Presurgical Perspective and Postsurgical Evaluation of Morton's Neuroma and Other Nerve Lesions

Magnetic resonance imaging (MRI) is a robust method used for both preoperative and postoperative evaluation of Morton's neuroma and other neural lesions. MRI is used to confirm the diagnosis and for precise localization, estimation of outcome, and differential diagnoses. The differential diagnoses include mechanically induced plantar plate ruptures with associated Morton's neuroma-like tumors in the intermetatarsal/interdigital spaces; mechanical fibrosis cushion formations and pseudo bursae in the plantar foot adipose tissue; rheumatologic affections, such as rheumatoid nodules, gouty nodules, and intermetatarsal bursitis; and lastly the tenosynovial giant cell tumor (formerly called pigmented villonodular synovitis). In the postoperative evaluation after resection of Morton's neuroma, the same differential diagnoses must be considered as in the preoperative evaluation. Similarly, a high prevalence (up to 25%) of asymptomatic Morton's neuroma-like findings in the intermetatarsal and interdigital spaces should be kept in mind when interpreting postoperative recurrent forefoot pain after Morton's neuroma resection.

High-Resolution Ultrasound of the Forefoot and Common Pathologies

Forefoot pain is common in clinical practice. Careful history taking and routine physical examination are initially performed for diagnosis, but imaging can confirm the clinical suspicion and play a key role in management. Ultrasound (US) can provide a visualization of the fine anatomy of the forefoot and is a useful method for evaluating various lesions causing forefoot pain. In this review, we provide the detailed anatomical structures of the forefoot and their normal appearances on US. We also focus on the most common pathologies affecting the forefoot, including plantar plate tear, sesamoiditis, bone fracture, synovitis, tenosynovitis, bursitis, Morton’s neuromas, and foreign bodies.

Neurologic Disorders Affecting the Foot and Ankle

The neurologic causes of foot and leg dysfunction are reviewed. Disorders causing foot and ankle pain, weakness, or other sensorimotor disturbances often cause difficulty with ambulation and prompt patients to seek medical evaluation. Physical signs and symptoms along with targeted diagnostic testing are needed to come to the correct diagnosis and treatment plan. An overview of peripheral nerve, muscle, and central nervous system disorders affecting the foot and leg are discussed.

A problem-based approach in musculoskeletal ultrasonography: central metatarsalgia

Ultrasonography (US) is a useful diagnostic method that can be easily applied to identify the cause of metatarsalgia. The superficial location of structures in the foot, dynamic capability of US, and the ability to perform direct real-time evaluations of the pain site are also strong advantages of US as a modality for examining the foot. Moreover, knowing the possible pain sources to investigate when a patient has a specific site of pain will enhance the diagnostic quality of US, and will help radiologists to perform US efficiently and effectively. The purpose of this article is to review the common etiologies of metatarsalgia including Morton’s neuroma, plantar plate injury, synovitis, tenosynovitis, bursitis, and metatarsal fractures, and to discuss their US features.

Lesions of the heel fat pad

OBJECTIVE

The heel fat pad (HFP) is a specialized soft tissue structure formed of adipose tissue that overlies the inferior and posterior aspect of the calcaneus and provides the cushioning effect of the heel. Lesions of the HFP are rare and can be a cause of debilitating heel pain that may often pose a challenge to clinicians. This study provides a series of lesions identified within the HFP.

METHODS AND MATERIALS

A retrospective review of heel pad lesions over a 12 year period was conducted at our tertiary orthopaedic oncology centre. All lesions of the heel fat pad were included in the study. Plantar fasciitis was excluded.

RESULTS

There were 17 heel pad lesions identified, of which the majority (n = 15) were benign.

CONCLUSION

We highlight a wide spectrum of pathologies that can occur in the HFP. Although rare, clinicians should be aware of these lesions, to initiate appropriate management.

Increased frequency of intermetatarsal and submetatarsal bursitis in early rheumatoid arthritis: a large case-controlled MRI study

Background

The forefoot is a preferential location for joint and tendon sheath inflammation in rheumatoid arthritis (RA). It also contains bursae, of which the intermetatarsal bursae have a synovial lining. Some small imaging studies suggested that intermetatarsal bursitis (IMB) and submetatarsal bursitis (SMB) are involved in RA, but their association has not been thoroughly explored. Healthy control studies suggested that lesion size might be relevant. We studied the relation between IMB and SMB in early RA, compared to other arthritides and healthy controls, and the relevance of lesion sizes.

