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Y. Harada, A. Inui, Y. Mifune, H. Nishimoto, T. Kokubu, Fujioka Hiroyuki, R. Kuroda (2019)Treatment of Locking of the Metacarpophalangeal Joint of the Thumb
Journal of Hand and Microsurgery, 12
K. Yamanaka, K. Yoshida, H. Inoue, A. Inoue, T. Miyagi (1985)Locking of the metacarpophalangeal joint of the thumb.
The Journal of bone and joint surgery. American volume, 67 5
Shun-Yao Wu, Sen-Yung Liu, T. Wei (2014)Early sonographic diagnosis and successful management of the sesamoid bone locking in the thumb.
American journal of physical medicine & rehabilitation, 93 5
G. Xiong, Yang Gao, S. Guo, L. Dai, K. Liu (2015)Pathoanatomy and treatment modifications of metacarpophalangeal joint locking of the thumb
Journal of Hand Surgery (European Volume), 40
(2005)Locking of thumb MP joint -morphological risk factors
(1988)Locked metacarpo-phalangeal joint of the thumb
J Hand Surg Br, 13
G. Inoue, T. Miura (1988)Locked Metacarpo-Phalangeal Joint of the Thumb
Journal of Hand Surgery (British and European Volume), 13
Ryoe Yoshida, H. House, R. Patterson, M. Shah, S. Viegas (2003)Motion and morphology of the thumb metacarpophalangeal joint.
The Journal of hand surgery, 28 5
S. Desai, W. Morgan (1991)Locked thumb metacarpophalangeal joint caused by sesamoid entrapment.
The Journal of hand surgery, 16 6
H. Togt (2003)Publisher's Note
J. Netw. Comput. Appl., 26
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Background: A locked thumb metacarpophalangeal joint is a rare condition that presents as restricted joint motions with mild hyperextension deformity, usually after a relatively minor hyperextension injury. Owing to the limitations of radiographs, computed tomography is a useful diagnostic imaging modality for assessing sesamoid displacement. However, despite its convenience, ultrasound findings of the locked thumb have rarely been reported. Here, we report a case of a locked thumb metacarpophalangeal joint diagnosed and followed-up using ultrasound. Case presentation: A 15-year-old boy with a locked thumb metacarpophalangeal joint presented to our hospital. On physical examination, the 1st metacarpophalangeal joint was found to be hyperextended, and active and passive flexions were not possible. While radiographs were inconclusive, ultrasound revealed radial sesamoid entrapment at the 1st metacarpophalangeal joint causing locking. After closed manual reduction, metacarpophalangeal motions recovered. Success of the reduction was also confirmable by ultrasound. Conclusions: Ultrasound can be a feasible modality to diagnose a locked thumb metacarpophalangeal joint and immediately judge the success or failure of the reduction. Keywords: Locked thumb, Metacarpophalangeal joint, Sesamoid, Ultrasound Background considered to be possible causes of locking [1, 3]. Closed Locking of the thumb metacarpophalangeal (MP) joint reduction can be attempted initially, but open reduction refers to a condition that causes a fixed state of the MP is often required, particularly when the presentation or joint with a slight hyperextension deformity and motion diagnosis is delayed . In the absence of clinical infor- restriction [1–5]. It can result from relatively minor mation, radial sesamoid movement or entrapment at the hyperextension injuries. Although there are some con- 1st MP joint is often overlooked on routine anteropos- troversies, an incarcerated volar plate, accessory collat- terior and lateral radiographs because of the bony over- eral ligament, or entrapped radial sesamoid are lap and variable degree of normal range of motion of the 1st MP joint . Therefore, computed tomography (CT) is preferred for diagnosing a locked thumb to evaluate * Correspondence: firstname.lastname@example.org Division of Hand Surgery & Reconstructive Microsurgery, Department of the location and status of the sesamoid [4, 5]. Although Orthopedic Surgery, Korea University Anam Hospital, Korea University CT is an excellent modality to assess bony details, it College of Medicine, 73, Goryeodae-ro, Seongbuk-gu, Seoul 02841, South causes radiation exposure and has a lower accessibility Korea Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Ahn et al. BMC Musculoskeletal Disorders (2020) 21:509 Page 2 of 5 compared to ultrasound (US). US findings of a locked distal displacement of the radial sesamoid was visualized thumb have rarely been reported. Here, we report a case (Fig. 3a). In addition, a flat articular surface and promin- of a locked thumb MP joint in a patient with successful ent radial condyle of the metacarpal head were observed. manual reduction in whom US findings before and after We decided to attempt a closed manual reduction at the the reduction were useful to diagnose the disease and outpatient clinic under US guidance instead of a reduc- confirm the success of the treatment. We also discuss tion under fluoroscopic guidance. After inducing local the feasibility of US and whether US can replace CT for anesthesia with 1% lidocaine, closed manual reduction diagnosing and managing the locked thumb MP joint. was attempted. After hyperextending the MP joint, con- tinuous