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Scapholunate Instability

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Other Names

  • Scapholunate Ligament Injury
  • Scapholunate Injury
  • Dynamic scapholunate instability
  • Rotatory subluxation of the scaphoid
  • Dorsal intercalated segment instability (DISI)
  • Scapholunate advanced collapse (SLAC)
  • Scapholunate Dissociation
  • Scapholunate diastasis
  • Scapholunate subluxation
  • Scapholunate gap
  • Terry Thomas sign
  • Scapholunate ligament tear
  • Scapholunate separation

Background

History

  • The first description of scapholunate dissociation is credited to Terry Thomas sign observations and early reports in the mid-20th century (need citation)
  • Landmark paper that established the pathophysiology and clinical understanding of scapholunate instability was published by Linscheid and Dobyns in 1972[1]

Epidemiology

  • Cumulative incidence of carpal instability is 44% within 2 years of trauma[2]
    • Scapholunate instability accounts for 24% of these cases
  • Another study of patients with abnormal wrist radiographs found 81% had pathologic scapholunate gap[3]
    • Bilateral radiographic findings are common and often asymptomatic
  • Demograhic data
    • Mean age in one study was 48[3]

Pathophysiology

Normal wrist radiograph with the scapholunate joint labeled
3D rendering of the SLL with the scaphoid removed to show the ligaments: dorsal (blue), proximal (yellow), volar (green) components[4]
Widening of the scapholunate interval (Terry Thomas sign) due to scapholunate ligament disruption. [5]
Static scapholunate instability – complete scapholunate ligament injury (gap ≥ 5 mm); A – without rotary subluxation of the scaphoid, B – with palmar subluxation of the scaphoid[6]

General

  • The most common form of carpal instability, results from injury to the scapholunate interosseous ligament
  • Tearing of the ligament leads to abnormal biomechanics, pain and progressive dysfunction
  • If untreated, it can result in a predictable pattern of wrist osteoarthritis termed scapholunate advanced collapse (SLAC)[7]
  • Treatment can be conservative for early, stable cases while unstable and chronic cases require surgical fixation

Etiology

  • Can be both an acute injury and a chronic condition
  • Direct trauma with wrist in extension and ulnar deviation[8]
    • This leads ito initial disruption of the SLIL
  • Many cases are not initially diagnosed at the time of injury
    • Initial presentation may not be until years later with a more chronic presentation
    • Patients may not even remember the specific injury or event

Pathophysiology

  • Arises from disruption of the scapholunate interosseous ligament (SLIL) and supporting stabilizers[7]
    • Subsequently, there is abnormal motion and alignment between the scaphoid and lunate
  • The dorsal band of the SLIL is most critical
    • Failure can cause the scaphoid to flex, pronate and sublux volarly
    • The lunate may extend and supinate
    • These results in a widened scapholunate gap and loss of synchronous carpal motion
  • Instability can be dynamic or static
    • Depends on extent of injury and involvement of the secondary stabilizers
    • As the injury progresses, abnormal kinematics can lead to increased load on the joints
    • When left untreated, will progress to degenerative arthritis/scapholunate advanced collapse (SLAC)

Spectrum of Disease

  • Listed in order of increasing severity
    • Dynamic scapholunate instability
    • Rotatory subluxation of the scaphoid
    • Scapholunate dissociation
    • Dorsal intercalated segment instability (DISI)
    • Scapholunate advanced collapse

Associated injuries

Anatomy of the Scapholunate Joint

  • Formed by the articulation of the scaphoid, lunate
  • Stabilized by the U- or C-shaped Scapholunate Ligament
    • Composed of 3 distinct components dorsal, volar (palmer) and proximal
    • Injury to the dorsal band is considered most significant in the risk of scapholunate instability

Risk Factors

Anatomic

  • Ulna minus configuation[10]
  • Slope of radial articular surface
  • Lunotriquetral coalition

Differential Diagnosis

Differential Diagnosis Wrist Pain

Clinical Features

Scaphoid Shift Test[11]

General

  • Patients will endorse wrist pain
  • Often following trauma such as a fall on outstretched hand
    • In more chronic cases, patients may not remember or describe the injury well
  • Swelling can be present
  • Pain is worse by grip, wrist extension, activities which load the wrist[12]
    • These symptoms are often progressive

Physical Exam: Physical Exam Wrist

  • Pain and tenderness along carpal bones, especially the dorsal scapholunate interval
    • This can be found just distal to listers tubercle
  • Swelling, decreased grip strength
  • Pain with extension or wrist loading
  • Clicking or clunking during wrist motion
  • In more advanced cases, reduced range of motion

Special Tests

Evaluation

Load video
YouTube
MRI in coronal plane showing scapholunate dissociation
Measurement of the scapholunate interval in the coronal plane[13]

