Developmental dysplasia of the hip (DDH) is characterized by varying degrees of underdevelopment of the hip joint (HJ) and para-articular tissues with numerous variants of clinical and anatomical criteria. It is now considered one of the manifestations of undifferentiated connective tissue dysplasia (UCTD), which is confirmed by genetic testing. Undoubtedly, children with DDH also have other manifestations of UCTD, the clinical combination of which must be taken into account for the overall prognosis of the patient's quality of life, as well as the determination of control points in the treatment and prevention of the disease. Materials and methods of research: a singlestage observational screening study was carried out involving 785 children (578 girls and 207 boys) from 2 to 14 years old (7,5±1,5 years) with a radiographically confirmed diagnosis of DDH of various variants (torsion-valgus deformity, subluxation , dislocation in the vehicle). The control group consisted of 259 children (140 girls and 119 boys) without HJ pathology, who were examined at the Research Institute of Traumatology, Orthopedics and Neurosurgery for preparation for a kindergarten/school/sports section, comparable in age (6,5±1,3 years). The criteria for selecting UCTD was the Bayesian classifier modified by T.I. Kadurina and V.N. Gorbunova, including the 50 most common clinical markers. For analysis the clinical anamnestic method, instrumental data of somatic symptom disorder test was used. Results: after summing up the scores in children with DDH, grade I UCTD was diagnosed in 40,0% (314), grade II – in 36,1% (283) and grade III – in 23,9% (188). In most cases, symptoms of UCTD with an Ehlers-Danlos-like syndrome were noted, which are characterized by changes in the musculoskeletal system, skin, connective tissue elements of internal organs (hypermobility of the joints, stretchable skin, anatomical disorders of the heart valves, bile ducts, etc.) or signs of UCTD with an unclassifiable phenotype when there is a variety of stigmas. All children in this group have joint hypermobility, myotonic syndrome, and various types of posture disorders. In the control group with DDH, 27,4% (71) noted the burdened heredity in the pathology of the musculoskeletal system on the mother's or father's side. In the control group the signs of UCTD stigma were also diagnosed, however, the degree of their severity and occurrence were significantly lower (p<0,05). In these children, the most significant were changes in the organ of vision, nervous system, maxillofacial region, digestive tract and a decrease in immune function. Conclusion: manifestations of UCTD are significantly more common in children with DDH compared with healthy children; pathology of the musculoskeletal and cardiovascular systems prevails in the structure of UCTD stigmas. In the pathogenesis of DDH, a genetic predisposition is realized (45,5%, 357 children), hypermobility of joints, myatonic syndrome were observed in all children in the study group. Manifestations of UCTD were also found in the control group, however, the stigmas were of a visceral nature of lesions and impairments from the sense organs, which is not the subject of a pediatric orthopedist's study. Thus, the features of UCTD in children with DDH are considered as a predictor of the pathology severity.
The role of polymorphic variants of matrix metalloproteinases genes in the formation of disruption of connective tissue homeostasis and pathology of the musculoskeletal system.
