Three-dimensional analysis of clubfoot deformity by computed tomography

Outcome of Atypical & Complex Clubfoot Managed by Modified Ponseti Method-A Prospective Study

Atypical or complex clubfoot constitutes a small number of cases. Due to the difference in complexity of anatomy, standard deformity correction by Ponseti is not effective. Hence a modified Ponseti method was advised which focuses on deformity differences for treatment. We conducted a prospective study to analyze the outcome in atypical or complex clubfoot treated with the modified Ponseti method. All the children of age less than 1 year were included in the study with atypical or complex clubfoot. Every case was treated according to the modified Ponseti method and tenotomy. Pirani scores were measured at pretreatment, each visit, before application of a brace, and at the latest follow-up. Statistical analysis of all continuous and categorical variables was done. A total of 30 patients (47 feet) were included in the study. Mean Pirani score improved from 5.69 at presentation to 0.45 at time of brace application and latest follow-up 0.34 (p < .001). Six patients (9 feet) had a relapse which was managed with recasting. The mean Pirani score of relapse was 0.72, which after correction reduced to 0.11 (p = .008). Six patients had cast-related complications which were managed with conservative treatment. With an increase in popularity of the Ponseti method, a greater number of complex clubfoot cases are seen due to inadequate reduction or slippage of cast or improper cast application techniques. All these need to be identified at an early age. This helps in proper treatment and improves the quality of life as well as foot appearance.

Magnetic Resonance Imaging of Clubfoot Treated With the Ponseti Method: A Short-Term Outcome Study

OBJECTIVE

To quantitatively evaluate the effectiveness of the Ponseti method for the correction of clubfoot, we decided to use magnetic resonance imaging (MRI) to evaluate changes in the tarsal bone relationship.

METHODS

This is a retrospective study of fifteen children with clubfeet who were treated with the Ponseti method. MRI studies were obtained using a 3.0T Machine (GE Healthcare, United States). T1-weighted and T2-weighted images were acquired in the standard anatomic sagittal, transverse, and coronal planes. For the measurement, the best slice that clearly demonstrated the anatomy was chosen. Sagittal talocalcaneal angle, sagittal tibiocalcaneal angle, coronal tibiocalcaneal angle, transverse talar neck angle, transverse talonavicular angle, and transverse talocalcaneal angle were measured. The eighteen corrected clubfeet were compared with the twelve unilateral normal feet at clinical and radiological levels using a Pirani scoring system and MRI, respectively.

RESULTS

In total, 15 cases (twelve boys and three girls) with clubfeet were examined by using MRI. Twelve cases had unilateral and three had bilateral involvement (eleven left clubfeet and seven right clubfeet), giving a total of eighteen clubfeet when compared with twelve normal feet. The mean age of patients at examination was 47.7 months (8-96 months). The recovery of the corrected clubfoot in these patients met the goals of Ponseti treatment (functional, normal looking, pain-free, and plantigrade foot). Before Ponseti treatment, the mean Pirani score of clubfoot was 5.5 (5-6). During this follow-up, the Pirani score was 0.07 (0-0.05). The results of the MRI indicated that only the transverse talonavicular angle showed a significant difference between the treated clubfeet and the normal feet (p < 0.001). One case had dorsal talonavicular subluxation in the sagittal plane and had the lateral subluxation of the navicular in the transverse plane, which has never been reported in previous studies.

CONCLUSION

Although the appearance and function of clubfoot were recovered well after the Ponseti method, the results of MRI indicated that the Ponseti method successfully corrected the varus, cavus, and equinus deformities and incompletely corrected the adduction deformity regarding transverse talonavicular angle. At the same time, the Ponseti method may cause dorsal talonavicular subluxation in the sagittal plane and lateral subluxation of the navicular in the transverse plane on MRI.

Congenital Clubfoot - Is the Ponseti Method the Definitive Solution?

Congenital clubfoot is one of the most common deformities at birth. The inadequacy or absence of treatment causes serious limitations for people with this condition. The initial treatment using the Ponseti method ensures functional results superior to other treatment modalities previously proposed. However, recurrences and neglected feet are still a challenge today. An understanding of the pathophysiology of the disease, as well as of the anatomy and local biomechanics and a thorough clinical and radiological evaluation of patients are essential to understanding the limits of the method and choosing the best treatment.

