You are in: eMedicine Specialties > Radiology > PEDIATRICS ClubfootArticle Last Updated: Mar 11, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Ellen M Chung, MD, Chief, Pediatric Radiology Section, Department of Radiologic Pathology, Armed Forces Institute of Pathology Ellen M Chung is a member of the following medical societies: American Association for Women Radiologists, American College of Radiology, American Medical Association, American Roentgen Ray Society, Radiological Society of North America, and Society for Pediatric Radiology Coauthor(s): Veronica Rooks, MD, Military Chief of Pediatric Radiology, Pediatric Radiologist, Tripler Army Medical Center; Assistant Professor of Radiology and Radiological Sciences, Uniformed Services University of the Health Sciences Editors: Henrique M Lederman, MD, PhD, Consulting Staff, Department of Radiology, The Children's Hospital of Philadelphia; Professor of Radiology and Pediatric Radiology, Chief, Division of Diagnostic Imaging in Pediatrics, Federal University of Sao Paulo, Brazil; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Kieran McHugh, MBBCh, Honorary Lecturer, The Institute of Child Health; Consultant Pediatric Radiologist, Department of Radiology, Great Ormond Street Hospital for Children, London, UK; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; John Karani, MBBS, FRCR, Consulting Staff, Department of Radiology, King's College Hospital, London Author and Editor Disclosure Synonyms and related keywords: talipes equinovarus, hindfoot equinus, hindfoot varus, forefoot varus, myelomeningocele, arthrogryposis multiplex congenita, tibial hemimelia INTRODUCTIONSection 2 of 12
  BackgroundClubfoot, or talipes equinovarus, is a congenital deformity consisting of hindfoot equinus, hindfoot varus, and forefoot varus. The deformity was described as early as the time of Hippocrates. The term talipes is derived from a contraction of the Latin words for ankle, talus, and foot, pes. The term refers to the gait of severely affected patients, who walked on their ankles.1, 2 PathophysiologyThis deformity is associated with myelomeningocele, arthrogryposis multiplex congenita, and tibial hemimelia. Most cases of congenital talipes equinovarus are idiopathic. The pathophysiology of the more common isolated form is not known and is the subject of controversy. Possible contributing factors include the following: defective cartilage with ligamentous laxity, muscle imbalance, abnormal intrauterine position, central nervous system anomaly, and persistence of a normal fetal relationship. Various theories about the pathophysiology and pathoanatomy focus on primary deformities of the subtalar joint, tibiotalar joint, and talus and on the excessive length of the lateral column relative to that of the medial column. The long-standing controversy regarding the pathophysiology and pathoanatomy has spawned a multitude of varied, sometimes contradictory, surgical approaches. Advances in imaging may someday enhance the understanding of the deformity and help guide surgical treatment. FrequencyUnited StatesClubfoot is common, with an incidence of 1-4 cases per 1000 live births among whites. The risk increases 30-fold in individuals who have a first-degree relative with the condition. Mortality/MorbidityIf untreated or incompletely treated, clubfoot causes an abnormal gait, and stress changes may occur on the lateral (fibular) side of the foot due to preferential weight bearing. SexA slight male predominance may exist, with a male-to-female ratio of 2-3:1. AnatomyTalipes equinovarus mainly consists of hindfoot equinus, hindfoot varus, and forefoot varus (inversion or supination). It is a complex deformity involving many bones, articulations, and soft-tissue structures. Besides the major components mentioned above, other anomalies are present. Muscle shortening is present on the medial side of the foot and leg. The talus is abnormally small, and its dome is less convex than normal. The talar neck is hypoplastic, medially deviated, and plantar flexed so that its articular surface faces medially. The navicular is often subluxed medially. The calcaneus is also small and displaced into a varus, equinus, and internally rotated position. As a result, the calcaneocuboid joint lies beneath, rather than beside, the talonavicular joint. Other aspects of the pathoanatomy are controversial and not well understood. Clinical DetailsClinically, the foot is extremely plantar flexed, with the forefoot swung medially and the sole facing inward. The deformity can be unilateral or bilateral. Preferred ExaminationThe standard radiologic method of evaluation is plain radiography. The equipment