Age / Sex : 34 / M

Chief complaint: right 2nd finger pain and swelling

1) What is your impression?

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

(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)

Courtesy: 이승훈(Lee Seunghun), 한양대병원(Hanyang University Hospital)

Tearing of sagittal bands of extensor hood, 2nd finger

Discussion

Findings

•      
Axial MRI> On T1WI and T2WI, complete
rupture of radial side sagittal band with ulnar subluxation of extensor
digitorum tendon at the MCP joint.

Discussion:

•       Subluxation and dislocation of the
extensor digitorum communis tendon at MCP joint

•       Mechamism

-      
Direct blow
forcing the finger into flexion

-      
Forced
flexion and ulnar deviation of the finger (Boxer’s knuckle)

•       Ulnar subluxation : more common

-      
Forced
valgus injury : radial subluxation

•       Usually the middle finger

•       Clinical examination,

-      
pain and
swelling over the MCP joint

-   inability to
completely extend the MCP joint

-  
chronic untreated cases : multiple episodes of pain and swelling over
the MPC joint with a snapping sensation in the finger

•      
Treatment

-  Acute; conservative
treatment with splinting of the MCP joint in extension

- 
chronic symptomatic - surgical correction

References:

1. Lopez-Ben R, et al. Boxer Knuckle (Injury of the
   Extensor Hood with Extensor Tendon Subluxation): Diagnosis with Dynamic
   US-Report of Three Cases. Radiology 2003;
   228:642–646


2. Clavero JA, et al. Extensor
   Mechanism of the Fingers: MR Imaging–Anatomic Correlation. Radiographics 2003; 23:593–611


3. Clavero JA, et al. MR Imaging
   of Ligament and Tendon Injuries of the Fingers. Radiographics 2002; 22:237–256


4. Magnetic resonance imaging in
   orthopaedics and sports medicine, 3^rd edition, 1859-1868