AJR 2003; 180:655-658
© American Roentgen Ray Society
Posttraumatic Cystlike Defects of the Scaphoid: Late Sign of Occult Microfracture and Useful Indicator of Delayed Union
W. J. Rennie1 and
D. B. L. Finlay
1 Both authors: Department of Radiology, University Hospitals of Leicester,
Leicester Royal Infirmary, Hospital Close, Leicester LE1 5WW, United
Kingdom.
Received July 26, 2001;
accepted after revision August 22, 2002.
Address correspondence to W. J. Rennie.
Abstract
OBJECTIVE. To investigate the association between radiolucencies in
the scaphoid and trauma, we studied the unenhanced radiographs and CT images
of 1087 adult patients.
CONCLUSION. Three (0.3%) of the 1087 patients had scaphoid
radiolucencies that developed after trauma. We hypothesize that in these
patients a microfracture of the scaphoid or subtle fractures are the cause of
persisting clinical symptoms. Persistent loading of the scaphoid due to wrist
movement can lead to unrestricted compressive forces and ischemia and to the
development of a bone cyst-like pathologic change, apparent on the radiograph
as a radiolucency and often misreported as a cyst. An alternate term,
"cystlike defect" or "pseudocyst" of the scaphoid, is
suggested. Such radiolucencies are indicators of previous microfractures or an
untreated episode of trauma to the scaphoid.
Introduction
The incidence of fractures of the scaphoid is second only to fractures of
the distal radius in wrist injury
[1]. Diagnosis of a scaphoid
fracture is confirmed by an imaging study that reveals the fracture line, most
commonly a radiographic scaphoid series. However, immediately after injury, up
to 65% of scaphoid fractures remain radiographically occult
[2]. Patients who have no
apparent fracture on the follow-up radiograph but who have persistent symptoms
become a clinical conundrum, with limited treatment options. Some patients
develop focal radiolucencies in the scaphoid that are often reported as cysts.
These lesions in association with collapsing fractures may be difficult to
treat.
Materials and Methods
We retrospectively reviewed all radiographs and records of 1087 adult
patients who presented with a history of wrist trauma to the accident and
emergency department at the Leicester Royal Infirmary. The patients were
examined from April 2000 to April 2001 for evidence of scaphoid fractures and
radiolucencies. All suspected scaphoid fractures are treated on the basis of
clinical assessment in a below-elbow Colles' plaster cast, irrespective of the
radiologic findings; repeated radiography is performed within 10-14 days of
the casting. The patients and their radiographs are reviewed, and the decision
to continue treatment is made. The clinical criteria for scaphoid fracture
were pain, swelling, and tenderness in the anatomic snuffbox. Twenty-five
patients with symptoms of persistent pain underwent CT (Secura; Philips,
Eindhoven, The Netherlands) of the scaphoid with a 2-mm slice thickness per
2-mm collimation. The CT scans were obtained in the dorsovolar plane and were
reconstructed in the sagittal oblique plane. One patient who presented with
radiolucency of the scaphoid on the initial radiograph was excluded. CT was
used as the gold standard. The reviewers were unaware of the CT results.
In our study, three patients, all men from 18 to 39 years old (average, 25
years), developed focal radiolucencies in the scaphoid after trauma. On
reviewing their records, we found that they were all treated with a
below-elbow Colles' cast for 5-8 weeks (average, 6 weeks). Two patients
underwent surgical treatment, and one patient was lost to follow-up. Histology
was obtained for one patient with the specimen being reported as containing
areas of irregular fibrocartilagenous tissue merging with woven bone formation
and some cartilage with fibrin. The features were reported as in keeping with
a nonunited fracture.
Results
Both reviewers independently detected three cases of radiolucencies in the
scaphoid that developed after trauma to the wrist. The incidence of focal
radiolucencies after trauma to the scaphoid was low, involving three (0.3%) of
the 1087 patients (Figs. 1A,
1B,
1C,
1D,
2A,
2B,
2C,
3A,
3B). These focal radiolucencies
were confirmed on CT. CT showed fracture lines on the scaphoid of each
patient.
