Foot deformities in diastrophic dysplasia. An analysis of 102 patients

Identification of potential non-invasive biomarkers in diastrophic dysplasia

Diastrophic dysplasia (DTD) is a recessive chondrodysplasia caused by pathogenic variants in the SLC26A2 gene encoding for a cell membrane sulfate/chloride antiporter crucial for sulfate uptake and glycosaminoglycan (GAG) sulfation. Research on a DTD animal model has suggested possible pharmacological treatment approaches. In view of future clinical trials, the identification of non-invasive biomarkers is crucial to assess the efficacy of treatments. Urinary GAG composition has been analyzed in several metabolic disorders including mucopolysaccharidoses. Moreover, the N-terminal fragment of collagen X, known as collagen X marker (CXM), is considered a real-time marker of endochondral ossification and growth velocity and was studied in individuals with achondroplasia and osteogenesis imperfecta. In this work, urinary GAG sulfation and blood CXM levels were investigated as potential biomarkers for individuals affected by DTD. Chondroitin sulfate disaccharide analysis was performed on GAGs isolated from urine by HPLC after GAG digestion with chondroitinase ABC and ACII, while CXM was assessed in dried blood spots. Results from DTD patients were compared with an age-matched control population. Undersulfation of urinary GAGs was observed in DTD patients with some relationship to the clinical severity and underlying SLC26A2 variants. Lower than normal CXM levels were observed in most patients, even if the marker did not show a clear pattern in our small patient cohort because CXM values are highly dependent on age, gender and growth velocity. In summary, both non-invasive biomarkers are promising assays targeting various aspects of the disorder including overall metabolism of sulfated GAGs and endochondral ossification.

Gait Pattern and Lower Extremity Alignment in Children With Diastrophic Dysplasia

BACKGROUND

The aim of this study was to describe the dynamic lower extremity alignment in children with diastrophic dysplasia (DD) by 3-dimensional gait analyses. Our main hypothesis was that gait kinematics and kinetics are different than the age-normalized population and patellar dislocation can alter the gait in patients with DD.

METHODS

A retrospective review of clinical data and radiographs was conducted for patients with DD who had gait analysis before lower extremity skeletal surgery excluding foot procedures. Lower extremity range of motion was measured. The Pediatric Outcomes Data Collection Instrument (PODCI) was administered to parents to evaluate their children's functional status. Gait laboratory data were collected to compare the hip and knee kinematics in cases with and without patellar dislocation. Anteroposterior standing radiographs were taken for all patients to assess the correlation between measurements (clinical, radiologic, and gait) for coronal knee alignment.

RESULTS

Thirty lower extremities of 15 children (7 females and 8 males) were evaluated. The mean age was 7.4±3 years, the mean height was 97.7±15 cm (z=-5.1), and the mean weight was 20.6±6.2 kg (z=-0.8). The DD PODCI subscores were statistically significantly lower (P<0.05) than the average stature for developing children, except for the happiness score. Gait analysis, compared between all DD and an age-normalized average stature group, showed decreased forward velocity, step length, and stride length with an increased average forward tilt of the trunk and pelvis, hip flexion, hip adduction, and internal rotation (P<0.001). Delta hip and knee motion were also decreased (P<0.001). The patella was dislocated in 19 (63.3%) and central in 11 (36.6%) knees. Comparison of the minimum knee and hip flexion at the stance phase demonstrated increased crouch gait in the patellar dislocation group (P<0.001). Knee alignment measurements between clinical examination and gait analysis showed moderate correlation (r, 0.476; P=0.008).

CONCLUSIONS

Children with DD demonstrated lower PODCI subscores except for happiness. Gait analysis showed limited lower extremity function of the children with DD in our study group. Patella dislocation group had increased crouch gait.

LEVELS OF EVIDENCE

Level III-diagnostic study.