required is inexpensive and readily available. Evaluation should include the acquisition of only weight-bearing images because the stress involved is reproducible. In infants, weight bearing can be simulated with the application of dorsal flexion stress. The standard views are the dorsoplantar (DP) and lateral views. For the DP view, the beam is angled 15° toward the heel to prevent overlap of the structures of the lower leg. The lateral view should include the ankle, and not the foot, for proper depiction of the talus. Other methods of imaging are not routinely used in the evaluation of clubfoot, and experience with these is limited.3 Limitations of TechniquesPlain radiography has the disadvantage of exposing the patient to ionizing radiation. Additionally, proper positioning can be difficult. Improper positioning can simulate deformities. Further, because clubfoot is a congenital condition, the lack of ossification in some of the involved bones is another limitation. In neonates, only the talus and calcaneus are ossified. The navicular does not ossify until the child is aged 2-3 years. DIFFERENTIALSSection 3 of 12
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| Measurement | Normal Foot | Clubfoot |
| Tibiocalcaneal angle | 60-90° on lateral view | >90° (hindfoot equinus) on lateral view |
| Talocalcaneal angle | 25-45° on lateral view, 15-40° on DP view | <25° (hindfoot varus) on lateral view, <15° (hindfoot varus) on DP view |
| Metatarsal convergence | Slight on lateral view, slight on DP view | None (forefoot supination) on lateral view, increased (forefoot supination) on DP view |
In an incompletely corrected or recurrent clubfoot, characteristic abnormalities are observed.4 The talocalcaneal angle is normal on the DP view (see Image 8), but talocalcaneal parallelism persists on the lateral view. Flattening of the talar dome persists on this view as well (see Image 9). Cavus of the plantar arch may be present, particularly if no plantar release was performed. Also, a periosteal reaction, sclerosis, or fracture of the lateral metatarsals may occur as a result of abnormal weight bearing on this side of the foot in cases of inadequate correction of forefoot varus (see Images 10-11).
Tarraf and Carroll found that residual forefoot adduction and supination were, by far, the most common deformities that lead to repeat surgery for clubfoot. In addition to hindfoot alignment, these deformities should be actively evaluated on intraoperative radiographs.5
With proper positioning and exposure, quantification of alignment abnormalities on plain radiographs is reliable. No confirmatory imaging is routinely used.
Oblique positioning of the heel on the DP view can simulate hindfoot varus. If the lateral view is one of the foot rather than the ankle, the flat talar dome has a spurious appearance.
Few articles about the use of CT in the elevation of clubfoot have been published. Disadvantages of CT include the risk of ionizing radiation, the lack of ossification of the tarsal bones, susceptibility of the images to motion artifact, and the need for expensive equipment and software applications for multiplanar reconstruction. On the other hand, this complex 3-dimensional deformity may be better assessed in the future with 3-dimensional reconstructions than with 2-dimensional radiographs. The utility of CT in the evaluation of talar articulations in trauma and tarsal coalition is already well established.
In preliminary study of CT with 3-dimensional reconstructions, Johnston et al showed that wire-frame surface renderings of the bones in clubfoot can be created and that the axes of inertia can be computed around the center of mass in 3 perpendicular planes for each bone involved.6 These renderings can be manually rotated to elucidate deformities and misalignments that are obscured because of overlap on plain radiographs. The relationship between the hindfoot bones and ankle mortise can be evaluated in this way, because the information from the lower leg does not overlap. Similarly, the vertical axes of the talus and calcaneus can be compared with a reference line perpendicular to the floor in a coronal reconstruction of the heel. This view can be obtained only with CT.
These analyses revealed that, in the normal foot, both the talus and the calcaneus are medially rotated relative to a line perpendicular to the mortise in the transverse plane, but the rotation in the calcaneus is much less. This difference is the normal divergence of the long axes of the 2 bones. In the clubfoot, the talus is laterally rotated, and the calcaneus is more medially rotated than normal; these rotations cause convergence of the long axes.
