questions
2

Sagittal Band Rupture (traumatic extensor tendon dislocation)

Author:
Topic updated on 08/18/14 11:58am
Introduction
  • Sagittal band (SB) rupture leads to dislocation of the extensor tendon post
    • also known as "boxer's knuckle"
  • Epidemiology
    • demographics
      • more common in pugilists
        • index and middle finger in professionals
        • ring and little finger in amateurs
    • location
      • the middle finger is most commonly involved
        • index 14%
        • middle 48%
        • ring 7%
        • little 31%
      • the radial SB is more commonly involved
        • radial:ulnar = 9:1
  • Mechanisms
    • traumatic
      • forceful resisted flexion or extension 
      • laceration of extensor hood  
      • direct blow to MCP joint
    • atraumatic
      • inflammatory (e.g. rheumatoid arthritis)  
      • spontaneously during routine activities
  • Associated conditions
    • MCP joint collateral ligament injuries
Anatomy
  • Extensor mechanism comprises
    • tendons
      • EDC/EIP/EDM
      • lumbricals
      • interossei
    • retinacular system
      • sagittal bands
        • the sagittal bands are part of a closed cylindrical tube (or girdle) that surrounds the metacarpal head and MCP along with the palmar plate  
        • origin
          • volar plate and intermetacarpal ligament at the metacarpal neck
        • insertion 
          • extensor mechanism (curving around radial and ulnar side of MCP joint)
      • retinacular ligaments
      • triangular ligament 
  • Sagital band
    • function 
      • the SB is the primary stabilizer of the extensor tendon at the MCP joint   
        • juncturae tendinum are the secondary stabilizers  
      • resists ulnar deviation of the tendon, especially during MCP flexion
      • prevents tendon bowstringing during MCP joing hyperextension
    • biomechanics
      • ulnar sagittal band
        • partial or complete sectioning does not lead to extensor tendon dislocation
      • radial sagittal band
        • distal sectioning does not produce extensor tendon instability
        • complete sectioning leads to extensor dislocation
        • sectioning of 50% of the proximal SB leads to extensor tendon subluxation
      • extensor tendon 
        • instability after sectioning is greater with wrist flexion  
        • instability after sectioning is greater in the central digits (than border digits)
          • the least stable tendon is the middle finger
          • the most stable tendon is the little finger
            • junctura tendinum stabilize the small finger 
Classification
 
Rayan and Murray Classification of Closed SB Injury
Type Description Image
Type I SB injury without extensor tendon instability
 
