Tarsal navicular relations in club foot: is there a role for magnetic resonance imaging?

Correlation of radiographic parameters with clinical correction in idiopathic congenital talipes equinovarus undergoing Ponseti treatment

PURPOSE

Idiopathic congenital talipes equinovarus is the most commonly encountered congenital deformity of the foot. Ponseti technique of manipulation is the treatment of choice. The Pirani classification is a reliable scoring system for clinical evaluation of clubfeet. The role of radiographic parameters in the evaluation and treatment of clubfeet is still controversial. The aim of this study was to evaluate the correlation of radiological parameters with clinical correction in patients with idiopathic clubfeet undergoing correction using Ponseti method.

METHODS

Between March 2018 and March 2019, 42 feet in 27 patients with idiopathic clubfeet were treated in our hospital. We used the Pirani scoring system for clinical evaluation. Anteroposterior and lateral views of the feet were taken before and after correction and at the last follow-up. The anteroposterior view was evaluated for the talocalcaneal angle and talo-first metatarsal angle, while the lateral view was only evaluated for the talocalcaneal angle.

RESULTS

Twelve were boys (44.4%), and 15 were girls (55.6%). The deformity was bilateral in 15 patients (55.6%) and unilateral in 12 patients (44.4%). The average age was three months. According to the Pirani score, the mean Pirani Total score was 4.4 before correction and reduced to 0.4 after correction. The mean talocalcaneal angle in anteroposterior and lateral views was 15.1° and 7.8° before correction, increased to 32.7° and 31.8° after correction, respectively. The mean talocalcaneal index increased from 23.2 before correction to 64.5 after correction. The mean talo-first metatarsal angle in anteroposterior view improved from 25.7° before correction to - 1.6° after correction. The relation between the differences in Pirani scores before and after correction and the differences in measured radiographic parameters before and after correction revealed a statistically significant correlation.

CONCLUSION

Radiographic parameters showed a statistically significant correlation with the clinical outcome. Thus, evaluation of clubfeet correction treated by Ponseti technique can rely mainly on clinical scores with limited utilization of radiological assessment.

3D MRI analysis of the lower legs of treated idiopathic congenital talipes equinovarus (clubfoot)

Background

Idiopathic congenital talipes equinovarus (CTEV) is the commonest form of clubfoot. Its exact cause is unknown, although it is related to limb development. The aim of this study was to quantify the anatomy of the muscle, subcutaneous fat, tibia, fibula and arteries in the lower legs of teenagers and young adults with CTEV using 3D magnetic resonance imaging (MRI), and thus to investigate the anatomical differences between CTEV participants and controls.

Methodology/Principal Findings

The lower legs of six CTEV (2 bilateral, 4 unilateral) and five control young adults (age 12–28) were imaged using a 3T MRI Philips scanner. 5 of the CTEV participants had undergone soft-tissue and capsular release surgery. 3D T1-weighted and 3D magnetic resonance angiography (MRA) images were acquired. Segmentation software was used for volumetric, anatomical and image analysis. Kolmogorov-Smirnov tests were performed. The volumes of the lower affected leg, muscle, tibia and fibula in unilateral CTEV participants were consistently smaller compared to their contralateral unaffected leg, this was most pronounced in muscle. The proportion of muscle in affected CTEV legs was significantly reduced compared with control and unaffected CTEV legs, whilst proportion of muscular fat increased. No spatial abnormalities in the location or branching of arteries were detected, but hypoplastic anomalies were observed.

Conclusions/Significance

Combining 3D MRI and MRA is effective for quantitatively characterizing CTEV anatomy. Reduction in leg muscle volume appears to be a sensitive marker. Since 5/6 CTEV cases had soft-tissue surgery, further work is required to confirm that the treatment did not affect the MRI features observed. We propose that the proportion of muscle and intra-muscular fat within the lower leg could provide a valuable addition to current clinical CTEV classification. These measures could be useful for clinical care and guiding treatment pathways, as well as treatment research and clinical audit.

Ultrasound assessment of early clubfoot treatment: a comparison of the Ponseti method and a modified Copenhagen method

The purpose of this study was to sonographically compare the early anatomical outcome of a group of clubfeet treated with the Ponseti method (group A, nine clubfeet) with a group treated with an adjustable plexidur splint, the Copenhagen method (group B, 19 feet). The clinical severity was assessed using the Diméglio-Bensahel classification. The need for complementary surgery was clinically assessed at the age of about 2 months. Ultrasound investigation was made in the neonatal period, after 2-3 months of non-surgical treatment and 1-2 months post-surgically. After 2 months of non-surgical treatment the correction obtained at the talo-navicular joint, expressed as the distance between the medial malleolus and the navicular (MM-N distance), was significantly greater in group A. After surgery, tenotomy of the Achilles tendon for all group A feet, and posterior or posteriomedial release for 13 feet in group B, the correction at the talo-navicular and calcaneo-cuboid joints was similar for the two groups. Anatomical correction of the displacement in these joints can be achieved without extensive interventional procedures. Ultrasound may be a valuable tool to assess the effects of different treatment protocols quantitatively.

Magnetic resonance imaging study of the congenital clubfoot treated with the Ponseti method

Little information exists about the degree of efficacy of the several nonoperative treatments, such as manipulation and casting, used in correcting the pathology of the virgin clubfoot deformity. The steps in the correction of the displacements and anomalies of the skeletal components have never been visualized. The method reported to have the best long-term results is that of Ponseti. A magnetic resonance imaging protocol was devised to image the described chondroosseous abnormalities of the virgin clubfoot deformity and to illustrate the changes that occur with the Ponseti method of treatment. Scans were performed at the beginning of, in the middle of, and at the end of treatment. Images obtained with this protocol largely agree with postmortem studies of clubfeet. All of the major chondroosseous pathology could be visualized in vivo. With Ponseti treatment, all the abnormalities seen on the initial scans either improved markedly or corrected completely. Treatment resulted in correction not only of the abnormal relationships of the tarsal bones, but also of the abnormal shapes of the individual tarsal osteochondral anlages, probably because of the changes in growth resulting from the changes in mechanical loading of fast-growing tissues.

MR evaluation of talonavicular angle in congenital talipes equinovarus

The talonavicular relationship in 14 patients with talipes equinovarus was quantified using gradient echo sequences. The angle formed between the short axis of the navicular and the long axis of the talus was measured. There is a significant difference in the talonavicular angle between patients who had posteromedial release (PMR) and those who had posterior release (PR) or casting only (P=.0004). This method provides an objective assessment of residual deformity following surgical and conservative management of talipes equinovarus.