology and MRI is widely used for the assessment of dysplasia and instability of the patellofemoral joint, including acute dislocation.

Localized Ewing sarcoma of the tibia.

Ewing sarcoma (ES) is a high-grade malignant primary round cell tumour of bone in which there is commonly extension into extraosseous soft tissues at the time of diagnosis. This report details the clinical, radiological and pathological features of a case of ES of the tibia in which there was extensive osseous involvement but no infiltration beyond the periosteum into surrounding soft tissue. We also record the findings of one other ES case that exhibited similar behaviour. Both cases were male, involved the tibia and had the characteristic t (11;22) (q24;q12) translocation. No recurrence of tumour or metastasis has been seen in these two cases, both of which have had 6 years follow-up. Our findings indicate that there is heterogeneity in the behaviour of ES and show that localized ES is associated with a good prognosis.

Clinical indications for musculoskeletal ultrasound: a Delphi-based consensus paper of the European Society of Musculoskeletal Radiology.

OBJECTIVE: To develop clinical guidelines for musculoskeletal ultrasound (MSKUS) referral in Europe. METHODS: Sixteen musculoskeletal radiologists from seven European countries participated in a consensus-based interactive process (Delphi method) using consecutive questionnaires and consensus procedure meetings at several European radiology meetings. The evaluation of musculoskeletal diseases was established by literature reviews, followed by consensus on clinical utility in three consensus meetings. This involved a thorough, transparent, iterative approach which including interview, questionnaire, Delphi and standard setting methodologies. European MSK radiologists with a special interest in MSKUS formed two different expert groups who worked on reaching a consensus in the first two meetings. The third meeting resolved questions that did not achieve a consensus level of 67% using the first two questionnaires. RESULTS: On expert consensus, the use of MSKUS is indicated to detect joint synovitis, fluid and septic effusion for potential aspiration, and poorly indicated to detect loose bodies. Recommendations for most appropriate use of musculoskeletal ultrasound are reported in six areas relevant to musculoskeletal ultrasound: hand/wrist, elbow, shoulder, hip, knee and ankle/foot. CONCLUSION: A comprehensive evidence-based, expert consensus-defined educational framework on clinical ultrsound is presented. This should facilitate referrals for this important imaging technique throughout Europe. KEY POINTS: Musculoskeletal ultrasound is indicated for detecting joint synovitis, effusions and fluid collections. • Musculoskeletal ultrasound is poor at detecting loose bodies. • Musculoskeletal ultrasound is relevant for most joints.

A MRI classification of periprosthetic soft tissue masses (pseudotumours) associated with metal-on-metal resurfacing hip arthroplasty.

OBJECTIVE: Metal-on-metal hip resurfacing arthroplasty (MoMHRA) has become a popular option for young patients requiring hip replacement. A recognised complication is the formation of a symptomatic reactive periprosthetic soft tissue mass (pseudotumour). We present a radiological classification system for these reactive masses, dividing them into three groups: Type I are thin-walled cystic masses (cyst wall <3 mm), Type II are thick-walled cystic masses (cyst wall >3 mm, but less than the diameter of the cystic component) and Type III are predominantly solid masses. MATERIALS AND METHODS: We reviewed all MRI performed over a 4-year period in patients with primary MoMHRA referred to our institution. In all cases the masses were assessed on MRI according to size, anatomical position, signal intensity and involvement of bone, muscle or neighbouring neurovascular bundles. RESULTS: Periprosthetic masses were seen in 33 hips in 17 female (7 bilateral) and 8 male patients (1 bilateral). The Type I lesions were the most common and more likely to be posterior to the hip joint. The Type III masses were significantly larger than the cystic lesions and were more likely to be located anterior to the hip joint. To date 22 patients have undergone revision surgery with conversions to total hip replacement. Severity of symptoms and revision rates were lowest in the Type I group and highest in the Type III group. CONCLUSION: Solid anterior pseudotumours were most likely to have the more severe symptoms and require revision surgery.

How to image metal-on-metal prostheses and their complications.

OBJECTIVE: Metal-on-metal arthroplasty is a durable alternative to traditional metal-on-polyethylene total hip replacement for young active patients. Although midterm results for resurfacing arthroplasty are reasonable, there is increasing recognition of the problem of metal-induced periprosthetic reactive masses. CONCLUSION: Imaging plays an important role in the investigation of symptomatic metal-on-metal arthroplasty. Radiographs will identify fracture and loosening, but cross-sectional imaging is required to diagnose and stage periprosthetic reactive masses.

