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Age / Sex : 50 / M
Chief complaint: right wrist pain for 3-4 years 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: 김선정(Seon-Jeong Kim), 인제대해운대백병원(Inje University Haeundae Paik Hospital)
Diagnosis: SNAC (Scaphoid Nonunion Advanced Collapse)
Discussion
Findings:
Radiography and coronal CT of the right wrist
demonstrate a scaphoid nonunion and cyst in the scaphoid distal pole and radial
styloid.
Coronal T2
SPIR images of the right wrist show a fracture nonunion of scaphoid with high
signal between the fragments suggestive of pseudoarthrosis with a cyst in the
distal pole of scaphoid. Chondral loss at the radioscaphoid articulation is
also seen. Note tearing of scapholunate ligament and scapholunate dissociation.
Differential Diagnosis: Scapholunate Advanced collapse (SLAC)
Diagnosis:
Scaphoid Nonunion
Advanced Collapse (SNAC)
Discussion:
Long-standing scaphoid nonunion leads to
carpal collapse, known as scaphoid nonunion advanced collapse (SNAC) wrist. Scaphoid
nonunion is most commonly seen in males in second or third decade with
proximal-thrid fractures or vertical oblique fractures of the middle third. It
is characterized by sclerosis, cyst formation, flexion (humpback) deformity and
dorsal intercalated segment instability deformity. Scaphoid nonunion will progress
to wrist instability and subsequent arthritis, if inadequately treated. The
abnormal loading and progression of degenerative changes are similar to those
in SLAC.
Radiographic
features of SNAC wrist
l Non-united scaphoid fracture
l Marked osteoarthritis of the
radioscaphoid joint
l Radiolunate joint is usually spared
from degenerative involvement
l Most patients with SNAC wrist with
nonunion of the middle or distal third of the scaphoid also have dorsal
intercalated segment instability (DISI)
Stage
l Stage 1 : osteoarthritis between the
distal scaphoid fragment and the radial styloid process
l Stage 2 : stage 1 with the addition
of osteoarthritis between the scaphoid and the capitate
l Stage 3 : osteoarthritis affecting
the radial styloid, distal scaphoid, and scaphocapitate with progression to the
lunocapitate
References:
1. Goldfarb CA, Yin Y, Gilula LA et
al. Wrist fractures: what the clinician wants to know. Radiology.
2001;219:11-28.
2. Mack MG, Keim S, Balzer JO.
Clinical impact of MRI in acute wrist fractures. Eur Radiol. 2003;13: 612-617.
3. Oneson SR, Scales LM, Erickson
SJ. MR imaging of the painful wrist. Radiographics. 1996;16:997-1008.
4. Crema MD, Zentner J, Guermazi A et
al. Scapholunate advanced collapse and scaphoid nonunion advanced collapse: MDCT
arthrography features. AJR Am J Roentgenol. 2012 ;199:W202-207.
5. Resnick D. Diagnosis of
Bone and Joint Disorders. 4th ed. WB Saunders. 2002;2:1310-1311,
1611.
6. Stoller DW. Magnetic Resonance
Imaging in Orthopaedics and Sports Medicine. 3rd ed. Lippincott Williams &
Wilkins. 2007;1774-1779.
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