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Sagittal Band Injury

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Other Names

  • Sagittal Band Injury
  • Boxer’s knuckle
  • Sagittal Band Rupture

Background

  • This page refers to sagittal band injuries of the hand, leading to dislocation of the extensor tendon

History

Epidemiology


Pathophysiology

  • General
    • Injury to the sagittal bands typically occurs from direct trauma
  • Boxer's Knuckle
    • Sagittal band injury that also ruptures the MCPJ capsule
    • Third MCP is most commonly affected[1]
  • Anatomic location
    • In boxers: most commonly index or middle in professionals, ring and little finger in amateurs
    • Location: index (14%), middle (48%), ring (7%), little (31%) (need citation)
    • Radial sagittal band affected most commonly (9:1 radio:ulnar)

Etiology

  • Acute
    • Blunt trauma to the MCP joint can cause partial tear or complete rupture of the sagittal bands
    • Forceful resisted flexion or extension
    • Laceration of the extensor hood
    • Low energy mechanisms including flicking the finger has been reported
  • Chronic
    • Inflammatory processes (such as rheumatoid arthritis)
    • Spontaneously during routine activities

Pathoanatomy

  • Sagittal Band
    • Component of the dorsal hood
    • Has both radial and ulnar bands
    • Support structure for the extensor tendon at the level of the dorsal metacarpophalangeal joint (MCP)[2]
    • Thickest structures of the extensor hood
    • Act as the main resistance for proximal displacement of the extensor tendon
    • Prevents radial-ulnar subluxation of the extensor tendon, aid in MCP extension
    • There is a superficial and deep layer; the extensor tendon runs through them
  • Dorsal Hood
    • In addition to sagittal bands, also composed of oblique and transverse bands

Risk Factors


Differential Diagnosis


Clinical Features

  • History
    • Patients most commonly will endorse punching an object with a clenched fist
    • Pain, swelling of the dorsal hand
    • Extensor tendon instability
    • Snapping localized to a specific MCP joint
    • Soreness of the MCP
  • Physical Exam
    • Swelling of the affected joint is often present, especially acutely
    • Evaluate for tendon subluxation or dislocation in both flexion and extension
      • The tendon tends to sublux in the ulnar direction with flexion of the MCPJ[3]
      • Snapping may be obvious or subtle
    • Loss of ability to initiate extension from a flexed position
      • Able to maintain MCP in extension once there
    • Pain may be worse when extending MCP joint against resistance with both IP joints extended
  • Special Tests

Evaluation

Radiographs

  • Standard Radiographs Hand
    • Should be obtained in all patients
    • Often normal unless there is an avulsion fracture
    • In rheumatoid arthritis, may show dropped fingers and ulnar deviation
  • Brewerton view
    • AP with dorsal surface of fingers touching the cassette and MCP joints flexed 45deg
  • Stress view
    • Evaluate for collateral ligament avulsion/injury

MRI

  • Indications
    • Confirm diagnosis
    • Evaluate for etiology (synovitis, etC)
  • Findings
    • Acute: poor definition, focal discontinuity and focal thickening
    • Ulnar defect: subluxation of extensor tendon in radial direction
    • Radial defect: dislocation of extensor tendon into ulnar intermetacarpal gully

Ultrasound

  • General
    • Useful when swelling limits exam
    • Useful for dynamic evaluation of the extensor tendon and sheath[4]
    • Can see subluxation of EDC tendon relative to metacarpal head on MCP flexion
  • Normal sagittal band
    • thin hyperechoic bands that join the extensor tendons at the MCP joint level.
  • Ruptured sagittal band[5]
    • Irregular thickening of the abnormal sagittal band with hypoechogenicity
    • The extensor tendon can appear normal or can become edematous with loss of the fibrillar pattern
    • Dynamically, the extensor tendon can be subluxed or dislocated during finger flexion

Classification

Rayan and Murray Classification

  • Type I[6]
    • No tear, bands are contused
    • Sagittal band injury without extensor tendon instability
  • Type II
    • Subluxation of the extensor tendon
    • Sagittal band injury with tendon subluxation
  • Type III
    • Sagittal band injury with tendon dislocation
    • Dislocation of the tendon between the metacarpal heads

Management

Nonoperative

  • Indications
    • Most cases, especially acute within the last 6 weeks
  • Immobilization in MCP Joint Extensor Splint
    • Maintains MCPJ in extension
    • Duration is typically 6 weeks
    • Hand therapy can make custom splints which block flexion
    • Buddy taping can be considered if there is no instability

Operative

  • Indications
    • Failure of conservative treatment
    • Continuation of subluxation or dislocation
    • Chronic injuries > 6 weeks
    • Professional athletes
  • Technique
    • Primary repair (Kettlekamp)
    • Realignment (extensor centralization procedure)

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play/ Work

  • Needs to be updated

Complications and Prognosis

Prognosis

  • Needs to be updated

Complications

  • MCP Flexion Contracture
    • Typically from delayed presentation or from non-operative treatment
    • Secondary intrinsic tightness develops

See Also


References

  1. Sivakumar, Brahman, et al. “Sagittal Band Injuries: A Review and Modification of the Classification System.” The Journal of Hand Surgery, vol. 47, no. 1, Jan. 2022, pp. 69–77. PubMed, https://doi.org/10.1016/j.jhsa.2021.09.011.
  2. Willekens, Inneke, et al. “Ultrasound Follow-up of Posttraumatic Injuries of the Sagittal Band of the Dorsal Hood Treated by a Conservative Approach.” European Journal of Radiology, vol. 84, no. 2, Feb. 2015, pp. 278–83. PubMed, https://doi.org/10.1016/j.ejrad.2014.11.001.
  3. Lin, James D., and Robert J. Strauch. “Closed Soft Tissue Extensor Mechanism Injuries (Mallet, Boutonniere, and Sagittal Band).” The Journal of Hand Surgery, vol. 39, no. 5, May 2014, pp. 1005–11. PubMed, https://doi.org/10.1016/j.jhsa.2013.11.018.
  4. Kleinhenz, Benjamin P., and Brian D. Adams. “Closed Sagittal Band Injury of the Metacarpophalangeal Joint.” The Journal of the American Academy of Orthopaedic Surgeons, vol. 23, no. 7, July 2015, pp. 415–23. PubMed, https://doi.org/10.5435/JAAOS-D-13-00203.
  5. Lee SA, Kim BH, Kim SJ, Kim JN, Park SY, Choi K. Current status of ultrasonography of the finger. Ultrasonography. 2016 Apr;35(2):110-23. doi: 10.14366/usg.15051. Epub 2015 Nov 24. PMID: 26753604; PMCID: PMC4825212.
  6. Matzon, Jonas L., and David J. Bozentka. “Extensor Tendon Injuries.” The Journal of Hand Surgery, vol. 35, no. 5, May 2010, pp. 854–61. PubMed, https://doi.org/10.1016/j.jhsa.2010.03.002.
Created by:
John Kiel on 23 July 2022 18:41:50
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Last edited:
23 July 2022 19:41:45
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