Additionally, the authors observed mild pronation of the talus and calcaneus in the coronal plane in the clubfoot, in contrast to mild supination of both in the normal foot. These findings imply that surgical correction should involve supination and medial rotation of the talus in the mortise and supination and lateral rotation of the calcaneus.
MRI is not currently used to image clubfoot, and limited experiences are published in the literature. The use of MRI is limited because of its multiple disadvantages, including the need for equipment and patient sedation, the software-related expenses, the loss of signal caused by the ferromagnetic effects of fixation devices, and the additional time required for data transfer and postprocessing. On the other hand, the advantages of MRI compared with plain radiography and CT are its multiplanar imaging capability and its excellent depiction of ossific nuclei, cartilaginous anlage, and surrounding soft-tissue structures.
Results of a pilot study of MRI and of preliminary work in magnetic resonance multiplanar reconstructions have shown that these methods can be used to elucidate the complex pathoanatomy of this disorder. Intermediate- and T2-weighted spin-echo images are most useful for depicting the cartilaginous anlage and the articular surfaces, respectively.7 When 3-dimensional gradient-echo acquisitions are used to create multiplanar reconstructions, the center of mass and the principle axes of inertia of each bone or cartilaginous structure can be determined. These axes can be compared with each other or a standard of reference to obtain reproducible, objective measurements of the deformities.8
The talar deformity, which many researchers believe is primary in clubfoot, is not precisely defined by using any other imaging modality. However, with the method described above, MRI with multiplanar reconstructions can depict the intraosseous deformity of the talus defined by the elevated talar body-neck angle.
Particularly well defined is the talonavicular relationship, which is not seen on radiographs obtained in young children because of the lack of ossification in the navicular. In most patients, the navicular is medially dislocated.9
Few studies of the ultrasonographic findings in normal feet or clubfeet have been performed, and the clinical utility of this modality has yet to be established. The main disadvantage of ultrasonography is the inability of the beam to penetrate all of the bones, particularly if a postoperative scar is present. Advantages of ultrasonography include the lack of ionizing radiation, no need for sedation, its ability to depict nonossified portions of bones, and its capacity for dynamic imaging.10
Preliminary studies have shown that reproducible views and objective assessments of some of the interosseus relationships in normal feet and clubfeet can be obtained with ultrasonography. In the future, these may assist in directing surgical and conservative therapies for clubfoot and in assessing the results.11
A 7.5-MHz linear transducer and stand-off pad are used to obtain several reproducible and helpful views. The posterior-sagittal view is obtained with the transducer aligned with the midline sagittal plane and placed on the posterior and upper part of the heel. The anteromedial view is obtained from that position at the junction of the ankle and foot, with the foot plantar flexed. The transducer is aligned along the distal tibia, talus, and navicular. The medial transverse view is transverse to the foot on its medial side. A lateral transverse view of the foot may also be useful. Furthermore, these views can be obtained through a dynamic range of motion.
The Achilles tendon can be measured on the posterior-sagittal view. It is often shortened in clubfoot and spastic deformities. On this view, the distal tibia, talus, and calcaneus are perfectly aligned. The distance between the distal ossified tibia and the superior ossified calcaneus can be measured. With plantar flexion, this distance decreases in the normal foot but not in clubfoot. This view permits evaluation of the talonavicular relationship in the DP plane, which is often persistently abnormal after complete subtalar release.
On the anterior-medial view, the medial malleolus, talus, navicular, and medial cuneiform can be seen (see Image 12). The important and elusive talonavicular relationship can be quantified by measuring the distances or angles. The distance between the medial malleolar epiphysis and the cartilaginous navicular can be measured. With medial displacement of the navicular in clubfoot, this measurement is shorter than in the normal foot (see Images 13-16).
Hamel and Becker introduced an angle to quantify the talonavicular relationship. With medial subluxation of the navicular, the angle is positive rather than negative, as it is in normal feet. These measurements can be used to preoperatively estimate the amount of medial release necessary or to assess the success of conservative manipulation and use of braces and/or casts.12
The lateral transverse view may be used to assess the important calcaneocuboid (lateral column) relationship. Future investigations may show that reproducible quantification of this relationship may be useful in directing surgical release of this joint.