Assessment of the talar deformity and alignment in congenital clubfoot using three-dimensional MRI after Ponseti method

BACKGROUND

Ponseti method have been widely accepted as the initial treatment of congenital idiopathic clubfoot because its excellent primary result. On the other hand, relapses after Ponseti method are not uncommon and the cause of relapses have not been fully elucidated. We investigated detailed morphology and alignment of tarsal bones in clubfoot after Ponseti method using three-dimensional MRI analysis.

METHODS

We performed MRI with 10 patients of unilateral clubfoot at three months after Achilles tenotomy. Based on the MRI volume data, we reconstructed three-dimensional bone surface model using the marching cubes method. We evaluated the volume of the talus and navicular bone, medial and planter deviation of the talar head and neck, medial deviation of the navicular bone, and internal rotation angle of the distal tibiofibular joint.

RESULTS

In clubfoot, the volume of talus and navicular bone were significantly smaller compared with the contralateral side. Deviation of the talar head and neck varied from medially to almost the same as that on the contralateral side. The degree of deformity of the talus and alignment of the navicular bone and distal tibiofibular joint showed correlations.

CONCLUSIONS

Patients with the medial deviated talar neck might have the alignment change of navicular bone and distal tibiofibular joint. Deformity of talar neck might to be compensated by talonavicular joint and distal tibiofibular joint through the manipulation of Ponseti method.

Residual Equinus After the Ponseti Method: An MRI-based 3-Dimensional Analysis

BACKGROUND

Residual equinus deformity is present in up to 20% of clubfeet treated by the Ponseti method. These patients may require surgical release to restore dorsiflexion. Despite complete posterior release; persistent intraoperative equinus may be present and suggest concurrent joint incongruity. The purpose of this study was to characterize differences in ankle morphology in toddlers with residual equinus following the Ponseti method.

METHODS

Preoperative magnetic resonance imaging (MRI) data from 10 patients who underwent reconstruction (17 feet; 7 bilateral, 3 unilateral clubfeet) for persistent equinus were compared with 16 age-matched controls. Through reverse engineering software, MRI data were used to generate 3-dimensional (3D) models. Four talus-based measures were performed on both MRI data and 3D models-neck depth, neck angle, width, and length. Models were also used to calculate talus volume and arc of curvature (plafond and talar dome). Standard statistical analyses were performed.

RESULTS

Talus volumes, width, and length were less in clubfeet then in control feet. Although some measures were significant there was no mismatch with the ankle mortise dimensions or arc curvature that could account for any decrease in dorsiflexion. We found that from MRI measures the clubfoot neck depth was 2.3 versus 3.6 mm in controls (P<0.001) and from 3D modeling the clubfoot neck depth was 2.3 and 3.5 mm in controls (P=0.003). With 3D modeling talus clubfoot neck angle was 153.7 versus 140.4 degrees in controls (P=0.01). The clubfoot neck angle obtained from MRI measures were also different yet not significant [126.6 in clubfeet versus 122.5 degrees in controls (P=0.12)].

CONCLUSIONS

In comparison to age-matched feet; we have noted a decrease in talar neck depth and an obtuse talar neck angle in clubfeet treated in the manner of Ponseti. This may result in anterior ankle impingement and be the cause of residual equinus despite posterior release. In these procedures, the surgeon should recognize this possibility when the amount of dorsiflexion is less than expected.

LEVEL OF EVIDENCE

Level III-case control study.

Clinico-sonographical evaluation of idiopathic clubfoot and its correction by Ponseti method - A prospective study

BACKGROUND

Objective evaluation of infant with clubfoot is required as conventional imaging modality is of limited usefulness. Ultrasound shows to be a promising technique for assessing deformity and monitoring of clubfoot correction.

AIM

Study was done to evaluate the deformity sonographically; to assess the changes in these parameters after treatment by Ponseti method and to correlate these ultrasonographic variables with clinical Pirani score.

MATERIALS AND METHODS

82 feet in 54 children were observed. Clinical assessment was done using Pirani six point system and ultrasound machine with 7.5-12MHz linear transducer was used to measure several parameters and data obtained was assessed to derive correlation between sonographic parameters and clinical system.

RESULTS

Medial malleolus navicular distance (MMN) measured on medial view, calcaneo-cuboid distance (CCD) and calcaneo-cuboid angle (CCA) measured on lateral view, talar length (TAL) measured on dorsal view and tibio-calcaneal distance (TCL) measured on posterior view showed statistical significance. Sonographic parameters correlated statistically with Pirani scoring system on measuring Pearson correlation coefficient.

CONCLUSION

Ultrasound is a relatively simple, non invasive and widely available procedure that can improve pathomorphological documentation of nonossified clubfoot and its correction.