Health-related quality of life in patients with diastrophic dysplasia

Diastrophic dysplasia (DD), a congenital skeletal dysplasia, is characterized by short, disproportionate stature, multiple severe spinal and joint deformities, and normal mental status. The health-related quality of life (HRQOL) of patients with DD was measured by a standardized fifteen-dimensional (15D) method, that includes a questionnaire and a valuation task. Eighteen patients (5 males and 13 females) with a mean age of 23 years (range 17 - 31 years), representing half of the Finnish patients with DD in this age group, completed the questionnaire and the valuation task. The data obtained were compared with those of 273 age- and sex-matched controls. A 15D profile was drawn, and the average importance weight of each dimension and the average within-dimension level values were calculated for both groups. The average 15D score, describing the overall HRQOL, was derived for both groups using the valuations of each group. The health profiles of the groups differed significantly in several dimensions. When the health levels within the dimensions were concerned, the controls rated all values deviating from ``normal'' lower than did the patients. The average 15D scores of the patients with DD were significantly lower than those of the controls. The 15D scores were higher in both groups when the valuations of the patients with DD were used. The study showed that, although the overall HRQOL of the patients with DD was inferior to that of the controls, the patients showed greater adaptability to deviations in health status than did the controls.

Corrections of lower limb deformities in patients with diastrophic dysplasia

OBJECTIVE

Accurate understanding of the cause of the underlying pathology in children with diastrophic dysplasia would help in designing targeted management of their locomotion.

METHODS

Diastrophic dysplasia was diagnosed in twelve patients (nine girls and three boys; age range 1-14 years), all of whom presented with small stature and apparent short extremities. Club foot (mostly talipes equinovarus) was the most frequent and consistent abnormality. Concomitant abnormalities such as hip flexion contracture, flexion contractures of the knees with excessive valgus deformity and lateral patellar subluxation, were also encountered. Muscle ultrasound and muscle magnetic resonance imaging imaging showed no myopathic changes and muscle biopsies and the respiratory chain were normal. Serum choline kinase and plasma lactate concentrations were normal.

RESULTS

Surgical correction of the foot and ankle in patients with diastrophic dysplasia is extremely difficult because of the markedly distorted anatomy. In all of these children, plantigrade foot was achieved along with the improved function of the locomotor system. Mutations of the diastrophic dysplasia sulfate transporter (also known as solute carrier family 26 member 2) were encountered.

CONCLUSION

Arthrogryposis multiplex is the usual terminology used to describe the abnormality in infants with multiple contractures. Diligent orthopaedic care should be provided based on an accurate understanding of the associated syndromes in such children.

Recurrent ankle equinus deformity due to intramuscular hemangioma of the gastrocnemius: case report

Level of Evidence: V, Expert Opinion

Autosomal recessive multiple epiphyseal dysplasia in a Korean girl caused by novel compound heterozygous mutations in the DTDST (SLC26A2) gene

Multiple epiphyseal dysplasia is caused by heterogeneous genotypes involving more than six genes. Recessive mutations in the DTDST gene cause a phenotype of recessive multiple epiphyseal dysplasia (rMED). The authors report a 9-yr old Korean girl with the rMED phenotype having novel compound heterozygous mutations in the DTDST gene, which were inherited from both parents. This is the first Korean rMED case attributed to DTDST mutations, and expands the spectrum of diseases caused by DTDST mutations.

Pediatric metatarsus adductus and skewfoot deformity

Skewfoot is a rare condition that is often missed early in a child's development. Mild and flexible forms can be successfully treated with cast immobilization and shoe therapy. In more severe forms, surgical intervention is indicated if there are underlying neuromuscular conditions or the individual is affected on a daily basis because of the deformity. Careful evaluation and proper surgical procedures selection can realign the foot, resulting in favorable long-term outcomes. This article presents clinical and radiographic evaluation techniques and treatment options.

Skewfoot

Skewfoot is a rare deformity characterized by forefoot adduction and hindfoot valgus. Its etiology and natural history are unknown, although congenital and syndromic forms are observed. Currently, there is no consent about the treatment of skewfoot. Due to its potential resistance to the effects of therapy, it must be differentiated from other, more common deformities. Treatment involves conservative and, most often, operative measures.

Fetal MR imaging of atelosteogenesis type II (AO-II)

The diastrophic dysplasia family of osteochondrodysplasias comprises a spectrum of skeletal diseases characterized by abnormal growth and remodelling of cartilage and bone. They are caused by mutations in the diastrophic dysplasia sulfate transporter (DTDST) gene. Different defects in this gene product give rise to the variety of phenotypes based on the level of residual transport capacity. We reported a case of a fetus with this spectrum, evaluated and diagnosed with fetal MRI.

