Morpho-Functional Musculoskeletal Dysplastic Changes and Impaired Biomechanics Associated with Recurrent Joint Dislocations in Young Athletes: Assembling the Dysplastic Phenotype Puzzle for Early Identification—Cross-Sectional Study

Background: Joint dislocations/subluxations are an extremely common serious problem confronting athletes. Repeated joint injuries lead to the development of chronic musculoskeletal diseases and early disability. An important factor in preventing joint re-dislocations/subluxations is the early identification of an underlying predisposition to joint injuries. Therefore, it seemed relevant to identify diagnostically significant morpho-functional musculoskeletal dysplastic signs associated with repeated joint dislocations/subluxations and to assess their diagnostic value in identifying individuals with joint re-injury. Methods: Comprehensive clinic-phenotypic examination was conducted on 538 young adults (aged 18–35 years) involved in mass sports. The study was reported in accordance with the STROBE and STARD 2015 guidelines. Results: The repeated sports-related joint dislocations/subluxations were observed in 10.4% (95% CI: 8.0–13.3). All 56 participants with recurrent joint dislocations/subluxations had connective tissue dysplasia syndrome, compared with 71.2% of those without them (p < 0.001). The dysplastic severity discriminated participants with and without joint re-dislocations/subluxations (AUC = 0.839; 95% CI: 0.773–0.906, p < 0.001). A total connective tissue dysplasia score of 35.91 or higher raised the probability of a joint re-dislocation/subluxation history from 10.4% to 28.9% (sensitivity 78.6%, specificity 77.6%, positive likelihood ratio 3.5), whereas a lower score made it unlikely (negative predictive value 96.9%). The dysplastic phenotype associated with a predisposition to joint dislocations/subluxations has characteristic dysplastic signs, which, when considered together, could form the basis for the developing screening method to identify individuals prone to such recurrent joint instability. Conclusions: The obtained results provide a practical tool for sports practitioners to identify athletes who need closer assessment and, after prospective validation, to implement preventive measures in a targeted manner supporting personalized strategies to preserve musculoskeletal health in young athletes.