Type II SB injury with tendon subluxation

Type III SB injury with tendon dislocation
 
Presentation
  • Symptoms 
    • MCP soreness
  • Physical exam
    • tendon snapping
    • ulnar deviation of the digits at the MCP joint (rheumatoid arthritis)
    • inability to initiate extension
    • pseudo-triggering
    • extensor tendon dislocation into intermetacarpal gully
      • most unstable during MCP flexion with wrist flexed 
      • least unstable during MCP flexion with wrist extended
    • provocative test
      • pain when extending MCP joint against resistance (with both IP joints extended) 
Imaging
  • Radiographs
    • required views
      • hand PA, lateral, oblique
    • optional view
      • Brewerton view
        • AP with dorsal surface of fingers touching the cassette and MCP joints flexed 45deg
      • stress view
        • to rule out collateral ligament avulsion/injury
    • findings
      • exclude mechanical/bony pathology limiting extension, or predisposing to sagittal band rupture
      • may show dropped fingers and ulnar deviation in rheumatoid arthritis  
  • Ultrasound (dynamic)
    • indications
      • when swelling obscures the physical exam
    • findings
      • subluxation of EDC tendon relative to metacarpal head on MCP flexion  
  • MRI
    • indications
      • to establish diagnosis of SB disuption (radial or ulnar SB)
      • may show underlying etiology e.g. synovitis in rheumatoid arthritis
    • views
      • axial images at the level of the long MCP 
      • with MCP joint flexed for maximum EDC tendon displacement 
    • findings
      • poor definition, focal discontinuity and focal thickening in acute injury
      • subluxation of extensor tendon in radial direction due ulnar SB defec
      • dislocation of extensor tendon into ulnar intermetacarpal gully radial SB defect  
Differentials
  • MCP joint collateral ligament injury
  • EDC tendon rupture
  • Trigger finger
  • Junctura tendinum disruption
  • Congenital sagittal band deficiency
  • MCP joint arthritis
Treatment
  • Nonoperative
    • extension splint for 4-6 weeks  
      • indications
        • acute injuries (within one week)
  • Operative
    • direct repair (Kettlekamp)  
      • indications
        • chronic injuries (more than one week) where primary repair is possible
        • professional athlete 
    • extensor centralization procedure
      • indications
        • chronic injuries (more than one week) where primary repair is NOT possible
        • professional athlete
Techniques
  • Extensor Centralization Procedures
    • various techniques described including
      • trapdoor flap  
        • ulnar based partial thickness capsular flap created
        • tendon placed deep to flap
        • flap resutured to capsule
      • Kilgore tendon slip
        • distally based slip of EDC tendon on radial side
        • looped around radial collateral ligament
        • sutured to itself after tensioning to centralize tendon
      • Carroll tendon slip  
        • distally based slip of EDC tendon on ulnar side
        • routed deep to affected tendon and around radial collateral ligament
        • sutured to itself after tensioning to centralize tendon
      • McCoy tendon slip  
        • proximally based slip of EDC tendon
        • looped around lumbrical insertion
        • sutured to itself after tensioning to centralize tendon
      • Watson EDC tendon transfer post 
        • distally based slip of EDC tendon slip  
        • looped under deep transverse metacarpal ligament
        • weaved to remaining EDC tendon after tensioning to centralize tendon
      • Wheeldon junctural reinforcement  
        • for a middle finger radial SB rupture, the juncturae tendinum (JT) of the ring finger is is divided close to the ring finger, 
        • bring JT over the extensor tendon
        • attach JT to the torn SB  
      • fascial strips or free tendon graft

 

Please Rate Educational Value!
3.0
Average 3.0 of 16 Ratings

Qbank (2 Questions)

TAG
(OBQ12.262) A 28-year-old NFL running back complains of continued hand pain three days following an injury sustained while being tackled. He was splinted on the field. He has tenderness over the long finger metacarpal head, with subluxation of the extensor tendon into the intermetacarpal area during active metacarpophalangeal joint flexion. A representative MRI is shown in Figure A. What is the next best step in management of this patient? Topic Review Topic
FIGURES: A          

1. Observation alone
2. Continued splinting in flexion
3. Continued splinting in extension
4. Open repair of the disrupted junctura tendinae
5. Open repair of the disrupted sagittal band

PREFERRED RESPONSE ▶
TAG
(OBQ06.92) A 20-year-old man has pain, swelling, and popping over his index metacarpophalangeal joint after striking a wall a 3 days ago. Radiographs are normal, but physical exam reveals a palpable defect over the dorsum of the joint with clenching of the fist, and this defect is resolved with extension of the metacarpophalangeal joint. What is the next most appropriate step in treatment? Topic Review Topic

1. Trigger finger steroid injection
2. Extension splinting of the metacarpophalangeal joint
3. Metacarpophalangeal synovectomy
4. Extensor hood reconstruction
5. Metacarpophalangeal joint arthrodesis

PREFERRED RESPONSE ▶



Cases

Videos

video
Watson technique of sagittal band reconstruction. Distally based EDC tendon slip...
5/5/2013
468 views
4
video
Repair of the sagittal band centralizing the extensor tendon
1/23/2013
673 views
2
video
Physical exam findings of a patient with a sagittal band rupture
10/11/2012
1550 views
4
See More Videos

Posts

Groups


Evidence & References Show References




Topic Comments