The 3-dimensional configuration of the typical foot and ankle in diastrophic dysplasia

BACKGROUND

Surgical correction of the foot and ankle in patients with diastrophic dysplasia is extremely difficult secondary to the markedly distorted pathoanatomy. Several authors have described superficially some of the clinical and radiographic findings typical of the foot and ankle with diastrophic dysplasia; however, no description of the specific osseous deformities has been described in the literature. The purpose of this article was to provide such a model, detailing the nature of deformity of each of the bones and joints in the foot and ankle and their relationship to each other from a pathoanatomical standpoint.

METHODS

A 3-dimensional sculpted model and detailed drawings were developed based on radiographs, computed tomography reconstructions, and direct observation both in and out of surgery. Fifty-three patients representing 106 feet formed the basis of this analysis (age, 3 days to 32 years). An additional 12 feet of the senior author's cases provided further confirmation of these deformities.

RESULTS

Superficially, the apparent deformity most closely resembles a Z-type foot or serpentine foot. The overall deformity bears no true resemblance to the idiopathic clubfoot. Typically, the hindfoot is in severe equinus with the subtalar joint being deformed into valgus and moving more posteriorly. In contrast to the idiopathic clubfoot, the navicular was markedly angulated laterally on the talus. The medial cuneiform was deviated medially on the navicular articulation. The forefoot was foreshortened and in marked varus positioning with varus of the entire metatarsals. The second to fifth metatarsals bend and curve near their bases as they tilt toward the first metatarsal.

CONCLUSION

The disturbed pathoanatomy of the diastrophic dysplasia foot and ankle reflects the difficulties in achieving any substantial surgical correction without customization. Surgical management of the foot and ankle in diastrophic dysplasia must be individualized and based on a clear understanding of the unique segmental malalignment of the foot and ankle.

Walking ability in patients with diastrophic dysplasia: a clinical, electroneurophysiological, treadmill, and MRI analysis

Patients with diastrophic dysplasia have walking difficulties of obscure etiology; some are even wheelchair-bound. To explore the problem, physical examination, treadmill, magnetic resonance imaging (MRI), and electroneurophysiologic studies were performed on 87 patients (56 females, 31 males) with an average age of 31 (range 3-56) years. Mobility of the spine, hips, knees, and feet was diminished. Some of the patients were obese (mean body mass index 27.0 kg/m). In the treadmill study, patients were able to walk an average of 638 m (range 0-1,618 m). On MRI, five patients showed compression of neural structures; one of them also had clinical symptoms. Somatosensory evoked potentials and electroneuromyography revealed evidence of compression of neural structure in three (3%) and two (3%) patients, respectively. The walking difficulties seem to have a multifactorial etiology: flexion contractures of the knees, early and rapid osteoarthrosis, equinus or equinovarus foot deformities, and obesity, but only rarely spinal stenosis.

Lung function in diastrophic dysplasia

Diastrophic dysplasia (DD) is a rare skeletal dysplasia characterized by short-limbed short stature, contractures and early degeneration of joints, and spinal deformities such as scoliosis. Mortality is increased in the neonatal period, in part due to tracheo- and bronchomalacia. Additionally, spinal deformities are very rigid, decreasing mobility of the chest cage. The aim of our study was to evaluate lung volumes and airway flow dynamics in patients with DD. A total of 31 patients (12 males, 19 females) underwent a detailed clinical examination measurements of standing height PA-radiography of the spine, flow-volume spirometry, and body plethysmography. The patients were assigned to two groups: children and adolescents (0-18 years, n = 18) and adults (over 18 years, n = 13). The mean spirometric parameters were mostly within the predicted value range, although the variation was wide. At least one abnormally low spirometry parameter was found in 6 (33%) of the children and adolescents and in 7 (54%) of the adults. Mean forced vital capacity (FVC) was 104% (range 48-163%) of predicted values in the children and adolescents and 95% (58-140%) of the adults. Peak expiratory flow (PEF) values were abnormal in 4 (22%) of the children and adolescents and in 5 (39%) adults. The mean plethysmographic parameters were all within the predicted value range. At least one abnormal plethysmographic value was found in 6 (33%) of the children and adolescents and in 4 (31%) of the adults. Airway resistance (Raw) was significantly higher in the adults than in the children and adolescents (P = 0.016), and was abnormally high in 3 (23%) of the adults. The angle of thoracic or thoracolumbar scoliosis correlated with the percentages of the predicted values of FVC (r(s) = - 0.66), forced expired volume in 1 sec (FEV(1)) (r(s) = - 0.56), and total lung capacity (TLC) (r(s) = - 0.67). Age correlated with the FEV(1)/FVC ratio (r(s) = - 0.41), with the maximal expired flow at 50% FEV (MEF(50)) values (r(s) = - 0.55), with the residual volume (RV) values (r(s) = - 0.47), and with the RV/TLC ratio (r(s) = - 0.43). Variable bronchial obstruction was found in 1 (6%) child and in 2 (17%) adults. Although the patients with DD had, on average, normal lung volumes, large individual variation occurred. Airway resistance was increased in adults. The angle of scoliosis correlated inversely with lung volume parameters.

