Unstable Occult Scaphoid Fracture Diagnosed by Dynamic Point-of-Care Ultrasound: A Case Report and Review

Yong-hyun Yoon^1,2,3*Jihyo Hwang⁴King Hei Stanley Lam^5,6,7*Jeimylo Cristobal De Castro^8,9Teinny Suryadi^10,11,12Anwar Suhaimi¹³CHUN WEI KANG¹⁴Howon Lee¹⁵Hyeongjik Kim^16,3Seungbeom Kim^17,3Daniel Chiung-Jui Su^18,19

• ¹Kangnam Sacred Heart Hospital, Seoul, Republic of Korea
• ²Incheon Terminal Orthopedic Surgery Clinic, Inha-ro 489beon-gil, Namdong-gu, Incheon 21574 , Republic of Korea, Incheon, Republic of Korea
• ³International Academy of Regenerative Medicine , Inha-ro 489beon-gil, Namdong-gu, Incheon 21574, Republic of Korea, Incheon, Republic of Korea
• ⁴Hallym University Kangnam Sacred Heart Hospital, Yeongdeungpo-gu, Republic of Korea
• ⁵The University of Hong Kong Faculty of Education, Hong Kong, Hong Kong, SAR China
• ⁶The Chinese University of Hong Kong, Hong Kong, Hong Kong, SAR China
• ⁷⁠Board of Clinical Research, the International Association of Musculoskeletal Medicine, hongkong, Hong Kong, SAR China
• ⁸SMARTMD Center for Non-surgical Pain Interventions, manila, Philippines
• ⁹Adventist University of the Philippines, Silang, Philippines
• ¹⁰Department of Physical Medicine and Rehabilitation, Hermina Podomoro Hospital, North Jakarta, Indonesia., North Jakarta, Indonesia
• ¹¹Department of Physical Medicine and Rehabilitation, Medistra Hospital, South Jakarta, Indonesia., South Jakarta, Indonesia
• ¹²Physical Medicine and Rehabilitation, Synergy Clinic, West Jakarta, Indonesia, West Jakarta, Indonesia
• ¹³Universiti Malaya Department of Rehabilitation Medicine, Federal Territory of Kuala Lumpur, Malaysia
• ¹⁴Taipei Medical University, Taipei City, Taiwan
• ¹⁵Kangdong Sacred Heart Hospital, Gangdong-gu, Republic of Korea
• ¹⁶Ahyeon orthopedic clinic B270 Sinchon-ro, Mapo-gu,Seoul, Seoul, Republic of Korea
• ¹⁷Miso pain clinic, 1569, Bongyeong-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16703, Republic of Korea, Suwon, Republic of Korea
• ¹⁸Chi Mei Medical Center, Yongkang District, Taiwan
• ¹⁹Tempo Regeneration Center for Musicians, Tainan 700, Taiwan, Tainan, Taiwan

Background: The scaphoid is the most frequently fractured carpal bone, yet its diagnosis remains a significant clinical challenge. A substantial percentage of non-displaced fractures are missed on initial radiographs, leading to delays in treatment and an increased risk of serious long-term complications such as non-union and avascular necrosis. While advanced imaging like CT and MRI are highly accurate, they are associated with higher costs, radiation exposure (CT), and limited immediate availability. High-resolution musculoskeletal ultrasound has emerged as a rapid, non-invasive, and cost-effective alternative. Its unique ability to perform dynamic, real-time assessment of fracture stability offers a significant advantage over static imaging modalities. Case Presentation: A 29-year-old woman presented to our outpatient clinic with acute left wrist pain following a traction-fall injury. An initial four-view radiographic series of the wrist revealed no definitive evidence of a fracture. Despite the negative imaging, clinical suspicion remained high due to persistent, exquisite point tenderness over the anatomical snuffbox. A point-of-care musculoskeletal ultrasound examination was performed, which revealed a clear hypoechoic cortical breach at the scaphoid waist. To assess mechanical stability, a dynamic stress maneuver—defined as a gentle, controlled 'heel-toe' probe rocking that applies focal pressure across the fracture—was performed under real-time sonographic visualization. Gentle probe pressure combined with passive ulnar deviation of the wrist demonstrated visible gapping and micromotion at the fracture site, confirming it as mechanically unstable. Based on this definitive finding, the diagnosis was revised to an unstable occult scaphoid waist fracture, and the management plan was immediately upgraded to a rigid thumb spica splint. Long-term follow-up over two years showed radiographic and sonographic evidence of a stable fibrous union. Conclusions: This case report highlights the pivotal role of dynamic musculoskeletal ultrasound as an adjunct in the diagnostic algorithm for acute wrist trauma. It demonstrates its ability not only to identify a radiographically occult scaphoid fracture but, more critically, to provide immediate functional information about mechanical stability. This information is paramount for guiding appropriate and timely management to mitigate the risk of long-term complications. We advocate for the broader integration of dynamic ultrasound into the initial assessment of suspected scaphoid fractures.