Methods

Six hundred and thirty-four participants were studied: 157 consecutive patients presenting with early RA, 284 other arthritides, and 193 healthy controls. All underwent unilateral contrast-enhanced MRI of the forefoot at presentation. Two readers independently scored IMB and SMB and measured transverse and dorsoplantar diameters, blinded to clinical data. Subsequently, consensus was reached. Intra-reader ICC was 0.89. Logistic regression models were used, and test characteristics were calculated.

Results

IMB and SMB associated with RA independent of each other (P < 0.001) and independent of age, gender, BMI, RA-MRI inflammation, and anti-CCP-antibodies (P = 0.041). Sensitivity for RA of IMB was 69%, and for SMB 25%. Specificity for IMB was 70% compared to other arthritides, and 84% compared to healthy controls. For SMB, this was 94% and 97% respectively. Regarding lesion size, the groups had considerable overlap: no cut-off size for RA could be distinguished with high sensitivity and specificity.

Conclusion

Intermetatarsal and submetatarsal bursitis associated with early rheumatoid arthritis, contributing to the emerging evidence that inflammation of juxta-articular soft tissues is an early feature of RA.

A Rare Case of Lateral Forefoot Pain: Plantar Adventitious Bursitis

Forefoot pain is a common musculoskeletal complaint but is rarely caused by plantar adventitious bursitis. A 27-year-old female had right lateral forefoot pain for three weeks and was referred for an ultrasound examination, revealing an anechoic mass on top of the flexor digiti minimi brevis tendon. Two weeks after oral medication and a prescription of rocker-bottom shoes, her pain totally disappeared. In conclusion, ultrasound is helpful in differentiating various causes of forefoot pain, which, in this case, facilitated the detection and management of plantar adventitious bursitis.

Adventitious bursitis in the plantar fat pad of forefoot presenting as a tumoral mass

Adventitious bursitis of the plantar fat pad is a common cause of forefoot pain. It may develop at sites where subcutaneous tissue is exposed to friction and high pressure. In the forefoot, adventitious bursitis is usually adjacent to bony prominences of the metatarsal heads. Diagnosis and management of adventitious bursitis usually do not require imaging studies. However, the condition occasionally presents as a solid pseudotumoral mass requiring imaging. Magnetic resonance imaging (MRI) may demonstrate a heterogeneous mass with a solid component exhibiting intermediate to high signal intensity on T2-weighted images and thick nodular enhancement suggesting a neoplastic lesion. We report three cases of adventitious bursitis in patients who complained of a painful palpable mass on the forefoot, with a partially solid and enhancing component seen on MRI. In the first case, a biopsy was performed for the diagnosis of adventitious bursitis. The two other cases exhibited a solid component on MRI. However, a diagnosis of adventitious bursitis was suspected, and it was felt that a biopsy could be postponed. The spontaneous regression of the mass with relative discharge of the forefoot pressure confirmed the diagnosis. With these three cases, we illustrate the MR findings that could suggest adventitious bursitis despite the presence of a solid component and that may obviate the need for pathologic proof.

Ultrasound features of sole of foot pathology: a review

Foot pain is a common problem among adults, with approximately 19% of men and 25% of women describing significant daily foot pain that limits their ability to function. Older adults, the obese, and active adults participating in sports involving running and jumping are at increased risk of developing pathology. Problems affecting the sole of the foot are often the cause of pain. Ultrasound is an extremely useful method of quickly and accurately localizing and characterizing pathology of the foot. The wide availability of ultrasound combined with its low cost, lack of ionizing radiation, high spatial resolution, multiplanar capability and excellent patient tolerance makes it an ideal technique for assessing the superficial structures in the sole of the foot. Ultrasound has the advantage of dynamic assessment over other imaging modalities. Furthermore, Doppler interrogation allows a real-time assessment of vascularity, not possible using other techniques. The ability to perform extended field of view images allows improved image presentation, which has increased clinicians' acceptance of the technique. Finally, ultrasound can be used to guide interventional procedures. This review article will consider the ultrasound features of pathology commonly affecting the sole of the foot, and will describe MRI correlates that can be expected.