Perceptions of the outcome of orthopedic surgery in patients with chondrodysplasias

As part of a larger survey of patients with chondrodysplasias, 197 patients or their parents were asked whether they had undergone orthopedic surgery related to their chondrodysplasia and, if so, to rate their impression of the outcome. Seventy-four patients (37.6%) had undergone a total of 152 procedures (221 if concurrent bilateral operations are counted separately). The percentage of patients treated surgically ranged from a low of 8.3% for hypochondroplasia to a high of 87.5% for diastrophic dysplasia. Of the patients who had surgery, the mean number of procedures per patient ranged from 1.0 for hypochondroplasia to 2.69 for pseudoachondroplasia. Of 180 individual procedures related to the limbs, the outcome in 88.8% was judged 'a bit better' or higher and in 68.8% 'much better' or higher. The responses ranged from a low of 70.4 and 66.7%, respectively for proximal femoral osteotomies to a high of 100 and 85.9% for hip replacement. The comparable figures for spine related surgery were 81.8 and 48.5% with a low of 58.3 and 50.0% for foramen magnum-cervical surgery and a high of 93.8 and 43.8% for thoracolumbar procedures. The expressed perception of lack of satisfaction varied not only by procedure but by diagnosis. Overall, patients perceived a high level of post-surgical improvement, although a number experienced subsequent deterioration and the need for further intervention.

Growth in diastrophic dysplasia

OBJECTIVE

To study the growth and its correlates in diastrophic dysplasia (DTD) and to construct standard growth curves for DTD.

METHODS

Growth data of 121 Finnish patients with DTD were collected. Percentile growth curves for height and relative weight were constructed by using interpolated values from individual curves. Pubertal growth, intrafamilial variability, and correlates of adult height were assessed.

RESULTS

The median adult height was 135.7 cm for the male and 129.0 cm for the female subjects. The growth failure was progressive partly because of absent or weak pubertal growth spurt. The severity of the growth failure varied greatly, even among siblings. The final height did not correlate with the midparental height but correlated well with the height at 1.0 and 5.0 years. The relative weight was normal in childhood but increased before puberty; 28% of the adults were overweight. Head circumference was normal.

CONCLUSIONS

DTD interferes profoundly with normal growth and results in progressive growth failure of varying severity. The growth charts should prove useful in following up an individual patient with DTD; they may be used to predict adult height and to evaluate growth-promoting therapies.

Prenatal diagnosis of diastrophic dysplasia with polymorphic DNA markers

Ultrasonography is a non-invasive method for prenatal detection of diastrophic dysplasia (DTD) in the second trimester of pregnancy. As there is a need for genetic counselling as early as possible we wished to develop a method based on molecular analysis. Five fetuses in families with a previous history of DTD were studied by typing them and their relevant family members for DNA markers closely linked to the DTD gene. The DNA analyses predicted that three of the fetuses were unaffected and two affected. These results were concordant with those obtained by ultrasonography, and the phenotype of the fetus was correctly predicted in all cases. DNA analysis provides a reliable means of prenatal diagnosis in the first trimester of pregnancy.