axial pressure was applied toward the metacar- Case presentation pal head, and subsequently, flexion of the MP joint was A 15-year-old boy complained of pain in the right performed. The radial sesamoid was relocated with a thumb MP joint after a hyperextension injury while play- snapping sound, and MP joint motion recovered. At that ing 2 weeks before. He was diagnosed with a ligament spot, we confirmed on US that the radial sesamoid injury by an orthopedic surgeon at the first visit and re- returned to its place (Fig. 2b). A remo4vable thumb ferred to our hospital because his symptoms did not im- spica splint was applied for 2 weeks. Follow-up CT prove. On physical examination, the 1st MP joint was showed successful reduction of the radial sesamoid (Fig. slightly hyperextended, and passive and active flexions 3b). During 3 months of follow-up, the patient did not were not possible. Radiographs showed a hyperextended have any recurrence. posture at the 1st MP joint at approximately 30°. There were no definite abnormal findings on the first antero- Discussion and conclusions posterior and lateral radiographs (Fig. 1). However, the A locked thumb MP joint is rare. After mild hyperexten- clinical situation of the patient raised suspicion of a sion traumas of the MP joint, an inability to active or locked thumb MP joint, and we performed US. Distal passive flexion is characteristic [3–5]. The cause of lock- displacement of the radial sesamoid was noted on US ing is unclear. Yamanaka et al. suggested that tearing of (Fig. 2a). Although limited, there were no conspicuous the proximal volar plate or accessory collateral ligament, abnormalities in the volar plate or radial accessory col- which forms a constricting bundle over the distal meta- lateral ligament on US. CT was also performed to ensure carpal head, may cause locking . Desai et al. reported the diagnosis and evaluate the bony details. On CT, entrapment of the sesamoid bone between the proximal Fig. 1 Anteroposterior (a) and lateral (b) radiographs of the right thumb. The lateral radiograph shows a hyperextension posture of the metacarpal joint at approximately 30°. The abnormal location of the radial sesamoid (arrow) is difficult to recognize on radiographs because of bony overlaps Ahn et al. BMC Musculoskeletal Disorders (2020) 21:509 Page 3 of 5 Fig. 2 Longitudinal scan of ultrasound on volar surface of the 1st metacarpophalangeal joint shows distal displacement of the radial sesamoid bone (arrow) into the joint space (a). After reduction, the radial sesamoid has relocated to the radial condyle of the metacarpal head (b). P: proximal phalangeal base, MC: metacarpal head phalangeal base and the metacarpal head, which head was a risk factor for locking . The non-round causes locking . Xiong et al. suggested that radial shape of the articular surface and bony prominence sesamoid entrapment under the flexor pollicis brevis of the radial condyle of the metacarpal head were ob- and abductor pollicis brevis can block flexion, which served with a high incidence among cases of locked results in locking . Whether sesamoid entrapment thumb [1, 7]. The sharp proximal edge of the sesam- is primary or secondary, it is an essential landmark oid is also suspected as a risk factor because it can for evaluating a locked thumb MP joint and can be a easily damage and tear the membranous portion of sentinel for adjacent soft tissue injuries. Inoue et al. the proximal volar plate, which results in distal dis- reported that the bony morphology of the metacarpal placement and locking . Fig. 3 Sagittal reformation image of computed tomography (a) shows proximal displacement of the radial sesamoid (arrow). Note the non-round (flat) articular surface (arrow heads), prominence of the radial condyle of the metacarpal head (asterisk), and sharp proximal edge of the radial sesamoid. After reduction, the radial sesamoid (arrow) has relocated (b) Ahn et al. BMC Musculoskeletal Disorders (2020) 21:509 Page 4 of 5 Despite evident clinical symptoms, radiographs play a [1–4]. Sesamoid excision is not recommended unless limited role in recognizing radial sesamoid displacement there is a cartilage depression on the metacarpal head or due to bony overlap. Most reports described distal and significant stripping of the sesamoid from the volar plate radial displacements of the sesamoid as an imaging find- . ing of a locked thumb [1, 3]. Although the normal In conclusion, the locked thumb MP joint is a rare hyperextension posture can cause distal sliding of the condition, but an accurate diagnosis is essential. For sesamoid, prominent or asymmetric radial sesamoid dis- clinical information of a hyperextension injury at the placement can be a sign of a locked thumb. US can eas- MP joint and restricted passive motion, the radial sesam- ily identify the location of the radial sesamoid when oid should be examined with a high index of suspicion. radiographs are inconclusive or limited. To the best of US can be considered before CT or MRI for prompt our knowledge, US findings of a locked thumb MP joint diagnosis and reduction assessment for a locked thumb have been reported only