Foot pain is a common problem among adults, with approximately 19% of men and 25% of women describing significant daily foot pain that limits their ability to function. Older adults, the obese, and active adults participating in sports involving running and jumping are at increased risk of developing pathology. Problems affecting the sole of the foot are often the cause of pain. Ultrasound is an extremely useful method of quickly and accurately localizing and characterizing pathology of the foot. The wide availability of ultrasound combined with its low cost, lack of ionizing radiation, high spatial resolution, multiplanar capability and excellent patient tolerance makes it an ideal technique for assessing the superficial structures in the sole of the foot. Ultrasound has the advantage of dynamic assessment over other imaging modalities. Furthermore, Doppler interrogation allows a real-time assessment of vascularity, not possible using other techniques. The ability to perform extended field of view images allows improved image presentation, which has increased clinicians’ acceptance of the technique. Finally, ultrasound can be used to guide interventional procedures. This review article will consider the ultrasound features of pathology commonly affecting the sole of the foot, and will describe MRI correlates that can be expected.

Utility of power Doppler ultrasonography for detecting forefoot bursae in early rheumatoid arthritis: A case report

RATIONALE

Power Doppler ultrasonography (PDUS) in musculoskeletal ultrasound (MSUS) is a sensitive and reliable method for the assessment of rheumatoid arthritis (RA). The association between ultrasound-detectable forefoot bursae and the development of RA has gained attention. However, a few studies have evaluated the utility of PDUS for examining forefoot bursae in early RA. We report the case of an RA patient who developed reduced foot mobility and had detectable intermetatarsal bursitis with remarkable power Doppler (PD) signals in MSUS at the onset of RA.

PATIENT CONCERNS

A 40-year-old Japanese woman diagnosed with palindromic rheumatism visited our department due to sustained forefoot pain and difficulty walking. The levels of both rheumatoid factor (RF) and anticitrullinated protein antibody (ACPA) were high. She had opening toes with swelling in metatarsophalangeal (MTP) joints. PDUS showed intermetatarsal bursitis with mild MTP synovitis.

DIAGNOSES

We diagnosed RA by comprehensive judgment based on the 2010 American College of Rheumatology and European League Against Rheumatism classification criteria for RA.

INTERVENTIONS

We administered 6.0 mg/wk of methotrexate (MTX) and 2.0 mg/d of prednisolone (PSL) followed by an increase of MTX to 10 mg/wk.

OUTCOMES

After those treatments, the patient's symptoms showed improvement. As of this writing, the patient's remission has been maintained for >2 months.

LESSONS

Her case suggests that PDUS is useful for the detection of forefoot bursitis, and the detection of forefoot bursitis by PDUS may provide the opportunity to make an early diagnosis of RA.

Ultrasound evaluation of bursae: anatomy and pathological appearances

A bursa is an extra-articular sac that may communicate with a joint and functions to decrease friction between tendons and either bone or skin. Bursae can be classified as native and non-native (adventitious) bursae. The native bursae are lined with a synovial membrane and occur at predictable anatomical sites; knowledge of these normal structures can help distinguish them from other pathological entities. An adventitious bursa can form at sites of friction rather than at predictable anatomical sites, but otherwise have imaging features similar to native bursae. Bursal distention can occur from many pathological processes, most commonly resulting from chronic overuse injury. When imaging bursal pathological conditions, there is often an overlap of imaging findings, regardless of the cause. In general, ultrasound of a distended bursa reveals a fluid collection with either simple anechoic or more complex hypoechoic fluid. Bursal distention is characteristically unilocular and compressible, unlike other structures such as ganglion cysts, which are usually multilocular and non-compressible. This article reviews the anatomical locations of common bursae and shows pathological examples using ultrasound. Knowledge of typical locations and imaging appearances of bursae can aid in narrowing the differential diagnosis and guiding further management and treatment decisions.

Hypointense signals in the infrapatellar fat pad assessed by magnetic resonance imaging are associated with knee symptoms and structure in older adults: a cohort study

Background

There are few clinical and epidemiological studies reporting the association between abnormal changes within the IPFP and knee osteoarthritic changes. This study aims to describe the associations between hypointense signals in the infrapatellar fat pad (IPFP) and knee structural change and symptoms in older adults.

