Tehran University of Medical Sciences Journal of Orthopedic and Spine Trauma 2538-2330 9 3 2023 10 10 149 51 Ramin Shayan-Moghadam Center for Orthopedic Trans-Disciplinary Applied Research, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran Mohammadhasan Sharafi Department of Orthopedic and Trauma Surgery, Shariati Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Ehsan Mahmoudi Department of Orthopedic and Trauma Surgery, Shariati Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mohammad Hossein Nabian Department of Orthopedic Surgery, Center for Orthopedic Trans-Disciplinary Applied Research, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran 2022 08 19 2023 02 25 Background: Familial synovial hypertrophy is a rare condition presenting as the flexion contracture of the small joints of the hands and feet, in addition to the large joint effusion and range of motion (ROM) restriction. Case Report: Herein, we introduce a 14-year-old boy with a long history of deformities in the hand and foot joints. Painless swelling and limited motion of big joints were present since birth. There were no similar diseases in paternal or maternal relatives, while his 9-year-old brother also had a lifelong history of same deformities. Conclusion: Involvement of the hands and feet can severely restrict young patients’ function in daily tasks, raising the importance of early diagnosis and treatment in familial synovial hypertrophy. https://jost.tums.ac.ir/index.php/jost/article/view/419 https://jost.tums.ac.ir/index.php/jost/article/download/419/329