Comparisons of Three Radiographic Views in Assessing for Scapholunate Instability

Abstract

Background Multiple wrist x-ray images have been described to assess for scapholunate (SL) instability. Some views may be redundant. The purpose of this study was to compare three plain x-ray views in identifying a traumatic diastasis of the SL interval. Methods Nineteen patients (19 wrists) with a positive scaphoid shift test and surgically confirmed SL ligament damage were identified. There were 15 males and 4 females with a mean age of 39 years. Pre-operative x-rays were reviewed, including posteroanterior (PA) neutral and PA ulnar deviation views of the injured wrist, and PA clenched fist views of the injured and uninjured wrists. Dynamic SL instability was defined by an SL mid-interval gap of <3 mm and static SL instability by a gap of ≥3 mm in the PA neutral views. The mid-interval measurements were compared between x-ray images. Results There were 10 dynamic and 9 static SL instability cases. The PA ulnar deviation and the PA clenched fist views showed significantly greater SL gaps in comparison to the PA neutral views in dynamic but not static SL instability cases. In both categories of instability, there was no significant difference in the SL gaps between the two stress images. The PA clenched fist view of the uninjured wrist revealed SL gapping of >3 mm in 50% of patients but with generally greater gapping in the clenched fist view of the injured wrist. Conclusions The PA ulnar deviation and clenched fist stress views were equally effective in showing a dynamic SL diastasis following wrist injury. Neither view was more effective than a neutral PA view in diagnosing static SL instability.

Dynamic CT Scan of the Normal Scapholunate Joint in a Clenched Fist and Radial and Ulnar Deviation

“…Widening of the scapholunate >3 mm on the clenched fist view has been recognized as an indication of possible disruption of the scapholunate ligament. 14,18 In our sample of normal wrists, the clenching of the fist and radial and ulnar deviation show minimal change in the scaphoid and lunate position relative to one another (<2 mm). The normal scapholunate ligament maintains the position of the 2 bones throughout a full range in the coronal plane, as well as with clenching the fist.…”

“…2 The clenched fist view has previously been studied in scapholunate dissociation, and our goal was to assess the normal joint behavior in this position using dynamic CT imaging. 14,17,18 The advancements in CT scanning and software to utilize dynamic CT (4D CT) analysis have created a unique modality to examine the wrist. 4 Our goal was to establish a protocol for measurements of the normal joint, on a novel dynamic CT wrist scan.…”

The Twist X-Ray: A Novel Test for Dynamic Scapholunate Instability

“…4 In a further study by Patel et al, they compared multiple views including PA neutral, PA ulnar deviation, and PA clenched fist and showed that PA ulnar deviation and clenched fist were equal in detecting dynamic SLI. 7 Unfortunately, in that study, the method to perform the clenched fist view was not described.…”

“…Various dynamic tests have been described to improve the detection of scapholunate ligament injuries. 4,7,8 The clenched fist view has been an important addition to the armamentarium of X-ray views used to diagnose dynamic SLI. 8 The view accentuates the scapholunate gap secondary to the scapholunate ligament incompetence by driving the capitate proximally into the disrupted interval.…”

Radiographs Detect Dorsal Scaphoid Translation in Scapholunate Dissociation

“…SL gap was measured on PA wrist radiographs in the midportion of the scaphoid and lunate. [11][12][13] All other angles were measured on true lateral wrist radiographs in 0 degrees of wrist extension by tracing the longitudinal axes of the appropriate carpal bones. 14,15 The scaphoid axis was represented by a tangential line connecting the palmar convexities of the proximal and distal poles.…”