Methods

Participants (n = 874) were selected randomly from local community and followed up 2.7 years later (range 2.6–3.3 years). T1- or T2-weighted fat-suppressed magnetic resonance imaging (MRI) was assessed for IPFP hypointense signal, cartilage volume, cartilage defects, and bone marrow lesions (BMLs). Knee pain was assessed by self-administered Western Ontario and McMaster Osteoarthritis Index (WOMAC) questionnaire. Radiographic osteoarthritis was assessed using the OARSI atlas.

Results

Cross-sectionally, hypointense signals in the IPFP were significantly associated with a higher risk of knee cartilage defects at all sites, tibiofemoral BMLs and knee pain in multivariable analyses. Longitudinally, baseline signal abnormalities were significantly and positively associated with increases in knee cartilage defects (OR: 2.27, 95 % CI: 1.61–3.21), BMLs (OR: 1.91, 95 % CI: 1.39–2.62), and knee pain (OR: 1.36, 95 % CI: 1.05–1.76) in multivariable analyses. The associations with cartilage defects remained significant after adjustment for BMLs, but the associations with BMLs and knee pain decreased in magnitude or became non-significant after further adjustment for cartilage defects.

Conclusions

Hypointense signals in the IPFP were associated primarily with increased knee cartilage defects and also with BMLs and knee symptoms in cross-sectional and longitudinal analyses, suggesting the abnormality represented by this signal has a potentially important role in osteoarthritis progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1130-y) contains supplementary material, which is available to authorized users.

Ultrasound of the Gruberi Bursa With Cadaveric and MRI Correlation

OBJECTIVE

The purpose of this study was to describe the appearance and ultrasound characteristics of the Gruberi bursa using a cadaveric model and retrospective ultrasound imaging review.

MATERIALS AND METHODS

For the cadaveric study, ultrasound of the dorsolateral ankle of a foot-ankle specimen was performed and was followed by injection of latex between the extensor digitorum longus (EDL) tendons and the talus and dissection. For the ultrasound imaging review, the radiology database was searched for ultrasound studies performed from September 15, 2000, through April 1, 2015, to identify subjects with a dorsolateral foot or ankle fluid collection detected on ultrasound. Images were retrospectively reviewed to characterize the location and size of the fluid collection, assess for the number of locules, and evaluate the compressibility of the fluid collection. It was determined whether the ultrasound findings were significantly different from chance: CI and p values were obtained from performing a test for one proportion.

RESULTS

Dissection of a cadaveric specimen revealed latex within a well-defined region between the EDL tendons and the dorsolateral talus; this location is consistent with a Gruberi bursa. For the image review, the imaging examinations of 162 subjects (age range, 16-88 years; 31 male subjects and 131 female subjects) were reviewed. On the ultrasound images, a fluid collection with its epicenter between the dorsolateral talus and EDL was found in 93% of ankles. Of the fluid collections identified on ultrasound, 98% were unilocular and 94% were anechoic. Of these fluid collections, 133 were assessed for compressibility, and 89% were compressible. The positive findings for a Gruberi bursa that were different from chance (p < 0.0001) were a fluid collection being located between the EDL tendons and the dorsolateral talus and being unilocular, anechoic, and compressible.

CONCLUSION

The Gruberi bursa characteristically is located between the EDL and the talus; on ultrasound, the Gruberi bursa is most commonly unilocular, anechoic, and compressible.

[Acute sports injuries and chronic overuse stress damage to the forefoot and midfoot]

Sports injuries of the foot can occur as sequelae of acute trauma or chronic overuse. Besides clinical examination, imaging plays a major role in the detection of structural abnormalities and the differential diagnostics. This article reviews the most important sports-related soft tissue and bone pathologies of the forefoot and midfoot together with their typical findings on radiography, ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI).

MRI of lesser metatarsophalangeal joint plantar plate tears and associated adjacent interspace lesions

OBJECTIVE

To identify the variety of second and third intermetatarsal space (IS) lesions that may coexist with and without adjacent metatarsophalangeal joint (MTP) plantar plate (PP) tears.

MATERIALS AND METHODS

One hundred forefoot MRIs in 96 patients with metatarsalgia obtained between 30 September 2011 and 21 July 2012 using 1.5- or 3-T MRI were retrospectively reviewed in consensus by two MSK radiologists and one podiatrist (DPM). MRI was evaluated for second and third MTP PP tear and the presence/nature of second and third IS lesions. Second and third IS neuromas were measured in transverse (trans) dimension.

