point-of-care ultrasonography in a physiatric foot clinic

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European Journal of Physical and Rehabilitation Medicine 2017 February;53(1):72-80 DOI: 10.23736/S1973-9087.16.04141-1

ORIGINAL ARTICLE

Point-of-care ultrasonography in a physiatric foot clinic Se W. LEE 1 *, Dennis D. J. KIM 1, Phuong LE 1, Mathew N. BARTELS 1, Mooyeon OH-PARK 2 1Montefiore

Medical Center, New York City, NY, USA; 2Kessler Institute for Rehabilitation, Rutgers New Jersey Medical School, West Orange, NJ, USA

*Corresponding author: Se W. Lee, Montefiore Medical Center, New York City, NY, USA. E-mail: [email protected]

ABSTRACT BACKGROUND: Few reports are available for the utility of diagnostic point-of-care (POC) ultrasonography for foot and ankle pain and diagnostic POC ultrasonography in physiatric practice has not yet been demonstrated. AIM: To describe POC musculoskeletal ultrasonographic (US) findings by location of pain among patients presenting to a foot pain clinic and to evaluate the concordance rate between clinical diagnoses and US findings by region of the foot. DESIGN: Retrospective chart review. SETTING: Outpatient clinic. POPULATION: A total of 111 patients with foot and ankle pain. METHODS: Retrospective chart review of clinical notes and data from POC US evaluation of patients who presented to the foot pain clinic between November 2013 and January 2015. US evaluations were performed by two physiatric ultrasonographers. MAIN OUTCOME MEASURES: The concordance rate of clinical diagnosis and findings from US imaging based on the location of foot pain. RESULTS: One hundred eleven patients out of 205 patients who presented to the foot clinic (54.1%) had POC US evaluation during the initial visit. The data was analyzed for patients with a single location of pain excluding 21 patients with pain more than one location. The mean age was 55.1±14.3 years with 86.5% being female. The most common location of pain was the hindfoot/ankle (N.=71), followed by forefoot (N.=13) and midfoot (N.=6). The overall concordance rate between clinical and ultrasonographic diagnoses was 62.2% (56/90) with a higher concordance rate in the hindfoot (67.6%) compared to the rest of the foot (50% in midfoot, 38.5% in the forefoot, P=0.042). The most common reasons for discordance (N.=34) were failure to reveal abnormality on US (N.=20, 58%) followed by unexpected US findings (N.=7, 20.6%). CONCLUSIONS: Concordance between clinical evaluation and POC US findings varies depending on the location of foot pain and often no US abnormalities were found in spite of clinical symptoms particularly in forefoot region. CLINICAL REHABILITATION IMPACT: These new findings will enhance the selective application of POC US and improve its clinical utility in physiatric practice. (Cite this article as: Lee SW, Kim DDJ, Le P, Bartels MN, Oh-Park M. Point-of-care ultrasonography in a physiatric foot clinic. Eur J Phys Rehabil Med 2017;53:72-80. DOI: 10.23736/S1973-9087.16.04141-1) Key words: Point-of-care systems - Ultrasonography - Foot - Pain - Diagnostic imaging.

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oot pain is frequently encountered in physiatric practice with a wide spectrum of musculoskeletal and neurovascular structures as pain generators.1, 2 Although clinical evaluation provides important clues for accurate diagnosis, it is often challenging to identify the exact nature and distribution of the pathology due to the close proximity of anatomical structures in the foot.3 Furthermore, positive physical examination findings including identification of typical tender points or provocative tests for specific diagnoses may not be

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present in cases with definite but minimal involvement of the structures.3, 4 Hence, the utilization of appropriate imaging studies may enhance the correct identification of pain generating structures. Recently, ultrasonography (US) has been widely advocated for its use in evaluating musculoskeletal and neuromuscular disorders as it provides a high resolution, cost effective, and office-based readily available imaging. Since most structures of the foot and ankle are superficial, ultrasonography is a particularly useful di-

