Published online Sep 28, 2017. doi: 10.4329/wjr.v9.i9.359
Peer-review started: January 20, 2017
First decision: May 22, 2017
Revised: June 26, 2017
Accepted: July 14, 2017
Article in press: July 17, 2017
Published online: September 28, 2017
To evaluate the reliability of pronator quadratus fat pad sign to detect distal radius fracture and to predict its severity.
Retrospectively we identified 89 consecutive patients (41 female, mean age 49 ± 18 years) who had X-ray (CR) and computed tomography (CT) within 24 h following distal forearm trauma. Thickness of pronator quadratus fat pad complex (PQC) was measured using lateral views (CR) and sagittal reconstructions (CT). Pearson’s test was used to determine the correlation of the PQC thickness in CR and CT. A positive pronator quadratus sign (PQS) was defined as a PQC > 8.0 mm (female) or > 9.0 mm (male). Frykman classification was utilized to assess the severity of fractures.
Forty-four/89 patients (49%) had a distal radius fracture (Frykman I n = 3, II n = 0, III n = 10, IV n = 5, V n = 2, VI n = 2, VII n = 9, VIII n = 13). Mean thickness of the PQC thickness can reliably be measured on X-ray views and was 7.5 ± 2.8 mm in lateral views (CR), respectively 9.4 ± 3.0 mm in sagittal reconstructions (CT), resulting in a significant correlation coefficient of 0.795. A positive PQS at CR was present in 21/44 patients (48%) with distal radius fracture and in 2/45 patients (4%) without distal radius fracture, resulting in a specificity of 96% and a sensitivity of 48% for the detection of distal radius fractures. There was no correlation between thickness of the PQC and severity of distal radius fractures.
A positive PQS shows high specificity but low sensitivity for detection of distal radius fractures. The PQC thickness cannot predict the severity of distal radius fractures.
Core tip: This study evaluated reliability of pronator quadratus fat pad sign (PQS) to detect distal radius fracture and to predict its severity. Therefore correlation of measurements of pronator quadratus complex (PQC) on conventional lateral radiographs (CR) and sagittal reconstructions of computed tomographies (CT), also regarding the severity of fractures were analyzed. In conclusion PQC thickness can reliably be measured on lateral CR and correlates with CT. Sensitivity of PQS for detecting fractures is low, but specificity is high. Therefore a positive PQS in putative negative radiograph should trigger further investigations, e.g., CT scan. PQC thickness cannot predict severity of wrist fractures.