RESULTS

A total of 40 PP tears were identified: 36 at the second and 4 at the third MTP. Second MTP PP tear was identified in 33% of females and 40.5% of males. In the 63 female feet there were 21 second MTP PP tears, all of which also had second IS lesions: pericapsular fibrosis (16), bursitis (4), and ganglion (1). In the 37 male feet there were 15 second MTP PP tears, 14 of which had second IS lesions: pericapsular fibrosis (8), bursitis (5), and ganglion (1). There was no definite second IS neuroma adjacent to any second MTP PP tear. In females without PP tear, there were 24 second (3 mm trans average) and 43 third IS neuromas (4.1 mm trans average). In males without PP tear, there were 9 second (3.4 mm trans average) and 16 third IS neuromas (4.1 mm trans average).

CONCLUSIONS

MTP PP tears occurred in 40% of our cases, 90% of which occurred at the second MTP. Almost all coexisted with non-neuromatous second IS lesions.

The reliability of a novel magnetic resonance imaging-based tool for the evaluation of forefoot bursae in patients with rheumatoid arthritis: the FFB score

OBJECTIVE

The aim of this study was to determine the reliability of an MRI-based score that evaluates forefoot bursae (FFBs) in patients with RA.

METHODS

Items for inclusion, grading criteria and MRI sequences were determined iteratively. The score was evaluated in 30 patients with established RA. Reader agreement was evaluated using the percentage of exact/close agreement, Bland-Altman plots, kappa and intraclass correlation coefficient analyses.

RESULTS

The FFB score assesses nine forefoot regions and contains four items: presence, shape, enhancement and magnetic resonance characteristics. The FFB score showed moderate to good intra- and interreader agreement (κ range = 0.5-0.9 and 0.47-0.87, respectively).

CONCLUSION

The FFB score is adequately reliable in the evaluation of bursa-like lesions of the forefoot in patients with RA.

Morton's neuroma: clinical testing and imaging in 76 feet, compared to a control group

BACKGROUND

Morton's neuroma is a mechanically induced degenerative neuropathy.

METHODS

We compared clinical and MRI findings in 76 feet treated operatively for Morton's neuroma and 40 feet with different pathologies (controls).

RESULTS

In the 'treatment group' web space tenderness (WST) was positive in 95%, foot squeeze (SQU) in 88%, plantar percussion (PLP) in 61%, and toe tip sensation deficit (TTSD) in 67%. MRI identified neuromata in 97%. Histological examination confirmed neuroma excision in 99%. Frequency of positive tests was significantly higher in the treatment group compared to controls. MRI revealed (asymptomatic) neuromata in 10/40 (25%) feet in the control group. TTSD was similarly positive in asymptomatic and symptomatic neuromata. TTSD in association with any other test being positive, was significantly more frequent in symptomatic neuromata.

CONCLUSIONS

The diagnosis of Morton's neuroma, based on clinical and imaging findings, was accurate. Positive clinical testing was more frequent in the 'treatment' group compared to the 'control' group.

Pseudotumoural soft tissue lesions of the foot and ankle: a pictorial review

In the foot and ankle region, benign neoplasms and pseudotumoural soft tissue lesions are significantly more frequent than malignant tumours. The pseudotumoural lesions constitute a heterogeneous group, with highly varied aetiology and histopathology. This article reviews the imaging features of the most common pseudotumours of the soft tissues in the foot and ankle. Although the imaging characteristics of several of the lesions discussed are non-specific, combining them with lesion location and clinical features allows the radiologist to suggest a specific diagnosis in most cases.

Assessment of the natural history of forefoot bursae using ultrasonography in patients with rheumatoid arthritis: a twelve-month investigation

OBJECTIVE

To determine the natural history and clinical significance of forefoot bursae over a 12-month period in patients with rheumatoid arthritis (RA).

