Metatarsalgia: An ultrasound perspective

Foot pain in children and adolescents: a problem-based approach in musculoskeletal ultrasonography

Various etiologies and risk factors contribute to foot pain in children and adolescents, including conditions such as Kohler's disease, Sever's disease, Iselin's disease, rigid flat foot, accessory navicular, Freiberg's disease, sesamoiditis, os trigonum syndrome, and more. High-frequency musculoskeletal ultrasonography can show both the bone surface and the surrounding soft tissue clearly from various angles in real-time, thereby providing a higher level of detail that is helpful for identifying the etiology of foot pain and monitoring disease progression compared with other imaging modalities. This review provides an overview of the epidemiology, pathophysiology, clinical manifestations and characteristic ultrasonographic findings of select foot pain conditions in children and adolescents.

High-resolution Ultrasound of the Foot and Ankle

High-resolution ultrasound (US) can be used to assess soft tissue abnormalities in the foot and ankle. Compared to MRI, it has lower cost, is widely available, allows portability and dynamic assessment. US is an excellent method to evaluate foot and ankle tendon injuries, ligament tears, plantar fascia, peripheral nerves, and the different causes of metatarsalgia.

First Metatarsophalangeal Joint Pain in Athletes: Diagnosis, Management, and Return to Play Considerations

ABSTRACT

The first metatarsal-phalangeal joint plays a key role for athletes of various disciplines. When an athlete presents for evaluation of pain at this joint, there are several causes that should be considered. The purpose of this article is to review common injuries including turf toe, sand toe, extensor and flexor hallucis longus tendinopathy, sesamoiditis, and metatarsalgia and provide current evidence-based recommendations for diagnosis, management, and return to play considerations. Conditions not specific to athletes like gout and hallux rigidus also are discussed. Mechanism of injury, physical examination, and imaging such as weight-bearing radiographs and point-of-care ultrasound can help with diagnosis. Treatment of many of these injuries begins with nonsurgical management strategies including footwear or activity modification, physical therapy, and select interventions.

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.

Static Versus Dynamic Musculoskeletal Ultrasound for Detection of Plantar Plate Pathology

Musculoskeletal ultrasound (US) is a common modality used to examine plantar plate pathology. Comparison of the diagnostic accuracy of static versus dynamic ultrasound has not been previously published. The objective of this study was to prospectively compare the value of using preoperative static and dynamic ultrasound findings to diagnose plantar plate pathology using intraoperative inspection as the standard of reference. Patients attending a single foot and ankle specialty clinic from August 2012 to June 2013 with clinically suspected plantar plate pathology that was unresponsive to conservative care served as the study population. Static and dynamic ultrasound exams were performed by a single experienced rater and compared to intraoperative findings. The overall accuracy, sensitivity, specificity, positive predictive value and negative predictive value were determined for static and dynamic ultrasound exams. Thirty-six patients (45 lesser metatarsophalangeal joints) were included in this analysis. Of the 36 patients, 29 were females and 7 were males with average age of 57.9 ± 7.8 years (range, 38-73). There were 38 plantar plate tears (84.4%) noted on intraoperative examination. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for the static US exam were 80.0%, 81.6%, 71.4%, 93.9%, and 41.7%, respectively. The same values for the dynamic US exam were 88.9%, 100%, 28.6%, 88.3%, and 100%, respectively. Static and dynamic ultrasound techniques are each highly sensitive methods for assessing plantar plate pathology. However, the sensitivity and accuracy of the exam is best when dynamic assessment of the plantar plate is employed. Caution should be used when relying solely on static images to diagnose subtle injuries in this area of the foot.

LEVELS OF EVIDENCE

Diagnostic Level II, Prospective.

Forefoot: a basic integrated imaging perspective for radiologists

Imaging of the forefoot is increasingly requested for patients with metatarsalgia. Awareness with specific anatomic arrangements exclusive for the forefoot and widely variable pathologic entities associated with metatarsalgia helps the radiologist to tailor a cost-effective imaging approach. This will enable reaching a specific diagnosis as much as possible with subsequent proper patient management. This pictorial review aims to provide basic understanding for the different imaging modalities used in studying the forefoot. After that, certain anatomic arrangements exclusive for the forefoot are discussed. The final section of this review describes the imaging findings of some common forefoot problems.