Radiographs

  • Standard Radiographs Wrist
    • 3 views initially
    • Frequently missed due to normal appearance of initial radiographs
  • Scapholunate gap view
  • Clenched fist view: evaluate for dynamic wrist instability
  • Positive findings
    • Scapholunate gap widening (usually >3 mm)
    • Increased scapholunate angle (>60–70°)
    • Abnormal carpal alignment

CT

  • Give the best osseous evaluation of the bones
  • Arthrography provides high sensitivity and specificity for SLL tears
  • Four dimensional CT can be used for dynamic evaluation
  • 75-90% sensitivity, 80-95% specific[14]

MRI

  • Best evaluateion for soft tissue structures, staging[15]
  • Less sensitive than some of the advanced CT imaging
Arthroscopic scapholunate ligament injury classi- fication by Geissler et al[16]

Classification

Geissler's Classification[17]

  • Grade I
    • Attenuation and/or hemorrhage of the interosseous ligament as observed from RC space.
    • No incongruence of carpal alignment in MC space
    • Treatment: immobilization
  • Grade II
    • Attenuation and/or hemorrhage of the interosseous ligament as observed from RC space
    • Incongruence and/or step-off as observed from MC joint
    • A slight gap (less than the width of a probe, < 2 mm) between the carpal bones may be present
    • Treatment: reduction and pinning
  • Grade III
    • Incongruence and/or step-off of the carpal alignment are observed in both the RC, MC space
    • The probe may rotate and pass through the gap (> 2 mm) between the carpal bones
    • Treatment: arthroscopic reduction or open reduction and pinning or repair
  • Grade IV
    • Incongruence and/or step-off of the carpal alignment are observed in both the RC, MC space
    • Gross instability with manipulation is noted
    • Drive through phenomena: A 2.7-mm arthroscope may be passed through the gap between the bones
    • Treatment: open re-insertion or ligament reconstruction

Management

Methods of scapholunate interosseous ligament (SLIL) reconstruction. (A) The modified Brunelli technique (MBT). (B) Mark Henry's technique (MHT).[18]
Scapholunate (SL) advanced collapse after an SL injury, with subsequent arthritic changes at the radiocarpal and midcarpal joints (SL advanced collapse-SLAC III). Also note the volarflexed scaphoid, appearing triangular distally with the so-called 'ring sign'.[19]
SLAC wrist with further radiological progression (Stage III). Posteroanterior radiograph (a) and coronal and sagittal CT reformat images (b) of the same patient, as well as a coronal STIR MRI image of the wrist (c) in a different patient with SLAC wrist arthropathy.[20]

Nonoperative

  • Strongly encouraged to consult hand surgery with management decisions
  • Indications
    • Partial tears
    • Dynamic instability without malalignment, arthrosis
  • Activity modification[21]
  • Physical Therapy
  • NSAIDS
  • Wrist Splinting

Acute Operative Management (under 6 weeks)

  • Indications
    • Complete tears
    • Static instability
    • Failure of conservative management
  • Technique
    • Dorsal capsulodesis, using an open dorsal approach
    • K-wire fixation to maintain reduction

Chronic Operative Management (more than 6 weeks)

  • Indications
    • Chronic dynamic instability
    • Rotatory subluxation of the scaphoid
    • Scapholunate dissociation
    • Dorsal intercalated segment instability (DISI)
    • Scapholunate advanced collapse
  • Technique
    • Arthroscopic debridement
    • Percutaneous pinning
    • Ligamentoplasty
    • Mini-invasive dorsal repair
    • Less commonly, salvage procedures such as proximal row carpectomy or partial wrist fusion

Rehabilitation/ Return to Play

Postoperative Rehabilitation

  • Early phase[22]
    • Duration 0–4/6 weeks
    • Immobilization, edema control, and gentle passive range of motion as tolerated.
  • Intermediate phase[23]
    • Duration 4–8 weeks
    • Gradual progression to active range of motion, proprioceptive and neuromuscular retraining, and initiation of strengthening exercises
  • Late phase
    • Duration: 8+ weeks
    • Sport-or work-specific training and functional testing to ensure readiness for return to activity

Return to Play

  • At the discretion of the surgeon
  • There is no consensus on optimal return to play protocols

Prognosis/ Complications

Prognosis

  • General
    • Prognosis is garded
    • Risk of progression to carpal dysfunction and arthritis exists even if treated correctly
  • Surgical
    • Early surgical intervention is associated with lower failure rates[24]
    • Ligament repair and capsulodesis yielding lower failure rates and improved radiographic results compared to delayed or chronic intervention

Complications

  • Disease progression
    • Dynamic scapholunate instability
    • Rotatory subluxation of the scaphoid
    • Scapholunate dissociation
    • Dorsal intercalated segment instability (DISI)
    • Scapholunate advanced collapse
  • Persistent Pain
  • Grip Weakness
  • Functional complications
  • Wrist stiffness