View larger version (141K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A. — 18-year-old man who is right-handed presented with history
of fall onto his right outstretched wrist while riding mountain bike. Initial
radiograph of scaphoid obtained 3 weeks after injury shows no obvious
fracture.
|
|
View larger version (98K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B. — 18-year-old man who is right-handed presented with history
of fall onto his right outstretched wrist while riding mountain bike.
Unenhanced radiograph obtained 6 weeks after plaster immobilization of wrist
was initially interpreted as showing no abnormality. On review, radiograph
shows subtle fracture line (arrowhead) along capitate surface of
scaphoid.
|
|
View larger version (100K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C. — 18-year-old man who is right-handed presented with history
of fall onto his right outstretched wrist while riding mountain bike.
Radiograph of scaphoid obtained 7 months after trauma shows radiolucency and
fracture running through it. Note increased sclerosis of proximal pole.
|
|
View larger version (131K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1D. — 18-year-old man who is right-handed presented with history
of fall onto his right outstretched wrist while riding mountain bike. CT scan
obtained 1 month after C shows focal radiolucency (-51 H) in scaphoid,
indicating fatty tissue in scaphoid complicated by fracture.
|
|
View larger version (114K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B. — 39-year-old man who is right-handed presented with history
of injury to his right wrist while fighting. Radiograph obtained 13 days after
A shows radiolucent area in waist of scaphoid with fracture.
|
|
View larger version (123K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2C. — 39-year-old man who is right-handed presented with history
of injury to his right wrist while fighting. CT scan obtained 1 week after
B shows focal radiolucent defect with oblique fracture through waist of
scaphoid.
|
|
View larger version (142K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B. — 20-year-old man with dorsiflexion injury to his wrist
incurred while playing soccer. Radiograph obtained 7 weeks after A
shows radiolucency in waist of scaphoid with marked osteopenia of carpus and
increased sclerosis of fracture lines.
|
|
Discussion
Fractures of the scaphoid have been explained as bone failure caused by
compressive or tension loads. Todd
[3] called these fractures
"snapped waist" fractures, similar to the response of a sugar lump
subjected to a tension load. Weber and Chao
[4] showed that for a fracture
of the scaphoid to be consistently reproduced under experimental conditions,
the load applied to the hand has to be concentrated on the radial half of the
palm with the wrist in 95-100° dorsiflexion.
In a scaphoid with a microfracture that is undetectable on radiography,
minor trauma resulting from wrist dorsiflexion and loading presumably serves
as the basis for an intraosseous lesion. This mechanism of continual minor
trauma is postulated in the evolution of ganglia because it initiates
intramedullary metaplasia and fibrous connective tissue proliferation, with or
without mucin secretion, which form a juxtaarticular bone cyst or bone
cyst-like pathologic change due to localized pressure atrophy
[5]. Schajowicz et al.
[6] and Eiken and Jonsson
[7] considered that mechanical
factors and repeated trauma in the superficial bone area are involved in the
development of intramedullary vascular disturbance. The resulting ischemia
with abnormal proliferation of fibrocartilage may be a contributory factor to
the radiolucent areas seen on radiography and are reported as the so-called
cystic change, although these lesions are histologically not cysts and should
therefore be reported as focal radiolucent areas.
Radiolucent focal lesions in the scaphoid or lunate, in association with a
collapsing fracture, are difficult to treat
[8]. Many modalities of
treatment exist, of which external fixation is one; external fixation is
useful in unloading the wrist joint after curettage and cancellous bone
grafting.
It has been our observation that in young patients with a history of a fall
onto the outstretched dorsiflexed wrist and persistent symptoms, a fracture
may be present that is not visible on radiography, even 14-21 days after the
injury. In these young active patients, constant micromovement and loading at
the fracture site can lead to ischemia and abnormal proliferation of
fibroblasts and cartilage, apparent on radiography as a radiolucency and often
reported as a cyst.