Hip resurfacing and pseudotumour.

Metal on metal hip resurfacing has been used widely over the last ten years but there has been recent concern about destructive soft tissue reactions, which have been called pseudotumours by some authors. This has generated considerable controversy. This review explains why pseudotumours occur after resurfacing and how they can be prevented. It also supports the continued use of resurfacing in appropriate patients by appropriately trained surgeons.

Persistent ankle pain following a sprain: a review of imaging.

The initial diagnosis of an "ankle sprain" is not always correct. Prolonged pain, swelling and disability sufficient to limit the activity and refractory to treatment following an ankle injury are not typical of an ankle sprain and should alert the clinician of the possibility of an alternative or an associated diagnosis. There are several conditions that can be misdiagnosed as an ankle sprain and those include ankle syndesmosis injuries, sinus tarsi syndrome, ankle and hind foot fractures, osteochondral lesions, posterior tibialis and peroneal tendons abnormalities, spring ligament damage, impingement syndromes and reflex sympathetic dystrophy. In this review, we discuss the imaging features of these conditions that can clinically mimic an ankle sprain. It is crucial to remember that unresolved ankle pain following an injury is not always just due to a "sprain".

Immunophenotypic analysis of glomus coccygeum associated with coccygodynia.

OBJECTIVE: Glomus coccygeum is a glomus body which is found in the pericoccygeal soft tissue. This specialised arteriovenous anastomosis is a non-pathological vestigial structure usually larger than its equivalent in the distal extremities. Its prevalence is uncertain. Glomus coccygeum has been associated with coccygodynia and can cause diagnostic problems to pathologists unfamiliar with this entity. MATERIALS AND METHODS: The presence of a glomus coccygeum was sought in 40 coccygectomy specimens and correlated with clinical, radiological and histological findings. RESULTS: A glomus coccygeum was identified in 13 samples (35%). Glomus cells expressed smooth muscle actin (SMA) and were negative for desmin, S100, cytokeratin and a wide range of vascular markers. Proliferative activity was low. Pre-operative MRI did not identify these tiny lesions, and most patients with coccygodynia did not have a glomus coccygeum. CONCLUSION: Glomus coccygeum is a common microanatomical structure which can be distinguished from glomus and other tumours by its small size, SMA expression and low proliferative activity.

Efficacy of ultrasound-guided steroid injections for pain management of midfoot joint degenerative disease.

OBJECTIVE: To examine the efficacy of ultrasound (US)-guided injections for midfoot joint degenerative changes. MATERIALS AND METHODS: The US images and radiographs of 63 patients with midfoot joint degenerative changes were retrospectively reviewed. In those patients who had US-guided intra-articular steroid injection, the response to the injection was recorded by reviewing the 2-week pain diaries and clinical notes. Partial or complete pain relief was defined as a positive response and the same or increased level of pain as a negative response to the injection. RESULTS: Fifty-nine (59/63, 93.6%) patients with midfoot joint degenerative changes received US-guided injection. The majority of patients had a positive response up to 3 months post-injection (78.4% still experiencing pain relief at 2 weeks, 57.5% at 3 months and fewer than 15% of patients further than 3 months post-injection). The number of positive therapeutic responses did not differ significantly between patients with diagnostic and non-diagnostic response (p = 0.2636). CONCLUSIONS: US-guided intra-articular injections for midfoot degenerative changes can have a good therapeutic result in the majority of patients up to 3 months post-injection. Therapeutic response cannot be predicted by a positive diagnostic response.

Case report: imaging and surgical treatment of a snapping hip due to ischiofemoral impingement.

An association between hip pain and quadratus femoris MRI abnormality with concurrent narrowing of the ischiofemoral space has been reported in a number of patients to date, raising the possibility that the muscular damage observed is due to ischiofemoral impingement. Possible impingement has been noted primarily in middle-aged females either with or without a history of trauma or surgery, and associated snapping of the hip is a rarely described feature. We report here on a 17-year-old girl who presented with post-traumatic hip pain; she later developed evidence of ischiofemoral narrowing and quadratus femoris edema on MRI in addition to an audible snapping. Surgical resection of the lesser trochanter was performed, relieving both her hip pain and the snapping. To our knowledge, this is the first reported case of non-iatrogenic ischiofemoral impingement with surgical confirmation. The diagnosis of ischiofemoral impingement should be considered in patients complaining of a snapping hip.

Metal-on-metal hip resurfacings--a radiological perspective.