LEVEL OF EVIDENCE

Level II prospective study, as per guidelines for authors.

Influence of tibialis posterior muscle activation on foot anatomy under axial loading: A biomechanical CT human cadaveric study

BACKGROUND

Collapse of the medial longitudinal arch and subluxation of the subtalar joint are common occurrences in adult flatfoot deformity. Controversy exists about the role of the tibialis posterior (TP) tendon as first and/or essential lesion. Subtle changes in the foot configuration can occur under weight bearing.

PURPOSE

This human cadaveric study is designed to investigate the effect that isolated actuation of the TP tendon has on the medial longitudinal arch and the hindfoot configuration under simulated weight bearing.

METHODS

A radiolucent frame was developed to apply axial loading on cadaveric lower legs during computer tomography (CT) examinations. Eight pairs of fresh-frozen specimens were imaged in neutral position under foot-flat loading (75N) and under single-leg stance weight bearing (700N) without and with addition of 150N pulling force on the TP tendon. Measurements of subtalar joint subluxation, forefoot arch angle and talo-first metatarsal angle were conducted on each set of CT scans.

RESULTS

Subtalar subluxation, talo-first metatarsal angle and talo-navicular coverage angle significantly increased under single-leg stance weight bearing, whereas forefoot arch angle significantly decreased. Actuation of the TP tendon under weight bearing did not restore the forefoot arch angle or correct subtalar subluxation and talo-metatarsal angle.

CONCLUSION

Significant effect that weight bearing has on the medial longitudinal arch and the subtalar joint configuration is demonstrated in an ex-vivo model. In absence of other medial column derangement, actuation of the TP tendon alone does not seem to reconstitute the integrity of the medial longitudinal arch or correct the hindfoot subluxation under weight bearing.

CLINICAL RELEVANCE

The findings of this study together with the developed model for ex-vivo investigation provide a further insight in foot anatomy.

The influence of the Peroneus Longus muscle on the foot under axial loading: A CT evaluated dynamic cadaveric model study

BACKGROUND

Subtle hypermobility of the first tarsometatarsal joint can occur concomitantly with other pathologies and may be difficult to diagnose. Peroneus Longus muscle might influence stability of this joint. Collapse of the medial longitudinal arch is common in flatfoot deformity and the muscle might also play a role in correcting Meary's angle.

METHODS

A radiolucent frame was used to simulate weightbearing during CT examination. Eight pairs fresh-frozen lower legs were imaged in neutral position under non-weightbearing (75N), weightbearing (700N) and with 15kg weights hung from Peroneus Longus tendon. Measurements included first metatarsal rotation, intermetatarsal angle, first tarsometatarsal joint subluxation and Meary's angle.

FINDINGS

Weightbearing significantly increased Meary's angle and significantly decreased first tarsometatarsal joint subluxation (both P<0.01). Pulling Peroneus Longus tendon significantly increased first metatarsal rotation (P<0.01), significantly decreased the intermetatarsal angle (P<0.01) and increased non-significantly Meary's angle (P=0.52).

INTERPRETATION

A considerable effect weightbearing has on the medial longitudinal arch and first tarsometatarsal joint was observed. Pulling Peroneus Longus tendon improved first metatarsal subluxation but increased its rotation. The study calls into question the importance of this tendon in maintaining the medial longitudinal arch and raises concerns about rotational deformity of the first metatarsal following hallux valgus correction without first tarsometatarsal arthrodesis.

CLINICAL RELEVANCE

Study outcomes will provide more insight in foot pathology.

WHAT IS KNOWN ABOUT THE SUBJECT

Weightbearing affects anatomy of the foot. No reliable information is available concerning the influence of the Peroneus muscle.

WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE

This study investigates the influence of weightbearing and the impact the Peroneus muscle on the anatomy of the foot.

Subtalar joint configuration on weightbearing CT scan

BACKGROUND

Standard values that describe the morphology of the subtalar (ST) joint have previously been obtained from cadaveric studies or by using conventional unloaded radiographs. It is known that these parameters differ significantly from those measured in vivo and in loaded images, limiting the diagnostic value of the previously published morphological parameters in the literature. However, the morphology of the ST joint clearly affects its function. The objective of this study was to determine the morphology of the posterior facet of the ST joint using loaded computed tomography (CT) images and to describe the different configurations found in asymptomatic patients.

METHODS

A weightbearing CT scan was performed on 59 patients without any history of hindfoot and ankle pathology. The shape of the posterior facet and the subtalar vertical angle (SVA) were measured in 3 different coronal planes of the ST joint.