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agnostic tool even in obese individuals. Other advantages of using US include real-time, dynamic assessment, the flexibility in the field-of-view, and the opportunity for comparison with the asymptomatic side. Shortcomings of US include limited ability to evaluate for bone marrow (intracortical) and intra-articular lesions 5 and operator dependence; however, the latter can be addressed through proper training and practice.6 Ultrasonography has been rapidly accepted as a preferred modality for guiding interventions.7, 8 However, the role of point-of-care (POC) ultrasonography in physiatric practice, defined as US performed and interpreted by the clinician at the bedside as an extension of the clinical examination in enhancing diagnostic accuracy, guiding patient care, and improving outcomes, has been limited to inpatient neurorehabilitaiton setting.9-12 There have been only scarce reports of the utility of diagnostic POC US in musculoskeletal practice.13-16 Clinical utility of POC diagnostic US has been studied for several rheumatologic conditions in enhancing the primary diagnosis and acute traumatic conditions in reducing the need of ordering standard X-ray.15, 17, 18 Considering the increasing emphasis on the evidence-based and costconscious practice in the current healthcare system, it will be critical to assess the impact of the wide-spread use of US on care and outcome in physiatric musculoskeletal practice.18 The aim of this retrospective study was to describe the POC US findings by the location of foot pain among patients who presented to foot pain clinic and to evaluate the pattern of diagnostic concordance between clinical diagnosis and US findings. Materials and methods Patient and clinical examination The electronic medical records of all patients who presented to the Physical Medicine and Rehabilitation (PM&R) Foot Clinic between November 2013 and January 2015 were reviewed. The patients with foot or ankle pain who received POC US evaluation during this period were included in the study. Demographic information including age, sex, height, weight, Body Mass Index (BMI), past medical/surgical history, intensity of pain (on a numeric rating scale) were obtained. Location of pain and point of maximal tenderness were categorized into forefoot, midfoot, hindfoot/

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ankle regions. The forefoot was defined as distal to the tarsal-metatarsal joint and hindfoot was defined as proximal to the transverse tarsal joints (Chopart joint) including the talus and calcaneus.19 The forefoot region was further divided into medial and lateral segments; and the hindfoot into medial (including dorsal-medial), lateral (including dorsal-lateral), posterior and plantar segments. The midfoot included the navicular, cuboid, and the three cuneiform bones with tarso-metatarsal (Lisfranc) joints.20 The medial forefoot included the 1st and 2nd rays. Clinical diagnosis was made prior to POC US, based on comprehensive history and physical examination (including inspection, systemic palpation of foot structures, and specific provocative maneuvers) conducted by physiatrists with expertise and experience in managing painful foot disorders. The case definitions for common clinical diagnoses are described in the Table I.8, 20-26 The physiatrist ultrasonographers were not blinded to the clinical diagnoses as indicated by POC US. Ultrasound evaluation Point of care ultrasonography evaluation was performed during the initial visit to the foot clinic among patients with clinically suspected pathologies of tendon, ligament, joint, cortical bone (e.g., stress fracture), soft tissue mass/neuroma, or plantar fascia. Ultrasonography was not performed in patients who were suspected to have diffuse peripheral neuropathy, ischemic pain, or pathologies of bone marrow (e.g., osteochondritis dissecans, avascular necrosis), or skin (e.g., callus). US evaluation was done after clinical examination using a high frequency (12 MHz) linear probe (General Electric Healthcare, Milwaukee, WI, USA), limited to the region of interest based on the location of pain indicated by the patient as well as the clinical diagnoses provided by the examining physician. All POC US examinations were done by one of two physiatrists certified by the American Registry for Diagnostic Medical Sonography, with more than 5 years of experience in diagnostic ultrasonography and management of foot disorders. The definition of abnormal ultrasound findings of pathologic lesions follows Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) consensus criteria.27 US definitions for common pathologies include loss of normal fibrillar architecture, abnormally heterogenic or

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Table I.—Case definitions of common clinical diagnoses.8, 20-26 Foot region

Lateral hindfoot/ankle

Clinical diagnosis

Lateral ankle sprain Peroneal tendinopathy

Medial hindfoot/ankle

Posterior tibialis dysfunction

Posterior heel/ankle

Achilles tendinopathy/tear Insertional Achilles tendinopathy

Plantar heel

Plantar fasciitis

Midfoot

Midfoot arthritis

Forefoot

Primary metatarsalgia 2nd MTPJ subluxation

Case definition

History of inversion ankle injury with pain and tenderness at the distal tip of the lateral malleolus, positive provocative test (one of anterior drawer, talar tilt with ankle plantarflexion, anterolateral drawer test).21 Pain and tenderness on the peroneal tendon at the retromalleolar groove and/or between lateral malleolus and cuboid. Pain and apprehension with resisted ankle eversion, forced inversion and/or 1st ray plantarflexion.22 Pain and tenderness on posterior tibialis tendon between the medial malleolus and navicular aggravated by resisted ankle inversion, positive single or double heel rise test with/ without lateral hindfoot pain, pes planovalgus deformity and 1st metatarsal rise sign.23 Pain and tenderness on the Achilles tendon 2-6 centimeters from the insertion to calcaneus and thickened tendon with/without palpable gap, positive Thompson sign, or Matles test (in rupture).24 Pain and tenderness on the posterior calcaneal tuberosity without signs of retrocalcaneal bursitis (bulging, warmth and/or erythema on the lateral border of the Achilles tendon) with/without Haglund deformity.24 Pain and tenderness on the medial tuberosity of the calcaneus (origin of the plantar facsia), worsened with walking and/or upon arising in the morning and by the windlass mechanism (dorsiflexing metatarsophalangeal joints).8 Pain and tenderness on the midfoot joints (tarso-metatarsal joint), typically aggravated by standing and walking, relieved by resting with or without palpable bony prominence, and effusion.20 Pain and tenderness on the lateral forefoot (3rd to 5th) without the signs of other common forefoot pathologies such as inflammatory arthropathy, foot deformity interdigital neuritis (Mulder’s click, pinch test or sensory disturbance of the web space).25 Pain and tenderness on the plantar aspect of 2nd metatarsophalangeal joint, deviation of 2nd toe with/without overlying toe deformity.26

