Pronator quadratus sign
Updates to Article Attributes
The pronator quadratus sign can be an indirect sign of distal forearm trauma. It relies on displacement of the fat pad that lies superficial to the pronator quadratus muscle.
Pathology
Displacement, anterior bowing, or obliteration of the fat plane in the setting of trauma may indicate a distal radius or ulna fracture. Various studies have described a high specificity but wide-ranging sensitivity for fracture ranging from 26 to 98%; thus a negative pronator quadratus sign does not exclude fracture 1,2,4.
In the absence of trauma, there are other causes for a positive pronator quadratus sign:
- muscle strain or haematoma
- inflammatory conditions
- infectious conditions, e.g. osteomyelitis, cellulitis
- septic arthritis of the wrist
Radiographic features
Plain radiograph
On lateral wrist radiographs, the pronator fat pad normally appears as a thin radiolucent triangle, with its base attached to the palmar surface of the distal radius 1,2. It is observed ~90% of the time 1.
Pathology
Displacement One study 4, anterior bowing, or obliterationhas suggested a cut-off of the fat plane in the setting of trauma may indicate<8 mm (female) and 9 mm (male) on lateral x-rays as a distal radius or ulna fracture. Various studies have described a wide ranging sensitivitycut-off for fracture ranging from 26 to 98%; thus a negative pronator quadratus sign does not exclude fracture 1-2
In the absence of trauma, there are other causes for a positive pronator quadratus sign:
muscle strain or haematomainflammatory conditionsinfectious conditions, e.g. osteomyelitis or cellulitisseptic arthritis of the wrist
History and etymology
It was first described by MacEwan in 1964 3.
-<p>The <strong>pronator quadratus sign</strong> can be an indirect sign of distal forearm trauma. It relies on displacement of the fat pad that lies superficial to the <a href="/articles/pronator-quadratus">pronator quadratus muscle</a>.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>On lateral wrist radiographs, the pronator fat pad normally appears as a thin radiolucent triangle, with its base attached to the palmar surface of the distal radius <sup>1,2</sup>. It is observed ~90% of the time <sup>1</sup>.</p><h4>Pathology</h4><p>Displacement, anterior bowing, or obliteration of the fat plane in the setting of trauma may indicate a distal radius or ulna fracture. Various studies have described a wide ranging sensitivity for fracture ranging from 26 to 98%; thus a negative pronator quadratus sign does not exclude fracture <sup>1-2</sup>.</p><p>In the absence of trauma, there are other causes for a positive pronator quadratus sign:</p><ul>- +<p>The <strong>pronator quadratus sign</strong> can be an indirect sign of distal forearm trauma. It relies on displacement of the fat pad that lies superficial to the <a href="/articles/pronator-quadratus">pronator quadratus muscle</a>.</p><h4>Pathology</h4><p>Displacement, anterior bowing, or obliteration of the fat plane in the setting of trauma may indicate a distal radius or ulna fracture. Various studies have described a high specificity but wide-ranging sensitivity for fracture ranging from 26 to 98%; thus a negative pronator quadratus sign does not exclude fracture <sup>1,2,4</sup>.</p><p>In the absence of trauma, there are other causes for a positive pronator quadratus sign:</p><ul>
-<li>infectious conditions, e.g. osteomyelitis or cellulitis</li>-<li>septic arthritis of the wrist</li>-</ul><h4>History and etymology</h4><p>It was first described by <strong>MacEwan</strong> in 1964 <sup>3</sup>.</p>- +<li>infectious conditions, e.g. <a title="Osteomyelitis" href="/articles/osteomyelitis">osteomyelitis</a>, cellulitis</li>
- +<li>
- +<a title="Septic arthritis" href="/articles/septic-arthritis">septic arthritis</a> of the wrist</li>
- +</ul><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>On lateral wrist radiographs, the pronator fat pad normally appears as a thin radiolucent triangle, with its base attached to the palmar surface of the distal radius <sup>1,2</sup>. It is observed ~90% of the time <sup>1</sup>. One study <sup>4</sup>, has suggested a cut-off of <8 mm (female) and 9 mm (male) on lateral x-rays as a cut-off for normal.</p><h4>History and etymology</h4><p>It was first described by <strong>MacEwan</strong> in 1964 <sup>3</sup>.</p>
References changed:
- 4. Loesaus J, Wobbe I, Stahlberg E, Barkhausen J, Goltz J. Reliability of the Pronator Quadratus Fat Pad Sign to Predict the Severity of Distal Radius Fractures. World J Radiol. 2017;9(9):359-64. <a href="https://doi.org/10.4329/wjr.v9.i9.359">doi:10.4329/wjr.v9.i9.359</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/29098069">Pubmed</a>
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