Pediatr Radiol (2007) 37:1118–1124 DOI 10.1007/s00247-007-0581-3
ORIGINAL ARTICLE
Focused dynamic sonographic examination of the congenital clubfoot William E. Shiels II & Brian D. Coley & John Kean & Brent H. Adler
Received: 14 May 2007 / Revised: 24 June 2007 / Accepted: 5 July 2007 / Published online: 4 September 2007 # Springer-Verlag 2007
Abstract Background US readily demonstrates cartilaginous structures, and static sonography has shown potential in evaluating clubfoot deformity. Objective To investigate the potential of dynamic sonography in the evaluation of the congenital clubfoot. Materials and methods Sonography was used for static and dynamic stress evaluation of 13 clubfeet and 35 normal feet in 24 patients (ages 0–32 weeks). Dynamic foot sonography was performed using a single-operator bimanual scanning technique. The examination involved coronal oblique evaluation of the medial malleolar–navicular (MMN) distance and the calcaneocuboid relationship, sagittal evaluation of the talonavicular relationship, and transverse evaluation of navicular subluxation, rotation, and deformation. Dynamic abduction/adduction stress maneuvers were performed, measured by the MMN. Results The clubfoot “gristle” is a consistent, measurable soft-tissue landmark in clubfeet, connecting the medial malleolus to the medial navicular and talus. Mean MMN distances in clubfeet in the neutral position and abduction were significantly different from these distances in the W. E. Shiels II : B. D. Coley : B. H. Adler Children’s Radiological Institute, Department of Radiology, Columbus Children’s Hospital, Columbus, OH, USA J. Kean Department of Orthopedic Surgery, Columbus Children’s Hospital, Columbus, OH, USA W. E. Shiels II (*) Department of Radiology, Columbus Children’s Hospital, 700 Children’s Drive, Columbus, OH 43205 USA e-mail:
[email protected]
normal paired foot (differences of 8.7 mm neutral position and 7.94 mm abduction), as compared to bilateral normal feet (differences of 0.98 mm neutral position and 1.43 mm abduction). Navicular subluxation showed good correlation between highly deformed and subluxated navicular bones and a tight medial clubfoot complex. Conclusions Focused dynamic foot sonography is useful in providing a specific and detailed functional preoperative and/or postoperative assessment of the congenital clubfoot. Keywords Clubfoot . US . Sonography . Musculoskeletal . Foot deformity . Children
Introduction Congenital clubfoot (congenital talipes equinovarus, CTEV) is a common congenital foot deformity occurring in 0.5–7 per 1,000 live births, depending upon the population studied [1]. The primary abnormality is medial and plantar rotational malposition of the navicular on the head of the talus, with anterior malposition of the medial malleolus (MM) overlying the talus (Fig. 1). Additionally, the soft tissues about the foot are abnormally shortened and stiff, especially medially and posteriorly [2–4]. The clinical quantification in CTEV is limited by differences among examiners. Traditional radiological evaluation is limited by the lack of tarsal ossification in the young child. US is able to directly image cartilaginous structures and thus can demonstrate the alignment of tarsal structures. Given this, US could have the potential to help quantitate the anatomic abnormalities of clubfeet, much as the Graf and Harcke methods have done for hip dysplasia. Like the sonographic hip examination, dynamic imaging might provide additional useful clinical information.
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Fig. 1 Diagrams and oblique medial coronal US images comparing the normal foot and clubfoot. a Diagram of normal midfoot and hindfoot structures, with the talus and navicular shaded (modified from reference [25]). b Oblique medial coronal sonogram of the normal midfoot with the body of the talus (T) clearly visualized with adjacent proximal cartilaginous medial malleolus (MM) and distal navicular (N). The US cursors mark the points between which the MMN distance is measured. c Diagram of the clubfoot (arrow plantar and medial rotation of the navicular) (modified from reference [25]). d Oblique medial coronal sonogram of the CTEV midfoot demonstrates the medial malleolus (MM) and the proximally subluxed navicular (N) overlying the body of the talus (T) with a shortened MMN distance as compared to the normal foot
While many sonographic measurements have been used in evaluating clubfeet, the primary aim of this study was the development of a standardized dynamic sonographic examination technique primarily focused on the medial tarsal and soft-tissue anatomy of clubfeet. A secondary focus was evaluation of the lateral calcaneocuboid relationships during dynamic maneuvers. The examination was designed to answer specific surgical questions related to the flexibility of the medial foot structures, principally the talonavicular relationship. We chose to use the medial malleolar-to-navicular (MMN) distance as it is a reliable and reproducible measurement of the flexibility of the medial complex of the clubfoot [5–7].
Materials and methods Children referred to orthopedic surgery at our hospital for the evaluation of unilateral or bilateral clubfeet were eligible for inclusion in the study, which was approved by our institutional review board. After clinical evaluation, patients were scheduled for US examination of the feet.