hypoechoic and/or thickened tendon in 2 perpendicular planes for tendinopathy, hypoechoic or anechoic thickened tissue with or without fluid within the tendon sheath in 2 perpendicular planes for tenosynovitis, abnormally hypoechoic and/or thickened tendon or ligament at bony attachment in 2 perpendicular planes for enthesopathy. US findings for each case were compared to the corresponding clinical diagnosis at each region of the foot. Patients with a single location of pain were included for concordance evaluation. If there were multiple clinical diagnoses made for the specific region, the status of concordance was evaluated based on the comparison of the US imaging with the primary clinical diagnosis for the foot pain.28 The patients were grouped into concordant diagnosis group and discordant diagnosis group. For the discordant group, further analysis was conducted to examine the pattern of discordance such as significant pathology identified in US but not anticipated from clinical evaluation, failure to identify significant structural pathology on US, or others (i.e. incidental finding without clinical significance).29

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Statistical analysis The percent distribution of tenderness localized to the forefoot (medial/lateral), the midfoot, hindfoot/ankle (medial, lateral, posterior and plantar) was reported. Absolute frequencies of clinical diagnosis in each of these areas of the foot were reported. The concordance and discordance rate between the clinical diagnosis and the ultrasound findings were reported as percentages. Proportion of discordant cases among different regions of the foot was analyzed using the χ2 test. Results Two hundred and five new patients were seen in the PM&R foot clinic from November 2013 to January 2015. The majority of patients were referred from primary care physicians (33.6%), podiatrists/orthopedists (31.8%), and other physiatrists (30.6%). One hundred and eleven patients out of 205 (54.1%) underwent diagnostic ultrasonography during their initial visits to foot clinic. Unavailability of physiatric ultrasonographer

European Journal of Physical and Rehabilitation Medicine February 2017


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Table II.—Patient demographics. Characteristics

Age (range), years Gender, female Race or ethnicity White Black Others Body Mass Index (kg/m2) Total sample Men Women Pain intensity (NRS 0-10) Total sample Men Women

Sample (N.=111)

55.1±14.3 (20 to 90) 96 (86.5%) 12 (10.8%) 37 (33.3%) 62 (55.9%) 33.0±5.8 28.7±3.7 33.6±5.8 6.2±2.1 6.2±2.2 6.2±2.0

Continuous variables presented as mean ± standard deviation or as absolute number (percentage). NRS: Numeric Rating Scale.

Table III.—Distribution of location of foot pain among patients as classified at time of clinic visit. Location of foot pain

Forefoot Medial Lateral Medial and lateral Midfoot Hindfoot/ankle Lateral Medial Plantar heel Posterior heel/ankle Multiple ≥2

Total sample (N.=111)

13 (11.7%) 7 (6.3%) 5 (4.5%) 1 (0.9%) 6 (5.4%) 71 (63.0%) 31 (27.0%) 12 (10.8%) 16 (14.4%) 12 (10.8%) 21 (18.9%)

(N.=46/94) and ultrasound machine (N.=45/94) during the initial visits were the main reasons why POC US examination was not performed. Three patients did not have US examinations due to open wound. The mean age of patients was 55.1±14.3 years with 86.5% being female (Table II). The most common location of pain was the hindfoot/ankle (N.=71, 63.0%), followed by forefoot (N.=13, 11.7%) and midfoot (N.=6, 5.4%). The distributions of pain are seen in Table III. Plantar fasciitis (N.=24, 21%) was the most common clinical diagnosis followed by lateral ankle sprain (N.=20, 18%) and insertional Achilles tendinopathy (N.=10, 9%). Tibialis posterior tendon dysfunction was the most common clinical diagnosis in the medial hindfoot, midfoot arthritis in the midfoot, and metatarsalagia in the forefoot. Twenty-six patients (23%) did not show any abnormalities in POC US. Common US findings included statistically significant unilateral plantar fascia thickening (N.=17, 20%, 7.3±1.6 mm in symptomatic vs. 4.6±1.1 mm in asymptomatic side, P