Weekly Case

Title : case 411

Age / Sex : 21 / M



Chief complaint: finger pain after trauma

What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Please submit only one answer)


 


 


 


Courtesy: Hye Jin Ryu, Seoul national university hospital


 


Diagnosis:

Sagittal band tear



Discussion


Findings:


Absence of radial sagittal band at MCP joint level.


Fluid-equivalent signal intensity at the radial sagittal band tear site.


- with mild ulnar subluxation of 3rd extensor tendon


- with surrounding soft tissue edema


 


Differential Diagnosis:


MCP joint collateral ligament injury


EDC tendon rupture


Trigger finger


Junctura tendinum disruption


Congenital sagittal band deficiency


MCP joint arthritis


Diagnosis:  


Sagittal band tear


 


Discussion:


      Sagittal band (SB) rupture leads to dislocation of the extensor tendon  


      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


MRI


      indications


      to establish diagnosis of SB disruption (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 ulnar direction due radial SB defect  


      dislocation of extensor tendon into ulnar intermetacarpal gully radial SB defect 


 


References:


 Functional anatomy of the thumb sagittal band J Hand Surg Am. 2008 Jul-Aug;33(6):879-84. 


The sagittal band: anatomic and biomechanical study J Hand Surg Am. 2000 Nov;25(6):1107-13.



Correct Answer
Name Institution
이름:소속병원
Total Applicants: 24
Correct answers:24
전성희:중앙보훈병원
이은주:리더스병원
이혜란:석병원
박지원:대구 참튼튼병원
최마리아:예병원
김지현:하이병원
최현진:인하대병원
LE TRONG BINH:인하대병원
신윤상:인하대병원
이택기:인하대병원
김유진:인하대병원
우아름:인하대병원
신재환:서울 백병원
윤민아:고대 구로병원
이선영:대림 성모병원
김현수:병무청
윤유성:삼기보건지소
이지현:병무청
손상욱:단국대병원
이수현:충북대병원
김하연:인하대병원
김지민:순천향대 천안병원
김정례:단국대병원
조신영:웰튼 병원

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