en جراحی دست / آرنج Hand surgery / Elbow گزارش مورد Case Report Closed dislocation of thumb Interphalangeal (IP) joint is rare, due to the inherent stability of the thumb IP joint. The interposition of the volar plate, flexor pollicis longus, sesamoids, and digital nerves can treat the joint closed reduction. In this study, we report a case of three-week-old irreducible closed dislocation of thumb IP joint in a 33-year-old woman. We planned to perform open reduction surgery using a dorsal approach on the IP joint and the ulnar side opening. The volar plate was interposed in the joint. Seven months after surgery, the patient achieved 0-45 degrees of IP range of motion. No sign of degenerative joint changes on the x-ray images was observed in the final visit. This study suggests the high probability of open reduction for these injuries and recommends the use of dorsal approach, excluding the complications of volar approach. Thumb dislocation, Irreducible, Interphalangeal joint 201 206 http://jros.iums.ac.ir/browse.php?a_code=A-10-770-2&slc_lang=en&sid=1 Farid Najd Mazhar fnajdmazhar@yahoo.com 10031947532846005672 10031947532846005672 No Bone and Joint Reconstruction Research Center, Shafa Orthopedic Hospital, Iran University of ‎Medical Sciences, Tehran, Iran. Hooman Shariatzadeh shariatzadeh_h@hotmail.com 10031947532846005673 10031947532846005673 No Bone and Joint Reconstruction Research Center, Shafa Orthopedic Hospital, Iran University of ‎Medical Sciences, Tehran, Iran. Meysam Fathi Choghadeh mchfathi@gmail.com 10031947532846005674 10031947532846005674 Yes Bone and Joint Reconstruction Research Center, Shafa Orthopedic Hospital, Iran University of ‎Medical Sciences, Tehran, Iran. Farhad Soltani farhad83soltani@gmail.com 10031947532846005675 10031947532846005675 No Bone and Joint Reconstruction Research Center, Shafa Orthopedic Hospital, Iran University of ‎Medical Sciences, Tehran, Iran.