RESULTS

The posterior facet was concave in 88% and flat in 12%. The posterior facet was oriented in valgus in 90% and varus in 10% when measured in the middle coronal plane. However, the SVA changed depending on which coronal plane it was measured in.

CONCLUSION

We believe it is important to get a better insight into the morphological parameters of the ST joint.

CLINICAL RELEVANCE

Knowledge of subtalar joint morphology could help clarify why certain failures have occurred in reconstructive hindfoot surgery and thus might help plan the surgical procedure to reduce these failures in the future.

CT study on the effect of different treatment protocols for clubfoot pathology

In congenital clubfoot, residual deformities are not well-documented and they may change depending on different treatments. To identify the treatment that provides better outcome at maturity, we studied the computed tomography of two cohorts of patients affected with congenital clubfoot who were treated using two distinct protocols. Forty-seven clubfeet were treated according to the traditional protocol of our hospital and 61 were treated according to the Ponseti technique. The normal feet of the unilateral deformities served as controls. All patients were followed to skeletal maturity. The ankle torsion angle and the declination angle of the neck of the talus were higher than normal but different only in patients treated with the traditional method. The calcaneocuboid angle was lower but only in patients treated with the Ponseti method. The shape of the talar joints was altered in many feet regardless of protocol. The CT images suggest the modifications of the torsion angle of the ankle, the declination angle of the neck of the talus, and the calcaneocuboid angle at maturity are related to the treatment protocol followed. The Ponseti manipulative technique provided better anatomical results in comparison to our traditional technique.

Achilles tendon length in children evaluated sonographically

The purpose of this study was to improve our knowledge of the behavior of the Achilles tendon as a basis for decision-making in Achilles lengthening or tenotomy, we sonographically measured the normal and club feet of 101 babies, mean age 4 months, in standard parameters: tibio-talo-calcaneal angle, length of Achilles tendon, distance from tibia to calcaneus, and distance from a line parallel to the posterior cortex of the tibia to the calcaneus. All measurements were age-matched from birth to 1 year in maximal plantar and dorsal flexion. In conclusion, we describe the normal values for the four parameters in plantar and dorsal flexion. These can serve as a basis for decision-making in clubfoot management.

Anatomical study for an update comprehension of clubfoot. Part I: Bones and joints

PURPOSE

The aim of our study was to elucidate the gross anatomical changes of bones and joints in idiopathic clubfeet.

METHODS

Gross dissection was carried out on seven idiopathic clubfeet of fetuses aborted between the 25th and 37th week of gestation and compared to two normal feet (27th and 36th week of gestation). Particular attention was paid to the articular surfaces, shapes and angles of all bones and their skeletal relationships.

RESULTS

The talar neck-trochlea angle in clubfeet ranged from 37 degrees to 41 degrees , in normal feet from 27 degrees to 33 degrees . In clubfeet the deviation of the neck of the talus relative to the body was between 28 degrees and 43 degrees , in normal feet between 22 degrees and 24 degrees . The posterior joint surface was in an anterolateral position and even flat transversely. The head of the clubfeet tali was turned along a longitudinal axis in the opposite direction compared to the normal ones. Instead of a typically saddle-shaped posterior talar surface of the calcaneus, it was triangular and flat transversely, and a bony stability in the subtalar joint was not achieved. The angle of torsion of the calcaneus showed no significant difference between normal and clubfeet. The anterior surface was flat, medially twisted and orientated upwards.

CONCLUSIONS

We presume that the calcaneus is the primary fault, which might be explained by pathologic biomechanical forces during development.

[3D modeling in the field of morphology: methods, interest and results]

The aim of this paper is to show the major role played by the new computerized imaging tools available today in the fields of morphology and anatomy. For anatomical studies or educational purpose, they enhance the classical techniques. The 3D reconstruction, already used in daily clinical practice, will be the basis for computation of validated volumetric protocols enhancing our diagnosis and prognosis means. It is also a fantastic educational tool: the interactivity makes it simple, efficient, attractive and easily accessible and diffusable. For the research, mathematical modeling of embryogenesis and morphogenesis using finite elements method will open new ways for biomecanics and a dynamic quantification approach.

Assessment of the three-dimensional relationship of the ossific nuclei and cartilaginous anlagen in congenital clubfoot by 3-D MRI

PURPOSE

Radiographic measurement is the usual method used to objectively determine the extent of a congenital clubfoot deformity. Although radiographs have been used clinically to estimate the size and location of tarsal bones through measurements of the ossific nuclei, it is not clear to what extent these relationships are actually reflected in these measurements. So, we used a 3-D MRI system that could more objectively estimate sizes and positional relationships.