Musculoskeletal ultrasound for preoperative imaging of the plantar plate: a prospective analysis

The purpose of this study was to prospectively compare preoperative findings on musculoskeletal ultrasound evaluation to observed intraoperative findings for patients undergoing surgical correction of plantar plate tears. Fifty consecutive patients with forefoot pain and a suspected unilateral plantar plate tear at the second metatarsophalangeal (MTP) joint were identified. The same examiner performed a 2-plane (longitudinal and transverse) musculoskeletal ultrasound on the painful second MTP joint. The contralateral second MTP joint was used for comparison. Longitudinal ultrasound images were graded as "torn" or "intact." Transverse ultrasound images were used to localize the suspected pathology. Results of the ultrasound were compared with observed intraoperative pathology. Forty-five plantar plate tears were identified intraoperatively. Longitudinal ultrasound images correctly identified 40 plantar plate tears. The longitudinal ultrasound had a sensitivity of 91.1%, a specificity of 25%, a positive predictive value of 91.1%, and a negative predictive value of 25%. Transverse ultrasound images identified 36 plantar plate tears correctly localizing only 19 tears. Musculoskeletal ultrasound has been widely used to identify and localize pathology in many soft tissue structures. Whereas the longitudinal ultrasound images were useful in identifying plantar plate tears, the same cannot be said about the ability to localize the tear on the transverse ultrasound images. Therefore, ultrasound may not be as good an imaging modality as magnetic resonance imaging for identification and localization of plantar plate pathology.

The underlying osseous deformity in plantar plate tears: a radiographic analysis

PURPOSE

Plantar plate tears can cause pain and deformity of the forefoot. The purpose of this study is to correlate common radiographic findings with observed intra-operative pathology in patients with plantar plate pathology.

METHODS

Bilateral weight-bearing radiographs were reviewed for 88 patients (106 feet) who underwent surgical repair of suspected plantar plate pathology. Parameters reviewed included the first intermetatarsal angle, the metatarsus adductus angle, the second and third metatarsophalangeal angles, splaying of the second and third toes, evaluation of the metatarsal parabola by 3 different methods, the first and second lateral declination angles, and the second lateral metatarsophalangeal angle.

RESULTS

Of 106 feet, 97 had intra-operative plantar plate tears. The radiographs of patients with plantar plate tears had an increased amount of digital splay on the anteroposterior radiograph compared to patients without pathology. For patients with unilateral plantar plate pathology, the metatarsal parabola of the symptomatic foot was compared with that of the asymptomatic foot. A significantly increased second metatarsal protrusion distance as measured by 2 different methods was noted in the symptomatic foot. Odds ratios revealed that patients with an intermetatarsal angle >12, medial deviation of the second toe, and splaying of the digits were more likely to be diagnosed with a plantar plate tear intra-operatively.

CONCLUSION

Although radiographs do not definitively diagnose plantar plate tears, understanding osseous forefoot architecture will aid with diagnosis in the absence of other osseous pathology. Furthermore, these data suggest that parabola should be corrected to maintain long-term correction of plantar plate pathology.

LEVEL OF EVIDENCE

Prognostic, Level II.

Magnetic resonance imaging versus musculoskeletal ultrasound for identification and localization of plantar plate tears

PURPOSE

Plantar plate injuries have been identified as a cause of forefoot pain and deformity. Magnetic resonance imaging (MRI) and musculoskeletal ultrasound (US) have been suggested as appropriate imaging modalities for this pathology. A comparison of these two modalities utilizing intra-operatively pathology as the reference standard has not been published.

METHODOLOGY

51 feet of 42 consecutive patients presenting to clinic with forefoot pain and a suspected unilateral plantar plate tear at the 2nd metatarsophalangeal (MTP) joint were identified. A two plane (longitudinal and transverse) US was performed on the painful second MTP joint. Longitudinal ultrasound images were graded as 'torn' or 'intact'. Transverse ultrasound images were used to localize pathology. All ultrasound exams were performed by the same reconstructive foot & ankle fellow. A pre-operative MRI was performed on these patients and read by a Fellowship Trained Musculoskeletal Radiologist. The physicians reading US and the MRI were blinded to each other's findings.

RESULTS

All 51 feet were examined intra-operatively. 46 plantar plate tears were identified. The sensitivity, specificity, positive predictive value and negative value of MRI were 73.9%, 100%, 100%, 29.4% respectively while the same values for US were 91.5%, 25%, 91.5%, 25% respectively. MRI identified 4 collateral ligaments tears not identified on ultrasound. Discussion &

CONCLUSIONS

Both MRI and US are appropriate modalities for imaging of the plantar plate. While US is a highly sensitive exam, MRI is a more specific exam. Overall these results do not suggest that MR should be replaced by US in all cases.

LEVEL OF EVIDENCE

Diagnostic, Level I.