Patients with neurological disorders (cerebral palsy, myelomeningocele), hip dysplasia, and previous foot surgery were excluded. There was no selection or exclusion based upon the clinical assessment of clubfoot severity. Normal control children were recruited from among infants undergoing US examinations for other reasons. Written informed consent was obtained from all of the children’s caregivers. Examinations were performed by one of three experienced pediatric sonologists, using a Sequoia 512 system (Siemens Medical Solutions, Mountain View, Calif.) with a high-frequency linear array probe with a 26-mm footprint operating at 8–15 MHz (depending on patient size and image quality). The US examination was performed as a bimanual examination by one operator. Cine loops were occasionally helpful in uncooperative patients, and a foot pedal was used (and is essential) for image capture. Image display during the examination was the same for both feet in the oblique medial coronal planes (proximal to the left, distal to the right), and with consistent anatomic (left/right) relationships in the transverse plane. The examination was designed to evaluate the foot in four planes: oblique medial coronal, dorsal longitudinal,
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Fig. 2 Dynamic oblique medial coronal views. a Diagrammatic depiction of the oblique medial coronal view performed in the neutral position. The dark line represents the transducer face applied to the medial aspect of the midfoot. b Patient photograph of the oblique medial coronal view performed in the neutral position. c Diagrammatic depiction of the oblique medial coronal view in abduction. d Patient photograph of the oblique medial coronal view performed in abduction
dorsal transverse, and lateral coronal. The images acquired for quantitative analysis of tightness or restriction of the medial complex were oblique medial coronal views from the medial malleolus across the talus to the medial tubercle of the navicular, and were obtained with the foot in the neutral position, in maximal adduction, and then in maximal abduction using a simulated Ponseti maneuver (Fig. 2). Care was taken not to introduce any artificial dorsiflexion or plantar flexion, which can occur when performing the Ponseti maneuver with one hand. Measurements were made from the cartilaginous surface of the Fig. 3 Clubfoot ligamentous gristle. a Diagrammatic representation of ligamentous gristle with both tibiotalar and tibionavicular components. b Medial oblique coronal sonogram demonstrates the gristle (arrow) extending from the medial malleolus (MM) to the navicular (N)
medial malleolus to the medial navicular (MMN distance) in all three positions. In the oblique medial coronal view, the degree of medial navicular–talar subluxation was assessed, and recorded as a percentage of the body of the subluxated navicular bone. Images for qualitative assessment included morphologic evaluation of the navicular bone and calcaneocuboid joint. Lateral coronal images of the calcaneocuboid joint were coronal images obtained in the neutral position, in maximum abduction, and in adduction. Dorsal longitudinal and transverse images of the navicular were obtained at the talonavicular joint.
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Table 1 MMN distances in normal feet and clubfeet Position
MMN distance (mm) Normal feet
Neutral Abduction Adduction
Clubfeet
Mean
SD
Mean
SD
8.78 11.90 6.19
2.40 2.63 2.35
3.47 5.39 1.85
2.19 2.82 1.90
and the log (base 10) of age in days (SAS version 9.1; SAS, Cary, N.C.). Children were divided into three groups (normal feet, normal feet of children with a unilateral clubfoot, and abnormal feet of children with a unilateral clubfoot). Least square means adjusted for the average log(age) were calculated along with standard errors. Multiple comparison P values were adjusted by the Tukey procedure.
Results Enrolled in this initial feasibility study were 24 children (48 feet). There were 14 boys and 10 girls, with a mean age of 14 weeks (range 1–30 weeks). The 24 children included 13 with a unilateral clubfoot deformity and 11 age-matched children with bilateral normal feet. As radiography is not routinely performed, we were unable to compare sonographic results with radiographic findings. Statistical analysis was performed with a mixed model analysis of covariance that adjusted for foot measurements
Morphologic evaluation of the medial complex (including the medial malleolus and the medial aspects of the talus and navicular) in the oblique medial coronal view demonstrated separation of the medial malleolus and navicular in normal feet so that there was no medial covering of the talar body by the medial malleolus (Fig. 1). In contrast, clubfeet demonstrated medial coverage of the proximal and midtalar body by the medial malleolus and to a lesser degree distally by the medially subluxated navicular (Fig. 1). Furthermore,
Fig. 4 Dorsal transverse navicular sonography. a Diagram of the transducer alignment for identification of the talar head. b Diagram of the second step in this procedure, moving the transducer from the talus to the navicular from a dorsal transverse position. c Patient photograph demonstrates the dorsal transverse navicular view. d Dorsal transverse
navicular sonogram demonstrates the medially tapered navicular dysmorphism and navicular subluxation from the talus in a medial and plantar direction (direction of arrow). e Dorsal transverse sonogram of the normal navicular (between arrows) demonstrates the normal cuboid appearance of the navicular. N = navicular
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5 of the 13 clubfeet (38%) demonstrated a clearly thickened medial band of tissue (referred to as “gristle”) with a single point of origin at the medial malleolus, inserting predominantly onto the navicular, and a thinner slip inserting onto the talus (Fig. 3). The mean thickness of this band of gristle was 2 mm (range 1–3 mm). Quantitative data were obtained in the dynamic medial oblique views in all of the 48 feet (100%) and are listed in Table 1. In summary, the MMN distances in all three planes of the dynamic examination were significantly different (P< 0.001) between clubfeet and normal feet (Table 1). The most clinically relevant distances were MMN in the neutral position and abduction. The mean MMN in clubfeet and normal feet, respectively, in the neutral position were 3.47 mm and 8.78 mm, and in abduction were 5.39 mm and 11.90 mm. The mean differences in the MMN distances between unilateral clubfeet and the contralateral normal feet were 6.76 mm in the neutral position and 7.96 mm in abduction (P
