A scoring system for the assessment of clinical severity in osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility and fractures. Patients with OI have clinical features that may range from mild symptoms to severe bone deformities and neonatal lethality. Numerous approaches for the classification of OI have been published. The Sillence classification is the most commonly used. In this study, we aimed at developing a more refined sub-classification by applying a proposed scoring system for the quantitative assessment of clinical severity in different types of OI.

This study included 43 patients with OI. Clinical examination and radiological studies were conducted for all patients. Cases were classified according to the Sillence classification into types I-IV. The proposed scoring system included five major criteria of high clinical value: number of fractures per year, motor milestones, long bone deformities, length/height standard deviation score (SDS), and bone mineral density (BMD). Each criterion was assigned a score from 1 to 4, and each patient was marked on a scale from 1 to 20 according to these five criteria.

Applying the proposed clinical scoring system showed that all 11 patients with Sillence type I (100%) had a score between 6 and 10, denoting mild affection. The only patient with Sillence type II had a score of 19, denoting severe affection. In Sillence type III, 7 patients (31.8%) were moderately affected and 15 patients (68.2%) were severely affected. Almost all patients with Sillence type IV (88.9%) were moderately affected.

Applying the proposed scoring system can quantitatively reflect the degree of clinical severity in OI patients and can be used in complement with the Sillence classification and molecular studies.