Only one case of a symptomatic focal radiolucency of the scaphoid that
developed after trauma in a 47-year-old woman has been reported in the
radiology literature. The researchers diagnosed it as a bone cyst-like
pathologic change related to the pathogenesis but atypical of a juxtaarticular
bone cyst [8].
Focal radiolucencies that develop after minor greenstick fractures in
children have been reported. These focal radiolucencies, unlike scaphoid focal
radiolucencies, are typically asymptomatic and occur just proximal to the
fracture line in the area of subperiosteal formation of new bone. Complete
resolution is the rule, with no adverse effect on fracture healing
[9].
Our observation stresses the importance of early diagnosis in patients with
persistent clinical symptoms related to the scaphoid. Persistent clinical
symptoms seem to be the only indication of an underlying problem. MR imaging,
with its greater sensitivity (95-100%) and specificity (100%), may be
appropriate at an earlier stage in these patients. Some researchers suggest
that the best diagnostic strategy in the treatment of clinically suspected
scaphoid fractures consists of initial radiography followed by MR imaging
rather than repeated radiography in patients with persistent symptoms and
negative findings on initial radiography
[10].
To our knowledge, these radiolucencies seem to occur only in the
microfracture group or in fractures that are subtle and can be missed on
radiography. These radiolucencies may indicate nonunion of the microfracture,
as the histology suggests. In all our patients, fracture lines were detected
on CT. The histology and CT value indicate these focal radiolucencies are not
true cysts containing fluid. "Cystlike defects" or
"pseudocysts" are suggested alternate terms that could be used in
reporting these lesions.
Although some patients in our study had wrist immobilization in plaster,
they went on to develop scaphoid nonunion. This condition may be caused by
either inadequate immobilization of these fractures or an inadequate period of
immobilization. Early detection of microfractures and wrist unloading with
longer periods of wrist immobilization may help to prevent subsequent cyst
formation. Because of the small numbers of scaphoid radioluciencies detected
in our study and the presumed low incidence of these cases, further imaging or
prospective animal model studies with sequential wrist-loading may be needed.
These studies may help to evaluate the time frame of evolution of these
radiolucencies and possibly improve the means of unloading the scaphoid to
improve the chance of healing.
References
- Taleisnik J. Fractures of the carpal bones. In: Green DP, ed.
Operative hand surgery, 3rd ed. New York: Churchill
Livingstone, 1993:745
-867
- Herneth AM, Seigmeth A, Bader TR, et al. Scaphoid fractures:
evaluation with high-spatial-resolution US initial results.
Radiology
2001;220:231
-235[Abstract/Free Full Text]
- Todd AH. Fractures of the carpal scaphoid. Br J
Surg 1921;9:7
-26
- Weber ER, Chao EY. An experimental approach to the mechanism of
scaphoid waist fractures. J Hand Surg Am
1978;3:142
-148[Medline]
- Feldman F, Johnston AD. Ganglia of bone: theories, manifestations,
and presentations. CRC Crit Rev Clin Radiol Nucl Med
1973;4:303
-332[Medline]
- Schajowicz F, Clavel Sainz M, Slullitel JA. Juxtaarticular bone
cysts (intra-osseous ganglia): a clinicopathological study of eighty-eight
cases. J Bone Joint Surg Br
1979;61:107
-116
- Eiken O, Jonsson K. Carpal bone cysts: a clinical and radiographic
study. Scand J Plast Reconstr Surg
1980;14:285
-290[Medline]
- Ikeda M, Oka Y. Cystic lesion in carpal bone. Hand
Surg 2000;5:25
-32[Medline]
- Ball CM, Dawe CJ. Transient postraumatic cystlike lesions of bone.
J Pediatr Orthop
2001;21:9
-13[Medline]
- Breitenseher MJ, Metz VM, Gilula LA, et al. Radiographically occult
scaphoid fractures: value of MR imaging in detection.
Radiology
1997;203:245
-250[Abstract/Free Full Text]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Top
Abstract
Introduction
