Evaluation of muscle strength in patients with osteogenesis imperfecta

Değirmenci Karaahmetoğlu F.G., Evaluation of Muscle Strength in Patients with Osteogenesis Imperfecta. Hacettepe University Faculty of Medicine, Department of Internal Medicine, Ankara, 2024. Osteogenesis imperfecta (OI) is an inherited connective tissue disorder characterized by a defect in type 1 collagen synthesis, leading to increased bone fragility. In addition to pathological bone fractures, an increase in muscle abnormalities has also been observed in these patients. The proximity of bone and muscle during embryonic development and their anatomical and functional relationship in adult life are thought to be the main mechanisms underlying the muscle pathologies seen in OI patients. However, clinical studies investigating sarcopenia in OI patients are insufficient.The aim of this study was to investigate the incidence of sarcopenia in OI patients and the possible factors associated with sarcopenia. For this purpose, 17 OI patients and 17 healthy controls matched for age, gender, height, and body weight were included in the study. The groups were compared based on ultrasonographic measurements, handgrip strength, the International Physical Activity Questionnaire (IPAQ), upper and lower extremity functional indices (UEFI and LEFI), the simple sarcopenia screening form (SARC-F) score, and laboratory findings. Factors associated with handgrip strength in OI patients were investigated using statistical methods.The average handgrip strength of the left hand in patients was found to be significantly lower than that of the control group (21.8±4.9 kg vs. 25.3±4.2 kg, p=0.034). No significant differences were found between the groups in terms of median UEFI, LEFI, and SARC-F scores (p=0.245; p=0.259; and p=0.114, respectively). There were no significant differences in the average posterior thigh skin thickness, gastrocnemius thickness, and gastrocnemius pennation angle between OI patients and healthy controls.In OI patients, increasing age and female gender were associated with lower handgrip strength. A positive correlation was found between handgrip strength and UEFI (right hand: r=0.536, p=0.026; left hand: r=0.523, p=0.031). A negative correlation was found between right hand handgrip strength and thigh fat tissue thickness (r=-0.604, p=0.010), and a positive correlation with gastrocnemius thickness (r=0.592, p=0.012). Handgrip strength was negatively correlated with serum free T4 levels, while positively correlated with serum calcium, albumin, and triglyceride levels.In conclusion, despite the small number of patients, our study demonstrated an increase in the incidence of sarcopenia in OI patients. In the follow-up of these patients, muscle strength should be evaluated alongside blood tests and the number of fractures, and necessary precautions should be taken to address sarcopenia. Key words: Osteogenesis imperfecta, muscle strength, sarcopenia.