METHODS

Patients with RA (n=149) attending rheumatology outpatient clinics were assessed at baseline. A total of 120 participants, mean±SD age 60.7±12.1 years and mean±SD disease duration 12.99±10.4 years, completed the 12-month followup (98 women, 22 men, 93 rheumatoid factor positive, 24 rheumatoid factor negative, and 3 unknown). Musculoskeletal ultrasound (US) was used to identify forefoot bursae in all of the participants. Clinical markers of disease activity (well-being visual analog scale [VAS], erythrocyte sedimentation rate [ESR], C-reactive protein [CRP] level, and Disease Activity Score in 28 joints [DAS28]) and foot symptoms on the Leeds Foot Impact Scale (LFIS) Questionnaire were recorded on both occasions.

RESULTS

Presence of US-detectable forefoot bursae was identified in 93.3% of returnee (n=120) participants (individual mean 3.7, range 0-11) at baseline. Significant associations were identified between bursae presence and patient-reported foot impact for impairment/footwear (LFISIF ; baseline: r=0.226, P=0.013 and 12 months: r=0.236, P=0.009) and activity limitation/participation restriction (LFISAP; baseline: r=0.254, P=0.005 and 12 months: r=0.235, P=0.010). After 12 months, 42.5% of participants had an increase in the number of US-detectable forefoot bursae and 45% of participants had a decrease. Changes in bursae number significantly correlated with changes in LFISIF (r=0.216, P=0.018) and LFISAP (r=0.193, P=0.036). No significant associations were identified between changes in bursae and changes in global well-being VAS, ESR, CRP level, or DAS28.

CONCLUSION

The findings of this study suggest that forefoot bursae may regress or hypertrophy over time in patients with RA, and that these changes may be associated with self-reported foot impairment and activity restriction.

Morton neuroma: MR imaging after resection--postoperative MR and histologic findings in asymptomatic and symptomatic intermetatarsal spaces

PURPOSE

To evaluate the prevalence of postoperative magnetic resonance (MR) imaging findings in asymptomatic and symptomatic patients after resection of Morton neuroma.

MATERIALS AND METHODS

This study was approved by the institutional review board. Informed consent was obtained from each participant. Fifty-eight consecutive patients (46 women, 12 men) who had undergone resection of a painful Morton neuroma (90 Morton neuromas were removed in 66 feet), pre- and postoperative MR imaging, and clinical follow-up for a minimum of 2 years after surgery were identified. Two experienced musculoskeletal radiologists evaluated MR images with regard to the presence of presumed recurrent Morton neuroma, scar, or intermetatarsal bursitis. The prevalence of abnormalities in asymptomatic and symptomatic intermetatarsal spaces was determined. The results of the second radiologist were used only to determine interobserver reliability. The kappa statistics were obtained to assess interobserver agreement. Seven patients with presumed recurrent Morton neuroma underwent repeat surgery.

RESULTS

Clinically speaking, 68 intermetatarsal spaces (44 of 58 patients [76%], 47 feet) were asymptomatic at follow-up and 22 (14 of 58 patients [24%], 19 feet) were symptomatic. A presumed Morton neuroma was found in 18 (26%) of the asymptomatic spaces and 11 (50%) of the symptomatic spaces. A presumed scar was found in six (9%) of the asymptomatic spaces and two (9%) of the symptomatic spaces. A presumed intermetatarsal bursitis was found in six (9%) of the asymptomatic spaces and six (27%) of the symptomatic spaces. Interobserver agreement for presumed recurrent Morton neuroma was substantial (kappa = 0.64). Histologic examination of presumed recurrent Morton neuroma revealed fibrous tissue but no sign of peripheral neural tissue.

CONCLUSION

MR imaging after Morton neuroma resection commonly reveals Morton neuroma-like abnormalities in asymptomatic and symptomatic intermetatarsal spaces.

Improvement in symptoms and signs in the forefoot of patients with rheumatoid arthritis treated with anti-TNF therapy

Background

Inhibition of tumour necrosis factor (TNF) is an effective way of reducing synovitis and preventing joint damage in rheumatoid arthritis (RA), yet very little is known about its specific effect on foot pain and disability. The aim of this study was to evaluate whether anti-TNF therapy alters the presence of forefoot pathology and/or reduces foot pain and disability.

Methods

Consecutive RA patients starting anti-TNF therapy (infliximab, etanercept, adalimumab) were assessed for presence of synovial hypertrophy and synovitis in the 2^nd and 5^th metatarso-phalangeal (MTP) joints and plantar forefoot bursal hypertrophy before and 12 weeks after therapy. Tender MTP joints and swollen bursae were established clinically by an experienced podiatrist and ultrasound (US) images were acquired and interpreted by a radiologist. Assessment of patient reported disease impact on the foot was performed using the Manchester Foot Pain and Disability Index (MFPDI).