It is important to be aware of the various complications related to resurfacing arthroplasty of the hip (RSA) and the spectrum of findings that may be encountered on imaging. The bone conserving metal-on-metal (MOM) hip resurfacing has become increasingly popular over the last ten years, especially in young and active patients. Initial reports have been encouraging, but long-term outcome is still unknown. Early post operative complications are rare and have been well documented in the literature. Medium and long term complications are less well understood. A rare but important problem seen at this stage is the appearance of a cystic or solid periarticular reactive mass, which occurs predominately in women and usually affects both hips when seen in patients with bilateral RSAs. The following imaging findings are illustrated and their significance discussed; Uncomplicated hip resurfacing arthroplasty, radiolucency around the femoral peg, femoral neck fracture, loosening and infection, suboptimal component position, femoral notching, dislocation, heterotopic ossification, femoral neck thinning and reactive masses. The radiologist should be aware of the normal radiographic appearances and the variety of complications that may occur following RSA and should recommend ultrasound or MRI in patients with an unexplained symptomatic hip and normal radiographs.

"Asymptomatic" pseudotumors after metal-on-metal hip resurfacing arthroplasty: prevalence and metal ion study.

Symptomatic abnormal periprosthetic soft-tissue reactions ("pseudotumors") have been reported after metal-on-metal hip resurfacing arthroplasty (MoMHRA). The aims of this study were (1) to determine the prevalence of asymptomatic pseudotumors after MoMHRA and (2) to measure metal ion levels in these patients. A total of 201 hips in 158 patients were evaluated at a mean follow-up of 61 months (range, 36-88) using ultrasound/magnetic resonance imaging and serum/hip aspirate cobalt and chromium measurements. Pseudotumors found in 7 patients (4%) were associated with significantly higher cobalt and chromium levels and inferior functional scores. Elevated levels of cobalt and chromium ions suggest that pseudotumors are associated with increased wear generated from metal-on-metal articulations. Clinicians need to be aware of pseudotumors as a differential diagnosis during clinical evaluation of MoMHRA patients, and further imaging such as ultrasound or magnetic resonance imaging is recommended to confirm the diagnosis.

Meniscal tears with displaced fragments: common patterns on magnetic resonance imaging.

OBJECTIVE: To identify the commonly occurring patterns of small displaced tears of the menisci of the knee on magnetic resonance imaging (MRI). MATERIALS AND METHODS: A retrospective review of knee MRI scans over 16 months at two hospitals provided 70 studies with 73 displaced meniscal fragments for analysis. Fragment position was recorded. RESULTS: Two common positions were identified for medial fragments. For the medial meniscus, 93% of fragments were positioned medially or posterolaterally. The medially displaced fragments were positioned in either the superior or inferior recesses. Lateral meniscal fragments were more evenly dispersed. CONCLUSION: The pattern of small displaced tears of the medial meniscus is highly predictable. Awareness of the typical locations of these fragments should aid the reporter in identifying these lesions on MRI.

Morton's neuroma: diagnostic accuracy, effect on treatment time and costs of direct referral to ultrasound by primary care physicians.

BACKGROUND: The first-line treatment for symptomatic Morton's neuroma in our hospital is a perineural ultrasound-guided injection of corticosteroid and local anaesthetic (USI). The NHS has recently implemented 18-week referral-to-treatment targets. When GPs specifically suggest a diagnosis of Morton's neuroma there are two referral pathways in our hospital: direct referral to radiology for USI (limited slots) or referral to the specialist foot and ankle clinic. Patients with less specific referral letters are also evaluated in clinic and referred for USI as appropriate. METHODS: A retrospective audit was performed reviewing referral letters from general practitioners (GPs) in 2005-2006. A comparison was made between the referral pathways for time-to-treatment (TTT), accuracy of GP diagnosis, and cost implications. RESULTS: In the directly referred group, the median TTT was 99 days, compared to 206 days for patients who went via a foot and ankle clinic (P < 0.001). Of 57 patients with a GP diagnosis of Morton's neuroma, 40 (70%) had the diagnosis confirmed on USI compared to 44 of 64 (69%) patients referred by a foot and ankle surgeon, showing no significant difference between the groups (P = 0.87). CONCLUSION: For patients with features highly suggestive of a Morton's neuroma, direct referral from primary care for USI had a similar accuracy to referral from a specialist hospital clinic and the time-to-treatment was significantly shorter. The mean waiting time of this group was within the 18-week government target without any changes to our current radiology protocols.