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Age / Sex : 59 / F
Chief complaint: 1) Finger deformity of left 3rd finger, no pain, not easy to flex
the affected PIP joint
2) Trauma Hx (+), 1YA
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: Ja-Young, Choi, Seoul National
University Hospital
Diagnosis: Volar plate injury
Discussion
Findings:
1)
X-ray: Swan
neck deformity of left long finger (hyperextension of PIP joint and flexion of
DIP joint) is noted.
2)
MRI: Sagittal
FS T2WI shows a complete detachment of the volar plate (VP) from the middle
phalangeal base with marked retraction of the torn VP fragment at the proximal
phalangeal neck level.
Differential Diagnosis:
** Swan neck
deformity
1)
Post-traumatic:
mallet finger injury, volar plate injury
2)
Rheumatoid
arthritis, scleroderma, psoriatic arthritis, SLE arthropathy, etc
Diagnosis:
Volar plate injury of the PIP joint
Discussion:
The volar plate is a thick fibrocartilaginous
structure that contributes the palmar aspect of the PIP joint capsule, and is
distally attached to the middle phalangeal base, and proximally to the proximal
phalangeal shaft. The volar plate prevents hyperextension of the PIP joint.
The common causes of volar plate
injuries are sports or fall where the finger is bent backward (i.e. hyperextension),
or force is applied to the fingertip (ex. ball hitting fingertip). Such a
hyperextension results in avulsion of the VP from the base of the middle
phalanx or less frequently from the proximal insertion point of the VP. The
volar plate can be partially or completely torn, with or without an avulsion
fracture. Without adequate treatment, natural evolution of distal disruption of
the VP from the middle phalanx is hyperextension of the affected PIP joint,
resulting in swan neck deformity. In contrast, proximal disruption of the VP
from the proximal phalanx can lead to pseudoboutonniere deformity. Radiographs
show an avulsion fragment at the base of the affected phalanx. MRI can more
definitively depict the volar plate abnormalities as well as bone and soft
tissue edema and adjacent fluid collection. Treatment options are conservative
and range from early active motion with or without buddy strapping to
immobilization at various degrees of flexion/extension. However, referral
criteria include an unstable joint or a large avulsion fragment.
References:
1.
Chung CB, Aguiar
R. MRI of finger ligaments. In: CB Chung, Steinbach LS, ed. MRI of the upper
extremity: shoulder, elbow, wrist and hand. Philadelpia, Pa: JB Lippincott;
2010: 611-624.
2.
Kang R,
Stern PJ. Fracture dislocations of the proximal interphalangeal joint. J Am Soc
Surg Hand 2002;2(2):47-59.
3.
Leggit JC1,
Meko CJ. Acute finger injuries: part I. Tendons and ligaments. Am Fam
Physician. 2006 Mar 1;73(5):810-6.
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