Sensitivity and Specificity of Radiographs in the Diagnosis of Little and/or Ring Carpometacarpal Joint Injuries

Abstract

Introduction Little and ring finger carpometacarpal joints (CMCJs) injuries are commonly missed due to misinterpretation of radiographs. We aimed to determine the sensitivity and specificity of four different radiographic views. Materials and Methods Radiographs (posteroanterior [PA], lateral [LAT], pronated oblique [POL], and supinated oblique [SOL] views) showing normal findings or little/ring finger CMCJ injuries were shown to two cohorts of orthopaedic trainees and a cohort of emergency nurse practitioners. Results The POL view performed best in all three testing scenarios. The SOL view performed least well. The combination of a PA, true LAT, and POL identified 78% of injuries correctly. In no cases did the SOL view correctly identify an injury when the other three views had been interpreted as normal. Conclusion We recommend a combination of the PA, POL, and LAT views in diagnosing these injuries. Where doubt remains, cross-sectional imaging is essential.

Keywords: carpometacarpal; dislocation; fracture; hamate; metacarpal.

Fig. 1

The four fracture–dislocation radiograph sets used throughout the study demonstrating the fracture–dislocation with a bony injury to the hamate.

Fig. 2

The metacarpal cascade lines.

Fig. 3

Multiple views in a patient with a punch injury. The tangential pronated oblique as evidenced by the lateral projection of the fourth and fifth metacarpals shows a small fragment corresponding with the dorsal lip of the hamate. At surgery, the fifth metacarpal was easily dislocatable, and transarticular wiring was performed. LAT, lateral; PA, posteroanterior.