The dynamic imaging that is possible with ultrasonography may complement physical examination in the assessment of the rigidity of the foot. Thus, it may aid in the selection of patients for surgical rather than conservative therapy.13
In summary, ultrasonographic evaluation may be used in the future to determine the necessity, site, and amount of soft tissue release and to evaluate the success of therapy.
Nuclear imaging is not used in the evaluation of clubfoot because its depiction of the anatomic detail is insufficient.
Angiograms can show the abnormal size and distribution of the small vessels in the clubfoot, but these findings are of limited clinical usefulness.
Persistent hindfoot misalignment, pes cavus, overcorrection of forefoot varus, persistent forefoot varus, and stress fractures of the lateral metatarsals may occur in a previously treated clubfoot.14 Hindfoot misalignment is almost always corrected if the patient undergoes surgical repair. Stress fractures are an uncommon complication of inadequately treated feet with persistent forefoot varus, which is the most common indication for repeat surgery.15
| Media file 1: Lateral view in talipes equinovarus demonstrates an abnormally elevated tibiocalcaneal angle. A normal angle is 60-90°. | |
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| Media file 2: Normal lateral view shows the measurement of the talocalcaneal angle. The calcaneal long axis is drawn along the plantar surface. The normal range is 25-45°. Note the normal overlap of the metatarsals on the lateral view. | |
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| Media file 3: Lateral view of clubfoot shows the nearly parallel talus and calcaneus, with a talocalcaneal angle of less than 25°. | |
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| Media file 4: Dorsoplantar projection of a healthy foot shows that the line through the long axis of the talus passes just medial to the base of the first metatarsal. The talocalcaneal angle measurement is shown. The normal range is 15-40°. | |
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| Media file 5: Dorsoplantar views obtained in a patient with unilateral clubfoot show that the talus and calcaneus are more overlapped than in the normal condition. The talocalcaneal angle is 15° or less. Note that the line through the long axis of the talus passes lateral to the first metatarsal due to the varus position of the forefoot. | |
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| Media file 6: Dorsoplantar view of talipes equinovarus shows that the convergence of the bases of the metatarsals is abnormally increased compared with the normal convergence (see Image 2). | |
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| Media file 7: Lateral view of shows the ladderlike configuration of the metatarsals in forefoot varus in clubfoot. | |
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| Media file 8: Image of clubfoot obtained after repair shows restoration of a normal talocalcaneal angle on the dorsoplantar view. The line along the long axis of the talus now passes medial to the first metatarsal; this finding indicates overcorrection of the forefoot varus. | |
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| Media file 9: Postoperative lateral view of a clubfoot shows persistent parallelism of the talus and calcaneus. Note the characteristic flattening of the talar dome on this true lateral view of the ankle. | |
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| Media file 10: Lateral radiographs obtained in a 12-year-old girl after surgical clubfoot repair shows persistent forefoot varus and resultant stress changes (cortical thickening) in the most lateral metatarsals. | |
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| Media file 11: DP radiographs obtained in the same girl as in Image 10 after surgical clubfoot repair shows persistent forefoot varus and resultant stress changes to the lateral metatarsals. | |
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| Media file 12: Clubfoot. Sonogram of the medial aspect of a normal foot illustrates the relationships between the cartilaginous medial malleolus (M), ossified talus (T), and nonossified navicular (N). The first metatarsal (1) is also ossified. | |
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| Media file 13: The distance between the medial malleolus (M) and navicular (N) can be reproducibly measured in a dynamic range of motion. Here, it is shown in the neutral position in the normal foot. | |
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| Media file 14: With abduction of the normal foot, the distance between the medial malleolus and the navicular increases. | |
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| Media file 15: Medial ultrasonogram shows a clubfoot in the neutral position. | |
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| Media file 16: Image of a clubfoot in abduction shows a smaller increase in the distance between the medial malleolus and navicular, compared with the distance in the normal foot. This patient may benefit from medial soft tissue release. | |
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Article Last Updated: Mar 11, 2008