See Also

Internal

External

References

  1. ↑ Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. The Journal of Bone and Joint Surgery (Am). 1972;54(8):1612–1632.
  2. ↑ O'Brien, Lisa, et al. "Cumulative incidence of carpal instability 12-24 months after fall onto outstretched hand." Journal of Hand Therapy 31.3 (2018): 282-286.
  3. ↑ 3.0 3.1 Picha, Brad M., Emmanuel K. Konstantakos, and Douglas A. Gordon. "Incidence of bilateral scapholunate dissociation in symptomatic and asymptomatic wrists." The Journal of hand surgery 37.6 (2012): 1130-1135.
  4. ↑ Image courtesy of radsource.us, "SLL Tear and DISI Deformity"
  5. ↑ Image courtesy of Case courtesy of The Radswiki, Radiopaedia.org, rID: 11913
  6. ↑ Elsaftawy, Ahmed. "Radial wrist extensors as a dynamic stabilizers of scapholunate complex." Polish Journal of Surgery 85.8 (2013): 452-459.
  7. ↑ 7.0 7.1 Wessel, Lauren E., and Scott W. Wolfe. "Scapholunate instability: diagnosis and management–anatomy, kinematics, and clinical assessment–part I." The Journal of Hand Surgery 48.11 (2023): 1139-1149.
  8. ↑ Mathoulin, Christophe, and Mathilde Gras. "Role of wrist arthroscopy in scapholunate dissociation." Orthopaedics & Traumatology: Surgery & Research 106.1 (2020): S89-S99.
  9. ↑ Bain, Gregory I., and Melanie Amarasooriya. "Scapholunate instability: why are the surgical outcomes still so far from ideal?." Journal of Hand Surgery (European Volume) 48.3 (2023): 257-268.
  10. ↑ http://www.wheelessonline.com/ortho/scapholunate_instability
  11. ↑ Chae, Seungbum, Youn-Tae Roh, and Il-Jung Park. "Scapholunate Dissociation: Current Concepts of the Treatments." Archives of Hand and Microsurgery 25.2 (2020): 77-89.
  12. ↑ White, Neil J., and Natalie C. Rollick. "Injuries of the scapholunate interosseous ligament: an update." JAAOS-Journal of the American Academy of Orthopaedic Surgeons 23.11 (2015): 691-703.
  13. ↑ Lans, Jonathan, et al. "Incidence and functional outcomes of scapholunate diastases associated distal radius fractures: a 2-year follow-up scapholunate dissociation." The open orthopaedics journal 12 (2018): 33.
  14. ↑ Orkut, Sinan, et al. "Assessment of scapholunate instability on 4D CT scans in patients with inconclusive conventional images." Radiology 308.3 (2023): e230193.
  15. ↑ Palisch, Andrew R., et al. "Preoperative and postoperative imaging of scapholunate ligament primary repair and modified brunelli reconstruction." RadioGraphics 42.1 (2022): 195-211.
  16. ↑ Delgado-Serrano, P. J., et al. "Arthroscopic reconstruction for unstable scaphoid non-union." Revista Española de Cirugía Ortopédica y Traumatología (English Edition) 61.4 (2017): 216-223.
  17. ↑ Geissler WB, Freeland AE, Savoie FH, McIntyre LW, Whipple TL. Intracarpal soft-tissue lesions associated with an intra-articular fracture of the distal end of the radius. J Bone Joint Surg [Am] 1996;78-A:357-365.
  18. ↑ Chae, Seungbum, et al. "Kinematic analysis of two scapholunate ligament reconstruction techniques." Journal of Orthopaedic Surgery 29.2 (2021): 23094990211025830.
  19. ↑ Andersson, Jonny K. "Treatment of scapholunate ligament injury: current concepts." EFORT Open reviews 2.9 (2017): 382-393.
  20. ↑ Tischler, Brian T., et al. "Scapholunate advanced collapse: a pictorial review." Insights into imaging 5.4 (2014): 407-417.
  21. ↑ White, Neil J., and Natalie C. Rollick. "Injuries of the scapholunate interosseous ligament: an update." JAAOS-Journal of the American Academy of Orthopaedic Surgeons 23.11 (2015): 691-703.
  22. ↑ Palisch, Andrew R., et al. "Preoperative and postoperative imaging of scapholunate ligament primary repair and modified brunelli reconstruction." RadioGraphics 42.1 (2022): 195-211.
  23. ↑ Ying, Qiuwen, et al. "Clinical Efficacy of Arthroscopic Transplantation of Palmaris Longus Tendon Combined with Early Accelerated Motion Rehabilitation After Scapholunate Ligament Reconstruction for Geissler Type IV Scapholunate Instability." Alternative Therapies in Health & Medicine 30.10 (2024).
  24. ↑ Rohman, Eric M., et al. "Scapholunate interosseous ligament injuries: a retrospective review of treatment and outcomes in 82 wrists." The Journal of hand surgery 39.10 (2014): 2020-2026.
Created by:
John Kiel on 18 June 2019 23:12:13
Authors:
Last edited:
21 October 2025 00:17:20
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