BACKGROUND: Stickler syndrome (SS) is a connective tissue disorder of fibrillary collagen with very variable clinical manifestations, including premature osteoarthritis and osteopenia. This musculoskeletal alteration may affect gait maturity or produce strength difficulties.
OBJECTIVE: Our aim was to describe the musculoskeletal characteristics, bone stiffness, gait kinematics, and kinetics of SS patients.
METHODS: This is a cross-sectional study of children and youngsters with SS recruited by telephone calls through the Spanish SS Association. All participants underwent an analysis of musculoskeletal characteristics, including a 3D gait analysis.
RESULTS: The sample included 26 SS patients, mainly boys (65.4%) with a median age of 11 (IQR 5-14). The manual muscle testing was normal in 88.5% of patients. The median distance covered in the 6-min walking test was 560.1 ± 113.4 m. Bone stiffness index scores were 70.9 ± 19.7 for children under 10 years and 88.3 ± 17.5 for children older than 10 years. The gait indicators GPS and GDI were: 7.4 ± 1.9 and 95.3 ± 9.7, respectively, for the left side and 6.8 ± 2.0 and 97.7 ± 9.5 for the right side, respectively.
CONCLUSIONS: In our series of patients with SS, we found muscle-articular involvement does not have a high impact on strength or gait problems. More work is needed to understand the effect of SS on the musculoskeletal system.

The Stickler syndrome (SS) has been described as a \"hereditary progressive arthro-ophtalmopathy\" by Stickler in 1965, due to mutations on the collagen genes. Currently about 40 different genes have been identified which encode for at least 27 different collagens. The majority of mutations occur in the COL2A1 gene on chromosome 12q13 (SS type I). Mutations in COL11A1 are less frequent (SS type II). More recently, mutations in COL11A2 and in the COL9A1 gene have been reported with particular phenotypes. The main features of this autosomal inherited disease are ocular, auditory with orofacial abnormalities and early-onset osteoarthritis. We report the clinical presentation of an adult and his son, with a particular focus on the bone status of the father, radiography, bone densitometry and transiliac bone biopsy showing that he was suffering from osteoporosis. The lumbar bone mineral density was low with a Z-score at -2.9. Transiliac bone biopsy showed a dramatic decrease of trabecular bone volume (8.6%; Nl: 19.5±4.9%), thin trabeculae and a disorganized trabecular network. A slight increase of osteoid parameters was observed. Bone resorption was markedly increased with an excessive number of active (TRAcP+) osteoclasts. The cortical width was normal, but a slight increase of cortical porosity was found. Osteoporosis has been rarely described in the SS. It might be useful to systematically perform a bone densitometry in all patients with SS and to discuss the indication of a transiliac bone biopsy in severe cases.