as a vignette . Distal dis- MP joint. placement of the radial sesamoid can be a finding of a Abbreviations locked thumb. Although we were unavailable at the time MP: Metacarpophalangeal; CT: Computed tomography; US: Ultrasound; of diagnosis, a hockey stick transducer with a high fre- MRI: Magnetic resonance imaging quency of over 12 MHz may be helpful for demonstrat- Acknowledgements ing soft tissue or cartilaginous lesions of the locked Not applicable. thumb, such as proximal volar plate tears, accessory col- lateral ligament abnormalities, and groove-like cartilage Authors’ contributions depression at the metacarpal head, all of which have This work was carried out in collaboration between all authors. ICC and JWP designed the study; ICC and KSA analyzed the data; KSA and CHK wrote the been described in surgical cases [1–4]. Further, US has manuscript. All authors read and approved the final manuscript. the advantages of high accessibility and real-time nature. An experienced physician can attempt closed reduction Funding Not applicable. under US guidance and confirm the success or failure of the reduction immediately. CT is useful for evaluating Availability of data and materials bony details of the MP joint, including the shape of the This is a case report of a single patient, to protect privacy and respect articular surface, radial condyle of the metacarpal head, confidentiality; none of the raw data has been made available in any public repository. The original reports, imaging studies and outpatient clinic records or edge shape of the sesamoid, which are known as risk are retained as per normal procedure within the medical records of our factors for the locked thumb MP joint. The direct cor- institution. tical abutment of the sesamoid and metacarpal head may indicate cartilage damage . In our case, a flat Ethics approval and consent to participate Not applicable. metacarpal head and prominent radial condyle of the metacarpal head were observed on CT. We believe that Consent for publication US has the advantage of immediacy in diagnosis and A written, signed informed consent to publish this case and any accompanying images was obtained from the parent of the patient. treatment assessment over CT or magnetic resonance imaging (MRI) and is sufficiently replaceable. On the Competing interests other hand, however, US has a limitation arising from The authors declare that they have no competing interests. operator dependency. Experienced physician who has Author details knowledge of this disease and familiar with US can per- Department of Radiology, Korea University Anam Hospital, Korea University form this kind of diagnosis. Further imaging study such College of Medicine, Seoul, South Korea. Division of Hand Surgery & as CT or MRI can be considered for irreducible cases, Reconstructive Microsurgery, Department of Orthopedic Surgery, Korea University Anam Hospital, Korea University College of Medicine, 73, which require open reduction to evaluate the anatomic Goryeodae-ro, Seongbuk-gu, Seoul 02841, South Korea. details of the metacarpal head and sesamoid to decide the surgical plan, such as shaving of the radial condyle Received: 4 May 2020 Accepted: 27 July 2020 prominence or excision of the sesamoid. The treatment and clinical course of the locked thumb References MP joint can vary. Some patients are treated completely 1. Yamanaka K, Yoshida K, Inoue H, Inoue A, Miyagi T. Locking of the without recurrence by manual reduction alone, but some metacarpophalangeal joint of the thumb. J Bone Joint Surg Am. 1985;67: 782–7. fail to be treated with closed reduction and require open 2. Inoue G, Miura T. Locked metacarpo-phalangeal joint of the thumb. J Hand reduction. In surgery, excision of the incarcerated volar Surg Br. 1988;13:469–73. plate or accessory collateral ligament, shaving of the 3. Desai SS, Morgan WJ. Locked thumb metacarpophalangeal joint caused by sesamoid entrapment. J Hand Surg Am. 1991;16:1052–5. bony prominence of the radial condyle of the metacarpal 4. Xiong G, Gao Y, Guo S, Dai L, Liu K. Pathoanatomy and treatment head, or partial cutting of the flexor pollicis brevis can modifications of metacarpophalangeal joint locking of the thumb. J Hand be performed to release locking and restore the motion Surg Eur Vol. 2015;40:68–75. Ahn et al. BMC Musculoskeletal Disorders (2020) 21:509 Page 5 of 5 5. Harada Y, Inui A, Mifune Y, Nishimoto H, Kokubu T, Hiroyuki F, et al. Treatment of locking of the Metacarpophalangeal joint of the thumb. J Hand Microsurg. 2020;12:62–6. 6. Yoshida R, House HO, Patterson RM, Shah MA, Viegas SF. Motion and morphology of the thumb metacarpophalangeal joint. J Hand Surg Am. 2003;28:753–7. 7. Inoue S, Tsuboi K. Locking of thumb MP joint -morphological risk factors. Japan Soc Surg Hand. 2005;22:101–7. 8. Wu SY, Liu SY, Wei TS. Early sonographic diagnosis and successful management of the sesamoid bone locking in the thumb. Am J Phys Med Rehabil. 2014;93:455. Publisher’sNote Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
BMC Musculoskeletal Disorders – Springer Journals
Published: Jul 31, 2020
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