Results

31 patients (24 female, 7 male) with RA (12 seronegative, 19 seropositive) completed the study: mean age 59.6 (SD 10.1) years, disease duration 11.1 (SD 10.5) years, and previous number of Disease Modifying Anti Rheumatic Drugs 3.0 (1.6). Significant differences after therapy were found for Erythrocyte Sedimentation Rate (t = 4.014, p < 0.001), C-reactive protein (t = 3.889, p = 0.001), 28 joint Disease Activity Score (t = 3.712, p = 0.0001), Visual Analog Scale (t = 2.735, p = 0.011) and Manchester Foot Pain and Disability Index (t = 3.712, p = 0.001).

Presence of MTP joint synovial hypertrophy on US was noted in 67.5% of joints at baseline and 54.8% of joints at twelve weeks. Presence of plantar forefoot bursal hypertrophy on US was noted in 83.3% of feet at baseline and 75% at twelve weeks. Although there was a trend for reduction in observed presence of person specific forefoot pathology, when the frequencies were analysed (McNemar) this was not significant.

Conclusions

Significant improvements were seen in patient reported foot pain and disability 12 weeks after commencing TNF inhibition in RA, but this may not be enough time to detect changes in forefoot pathology.

MR arthrography of the second and third metatarsophalangeal joints for the detection of tears of the plantar plate and joint capsule

OBJECTIVE

Tears of the plantar plate and joint capsule of the metatarsophalangeal joint are underrecognized causes of lesser metatarsalgia. This study evaluated MR arthrography for evaluation of this condition in 45 metatarsophalangeal joints in 41 patients.

CONCLUSION

Most metatarsophalangeal joint capsular tears occur at the distal lateral border of the plantar plate, often with injury of the adjacent interosseous tendon. Plantar plate tears are less common. MR arthrography of the metatarsophalangeal joint delineates capsular tears and associated abnormalities.

Soft-tissue tumors and tumorlike lesions: a systematic imaging approach

Soft-tissue lesions are frequently encountered by radiologists in everyday clinical practice. Characterization of these soft-tissue lesions remains problematic, despite advances in imaging. By systematically using clinical history, lesion location, mineralization on radiographs, and signal intensity characteristics on magnetic resonance images, one can (a) determine the diagnosis for the subset of determinate lesions that have characteristic clinical and imaging features and (b) narrow the differential diagnosis for lesions that demonstrate indeterminate characteristics. If a lesion cannot be characterized as a benign entity, the lesion should be reported as indeterminate, and the patient should undergo biopsy to exclude malignancy.

Cellular and histopathological changes in the infrapatellar fat pad in the monoiodoacetate model of osteoarthritis pain

OBJECTIVE

The infrapatellar fat pad (IPFP) has been identified as a source of anterior knee pain. Fibrosis and marked inflammatory infiltrate in the IPFP of patients with arthritis of the knee and reduction in pain post knee replacement in patients following resection of the IPFP have been observed. We have investigated changes in the IPFP of rats undergoing the monoiodoacetate (MIA) model of degenerative joint disease, a model that exhibits some histopathological similarities to osteoarthritis (OA).

METHODS

Rats were injected intra-articularly with MIA and the development of weight bearing asymmetry was followed for 21 days as compared to vehicle-injected animals. In addition, IPFPs were removed from both ipsilateral and contralateral joints. Both inflammatory infiltrate and histopathological changes were analysed.

RESULTS

MIA injection caused marked weight bearing asymmetry. Ipsilateral IPFP wet weights were significantly increased on days 1 and 3 in MIA-treated animals. MIA treatment also resulted in significant increases in IPFP total white blood cells and monocytes on days 1, 3, and 7 and neutrophils on days 1 and 3. This was supported by histopathological findings at early time points which progressed to adipocyte necrosis, IPFP fibrosis, patellar cartilage and subchondral bone necrosis with synovial hyperplasia at later timepoints.

CONCLUSIONS

The current study clearly demonstrated that marked inflammatory changes in the IPFP occur during the early stage of the MIA model of OA which may contribute to the pain observed at this early stage. The role of the IPFP in later stages of the model needs to be further explored.