MATERIAL AND METHOD

We evaluated 5 patients with unilateral congenital clubfoot deformity. Magnetic resonance imaging was performed of both feet using 1.5-T magnet. Based on the resulting magnetic resonance imaging volume data, a three-dimensional surface bone model was reconstructed by the Marching Cubes method. We used this model to perform a comparative analysis of the volume and volume ratio of each cartilaginous anlage and ossific nucleus, the length of the talus and the calcaneus, and the position of the center of gravity of ossific nuclei within the cartilaginous anlagen. We measured the relationship between the ossific nuclei and cartilaginous anlagen in the talus and calcaneus of patients with unilateral clubfoot deformity.

RESULT

In clubfeet talus volume was reduced by 20.1% and calcaneal volume was reduced by 15.7%. Furthermore, the volume of the talar ossific nucleus was reduced by 42.6% and that of the calcaneal ossific nucleus was reduced by 12.1%. The length of the clubfoot talus was 8.2% shorter than normal, and that of the calcaneus was 4.8% shorter.

CONCLUSION

The assessment technique presented herein was shown to be useful in ascertaining the various pathological characteristics associated with clubfoot.

Assessment of talus deformity by three-dimensional MRI in congenital clubfoot

PURPOSE

To evaluate the morphological deformity of talus in congenital clubfoot by three-dimensional MRI.

MATERIAL AND METHOD

Subjects were five patients (two male, three female, mean age 5 months) with unilateral congenital clubfoot. Magnetic resonance imaging was performed of both feet using 1.5 T magnet. Based on the resulting magnetic resonance imaging volume data, a three-dimensional surface bone model was reconstructed by the Marching Cubes method. The long axis of the reconstructed model was determined, and in relation to the standard planes including this axis, the degree of talar head and neck deviation, and the relative positioning of the talus and navicular in the talonavicular joint were compared between normal foot and clubfoot.

RESULT

The talar head and neck angle in relation to the talus exhibited significant medial deviation in the clubfoot, but the degree of plantar deviation of the talar head and neck did not show significance. The navicular was located more medially in clubfoot than in normal foot. The volume of the total talar and of the ossific nucleus for the clubfoot was smaller than that for the normal foot.

CONCLUSION

The assessment technique presented herein was shown to be useful in ascertaining the various pathological characteristics associated with clubfoot.

Sonographic assessment of clubfoot

PURPOSE

This study was performed to develop a standardized methodology for the sonographic assessment of clubfoot at birth and at the end of both conservative treatment and surgical correction.

METHODS

Forty-two congenital clubfeet and 42 normal feet were examined sonographically in the position of spontaneous alignment and during passive manual correction. Scans along 4 planes provided information relevant to the assessment: sagittal posterior, sagittal anterior, coronal lateral, and transverse.

RESULTS

Sagittal posterior sonograms demonstrated the progressive gain of dorsiflexion ability during the different steps of treatment for clubfoot. Sagittal anterior sonograms could not demonstrate the normal alignment of the navicular in clubfeet because of the bone's medial displacement. On transverse sonograms, the talar head and the medially displaced navicular may lie on the same plane, depending on the severity of the deformity. Coronal lateral sonograms provided for estimation of the relationships between the calcaneus and cuboid, which were described by the calcaneal-cuboid angle.

CONCLUSIONS

Sonography is a promising technique for assessment and monitoring of clubfoot during treatment. The method described here yields accurate and reproducible information about the anatomy of the nonossified clubfoot, helping the orthopedic team decide on appropriate treatment steps.

Magnetic resonance imaging in follow-up of treated clubfoot during childhood

In this study, we evaluated the short-term results of surgically treated clubfoot with magnetic resonance imaging (MRI). T1- and T2-weighted MRI images with 4-mm slices in the standard anatomic sagittal, transverse, and coronal planes were obtained in seven cases of clubfoot aged 4--11 years (mean 5.6 years old). The mean follow-up period was 3.6 years (ranged between 2 and 6 years). Sagittal talocalcaneal angle, talar head and neck axis internal rotation, calcaneal axis internal rotation, transverse talar neck and head/calcaneus angle and posterior calcaneus external rotation were measured. Three cases with dorsal talonavicular subluxation and a case of calcaneocuboid luxation were demonstrated by MRI. It was concluded that MRI may help to understand results of surgically-treated clubfoot by revealing hindfoot articular relationships and many complications.